v2.3.0: save and restore messages when the server is restarted (#395)

* save and restore messages when server is restarted

* read file line by line

* add import

* optmize restoring messages by reading the whole file

* update version to 2.3.0

* update scripts

* add script

* update readme

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @epoberezkin @efim-poberezkin

.github/FUNDING.yml

@@ -0,0 +1,2 @@
+github: simplex-chat
+open_collective: simplex-chat

.github/changelog_conf.json

@@ -0,0 +1,4 @@
+{
+  "template": "${{UNCATEGORIZED}}",
+  "pr_template": "- ${{TITLE}}"
+}

.github/workflows/build.yml

@@ -0,0 +1,80 @@
+name: build
+
+on:
+  push:
+    branches:
+      - master
+      - stable
+    tags:
+      - "v*"
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Clone project
+        uses: actions/checkout@v2
+
+      - name: Setup Stack
+        uses: haskell/actions/setup@v1
+        with:
+          ghc-version: "8.10.7"
+          enable-stack: true
+          stack-version: "latest"
+
+      - name: Cache dependencies
+        uses: actions/cache@v2
+        with:
+          path: ~/.stack
+          key: ${{ hashFiles('stack.yaml') }}
+
+      - name: Build & test
+        id: build_test
+        shell: bash
+        run: |
+          stack build --test --force-dirty
+          install_root=$(stack path --local-install-root)
+          mv ${install_root}/bin/smp-server smp-server-ubuntu-20_04-x86-64
+          mv ${install_root}/bin/ntf-server ntf-server-ubuntu-20_04-x86-64
+
+      - name: Build changelog
+        if: startsWith(github.ref, 'refs/tags/v')
+        id: build_changelog
+        uses: mikepenz/release-changelog-builder-action@v1
+        with:
+          configuration: .github/changelog_conf.json
+          failOnError: true
+          ignorePreReleases: true
+          commitMode: true
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract release candidate
+        if: startsWith(github.ref, 'refs/tags/v')
+        id: extract_release_candidate
+        shell: bash
+        run: |
+          if [[ ${GITHUB_REF} == *rc* ]]; then
+            echo "::set-output name=release_candidate::true"
+          else
+            echo "::set-output name=release_candidate::false"
+          fi
+
+      - name: Create release
+        if: startsWith(github.ref, 'refs/tags/v')
+        uses: softprops/action-gh-release@v1
+        with:
+          body: |
+            See full changelog [here](https://github.com/simplex-chat/simplexmq/blob/master/CHANGELOG.md).
+
+            Commits:
+            ${{ steps.build_changelog.outputs.changelog }}
+          prerelease: ${{ steps.extract_release_candidate.outputs.release_candidate }}
+          files: |
+            LICENSE
+            smp-server-ubuntu-20_04-x86-64
+            ntf-server-ubuntu-20_04-x86-64
+          fail_on_unmatched_files: true
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -1,2 +1,6 @@
 *.lock
-*.cabal
+*.db
+*.db.bak
+*.session.sql
+tests/tmp
+dist-newstyle/

CHANGELOG.md

@@ -0,0 +1,205 @@
+# 2.3.0
+
+SMP server:
+
+- Save and restore undelivered messages, to avoid losing them. To save messages the server has to be stopped with SIGINT signal, if it is stopped with SIGTERM undelivered messages would not be saved.
+
+# 2.2.0
+
+SMP server:
+
+- Fix sockets/threads/memory leak
+
+SMP agent:
+
+- Support stopping and resuming agent with `disconnectAgentClient` / `resumeAgentClient`
+
+# 2.1.1
+
+SMP server:
+
+- gracefully close sockets on client disconnection
+- CLI warning when deleting server configuration
+
+# 2.1.0
+
+SMP server:
+
+- configuration to expire inactive clients in ini file, increased TTL and check interval for client expiration
+
+# 2.0.0
+
+Push notifications server (beta):
+
+- supports APNS
+- manage device tokens verification via notification delivery
+- sending periodic background notification to check messages (not more frequent than every 20 min)
+
+SMP server:
+
+- disconnect inactive clients after some period
+- remove undelivered messages after 30 days
+- log aggregate usage daily stats: only the number of queues created/secured/deleted/used and messages sent/delivered is logged, as one line per day, so we can plan server capacity and diagnose any problems.
+
+SMP agent:
+
+- manage device tokens and notification server connection
+- DOWN/UP events to the agent user about server disconnections/reconnections are now sent once per server
+
+# 1.1.0
+
+SMP server:
+
+- message TTL and periodic deletion of old messages
+- configuration to prevent creation of the new queues
+
+SMP agent:
+
+- asynchronous connection handshake
+- configurable SMP servers at run-time
+- use TCP keep-alive for connection stability
+- improve stability of connection subscriptions
+- auto-vacuum DB to remove deleted records
+
+# 1.0.3
+
+SMP server:
+
+- Reduce server message queue quota to 128 messages.
+
+SMP agent:
+
+- Add "yes to migrations" option.
+- Make new SMP client attempt to reconnect on network error.
+- Reduce connection handshake expiration to 2 days.
+
+JSON encoding of types used in simplex-chat, some other minor adjustments.
+
+# 1.0.2
+
+General:
+
+- Enable TLS 1.3 parameters for TLS handshake (server and client).
+- Switch from hs-tls fork to original repo now that it supports getFinished and getPeerFinished APIs for both TLS 1.2 and TLS 1.3.
+
+SMP server:
+
+- Perform TLS handshake in a separate thread per-connection.
+
+SMP agent:
+
+- Cease attempts to send HELLO after one week timeout.
+- Coalesce requests to connect to SMP servers, to have 1 connection per server.
+
+# 1.0.1
+
+SMP server:
+
+- Explicitly set line buffering in stdout/stderr to log each line when output is redirected to files.
+
+# 1.0.0
+
+Security and privacy improvements:
+
+- Faster and more secure 2-layer E2E encryption with additional encryption layer between servers and recipients:
+  - application messages in each duplex connection (managed by SMP agents - see [overview](https://github.com/simplex-chat/simplexmq/blob/master/protocol/overview-tjr.md)) are encrypted using [double-ratchet algorithm](https://www.signal.org/docs/specifications/doubleratchet/), providing forward secrecy and break-in recovery. This layer uses two Curve448 keys per client for [X3DH key agreement](https://www.signal.org/docs/specifications/x3dh/), SHA512 based HKDFs and AES-GCM AEAD encryption.
+  - SMP client messages are additionally E2E encrypted in each SMP queue to avoid cipher-text correlation of messages sent via multiple redundant queues (that will be supported soon). This and the next layer use [NaCl crypto_box algorithm](https://nacl.cr.yp.to/index.html) with XSalsa20Poly1305 cipher and Curve25519 keys for DH key agreement.
+  - Messages delivered from the servers to the recipients are additionally encrypted to avoid cipher-text correlation between sent and received messages.
+- To prevent any traffic correlation by content size, SimpleX uses fixed transport block size of 16kb (16384 bytes) with padding on all encryption layers:
+  - application messages are padded to 15788 bytes before E2E double-ratchet encryption.
+  - messages between SMP clients are padded to 16032 bytes before E2E encryption in each SMP queue.
+  - messages from the server to the recipient are padded to padded to 16088 bytes before the additional encryption layer (see above).
+- TLS 1.2+ with tls-unique channel binding in each command to prevent replay attacks.
+- Server identity verification via server offline certificate fingerprints included in SMP server addresses.
+
+New functionality:
+
+- Support for notification servers with new SMP commands: `NKEY`/`NID`, `NSUB`/`NMSG`.
+
+Efficiency improvements:
+
+- Binary protocol encodings to reduce overhead from circa 15% to approximately 3.7% of transmitted application message size, with only 2.2% overhead for SMP protocol messages.
+- More performant cryptographic algorithms.
+
+For more information about SimpleX:
+
+- [SimpleX overview](https://github.com/simplex-chat/simplexmq/blob/master/protocol/overview-tjr.md).
+- [SimpleX chat v1 announcement](https://github.com/simplex-chat/simplex-chat/blob/master/blog/20220112-simplex-chat-v1-released.md).
+
+# 0.5.2
+
+- Fix message delivery logic that blocked delivery of all server messages when server per-queue quota exceeded, making it concurrent per SMP queue, not per server.
+
+# 0.5.1
+
+- Fix server subscription logic bug that was leading to memory leak / resource exhaustion in some edge cases.
+
+# 0.5.0
+
+- No changes in SMP server implementation - it is backwards compatible with v0.4.1
+- SMP agent changes:
+  - URI syntax for SMP queues and connection requests.
+  - long-term connections links ("contacts") in SMP agent protocol.
+  - agent command changes:
+    - `REQ` notification and `ACPT` command are used only with long-term connection links.
+    - `CONF` notification and `LET` commands are used for normal duplex connections.
+
+# 0.4.1
+
+- Include migrations in the package
+
+# 0.4.0
+
+- SMP server implementation and [SMP protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md) changes:
+  - support 3072 bit RSA key size
+  - add SMP queue quotas
+  - set default transport block size to 4096 bits
+  - allow SMP client to change transport block size during transport connection handshake
+- SMP agent implementation and protocol changes:
+  - additional connection confirmation step for initiating party
+  - automatically resume subscribed duplex connections once transport connection is resumed
+  - passing an arbitrary binary information between parties during the duplex connection handshake - can be used to identify parties
+  - asynchronous duplex connection handshake - the parties do not have to be online at the same time
+  - asynchronous message delivery - the agent does not need transport connection to accept client messages for delivery
+  - additional confirmation of message reception from the client to prevent message loss in case of process termination
+  - set transport block size to 8192 bits (in the future the agent protocol can allow to have different block sizes for different duplex connections)
+  - added client commands and notifications (see [agent protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md)):
+    - `REQ` - the notification about joining party establishing connection
+    - `ACPT` - the command to accept connection with the joining party
+    - `INFO` - the notification with the information from the initiating party
+    - `DOWN`/`UP` - the notifications about losing/resuming the connection
+    - `ACK` - the command to confirm that the message reception/processing is complete
+    - `MID` - the response to `SEND` confirming that the message is accepted by the agent
+    - `MERR` - the notification about permanent message delivery error (e.g., `ERR AUTH` indicating that the queue was removed)
+
+# 0.3.2
+
+- Support websockets
+- SMP server CLI commands
+
+# 0.3.1
+
+- Released to hackage.org
+- SMP agent protocol changes:
+  - move SMP server from agent commands NEW/JOIN to agent config
+  - send CON to user only when the 1st party responds HELLO
+- Fix REPLY vulnerability
+- Fix transaction busy error
+
+# 0.3.0
+
+- SMP encrypted transport over TCP
+- Standard X509/PKCS8 encoding for RSA keys
+- Sign and verify agent messages
+- Verify message integrity based on previous message hash and ID
+- Prevent timing attack allowing to determine if queue exists
+- Only allow correct RSA keys and signature sizes
+
+# 0.2.0
+
+- SMP client library
+- SMP agent with E2E encryption
+
+# 0.1.0
+
+- SMP protocol server implementation without encryption

README.md

@@ -1,93 +1,173 @@
-# simplex-messaging
+# SimpleXMQ
 
-## SMP server demo
+[![GitHub build](https://github.com/simplex-chat/simplexmq/workflows/build/badge.svg)](https://github.com/simplex-chat/simplexmq/actions?query=workflow%3Abuild)
+[![GitHub release](https://img.shields.io/github/v/release/simplex-chat/simplexmq)](https://github.com/simplex-chat/simplexmq/releases)
 
-This is a demo implementation of SMP ([simplex messaging protocol](https://github.com/simplex-chat/protocol/blob/master/simplex-messaging.md)) server.
+📢 SimpleXMQ v1 is released - with many security, privacy and efficiency improvements, new functionality - see [release notes](https://github.com/simplex-chat/simplexmq/releases/tag/v1.0.0).
 
-It has a very limited utility (if any) for real applications, as it lacks the following protocol features:
+**Please note**: v1 is not backwards compatible, but it has the version negotiation built into all protocol layers for forwards compatibility of this version and backwards compatibility of the future versions, that will be backwards compatible for at least two versions back.
 
-- cryptographic signature verification, instead it simply compares provided "signature" with stored "public key", effectively treating them as plain text passwords.
-- there is no transport encryption
+If you have a server deployed please deploy a new server to a new host and retire the previous version once it is no longer used.
 
-Because of these limitations, it is easy to experiment with the protocol logic via telnet.
+## Message broker for unidirectional (simplex) queues
 
-You can either run it locally or try with the deployed demo server:
+SimpleXMQ is a message broker for managing message queues and sending messages over public network. It consists of SMP server, SMP client library and SMP agent that implement [SMP protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md) for client-server communication and [SMP agent protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md) to manage duplex connections via simplex queues on multiple SMP servers.
 
-```bash
-telnet smp.simplex.im 5223
+SMP protocol is inspired by [Redis serialization protocol](https://redis.io/topics/protocol), but it is much simpler - it currently has only 10 client commands and 8 server responses.
+
+SimpleXMQ is implemented in Haskell - it benefits from robust software transactional memory (STM) and concurrency primitives that Haskell provides.
+
+## SimpleXMQ roadmap
+
+- SimpleX service protocol and application template - to enable users building services and chat bots that work over SimpleX protocol stack. The first such service will be a notification service for a mobile app.
+- SMP queue redundancy and rotation in SMP agent connections.
+- SMP agents synchronization to share connections and messages between multiple agents (it would allow using multiple devices for [simplex-chat](https://github.com/simplex-chat/simplex-chat)).
+
+## Components
+
+### SMP server
+
+[SMP server](https://github.com/simplex-chat/simplexmq/blob/master/apps/smp-server/Main.hs) can be run on any Linux distribution, including low power/low memory devices. OpenSSL library is required for initialization.
+
+To initialize the server use `smp-server init -n <fqdn>` (or `smp-server init --ip <ip>` for IP based address) command - it will generate keys and certificates for TLS transport. The fingerprint of offline certificate is used as part of the server address to protect client/server connection against man-in-the-middle attacks: `smp://<fingerprint>@<hostname>[:5223]`.
+
+SMP server uses in-memory persistence with an optional append-only log of created queues that allows to re-start the server without losing the connections. This log is compacted on every server restart, permanently removing suspended and removed queues.
+
+To enable store log, initialize server using `smp-server -l` command, or modify `smp-server.ini` created during initialization (uncomment `enable: on` option in the store log section). Use `smp-server --help` for other usage tips.
+
+Starting from version 2.3.0, when store log is enabled, the server would also enable saving undelivered messages on exit and restoring them on start. This can be disabled via a separate setting `restore_messages` in `smp-server.ini` file. Saving messages would only work if the server is stopped with SIGINT signal (keyboard interrupt), if it is stopped with SIGTERM signal the messages would not be saved.
+
+> **Please note:** On initialization SMP server creates a chain of two certificates: a self-signed CA certificate ("offline") and a server certificate used for TLS handshake ("online"). **You should store CA certificate private key securely and delete it from the server. If server TLS credential is compromised this key can be used to sign a new one, keeping the same server identity and established connections.** CA private key location by default is `/etc/opt/simplex/ca.key`.
+
+SMP server implements [SMP protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md).
+
+#### Running SMP server on MacOS
+
+SMP server requires OpenSSL library for initialization. On MacOS OpenSSL library may be replaced with LibreSSL, which doesn't support required algorithms. Before initializing SMP server verify you have OpenSSL installed:
+
+```sh
+openssl version
 ```
 
-## Run locally
+If it says "LibreSSL", please install original OpenSSL:
 
-[Install stack](https://docs.haskellstack.org/en/stable/install_and_upgrade/) and `stack run`.
-
-## Usage example
-
-Lines you should send are prefixed with `>` character, you should not type them.
-
-Comments are prefixed with `--`, they are not part of transmissions.
-
-`>` on its own means you need to press `return` - telnet should be configured to send it as CRLF.
-
-1. Create simplex message queue:
-
-```telnet
->
->
-> NEW 1234 -- 1234 is recipient's key
-
-
-IDS QuCLU4YxgS7wcPFA YB4CCATREHkaQcEh -- recipient and sender IDs for the queue
+```sh
+brew update
+brew install openssl
+echo 'PATH="/opt/homebrew/opt/openssl@3/bin:$PATH"' >> ~/.zprofile # or follow whatever instructions brew suggests
+. ~/.zprofile # or restart your terminal to start a new session
 ```
 
-2. Sender can send their "key" to the queue:
+Now `openssl version` should be saying "OpenSSL". You can now run `smp-server init` to initialize your SMP server.
 
-```telnet
-> -- no signature (just press enter)
-> YB4CCATREHkaQcEh -- sender ID for the queue
-> SEND :key abcd
+### SMP client library
 
-YB4CCATREHkaQcEh
-OK
+[SMP client](https://github.com/simplex-chat/simplexmq/blob/master/src/Simplex/Messaging/Client.hs) is a Haskell library to connect to SMP servers that allows to:
+
+- execute commands with a functional API.
+- receive messages and other notifications via STM queue.
+- automatically send keep-alive commands.
+
+### SMP agent
+
+[SMP agent library](https://github.com/simplex-chat/simplexmq/blob/master/src/Simplex/Messaging/Agent.hs) can be used to run SMP agent as part of another application and to communicate with the agent via STM queues, without serializing and parsing commands and responses.
+
+Haskell type [ACommand](https://github.com/simplex-chat/simplexmq/blob/master/src/Simplex/Messaging/Agent/Protocol.hs) represents SMP agent protocol to communicate via STM queues.
+
+See [simplex-chat](https://github.com/simplex-chat/simplex-chat) terminal UI for the example of integrating SMP agent into another application.
+
+[SMP agent executable](https://github.com/simplex-chat/simplexmq/blob/master/apps/smp-agent/Main.hs) can be used to run a standalone SMP agent process that implements plaintext [SMP agent protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md) via TCP port 5224, so it can be used via telnet. It can be deployed in private networks to share access to the connections between multiple applications and services.
+
+## Using SMP server and SMP agent
+
+You can either run your own SMP server locally or deploy using [Linode StackScript](https://cloud.linode.com/stackscripts/748014), or try local SMP agent with the deployed servers:
+
+`smp://u2dS9sG8nMNURyZwqASV4yROM28Er0luVTx5X1CsMrU=@smp4.simplex.im`
+
+`smp://hpq7_4gGJiilmz5Rf-CswuU5kZGkm_zOIooSw6yALRg=@smp5.simplex.im`
+
+`smp://PQUV2eL0t7OStZOoAsPEV2QYWt4-xilbakvGUGOItUo=@smp6.simplex.im`
+
+It's the easiest to try SMP agent via a prototype [simplex-chat](https://github.com/simplex-chat/simplex-chat) terminal UI.
+
+## Deploy SMP server on Linux
+
+You can run your SMP server as a Linux process, optionally using a service manager for booting and restarts.
+
+- For Ubuntu you can download a binary from [the latest release](https://github.com/simplex-chat/simplexmq/releases).
+
+  If you're using other Linux distribution and the binary is incompatible with it, you can build from source using [Haskell stack](https://docs.haskellstack.org/en/stable/README/):
+
+  ```shell
+  curl -sSL https://get.haskellstack.org/ | sh
+  ...
+  stack install
+  ```
+
+- Initialize SMP server with `smp-server init [-l] -n <fqdn>` or `smp-server init [-l] --ip <ip>` - depending on how you initialize it, either FQDN or IP will be used for server's address.
+
+- Run `smp-server start` to start SMP server, or you can configure a service manager to run it as a service.
+
+See [this section](#smp-server) for more information. Run `smp-server -h` and `smp-server init -h` for explanation of commands and options.
+
+[<img alt="Linode" src="https://raw.githubusercontent.com/simplex-chat/simplexmq/master/img/linode.svg" align="right" width="200">](https://cloud.linode.com/stackscripts/748014)
+
+## Deploy SMP server on Linode
+
+\* You can use free credit Linode offers when [creating a new account](https://www.linode.com/) to deploy an SMP server.
+
+Deployment on Linode is performed via StackScripts, which serve as recipes for Linode instances, also called Linodes. To deploy SMP server on Linode:
+
+- Create a Linode account or login with an already existing one.
+- Open [SMP server StackScript](https://cloud.linode.com/stackscripts/748014) and click "Deploy New Linode".
+- You can optionally configure the following parameters:
+  - SMP Server store log flag for queue persistence on server restart, recommended.
+  - [Linode API token](https://www.linode.com/docs/guides/getting-started-with-the-linode-api#get-an-access-token) to attach server address etc. as tags to Linode and to add A record to your 2nd level domain (e.g. `example.com` [domain should be created](https://cloud.linode.com/domains/create) in your account prior to deployment). The API token access scopes:
+    - read/write for "linodes"
+    - read/write for "domains"
+  - Domain name to use instead of Linode IP address, e.g. `smp1.example.com`.
+- Choose the region and plan, Shared CPU Nanode with 1Gb is sufficient.
+- Provide ssh key to be able to connect to your Linode via ssh. If you haven't provided a Linode API token this step is required to login to your Linode and get the server's fingerprint either from the welcome message or from the file `/etc/opt/simplex/fingerprint` after server starts. See [Linode's guide on ssh](https://www.linode.com/docs/guides/use-public-key-authentication-with-ssh/) .
+- Deploy your Linode. After it starts wait for SMP server to start and for tags to appear (if a Linode API token was provided). It may take up to 5 minutes depending on the connection speed on the Linode. Connecting Linode IP address to provided domain name may take some additional time.
+- Get `address` and `fingerprint` either from Linode tags (click on a tag and copy it's value from the browser search panel) or via ssh.
+- Great, your own SMP server is ready! If you provided FQDN use `smp://<fingerprint>@<fqdn>` as SMP server address in the client, otherwise use `smp://<fingerprint>@<ip_address>`.
+
+Please submit an [issue](https://github.com/simplex-chat/simplexmq/issues) if any problems occur.
+
+[<img alt="DigitalOcean" src="https://raw.githubusercontent.com/simplex-chat/simplexmq/master/img/digitalocean.png" align="right" width="300">](https://marketplace.digitalocean.com/apps/simplex-server)
+
+## Deploy SMP server on DigitalOcean
+
+> 🚧 DigitalOcean snapshot is currently not up to date, it will soon be updated 🏗️
+
+\* When creating a DigitalOcean account you can use [this link](https://try.digitalocean.com/freetrialoffer/) to get free credit. (You would still be required either to provide your credit card details or make a confirmation pre-payment with PayPal)
+
+To deploy SMP server use [SimpleX Server 1-click app](https://marketplace.digitalocean.com/apps/simplex-server) from DigitalOcean marketplace:
+
+- Create a DigitalOcean account or login with an already existing one.
+- Click 'Create SimpleX server Droplet' button.
+- Choose the region and plan according to your requirements (Basic plan should be sufficient).
+- Finalize Droplet creation.
+- Open "Console" on your Droplet management page to get SMP server fingerprint - either from the welcome message or from `/etc/opt/simplex/fingerprint`. Alternatively you can manually SSH to created Droplet, see [DigitalOcean instruction](https://docs.digitalocean.com/products/droplets/how-to/connect-with-ssh/).
+- Great, your own SMP server is ready! Use `smp://<fingerprint>@<ip_address>` as SMP server address in the client.
+
+Please submit an [issue](https://github.com/simplex-chat/simplexmq/issues) if any problems occur.
+
+> **Please note:** SMP server uses server address as a Common Name for server certificate generated during initialization. If you would like your server address to be FQDN instead of IP address, you can log in to your Droplet and run the commands below to re-initialize the server. Alternatively you can use [Linode StackScript](https://cloud.linode.com/stackscripts/748014) which allows this parameterization.
+
+```sh
+smp-server delete
+smp-server init [-l] -n <fqdn>
 ```
 
-3. Secure queue with sender's "key"
+## SMP server design
 
-```telnet
-> 1234 -- recipient's "signature" - same as "key" in the demo
-> QuCLU4YxgS7wcPFA -- recipient ID
-> KEY abcd -- "key" provided by sender
+![SMP server design](https://raw.githubusercontent.com/simplex-chat/simplexmq/master/design/server.svg)
 
-QuCLU4YxgS7wcPFA
-OK
-```
+## SMP agent design
 
-4. Sender can now send messages to the queue
+![SMP agent design](https://raw.githubusercontent.com/simplex-chat/simplexmq/master/design/agent2.svg)
 
-```telnet
-> abcd -- sender's "signature" - same as "key" in the demo
-> YB4CCATREHkaQcEh -- sender ID
-> SEND :hello
+## License
 
-YB4CCATREHkaQcEh
-OK
-```
-
-5. Recipient recieves the message and acknowledges it to receive further messages
-
-```telnet
-
-QuCLU4YxgS7wcPFA
-MSG ECA3w3ID 2020-10-18T20:19:36.874Z 5
-hello
-> 1234
-> QuCLU4YxgS7wcPFA
-> ACK
-
-QuCLU4YxgS7wcPFA
-OK
-```
-
-## Design
-
-![server design](design/server.svg)
+[AGPL v3](https://github.com/simplex-chat/simplexmq/blob/master/LICENSE)

apps/ntf-server/Main.hs

@@ -0,0 +1,74 @@
+{-# LANGUAGE NamedFieldPuns #-}
+
+module Main where
+
+import Control.Logger.Simple
+import Simplex.Messaging.Client.Agent (defaultSMPClientAgentConfig)
+import Simplex.Messaging.Notifications.Server (runNtfServer)
+import Simplex.Messaging.Notifications.Server.Env (NtfServerConfig (..))
+import Simplex.Messaging.Notifications.Server.Push.APNS (defaultAPNSPushClientConfig)
+import Simplex.Messaging.Server.CLI (ServerCLIConfig (..), protocolServerCLI)
+import System.FilePath (combine)
+
+cfgPath :: FilePath
+cfgPath = "/etc/opt/simplex-notifications"
+
+logPath :: FilePath
+logPath = "/var/opt/simplex-notifications"
+
+logCfg :: LogConfig
+logCfg = LogConfig {lc_file = Nothing, lc_stderr = True}
+
+main :: IO ()
+main = do
+  setLogLevel LogDebug -- change to LogError in production
+  withGlobalLogging logCfg $ protocolServerCLI ntfServerCLIConfig runNtfServer
+
+ntfServerCLIConfig :: ServerCLIConfig NtfServerConfig
+ntfServerCLIConfig =
+  let caCrtFile = combine cfgPath "ca.crt"
+      serverKeyFile = combine cfgPath "server.key"
+      serverCrtFile = combine cfgPath "server.crt"
+   in ServerCLIConfig
+        { cfgDir = cfgPath,
+          logDir = logPath,
+          iniFile = combine cfgPath "ntf-server.ini",
+          storeLogFile = combine logPath "ntf-server-store.log",
+          caKeyFile = combine cfgPath "ca.key",
+          caCrtFile,
+          serverKeyFile,
+          serverCrtFile,
+          fingerprintFile = combine cfgPath "fingerprint",
+          defaultServerPort = "443",
+          executableName = "ntf-server",
+          serverVersion = "SMP notifications server v0.1.0",
+          mkIniFile = \enableStoreLog defaultServerPort ->
+            "[STORE_LOG]\n\
+            \# The server uses STM memory for persistence,\n\
+            \# that will be lost on restart (e.g., as with redis).\n\
+            \# This option enables saving memory to append only log,\n\
+            \# and restoring it when the server is started.\n\
+            \# Log is compacted on start (deleted objects are removed).\n\
+            \# The messages are not logged.\n"
+              <> ("enable: " <> (if enableStoreLog then "on" else "off  # on") <> "\n\n")
+              <> "[TRANSPORT]\n\
+                 \port: "
+              <> defaultServerPort
+              <> "\n\
+                 \websockets: off\n",
+          mkServerConfig = \_storeLogFile transports _ ->
+            NtfServerConfig
+              { transports,
+                subIdBytes = 24,
+                regCodeBytes = 32,
+                clientQSize = 16,
+                subQSize = 64,
+                pushQSize = 128,
+                smpAgentCfg = defaultSMPClientAgentConfig,
+                apnsConfig = defaultAPNSPushClientConfig,
+                inactiveClientExpiration = Nothing,
+                caCertificateFile = caCrtFile,
+                privateKeyFile = serverKeyFile,
+                certificateFile = serverCrtFile
+              }
+        }

apps/smp-agent/Main.hs

@@ -0,0 +1,30 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
+module Main where
+
+import Control.Logger.Simple
+import qualified Data.List.NonEmpty as L
+import Simplex.Messaging.Agent.Env.SQLite
+import Simplex.Messaging.Agent.Server (runSMPAgent)
+import Simplex.Messaging.Transport (TLS, Transport (..))
+
+cfg :: AgentConfig
+cfg = defaultAgentConfig
+
+servers :: InitialAgentServers
+servers =
+  InitialAgentServers
+    { smp = L.fromList ["smp://bU0K-bRg24xWW__lS0umO1Zdw_SXqpJNtm1_RrPLViE=@localhost:5223"],
+      ntf = []
+    }
+
+logCfg :: LogConfig
+logCfg = LogConfig {lc_file = Nothing, lc_stderr = True}
+
+main :: IO ()
+main = do
+  putStrLn $ "SMP agent listening on port " ++ tcpPort (cfg :: AgentConfig)
+  setLogLevel LogInfo -- LogError
+  withGlobalLogging logCfg $ runSMPAgent (transport @TLS) cfg servers

apps/smp-server/Main.hs

@@ -1,18 +1,107 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE NumericUnderscores #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
 module Main where
 
-import Env.STM
-import Server (runSMPServer)
+import Control.Logger.Simple
+import Data.Functor (($>))
+import Data.Ini (lookupValue)
+import Simplex.Messaging.Server (runSMPServer)
+import Simplex.Messaging.Server.CLI (ServerCLIConfig (..), protocolServerCLI, readStrictIni)
+import Simplex.Messaging.Server.Env.STM (ServerConfig (..), defaultInactiveClientExpiration, defaultMessageExpiration)
+import Simplex.Messaging.Server.Expiration
+import Simplex.Messaging.Transport (simplexMQVersion)
+import System.FilePath (combine)
 
-cfg :: Config
-cfg =
-  Config
-    { tcpPort = "5223",
-      tbqSize = 16,
-      queueIdBytes = 12,
-      msgIdBytes = 6
-    }
+cfgPath :: FilePath
+cfgPath = "/etc/opt/simplex"
+
+logPath :: FilePath
+logPath = "/var/opt/simplex"
+
+logCfg :: LogConfig
+logCfg = LogConfig {lc_file = Nothing, lc_stderr = True}
 
 main :: IO ()
 main = do
-  putStrLn $ "Listening on port " ++ tcpPort cfg
-  runSMPServer cfg
+  setLogLevel LogInfo
+  withGlobalLogging logCfg . protocolServerCLI smpServerCLIConfig $ \cfg@ServerConfig {inactiveClientExpiration} -> do
+    putStrLn $ case inactiveClientExpiration of
+      Just ExpirationConfig {ttl, checkInterval} -> "expiring clients inactive for " <> show ttl <> " seconds every " <> show checkInterval <> " seconds"
+      _ -> "not expiring inactive clients"
+    runSMPServer cfg
+
+smpServerCLIConfig :: ServerCLIConfig ServerConfig
+smpServerCLIConfig =
+  let caCrtFile = combine cfgPath "ca.crt"
+      serverKeyFile = combine cfgPath "server.key"
+      serverCrtFile = combine cfgPath "server.crt"
+   in ServerCLIConfig
+        { cfgDir = cfgPath,
+          logDir = logPath,
+          iniFile = combine cfgPath "smp-server.ini",
+          storeLogFile = combine logPath "smp-server-store.log",
+          caKeyFile = combine cfgPath "ca.key",
+          caCrtFile,
+          serverKeyFile,
+          serverCrtFile,
+          fingerprintFile = combine cfgPath "fingerprint",
+          defaultServerPort = "5223",
+          executableName = "smp-server",
+          serverVersion = "SMP server v" <> simplexMQVersion,
+          mkIniFile = \enableStoreLog defaultServerPort ->
+            "[STORE_LOG]\n\
+            \# The server uses STM memory for persistence,\n\
+            \# that will be lost on restart (e.g., as with redis).\n\
+            \# This option enables saving memory to append only log,\n\
+            \# and restoring it when the server is started.\n\
+            \# Log is compacted on start (deleted objects are removed).\n"
+              <> ("enable: " <> (if enableStoreLog then "on" else "off  # on") <> "\n")
+              <> "# The messages are optionally saved and restored when the server restarts,\n\
+                 \# they are deleted after restarting.\n"
+              <> ("restore_messages: " <> (if enableStoreLog then "on" else "off  # on") <> "\n\n")
+              <> "[TRANSPORT]\n"
+              <> ("port: " <> defaultServerPort <> "\n")
+              <> "websockets: off\n\n"
+              <> "[INACTIVE_CLIENTS]\n\
+                 \# TTL and interval to check inactive clients\n\
+                 \disconnect: off\n"
+              <> ("# ttl: " <> show (ttl defaultInactiveClientExpiration) <> "\n")
+              <> ("# check_interval: " <> show (checkInterval defaultInactiveClientExpiration) <> "\n"),
+          mkServerConfig = \storeLogFile transports ini ->
+            ServerConfig
+              { transports,
+                tbqSize = 16,
+                serverTbqSize = 64,
+                msgQueueQuota = 128,
+                queueIdBytes = 24,
+                msgIdBytes = 24, -- must be at least 24 bytes, it is used as 192-bit nonce for XSalsa20
+                caCertificateFile = caCrtFile,
+                privateKeyFile = serverKeyFile,
+                certificateFile = serverCrtFile,
+                storeLogFile,
+                storeMsgsFile =
+                  let messagesPath = combine logPath "smp-server-messages.log"
+                   in case lookupValue "STORE_LOG" "restore_messages" ini of
+                        Right "on" -> Just messagesPath
+                        Right _ -> Nothing
+                        -- if the setting is not set, it is enabled when store log is enabled
+                        _ -> storeLogFile $> messagesPath,
+                allowNewQueues = True,
+                messageExpiration = Just defaultMessageExpiration,
+                inactiveClientExpiration =
+                  if lookupValue "INACTIVE_CLIENTS" "disconnect" ini == Right "on"
+                    then
+                      Just
+                        ExpirationConfig
+                          { ttl = readStrictIni "INACTIVE_CLIENTS" "ttl" ini,
+                            checkInterval = readStrictIni "INACTIVE_CLIENTS" "check_interval" ini
+                          }
+                    else Nothing,
+                logStatsInterval = Just 86400, -- seconds
+                logStatsStartTime = 0 -- seconds from 00:00 UTC
+              }
+        }

cabal.project

@@ -0,0 +1,6 @@
+packages: .
+
+source-repository-package
+    type: git
+    location: https://github.com/simplex-chat/aeson.git
+    tag: 3eb66f9a68f103b5f1489382aad89f5712a64db7

design/agent-commands.md

@@ -0,0 +1,185 @@
+# SMP agent commands (Duplex protocol commands) 
+
+This document describes Duplex commands flow through SMP agent components (see *design/agent.gv*), as well as some interactions between [recipient and sender](#Recipient-and-sender-terminology) clients, clients' SMP agents and SMP servers, and sequencing of Duplex and SMP commands.
+
+Legend:
+
+- > Command flow through SMP agent in blockquotes
+
+- **Q - Design and other questions in bold**
+
+## Table of contents
+
+- [Recipient and sender terminology](#Recipient-and-sender-terminology)
+- [Agent design comparison](#agent-design-comparison)
+- [Communication between user client and client-side SMP agent](#Communication-between-user-client-and-client-side-SMP-agent)
+  - [User client commands](#User-client-commands)
+    - [`create`](#create)
+    - [`join`](#join)
+    - [`accept`](#accept)
+    - [`subscribe`](#subscribe)
+    - [`getStatus`](#getStatus)
+    - [`send`](#send)
+    - [`acknowledge`](#acknowledge)
+    - [`suspend`](#suspend)
+    - [`delete`](#delete)
+  - [Agent messages to user client](#Agent-messages-to-user-client)
+    - [`connection`](#connection)
+    - [`connectionInvitation`](#connectionInvitation)
+    - [`confirmation`](#confirmation)
+    - [`message`](#message)
+    - [`unsubscribed`](#unsubscribed)
+    - [`queueStatus`](#queueStatus)
+    - [`ok`](#ok)
+    - [`error`](#error)
+- [Communication between SMP agents](#Communication-between-SMP-agents)
+  - [`helloMsg`](#helloMsg)
+  - [`replyQueueMsg`](#replyQueueMsg)
+  - [`deleteQueueMsg`](#deleteQueueMsg)
+  - [`clientMsg`](#clientMsg)
+  - [`acknowledgeMsg`](#acknowledgeMsg)
+- [General questions](#General-questions)
+
+## Recipient and sender terminology
+
+Here and further recipient is referred to the side that initiates the connection, i.e. creates the initial SMP queue and sends an out-of-band invitation to the sender. Sender is referred to the side that joins this SMP queue through the out-of-band invitation and then creates another SMP queue in the opposite direction for the recipient. This is to distinguish the sides for commands that imply specific direction, conceptually in Duplex connection once connection is established both sides act both as a recipient and a sender through different SMP queues.
+
+## Agent design comparison
+
+| Option | Pros | Cons |
+| ------ | ---- | ---- | 
+| agent.gv | one TCP connection to a specific SMP server host is re-used by multiple users. | responses from the same server to multiple users are mixed and have to be correlated not only with commands but with the users as well, this correlation is not present in the design yet |
+| agent2.gv | easier correlation of commands with responses, clear separation of internal user agent API (TBQueues) from TCP api (although this can be done with the first design as well) | if there are multiple users, there may be multiple TCP connections to the same SMP host |
+
+## Communication between user client and client-side SMP agent
+
+### User client commands
+
+#### `create`
+
+🚧 **To be fixed according to agent2.gv**
+
+Requests recipient SMP server to create a new SMP queue. 
+
+Is made by the [recipient](#Recipient-and-sender-terminology).
+
+> recipient user client -> user agent TCP socket (main socket) -> runUser thread -> create user connection group (socket and threads) -> user connection group "user" thread -> agent server commands queue -> runServer thread -> SMP `create` command sent to server connection group "send" queue -> server connection group "send" thread -> SMP server connection TCP socket -> recipient's SMP server
+
+- SMP Server then responds with SMP `queueIds` command to SMP server connection TCP socket
+- Recipient agent gets automatically subscribed to receive the messages from the queue
+- Agent replies to user client with Duplex [`connectionInvitation`](#connectionInvitation) command
+- User sends connection invitation out-of-band to sender
+
+- **Q - Shouldn't user connection group be created after server responds, or even after sender joins and invites back?**
+
+  A - Agent has to correlate commands with responses anyway (replying on the fact that responses arrive in the same order that the commands were sent, occasionally interleaved with messages), so all the information needed to create the connection will be available in the command buffer anyway. It is probably better to create connection in the agent after the queue was successfully created in the server, and send an error to the user if SMP server responded with error.
+
+- **Q - How does flow go from runUser thread to user connection group "user" thread? Does runUser pass the the initial `create` command further to "user" thread through socket?**
+
+  A - runUser does not receive any TCP traffic other than initial TCP handshake, when it does it forks all user group threads. It does not participate in commands/messages flow. Commands go from "user" to "runServer" (via TBQueue), responses,messages and acknowledgements (see protocol changes) from "message subscriber" to "send" (via TBQueue)
+
+- **Q - Does sender agent persist partial info about connection record at this point, or only when receives an opposing queue from the sender?**
+
+  A - Yes, it should create connection with one queue (status "PENDING"), the status of the second queue will be "NONE" - see sequence diagram. In types it is `Maybe ConnState` with "NONE" corresponding to `Nothing`, as we don't need to have the second queue record. Also, protocol allows not to have reply queue, so the connection can remain unidirectional.
+
+- **Q - Shouldn't agent at this point answer with Duplex [`connection`](#connection) command? SMP agent commands have conflicting comments in the Duplex protocol. What is that command used for at all at this point?**
+
+  A - There is no need to split creating connection and creating the invitation - it was initially two commands, and now it's merged into one - it creates the queue on SMP server, connection record in the agent and the invitation string to be sent out-of-band to the other party - need to fix any contradictions.
+
+#### `join`
+
+🚧 **To be fixed according to agent2.gv**
+
+Replies via out-of-band invitation with sender's key and profile.
+
+Is made by the [sender](#Recipient-and-sender-terminology).
+
+> sender user client -> user agent TCP socket (main socket) -> runUser thread -> create user connection group (socket and threads) -> user connection group "user" thread -> agent server commands queue -> runServer thread -> SMP `send` command sent to server connection group "send" queue, it contains sender's key and profile wrapped in Duplex [`clientMsg`](#clientMsg) command -> server connection group "send" thread -> SMP server connection TCP socket -> recipient's SMP server
+
+- SMP server then delivers sender's message containing key and profile to recipient SMP agent with SMP `message` command
+- Recipient agent secures previously created queue with Duplex [`accept`](#accept) command
+
+#### `accept`
+
+🚧 **To be fixed according to agent2.gv**
+
+Secures SMP queue with sender's key.
+
+Is made by the [recipient](#Recipient-and-sender-terminology).
+
+> recipient user client -> user connection TCP socket -> user connection group "user" thread -> agent server commands queue -> runServer thread -> SMP `secure` command sent to server connection group "send" queue -> server connection group "send" thread -> SMP server connection TCP socket -> recipient's SMP server
+
+- Sender's agent at this point repeatedly sends Duplex [`helloMsg`](#helloMsg) command to the recipient SMP server, which should be successful once sender queue is secured by the recipient agent with key provided by the sender in the Duplex [`join`](#join) command
+- **Q - Does this command go through user agent TCP socket (main socket)? This relates to the question whether user connection groups for the recipient agent should be created during Duplex [`create`](#create) command**
+
+  A - User connection group is created during TCP handshake.
+
+#### `subscribe`
+
+Subscribes/unsubscribes user to/from SMP queue.
+
+> agent client -> user connection TCP socket -> "user receive" thread -> user receive TBQueue -> "process commands" thread -> \*
+>
+> \* -> commands TBQueue -> client thread; client thread is blocked until receives answer from SMP server -> \#
+>
+> \* -> srv snd TBQueue -> "server send" thread -> `subscribe` SMP command is sent through SMP client connection TCP socket -> SMP server responds with first available message or if there is none with SMP `ok` command back to SMP client connection TCP socket -> "server receive" thread -> srv rcv TBQueue -> client thread; client thread becomes unblocked -> \#
+>
+> \# -> user SMP TBQueue -> "process responses" thread -> queue is persisted as Disabled -> Duplex [`ok`](#ok) command sent to user send TBQueue -> "user send" thread -> user connection TCP socket -> agent client
+
+- **Q - Which SMP command is sent to the SMP server on Duplex `subscribe Off`?**
+
+  A -
+
+#### `getStatus`
+
+#### `send`
+
+#### `acknowledge`
+
+#### `suspend`
+
+#### `delete`
+
+### Agent messages to user client
+
+TODO
+
+#### `connection`
+
+#### `connectionInvitation`
+
+#### `confirmation`
+
+#### `message`
+
+#### `unsubscribed`
+
+#### `queueStatus`
+
+#### `ok`
+
+#### `error`
+
+## Communication between SMP agents
+
+TODO
+
+#### `helloMsg`
+
+#### `replyQueueMsg`
+
+#### `deleteQueueMsg`
+
+#### `clientMsg`
+
+#### `acknowledgeMsg`
+
+## General questions
+
+- **Q - When does agent set up server connection groups?**
+
+  A - When it sees the new hostname:port combination - see the map of servers inside [AgentClient](https://github.com/simplex-chat/simplex-messaging/blob/client/src/Simplex/Messaging/Agent/Env.hs#L33)
+
+- **Q - Replace command keywords with command names in the Duplex protocol sequence diagram?**
+
+  A - Let's keep keywords, I also use them as constructors in code, they are part of the actual command syntax.

design/agent.gv

@@ -0,0 +1,79 @@
+digraph SMPAgent {
+  graph [fontname=arial]
+  node [fontname=arial fontsize=11 shape=box]
+  edge [fontname=arial fontsize=10 arrowhead=open arrowtail=open]
+
+  subgraph clusterAgent {
+    label="agent threads" 
+    main [shape=hexagon color=orange label="main\nthread"]
+    aSock [label="user agent TCP socket" color=darkgreen]
+    subgraph clusterThreads {
+      label="" 
+      node [shape=hexagon color=orange]
+      runUser [label="runUser\nthread"]
+      runServer [label="runServer\nthread"]
+      msgSubscriber [label="message\nsubscriber\nthread"]
+    }
+    main -> {runUser runServer} [style=dashed label=race color=orange fontcolor=orange]
+    aSock -> runUser [color=darkgreen]
+
+    acInq [shape=larrow label="agent\nserver\ncommands\nTBQueue"]
+    acInq -> runServer [color=darkgreen]
+    runServer -> amInq [color=darkgreen label="unknown\nconnection\nor\nwrong\nconnection\nstate"]
+
+    amInq [shape=rarrow label="agent\nserver\nmessages\nTBQueue"]
+    amInq -> msgSubscriber [color=blue]
+
+    msgSubscriber -> connectionsStore [dir=both]
+    runUser -> connectionsStore [dir=both]
+    runServer -> connectionsStore [dir=both]
+
+    connectionsStore [shape=cylinder label="duplex\nconnection\nrecords"]
+  }
+
+  subgraph clusterUser {
+    label="1 group per user connection"
+    uSock [label="user connection TCP socket" color=darkgreen]
+
+    subgraph clusterUserThreads {
+      graph [fontsize=11]
+      label="user threads"
+      node [shape=hexagon, color=orange]
+      uAgent [label="user"]
+      uSnd [label="send"]
+    }
+
+    runUser -> uSock [style=dashed label="connect" color=darkgreen fontcolor=darkgreen]
+    runUser -> {uAgent uSnd} [style=dashed label=race color=orange fontcolor=orange]
+
+    uOutq [shape=larrow label="send\nTBQueue"]
+    uSock -> uAgent [color=darkgreen]
+    uAgent -> uOutq [color=darkgreen label="SMAP\ncommand\nsyntax\nerror"]
+    uOutq -> uSnd -> uSock [color=darkgreen]
+
+    msgSubscriber -> uOutq [color=blue label="SMAP\nmessages\nand\ncommand\nresponses"]
+    uAgent -> acInq [color=darkgreen label="SMAP\nprotocol\ncommand"]
+  }
+
+  subgraph clusterServer {
+    label="1 group per SMP server connection"
+    sSock [label="SMP server connection TCP socket" color=blue]
+
+    subgraph clusterServerThreads {
+      graph [fontsize=11]
+      label="server threads"
+      node [shape=hexagon, color=orange]
+      sAgent [label="server"]
+      sSnd [label="send"]
+    }
+
+    runServer -> {sAgent sSnd} [style=dashed label=race color=orange fontcolor=orange]
+
+    sOutq [shape=larrow label="send\nTBQueue"]
+    sSock -> sAgent [color=blue]
+    runServer -> sOutq [color=darkgreen label="SMP\nprotocol\ncommand"]
+    sOutq -> sSnd -> sSock [color=blue]
+
+    sAgent -> amInq [color=blue label="wrapped\nSMP\nmessages\nand\ncommand\nresponses"]
+  }
+}

design/agent2.gv

@@ -0,0 +1,99 @@
+digraph SMPAgent {
+  graph [fontname=arial]
+  node [fontname=arial fontsize=11 shape=box]
+  edge [fontname=arial fontsize=10 arrowhead=open arrowtail=open]
+
+  main [shape=hexagon color=orange label="main\nthread"]
+  aSock [label="user agent TCP socket" color=darkgreen]
+
+  subgraph clusterPersistence {
+    graph [fontsize=11 color=gray]
+    label="persistence (sqlite)"
+    connectionsStore [shape=cylinder label="duplex connections,\nSMP queues,\nrecent messages"]
+  }
+
+  subgraph clusterAgent {
+    graph [color=gray]
+    node [shape=hexagon color=orange]
+    label="agent threads" 
+    connectClnt
+    runClnt
+  }
+
+  main -> {runClnt connectClnt} [style=dashed label="race" color=orange fontcolor=orange]
+  aSock -> connectClnt [color=darkgreen]
+
+  subgraph clusterUserTCP {
+    graph [color=gray]
+    label="1 group per user TCP connection"
+    uSock [label="user connection TCP socket" color=darkgreen]
+
+    subgraph clusterUserTCPThreads {
+      graph [fontsize=11 color=gray]
+      label="user TCP threads"
+      node [shape=hexagon, color=orange]
+      uRcv [label="user\nreceive"]
+      uSnd [label="user\nsend"]
+    }
+
+    uSock -> uRcv [color=darkgreen]
+    uSnd -> uSock [color=darkgreen]
+  }
+
+  subgraph clusterUser {
+    graph [color=gray]
+    label="1 group per user TCP connection"
+
+    subgraph clusterUserInterface {
+      graph [fontsize=11]
+      label="user queues"
+      uInq [shape=rarrow label="user\nreceive\nTBQueue"]
+      uOutq [shape=larrow label="user\nsend\nTBQueue"]
+    }
+
+    subgraph clusterUserThreads {
+      graph [fontsize=11]
+      label="user threads\nNote: `user agent` sends\nall commands to `commands TBQueue`s\n(invalid commands with attached responses),\nand only valid commands to `server TBQueue`.\nIt is used to respond in correct order."
+      node [shape=hexagon, color=orange]
+      uAgent [label="user\nagent"]
+      uProcess [label="process\nresponses"]
+    }
+
+    uRcv -> uInq -> uAgent [color=darkgreen]
+    uProcess -> uOutq -> uSnd [color=darkgreen]
+    {uRcv uAgent} -> uOutq [color=green]
+
+    uRespq [shape=rarrow label="user\nSMP\nTBQueue"]
+
+    subgraph clusterClient {
+      label="1 group per SMP client/server connection"
+      runClient [shape=hexagon, color=orange]
+      sOutq [shape=rarrow label="srv send\nTBQueue"]
+      sSock [label="SMP client connection TCP socket" color=blue]
+
+      subgraph clusterServerThreads {
+        graph [fontsize=11]
+        label="SMP client threads"
+        node [shape=hexagon, color=orange]
+        sAgent [label="server\nreceive"]
+        sSnd [label="server\nsend"]
+      }
+
+      runClient -> {sAgent sSnd} [style=dashed label=race color=orange fontcolor=orange]
+      {uAgent uProcess} -> sOutq -> sSnd -> sSock -> sAgent [color=blue]
+    }
+
+    userState [label="connected\nservers,\nsubscribed\nqueues,\nsent\ncommands\n(STM)" shape="folder"]
+
+    {uAgent uProcess} -> userState [dir=both color="#FF8888"]
+    {uAgent uProcess} -> connectionsStore [dir=both color="#880000"]
+
+    connectClnt -> uSock [style=dashed label="connect" color=darkgreen fontcolor=darkgreen]
+    connectClnt -> {uRcv uSnd} [style=dashed label="race" color=orange fontcolor=orange]
+    runClnt -> {uAgent uProcess} [style=dashed label="race" color=orange fontcolor=orange]
+
+    sAgent -> uRespq -> uProcess
+
+    uAgent -> runClient [style=dashed label="fork" color=orange fontcolor=orange]
+  }
+}

design/agent2.svg

@@ -0,0 +1,394 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 2.40.1 (20161225.0304)
+ -->
+<!-- Title: SMPAgent Pages: 1 -->
+<svg width="1073pt" height="1142pt"
+ viewBox="0.00 0.00 1073.00 1142.34" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 1138.3374)">
+<title>SMPAgent</title>
+<polygon fill="#ffffff" stroke="transparent" points="-4,4 -4,-1138.3374 1069,-1138.3374 1069,4 -4,4"/>
+<g id="clust1" class="cluster">
+<title>clusterPersistence</title>
+<polygon fill="none" stroke="#c0c0c0" points="927,-512.7374 927,-615.3874 1057,-615.3874 1057,-512.7374 927,-512.7374"/>
+<text text-anchor="middle" x="992" y="-601.4874" font-family="arial" font-size="11.00" fill="#000000">persistence (sqlite)</text>
+</g>
+<g id="clust2" class="cluster">
+<title>clusterAgent</title>
+<polygon fill="none" stroke="#c0c0c0" points="175,-963.3624 175,-1040.1624 389,-1040.1624 389,-963.3624 175,-963.3624"/>
+<text text-anchor="middle" x="282" y="-1023.5624" font-family="arial" font-size="14.00" fill="#000000">agent threads</text>
+</g>
+<g id="clust4" class="cluster">
+<title>clusterUserTCP</title>
+<polygon fill="none" stroke="#c0c0c0" points="8,-509.375 8,-933.3624 230,-933.3624 230,-509.375 8,-509.375"/>
+<text text-anchor="middle" x="119" y="-916.7624" font-family="arial" font-size="14.00" fill="#000000">1 group per user TCP connection</text>
+</g>
+<g id="clust5" class="cluster">
+<title>clusterUserTCPThreads</title>
+<polygon fill="none" stroke="#c0c0c0" points="38,-517.375 38,-610.7499 222,-610.7499 222,-517.375 38,-517.375"/>
+<text text-anchor="middle" x="130" y="-596.8499" font-family="arial" font-size="11.00" fill="#000000">user TCP threads</text>
+</g>
+<g id="clust6" class="cluster">
+<title>clusterUser</title>
+<polygon fill="none" stroke="#c0c0c0" points="250,-8 250,-826.5624 919,-826.5624 919,-8 250,-8"/>
+<text text-anchor="middle" x="584.5" y="-809.9624" font-family="arial" font-size="14.00" fill="#000000">1 group per user TCP connection</text>
+</g>
+<g id="clust7" class="cluster">
+<title>clusterUserInterface</title>
+<polygon fill="none" stroke="#c0c0c0" points="258,-400.375 258,-485.175 419,-485.175 419,-400.375 258,-400.375"/>
+<text text-anchor="middle" x="338.5" y="-471.275" font-family="arial" font-size="11.00" fill="#000000">user queues</text>
+</g>
+<g id="clust8" class="cluster">
+<title>clusterUserThreads</title>
+<polygon fill="none" stroke="#c0c0c0" points="622,-634.3874 622,-793.7624 865,-793.7624 865,-634.3874 622,-634.3874"/>
+<text text-anchor="middle" x="743.5" y="-779.8624" font-family="arial" font-size="11.00" fill="#000000">user threads</text>
+<text text-anchor="middle" x="743.5" y="-766.6624" font-family="arial" font-size="11.00" fill="#000000">Note: `user agent` sends</text>
+<text text-anchor="middle" x="743.5" y="-753.4624" font-family="arial" font-size="11.00" fill="#000000">all commands to `commands TBQueue`s</text>
+<text text-anchor="middle" x="743.5" y="-740.2624" font-family="arial" font-size="11.00" fill="#000000">(invalid commands with attached responses),</text>
+<text text-anchor="middle" x="743.5" y="-727.0624" font-family="arial" font-size="11.00" fill="#000000">and only valid commands to `server TBQueue`.</text>
+<text text-anchor="middle" x="743.5" y="-713.8624" font-family="arial" font-size="11.00" fill="#000000">It is used to respond in correct order.</text>
+</g>
+<g id="clust10" class="cluster">
+<title>clusterClient</title>
+<polygon fill="none" stroke="#c0c0c0" points="427,-128.6 427,-482.975 812,-482.975 812,-128.6 427,-128.6"/>
+<text text-anchor="middle" x="619.5" y="-466.375" font-family="arial" font-size="14.00" fill="#000000">1 group per SMP client/server connection</text>
+</g>
+<g id="clust11" class="cluster">
+<title>clusterServerThreads</title>
+<polygon fill="none" stroke="#c0c0c0" points="564,-136.6 564,-229.975 758,-229.975 758,-136.6 564,-136.6"/>
+<text text-anchor="middle" x="661" y="-216.075" font-family="arial" font-size="11.00" fill="#000000">SMP client threads</text>
+</g>
+<!-- main -->
+<g id="node1" class="node">
+<title>main</title>
+<polygon fill="none" stroke="#ffa500" points="382.542,-1106.2499 363.271,-1134.4251 324.729,-1134.4251 305.458,-1106.2499 324.729,-1078.0747 363.271,-1078.0747 382.542,-1106.2499"/>
+<text text-anchor="middle" x="344" y="-1109.5499" font-family="arial" font-size="11.00" fill="#000000">main</text>
+<text text-anchor="middle" x="344" y="-1096.3499" font-family="arial" font-size="11.00" fill="#000000">thread</text>
+</g>
+<!-- connectClnt -->
+<g id="node4" class="node">
+<title>connectClnt</title>
+<polygon fill="none" stroke="#ffa500" points="288.8246,-989.3624 262.4123,-1007.3624 209.5877,-1007.3624 183.1754,-989.3624 209.5877,-971.3624 262.4123,-971.3624 288.8246,-989.3624"/>
+<text text-anchor="middle" x="236" y="-986.0624" font-family="arial" font-size="11.00" fill="#000000">connectClnt</text>
+</g>
+<!-- main&#45;&gt;connectClnt -->
+<g id="edge1" class="edge">
+<title>main&#45;&gt;connectClnt</title>
+<path fill="none" stroke="#ffa500" stroke-dasharray="5,2" d="M321.6223,-1082.0307C303.5136,-1062.4318 278.0793,-1034.9044 259.6406,-1014.9484"/>
+<polygon fill="#ffa500" stroke="#ffa500" points="252.7011,-1007.4378 262.7926,-1011.7288 256.0942,-1011.1102 259.4874,-1014.7826 259.4874,-1014.7826 259.4874,-1014.7826 256.0942,-1011.1102 256.1823,-1017.8365 252.7011,-1007.4378 252.7011,-1007.4378"/>
+<text text-anchor="middle" x="308.7235" y="-1051.1624" font-family="arial" font-size="10.00" fill="#ffa500">race</text>
+</g>
+<!-- runClnt -->
+<g id="node5" class="node">
+<title>runClnt</title>
+<polygon fill="none" stroke="#ffa500" points="380.5019,-989.3624 362.251,-1007.3624 325.749,-1007.3624 307.4981,-989.3624 325.749,-971.3624 362.251,-971.3624 380.5019,-989.3624"/>
+<text text-anchor="middle" x="344" y="-986.0624" font-family="arial" font-size="11.00" fill="#000000">runClnt</text>
+</g>
+<!-- main&#45;&gt;runClnt -->
+<g id="edge2" class="edge">
+<title>main&#45;&gt;runClnt</title>
+<path fill="none" stroke="#ffa500" stroke-dasharray="5,2" d="M344,-1077.9547C344,-1059.6552 344,-1035.9253 344,-1017.631"/>
+<polygon fill="#ffa500" stroke="#ffa500" points="344,-1007.5699 348.5001,-1017.5699 344,-1012.5699 344.0001,-1017.5699 344.0001,-1017.5699 344.0001,-1017.5699 344,-1012.5699 339.5001,-1017.57 344,-1007.5699 344,-1007.5699"/>
+<text text-anchor="middle" x="353.7235" y="-1051.1624" font-family="arial" font-size="10.00" fill="#ffa500">race</text>
+</g>
+<!-- aSock -->
+<g id="node2" class="node">
+<title>aSock</title>
+<polygon fill="none" stroke="#006400" points="287.8624,-1124.2499 160.1376,-1124.2499 160.1376,-1088.2499 287.8624,-1088.2499 287.8624,-1124.2499"/>
+<text text-anchor="middle" x="224" y="-1102.9499" font-family="arial" font-size="11.00" fill="#000000">user agent TCP socket</text>
+</g>
+<!-- aSock&#45;&gt;connectClnt -->
+<g id="edge3" class="edge">
+<title>aSock&#45;&gt;connectClnt</title>
+<path fill="none" stroke="#006400" d="M225.8487,-1088.2424C227.781,-1069.421 230.8399,-1039.6253 233.0952,-1017.6565"/>
+<polygon fill="#006400" stroke="#006400" points="234.1294,-1007.583 237.5845,-1017.9903 233.6188,-1012.5568 233.1081,-1017.5307 233.1081,-1017.5307 233.1081,-1017.5307 233.6188,-1012.5568 228.6316,-1017.0711 234.1294,-1007.583 234.1294,-1007.583"/>
+</g>
+<!-- connectionsStore -->
+<g id="node3" class="node">
+<title>connectionsStore</title>
+<path fill="none" stroke="#000000" d="M1048.7017,-580.4228C1048.7017,-583.7287 1023.2871,-586.414 992,-586.414 960.7129,-586.414 935.2983,-583.7287 935.2983,-580.4228 935.2983,-580.4228 935.2983,-526.5021 935.2983,-526.5021 935.2983,-523.1962 960.7129,-520.5109 992,-520.5109 1023.2871,-520.5109 1048.7017,-523.1962 1048.7017,-526.5021 1048.7017,-526.5021 1048.7017,-580.4228 1048.7017,-580.4228"/>
+<path fill="none" stroke="#000000" d="M1048.7017,-580.4228C1048.7017,-577.117 1023.2871,-574.4316 992,-574.4316 960.7129,-574.4316 935.2983,-577.117 935.2983,-580.4228"/>
+<text text-anchor="middle" x="992" y="-563.3624" font-family="arial" font-size="11.00" fill="#000000">duplex connections,</text>
+<text text-anchor="middle" x="992" y="-550.1624" font-family="arial" font-size="11.00" fill="#000000">SMP queues,</text>
+<text text-anchor="middle" x="992" y="-536.9624" font-family="arial" font-size="11.00" fill="#000000">recent messages</text>
+</g>
+<!-- uSock -->
+<g id="node6" class="node">
+<title>uSock</title>
+<polygon fill="none" stroke="#006400" points="169.5337,-900.5624 16.4663,-900.5624 16.4663,-864.5624 169.5337,-864.5624 169.5337,-900.5624"/>
+<text text-anchor="middle" x="93" y="-879.2624" font-family="arial" font-size="11.00" fill="#000000">user connection TCP socket</text>
+</g>
+<!-- connectClnt&#45;&gt;uSock -->
+<g id="edge23" class="edge">
+<title>connectClnt&#45;&gt;uSock</title>
+<path fill="none" stroke="#006400" stroke-dasharray="5,2" d="M198.6778,-978.637C182.4066,-972.8176 163.7253,-964.4984 148.985,-953.3624 133.1431,-941.3941 119.2685,-923.9297 109.2945,-909.3413"/>
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+<text text-anchor="middle" x="165.5075" y="-944.3624" font-family="arial" font-size="10.00" fill="#006400">connect</text>
+</g>
+<!-- uRcv -->
+<g id="node7" class="node">
+<title>uRcv</title>
+<polygon fill="none" stroke="#ffa500" points="214.0134,-553.4624 193.0067,-581.6377 150.9933,-581.6377 129.9866,-553.4624 150.9933,-525.2872 193.0067,-525.2872 214.0134,-553.4624"/>
+<text text-anchor="middle" x="172" y="-556.7624" font-family="arial" font-size="11.00" fill="#000000">user</text>
+<text text-anchor="middle" x="172" y="-543.5624" font-family="arial" font-size="11.00" fill="#000000">receive</text>
+</g>
+<!-- connectClnt&#45;&gt;uRcv -->
+<g id="edge24" class="edge">
+<title>connectClnt&#45;&gt;uRcv</title>
+<path fill="none" stroke="#ffa500" stroke-dasharray="5,2" d="M237.1238,-971.0203C239.9206,-916.7089 244.541,-752.4513 208,-623.3874 204.8674,-612.323 199.8997,-600.9707 194.6434,-590.7174"/>
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+<text text-anchor="middle" x="247.7235" y="-837.5624" font-family="arial" font-size="10.00" fill="#ffa500">race</text>
+</g>
+<!-- uSnd -->
+<g id="node8" class="node">
+<title>uSnd</title>
+<polygon fill="none" stroke="#ffa500" points="111.5662,-553.4624 95.2831,-581.6377 62.7169,-581.6377 46.4338,-553.4624 62.7169,-525.2872 95.2831,-525.2872 111.5662,-553.4624"/>
+<text text-anchor="middle" x="79" y="-556.7624" font-family="arial" font-size="11.00" fill="#000000">user</text>
+<text text-anchor="middle" x="79" y="-543.5624" font-family="arial" font-size="11.00" fill="#000000">send</text>
+</g>
+<!-- connectClnt&#45;&gt;uSnd -->
+<g id="edge25" class="edge">
+<title>connectClnt&#45;&gt;uSnd</title>
+<path fill="none" stroke="#ffa500" stroke-dasharray="5,2" d="M232.6954,-971.3264C227.2453,-941.3316 216.1632,-879.2768 208,-826.5624 201.0253,-781.5225 212.2627,-655.5799 180,-623.3874 161.268,-604.6963 143.493,-629.327 121,-615.3874 111.1934,-609.31 103.1361,-599.9964 96.7947,-590.4234"/>
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+<text text-anchor="middle" x="219.7235" y="-837.5624" font-family="arial" font-size="10.00" fill="#ffa500">race</text>
+</g>
+<!-- uAgent -->
+<g id="node11" class="node">
+<title>uAgent</title>
+<polygon fill="none" stroke="#ffa500" points="715.5622,-670.4749 697.7811,-698.6502 662.2189,-698.6502 644.4378,-670.4749 662.2189,-642.2997 697.7811,-642.2997 715.5622,-670.4749"/>
+<text text-anchor="middle" x="680" y="-673.7749" font-family="arial" font-size="11.00" fill="#000000">user</text>
+<text text-anchor="middle" x="680" y="-660.5749" font-family="arial" font-size="11.00" fill="#000000">agent</text>
+</g>
+<!-- runClnt&#45;&gt;uAgent -->
+<g id="edge26" class="edge">
+<title>runClnt&#45;&gt;uAgent</title>
+<path fill="none" stroke="#ffa500" stroke-dasharray="5,2" d="M363.0275,-971.304C418.9032,-918.2741 582.8091,-762.7159 650.3686,-698.5972"/>
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+<text text-anchor="middle" x="482.7235" y="-879.5624" font-family="arial" font-size="10.00" fill="#ffa500">race</text>
+</g>
+<!-- uProcess -->
+<g id="node12" class="node">
+<title>uProcess</title>
+<polygon fill="none" stroke="#ffa500" points="849.4801,-670.4749 822.24,-698.6502 767.76,-698.6502 740.5199,-670.4749 767.76,-642.2997 822.24,-642.2997 849.4801,-670.4749"/>
+<text text-anchor="middle" x="795" y="-673.7749" font-family="arial" font-size="11.00" fill="#000000">process</text>
+<text text-anchor="middle" x="795" y="-660.5749" font-family="arial" font-size="11.00" fill="#000000">responses</text>
+</g>
+<!-- runClnt&#45;&gt;uProcess -->
+<g id="edge27" class="edge">
+<title>runClnt&#45;&gt;uProcess</title>
+<path fill="none" stroke="#ffa500" stroke-dasharray="5,2" d="M375.4171,-984.2599C446.9624,-971.0733 623.6511,-929.4235 725,-826.5624 757.4412,-793.6372 776.3095,-743.0546 786.1177,-708.4539"/>
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+<text text-anchor="middle" x="686.7235" y="-879.5624" font-family="arial" font-size="10.00" fill="#ffa500">race</text>
+</g>
+<!-- uSock&#45;&gt;uRcv -->
+<g id="edge4" class="edge">
+<title>uSock&#45;&gt;uRcv</title>
+<path fill="none" stroke="#006400" d="M97.3599,-864.3998C109.8154,-812.5125 145.7537,-662.8 162.808,-591.7545"/>
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+</g>
+<!-- uInq -->
+<g id="node9" class="node">
+<title>uInq</title>
+<polygon fill="none" stroke="#000000" points="392.5723,-449.7766 347.4277,-449.7766 347.4277,-414.5733 392.5723,-414.5733 392.5723,-408.5733 410.5723,-432.175 392.5723,-455.7766 392.5723,-449.7766"/>
+<text text-anchor="middle" x="379" y="-442.075" font-family="arial" font-size="11.00" fill="#000000">user</text>
+<text text-anchor="middle" x="379" y="-428.875" font-family="arial" font-size="11.00" fill="#000000">receive</text>
+<text text-anchor="middle" x="379" y="-415.675" font-family="arial" font-size="11.00" fill="#000000">TBQueue</text>
+</g>
+<!-- uRcv&#45;&gt;uInq -->
+<g id="edge6" class="edge">
+<title>uRcv&#45;&gt;uInq</title>
+<path fill="none" stroke="#006400" d="M207.752,-544.8492C243.6388,-534.9021 299.1678,-515.8485 339,-485.175 346.5794,-479.3383 353.4481,-471.7165 359.2704,-464.0802"/>
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+</g>
+<!-- uOutq -->
+<g id="node10" class="node">
+<title>uOutq</title>
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+<text text-anchor="middle" x="298" y="-415.675" font-family="arial" font-size="11.00" fill="#000000">TBQueue</text>
+</g>
+<!-- uRcv&#45;&gt;uOutq -->
+<g id="edge10" class="edge">
+<title>uRcv&#45;&gt;uOutq</title>
+<path fill="none" stroke="#00ff00" d="M196.5932,-529.7891C216.4531,-510.6719 244.5472,-483.6285 266.1304,-462.8527"/>
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+</g>
+<!-- uSnd&#45;&gt;uSock -->
+<g id="edge5" class="edge">
+<title>uSnd&#45;&gt;uSock</title>
+<path fill="none" stroke="#006400" d="M80.2082,-581.8642C82.8558,-644.1008 89.1434,-791.9036 91.7913,-854.15"/>
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+</g>
+<!-- uInq&#45;&gt;uAgent -->
+<g id="edge7" class="edge">
+<title>uInq&#45;&gt;uAgent</title>
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+<!-- uOutq&#45;&gt;uSnd -->
+<g id="edge9" class="edge">
+<title>uOutq&#45;&gt;uSnd</title>
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+<!-- uAgent&#45;&gt;connectionsStore -->
+<g id="edge21" class="edge">
+<title>uAgent&#45;&gt;connectionsStore</title>
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+<!-- uAgent&#45;&gt;uOutq -->
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+<title>uAgent&#45;&gt;uOutq</title>
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+<!-- runClient -->
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+<!-- uAgent&#45;&gt;runClient -->
+<g id="edge30" class="edge">
+<title>uAgent&#45;&gt;runClient</title>
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+<!-- sOutq -->
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+<title>sOutq</title>
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+<text text-anchor="middle" x="772" y="-422.275" font-family="arial" font-size="11.00" fill="#000000">TBQueue</text>
+</g>
+<!-- uAgent&#45;&gt;sOutq -->
+<g id="edge14" class="edge">
+<title>uAgent&#45;&gt;sOutq</title>
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+<!-- uAgent&#45;&gt;userState -->
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+<title>uAgent&#45;&gt;userState</title>
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+<!-- uProcess&#45;&gt;connectionsStore -->
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+<title>uProcess&#45;&gt;connectionsStore</title>
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+<!-- uProcess&#45;&gt;uOutq -->
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+<title>uProcess&#45;&gt;uOutq</title>
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+<!-- uProcess&#45;&gt;sOutq -->
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+<title>uProcess&#45;&gt;sOutq</title>
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+<title>uProcess&#45;&gt;userState</title>
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+<!-- uRespq&#45;&gt;uProcess -->
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+<!-- sOutq&#45;&gt;sSnd -->
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package.yaml

@@ -1,29 +1,85 @@
-name: simplex-messaging
-version: 0.1.0.0
-#synopsis:
-#description:
-homepage: https://github.com/simplex-chat/simplex-messaging#readme
+name: simplexmq
+version: 2.3.0
+synopsis: SimpleXMQ message broker
+description: |
+  This package includes <./docs/Simplex-Messaging-Server.html server>,
+  <./docs/Simplex-Messaging-Client.html client> and
+  <./docs/Simplex-Messaging-Agent.html agent> for SMP protocols:
+  .
+  * <https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md SMP protocol>
+  * <https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md SMP agent protocol>
+  .
+  See <https://github.com/simplex-chat/simplex-chat terminal chat prototype> built with SimpleXMQ broker.
+
+homepage: https://github.com/simplex-chat/simplexmq#readme
 license: AGPL-3
-author: Evgeny Poberezkin
-maintainer: evgeny@poberezkin.com
-copyright: 2020 Evgeny Poberezkin
-category: Web, System, Services, Cryptography
+author: simplex.chat
+maintainer: chat@simplex.chat
+copyright: 2020-2022 simplex.chat
+category: Chat, Network, Web, System, Cryptography
 extra-source-files:
   - README.md
+  - CHANGELOG.md
 
 dependencies:
+  - aeson == 2.0.*
+  - ansi-terminal >= 0.10 && < 0.12
+  - asn1-encoding == 0.9.*
+  - asn1-types == 0.3.*
+  - async == 2.2.*
+  - attoparsec == 0.14.*
   - base >= 4.7 && < 5
   - base64-bytestring >= 1.0 && < 1.3
   - bytestring == 0.10.*
-  - containers
-  - cryptonite == 0.26.*
+  - case-insensitive == 1.2.*
+  - composition == 1.0.*
+  - constraints >= 0.12 && < 0.14
+  - containers == 0.6.*
+  - cryptonite >= 0.27 && < 0.30
+  - cryptostore == 0.2.*
+  - data-default == 0.7.*
+  - direct-sqlite == 2.3.*
+  - directory == 1.3.*
+  - filepath == 1.4.*
+  - http-types == 0.12.*
+  - http2 == 3.0.*
+  - generic-random >= 1.3 && < 1.5
+  - ini == 0.4.*
   - iso8601-time == 0.1.*
-  - mtl
-  - network == 3.1.*
-  - stm
+  - memory == 0.15.*
+  - mtl == 2.2.*
+  - network == 3.1.2.*
+  - network-transport == 0.5.*
+  - optparse-applicative >= 0.15 && < 0.17
+  - QuickCheck == 2.14.*
+  - process == 1.6.*
+  - random >= 1.1 && < 1.3
+  - simple-logger == 0.1.*
+  - sqlite-simple == 0.4.*
+  - stm == 2.5.*
+  - template-haskell == 2.16.*
+  - text == 1.2.*
   - time == 1.9.*
+  - time-manager == 0.0.*
+  - tls >= 1.5.7 && < 1.6
+  - transformers == 0.5.*
   - unliftio == 0.2.*
-  - unliftio-core == 0.1.*
+  - unliftio-core == 0.2.*
+  - websockets == 0.12.*
+  - x509 == 1.7.*
+  - x509-store == 1.6.*
+  - x509-validation == 1.6.*
+
+flags:
+  swift:
+    description: Enable swift JSON format
+    manual: True
+    default: False
+
+when:
+  - condition: flag(swift)
+    cpp-options:
+      - -DswiftJSON
 
 library:
   source-dirs: src
@@ -33,7 +89,23 @@ executables:
     source-dirs: apps/smp-server
     main: Main.hs
     dependencies:
-      - simplex-messaging
+      - simplexmq
+    ghc-options:
+      - -threaded
+
+  ntf-server:
+    source-dirs: apps/ntf-server
+    main: Main.hs
+    dependencies:
+      - simplexmq
+    ghc-options:
+      - -threaded
+
+  smp-agent:
+    source-dirs: apps/smp-agent
+    main: Main.hs
+    dependencies:
+      - simplexmq
     ghc-options:
       - -threaded
 
@@ -42,10 +114,12 @@ tests:
     source-dirs: tests
     main: Test.hs
     dependencies:
-      - simplex-messaging
+      - simplexmq
       - hspec == 2.7.*
       - hspec-core == 2.7.*
       - HUnit == 1.6.*
+      - QuickCheck == 2.14.*
+      - timeit == 2.0.*
 
 ghc-options:
   # - -haddock

protocol/agent-protocol.md

@@ -0,0 +1,419 @@
+# SMP agent protocol - duplex communication over SMP protocol
+
+## Table of contents
+
+- [Abstract](#abstract)
+- [SMP agent](#smp-agent)
+- [SMP servers management](#smp-servers-management)
+- [SMP agent protocol components](#smp-agent-protocol-components)
+- [Duplex connection procedure](#duplex-connection-procedure)
+- [Communication between SMP agents](#communication-between-smp-agents)
+  - [Message syntax](#messages-between-smp-agents)
+    - [HELLO message](#hello-message)
+    - [REPLY message](#reply-message)
+    - [MSG message](#msg-message)
+    - [INV message](#inv-message)
+    - [ACK message](#ack-message)
+    - [NEW message](#new-message)
+    - [DEL message](#del-message)
+- [SMP agent commands](#smp-agent-commands)
+  - [Client commands and server responses](#client-commands-and-server-responses)
+    - [NEW command and INV response](#new-command-and-inv-response)
+    - [JOIN command](#join-command)
+    - [CONF notification and LET command](#conf-notification-and-let-command)
+    - [REQ notification and ACPT command](#req-notification-and-acpt-command)
+    - [INFO and CON notifications](#info-and-con-notifications)
+    - [SUB command](#sub-command)
+    - [SEND command and MID, SENT and MERR responses](#send-command-and-mid-sent-and-merr-responses)
+    - [MSG notification](#msg-notification)
+    - [END notification](#end-notification)
+    - [OFF command](#off-command)
+    - [DEL command](#del-command)
+- [Connection request](#connection-request)
+
+## Abstract
+
+The purpose of SMP agent protocol is to define the syntax and the semantics of communications between the client and the agent that connects to [SMP](./simplex-messaging.md) servers.
+
+It provides:
+- protocol to create and manage bi-directional (duplex) connections between the users of SMP agents consisting of two (or more) separate unidirectional (simplex) SMP queues, abstracting away multiple steps required to establish bi-directional connections and any information about the servers location from the users of the agent protocol.
+- management of E2E encryption between SMP agents, generating ephemeral asymmetric keys for each connection.
+- SMP command authentication on SMP servers, generating ephemeral keys for each SMP queue.
+- TCP/TLS transport handshake with SMP servers.
+- validation of message integrity.
+
+SMP agent protocol provides no encryption or security on the client side - it is assumed that the agent is executed in the trusted and secure environment, in one of three ways:
+- via TCP network using secure connection.
+- via local port (when the agent runs on the same device as a separate process).
+- via agent library, when the agent logic is included directly into the client application - [SimpleX Chat for terminal](https://github.com/simplex-chat/simplex-chat) uses this approach.
+
+## SMP agent
+
+SMP agents communicate with each other via SMP servers using [simplex messaging protocol (SMP)](./simplex-messaging.md) according to the commands received from its users. This protocol is a middle layer in SimpleX protocols (above SMP protocol but below any application level protocol) - it is intended to be used by client-side applications that need secure asynchronous bi-directional communication channels ("connections").
+
+The agent must have a persistent storage to manage the states of known connections and of the client-side information of SMP queues that each connection consists of, and also the buffer of the most recent sent and received messages. The number of the messages that should be stored is implementation specific, depending on the error management approach that the agent implements; at the very least the agent must store the hashes and IDs of the last received and sent messages.
+
+## SMP servers management
+
+SMP agent protocol commands do not contain the addresses of the SMP servers that the agent will use to create and use the connections (excluding the server address in queue URIs used in JOIN command). The list of the servers is a part of the agent configuration and can be dynamically changed by the agent implementation:
+- by the client applications via any API that is outside of scope of this protocol.
+- by the agents themselves based on availability and latency of the configured servers.
+
+## SMP agent protocol components
+
+SMP agent protocol has 3 main parts:
+
+- the syntax and semantics of the messages that SMP agents exchange with each other in order to:
+  - negotiate establishing unidirectional (simplex) encrypted queues on SMP servers.
+  - exchange client messages and delivery notifications, providing sequential message IDs and message integrity (by including the hash of the previous message).
+- the syntax and semantics of the commands that are sent by the agent clients to the agents. This protocol allows to create and manage multiple connections, each consisting of two or more SMP queues.
+- the syntax and semantics of the message that the clients of SMP agents should send out-of-band (as pre-shared "invitation" including queue URIs) to protect [E2E encryption][1] from active attacks ([MITM attacks][2]).
+
+## Duplex connection procedure
+
+![Duplex connection procedure](./diagrams/duplex-messaging/duplex-creating.svg)
+
+The procedure of establishing a duplex connection is explained on the example of Alice and Bob creating a bi-directional connection consisting of two unidirectional (simplex) queues, using SMP agents (A and B) to facilitate it, and two different SMP servers (which could be the same server). It is shown on the diagram above and has these steps:
+
+1. Alice requests the new connection from the SMP agent A using SMP NEW command.
+2. Agent A creates an SMP connection on the server (using [SMP protocol](./simplex-messaging.md)) and responds to Alice with the invitation that contains queue information and the encryption key Bob's agent B should use. The invitation format is described in [Connection request](#connection-request).
+3. Alice sends the [connection request](#connection-request) to Bob via any secure channel (out-of-band message).
+4. Bob sends `JOIN` command with the connection request as a parameter to agent B to accept the connection.
+5. Establishing Alice's SMP queue (with SMP protocol commands):
+  - Agent B sends an "SMP confirmation" with SMP SEND command to the SMP queue specified in the connection request - SMP confirmation is an unauthenticated message with an ephemeral key that will be used to authenticate Bob's commands to the queue, as described in SMP protocol, and Bob's info (profile, public key for E2E encryption, etc.). This message is encrypted using key passed in the connection request (or with the derived key, in which case public key for key derivation should be sent in clear text).
+  - Agent A receives the SMP confirmation containing Bob's key and info as SMP MSG.
+  - Agent A notifies Alice sending REQ notification with Bob's info.
+  - Alice accepts connection request with ACPT command.
+  - Agent A secures the queue with SMP KEY command.
+  - Agent B tries sending authenticated SMP SEND command with agent `HELLO` message until it succeeds. Once it succeeds, Bob's agent "knows" the queue is secured.
+6. Agent B creates a new SMP queue on the server.
+7. Establish Bob's SMP queue:
+  - Agent B sends `REPLY` message (SMP SEND command) with the connection request to this 2nd queue to Alice's agent (via the 1st queue) - this connection request SHOULD use "simplex" URI scheme.
+  - Agent A, having received `REPLY` message, sends unauthenticated message (SMP SEND) to SMP queue with Alice agent's ephemeral key that will be used to authenticate Alice's commands to the queue, as described in SMP protocol, and Alice's info.
+  - Bob's agent receives the key and Alice's information and secures the queue (SMP KEY).
+  - Bob's agent sends the notification `INFO` with Alice's information to Bob.
+  - Alice's agent keeps sending `HELLO` message until it succeeds.
+8. Agents A and B notify Alice and Bob that connection is established.
+  - Once sending `HELLO` succeeds, Alice's agent sends to Alice `CON` notification that confirms that now both parties can communicate.
+  - Once Bob's agent receives `HELLO` from Alice's agent, it sends to Bob `CON` notification as well.
+
+At this point the duplex connection between Alice and Bob is established, they can use `SEND` command to send messages. The diagram also shows how the connection status changes for both parties, where the first part is the status of the SMP queue to receive messages, and the second part - the status of the queue to send messages.
+
+The most communication happens between the agents and servers, from the point of view of Alice and Bob there are 4 steps (not including notifications):
+
+1. Alice requests a new connection with `NEW` command and receives the invitation.
+2. Alice passes connection request out-of-band to Bob.
+3. Bob accepts the connection with `JOIN` command with the connection request to his agent.
+4. Alice accepts the connection with `ACPT` command.
+5. Both parties receive `CON` notification once duplex connection is established.
+
+Clients SHOULD support establishing duplex connection asynchronously (when parties are intermittently offline) by persisting intermediate states and resuming SMP queue subscriptions.
+
+## Communication between SMP agents
+
+To establish duplex connections and to send messages on behalf of their clients, SMP agents communicate via SMP servers.
+
+Agents use SMP message client body (the part of the SMP message after header - see [SMP protocol](./simplex-messaging.md)) to transmit agent client messages and exchange messages between each other.
+
+Each SMP message client body, once decrypted, contains 3 parts (one of them may include binary message body), as defined by `decryptedSmpMessageBody` syntax:
+
+- `agentMsgHeader` - agent message header that contains sequential agent message ID for a particular SMP queue, agent timestamp (ISO8601) and the hash of the previous message.
+- `agentMessage` - a command/message to the other SMP agent:
+  - to establish the connection with two SMP queues (`helloMsg`, `replyQueueMsg`)
+  - to send and to acknowledge user messages (`clientMsg`, `acknowledgeMsg`)
+  - to manage SMP queue rotation (`newQueueMessage`, `deleteQueueMsg`)
+  - to manage encryption key rotation (TODO)
+- `msgPadding` - an optional message padding to make all SMP messages have constant size, to prevent servers from observing the actual message size. The only case the message padding can be absent is when the message has exactly the maximum size, in all other cases the message MUST be padded to a fixed size.
+
+### Messages between SMP agents
+
+Message syntax below uses [ABNF][3] with [case-sensitive strings extension][4].
+
+```abnf
+decryptedSmpMessageBody = agentMsgHeader CRLF agentMessage CRLF msgPadding
+agentMsgHeader = agentMsgId SP previousMsgHash ; here `agentMsgId` is sequential ID set by the sending agent
+agentMsgId = 1*DIGIT
+previousMsgHash = encoded
+encoded = <base64 encoded>
+
+agentMessage = helloMsg / replyQueueMsg /
+               clientMsg / invitationMsg /
+               newQueueMessage / deleteQueueMsg 
+
+msgPadding = *OCTET ; optional random bytes to get messages to the same size (as defined in SMP message size)
+
+helloMsg = %s"H"
+
+replyQueueMsg = %s"R" connectionRequest ; `connectionRequest` is defined below
+; this message can only be sent by the second connection party
+
+clientMsg = %s"M" clientMsgBody
+clientMsgBody = *OCTET
+
+; TODO remove and move to "public" header
+invitationMsg = %s"INV" SP connReqInvitation SP connInfo
+; `connReqInvitation` and `connInfo` are defined below
+
+newQueueMsg = %s"N" queueURI
+; this message can be sent by any party to add SMP queue to the connection.
+; NOT SUPPORTED in the current implementation
+
+deleteQueueMsg = %s"D" queueURI
+; notification that the queue with passed URI will be deleted
+; no need to notify the other party about suspending queue separately, as suspended and deleted queues are indistinguishable to the sender
+; NOT SUPPORTED in the current implementation
+```
+
+#### HELLO message
+
+This is the first message that both agents send after the respective SMP queue is secured by the receiving agent (see diagram). It MAY contain the public key that the recipient would use to verify messages signed by the sender.
+
+Sending agent might need to retry sending HELLO message, as it would not have any other confirmation that the queue is secured other than the success of sending this message with the signed SMP SEND command.
+
+#### REPLY message
+
+This is the message that is sent by the agent that received an out-of-band connection request to pass the connection request for the reply SMP queues to the agent that originated the connection (see diagram).
+
+#### MSG message
+
+This is the agent envelope used to send client messages once the connection is established. Do not confuse it with the MSG response from SMP server to the agent and MSG response from SMP agent to the client that are sent in different contexts.
+
+#### INV message
+
+This message is sent to the SMP queue(s) in `connReqContact`, to establish a new connection via existing unsecured queue, that acts as a permanent connection link of a user.
+
+#### ACK message
+
+This message is sent to confirm the client message reception. It includes received message number, message hash and the reception status.
+
+#### NEW message
+
+This message is sent to add an additional SMP queue to the connection. Unlike REPLY message it can be sent at any time.
+
+#### DEL message 
+
+This message is sent to notify that the queue with passed URI will be deleted - having received this message, the receiving agent should no longer send messages to this queue. In case it was the last remaining send queue in the duplex connection, the agent MAY also delete the reply queue(s) in the connection.
+
+## SMP agent commands
+
+This part describes the transmissions between users and client-side SMP agents: commands that the users send to create and operate duplex connections and SMP agent responses and messages they deliver.
+
+Commands syntax below is provided using [ABNF][3] with [case-sensitive strings extension][4].
+
+Each transmission between the user and SMP agent must have this format/syntax:
+
+```abnf
+agentTransmission = [corrId] CRLF [connId] CRLF agentCommand
+
+corrId = 1*(%x21-7F) ; any characters other than control/whitespace
+
+connId = encoded
+
+agentCommand = (userCmd / agentMsg) CRLF
+userCmd = newCmd / joinCmd / letCmd / acceptCmd / subscribeCmd / sendCmd / acknowledgeCmd / suspendCmd / deleteCmd
+agentMsg = invitation / confMsg / connReqMsg / connInfo / connected / unsubscribed / connDown / connUp / messageId / sent / messageError / message / received / ok / error
+
+newCmd = %s"NEW" SP connectionMode [SP %s"NO_ACK"] ; response is `invitation` or `error`
+; NO_ACK parameter currently not supported
+
+connectionMode = %s"INV" / %s"CON"
+
+invitation = %s"INV" SP connectionRequest ; `connectionRequest` is defined below
+
+confMsg = %s"CONF" SP confirmationId SP msgBody
+; msgBody here is any binary information identifying connection request
+
+letCmd = %s"LET" SP confirmationId SP msgBody
+; msgBody here is any binary information identifying connecting party
+
+confirmationId = 1*DIGIT
+
+connReqMsg = %s"REQ" SP invitationId SP msgBody
+; msgBody here is any binary information identifying connection request
+
+acceptCmd = %s"ACPT" SP invitationId SP msgBody
+; msgBody here is any binary information identifying connecting party
+
+invitationId = 1*DIGIT
+
+connInfo = %s"INFO" SP msgBody
+; msgBody here is any binary information identifying connecting party
+
+connected = %s"CON"
+
+subscribeCmd = %s"SUB" ; response is `ok` or `error`
+
+unsubscribed = %s"END"
+; when another agent (or another client of the same agent)
+; subscribes to the same SMP queue on the server
+
+connDown = %s"DOWN"
+; lost connection (e.g. because of Internet connectivity or server is down)
+
+connUp = %s"UP"
+; restored connection
+
+joinCmd = %s"JOIN" SP connectionRequest SP connInfo [SP %s"NO_REPLY"] [SP %s"NO_ACK"]
+; `connectionRequest` and `connInfo` are defined below
+; response is `connected` or `error`
+; parameters NO_REPLY and NO_ACK are currently not supported
+
+suspendCmd = %s"OFF" ; can be sent by either party, response `ok` or `error`
+
+deleteCmd = %s"DEL" ; can be sent by either party, response `ok` or `error`
+
+sendCmd = %s"SEND" SP msgBody
+; send syntax is similar to that of SMP protocol, but it is wrapped in SMP message
+msgBody = stringMsg | binaryMsg
+stringMsg = ":" string ; until CRLF in the transmission
+string = *(%x01-09 / %x0B-0C / %x0E-FF %) ; any characters other than NUL, CR and LF
+binaryMsg = size CRLF msgBody CRLF ; the last CRLF is in addition to CRLF in the transmission
+size = 1*DIGIT ; size in bytes
+msgBody = *OCTET ; any content of specified size - safe for binary
+
+messageId = %s"MID" SP agentMsgId
+
+sent = %s"SENT" SP agentMsgId
+
+messageError = %s"MERR" SP agentMsgId SP <errorType>
+
+message = %s"MSG" SP msgIntegrity SP recipientMeta SP brokerMeta SP senderMeta SP binaryMsg
+recipientMeta = %s"R=" agentMsgId "," agentTimestamp ; receiving agent message metadata 
+brokerMeta = %s"B=" brokerMsgId "," brokerTimestamp ; broker (server) message metadata
+senderMeta = %s"S=" agentMsgId ; sending agent message ID 
+brokerMsgId = encoded
+brokerTimestamp = <date-time>
+msgIntegrity = ok / msgIntegrityError
+
+msgIntegrityError = %s"ERR" SP msgIntegrityErrorType
+msgIntegrityErrorType = skippedMsgErr / badMsgIdErr / badHashErr
+
+skippedMsgErr = %s"NO_ID" SP missingFromMsgId SP missingToMsgId
+badMsgIdErr = %s"ID" SP previousMsgId ; ID is lower than the previous
+badHashErr = %s"HASH"
+
+missingFromMsgId = agentMsgId
+missingToMsgId = agentMsgId
+previousMsgId = agentMsgId
+
+acknowledgeCmd = %s"ACK" SP agentMsgId ; ID assigned by receiving agent (in MSG "R")
+
+received = %s"RCVD" SP agentMsgId SP msgIntegrity
+; ID assigned by sending agent (in SENT response)
+; currently not implemented
+
+msgStatus = ok | error
+
+ok = %s"OK"
+
+error = %s"ERR" SP <errorType>
+```
+
+### Client commands and server responses
+
+#### NEW command and INV response
+
+`NEW` command is used to create a connection and a connection request to be sent out-of-band to another protocol user (the joining party). It should be used by the client of the agent that initiates creating a duplex connection (the initiating party).
+
+`INV` response is sent by the agent to the client of the initiating party.
+
+`NEW` command has `connectionMode` parameter to define the connection mode - to be used to communicate with a single contact (invitation mode, `connectionMode` is `INV`) or to accept connection requests from anybody (contact mode, `connectionMode` is `CON`). The type of connection request is determined by `connectionMode` parameter.
+
+#### JOIN command
+
+It is used to create a connection and accept the connection request received out-of-band. It should be used by the client of the agent that accepts the connection (the joining party).
+
+#### CONF notification and LET command
+
+When the joining party uses `JOIN` command to accept connection invitation created with `NEW INV` command, the initiating party will receive `CONF` notification with some numeric identifier and an additional binary information, that can be used to identify the joining party or for any other purpose.
+
+To continue with the connection the initiating party should use `LET` command.
+
+#### REQ notification and ACPT command
+
+When the joining party uses `JOIN` command to connect to the contact created with `NEW CON` command, the initiating party will receive `REQ` notification with some numeric identifier and an additional binary information, that can be used to identify the joining party or for any other purpose.
+
+To continue with the connection the party that created the contact should use `ACPT` command.
+
+#### INFO and CON notifications
+
+After the initiating party proceeds with the connection using `ACPT` command, the joining party will receive `INFO` notification that can be used to identify the initiating party or for any other purpose.
+
+Once the connection is established and ready to accept client messages, both agents will send `CON` notification to their clients.
+
+#### SUB command
+
+This command can be used by the client to resume receiving messages from the connection that was created in another TCP/client session. Agent response to this command can be `OK` or `ERR` in case connection does not exist (or can only be used to send connections - e.g. when the reply queue was not created).
+
+#### SEND command and MID, SENT, RCVD and MERR responses
+
+`SEND` command is used by the client to send messages.
+
+`MID` response with the message ID (the sequential message number that includes both sent and received messages in the connection) is sent to the client to confirm that the message is accepted by the agent, before it is sent to the SMP server.
+
+`SENT` notification is sent by the agent to confirm that the message was delivered to at least one of SMP servers. This notification contains the same message ID as `MID` notification. `SENT` notification, depending on network availability, can be sent at any time later, potentially in the next client session.
+
+`RCVD` notification is sent by the agent when it receives `ACK` message from the receiving agent. This notification contains reception status, only one successful notification will be sent, and multiple error notifications will be sent in case `ACK` had error status.
+
+In case of the failure to send the message for any other reason than network connection or message queue quota - e.g. authentication error (`ERR AUTH`) or syntax error (`ERR CMD error`), the agent will send to the client `MERR` notification with the message ID, and this message delivery will no longer be attempted to this SMP queue.
+
+#### MSG notification
+
+It is sent by the agent to the client when agent receives the message from the SMP server. It has message ID and timestamp from both the receiving and sending agents and from SMP server:
+- recipient agent ID is intended to be used to refer to the message in the future.
+- sender agent ID is intended to be used to identify any missed / skipped message(s)
+- broker ID should be used to detect duplicate deliveries (it would happen if TCP connection is lost before the message is acknowledged by the agent - see [SMP protocol](./simplex-messaging.md))
+
+#### END notification
+
+It is sent by the agent to the client when agent receives SMP protocol `END` notification from SMP server. It indicates that another agent has subscribed to the same SMP queue on the server and the server terminated the subscription of the current agent.
+
+#### DOWN and UP notifications
+
+These notifications are sent when server or network connection is, respectively, `DOWN` or back `UP`.
+
+All the subscriptions made in the current client session will be automatically resumed when `UP` notification is received.
+
+#### OFF command
+
+It is used to suspend the receiving SMP queue - sender will no longer be able to send the messages to the connection, but the recipient can retrieve the remaining messages. Agent response to this command can be `OK` or `ERR`. This command is irreversible.
+
+#### DEL command
+
+It is used to delete the connection and all messages in it, as well as the receiving SMP queue and all messages in it that were remaining on the server. Agent response to this command can be `OK` or `ERR`. This command is irreversible.
+
+## Connection request
+
+Connection request `connectionRequest` is generated by SMP agent in response to `newCmd` command (`"NEW"`), used by another party user with `joinCmd` command (`"JOIN"`), and then another connection request is sent by the agent in `replyQueueMsg` and used by the first party agent to connect to the reply queue (the second part of the process is invisible to the users).
+
+Connection request syntax:
+
+```
+connectionRequest = connectionScheme "/" connReqType "#/?smp=" smpQueues "&e2e=" e2eEncryption
+connReqType = %s"invitation" / %s"contact"
+; this parameter has the same meaning as connectionMode in agent commands
+; `NEW INV` creates `invitation` connection request, `NEW CON` - `contact`
+connectionScheme = (%s"https://" clientAppServer) | %s"simplex:"
+clientAppServer = hostname [ ":" port ]
+; client app server, e.g. simplex.chat
+e2eEncryption = encryptionScheme ":" publicKey
+encryptionScheme = %s"rsa" ; end-to-end encryption and key exchange protocols,
+                           ; the current hybrid encryption scheme (RSA-OAEP/AES-256-GCM-SHA256)
+                           ; will be replaced with double ratchet protocol and DH key exchange.
+publicKey = <base64url X509 SPKI key encoding>
+smpQueues = smpQueue [ "," 1*smpQueue ] ; SMP queues for the connection
+smpQueue = <URL-encoded queueURI defined in SMP protocol>
+```
+
+All parameters are passed via URI hash to avoid sending them to the server (in case "https" scheme is used) - they can be used by the client-side code and processed by the client application. Parameters `smp` and `e2e` can be present in any order, any unknown additional parameters SHOULD be ignored.
+
+`clientAppServer` is not an SMP server - it is a server that shows the instruction on how to download the client app that will connect using this connection request. This server can also host a mobile or desktop app manifest so that this link is opened directly in the app if it is installed on the device.
+
+"simplex" URI scheme in `connectionProtocol` can be used instead of client app server, to connect without creating any web traffic. Client apps MUST support this URI scheme.
+
+See SMP protocol [out-of-band messages](./simplex-messaging.md#out-of-band-messages) for syntax of `queueURI`.
+
+[1]: https://en.wikipedia.org/wiki/End-to-end_encryption
+[2]: https://en.wikipedia.org/wiki/Man-in-the-middle_attack
+[3]: https://tools.ietf.org/html/rfc5234
+[4]: https://tools.ietf.org/html/rfc7405

protocol/diagrams/duplex-messaging/duplex-creating.mmd

@@ -0,0 +1,79 @@
+sequenceDiagram
+  participant A as Alice
+  participant AA as Alice's<br>agent
+  participant AS as Alice's<br>server
+  participant BS as Bob's<br>server
+  participant BA as Bob's<br>agent
+  participant B as Bob
+
+  note over AA, BA: status (receive/send): NONE/NONE
+
+  note over A, AA: 1. request connection from agent
+  A ->> AA: NEW: create<br>duplex connection
+ 
+  note over AA, AS: 2. create Alice's SMP queue
+  AA ->> AS: NEW: create SMP queue
+  AS ->> AA: IDS: SMP queue IDs
+  note over AA: status: NEW/NONE
+
+  AA ->> A: INV: invitation<br>to connect
+  note over AA: status: PENDING/NONE
+
+  note over A, B: 3. out-of-band invitation
+  A ->> B: OOB: invitation to connect
+
+  note over BA, B: 4. accept connection
+  B ->> BA: JOIN:<br>via invitation info
+  note over BA: status: NONE/NEW
+
+  note over BA, AA: 5. establish Alice's SMP queue
+  BA ->> AS: SEND: Bob's info and sender server key (SMP confirmation)
+  note over BA: status: NONE/CONFIRMED
+  activate BA
+  AS ->> AA: MSG: Bob's info and<br>sender server key
+  note over AA: status: CONFIRMED/NONE
+  AA ->> AS: ACK: confirm message
+  AA ->> A: REQ: connection request ID<br>and Bob's info
+  A ->> AA: ACPT: accept connection request,<br>send Alice's info
+  AA ->> AS: KEY: secure queue
+  note over AA: status: SECURED/NONE
+
+  BA ->> AS: SEND: HELLO: try sending until successful
+  deactivate BA
+  note over BA: status: NONE/ACTIVE
+  AS ->> AA: MSG: HELLO: Alice's agent<br>knows Bob can send
+  note over AA: status: ACTIVE/NONE
+  AA ->> AS: ACK: confirm message
+
+  note over BA, BS: 6. create Bob's SMP queue
+  BA ->> BS: NEW: create SMP queue
+  BS ->> BA: IDS: SMP queue IDs
+  note over BA: status: NEW/ACTIVE
+
+  note over AA, BA: 7. establish Bob's SMP queue
+  BA ->> AS: SEND: REPLY: invitation to the connect
+  note over BA: status: PENDING/ACTIVE
+  AS ->> AA: MSG: REPLY: invitation<br>to connect
+  note over AA: status: ACTIVE/NEW
+  AA ->> AS: ACK: confirm message
+
+  AA ->> BS: SEND: Alice's info and sender's server key
+  note over AA: status: ACTIVE/CONFIRMED
+  activate AA
+  BS ->> BA: MSG: Alice's info and<br>sender's server key
+  note over BA: status: CONFIRMED/ACTIVE
+  BA ->> B: INFO: Alice's info
+  BA ->> BS: ACK: confirm message
+  BA ->> BS: KEY: secure queue
+  note over BA: status: SECURED/ACTIVE
+
+  AA ->> BS: SEND: HELLO: try sending until successful
+  deactivate AA
+  note over AA: status: ACTIVE/ACTIVE
+  BS ->> BA: MSG: HELLO: Bob's agent<br>knows Alice can send
+  note over BA: status: ACTIVE/ACTIVE
+  BA ->> BS: ACK: confirm message
+
+  note over A, B: 8. notify users about connection success
+  AA ->> A: CON: connected
+  BA ->> B: CON: connected

protocol/diagrams/notifications/register-token.mmd

@@ -0,0 +1,30 @@
+sequenceDiagram
+  participant M as mobile app
+  participant C as chat core
+  participant A as agent
+  participant P as push server
+  participant APN as APN
+
+  note over M, APN: get device token
+  M ->> APN: registerForRemoteNotifications()
+  APN ->> M: device token
+
+  note over M, P: register device token with push server
+  M ->> C: /_ntf register <token>
+  C ->> A: registerNtfToken(<token>)
+  A ->> P: TNEW
+  P ->> A: ID (tokenId)
+  A ->> C: registered
+  C ->> M: registered
+
+  note over M, APN: verify device token
+  P ->> APN: E2E encrypted code<br>in background<br>notification
+  APN ->> M: deliver background notification with e2ee verification token
+  M ->> C: /_ntf verify <e2ee code>
+  C ->> A: verifyNtfToken(<e2ee code>)
+  A ->> P: TVFY code
+  P ->> A: OK / ERR
+  A ->> C: verified
+  C ->> M: verified
+
+  note over M, APN: now token ID can be used

protocol/diagrams/notifications/subscription.mmd

@@ -0,0 +1,40 @@
+sequenceDiagram
+  participant M as mobile app
+  participant C as chat core
+  participant A as agent
+  participant S as SMP server
+  participant N as NTF server
+  participant APN as APN
+
+  note over M, APN: register subscription
+
+  alt register existing
+    M -->> A: on /_ntf register, for subscribed queues
+  else create new connection
+    A -->> S: NEW / JOIN
+    note over A, S: ...<br>Connection handshake<br>...
+    S -->> A: CON
+  end
+  A ->> S: NKEY nKey
+  S ->> A: NID nId
+  A ->> N: SNEW tknId dhKey (smpServer, nId, nKey)
+  N ->> A: ID subId dhKey
+  N ->> S: NSUB nId
+  S ->> N: OK [/ NMSG]
+
+  note over M, APN: notify about message
+
+  S ->> N: NMSG
+  N ->> APN: APNSMutableContent<br>ntfQueue, nonce
+  APN ->> M: UNMutableNotificationContent
+  note over M, S: ...<br>Client awaken, message is received<br>...
+  S ->> M: message
+  note over M: mutate notification
+
+  note over M, APN: change APN token
+
+  APN ->> M: new device token
+  M -->> C: /_ntf_sub update tkn
+  C -->> A: updateNtfToken()
+  A -->> N: TUPD tknId newDeviceToken
+  note over M, N: ...<br>Verify token<br>...

protocol/diagrams/simplex-messaging/simplex-creating.mmd

@@ -0,0 +1,20 @@
+sequenceDiagram
+  participant B as Bob (sender)
+  participant S as server (queue RID)
+  participant A as Alice (recipient)
+
+  note over A: creating queue<br>("public" key RK<br>for msg retrieval)
+  A ->> S: 1. create queue ("NEW")
+  S ->> A: respond with queue RID and SID ("IDS")
+
+  note over A: out-of-band msg<br>(sender's queue SID<br>and "public" key EK<br>to encrypt msgs)
+  A -->> B: 2. send out-of-band message
+
+  note over B: confirm queue<br>("public" key SK for<br>sending messages<br>and any optional<br>info encrypted with<br>"public" key EK)
+  B ->> S: 3. confirm queue ("SEND" command not signed)
+
+  S ->> A: 4. deliver Bob's message
+  note over A: decrypt message<br>("private" key EK)
+  A ->> S: 5. secure queue ("KEY", RK-signed)
+
+  note over S: 6. simplex<br>queue RID<br>is ready to use!

protocol/diagrams/simplex-messaging/simplex-op.mmd

@@ -0,0 +1,26 @@
+sequenceDiagram
+  participant S as sender (client)
+  participant A as transport
+  participant Q as pubsub
+  participant P as transport
+  participant R as receiver (client)
+  note over R: sign subscription (1)
+  R ->> P: subscribe to messages
+  note over P: verify subscriber (1)
+  alt subscriber verified?
+    P -->> Q: subscribe
+  else
+    P ->> R: reject subscription
+  end
+  note over S: sign message (2)
+  S ->> A: send message
+  note over A: verify sender (2)
+  alt sender verified?
+    A -->> Q: queue message
+    activate Q
+  else
+    A ->> S: reject message
+  end
+  Q -->> P: take message
+  deactivate Q
+  P ->> R: deliver message

protocol/diagrams/simplex-messaging/simplex-using.mmd

@@ -0,0 +1,10 @@
+sequenceDiagram
+  participant B as Bob (sender)
+  participant S as server (queue RID)
+  participant A as Alice (recipient)
+
+  note over B: encrypt message<br>("public" key EK)
+  B ->> S: 1. send message to SID (SK-signed command)
+
+  S ->> A: 2. receive messages from RID (RK-signed subscription)
+  note over A: decrypt message<br>("private" key EK)

protocol/diagrams/simplex-messaging/simplex.mmd

@@ -0,0 +1,11 @@
+graph LR
+  VS{{"verify sender (SK)"}}
+  VR{{"verify recipient (RK)"}}
+
+  S(sender) -->|msg| VS
+  subgraph "server (queue RID, SID)"
+    VS --> DB[("storage")]
+    DB --> VR
+  end
+  R(recipient) -->|"1) sub"| VR
+  VR -->|"2) msg"| R

protocol/overview-tjr.md

@@ -0,0 +1,313 @@
+Revision 1, 2022-01-01
+
+Evgeny Poberezkin
+
+# SimpleX: messaging and application platform
+
+## Table of contents
+
+- [Introduction](#introduction)
+  - [What is SimpleX](#what-is-simplex)
+  - [SimpleX objectives](#simplex-objectives)
+  - [In Comparison](#in-comparison)
+- [Technical Details](#technical-details)
+  - [Trust in Servers](#trust-in-servers)
+  - [Client -> Server Communication](#client---server-communication)
+  - [SimpleX Messaging Protocol](#simplex-messaging-protocol)
+  - [SimpleX Agents](#simplex-agents)
+  - [Encryption Primitives Used](#encryption-primitives-used)
+- [Threat model](#threat-model)
+- [Acknowledgements](#acknowledgements)
+
+## Introduction
+
+#### What is SimpleX
+
+SimpleX as a whole is a platform upon which applications can be built. [SimpleX Chat](https://github.com/simplex-chat/simplex-chat) is one such application that also serves as an example and reference application.
+
+ - [SimpleX Messaging Protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md) (SMP) is a protocol to send messages in one direction to a recipient, relying on a server in-between. The messages are delivered via uni-directional queues created by recipients.
+
+ - SMP runs over a transport protocol (shown below as TLS) that provides integrity, server authentication, confidentiality, and transport channel binding.
+
+ - A SimpleX Server is one of those servers.
+
+ - The SimpleX Network is the term used for the collective of SimpleX Servers that facilitate SMP.
+
+ - SimpleX Client libraries speak SMP to SimpleX Servers and provide a low-level API not generally intended to be used by applications.
+
+ - SimpleX Agents interface with SimpleX Clients to provide a more high-level API intended to be used by applications. Typically they are embedded as libraries, but are designed so they can also be abstracted into local services.
+
+
+*Diagram showing the SimpleX Chat app, with logical layers of the chat application interfacing with a SimpleX Agent library, which in turn interfaces with a SimpleX Client library. The Client library in turn speaks the Messaging Protocol to a SimpleX Server.*
+
+```
+  User's Computer                 Internet                    Third-Party Server
+------------------     |   ----------------------     |   -------------------------
+                       |                              |
+   SimpleX Chat        |                              |
+                       |                              |
++----------------+     |                              |
+|    Chat App    |     |                              |
++----------------+     |                              |
+|  SimpleX Agent |     |                              |
++----------------+    -------------- TLS ----------------    +----------------+
+| SimpleX Client | ------ SimpleX Messaging Protocol ------> | SimpleX Server |
++----------------+    -----------------------------------    +----------------+
+                       |                              |
+```
+
+#### SimpleX objectives
+
+1. Provide messaging infrastructure for distributed applications. This infrastructure needs to have the following qualities:
+
+   - Security against passive and active (man-in-the-middle) attacks: the parties should have reliable end-to-end encryption and be able to detect the presence of an active attacker who modified, deleted or added messages.
+
+   - Privacy: protect against traffic correlation attacks to determine the contacts that the users communicate with.
+
+   - Reliability: the messages should be delivered even if some participating network servers or receiving clients fail, with “at least once” delivery guarantee.
+
+   - Integrity: the messages sent in one direction are ordered in a way that sender and recipient agree on; the recipient can detect when a message was removed or changed.
+
+   - Asynchronous delivery: it should not be required that both communicating parties (client devices, services or applications) are online for reliable message delivery.
+
+   - Low latency: the delay introduced by the network should not be higher than 100ms-1s in addition to the underlying TCP network latency.
+
+2. Provide better communication security and privacy than the alternative instant messaging solutions.  In particular SimpleX provides better privacy of metadata (who talks to whom and when) and better security against active network attackers and malicious servers.
+
+3. Balance user experience with privacy requirements, prioritizing experience of mobile device users.
+
+#### In Comparison
+
+SimpleX network has a design similar to P2P networks, but unlike most P2P networks it consists of clients and servers without depending on any centralized component.
+In comparison to more traditional messaging applications (e.g. WhatsApp, Signal, Telegram) the key differences of SimpleX network are:
+
+- participants do not need to have globally unique addresses to communicate, instead they use redundant unidirectional (simplex) messaging queues, with a separate set of queues for each contact.
+
+- connection requests are passed out-of-band, non-optionally protecting key exchange against man-in-the-middle attack.
+
+- simple message queues provided by network servers are used by the clients to create more complex communication scenarios, such as duplex one-to-one communication, transmitting files, group communication without central servers, and content/communication channels.
+
+- servers do not store any user information (no user profiles or contacts, or messages once they are delivered), and primarily use in-memory persistence.
+
+- users can change servers with minimal disruption - even after an in-use server disappears, simply by changing the configuration on which servers the new queues are created.
+
+## Technical Details
+
+#### Trust in Servers
+
+Clients communicate directly with servers (but not with other clients) using SimpleX Messaging Protocol (SMP) running over some transport protocol that provides integrity, server authentication, confidentiality, and transport channel binding. By default, we assume this transport protocol is TLS.
+
+Users use multiple servers, and choose where to receive their messages. Accordingly, they send messages to their communication partners' chosen servers.
+
+Although end-to-end encryption is always present, users place a degree of trust in servers. This trust decision is very similar to a user's choice of email provider; however the trust placed in a SimpleX server is significantly less. Notably, there is no re-used identifier or credential between queues on the same (or different) servers. While a user *may* re-use a connection to fetch from multiple queues, or connect to a server from the same IP address, both are choices a user may opt into to break the promise of un-correlatable queues.
+
+Users may trust a server because:
+
+- They deploy and control the servers themselves from the available open-source code. This has the trade-offs of strong trust in the server but limited metadata obfuscation to a passive network observer. Techniques such as noise traffic, traffic mixing (incurring latency), and using an onion routing transport protocol can mitigate that latter.
+
+- They use servers from a trusted commercial provider. The more clients the provider has, the less metadata about the communication times is leaked to the network observers.
+
+- Users trust their contacts and the servers they chose.
+
+By default, servers do not retain access logs, and permanently delete messages and queues when requested.  Messages persist only in memory until they cross a threshold of time, typically on the order of days.[0] There is still a risk that a server maliciously records all queues and messages (even though encrypted) sent via the same transport connection to gain a partial knowledge of the user’s communications graph and other meta-data.
+
+SimpleX supports measures (managed transparently to the user at the agent level) to mitigate the trust placed in servers.  These include rotating the queues in use between users, noise traffic, and supporting overlay networks such as Tor.
+
+[0] While configurable by servers, a minimum value is enforced by the default software. SimpleX Agents provide redundant routing over queues to mitigate against message loss.
+
+
+#### Client -> Server Communication
+
+Utilizing TLS grants the SimpleX Messaging Protocol (SMP) server authentication and metadata protection to a passive network observer. But SMP does not rely on the transport protocol for message confidentiality or client authentication. The SMP protocol itself provides end-to-end confidentiality, authentication, and integrity of messages between communicating parties.
+
+Servers have long-lived, self-signed, offline certificates whose hash is pre-shared with clients over secure channels - either provided with the client library or provided in the secure introduction between clients.  The offline certificate signs an online certificate used in the transport protocol handshake. [0]
+
+If the transport protocol's confidentiality is broken, incoming and outgoing messages to the server cannot be correlated by message contents. Additionally, because of encryption at the SMP layer, impersonating the server is not sufficient to pass (and therefore correlate) a message from a sender to recipient - the only attack possible is to drop the messages. Only by additionally *compromising* the server can one pass and correlate messages.
+
+It's important to note that the SMP protocol does not do server authentication. Instead we rely upon the fact that an attacker who tricks the transport protocol into authenticating the server incorrectly cannot do anything with the SMP messages except drop them.
+
+After the connection is established, the client sends blocks of a fixed size 16Kb, and the server replies with the blocks of the same size to reduce metadata observable to a network adversary. The protocol has been designed to make traffic correlation attacks difficult, adapting ideas from Tor, remailers, and more general onion and mix networks. It does not try to replace Tor though - SimpleX servers can be deployed as onion services and SimpleX clients can communicate with servers over Tor to further improve participants privacy.
+
+By using fixed-size blocks, oversized for the expected content, the vast majority of traffic is uniform in nature. When enough traffic is transiting a server simultaneously, the server acts as a (very) low-latency mix node.  We can't rely on this behavior to make a security claim, but we have engineered to take advantage of it when we can. As mentioned, this holds true even if the transport connection is compromised.
+
+The protocol does not protect against attacks targeted at particular users with known identities - e.g., if the attacker wants to prove that two known users are communicating, they can achieve it. At the same time, it substantially complicates large-scale traffic correlation, making determining the real user identities much less effective.
+
+[0] Future versions of SMP may add support for revocation lists of certificates, presently this risk is mitigated by the SMP protocol itself.
+
+
+#### SimpleX Messaging Protocol
+
+SMP is initialized with an in-person or out-of-band introduction message, where Alice provides Bob with details of a server (including IP, port, and hash of the long-lived offline certificate), a queue ID, and Alice's public key for her receiving queue. These introductions are similar to the PANDA key-exchange, in that if observed, the adversary can race to establish the communication channel instead of the intended participant. [0]
+
+Because queues are uni-directional, Bob provides an identically-formatted introduction message to Alice over Alice's now-established receiving queue.
+
+When setting up a queue, the server will create separate sender and recipient queue IDs (provided to Alice during set-up and Bob during initial connection). Additionally, during set-up Alice will perform a DH exchange with the server to agree upon a shared secret. This secret will be used to re-encrypt Bob's incoming message before Alice receives it, creating the anti-correlation property earlier-described should the transport encryption be compromised.
+
+[0] Users can additionally create public 'contact queues' that are only used to receive connection requests.  
+
+#### SimpleX Agents
+
+SimpleX agents provide higher-level operations compared to SimpleX Clients, who are primarily concerned with creating queues and communicating with servers using SMP.  Agent operations include:
+
+- Managing sets of bi-directional, redundant queues for communication partners
+
+- Providing end-to-end encryption of messages
+
+- Rotating queues periodically with communication partners
+
+- Noise traffic
+
+#### Encryption Primitives Used
+
+- Ed448 to sign/verify commands to SMP servers (Ed25519 is also supported via client/server configuration).
+- Curve25519 for DH exchange to agree:
+  - the shared secret between server and recipient (to encrypt message bodies - it avoids shared cipher-text in sender and recipient traffic)
+  - the shared secret between sender and recipient (to encrypt messages end-to-end in each queue - it avoids shared cipher-text in redundant queues).
+- [NaCl crypto_box](https://nacl.cr.yp.to/box.html) encryption scheme (curve25519xsalsa20poly1305) for message body encryption between server and recipient and for E2E per-queue encryption.
+- SHA256 to validate server offline certificates.
+- [double ratchet](https://signal.org/docs/specifications/doubleratchet/) protocol for end-to-end message encryption between the agents:
+  - Curve448 keys to agree shared secrets required for double ratchet initialization (using [X3DH](https://signal.org/docs/specifications/x3dh/) key agreement with 2 ephemeral keys for each side),
+  - AES-GCM AEAD cipher,
+  - SHA512-based HKDF for key derivation.
+
+## Threat Model
+
+#### Global Assumptions
+
+ - A user protects their local database and key material
+ - The user's application is authentic, and no local malware is running
+ - The cryptographic primitives in use are not broken
+ - A user's choice of servers is not directly tied to their identity or otherwise represents distinguishing information about the user.
+
+#### A passive adversary able to monitor the traffic of one user
+
+*can:*
+
+ - identify that and when a user is using SimpleX
+
+ - block SimpleX traffic
+
+ - determine which servers the user communicates with
+
+ - observe how much traffic is being sent, and make guesses as to its purpose.
+
+*cannot:*
+
+ - see who sends messages to the user and who the user sends the messages to
+
+#### A passive adversary able to monitor a set of senders and recipients
+
+ *can:*
+
+ - identify who and when is using SimpleX
+
+ - learn which SimpleX Messaging Protocol servers are used as receive queues for which users
+
+ - learn when messages are sent and received
+
+ - perform traffic correlation attacks against senders and recipients and correlate senders and recipients within the monitored set, frustrated by the number of users on the servers
+
+ - observe how much traffic is being sent, and make guesses as to its purpose
+
+*cannot, even in case of a compromised transport protocol:*
+
+ - perform traffic correlation attacks with any increase in efficiency over a non-compromised transport protocol
+
+#### SimpleX Messaging Protocol server
+
+*can:*
+
+- learn when a queue recipient or sender is online
+
+- know how many messages are sent via the queue (although some may be noise)
+
+- perform queue correlation (matching multiple queues to a single user) via either a re-used transport connection, user's IP Address, or connection timing regularities
+
+- learn a user's IP address, track them through other IP addresses they use to access the same queue, and infer information (e.g. employer) based on the IP addresses, as long as Tor is not used.
+
+- drop all future messages inserted into a queue, detectable only over other, redundant queues
+
+- lie about the state of a queue to the recipient and/or to the sender  (e.g. suspended or deleted when it is not).
+
+- spam a user with invalid messages
+
+*cannot:*
+
+- undetectably add, duplicate, or corrupt individual messages
+
+- undetectably drop individual messages, so long as a subsequent message is delivered
+
+- learn the contents of messages
+
+- distinguish noise messages from regular messages except via timing regularities
+
+- compromise the user's end-to-end encryption with an active attack
+
+#### An attacker who obtained Alice's (decrypted) chat database
+
+*can:*
+
+- see the history of all messages exchanged by Alice with her communication partners
+
+- see shared profiles of contacts and groups
+
+- surreptitiously receive new messages sent to Alice via existing queues; until communication queues are rotated or the Double-Ratchet advances forward
+
+- prevent Alice from receiving all new messages sent to her - either surreptitiously by emptying the queues regularly or overtly by deleting them
+
+- send messages from the user to their contacts; recipients will detect it as soon as the user sends the next message, because the previous message hash won’t match (and potentially won’t be able to decrypt them in case they don’t keep the previous ratchet keys).
+
+*cannot:*
+
+- impersonate a sender and send messages to the user whose database was stolen. Doing so requires also compromising the server (to place the message in the queue, that is possible until the Double-Ratchet advances forward) or the user's device at a subsequent time (to place the message in the database).
+
+- undetectably communicate at the same time as Alice with her contacts. Doing so would result in the contact getting different messages with repeated IDs.
+
+- undetectably monitor message queues in realtime without alerting the user they are doing so, as a second subscription request unsubscribes the first and notifies the second.
+
+#### A user’s contact
+
+*can:*
+
+- spam the user with messages
+
+- forever retain messages from the user
+
+*cannot:*
+
+- cryptographically prove to a third-party that a message came from a user (assuming the user’s device is not seized)
+
+- prove that two contacts they have is the same user
+
+- cannot collaborate with another of the user's contacts to confirm they are communicating with the same user
+
+#### An attacker who observes Alice showing an introduction message to Bob
+
+*can:*
+
+ - Impersonate Bob to Alice
+
+*cannot:*
+
+ - Impersonate Alice to Bob
+
+#### An attacker with Internet access
+
+*can:*
+
+- Denial of Service SimpleX messaging servers
+
+- spam a user's public “contact queue” with connection requests
+
+*cannot:*
+
+- send messages to a user who they are not connected with
+
+- enumerate queues on a SimpleX server
+
+
+## Acknowledgements
+
+Efim Poberezkin contributed to the design and implementation of [SimpleX Messaging Protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md) and [SimpleX Agent Protocol](https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md) since 2019.
+
+Adam Langley's [Pond](https://github.com/agl/pond) inspired some of the recent improvements and the structure of this document.

protocol/simplex-messaging.md

@@ -0,0 +1,855 @@
+# Simplex Messaging Protocol (SMP)
+
+## Table of contents
+
+- [Abstract](#abstract)
+- [Introduction](#introduction)
+- [SMP Model](#smp-model)
+- [Out-of-band messages](#out-of-band-messages)
+- [Simplex queue](#simplex-queue)
+- [SMP queue URI](#smp-queue-uri)
+- [SMP procedure](#smp-procedure)
+- [SMP qualities and features](#smp-qualities-and-features)
+- [Cryptographic algorithms](#cryptographic-algorithms)
+- [Simplex queue IDs](#simplex-queue-ids)
+- [Server security requirements](#server-security-requirements)
+- [Message delivery notifications](#message-delivery-notifications)
+- [SMP Transmission structure](#smp-transmission-structure)
+- [SMP commands](#smp-commands)
+  - [Correlating responses with commands](#correlating-responses-with-commands)
+  - [Command authentication](#command-authentication)
+  - [Keep-alive command](#keep-alive-command)
+  - [Recipient commands](#recipient-commands)
+    - [Create queue command](#create-queue-command)
+    - [Subscribe to queue](#subscribe-to-queue)
+    - [Secure queue command](#secure-queue-command)
+    - [Enable notifications command](#enable-notifications-command)
+    - [Acknowledge message delivery](#acknowledge-message-delivery)
+    - [Suspend queue](#suspend-queue)
+    - [Delete queue](#delete-queue)
+  - [Sender commands](#sender-commands)
+    - [Send message](#send-message)
+  - [Notifier commands](#notifier-commands)
+    - [Subscribe to queue notifications](#subscribe-to-queue-notifications)
+  - [Server messages](#server-messages)
+    - [Queue IDs response](#queue-ids-response)
+    - [Deliver queue message](#deliver-queue-message)
+    - [Notifier queue ID response](#notifier-queue-id-response)
+    - [Deliver message notification](#deliver-message-notification)
+    - [Subscription END notification](#subscription-end-notification)
+    - [Error responses](#error-responses)
+    - [OK response](#ok-response)
+- [Appendices](#appendices)
+  - [Appendix A. Transport connection with the SMP server](#appendix-a)
+
+## Abstract
+
+Simplex Messaging Protocol is a transport agnostic client-server protocol for asynchronous distributed secure unidirectional message transmission via persistent simplex message queues.
+
+It's designed with the focus on communication security and integrity, under the assumption that any part of the message transmission network can be compromised.
+
+It is designed as a low level protocol for other application protocols to solve the problem of secure and private message transmission, making [MITM attack][1] very difficult at any part of the message transmission system.
+
+## Introduction
+
+The objective of Simplex Messaging Protocol (SMP) is to facilitate the secure and private unidirectional transfer of messages from senders to recipients via persistent simplex queues managed by the message broker (server).
+
+SMP is independent of any particular transmission system and requires only a reliable ordered data stream channel. While this document describes transport over TCP, other transports are also possible.
+
+The protocol describes the set of commands that recipients and senders can exchange with SMP servers to create and to operate unidirectional "queues" (a data abstraction identifying one of many communication channels managed by the server) and to send messages from the sender to the recipient via the SMP server.
+
+More complex communication scenarios can be designed using multiple queues - for example, a duplex communication channel can be made of 2 simplex queues.
+
+The protocol is designed with the focus on privacy and security, to some extent deprioritizing reliability by requiring that SMP servers only store messages until they are acknowledged by the recipients and, in any case, for a limited period of time. For communication scenarios requiring more reliable transmission the users should use several SMP servers to pass each message and implement some additional protocol to ensure that messages are not removed, inserted or changed - this is out of scope of this document.
+
+SMP does not use any form of participants' identities and provides [E2EE][2] without the possibility of [MITM attack][1] relying on two pre-requisites:
+
+- the users can establish a secure encrypted transport connection with the SMP server. [Appendix A](#appendix-a) describes SMP transport protocol of such connection over TCP, but any other transport connection protocol can be used.
+
+- the recipient can pass a single message to the sender via a pre-existing secure and private communication channel (out-of-band message) - the information in this message is used to encrypt messages and to establish connection with SMP server.
+
+## SMP Model
+
+The SMP model has three communication participants: the recipient, the message broker (SMP server) that is chosen and, possibly, controlled by the recipient, and the sender.
+
+SMP server manages multiple "simplex queues" - data records on the server that identify communication channels from the senders to the recipients. The same communicating party that is the sender in one queue, can be the recipient in another - without exposing this fact to the server.
+
+The queue record consists of 2 unique random IDs generated by the server, one for the recipient and another for the sender, and 2 keys to authenticate the recipient and the sender respectively, provided by the client. The users of SMP protocol must use a unique key for each queue, to avoid the possibility of aggregating and analyzing their queues in case SMP server is compromised.
+
+Creating and using the queue requires sending commands to the SMP server from the recipient and the sender - they are described in detail in [SMP commands](#smp-commands) section.
+
+## Out-of-band messages
+
+The out-of-band message with the queue information is sent via some trusted alternative channel from the recipient to the sender. This message is used to share one or several [queue URIs](#smp-queue-uri) that parties can use to establish the initial connection, the encryption scheme and, it can include the public key(s) for end-to-end encryption.
+
+The approach to out-of-band message passing and their syntax should be defined in application-level protocols.
+
+## Simplex queue
+
+The simplex queue is the main unit of SMP protocol. It is used by:
+
+- Sender of the queue (who received out-of-band message) to send messages to the server using sender's queue ID, signed by sender's key.
+
+- Recipient of the queue (who created the queue and sent out-of-band message) will use it to retrieve messages from the server, signing the commands by the recipient key. Recipient decrypts the messages with the key negotiated during the creation of the queue.
+
+- Participant identities are not shared with the server - new unique keys and queue IDs are used for each queue.
+
+This simplex queue can serve as a building block for more complex communication network. For example, two (or more, for redundancy) simplex queues can be used to create a duplex communication channel. Higher level primitives that are only known to system participants in their client applications can be created as well - e.g., contacts, conversations, groups and broadcasts. Simplex messaging servers only have the information about the low-level simplex queues. In this way a high level of privacy and security of the communication is provided. Application level primitives are not in scope of this protocol.
+
+This approach is based on the concept of [unidirectional networks][4] that are used for applications with high level of information security.
+
+Access to each queue is controlled with unique (not shared with other queues) asymmetric key pairs, separate for the sender and the recipient. The sender and the receiver have private keys, and the server has associated public keys to authenticate participants' commands by verifying cryptographic signatures.
+
+The messages sent over the queue are end-to-end encrypted using the DH secret agreed via out-of-band message and SMP confirmation.
+
+**Simplex queue diagram:**
+
+![Simplex queue](./diagrams/simplex-messaging/simplex.svg)
+
+Queue is defined by recipient ID `RID` and sender ID `SID`, unique for the server. Sender key (`SK`) is used by the server to verify sender's commands (identified by `SID`) to send messages. Recipient key (`RK`) is used by the server to verify recipient's commands (identified by `RID`) to retrieve messages.
+
+The protocol uses different IDs for sender and recipient in order to provide an additional privacy by preventing the correlation of senders and recipients commands sent over the network - in case the encrypted transport is compromised, it would still be difficult to correlate senders and recipients without access to the queue records on the server.
+
+## SMP queue URI
+
+The SMP queue URIs MUST include server identity, queue hostname, an optional port, sender queue ID and the public key that the clients must use to verify responses. Server identity is used to establish secure connection protected from MITM attack with SMP server (see [Appendix A](#appendix-a) for SMP transport protocol).
+
+The [ABNF][8] syntax of the queue URI is:
+
+```abnf
+queueURI = %s"smp://" smpServer "/" queueId "#" recipientDhPublicKey
+smpServer = serverIdentity "@" srvHost [":" port]
+srvHost = <hostname> ; RFC1123, RFC5891
+port = 1*DIGIT
+serverIdentity = base64url
+queueId = base64url
+base64url = <base64url encoded binary> ; RFC4648, section 5
+recipientDhPublicKey = x509UrlEncoded
+; the recipient's Curve25519 key for DH exchange to derive the secret
+; that the sender will use to encrypt delivered messages
+; using [NaCl crypto_box][16] encryption scheme (curve25519xsalsa20poly1305).
+
+x509UrlEncoded = <base64url X509 key encoding>
+```
+
+`hostname` can be IP address or domain name, as defined in RFC 1123, section 2.1.
+
+`port` is optional, the default TCP port for SMP protocol is 5223.
+
+`serverIdentity` is a required hash of the server certificate SPKI block (without line breaks, header and footer) used by the client to validate server certificate during transport handshake (see [Appendix A](#appendix-a))
+
+## SMP procedure
+
+The SMP procedure of creating a simplex queue on SMP server is explained using participants Alice (the recipient) who wants to receive messages from Bob (the sender).
+
+To create and start using a simplex queue Alice and Bob follow these steps:
+
+1. Alice creates a simplex queue on the server:
+
+    1. Decides which SMP server to use (can be the same or different server that Alice uses for other queues) and opens secure encrypted transport connection to the chosen SMP server (see [Appendix A](#appendix-a)).
+
+    2. Generates a new random public/private key pair (encryption key - `EK`) that she did not use before for Bob to encrypt the messages.
+
+    3. Generates another new random public/private key pair (recipient key - `RK`) that she did not use before for her to sign commands and to decrypt the transmissions received from the server.
+
+    4. Generates one more random key pair (recipient DH key - `RDHK`) to negotiate symmetric key that will be used by the server to encrypt message bodies delivered to Alice (to avoid shared cipher-text inside transport connection).
+
+    5. Sends `"NEW"` command to the server to create a simplex queue (see `create` in [Create queue command](#create-queue-command)). This command contains previously generated unique "public" keys `RK` and `RDHK`. `RK` will be used to verify the following commands related to the same queue signed by its private counterpart, for example to subscribe to the messages received to this queue or to update the queue, e.g. by setting the key required to send the messages (initially Alice creates the queue that accepts unsigned messages, so anybody could send the message via this queue if they knew the queue sender's ID and server address).
+
+    6. The server sends `"IDS"` response with queue IDs (`queueIds`):
+
+        - Recipient ID `RID` for Alice to manage the queue and to receive the messages.
+
+        - Sender ID `SID` for Bob to send messages to the queue.
+
+        - Server public DH key (`SDHK`) to negotiate a shared secret for message body encryption, that Alice uses to derive a shared secret with the server `SS`.
+
+2. Alice sends an out-of-band message to Bob via the alternative channel that both Alice and Bob trust (see [protocol abstract](#simplex-messaging-protocol-abstract)). The message must include:
+
+    - Unique "public" key (`EK`) that Bob must use for E2E key agreement.
+
+    - SMP server hostname and information to open secure encrypted transport connection (see [Appendix A](#appendix-a)).
+
+    - Sender queue ID `SID` for Bob to use.
+
+3. Bob, having received the out-of-band message from Alice, connects to the queue:
+
+    1. Generates a new random public/private key pair (sender key - `SK`) that he did not use before for him to sign messages sent to Alice's server.
+
+    2. Prepares the confirmation message for Alice to secure the queue. This message includes:
+
+        - Previously generated "public" key `SK` that will be used by Alice's server to authenticate Bob's messages, once the queue is secured.
+
+        - Optionally, any additional information (application specific, e.g. Bob's profile name and details).
+
+    3. Encrypts the confirmation body with the "public" key `EK` (that Alice provided via the out-of-band message).
+
+    4. Sends the encrypted message to the server with queue ID `SID` (see `send` in [Send message](#send-message)). This initial message to the queue must not be signed - signed messages will be rejected until Alice secures the queue (below).
+
+4. Alice receives Bob's message from the server using recipient queue ID `RID` (possibly, via the same transport connection she already has opened - see `message` in [Deliver queue message](#deliver-queue-message)):
+
+    1. She decrypts received message body using the secret `SS`.
+
+    2. She decrypts received message with [key agreed with sender using] "private" key `EK`.
+
+    3. Even though anybody could have sent the message to the queue with ID `SID` before it is secured (e.g. if communication is compromised), Alice would ignore all messages until the decryption succeeds (i.e. the result contains the expected message format). Optionally, in the client application, she also may identify Bob using the information provided, but it is out of scope of SMP protocol.
+
+5. Alice secures the queue `RID` with `"KEY"` command so only Bob can send messages to it (see [Secure queue command](#secure-queue-command)):
+
+    1. She sends the `KEY` command with `RID` signed with "private" key `RK` to update the queue to only accept requests signed by "private" key `SK` provided by Bob. This command contains unique "public" key `SK` previously generated by Bob.
+
+    2. From this moment the server will accept only signed commands to `SID`, so only Bob will be able to send messages to the queue `SID` (corresponding to `RID` that Alice has).
+
+    3. Once queue is secured, Alice deletes `SID` and `SK` - even if Alice's client is compromised in the future, the attacker would not be able to send messages pretending to be Bob.
+
+6. The simplex queue `RID` is now ready to be used.
+
+This flow is shown on the sequence diagram below.
+
+**Creating simplex queue from Bob to Alice:**
+
+![Creating queue](./diagrams/simplex-messaging/simplex-creating.svg)
+
+Bob now can securely send messages to Alice:
+
+1. Bob sends the message:
+
+    1. He encrypts the message to Alice with "public" key `EK` (provided by Alice, only known to Bob, used only for one simplex queue).
+
+    2. He signs `"SEND"` command to the server queue `SID` using the "private" key `SK` (that only he knows, used only for this queue).
+
+    3. He sends the command to the server (see `send` in [Send message](#send-message)), that the server will authenticate using the "public" key `SK` (that Alice earlier received from Bob and provided to the server via `"KEY"` command).
+
+2. Alice receives the message(s):
+
+    1. She signs `"SUB"` command to the server to subscribe to the queue `RID` with the "private" key `RK` (see `subscribe` in [Subscribe to queue](#subscribe-to-queue)).
+
+    2. The server, having authenticated Alice's command with the "public" key `RK` that she provided, delivers Bob's message(s) (see `message` in [Deliver queue message](#deliver-queue-message)).
+
+    3. She decrypts Bob's message(s) with the "private" key `EK` (that only she has).
+
+    4. She acknowledges the message reception to the server with `"ACK"` so that the server can delete the message and deliver the next messages.
+
+This flow is show on sequence diagram below.
+
+**Sending messages from Bob to Alice via simplex queue:**
+
+![Using queue](./diagrams/simplex-messaging/simplex-using.svg)
+
+**Simplex queue operation:**
+
+![Simplex queue operations](./diagrams/simplex-messaging/simplex-op.svg)
+
+Sequence diagram does not show E2E encryption - server knows nothing about encryption between the sender and the receiver.
+
+A higher level protocol application protocol should define the semantics that allow to use two simplex queues (or two sets of queues for redundancy) for the bi-directional or any other communication scenarios.
+
+The SMP is intentionally unidirectional - it provides no answer to how Bob will know that the transmission succeeded, and whether Alice received any messages. There may be a scenario when Alice wants to securely receive the messages from Bob, but she does not want Bob to have any proof that she received any messages - this low-level protocol can be used in this scenario, as all Bob knows as a fact is that he was able to send one unsigned message to the server that Alice provided, and now he can only send messages signed with the key `SK` that he sent to the server - it does not prove that any message was received by Alice.
+
+For practical purposes of bi-directional conversation, now that Bob can securely send encrypted messages to Alice, Bob can create the second simplex queue that will allow Alice to send messages to Bob in the same way, sending the second queue details via the first queue. If both Alice and Bob have their respective unique "public" keys (Alice's and Bob's `EK`s of two separate queues), or pass additional keys to sign the messages, the conversation can be both encrypted and signed.
+
+The established queues can also be used to change the encryption keys providing [forward secrecy][5], or to negotiate using other SMP queue(s).
+
+This protocol also can be used for off-the-record messaging, as Alice and Bob can use multiple queues between them and only information they pass to each other allows proving their identity, so if they want to share anything off-the-record they can initiate a new queue without linking it to any other information they exchanged. As a result, this protocol provides better anonymity and better protection from [MITM][1] than [OTR][6] protocol.
+
+## SMP qualities and features
+
+Simplex Messaging Protocol:
+
+- Defines only message-passing protocol:
+
+  - Transport agnostic - the protocol does not define how clients connect to the servers. It can be implemented over any ordered data stream channel: TCP connection, HTTP with long polling, websockets, etc.
+
+  - Not semantic - the protocol does not assign any meaning to queues and messages. While on the application level the queues and messages can have different meaning (e.g., for messages: text or image chat message, message acknowledgement, participant profile information, status updates, changing "public" key to encrypt messages, changing servers, etc.), on SMP protocol level all the messages are binary and their meaning can only be interpreted by client applications and not by the servers - this interpretation is out of scope of this protocol.
+
+- Client-server architecture:
+
+  - Multiple servers, that can be deployed by the system users, can be used to send and retrieve messages.
+
+  - Servers do not communicate with each other and do not "know" about other servers.
+
+  - Clients only communicate with servers (excluding the initial out-of-band message), so the message passing is asynchronous.
+
+  - For each queue, the message recipient defines the server through which the sender should send messages.
+
+  - While multiple servers and multiple queues can be used to pass each message, it is in scope of application level protocol(s), and out of scope of this protocol.
+
+  - Servers store messages only until they are retrieved by the recipients, and in any case, for a limited time.
+
+  - Servers are required to NOT store any message history or delivery log, but even if the server is compromised, it does not allow to decrypt the messages or to determine the list of queues established by any participant - this information is only stored on client devices.
+
+- The only element provided by SMP servers is simplex queues:
+
+  - Each queue is created and managed by the queue recipient.
+
+  - Asymmetric encryption is used to sign and verify the requests to send and receive the messages.
+
+  - One unique "public" key is used by the servers to authenticate requests to send the messages into the queue, and another unique "public" key - to retrieve the messages from the queue. "Unique" here means that each "public" key is used only for one queue and is not used for any other context - effectively, this key is not public and does not represent any participant identity.
+
+  - Both recipient and sender "public" keys are provided to the server by the queue recipient. "Public" key `RK` is provided when the queue is created, public key `SK` is provided when the queue is secured.
+
+  - The "public" keys known to the server and used to authenticate commands from the participants are unrelated to the keys used to encrypt and decrypt the messages - the latter keys are also unique per each queue but they are only known to participants, not to the servers.
+
+  - Messaging graph can be asymmetric: Bob's ability to send messages to Alice does not automatically lead to the Alice's ability to send messages to Bob.
+
+## Cryptographic algorithms
+
+Simplex messaging clients and servers must cryptographically sign commands, responses and messages for the following operations:
+
+- With the recipient's key `RK` (server to verify):
+  - create the queue (`NEW`)
+  - subscribe to queue (`SUB`)
+  - secure the queue (`KEY`)
+  - enable queue notifications (`NKEY`)
+  - acknowledge received messages (`ACK`)
+  - suspend the queue (`OFF`)
+  - delete the queue (`DEL`)
+- With the sender's key `SK` (server to verify):
+  - send messages (`SEND`)
+- With the optional notifier's key:
+  - subscribe to message notifications (`NSUB`)
+- With the server's key (for recipient and sender to verify)
+  - queue IDs response (`IDS`)
+  - notifier queue ID response (`NID`)
+  - delivered messages (`MSG`)
+  - `OK` and `ERR` responses (excluding error responses not related to a queue)
+
+To sign/verify transmissions clients and servers MUST use Ed25519 or Ed448 algorithm defined in [RFC8709][15].
+
+To encrypt/decrypt message bodies delivered to the recipients, servers/clients MUST use x25519 or x448 algorithm defined in [RFC8709][15] to derive the shared secret (TODO encryption scheme).
+
+Clients MUST encrypt message bodies sent via SMP servers - the protocol for this end-to-end encryption should be chosen by the clients using SMP protocol.
+
+The reasons to use these algorithms:
+
+- Faster operation than RSA algorithms.
+- DH key exchange provides forward secrecy.
+
+Future versions of the protocol may allow different cryptographic algorithms.
+
+## Simplex queue IDs
+
+Simplex messaging servers MUST generate 2 different IDs for each new queue - for the recipient (that created the queue) and for the sender. It is REQUIRED that:
+
+- These IDs are different and unique within the server.
+- Based on random bytes generated with cryptographically strong pseudo-random number generator.
+
+## Server security requirements
+
+Simplex messaging server implementations MUST NOT create, store or send to any other servers:
+
+- Logs of the client commands and transport connections in the production environment.
+
+- History of deleted queues, retrieved or acknowledged messages (deleted queues MAY be stored temporarily as part of the queue persistence implementation).
+
+- Snapshots of the database they use to store queues and messages (instead simplex messaging clients must manage redundancy by using more than one simplex messaging server). In-memory persistence is recommended.
+
+- Any other information that may compromise privacy or [forward secrecy][4] of communication between clients using simplex messaging servers.
+
+## Message delivery notifications
+
+Supporting message delivery while the client mobile app is not running requires sending push notifications with the device token. All alternative mechanisms for background message delivery are unreliable, particularly on iOS platform. Obviously, supporting push notification delivery by simply subscribing to messages would reduce meta-data privacy as it allows to see all queues that a given device uses.
+
+To protect the privacy of the recipients, there are several commands in SMP protocol that allow enabling and subscribing to message notifications from SMP queues, using separate set of "notifier keys" and via separate queue IDs - as long as SMP server is not compromised, these notifier queue IDs cannot be correlated with recipient or sender queue IDs.
+
+The clients can optionally instruct a dedicated push notification server to subscribe to notifications and deliver push notifications to the device, which can then retrieve the messages in the background and send local notifications to the user - this is out of scope of SMP protocol. The commands that SMP protocol provides to allow it:
+
+- `enableNotifications` (`"NKEY"`) with `notifierId` (`"NID"`) response - see [Enable notifications command](#enable-notifications-command).
+- `subscribeNotifications` (`"NSUB"`) - see [Subscribe to queue notifications](#subscribe-to-queue-notifications).
+- `messageNotification` (`"NMSG"`) - see [Deliver message notification](#deliver-message-notification).
+
+## SMP Transmission structure
+
+Each transport block (SMP transmission) has a fixed size of 16384 bytes for traffic uniformity.
+
+Some parts of SMP transmission are padded to a fixed size; this padding is uniformly added as a word16 encoded in network byte order - see `paddedString` syntax.
+
+In places where some part of the transmission should be padded, the syntax for `paddedNotation` is used:
+
+```
+paddedString = originalLength string pad
+originalLength = 2*2 OCTET
+pad = N*N"#" ; where N = paddedLength - originalLength - 2
+
+paddedNotation = <padded(string, paddedLength)>
+; string - un-padded string
+; paddedLength - required length after padding, including 2 bytes for originalLength
+```
+
+Each transmission between the client and the server must have this format/syntax:
+
+```
+paddedTransmission = <padded(transmission), 16384>
+transmission = [signature] SP signed
+signed = sessionIdentifier SP [corrId] SP [queueId] SP smpCommand
+; corrId is required in client commands and server responses,
+; it is empty in server notifications.
+corrId = 1*32(%x21-7F) ; any characters other than control/whitespace
+queueId = encoded ; max 32 bytes when decoded (24 bytes is used),
+; empty queue ID is used with "create" command and in some server responses
+signature = encoded
+; empty signature can be used with "send" before the queue is secured with secure command
+; signature is always empty with "ping" and "serverMsg"
+encoded = <base64 encoded binary>
+```
+
+`base64` encoding should be used with padding, as defined in section 4 of [RFC 4648][9]
+
+## SMP commands
+
+Commands syntax below is provided using [ABNF][8] with [case-sensitive strings extension][8a].
+
+```abnf
+smpCommand = ping / recipientCmd / send / subscribeNotifications / serverMsg
+recipientCmd = create / subscribe / secure / enableNotifications /
+               acknowledge / suspend / delete
+serverMsg = queueIds / message / notifierId / messageNotification /
+            unsubscribed / ok / error
+```
+
+The syntax of specific commands and responses is defined below.
+
+### Correlating responses with commands
+
+The server should send `queueIds`, `error` and `ok` responses in the same order within each queue ID as the commands received in the transport connection, so that they can be correlated by the clients. To simplify correlation of commands and responses, the server must use the same `corrId` in the response as in the command sent by the client.
+
+If the transport connection is closed before some responses are sent, these responses should be discarded.
+
+### Command authentication
+
+SMP servers must authenticate all transmissions (excluding `ping` and initial `send` commands) by verifying the client signatures. Command signature should be generated by applying the algorithm specified for the queue to the `signed` block of the transmission, using the key associated with the queue ID (recipient's, sender's or notifier's, depending on which queue ID is used).
+
+### Keep-alive command
+
+To keep the transport connection alive and to generate noise traffic the clients should use `ping` command to which the server responds with `ok` response. This command should be sent unsigned and without queue ID.
+
+```abnf
+ping = %s"PING"
+```
+
+This command is always send unsigned.
+
+### Recipient commands
+
+Sending any of the commands in this section (other than `create`, that is sent without queue ID) is only allowed with recipient's ID (`RID`). If sender's ID is used the server must respond with `"ERR AUTH"` response (see [Error responses](#error-responses)).
+
+#### Create queue command
+
+This command is sent by the recipient to the SMP server to create a new queue. The syntax is:
+
+```abnf
+create = %s"NEW " recipientSignaturePublicKey recipientDhPublicKey
+recipientSignaturePublicKey = length x509encoded
+; the recipient's Ed25519 or Ed448 public key to verify commands for this queue
+
+recipientDhPublicKey = length x509encoded
+; the recipient's Curve25519 key for DH exchange to derive the secret
+; that the server will use to encrypt delivered message bodies
+; using [NaCl crypto_box][16] encryption scheme (curve25519xsalsa20poly1305).
+
+x509encoded = <binary X509 key encoding>
+
+length = 1*1 OCTET
+```
+
+If the queue is created successfully, the server must send `queueIds` response with the recipient's and sender's queue IDs and public keys to sign all responses and messages and to encrypt delivered message bodies:
+
+```abnf
+queueIds = %s"IDS " recipientId senderId srvDhPublicKey
+serverDhPublicKey = length x509encoded
+; the server's Curve25519 key for DH exchange to derive the secret
+; that the server will use to encrypt delivered message bodies to the recipient
+recipientId = length *OCTET ; 16-24 bytes
+senderId = length *OCTET ; 16-24 bytes
+```
+
+Once the queue is created, the recipient gets automatically subscribed to receive the messages from that queue, until the transport connection is closed. The `subscribe` command is needed only to start receiving the messages from the existing queue when the new transport connection is opened.
+
+`NEW` transmission MUST be signed using the private part of the `recipientSignaturePublicKey` – this verifies that the client has the private key that will be used to sign subsequent commands for this queue.
+
+`IDS` response transmission MUST be sent with empty queue ID (the third part of the transmission).
+
+#### Subscribe to queue
+
+When the simplex queue was not created in the current transport connection, the recipient must use this command to start receiving messages from it:
+
+```abnf
+subscribe = %s"SUB"
+```
+
+If subscription is successful the server must respond with the first available message or with `ok` response if no messages are available. The recipient will continue receiving the messages from this queue until the transport connection is closed or until another transport connection subscribes to the same simplex queue - in this case the first subscription should be cancelled and [subscription END notification](#subscription-end-notification) delivered.
+
+The first message will be delivered either immediately or as soon as it is available; to receive the following message the recipient must acknowledge the reception of the message (see [Acknowledge message delivery](#acknowledge-message-delivery)).
+
+This transmission and its response MUST be signed.
+
+#### Secure queue command
+
+This command is sent by the recipient to the server to add sender's key to the queue:
+
+```abnf
+secure = %s"KEY " senderSignaturePublicKey
+senderSignaturePublicKey = length x509encoded
+; the sender's Ed25519 or Ed448 key to verify SEND commands for this queue
+```
+
+`senderKey` is received from the sender as part of the first message - see [Send Message](#send-message) command.
+
+Once the queue is secured only signed messages can be sent to it.
+
+#### Enable notifications command
+
+This command is sent by the recipient to the server to add notifier's key to the queue, to allow push notifications server to receive notifications when the message arrives, via a separate queue ID, without receiving message content.
+
+```abnf
+enableNotifications = %s"NKEY " notifierKey
+notifierKey = length x509encoded
+; the notifier's Ed25519 or Ed448 public key public key to verify NSUB command for this queue
+```
+
+The server will respond with `notifierId` response if notifications were enabled and the notifier's key was successfully added to the queue:
+
+```abnf
+notifierId = %s"NID " notifierId
+notifierId = length *OCTET ; 16-24 bytes
+```
+
+This response is sent with the recipient's queue ID (the third part of the transmission).
+
+To receive the message notifications, `subscribeNotifications` command ("NSUB") must be sent signed with the notifier's key.
+
+#### Acknowledge message delivery
+
+The recipient should send the acknowledgement of message delivery once the message was stored in the client, to notify the server that the message should be deleted:
+
+```abnf
+acknowledge = %s"ACK"
+```
+
+Even if acknowledgement is not sent by the recipient, the server should limit the time of message storage, whether it was delivered to the recipient or not.
+
+Having received the acknowledgement, SMP server should immediately delete the message and then send the next available message or respond with `ok` if there are no more messages available in this simplex queue.
+
+#### Suspend queue
+
+The recipient can suspend a queue prior to deleting it to make sure that no messages are lost:
+
+```abnf
+suspend = %s"OFF"
+```
+
+The server must respond with `"ERR AUTH"` to any messages sent after the queue was suspended (see [Error responses](#error-responses)).
+
+The server must respond `ok` to this command if it was successful.
+
+This command can be sent multiple times (in case transport connection was interrupted and the response was not delivered), the server should still respond `ok` even if the queue is already suspended.
+
+There is no command to resume the queue. Servers must delete suspended queues that were not deleted after some period of time.
+
+#### Delete queue
+
+The recipient can delete the queue, whether it was suspended or not.
+
+All undelivered messages must be deleted as soon as this command is received, before the response is sent.
+
+```abnf
+delete = %s"DEL"
+```
+
+### Sender commands
+
+Currently SMP defines only one command that can be used by senders - `send` message. This command must be used with sender's ID, if recipient's ID is used the server must respond with `"ERR AUTH"` response (see [Error responses](#error-responses)).
+
+#### Send message
+
+This command is sent to the server by the sender both to confirm the queue after the sender received out-of-band message from the recipient and to send messages after the queue is secured:
+
+```abnf
+send = %s"SEND " smpEncMessage
+smpEncMessage = smpPubHeader sentMsgBody ; message up to 16088 bytes
+smpPubHeader = smpClientVersion ("1" senderPublicDhKey / "0")
+smpClientVersion = word16
+senderPublicDhKey = length x509encoded
+; sender's Curve25519 public key to agree DH secret for E2E encryption in this queue
+; it is only sent in confirmation message
+x509encoded = <binary X509 key encoding>
+sentMsgBody = 16032*16032 OCTET
+; E2E-encrypted smpClientMessage padded to 16032 bytes before encryption
+word16 = 2*2 OCTET
+```
+
+The first message is sent to confirm the queue - it should contain sender's server key (see decrypted message syntax below) - this first message must be sent without signature.
+
+Once the queue is secured (see [Secure queue command](#secure-queue-command)), the following send commands must be sent with the signature.
+
+The server must respond with `"ERR AUTH"` response in the following cases:
+
+- the queue does not exist or is suspended
+- the queue is secured but the transmission does NOT have a signature
+- the queue is NOT secured but the transmission has a signature
+
+Until the queue is secured, the server should accept any number of unsigned messages - it both enables the legitimate sender to resend the confirmation in case of failure and also allows the simplex messaging client to ignore any confirmation messages that may be sent by the attackers (assuming they could have intercepted the queue ID in the server response, but do not have a correct encryption key passed to sender in out-of-band message).
+
+The body should be encrypted with the recipient's "public" key (`EK`); once decrypted it must have this format:
+
+```abnf
+sentMsgBody = <encrypted padded(smpClientMessage, 16032)>
+smpClientMessage = smpPrivHeader clientMsgBody
+smpPrivHeader = emptyHeader / smpConfirmationHeader
+emptyHeader = " "
+smpConfirmationHeader = %s"K" senderKey
+senderKey = length x509encoded
+; the sender's Ed25519 or Ed448 public key to sign SEND commands for this queue
+clientMsgBody = *OCTET ; up to 16016 in case of emptyHeader
+```
+
+`clientHeader` in the initial unsigned message is used to transmit sender's server key and can be used in the future revisions of SMP protocol for other purposes.
+
+SMP transmission structure for sent messages:
+
+```
+------- transmission (= 16384 bytes)
+    2 | originalLength
+ 276- | signature sessionId corrId queueId %s"SEND" SP (1+114 + 1+32? + 1+32 + 1+24 + 4+1 = 210)
+      ....... smpEncMessage (= 16088 bytes = 16384 - 296 bytes)
+         8- | smpPubHeader (for messages it is only version and '0' to mean "no DH key" = 3 bytes)
+         24 | nonce for smpClientMessage
+         16 | auth tag for smpClientMessage
+            ------- smpClientMessage (E2E encrypted, = 16032 bytes = 16088 - 48)
+                2 | originalLength
+               12- | smpPrivHeader
+                  .......
+                        | clientMsgBody (<= 16016 bytes = 16032 - 14)
+                  .......
+               0+ | smpClientMessage pad
+            ------- smpClientMessage end
+            |
+      ....... smpEncMessage end
+  18+ | transmission pad
+------- transmission end
+```
+
+SMP transmission structure for received messages:
+
+```
+------- transmission (= 16384 bytes)
+    2 | originalLength
+ 276- | signature sessionId corrId queueId %s"MSG" SP msgId timestamp (1+114 + 1+32? + 1+32 + 1+24 + 3+1 + 24+1 + 8 = 243)
+   16 | auth tag (msgId is used as nonce)
+      ------- serverEncryptedMsg (= 16090 bytes = 16384 - 294 bytes)
+          2 | originalLength
+            ....... smpEncMessage (= 16088 bytes = 16090 - 2 bytes)
+               16- | smpPubHeader (empty header for the message)
+               24 | nonce for smpClientMessage
+               16 | auth tag for smpClientMessage
+                  ------- smpClientMessage (E2E encrypted, = 16032 bytes = 16088 - 56 bytes)
+                      2 | originalLength
+                     16- | smpPrivHeader (empty header for the message)
+                        ....... clientMsgBody (<= 16016 bytes = 16032 - 16)
+                              -- TODO move internal structure (below) to agent protocol
+                          20- | agentPublicHeader (the size is for user messages post handshake, without E2E X3DH keys - it is version and 'M' for the messages - 3 bytes in total)
+                              ....... E2E double-ratchet encrypted (<= 15996 bytes = 16016 - 20)
+                                  1 | encoded double ratchet header length (it is 123 now)
+                                123 | encoded double ratchet header, including:
+                                         2 | version
+                                        16 | double-ratchet header iv
+                                        16 | double-ratchet header auth tag
+                                      1+88 | double-ratchet header (actual size is 69 bytes, the rest is reserved)
+                                 16 | message auth tag (IV generated from chain ratchet)
+                                    ------- encrypted agent message (= 15856 bytes = 15996 - 140)
+                                        2 | originalLength
+                                      64- | agentHeader (the actual size is 41 = 8 + 1+32)
+                                        2 | %s"MM"
+                                          .......
+                                                | application message (<= 15788 bytes = 15856 - 68)
+                                          .......
+                                       0+ | encrypted agent message pad
+                                    ------- encrypted agent message end
+                                    |
+                              ....... E2E double-ratchet encrypted end
+                              |
+                              -- TODO move internal structure (above) to agent protocol
+                        ....... clientMsgBody end
+                     0+ | smpClientMessage pad
+                  ------- smpClientMessage end
+                  |
+            ....... smpEncMessage end
+         0+ | serverEncryptedMsg pad
+      ------- serverEncryptedMsg end
+   0+ | transmission pad
+------- transmission end
+```
+
+### Notifier commands
+
+#### Subscribe to queue notifications
+
+The push notifications server (notifier) must use this command to start receiving message notifications from the queue:
+
+```abnf
+subscribeNotifications = %s"NSUB"
+```
+
+If subscription is successful the server must respond with `ok` response if no messages are available. The notifier will be receiving the message notifications from this queue until the transport connection is closed or until another transport connection subscribes to notifications from the same simplex queue - in this case the first subscription should be cancelled and [subscription END notification](#subscription-end-notification) delivered.
+
+The first message notification will be delivered either immediately or as soon as the message is available.
+
+### Server messages
+
+#### Queue IDs response
+
+Server must respond with this message when the new queue is created.
+
+See its syntax in [Create queue command](#create-queue-command)
+
+#### Deliver queue message
+
+The server must deliver messages to all subscribed simplex queues on the currently open transport connection. The syntax for the message delivery is:
+
+```abnf
+message = %s"MSG " msgId SP timestamp SP encryptedMsgBody
+encryptedMsgBody = <encrypt paddedSentMsgBody> ; server-encrypted padded sent msgBody
+paddedSentMsgBody = <padded(sentMsgBody, maxMessageLength + 2)> ; maxMessageLength = 16088
+msgId = length 24*24OCTET
+timestamp = 8*8OCTET
+```
+
+`msgId` - unique message ID generated by the server based on cryptographically strong random bytes. It should be used by the clients to detect messages that were delivered more than once (in case the transport connection was interrupted and the server did not receive the message delivery acknowledgement). Message ID is used as a nonce for server/recipient encryption of message bodies.
+
+`timestamp` - system time when the server received the message from the sender as **a number of seconds** since Unix epoch (1970-01-01) encoded as 64-bit integer in network byte order. If a client system/language does not support 64-bit integers, until 2106 it is safe to simply skip the first 4 zero bytes and decode 32-bit unsigned integer (or as signed integer until 2038).
+
+`paddedSentMsgBody` - see syntax in [Send message](#send-message)
+
+When server delivers the messages to the recipient, message body should be encrypted with the secret derived from DH exchange using the keys passed during the queue creation and returned with `queueIds` response.
+
+This is done to prevent the possibility of correlation of incoming and outgoing traffic of SMP server inside transport protocol.
+
+#### Notifier queue ID response
+
+Server must respond with this message when queue notifications are enabled.
+
+See its syntax in [Enable notifications command](#enable-notifications-command)
+
+#### Deliver message notification
+
+The server must deliver message notifications to all simplex queues that were subscribed with `subscribeNotifications` command ("NSUB") on the currently open transport connection. The syntax for the message notification delivery is:
+
+```abnf
+messageNotification = %s"NMSG"
+```
+
+Message notification does not contain any message data or meta-data, it only notifies that the message is available.
+
+#### Subscription END notification
+
+When another transport connection is subscribed to the same simplex queue, the server should unsubscribe and to send the notification to the previously subscribed transport connection:
+
+```abnf
+unsubscribed = %s"END"
+```
+
+No further messages should be delivered to unsubscribed transport connection.
+
+#### Error responses
+
+- incorrect block format, encoding or signature size (`BLOCK`).
+- missing or different session ID - tls-unique binding of TLS transport (`SESSION`)
+- command errors (`CMD`):
+  - error parsing command (`SYNTAX`)
+  - prohibited command (`PROHIBITED`) - any server response sent from client or `ACK` sent without active subscription or without message delivery.
+  - transmission has no required signature or queue ID (`NO_AUTH`)
+  - transmission has unexpected credentials (`HAS_AUTH`)
+  - transmission has no required queue ID (`NO_QUEUE`)
+- authentication error (`AUTH`) - incorrect signature, unknown (or suspended) queue, sender's ID is used in place of recipient's and vice versa, and some other cases (see [Send message](#send-message) command).
+- message queue quota exceeded error (`QUOTA`) - too many messages were sent to the message queue. Further messages can only be sent after the recipient retrieves the messages.
+- sent message is too large (> 16088) to be delivered (`LARGE_MSG`).
+- internal server error (`INTERNAL`).
+
+The syntax for error responses:
+
+```abnf
+error = %s"ERR " errorType
+errorType = %s"BLOCK" / %s"SESSION" / %s"CMD " cmdError / %s"AUTH" / %s"LARGE_MSG" /%s"INTERNAL"
+cmdError = %s"SYNTAX" / %s"PROHIBITED" / %s"NO_AUTH" / %s"HAS_AUTH" / %s"NO_ENTITY"
+```
+
+Server implementations must aim to respond within the same time for each command in all cases when `"ERR AUTH"` response is required to prevent timing attacks (e.g., the server should perform signature verification even when the queue does not exist on the server or the signature of different size is sent, using any RSA key with the same size as the signature size).
+
+### OK response
+
+When the command is successfully executed by the server, it should respond with OK response:
+
+```abnf
+ok = %s"OK"
+```
+
+## Appendices
+
+### Appendix A.
+
+**SMP transport protocol.**
+
+Both the recipient and the sender can use TCP or some other, possibly higher level, transport protocol to communicate with the server. The default TCP port for SMP server is 5223.
+
+For scenarios when meta-data privacy is critical, it is recommended that clients:
+- communicating over Tor network,
+- establish a separate connection for each SMP queue,
+- send noise traffic (using PING command).
+
+In addition to that, the servers can be deployed as Tor onion services.
+
+The transport protocol should provide the following:
+- server authentication (by matching server certificate hash with `serverIdentity`),
+- forward secrecy (by encrypting the traffic using ephemeral keys agreed during transport handshake),
+- integrity (preventing data modification by the attacker without detection),
+- unique channel binding (`sessionIdentifier`) to include in the signed part of SMP transmissions.
+
+By default, the client and server communicate using [TLS 1.3 protocol][13] restricted to:
+- TLS_CHACHA20_POLY1305_SHA256 cipher suite (for better performance on mobile devices),
+- ed25519 and ed448 EdDSA algorithms for signatures,
+- x25519 and x448 ECDHE groups for key exchange.
+- servers must send the chain of exactly 2 self-signed certificates in the handshake, with the first (offline) certificate one signing the second (online) certificate. Offline certificate fingerprint is used as a server identity - it is a part of SMP server address.
+- The clients must abort the connection in case a different number of certificates is sent.
+- server and client TLS configuration should not allow resuming the sessions.
+
+During TLS handshake the client must validate that the fingerprint of the online server certificate is equal to the `serverIdentity` the client received as part of SMP server address; if the server identity does not match the client must abort the connection.
+
+Once TLS handshake is complete, client and server will exchange blocks of fixed size (16384 bytes).
+
+The first block sent by the server should be `serverHello` and the client should respond with `clientHello` - these blocks are used to agree SMP protocol version:
+
+```abnf
+serverHello = minSmpVersion maxSmpVersion sessionIdentifier pad
+minSmpVersion = smpVersion
+maxSmpVersion = smpVersion
+sessionIdentifier = length *OCTET
+; unique session identifier derived from transport connection handshake
+; it should be included in all SMP transmissions sent in this transport connection.
+
+clientHello = smpVersion pad
+; chosen SMP protocol version - it must be the maximum supported version
+; within the range offered by the server
+
+smpVersion = 2*2OCTET ; Word16 version number
+
+pad = *OCTET
+```
+
+For TLS transport client should assert that `sessionIdentifier` is equal to `tls-unique` channel binding defined in [RFC 5929][14] (TLS Finished message struct); we pass it in `serverHello` block to allow communication over some other transport protocol (possibly, with another channel binding).
+
+[1]: https://en.wikipedia.org/wiki/Man-in-the-middle_attack
+[2]: https://en.wikipedia.org/wiki/End-to-end_encryption
+[3]: https://en.wikipedia.org/wiki/QR_code
+[4]: https://en.wikipedia.org/wiki/Unidirectional_network
+[5]: https://en.wikipedia.org/wiki/Forward_secrecy
+[6]: https://en.wikipedia.org/wiki/Off-the-Record_Messaging
+[8]: https://tools.ietf.org/html/rfc5234
+[8a]: https://tools.ietf.org/html/rfc7405
+[9]: https://tools.ietf.org/html/rfc4648#section-4
+[10]: https://tools.ietf.org/html/rfc3339
+[11]: https://tools.ietf.org/html/rfc5280
+[12]: https://tools.ietf.org/html/rfc7714
+[13]: https://datatracker.ietf.org/doc/html/rfc8446
+[14]: https://datatracker.ietf.org/doc/html/rfc5929#section-3
+[15]: https://www.rfc-editor.org/rfc/rfc8709.html
+[16]: https://nacl.cr.yp.to/box.html

protocol/simplex-uri-request.txt

@@ -0,0 +1,18 @@
+Scheme name: simplex
+
+Status: Provisional
+
+Applications/protocols that use this scheme name:
+This scheme is used for connection requests in SimpleX Agent Protocol,
+a middle layer protocol for managing bi-directional communication via
+redundant unidirectional SimpleX Messaging Protocol queues.
+
+Contact: Evgeny Poberezkin <ep@simplex.chat>
+
+Change controller: Evgeny Poberezkin <ep@simplex.chat>
+
+References:
+The syntax for connection requests in the latest version of SimpleX Agent Protocol:
+https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md#connection-request
+SimpleX Messaging Protocol:
+https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md

protocol/smp-uri-request.txt

@@ -0,0 +1,16 @@
+Scheme name: smp
+
+Status: Provisional
+
+Applications/protocols that use this scheme name:
+This scheme is used for URIs of message queues in SimpleX Messaging Protocol,
+a client-server protocol for asynchronous distributed unidirectional
+message transmission via persistent message queues.
+
+Contact: Evgeny Poberezkin <ep@simplex.chat>
+
+Change controller: Evgeny Poberezkin <ep@simplex.chat>
+
+References:
+The syntax for message queue URIs in the latest version of SimpleX Messaging Protocol:
+https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#smp-queue-uri

rfcs/2021-02-28-streams.md

@@ -0,0 +1,48 @@
+# Streams
+
+Managing dedicated SMP queues for fast synchronous communication
+
+## Problem
+
+SMP agent protocol implementation provides the most secure way to distribute keys achieving the following qualities:
+
+- compromising the sender agent/device allows to send messages, but not to read them.
+- compromising the recipient agent/device allows to receive messages, but not to send them (neither public encryption key is stored - TBC if public key can be restored from the private - nor server authentication key is available).
+- compromising the server does not expose any information about messages content, as encrypted section has the same size.
+
+The current hybrid encryption scheme uses a new symmetric key for each message, and because the symmetric key is not persisted at any point, it is difficult to obtain it and send counterfeit messages on behalf of the sender (even in case both the server and recipient are compromised).
+
+There are 2 downsides of the current scheme:
+
+1. RSA encryption/decryption is relatively slow even for 2048 key size and gets much slower for larger key sizes. It is not a problem for the chat messages (and any content updates) that happen infrequently, but it makes the transmission of large files and any other streaming communication slow.
+
+2. If the large file or voice/video calls were to be sent via the same queue as normal messages/content updates, the server and any passive observer would be able to understand when such transmissions happen (even if performance was not a problem).
+
+## Proposed solution
+
+For every fast/dense data transmission use a separate short-lived connection with dedicated SMP queues that the agents would provision to receive such transmissions.
+
+Such connections that can be unidirectional or duplex can be managed by agents via additional set of agent commands using "stream" abstraction.
+
+The protocol to create and manage such stream could be the following:
+
+1. The sender client notifies the agent about the stream it has to create for a specific duplex connection (the connection must be duplex for it to be possible): `<conn_id> SNEW <size>` (where `conn_id` is the existing duplex connection, `size` is the size for the data to be transferred; 0 for unbounded streams), the response is `<conn_id> STREAM <stream_id> <size>`.
+2. The sender agent sends to the recipient agent the "envelope" `STREAM <stream_id> <size>`
+3. The receiving agent would notify the client about availability of the stream by sending `<conn_id> STREAM <stream_id> <size>` notification.
+4. Receiving client would send `<conn_id> SJOIN <stream_id>` command to the receiving agent.
+5. Receiving agent provisions the SMP queue on the random SMP server (we planned to remove SMP server from NEW command anyway). Possibly, there will be a limited list of servers that support streams (that is un-throttled number of messages), and stream support can be communicated via welcome header and change with AUTH SMP command.
+6. Receiving agent sends the envelop to sending agent `SJOIN <stream_id> <invitation>` (where invitation has the same format as in out-of-band message, but it has symmetric AES key and IV instead of asymmetric RSA key - the encryption scheme should codified in the invitation to make it generic).
+7. Sending agent and receiving agent confirm and secure SMP queue as usual. This is still not solving the problem that the sending agent should sign each command. We might extend SMP protocol to create a new queue type that allows authenticating the sender only once per TCP session so that messages can be sent without signing - the server can see that these queues are special anyway, as there will be much faster traffic there.
+8. Sending agent, once the queue is confirmed notifies the sending client that the stream is ready to accept data by sending notification `<conn_id> SREADY <stream_id> <max_chunk_size>`.
+9. Sending agent client can now send packets into the stream up to total `<size>` limit if it was specified by using command `<conn_id> SPUT <stream_id> <chunk_no> <chunk_size> <binary> ` (the chunk size should not be bigger than `max_chunk_size`, the agent would pad it to this size before sending to the receiving agent)
+10. Sending agent would send the chunk to the receiving agent in `CHUNK <chunk_no> <ts> <chunk_size> <binary>` envelope, where the first 4 bytes in decrypted binary is chunk size.
+11. Receiving agent would send the chunk to the client as `<conn_id> SDATA <stream_id> <chunk_no> <ts> <status> <chunk_size> <binary>` (possibly, with three IDs and timestamps as with messages).
+12. Both the receiving and sending clients can terminate the stream with `<conn_id> SCLOSE <stream_id>` command. The agent would send `SCLOSED <stream_id>` envelope and the opposite client would receive `<conn_id> SCLOSED <stream_id>` notification - no more data will be accepted into this stream.
+13. If the stream was bounded with some `size` then both the sending and receiving client would receive `SCLOSED` notification after the last chunk of correct size was sent (and the incorrect chunk would be rejected).
+14. If the stream was interrupted then the recipient client can request resuming this stream using `<conn_id> SRESUME <stream_id> <from_chunk_no>`, the recipient agent would send "envelope" `SRESUME <stream_id> <from_chunk_no> <invitation>`.
+
+To be clarified:
+1. Possibly the internal stream ID used by clients should be different from stream ID communicated between agents, and in any case it should be connection scoped (same as with messages).
+2. There seems to be no need to rotate symmetric keys, disconnections can be handled.
+3. Same as we plan for redundant SMP queues with one connection, agents could use multiple queues per stream to increase the bandwidth and/or transmission reliability (e.g. for file transfers, where interruptions are not problematic multiple queues can be used in parallel, while for calls agents can duplicate all transmitted bytes so that losing some queues or TCP disconnects do not result in communication interruption).
+4. Possibly the stream creation could be initiated by the receiving agent, to have it more similar to connection creation procedure.

rfcs/2021-05-17-open-connection.md

@@ -0,0 +1,52 @@
+# Open connections
+
+## Problem
+
+This proposal describes how to create invitations that can be used multiple times. 
+
+It can be used for:
+- an open invitation to join a group.
+- an open invitation to connect to a person - e.g. QR code/invitation link on a person's website, or passed from one person to another.
+- part of the solution for public DNS-based addresses (when a directory server would map address in some domain name#example.tld to an open invitation).
+
+## Solution
+
+No changes to SMP protocol - a dedicated unsecured SMP queue is used to receive invitations to connect that are sent in encrypted agent message. An unsecured SMP queue is used as an out-of-band channel for establishing another SMP queue.
+
+Additional parameters in commands in SMP agent protocol:
+
+- `NEW` command will have a parameter `INV` or `CON` to create an invitation or a permanent contact connection.
+
+`conn_id? OPEN` (or `PUB`, `NEWPUB`, tbc) - to create an "open"/"public" queue, the response is an invitation in a different format (TBC):
+  - should allow multiple servers (probably the original invitation should be extended to support it)
+  - should have a marker to indicate it's an open/public queue (probably the original invitation should be extended to include an invitation type).
+
+e.g. `smp:<queue_type>::<server1>/<queue_id1>,<server2>/<queue_id2>::<key1>`
+
+`queue_type`:
+  - `prv` - original invitation, should be accepted with KEY SMP message
+  - `pub` - open invitation, should be accepted with INV SMP message (to be added to SMP protocol)
+
+```mmd
+A ->> AA: oidA? OPEN
+AA ->> A: oidA INV pub_inv
+
+...
+
+B ->> BA: cidBA? JOIN pub_inv len CRLF meta_binary CRLF ; change command to require meta, len can be 0 for the current usage ; meta is used to send user profile
+BA ->> B: cidBA OK
+BA ->> SA ->> AA: INV prv_inv CRLF meta_binary
+AA ->> A: oidA CONF invID len meta_binary
+A ->> AA cidAB? LET invID
+
+establish connection as usual
+
+BA ->> B: cidBA CON
+AA ->> A: cidAB CON
+```
+
+That protocol requires addressing the current problem when an invitation cannot be accepted when the party that generated the invitation is not online.
+
+Questions.
+
+1. Do we need to differentiate the semantics of the invitation on the syntax level, or should we allow to just manage it outside of protocol when the receiving agent decides which SMP messages to accept and which to ignore (KEY / INV).

rfcs/2022-03-22-nofication-server.md

@@ -0,0 +1,91 @@
+# Notification server
+
+## Background and motivation
+
+SimpleX Chat clients should receive message notifications when not being online and/or subscribed to SMP servers.
+
+To avoid revealing identities of clients directly to SMP servers via any kind of push notification tokens, a new party called SimpleX Notification Server is introduced to act as a service for subscribing to SMP server queue notifications on behalf of clients and sending push notifications to them.
+
+## Proposal
+
+TCP service using the same TLS transport as SMP server, with the fixed size blocks (256 bytes?) and the following set of commands:
+
+### Protocol
+
+#### Create subscription
+
+Command:
+
+`%s"CREATE " ntfSmpQueueURI ntfPrivateKey token subPublicKey`
+
+Response:
+
+`s%"OK"`
+
+#### Check subscription status
+
+Command:
+
+`%s"CHECK " ntfSmpQueueURI`
+
+Response:
+
+```abnf
+statusResp = %s"STAT " status
+status = %s"ERR AUTH" / "ERR SMP AUTH" / %s"ERR SMP TIMEOUT" / %s"ACTIVE" / %s"PENDING"
+```
+
+#### Update subscription device token
+
+Command:
+
+`%s"TOKEN " ntfSmpQueueURI token`
+
+Response:
+
+`s%"OK" / %s"ERR"`
+
+#### Delete subscription (e.g. when deleting the queue or moving to another notification server)
+
+Command:
+
+`%s"DELETE " SP ntfSmpQueueURI`
+
+Response:
+
+`s%"OK" / %s"ERR"`
+
+### Agent schema changes
+
+See [migration](../src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20220322_notifications.hs)
+
+### Agent code
+
+```haskell
+data NtfOptions = NtfOptions
+  { ntfServer :: Server, -- same type as for SMP servers, probably will be renamed
+    ntfToken :: ByteString,
+    ntfInitialCheckDelay :: Int, -- initial check delay after subscription is created, seconds
+    ntfPeriodicCheckInterval :: Int -- subscription check interval, seconds
+  }
+
+data AgentConfig = AgentConfig {
+  -- ...
+  initialNtfOpts :: Maybe NtfOptions
+  -- ...
+  }
+
+data AgentClient = AgentClient {
+  -- ...
+  ntfOpts :: TVar (Maybe NtfOptions)
+  -- ...
+  }
+```
+
+A configuration parameter `initialNtfOpts :: Maybe NtfOptions` - if it is set or changes the agent would automatically manage subscriptions as SMP queues are subscribed/created/deleted and as the token or server changes.
+
+There will be a method to update notifications configuration in case token or server changes.
+
+All subscriptions will be managed in a separate subscription management loop, that would always take the earliest un-updated subscription that requires some action (ntf_sub_action column) and perform this action - the table of subscription would serve both as the table of existing subscriptions and required actions.
+
+E.g. if the queue is subscribed and there is no notification subscription, it will be created in the table with "create" action, and the loop would create it and schedule "check" action on it.

rfcs/2022-04-20-smp-conf-timeout-recovery.md

@@ -0,0 +1,21 @@
+# SMP confirmation timeout recovery
+
+## Problem
+
+When sending an SMP confirmation a network timeout can lead to the following race condition:
+- server receives the confirmation while the joining party fails to receive the server's response;
+- joining party deletes the connection together with credentials sent in the confirmation for securing the queue;
+- initiating party will receive the confirmation from the server and secure the queue;
+- on subsequent attempt to join via the same invitation link initiating party will generate new credentials and fail authorization.
+
+This renders the joining party permanently unable to join via that invitation link and complete the connection.
+
+## Solution
+
+A possible solution is to keep and try to reuse same credentials on subsequent attempts:
+- joining party has to remember invitation link when saving the connection;
+- if SMP confirmation fails due to network timeout joining party doesn't delete the connection and keeps the credentials;
+- when joining, joining party checks whether such invitation link was already used for a connection, if yes:
+  - joining party tries to send SMP confirmation with the same credentials;
+  - if this SMP confirmation fails with authorization error (for example it can happen due to race condition explained above) joining party tries to send HELLO message;
+  - if HELLO message fails with authorization error (it can happen if connection was deleted or secured with different credentials), the recovery is no longer possible and connection can be deleted.

rfcs/done/2021-01-20-logging.md

@@ -0,0 +1,70 @@
+# SMP agent logging
+
+## Problem and proposed solution.
+
+SMP agent performs multiple actions in response to the client commands and to the messages received from other SMP agents (wrapped in SMP protocol messages).
+
+Customary approach for the network protocol clients is to have a debug/verbose mode that enables logging of all sent and received messages and any other actions that the client performs.
+
+This document proposes a logging format for SMP agent that would be enabled if the agent is run with `--verbose` / `-v` command line option.
+
+We can also consider logging the database operations that change the data.
+
+## Types of actions and the associated log line format.
+
+### Client connected / disconnected
+
+```
+client n connected to Agent
+client n disconnected from Agent
+```
+
+where `n` is a sequential number of a connected agent client, starting from 1 (over the agent run-time).
+
+### Server connected / disconnected
+
+```
+Agent connected to host:port
+Agent disconnected from host:port
+```
+
+### Received command from the client
+
+```
+n --> A : corrId connId parsed_command // raw_command
+```
+
+`raw_command` is added only in case of parsing failure.
+
+### Sent command to SMP server
+
+```
+A --> host:port : corrId queueId parsed_command
+```
+
+### Received response / message from the SMP server
+
+```
+A <-- host:port : corrId queueId parsed_command // raw_command
+```
+
+In case the response is a message or notification, corrId should be replaced with `_`
+
+### Interpreted ("unwrapped") SMP message as agent message
+
+```
+Agent msg : connId parsed_message // raw_message 
+```
+
+### Sent response / message to the client
+
+```
+n <-- A : corrId connId parsed_command // raw_command
+```
+
+### Database changes
+
+```
+DB : insert/delete/update table key
+DB : insert/delete/update table key
+```

rfcs/done/2021-01-26-crypto.md

@@ -0,0 +1,192 @@
+# SMP agent: cryptography
+
+3 main directions of work to enable basic level of security for communication via SMP agents and servers at the current stage of the project:
+
+- Transport encryption - enable encryption for TCP.
+
+- Initial handshake using asymmetric key pairs, starting with out-of-band message.
+
+- E2E encryption of messages between SMP agents relayed over SMP servers.
+
+- Authentication of agent commands with SMP servers.
+
+For initial implementation I propose approach to be as simple as possible as long as it meets our security requirements. So no pluggable encryption mechanisms, no configuration, no integration with [Noise Protocol Framework](https://noiseprotocol.org), only the most necessary Crypto schemes pre-decided per area of application.
+
+## Transport encryption
+
+One of the consideration is to use [noise protocol framework](https://noiseprotocol.org/noise.html), this section describes ad hoc protocol though.
+
+During TCP session both client and server should use symmetric AES 256 bit encryption using two session keys and two base IVs that will be agreed during the handshake. Both client and the server should maintain two 32-bit word counters, one for sent and one for the received messages. The IV for each message should be computed by xor-ing the sequential message counter, starting from 0, with the first 32 bits of agreed base IV. TODO - explain it in a more formal way, also document how 32-bit word is encoded - with the most or least significant byte first (currently encodeWord32 from Network.Transport.Internal is used)
+
+To establish the session keys and base IVs, the server should have an asymmetric key pair generated during server deployment and unknown to the clients. The users should know the key hash (256 bits) in advance in order to be able to establish connection.
+
+The handshake sequence is the following:
+
+1. Once the connection is established, the server sends server_header and its public RSA key encoded in X509 binary format to the client.
+2. The client compares the hash of the received key with the hash it already has (e.g. received as part of connection invitation or server in NEW command). If the hash does not match, the client must terminate the connection. TODO as the hash is optional in server syntax at the moment, hash comparison will be optional as well. Probably it should become required.
+3. If the hash is the same, the client should generate random symmetric AES keys and base IVs that will be used as session keys/IVs by the client and the server.
+4. The client then should construct client_handshake block and send it to the server encrypted with the server public key: `rsa-encrypt(client_handshake)`. `snd_aes_key` and `snd_base_iv` will be used by the client to encrypt **sent** messages and by the server to decrypt them, `rcv_aes_key` and `rcv_base_iv` will be used by the client to decrypt **received** messages and by the server to encrypt them.
+5. The server should decrypt the received keys and base IVs with its private key.
+6. In case of successful decryption, the server should send encrypted welcome block (encrypted_welcome_block) that contains SMP protocol version.
+
+All the subsequent data both from the client and from the server should be sent encrypted using symmetric AES keys and base IVs (incremented by counters on both sides) sent by the client during the handshake.
+
+Each transport block sent by the client and the server has this syntax:
+
+```abnf
+server_header = block_size protocol key_size
+block_size = 4*4(OCTET) ; 4-byte block size sent by the server, currently the client rejects if > 65536 bytes
+protocol = 2*2(OCTET) ; currently it is 0, that means binary RSA key
+key_size = 2*2(OCTET) ; the encoded key size in bytes (binary encoded in X509 standard)
+
+client_handshake = client_block_size client_protocol snd_aes_key snd_base_iv rcv_aes_key rcv_base_iv
+client_block_size = 4*4(OCTET) ; 4-byte block size sent by the client, currently it is ignored by the server - reserved
+client_protocol = 2*2(OCTET) ; currently it is 0 - reserved
+snd_aes_key = 32*32(OCTET)
+snd_base_iv = 16*16(OCTET)
+rcv_aes_key = 32*32(OCTET)
+rcv_base_iv = 16*16(OCTET)
+
+transport_block = aes_body_auth_tag aes_encrypted_body
+; size is sent by server during handshake, usually 8192 bytes
+aes_encrypted_body = 1*OCTET
+aes_body_auth_tag = 16*16(OCTET)
+
+encrypted_welcome_block = transport_block
+welcome_block = smp_version SP pad ; decrypt(encrypted_welcome_block)
+smp_version = %s"v" 1*DIGIT "." 1*DIGIT "." 1*DIGIT ["-" 1*ALPHA "." 1*DIGIT] ; in semver format
+  ; for example: v123.456.789-alpha.7
+pad = 1*OCTET
+```
+
+## Possible future improvements/changes
+
+- server id (256 bits), so that only the users that have it can connect to the server. This ID will have to be passed to the server during the handshake
+- block size agreed during handshake
+- transport encryption protocol agreed during handshake
+- welcome block containing SMP mode (smp_mode)
+
+```abnf
+smp_mode = smp_public / smp_authenticated
+smp_public = %s"pub" ; public (default) - no auth to create and manage queues
+smp_authenticated = %s"auth" ; server authentication with AUTH command (TBD) is required to create and manage queues
+```
+
+## Initial handshake
+### Why handshake has to be with asymmetric keys
+
+The following only makes sense under the assumption that public keys are not really used as "public", but are created as random and treated as secret instead.
+
+    E controls servers & listens out-of-band.
+    Keys are generated on the clients (A & B), queues are generated on servers.
+    1. A generates Apub, Aprv, BAq
+    2. A --oob-> B: Apub, BAq; E listens this, however she can't substitute this (passive attack on out-of-band, active on servers)
+    3. E generates EpubA, EprvA, AEq
+    4. E --BAq-> A: EpubA, AEq - encrypted with Apub;
+    Alice thinks this message is from Bob
+    5. B generates Bpub, Bprv, ABq
+    6. B --BAq-> ~~A~~E: Bpub, ABq - encrypted with Apub;
+    Eve controls servers so this doesn't get sent to Alice, instead it is received by Eve
+    7. Eve has to send to Bob via ABq encrypting with his Bpub. By controlling servers E could know ABq so she wouldn't have to decrypt it - she knows where to send. Even so she can't decrypt Bpub w/t Aprv. The problem [for Eve] is that Bpub and Aprv are generated on the clients, which she doesn't control.
+
+If keys were symmetric Eve could simply decrypt Bob's key with the key Alice sent out-of-band.
+
+### Where MITM attempt fails
+
+In asymmetric setup the following happens:
+
+- In Bob to Alice direction Eve intercepts messages from Bob and re-encrypts them using Apub.
+
+- In Alice to Bob direction Alice encrypts messages with EpubA and Eve can decrypt them with EprvA. Eve can't, however, re-encrypt them for Bob because she doesn't know Bpub. She also couldn't substitute it because it is out of her control. Alice wouldn't [technically] notice the MITM attempt, but Bob will not be receiving decryptable messages, and he would have to tell Alice out-of-band.
+
+> **To be discussed:** Implementation-wise Bob's connection probably should be shut down if he receives a message he fails to decrypt, or after some timeout if he doesn't receive messages.
+
+### Handshake implementation
+
+TODO
+
+## E2E encryption
+
+For E2E encryption of messages between SMP agents we should go with some robust [Authenticated Encyption](https://en.wikipedia.org/wiki/Authenticated_encryption) scheme following [Encrypt-then-MAC](https://en.wikipedia.org/wiki/Authenticated_encryption#Encrypt-then-MAC_(EtM)) approach.
+
+Since we have a shared secret Apub, Bpub (if Apub is compromised connection should be shut down on Bob's side, see [above](#-Where-MITM-attempt-fails)) there is no point in using digital signatures over MACs for message authentication other than non-repudiation. Besides [digital signatures generally being less performant than MACs](https://crypto.stackexchange.com/a/37657), the non-repudiation quality I believe may in fact be more undesirable than not for many possible applications. If some applications require non-repudiation it can be implemented later on with digital signatures on application level. See a good answer on differences of MAC and digital signature qualities [here](https://crypto.stackexchange.com/a/5647).
+
+Symmetric keys are generated per message and encrypted with receiver's public key (encryption key).
+
+The syntax of each encrypted message body is the following:
+
+```abnf
+encrypted_message_body = rsa_signature encrypted_body
+encrypted_body = rsa_encrypted_header aes_encrypted_body
+rsa_signature = 256*256(OCTET) ; sign(encrypted_body) - assuming 2048 bit key size
+rsa_encrypted_header = 256*256(OCTET) ; encrypt(header) - assuming 2048 bit key size
+aes_encrypted_body = 1*OCTET ; encrypt(body)
+
+header = aes_key aes_iv auth_tag payload_size
+aes_key = 32*32(OCTET)
+aes_iv = 16*16(OCTET)
+auth_tag = 16*16(OCTET)
+payload_size = 4*4(OCTET)
+
+body = payload pad
+```
+
+Future considerations:
+- Generation of symmetric keys per session and session rotation;
+
+## E2E implementation
+
+### Message encryption
+
+For each message, the agent performs the following actions to encrypt it:
+
+1. Generates random AES256 key with [getRandomBytes]() - see [tutorial](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-Tutorial.html)
+2. Pad the message using some padding scheme TBC - we could consider [PADMÉ](https://petsymposium.org/2019/files/papers/issue4/popets-2019-0056.pdf), but there is no existing implementation. This particular scheme is protected against both understanding the nature of the traffic and has low overhead (< 12%). There are various other padding schemes described [here](https://en.wikipedia.org/wiki/Padding_(cryptography)) - the proposal is to postpone this decision and not to include any padding in the chat prototype to be released.
+3. Encrypt the message using this AES256 key with [AES-GCM-SIV](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-Cipher-AESGCMSIV.html) (AEAD scheme) using the function `encrypt` with a random nonce.
+4. Encrypt the AES256 key with public encryption key for the queue using RSA-OAEP [encrypt](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-PubKey-RSA-OAEP.html#v:encrypt) function parameterized with [SHA256](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-Hash-Algorithms.html#t:SHA256) algorithm.
+5. The message to send is concatenation of:
+    1. encrypted AES256 key,
+    2. AuthTag from encryption in step 3, 
+    3. encrypted message (in this order).
+
+As there is no additional data that is sent e2e in clear text, we potentially need some simpler algorithm, possibly the one implemented in the tutorial, that implements authenticated encryption without additional (unencrypted) data.
+
+Or we could use this algorithm to allow some data that is sent e2e in clear text later.
+
+### Message decryption
+
+Agent decrypts the message following the same steps in the opposite order:
+
+1. Split encrypted message to AES256 key, AuthTag and encrypted message - tag and key have fixed size (?).
+2. Decrypt AES256 key using the decryption key (the private key that recipient has).
+3. Decrypt the message using AES256 key.
+4. Remove the padding - scheme TBC, not in the initial implementation.
+
+## Authentication with SMP server
+
+Each command sent to the server should include digital signature in the first part of the SMP transmission.
+
+To compute the signature, the agent will use [signSafer](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-PubKey-RSA-PSS.html#v:signSafer) function parameterized with [SHA256](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-Hash-Algorithms.html#t:SHA256) algorithm with the "signed" part of the transmission.
+
+To verify the signature, the server will use [verify](https://hackage.haskell.org/package/cryptonite-0.28/docs/Crypto-PubKey-RSA-PSS.html#v:verify) function with the same hash algorithm.
+
+The above implies that the way the transmissions are processed should change.
+
+It is simpler during the sending, because it is possible to serialise signed part, prepend the signature and then send it.
+
+It is more difficult during the receiving because to read the whole transmission it has to be parsed first (in order to have the size of the message in SEND command and to read the remaining binary), then serialized back, and only after it the signature can be verified. Possible solution is to have both unparsed and parsed transmission in some data structure (e.g. tuple) to avoid unnecessary serialisation.
+
+The proposed change is also to change SMP protocol in this way:
+1. to have components of a signed transmission part on a single line, space-separated, rather than on multiple lines (to avoid byte-string differences because of different presentation of the end of line)
+2. the separation between SEND and binary part does not matter as binary is read separately and can be consistently appended with CRLF (arguably, it also applies to the rest of transmission part, but it is just simpler to read and parse one line and then append binary, if necessary, for signature verification).
+
+```abnf
+transmission = [signature] CRLF signed CRLF
+signed = [corrId] SP [queueId] SP msg
+```
+
+Off topic: SMP agent protocol can also be similarly changed to align with SMP protocol.
+
+## Concerns
+
+- MITM between SMP agent and server is still possible w/t transport encryption.

rfcs/done/2021-01-26-messages.md

@@ -0,0 +1,33 @@
+# SMP Agent: message management
+
+The proposal is to change the way SMP agent manages the messages from the SMP servers.
+
+Currently, it acts just as a proxy, when it does not receive any further messages from the server until the client ACKs them. The downside with this approach is that the agent can't work autonomously from the client, and the client always has to be active to retrieve the messages from the server. So while the agent offers a convenient, higher abstraction level when it comes to establishing connections, it does not offer any advantage over message management than using SMP server directly. There is a benefit to have an agent as a local, mailbox-like layer that downloads all messages for all connections and makes them available for further processing on the application layer.
+
+## Phase 1. Managed agent MVP
+
+These should be sufficient for terminal chat prototype
+
+- Agent only maintains active subscriptions to the connections that the clients explicitly requested, only during client sessions, using `SUB` command.
+- Agent would automatically send `ACK` commands to SMP servers and store them in the database.
+- When the client subscribes to the connection (`SUB` - subscribe and deliver all messages received from the server) the response to `SUB` command is `OK`.
+- Receiving agent should maintain its own numbering in addition to the sending agent numbering, in case the sending agent message number decreases.
+- When there is an active subscription, Agent forwards messages to the connected clients in the order of their arrival, without any confirmations from the clients. It is client's responsibility to track that they didn't miss any messages and request re-delivery if needed.
+
+## Phase 2. Subscription management and message access
+
+- When the client subscribes to the connection (`SUB` - subscribe and deliver all missed messages) the response to `SUB` command is `NOMSG` or `MID n` where n is the ID of the last received message (1-based).
+- `SUB SKIP` - subscribe but only deliver the new messages
+- `SUB OFF` - turn off subscription
+- Messages received by the agent during the period when there was no active client subscription are not sent to the client automatically - client has to request them one by one using `MGET n` command (it can also be used to request re-delivery of old messages or for any other direct access scenario).
+- Clients can delete received messages using `MDEL n` command, where `n` is a sequential agent-assigned message ID - same that was used in `MSG` delivery.
+- Clients can confirm the receipt of the messages to the sender using `MACK n` command
+- Client can also request the last message ID with `MLAST` command - with the same responses.
+
+## Phase 3. Autonomous agent
+
+- Agent maintains active subscriptions to all connections that the clients created, whether there are active sessions with the clients or not.
+- `SUB ON` command would be used to receive messages from the agent, and while it is active the agent would maintain an active TCP connection(s) with the server(s) to retrieve the messages as soon as they arrive.
+- In the absence of the client connection the agent would periodically check and retrieve messages from the servers, possibly up to a quota, from all active connections. If the servers do not reply, the agent could have some retry logic with exponential back-off eventually marking connections (and/or servers) as unresponsive.
+
+This design allows to have a single agent running in the background with multiple client applications connecting to it. It provides better message delivery guarantees, assuming transient nature of SMP server storage.

rfcs/protocol_overview.md

@@ -0,0 +1,146 @@
+# Overview of SMP agent protocol commands
+
+## Connections
+
+### Commands and messages
+
+A initiates connection, B accepts
+
+- command `C:idB? NEW` - create connection
+- message `C:idB INV cInv`
+- command `C:idA? JOIN cInv replyMode` - join connection (response `OK`, followed by `CON`)
+- *message* `C:idB REQ prv:invId infoB` - request from B joining sent to A (not implemented)
+- *command* `C:idB ACPT prv:invId` - A confirms B joining (not implemented)
+- message `C:id CON` - connection is established
+- command `C:id SUB` - subscribe to connection
+- message `C:id END` - unsubscribed from connection
+- command `C:idB SEND msg` - send message
+- message `C:idA SENT msgId` - confirmation that the message is sent
+- message `C:id MSG msgId msgMeta msgIntegrity msgBody` - received message
+- *command* `C:idB ACK msgId` - acknowledge message reception (not implemented)
+- *message* `C:idA RCVD msgId msgIntegrity` - confirmation of message reception and integrity (not implemented)
+- command `C:id OFF` - suspend connection
+- command `C:id DEL` - delete connection
+- message `C:id? OK` - command confirmation
+- message `C:id? ERR e` - error
+
+### Envelopes
+
+- `MSG `
+- `HELLO verificationKey ackMode`
+- `REPLY replyInv`
+
+## Broadcasts
+
+### Commands & messages
+
+- command `B:id? NEW` - create broadcast (response is `B:id OK`)
+- command `B:id SEND msg` - broadcast message (response is multiple `C:id SENT msgId` or ERR, separately for each connection, followed by `B:id SENT msgId` once sent to all)
+- message `B:id SENT msgId` - notification that the message is sent and its internal ID, same as SENT
+- command `B:id ADD cId` - add existing connection to a broadcast (response is `B:id OK` or `ERR`, e.g. if bId is used)
+- command `B:id REM cId` - remove connection from the broadcast (response is `REMD`)
+- message `B:id REMD cId` - connection removed from the broadcast
+- message `B:id EMPTY` - all connections were removed from the broadcast
+- command `B:id DEL` - delete broadcast (response is `B:id OK`)
+- command `B:id LS` - list connections in broadcast, response is `B:id MEM space_separated_connections`
+- message `B:id MEM space_separated_connections`
+
+## Open/public connection
+
+### Commands
+
+- command `O:id? NEW` - create open connection
+- message `O:id INV oInv` - open invitation
+- command `C:id? JOIN oInv replyMode` - join connection (response `OK`, followed by `CON`)
+- message `O:id REQ open:invId infoB` - confirmation from B joining sent to A
+- command `C:idC? ACPT open:invId` - note, that it creates new connection, keeping OPEN connection
+- command `O:id SUB` - subscribe to open connection
+- message `O:id END` - unsubscribed from open connection
+- command `O:id OFF` - suspend open connection
+- command `O:id DEL` - delete open connection
+- message `O:id? OK` - command confirmation
+- message `O:id? ERR e` - error
+
+## Introductions
+
+### Commands
+
+- command `C:idAB INTRO C:idAM infoM` - introduce connection cIdB to connection cIdM (response is `OK`)
+- message `C:idBA REQ C:invId infoM` - notification to confirm introduction
+- command `C:idBM? ACPT C:invId` - accept offer to be introduced (response is `cIdBM OK`, followed by `ICON`)
+- message `C:idBM CON` - confirmation that connection is established to both introduced parties
+- message `C:idAB CON C:idAM` - confirmation that connection is established to the introducer
+
+### Envelopes
+
+- `INTRO C:extIntroIdM infoM` - new introduction offered by introducer
+- `INV C:extIntroIdB prv:invBM infoB` - invitation to join connection from B to M sent via A (can be pub:)
+- `REQ C:extIntroIdB prv:invBM infoB` - new introduction forwarded by introducer
+- `CON C:extIntroIdM` - confirmation that the connection is established sent by both introduced parties to the introducer
+
+## Groups
+
+## Agent commands and messages syntax
+
+- command `G:gId? NEW` - create group (response is `G:gId OK`)
+- command `C:cId INTRO G:gId gInfo` - add existing connection to a group
+- message `C:cId REQ g:invID gInfo` - invitation to join the group
+- command `G:gId? ACPT g:invId` - accept invitation (response is `G gId OK`)
+- message `G:gId CON C:cId` - 2 connections created with some group member (both for group and direct messages)
+- message `G:gId MEM [C:cId]` - connection created with all group members for a given member or current client
+- command `G:gId SEND msg` - send message to group
+- message `G:gId SENT msgId` - notification that the message is sent and its internal ID, same as SENT
+- message `G:gId MSG C:cId msgId msgdata` - received group message from cId, msgdata is the same set of parameters as in `MSG`
+- command `G:gId ACK msgId` - acknowledge message reception by the client
+- message `G:gId RCVD t:cId msgId status` - message delivery notification
+- command `G:gId LEAVE` - leave the group
+- message `G:gId LEFT [C:cId]` - connection cId left the group
+- command `G:gId REM C:cId` - remove group member (response is `gId OK`, followed by `GREMD` notification)
+- message `G:gId REMD C:cId [C:cId]` - member removed
+- message `G:gId OUT C:cId` - you are removed (see question below - should it be just a sequence of GLEFT?)
+- message `G:gId EMPTY` - all members left the group and it is now empty
+- command `G:gId DEL` - delete the group (response is `gId OK`)
+- message `G:gId DELD [C:cId]` - group deleted
+
+## Agent message envelopes syntax
+
+- `GROUP C:mid G:inv gInfo` - invitation to join the group
+- `MEM C:mid` - confirmation that member connected to all members
+- `LEFT` - notification that member left the group
+- `OUT` - you are removed from the group
+- `REM C:mid` - remove member mid from the group
+- `REMD C:mid` - confirmation that member is removed
+- `DEL` - group is deleted
+- `DELD` - confirmation that group is deleted
+
+## Commands and objects
+
+| Dir     | Command / message    | (C)onnection | (O)pen connection | (B)roadcast | (G)roup |
+|:---------:|:--------------------:|:------------:|:-----------------:|:-----------:|:-------:|
+| command | `t:id? NEW`           | ✓ | ✓ | ✓ | ✓ |
+| command | `C:id INTRO t:id info` | ✓ | - | - | ✓ |
+| message | `t:id INV inv`        | ✓ | ✓ | - | - |
+| command | `C:id? JOIN inv replyMode info` | ✓ | - | - | - |
+| message | `t:id REQ invId info` | ✓ | ✓ | - | ✓ |
+| command | `t:id? ACPT invId`    | ✓ | - | - | ✓ |
+| message | `t:id CON [C:id]`     | ✓ | - | - | ✓ |
+| message | `t:id MEM [C:id]`     | - | - | - | ✓ |
+| command | `t:id SUB`            | ✓ | ✓ | - | ✓ |
+| message | `t:id END`            | ✓ | ✓ | - | ✓ |
+| command | `t:id OFF`            | ✓ | ✓ | - | - |
+| command | `t:id DEL`            | ✓ | ✓ | ✓ | ✓ |
+| message | `t:id DELD [C:Id]`    | ✓ | ✓ | ✓ | ✓ |
+| command | `t:id SEND msg`       | ✓ | - | ✓ | ✓ |
+| message | `t:id SENT [t':id] msgId` | ✓ | - | ✓ | ✓ |
+| message | `t:id MSG [C:id] msgId msgdata` | ✓ | - | - | ✓ |
+| command | `t:id ACK msgId`      | ✓ | - | - | ✓ |
+| message | `t:id RCVD [t':id] msgId status` | ✓ | - | - | ✓ |
+| command | `t:id ADD C:id`       | - | - | - | ✓ |
+| command | `t:id REM C:id`       | - | - | ✓ | ✓ |
+| command | `t:id REMD C:id`      | - | - | ✓ | ✓ |
+| message | `t:id EMPTY`          | - | - | ✓ | ✓ |
+| message | `G:id OUT C:id`       | - | - | - | ✓ |
+| command | `t:id LS`             | - | - | ✓ | ✓ |
+| message | `t:id MS cIds`        | - | - | ✓ | ✓ |
+| command | `G:id LEAVE`          | - | - | - | ✓ |
+| message | `G:id LEFT [C:id]`    | - | - | - | ✓ |

rfcs/rejected/2021-05-23-broadcast.md

@@ -0,0 +1,50 @@
+# SMP agent broadcast
+
+## Problem
+
+Support agent message broadcast to multiple connections.
+
+It is done in ad-hoc way as part of the previous [groups proposal](./2021-05-23-groups2.md) - this proposal defines broadcast as a separate agent primitive to simplify group management.
+
+It can also be used for other purposes when the same message needs to be sent to multiple recipients without creating groups.
+
+## Solution
+
+A minimal protocol of additional client commands to create, manage and use broadcasts.
+
+From the point of view of the recipient this will look like a normal message, as if the sending agent executed multiple send commands (in fact, broadcast can be implemented by agent sending itself multiple SEND commands)
+
+### Commands and messages
+
+- command `B:bId? NEW` - create broadcast (response is `B:bId OK`, or `ERR` if broadcast already exists)
+- command `B:bId ADD C:cId` - add existing connection to a broadcast (response is `B:bId OK` or `ERR`, e.g. if connection already added or does not exist)
+- command `B:bId SEND msg` - broadcast message (response is multiple `B:cId SENT [C:bId] msgId` or ERR, separately for each connection and then for the broadcast)
+- message `B:bId SENT [C:bId] msgId` - notification that the message is sent to a specific or all recipients
+- command `B:bId REM C:cId` - remove connection from broadcast (response is `B:bId OK` or `ERR`)
+- message `B:bId EMPTY` - all connections were removed from the broadcast
+- command `B:bId DEL` - delete broadcast (response is `B:bId OK` and when the last connection is removed an additional `B:bId EMPTY` is sent)
+- command `B:bId LS` - list connections in broadcast, response is `B:Id MS space_separated_connections`
+- message `B:bId MS space_separated_connections`
+
+## Questions
+
+1. Should broadcast IDs use the same namespace as connection IDs (and as group IDs)? Having the same namespace for all abstractions that the agent can operate on can be helpful, as it can also allow implementing some queries to determine which type a given ID has, but it also increases implementation complexity.
+
+2. Given that this abstraction would be used as internal abstraction for groups (same as connections internal to the group), it might be better to implement "agent users", each with its own connection namespace. In this case agent would use itself as one of the users.
+
+3. There is a similarity of commands for connections, groups and broadcasts, they only differ on the single-letter prefix. We could do one of the following:
+  - use the same command for different object types. This feels incorrect and error prone on its own.
+  - extend transmission structure with the field defining the object type (connection, group, broadcast, etc.).
+
+In this case, the transmission would look like:
+
+```
+agentTransmission = [corrId] CRLF objectType:[objectID] CRLF agentCommand
+objectType = C | B | G ; this is the additional field
+```
+
+This approach would allow reusing the existing command avoiding the unnecessary repetition.
+
+In this case, the command type could be parameterized with the list of supported agent object types, so we can ensure on the type level that only allowed commands can be constructed.
+
+EDIT: This approach is already implemented

rfcs/rejected/2021-05-23-introduction.md

@@ -0,0 +1,41 @@
+# SMP agent introduction
+
+## Problem
+
+Allow an agent client to connect two connections it has directly, with the agent acting as an out-of-band channel.
+
+It can be used both separately as part of some client functionality, and as part of group protocol.
+
+## Solution
+
+A protocol with commands and message envelopes to exchange the information between parties to establish connection.
+
+### Commands and messages
+
+Below commands are for the scenario when A introduces B to M.
+
+- command `C:idAB INTRO C:idAM infoM` - initiate introduction of the connection cIdB to connection cIdM (response is `C:idAB OK`)
+- message `C:idBA REQ C:invId infoM` - notification to confirm introduction
+- command `C:idBM? ACPT C:invId` - accept offer to be introduced (response is `C:idBM OK`, followed by `C:idBM CON`)
+- message `C:idBM CON` - confirmation that connection is established to both introduced parties
+- message `C:idAB CON C:idAM` - confirmation that connection is established to the introducer
+
+### Agent envelopes
+
+- `INTRO C:extIntroIdM infoM` - new introduction offered by introducer
+- `INV C:extIntroIdB prv:invBM infoB` - invitation to join connection from B to M sent via A
+- `REQ C:extIntroIdB prv:invBM infoB` - new introduction forwarded by the introducer
+- `CON C:extIntroId` - confirmation that the connection is established sent by both introduced parties to the introducer
+
+## Namespace
+
+Given that the introduction objects are short lived, they should not reuse the same commands or share the same namespace as connections, broadcasts and groups, but they probably should share the namespace with group and connection invitations.
+
+## Introduction protocol costs
+
+5 messages + cost to establish a connection
+
+
+The [sequence digram for introduction](https://mermaid.ink/img/eyJjb2RlIjoic2VxdWVuY2VEaWFncmFtXG4gIHBhcnRpY2lwYW50IEEgYXMgQWxpY2UgKEEpIC0gdGhlIGludHJvZHVjZXJcbiAgcGFydGljaXBhbnQgQUEgYXMgQWxpY2Unczxicj5hZ2VudCAoQUEpXG4gIHBhcnRpY2lwYW50IEIgYXMgQm9iIChCKSAtIGludHJvZHVjZWRcbiAgcGFydGljaXBhbnQgQkEgYXMgQm9iJ3M8YnI-YWdlbnQgKEJBKVxuICBwYXJ0aWNpcGFudCBNIGFzIE1hcmsgKE0pIC0gaW50cm9kdWNlZCB0b1xuICBwYXJ0aWNpcGFudCBNQSBhcyBNYXJrJ3M8YnI-YWdlbnQgKE1BKVxuXG4gIG5vdGUgb3ZlciBBLCBBQTogMS4gY3JlYXRlIGludHJvZHVjdGlvblxuICBBIC0-PiBBQTogQzppZEFCIElOVFJPIEM6aWRBTSBpbmZvTTxicj4oaWRBQiAtIGNvbm4gYWxpYXMgQSBoYXMgZm9yIEIsPGJyPmlkQU0gLSBmb3IgTSlcbiAgQUEgLT4-IEE6IEM6aWRBQiBPS1xuXG4gIG5vdGUgb3ZlciBBLCBCQTogMi4gc2VuZCBpbnRybyB0byBCb2JcblxuICBBQSAtPj4gQkE6IHZpYSBpZEFCOiBJTlRSTyBDOmV4dEludHJvSWRNIGluZm9NXG4gIEJBIC0-PiBCOiBDOmlkQkEgUkVRIEM6aW50SW50cm9JZE0gaW5mb01cbiAgQiAtPj4gQkE6IEM6aWRCTT8gQUNQVCBDOmludEludHJvSWRNXG4gIEJBIC0-PiBCOiBDOmlkQk0gT0tcblxuICBub3RlIG92ZXIgQkE6IDMuIGNyZWF0ZSBjb25uZWN0aW9uIGZvciAgTSBpZEJNXG5cbiAgQkEgLT4-IEFBOiB2aWEgaWRCQTogSU5WIEM6ZXh0SW50cm9JZE0gcHJ2OmludkJNIGluZm9CXG5cbiAgbm90ZSBvdmVyIEFBLCBNOiA0LiBzZW5kIGludHJvIHRvIE1hcmtcblxuICBBQSAtPj4gTUE6IHZpYSBpZEFNOiBSRVEgQzpleHRJbnRyb0lkQiBwcnY6aW52Qk0gaW5mb0JcblxuICBub3RlIG92ZXIgTUEsIEI6IDUuIE1hcmsgY29ubmVjdHMgdG8gQm9iXG5cbiAgTUEgLT4-IE06IEM6aWRNQSBSRVEgQzppbnRJbnRyb0lkQiBpbmZvQlxuICBNIC0-PiBNQTogQzppZE1CPyBBQ1BUIEM6aW50SW50cm9JZEJcbiAgTUEgLT4-IE06IEM6aWRNQiBPS1xuXG4gIE1BIC0-PiBCQTogIGVzdGFibGlzaCBjb25uZWN0aW9uIGlkQk0gLT4gaWRNQlxuXG4gIG5vdGUgb3ZlciBBLCBNQTogNi4gbm90aWZ5IGFsbCBjbGllbnRzXG5cbiAgTUEgLT4-IE06IEM6aWRNQiBDT05cbiAgTUEgLT4-IEFBOiB2aWEgaWRNQTogQ09OIEM6ZXh0SW50cm9JZEJcbiAgQkEgLT4-IEI6IEM6aWRCTSBDT05cbiAgQkEgLT4-IEFBOiB2aWEgaWRCQTogQ09OIEM6ZXh0SW50cm9JZEJcbiAgQUEgLT4-IEE6IEM6aWRBQiBDT04gQzppZEFNXG4iLCJtZXJtYWlkIjp7fSwidXBkYXRlRWRpdG9yIjpmYWxzZX0), the source is [here](./intro.mmd).
+
+![sequence digram for introduction](https://mermaid.ink/svg/eyJjb2RlIjoic2VxdWVuY2VEaWFncmFtXG4gIHBhcnRpY2lwYW50IEEgYXMgQWxpY2UgKEEpIC0gdGhlIGludHJvZHVjZXJcbiAgcGFydGljaXBhbnQgQUEgYXMgQWxpY2Unczxicj5hZ2VudCAoQUEpXG4gIHBhcnRpY2lwYW50IEIgYXMgQm9iIChCKSAtIGludHJvZHVjZWRcbiAgcGFydGljaXBhbnQgQkEgYXMgQm9iJ3M8YnI-YWdlbnQgKEJBKVxuICBwYXJ0aWNpcGFudCBNIGFzIE1hcmsgKE0pIC0gaW50cm9kdWNlZCB0b1xuICBwYXJ0aWNpcGFudCBNQSBhcyBNYXJrJ3M8YnI-YWdlbnQgKE1BKVxuXG4gIG5vdGUgb3ZlciBBLCBBQTogMS4gY3JlYXRlIGludHJvZHVjdGlvblxuICBBIC0-PiBBQTogQzppZEFCIElOVFJPIEM6aWRBTSBpbmZvTTxicj4oaWRBQiAtIGNvbm4gYWxpYXMgQSBoYXMgZm9yIEIsPGJyPmlkQU0gLSBmb3IgTSlcbiAgQUEgLT4-IEE6IEM6aWRBQiBPS1xuXG4gIG5vdGUgb3ZlciBBLCBCQTogMi4gc2VuZCBpbnRybyB0byBCb2JcblxuICBBQSAtPj4gQkE6IHZpYSBpZEFCOiBJTlRSTyBDOmV4dEludHJvSWRNIGluZm9NXG4gIEJBIC0-PiBCOiBDOmlkQkEgUkVRIEM6aW50SW50cm9JZE0gaW5mb01cbiAgQiAtPj4gQkE6IEM6aWRCTT8gQUNQVCBDOmludEludHJvSWRNXG4gIEJBIC0-PiBCOiBDOmlkQk0gT0tcblxuICBub3RlIG92ZXIgQkE6IDMuIGNyZWF0ZSBjb25uZWN0aW9uIGZvciAgTSBpZEJNXG5cbiAgQkEgLT4-IEFBOiB2aWEgaWRCQTogSU5WIEM6ZXh0SW50cm9JZE0gcHJ2OmludkJNIGluZm9CXG5cbiAgbm90ZSBvdmVyIEFBLCBNOiA0LiBzZW5kIGludHJvIHRvIE1hcmtcblxuICBBQSAtPj4gTUE6IHZpYSBpZEFNOiBSRVEgQzpleHRJbnRyb0lkQiBwcnY6aW52Qk0gaW5mb0JcblxuICBub3RlIG92ZXIgTUEsIEI6IDUuIE1hcmsgY29ubmVjdHMgdG8gQm9iXG5cbiAgTUEgLT4-IE06IEM6aWRNQSBSRVEgQzppbnRJbnRyb0lkQiBpbmZvQlxuICBNIC0-PiBNQTogQzppZE1CPyBBQ1BUIEM6aW50SW50cm9JZEJcbiAgTUEgLT4-IE06IEM6aWRNQiBPS1xuXG4gIE1BIC0-PiBCQTogIGVzdGFibGlzaCBjb25uZWN0aW9uIGlkQk0gLT4gaWRNQlxuXG4gIG5vdGUgb3ZlciBBLCBNQTogNi4gbm90aWZ5IGFsbCBjbGllbnRzXG5cbiAgTUEgLT4-IE06IEM6aWRNQiBDT05cbiAgTUEgLT4-IEFBOiB2aWEgaWRNQTogQ09OIEM6ZXh0SW50cm9JZEJcbiAgQkEgLT4-IEI6IEM6aWRCTSBDT05cbiAgQkEgLT4-IEFBOiB2aWEgaWRCQTogQ09OIEM6ZXh0SW50cm9JZEJcbiAgQUEgLT4-IEE6IEM6aWRBQiBDT04gQzppZEFNXG4iLCJtZXJtYWlkIjp7fSwidXBkYXRlRWRpdG9yIjpmYWxzZX0)

rfcs/rejected/groups.mmd

@@ -0,0 +1,135 @@
+sequenceDiagram
+  participant M as Existing<br>member (M)
+  participant MA as Existing<br>member<br>agent (MA)
+  participant A as Alice (A)
+  participant AA as Alice's<br>agent (AA)
+  participant BA as Bob's<br>agent (BA)
+  participant B as Bob (B)
+
+  note over A, AA: 1. create new group (no members)
+  A ->> AA: G:gidA? NEW<br>(gidA - group ID of this group for A,<br>can be generated by the agent)
+
+  note over AA: create "internal" broadcast associated with the group<br>(B: NEW)
+
+  AA ->> A: G:gidA OK
+
+  note over A, BA: 2. add Bob to group
+
+  A ->> AA: C:idAB INTRO G:gidA gInfo<br>(idAB - conn alias A has for B)
+  
+  note over AA: generate new random ID for member B (midB, unique per group)<br>initiate "internal" connection gidAB for B in group<br>(internal means that it is not visible to the clients<br>and cannot be used with client commands)
+
+  AA ->> BA: via idAB: GROUP C:midB g:gInvAB gInfo
+  BA ->> B: C:idBA REQ G:invID gInfo<br>(invID - to refer to it in ACPT)
+  B ->> BA: G:gidB? ACPT G:invID<br>(RJCT G:invID could be added)
+
+  note over BA: create group and "internal" broadcast associated with the group<br>(B: NEW)
+
+  BA ->> B: G:gidB OK
+
+  BA ->> AA: establish internal connection gidBA (using g:gInvAB) for A in group
+
+  note over BA, AA: add connections gidBA and gidAB to broadcasts<br>(B: ADD)
+ 
+  AA ->> A: G:gidA CON C:idAB
+  BA ->> B: G:gidA CON C:idBA
+
+  note over M, B: For each existing member M:<br>create and accept internal introduction between connections, related to the group, via gidAB/BA/AM/MA, connections created are gidBM and gidMB<br>The fact that the introduction arrives via connection allocated for the group, allows agents identify it as a new group member, ID used in introductions is group-scoped member ID.
+
+  note over A, BA: once all members were sent to B
+  AA ->> BA: via gidAB: MEM C:midB
+
+  note over BA, B: once all members are connected
+  BA ->> B: G:gidB MEM
+
+  note over A, AA: once all members reported connection
+  AA ->> A: G:gidA MEM C:idAB
+
+  note over M, AA: for each member M
+
+  AA ->> MA: via gidAM: MEM C:midB
+  MA ->> M: G:gidM MEM C:idMB
+  
+  note over M, B: 3. B sends message to the group
+
+  B ->> BA: G:gidB SEND msg
+
+  note over BA: send message via associated broadcast and respond to client with SENT notifications
+
+  BA ->> B: G:gidB SENT C:idBA intMsgID
+  BA ->> B: G:gidB SENT C:idBM intMsgID
+  
+  note over BA, B: once sent to all
+  BA ->> B: G:gidB SENT intMsgID
+
+  AA ->> A: G:gidA MSG C:idAB intMsgID msgdata
+  A ->> AA: G:gidA ACK intMsgID
+  AA ->> BA: via gidAB: RCVD extMsgID hash sig
+  BA ->> B: G:gidA RCVD C:idBA intMsgID status<br>(status - message integrity check)
+
+  MA ->> M: G:gidM MSG C:idMB intMsgID msgdata
+  M ->> MA: G:gidM ACK intMsgID
+  MA ->> BA: via gidMB: RCVD extMsgID hash sig
+  BA ->> B: G:gidM RCVD C:idBM intMsgID status
+
+  note over BA, B: once received by all
+  BA ->> B: G:gidM RCVD intMsgID status
+
+  note over M, B: 4a. A leaves group
+
+  A ->> AA: G:gidA LEAVE
+  AA ->> A: G:gidA OK
+  AA ->> BA: via gidAB: LEFT
+  note over AA: remove gidAB, remove from broadcast
+  note over BA: remove gidBA, remove from broadcast
+  BA ->> B: G:gidB LEFT C:idBA
+
+  AA ->> MA: via gidAM: LEFT
+  note over AA: remove gidAM, remove from broadcast
+  note over MA: remove gidMA, remove from broadcast
+  MA ->> M: G:gidM LEFT C:idMA
+
+  AA ->> A: G:gidA LEFT
+
+  note over B, BA: if all members left
+  BA ->> B: G:gidB: EMPTY
+
+  note over M, B: 4b. A removes B from group
+
+  A ->> AA: G:gidA REM C:idAB
+  AA ->> A: G:gidA OK
+  AA ->> BA: via gidAB: OUT
+  note over BA: remove gidBA, all gidBM
+  BA ->> B: G:gidB OUT C:idBA
+
+  note over AA: remove gidAB
+  AA ->> A: G:gidA OK
+
+  note over M, B: below steps happen for each existing member M
+
+  AA ->> MA: via gidAM: REM C:midB
+  note over MA: remove gidMB
+  MA ->> AA: via gidMA: REMD C:midB
+  MA ->> M: G:gidM REMD C:idMB C:idMA<br>(B removed by A)
+
+  note over A, AA: once all members removed B
+
+  AA ->> A: G:gidA REMD C:idAB<br>(B removed by this agent)
+
+  note over M, B: 4c. A deletes group
+  A ->> AA: G:gidA DEL
+  AA ->> A: G:gidA OK
+  
+  AA ->> BA: via gidAB: DEL
+  note over BA: remove all group connections and messages
+  BA ->> B: G:gidB DELD C:idBA<br>(group deleted by A)
+  BA ->> AA: via gidBA: DELD
+  AA ->> A: G:gidA DELD C:idAB
+
+  AA ->> MA: via gidAM: DEL
+  note over MA: remove all group connections and messages
+  MA ->> M: G:gidM DELD C:idMA<br>(group deleted by A)
+  MA ->> AA: via gidMA: DELD
+  AA ->> A: G:gidA DELD C:idAM
+
+  AA ->> A: G:gidA DELD<br>(group deleted by this agent - all confirmed)

rfcs/rejected/intro.mmd

@@ -0,0 +1,42 @@
+sequenceDiagram
+  participant A as Alice (A) - the introducer
+  participant AA as Alice's<br>agent (AA)
+  participant B as Bob (B) - introduced
+  participant BA as Bob's<br>agent (BA)
+  participant M as Mark (M) - introduced to
+  participant MA as Mark's<br>agent (MA)
+
+  note over A, AA: 1. create introduction
+  A ->> AA: C:idAB INTRO C:idAM infoM<br>(idAB - conn alias A has for B,<br>idAM - for M)
+  AA ->> A: C:idAB OK
+
+  note over A, BA: 2. send intro to Bob
+
+  AA ->> BA: via idAB: INTRO C:extIntroIdM infoM
+  BA ->> B: C:idBA REQ C:intIntroIdM infoM
+  B ->> BA: C:idBM? ACPT C:intIntroIdM
+  BA ->> B: C:idBM OK
+
+  note over BA: 3. create connection for  M idBM
+
+  BA ->> AA: via idBA: INV C:extIntroIdM invBM infoB
+
+  note over AA, M: 4. send intro to Mark
+
+  AA ->> MA: via idAM: REQ C:extIntroIdB invBM infoB
+
+  note over MA, B: 5. Mark connects to Bob
+
+  MA ->> M: C:idMA REQ C:intIntroIdB infoB
+  M ->> MA: C:idMB? ACPT C:intIntroIdB
+  MA ->> M: C:idMB OK
+
+  MA ->> BA:  establish connection idBM -> idMB
+
+  note over A, MA: 6. notify all clients
+
+  MA ->> M: C:idMB CON
+  MA ->> AA: via idMA: CON C:extIntroIdB
+  BA ->> B: C:idBM CON
+  BA ->> AA: via idBA: CON C:extIntroIdB
+  AA ->> A: C:idAB CON C:idAM

scripts/smp-server-digitalocean-droplet/README.md

@@ -0,0 +1,23 @@
+# SMP server image for DigitalOcean
+
+## How to build an image
+
+1. [Create an API token](https://cloud.digitalocean.com/account/api/tokens) in vendor account in DigitalOcean.
+2. Install [packer](https://www.packer.io/downloads) downloading binary or with brew (on Mac):
+
+```shell
+brew tap hashicorp/tap
+brew install hashicorp/tap/packer
+```
+
+3. Run `packer build` in the `smp-server-digitalocean-droplet` repository:
+
+```shell
+cd ./scripts/smp-server-digitalocean-droplet
+DIGITALOCEAN_TOKEN=$YOUR_TOKEN packer build -on-error=ask -color=false ./marketplace-image.json
+```
+
+**TODO** (see Linode script)
+
+- Increase file descriptors limit
+- Configure Restart for systemd service

scripts/smp-server-digitalocean-droplet/files/opt/simplex/initialize_server.sh

@@ -0,0 +1,51 @@
+#!/bin/bash
+
+# Download latest release
+bin_dir="/opt/simplex/bin"
+binary="$bin_dir/smp-server"
+mkdir -p $bin_dir
+curl -L -o $binary https://github.com/simplex-chat/simplexmq/releases/latest/download/smp-server-ubuntu-20_04-x86-64
+chmod +x $binary
+
+# / Add to PATH
+cat > /etc/profile.d/simplex.sh << EOF
+#!/bin/bash
+
+export PATH="$PATH:$bin_dir"
+
+EOF
+# Add to PATH /
+
+# Source and test PATH
+source /etc/profile.d/simplex.sh
+smp-server --version
+
+# Initialize server
+ip_address=$(curl ifconfig.me)
+smp-server init -l --ip $ip_address
+
+# Server fingerprint
+fingerprint=$(cat /etc/opt/simplex/fingerprint)
+
+# Set up welcome script
+echo "bash /opt/simplex/on_login.sh $fingerprint $ip_address" >> /root/.bashrc
+
+# / Create systemd service for SMP server
+cat > /etc/systemd/system/smp-server.service << EOF
+[Unit]
+Description=SMP server
+
+[Service]
+Type=simple
+ExecStart=/bin/sh -c "exec $binary start >> /var/opt/simplex/smp-server.log 2>&1"
+
+[Install]
+WantedBy=multi-user.target
+
+EOF
+# Create systemd service for SMP server /
+
+# Start systemd service for SMP server
+chmod 644 /etc/systemd/system/smp-server.service
+sudo systemctl enable smp-server
+sudo systemctl start smp-server

scripts/smp-server-digitalocean-droplet/files/opt/simplex/on_login.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+fingerprint=$1
+server_address=$2
+
+cat <<EOF
+********************************************************************************
+
+SMP server address: smp://$fingerprint@$server_address
+Check SMP server status with: systemctl status smp-server
+
+To keep this server secure, the UFW firewall is enabled.
+All ports are BLOCKED except 22 (SSH), 443 (HTTPS), 5223 (SMP server).
+
+********************************************************************************
+To stop seeing this message delete line - bash /opt/simplex/on_login.sh - from /root/.bashrc
+EOF

scripts/smp-server-digitalocean-droplet/files/opt/simplex/server_bootstrap.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -eu
+
+if [[ ! -f /opt/simplex/do_initialize_server ]]; then
+  touch /opt/simplex/do_initialize_server
+elif [[ ! -f /etc/opt/simplex/smp-server.ini ]]; then
+  chmod +x /opt/simplex/initialize_server.sh
+  /opt/simplex/initialize_server.sh
+else
+  echo "SMP server already initialized"
+fi

scripts/smp-server-digitalocean-droplet/marketplace-image.json

@@ -0,0 +1,47 @@
+{
+  "variables": {
+    "token": "{{env `DIGITALOCEAN_TOKEN`}}",
+    "image_name": "smp-server-snapshot",
+    "application_name": "SMP server"
+  },
+  "sensitive-variables": ["token"],
+  "builders": [
+    {
+      "type": "digitalocean",
+      "api_token": "{{user `token`}}",
+      "image": "ubuntu-20-04-x64",
+      "region": "fra1",
+      "size": "s-1vcpu-1gb",
+      "ssh_username": "root",
+      "snapshot_name": "{{user `image_name`}}"
+    }
+  ],
+  "provisioners": [
+    {
+      "type": "shell",
+      "inline": [
+        "cloud-init status --wait",
+        "mkdir -p /opt/simplex"
+      ]
+    },
+    {
+      "type": "file",
+      "source": "files/opt/",
+      "destination": "/opt/"
+    },
+    {
+      "type": "shell",
+      "environment_vars": [
+        "application_name={{user `application_name`}}",
+        "DEBIAN_FRONTEND=noninteractive"
+      ],
+      "scripts": [
+        "scripts/01-packages.sh",
+        "scripts/02-firewall.sh",
+        "scripts/03-init-start.sh",
+        "scripts/90-cleanup.sh",
+        "scripts/99-img-check.sh"
+      ]
+    }
+  ]
+}

scripts/smp-server-digitalocean-droplet/scripts/01-packages.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+# https://superuser.com/questions/1638779/automatic-yess-to-linux-update-upgrade
+# https://superuser.com/questions/1412054/non-interactive-apt-upgrade
+sudo DEBIAN_FRONTEND=noninteractive \
+  apt-get \
+  -o Dpkg::Options::=--force-confold \
+  -o Dpkg::Options::=--force-confdef \
+  -y --allow-downgrades --allow-remove-essential --allow-change-held-packages \
+  update
+
+sudo DEBIAN_FRONTEND=noninteractive \
+  apt-get \
+  -o Dpkg::Options::=--force-confold \
+  -o Dpkg::Options::=--force-confdef \
+  -y --allow-downgrades --allow-remove-essential --allow-change-held-packages \
+  dist-upgrade
+
+# TODO install unattended-upgrades; jq is not needed on DigitalOcean
+# sudo DEBIAN_FRONTEND=noninteractive \
+#   apt-get \
+#   -o Dpkg::Options::=--force-confold \
+#   -o Dpkg::Options::=--force-confdef \
+#   -y --allow-downgrades --allow-remove-essential --allow-change-held-packages \
+#   install jq

scripts/smp-server-digitalocean-droplet/scripts/02-firewall.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+# Add firewall
+echo "y" | ufw enable
+
+# Open ports
+ufw allow ssh
+ufw allow https
+ufw allow 5223

scripts/smp-server-digitalocean-droplet/scripts/03-init-start.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+chmod +x /opt/simplex/server_bootstrap.sh
+
+# / Create systemd service for server bootstrap script
+cat > /etc/systemd/system/server-bootstrap.service << EOF
+[Unit]
+Description=Server bootstrap script that downloads and initializes SMP server from the latest release
+
+[Service]
+Type=oneshot
+ExecStart=/opt/simplex/server_bootstrap.sh
+
+[Install]
+WantedBy=multi-user.target
+
+EOF
+# Create systemd service for server bootstrap script /
+
+# Start systemd service for server bootstrap script
+chmod 644 /etc/systemd/system/server-bootstrap.service
+sudo systemctl enable server-bootstrap
+sudo systemctl start server-bootstrap

scripts/smp-server-digitalocean-droplet/scripts/90-cleanup.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# DigitalOcean Marketplace Image Validation Tool
+# © 2021 DigitalOcean LLC.
+# This code is licensed under Apache 2.0 license (see LICENSE.md for details)
+
+set -o errexit
+
+# Ensure /tmp exists and has the proper permissions before
+# checking for security updates
+# https://github.com/digitalocean/marketplace-partners/issues/94
+if [[ ! -d /tmp ]]; then
+  mkdir /tmp
+fi
+chmod 1777 /tmp
+
+if [ -n "$(command -v yum)" ]; then
+  yum update -y
+  yum clean all
+elif [ -n "$(command -v apt-get)" ]; then
+  apt-get -y update
+  apt-get -y upgrade
+  apt-get -y autoremove
+  apt-get -y autoclean
+fi
+
+rm -rf /tmp/* /var/tmp/*
+history -c
+cat /dev/null > /root/.bash_history
+unset HISTFILE
+find /var/log -mtime -1 -type f -exec truncate -s 0 {} \;
+rm -rf /var/log/*.gz /var/log/*.[0-9] /var/log/*-????????
+rm -rf /var/lib/cloud/instances/*
+rm -f /root/.ssh/authorized_keys /etc/ssh/*key*
+touch /etc/ssh/revoked_keys
+chmod 600 /etc/ssh/revoked_keys
+
+# Securely erase the unused portion of the filesystem
+GREEN='\033[0;32m'
+NC='\033[0m'
+printf "\n${GREEN}Writing zeros to the remaining disk space to securely
+erase the unused portion of the file system.
+Depending on your disk size this may take several minutes.
+The secure erase will complete successfully when you see:${NC}
+    dd: writing to '/zerofile': No space left on device\n
+Beginning secure erase now\n"
+
+dd if=/dev/zero of=/zerofile &
+  PID=$!
+  while [ -d /proc/$PID ]
+    do
+      printf "."
+      sleep 5
+    done
+sync; rm /zerofile; sync
+cat /dev/null > /var/log/lastlog; cat /dev/null > /var/log/wtmp
+
+rm /var/log/auth.log
+rm /var/log/kern.log
+rm /var/log/ufw.log

scripts/smp-server-digitalocean-droplet/scripts/99-img-check.sh

@@ -0,0 +1,682 @@
+#!/bin/bash
+
+# DigitalOcean Marketplace Image Validation Tool
+# © 2021 DigitalOcean LLC.
+# This code is licensed under Apache 2.0 license (see LICENSE.md for details)
+
+VERSION="v. 1.6"
+RUNDATE=$( date )
+
+# Script should be run with SUDO
+if [ "$EUID" -ne 0 ]
+  then echo "[Error] - This script must be run with sudo or as the root user."
+  exit 1
+fi
+
+STATUS=0
+PASS=0
+WARN=0
+FAIL=0
+
+# $1 == command to check for
+# returns: 0 == true, 1 == false
+cmdExists() {
+    if command -v "$1" > /dev/null 2>&1; then
+        return 0
+    else
+        return 1
+    fi
+}
+
+function getDistro {
+    if [ -f /etc/os-release ]; then
+    # freedesktop.org and systemd
+    . /etc/os-release
+    OS=$NAME
+    VER=$VERSION_ID
+elif type lsb_release >/dev/null 2>&1; then
+    # linuxbase.org
+    OS=$(lsb_release -si)
+    VER=$(lsb_release -sr)
+elif [ -f /etc/lsb-release ]; then
+    # For some versions of Debian/Ubuntu without lsb_release command
+    . /etc/lsb-release
+    OS=$DISTRIB_ID
+    VER=$DISTRIB_RELEASE
+elif [ -f /etc/debian_version ]; then
+    # Older Debian/Ubuntu/etc.
+    OS=Debian
+    VER=$(cat /etc/debian_version)
+elif [ -f /etc/SuSe-release ]; then
+    # Older SuSE/etc.
+    :
+elif [ -f /etc/redhat-release ]; then
+    # Older Red Hat, CentOS, etc.
+    VER=$( cat /etc/redhat-release | cut -d" " -f3 | cut -d "." -f1)
+    d=$( cat /etc/redhat-release | cut -d" " -f1 | cut -d "." -f1)
+    if [[ $d == "CentOS" ]]; then
+      OS="CentOS Linux"
+    fi
+else
+    # Fall back to uname, e.g. "Linux <version>", also works for BSD, etc.
+    OS=$(uname -s)
+    VER=$(uname -r)
+fi
+}
+function loadPasswords {
+SHADOW=$(cat /etc/shadow)
+}
+
+function checkAgent {
+  # Check for the presence of the do-agent in the filesystem
+  if [ -d /var/opt/digitalocean/do-agent ];then
+     echo -en "\e[41m[FAIL]\e[0m DigitalOcean Monitoring Agent detected.\n"
+            ((FAIL++))
+            STATUS=2
+      if [[ $OS == "CentOS Linux" ]]; then
+        echo "The agent can be removed with 'sudo yum remove do-agent' "
+      elif [[ $OS == "Ubuntu" ]]; then
+        echo "The agent can be removed with 'sudo apt-get purge do-agent' "
+      fi
+  else
+    echo -en "\e[32m[PASS]\e[0m DigitalOcean Monitoring agent was not found\n"
+    ((PASS++))
+  fi
+}
+
+function checkLogs {
+    cp_ignore="/var/log/cpanel-install.log"
+    echo -en "\nChecking for log files in /var/log\n\n"
+    # Check if there are log archives or log files that have not been recently cleared.
+    for f in /var/log/*-????????; do
+      [[ -e $f ]] || break
+      if [ $f != $cp_ignore ]; then
+        echo -en "\e[93m[WARN]\e[0m Log archive ${f} found\n"
+        ((WARN++))
+        if [[ $STATUS != 2 ]]; then
+            STATUS=1
+        fi
+      fi
+    done
+    for f in  /var/log/*.[0-9];do
+      [[ -e $f ]] || break
+        echo -en "\e[93m[WARN]\e[0m Log archive ${f} found\n"
+        ((WARN++))
+        if [[ $STATUS != 2 ]]; then
+            STATUS=1
+        fi
+    done
+    for f in /var/log/*.log; do
+      [[ -e $f ]] || break
+      if [[ "${f}" = '/var/log/lfd.log' && "$( cat "${f}" | egrep -v '/var/log/messages has been reset| Watching /var/log/messages' | wc -c)" -gt 50 ]]; then
+        if [ $f != $cp_ignore ]; then
+        echo -en "\e[93m[WARN]\e[0m un-cleared log file, ${f} found\n"
+        ((WARN++))
+        if [[ $STATUS != 2 ]]; then
+            STATUS=1
+        fi
+      fi
+      elif [[ "${f}" != '/var/log/lfd.log' && "$( cat "${f}" | wc -c)" -gt 50 ]]; then
+      if [ $f != $cp_ignore ]; then
+        echo -en "\e[93m[WARN]\e[0m un-cleared log file, ${f} found\n"
+        ((WARN++))
+        if [[ $STATUS != 2 ]]; then
+            STATUS=1
+        fi
+      fi
+    fi
+    done
+}
+function checkTMP {
+  # Check the /tmp directory to ensure it is empty.  Warn on any files found.
+  return 1
+}
+function checkRoot {
+    user="root"
+    uhome="/root"
+    for usr in $SHADOW
+    do
+      IFS=':' read -r -a u <<< "$usr"
+      if [[ "${u[0]}" == "${user}" ]]; then
+        if [[ ${u[1]} == "!" ]] || [[ ${u[1]} == "!!" ]] || [[ ${u[1]} == "*" ]]; then
+            echo -en "\e[32m[PASS]\e[0m User ${user} has no password set.\n"
+            ((PASS++))
+        else
+            echo -en "\e[41m[FAIL]\e[0m User ${user} has a password set on their account.\n"
+            ((FAIL++))
+            STATUS=2
+        fi
+      fi
+    done
+    if [ -d ${uhome}/ ]; then
+            if [ -d ${uhome}/.ssh/ ]; then
+                if  ls ${uhome}/.ssh/*> /dev/null 2>&1; then
+                    for key in ${uhome}/.ssh/*
+                        do
+                             if  [ "${key}" == "${uhome}/.ssh/authorized_keys" ]; then
+
+                                if [ "$( cat "${key}" | wc -c)" -gt 50 ]; then
+                                    echo -en "\e[41m[FAIL]\e[0m User \e[1m${user}\e[0m has a populated authorized_keys file in \e[93m${key}\e[0m\n"
+                                    akey=$(cat ${key})
+                                    echo "File Contents:"
+                                    echo $akey
+                                    echo "--------------"
+                                    ((FAIL++))
+                                    STATUS=2
+                                fi
+                            elif  [ "${key}" == "${uhome}/.ssh/id_rsa" ]; then
+                                if [ "$( cat "${key}" | wc -c)" -gt 0 ]; then
+                                  echo -en "\e[41m[FAIL]\e[0m User \e[1m${user}\e[0m has a private key file in \e[93m${key}\e[0m\n"
+                                      akey=$(cat ${key})
+                                      echo "File Contents:"
+                                      echo $akey
+                                      echo "--------------"
+                                      ((FAIL++))
+                                      STATUS=2
+                                else
+                                  echo -en "\e[93m[WARN]\e[0m User \e[1m${user}\e[0m has empty private key file in \e[93m${key}\e[0m\n"
+                                  ((WARN++))
+                                  if [[ $STATUS != 2 ]]; then
+                                    STATUS=1
+                                  fi
+                                fi
+                            elif  [ "${key}" != "${uhome}/.ssh/known_hosts" ]; then
+                                 echo -en "\e[93m[WARN]\e[0m User \e[1m${user}\e[0m has a file in their .ssh directory at \e[93m${key}\e[0m\n"
+                                    ((WARN++))
+                                    if [[ $STATUS != 2 ]]; then
+                                        STATUS=1
+                                    fi
+                            else
+                                if [ "$( cat "${key}" | wc -c)" -gt 50 ]; then
+                                    echo -en "\e[93m[WARN]\e[0m User \e[1m${user}\e[0m has a populated known_hosts file in \e[93m${key}\e[0m\n"
+                                    ((WARN++))
+                                    if [[ $STATUS != 2 ]]; then
+                                        STATUS=1
+                                    fi
+                                fi
+                            fi
+                        done
+                else
+                    echo -en "\e[32m[ OK ]\e[0m User \e[1m${user}\e[0m has no SSH keys present\n"
+                fi
+            else
+                echo -en "\e[32m[ OK ]\e[0m User \e[1m${user}\e[0m does not have an .ssh directory\n"
+            fi
+             if [ -f /root/.bash_history ];then
+
+                      BH_S=$( cat /root/.bash_history | wc -c)
+
+                      if [[ $BH_S -lt 200 ]]; then
+                          echo -en "\e[32m[PASS]\e[0m ${user}'s Bash History appears to have been cleared\n"
+                          ((PASS++))
+                      else
+                          echo -en "\e[41m[FAIL]\e[0m ${user}'s Bash History should be cleared to prevent sensitive information from leaking\n"
+                          ((FAIL++))
+                              STATUS=2
+                      fi
+
+                      return 1;
+                  else
+                      echo -en "\e[32m[PASS]\e[0m The Root User's Bash History is not present\n"
+                      ((PASS++))
+                  fi
+        else
+            echo -en "\e[32m[ OK ]\e[0m User \e[1m${user}\e[0m does not have a directory in /home\n"
+        fi
+        echo -en "\n\n"
+    return 1
+}
+
+function checkUsers {
+    # Check each user-created account
+    for user in $(awk -F: '$3 >= 1000 && $1 != "nobody" {print $1}' /etc/passwd;)
+    do
+      # Skip some other non-user system accounts
+      if [[ $user == "centos" ]]; then
+        :
+      elif [[ $user == "nfsnobody" ]]; then
+        :
+    else
+      echo -en "\nChecking user: ${user}...\n"
+      for usr in $SHADOW
+        do
+          IFS=':' read -r -a u <<< "$usr"
+          if [[ "${u[0]}" == "${user}" ]]; then
+              if [[ ${u[1]} == "!" ]] || [[ ${u[1]} == "!!" ]] || [[ ${u[1]} == "*" ]]; then
+                  echo -en "\e[32m[PASS]\e[0m User ${user} has no password set.\n"
+                  ((PASS++))
+              else
+                  echo -en "\e[41m[FAIL]\e[0m User ${user} has a password set on their account. Only system users are allowed on the image.\n"
+                  ((FAIL++))
+                  STATUS=2
+              fi
+          fi
+        done
+        #echo "User Found: ${user}"
+        uhome="/home/${user}"
+        if [ -d "${uhome}/" ]; then
+            if [ -d "${uhome}/.ssh/" ]; then
+                if  ls "${uhome}/.ssh/*"> /dev/null 2>&1; then
+                    for key in ${uhome}/.ssh/*
+                        do
+                            if  [ "${key}" == "${uhome}/.ssh/authorized_keys" ]; then
+                                if [ "$( cat "${key}" | wc -c)" -gt 50 ]; then
+                                    echo -en "\e[41m[FAIL]\e[0m User \e[1m${user}\e[0m has a populated authorized_keys file in \e[93m${key}\e[0m\n"
+                                    akey=$(cat ${key})
+                                    echo "File Contents:"
+                                    echo $akey
+                                    echo "--------------"
+                                    ((FAIL++))
+                                    STATUS=2
+                                fi
+                              elif  [ "${key}" == "${uhome}/.ssh/id_rsa" ]; then
+                                if [ "$( cat "${key}" | wc -c)" -gt 0 ]; then
+                                  echo -en "\e[41m[FAIL]\e[0m User \e[1m${user}\e[0m has a private key file in \e[93m${key}\e[0m\n"
+                                      akey=$(cat ${key})
+                                      echo "File Contents:"
+                                      echo $akey
+                                      echo "--------------"
+                                      ((FAIL++))
+                                      STATUS=2
+                                else
+                                  echo -en "\e[93m[WARN]\e[0m User \e[1m${user}\e[0m has empty private key file in \e[93m${key}\e[0m\n"
+                                  ((WARN++))
+                                  if [[ $STATUS != 2 ]]; then
+                                    STATUS=1
+                                  fi
+                                fi
+                            elif  [ "${key}" != "${uhome}/.ssh/known_hosts" ]; then
+
+                                 echo -en "\e[93m[WARN]\e[0m User \e[1m${user}\e[0m has a file in their .ssh directory named \e[93m${key}\e[0m\n"
+                                 ((WARN++))
+                                 if [[ $STATUS != 2 ]]; then
+                                        STATUS=1
+                                    fi
+
+                            else
+                                if [ "$( cat "${key}" | wc -c)" -gt 50 ]; then
+                                    echo -en "\e[93m[WARN]\e[0m User \e[1m${user}\e[0m has a known_hosts file in \e[93m${key}\e[0m\n"
+                                    ((WARN++))
+                                    if [[ $STATUS != 2 ]]; then
+                                        STATUS=1
+                                    fi
+                                fi
+                            fi
+
+
+                        done
+                else
+                    echo -en "\e[32m[ OK ]\e[0m User \e[1m${user}\e[0m has no SSH keys present\n"
+                fi
+            else
+                echo -en "\e[32m[ OK ]\e[0m User \e[1m${user}\e[0m does not have an .ssh directory\n"
+            fi
+        else
+            echo -en "\e[32m[ OK ]\e[0m User \e[1m${user}\e[0m does not have a directory in /home\n"
+        fi
+
+         # Check for an uncleared .bash_history for this user
+              if [ -f "${uhome}/.bash_history" ]; then
+                            BH_S=$( cat "${uhome}/.bash_history" | wc -c )
+
+                            if [[ $BH_S -lt 200 ]]; then
+                                echo -en "\e[32m[PASS]\e[0m ${user}'s Bash History appears to have been cleared\n"
+                                ((PASS++))
+                            else
+                                echo -en "\e[41m[FAIL]\e[0m ${user}'s Bash History should be cleared to prevent sensitive information from leaking\n"
+                                ((FAIL++))
+                                    STATUS=2
+
+                            fi
+                           echo -en "\n\n"
+                         fi
+        fi
+    done
+}
+function checkFirewall {
+
+    if [[ $OS == "Ubuntu" ]]; then
+      fw="ufw"
+      ufwa=$(ufw status |head -1| sed -e "s/^Status:\ //")
+      if [[ $ufwa == "active" ]]; then
+        FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+        ((PASS++))
+      else
+        FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+        ((WARN++))
+      fi
+    elif [[ $OS == "CentOS Linux" ]]; then
+      if [ -f /usr/lib/systemd/system/csf.service ]; then
+        fw="csf"
+        if [[ $(systemctl status $fw >/dev/null 2>&1) ]]; then
+
+        FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+        ((PASS++))
+        elif cmdExists "firewall-cmd"; then
+          if [[ $(systemctl is-active firewalld >/dev/null 2>&1 && echo 1 || echo 0) ]]; then
+           FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+          ((PASS++))
+          else
+            FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+          ((WARN++))
+          fi
+        else
+          FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+        ((WARN++))
+        fi
+      else
+        fw="firewalld"
+        if [[ $(systemctl is-active firewalld >/dev/null 2>&1 && echo 1 || echo 0) ]]; then
+          FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+        ((PASS++))
+        else
+          FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+        ((WARN++))
+        fi
+      fi
+    elif [[ "$OS" =~ Debian.* ]]; then
+      # user could be using a number of different services for managing their firewall
+      # we will check some of the most common
+      if cmdExists 'ufw'; then
+        fw="ufw"
+        ufwa=$(ufw status |head -1| sed -e "s/^Status:\ //")
+        if [[ $ufwa == "active" ]]; then
+        FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+        ((PASS++))
+      else
+        FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+        ((WARN++))
+      fi
+      elif cmdExists "firewall-cmd"; then
+        fw="firewalld"
+        if [[ $(systemctl is-active --quiet $fw) ]]; then
+          FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+        ((PASS++))
+        else
+          FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+        ((WARN++))
+        fi
+      else
+        # user could be using vanilla iptables, check if kernel module is loaded
+        fw="iptables"
+        if [[ $(lsmod | grep -q '^ip_tables' 2>/dev/null) ]]; then
+          FW_VER="\e[32m[PASS]\e[0m Firewall service (${fw}) is active\n"
+        ((PASS++))
+        else
+          FW_VER="\e[93m[WARN]\e[0m No firewall is configured. Ensure ${fw} is installed and configured\n"
+        ((WARN++))
+        fi
+      fi
+    fi
+
+}
+function checkUpdates {
+    if [[ $OS == "Ubuntu" ]] || [[ "$OS" =~ Debian.* ]]; then
+        # Ensure /tmp exists and has the proper permissions before
+        # checking for security updates
+        # https://github.com/digitalocean/marketplace-partners/issues/94
+        if [[ ! -d /tmp ]]; then
+          mkdir /tmp
+        fi
+        chmod 1777 /tmp
+
+        echo -en "\nUpdating apt package database to check for security updates, this may take a minute...\n\n"
+        apt-get -y update > /dev/null
+
+        uc=$(apt-get --just-print upgrade | grep -i "security" | wc -l)
+        if [[ $uc -gt 0 ]]; then
+          update_count=$(( ${uc} / 2 ))
+        else
+          update_count=0
+        fi
+
+        if [[ $update_count -gt 0 ]]; then
+            echo -en "\e[41m[FAIL]\e[0m There are ${update_count} security updates available for this image that have not been installed.\n"
+            echo -en
+            echo -en "Here is a list of the security updates that are not installed:\n"
+            sleep 2
+            apt-get --just-print upgrade | grep -i security | awk '{print $2}' | awk '!seen[$0]++'
+            echo -en
+            ((FAIL++))
+            STATUS=2
+        else
+            echo -en "\e[32m[PASS]\e[0m There are no pending security updates for this image.\n\n"
+        fi
+    elif [[ $OS == "CentOS Linux" ]]; then
+        echo -en "\nChecking for available security updates, this may take a minute...\n\n"
+
+        update_count=$(yum check-update --security --quiet | wc -l)
+         if [[ $update_count -gt 0 ]]; then
+            echo -en "\e[41m[FAIL]\e[0m There are ${update_count} security updates available for this image that have not been installed.\n"
+            ((FAIL++))
+            STATUS=2
+        else
+            echo -en "\e[32m[PASS]\e[0m There are no pending security updates for this image.\n"
+            ((PASS++))
+        fi
+    else
+        echo "Error encountered"
+        exit 1
+    fi
+
+    return 1;
+}
+function checkCloudInit {
+
+    if hash cloud-init 2>/dev/null; then
+        CI="\e[32m[PASS]\e[0m Cloud-init is installed.\n"
+        ((PASS++))
+    else
+        CI="\e[41m[FAIL]\e[0m No valid verison of cloud-init was found.\n"
+        ((FAIL++))
+        STATUS=2
+    fi
+    return 1
+}
+function checkMongoDB {
+  # Check if MongoDB is installed
+  # If it is, verify the version is allowed (non-SSPL)
+
+   if [[ $OS == "Ubuntu" ]] || [[ "$OS" =~ Debian.* ]]; then
+
+     if [[ -f "/usr/bin/mongod" ]]; then
+       version=$(/usr/bin/mongod --version --quiet | grep "db version" | sed -e "s/^db\ version\ v//")
+
+      if version_gt $version 4.0.0; then
+        if version_gt $version 4.0.3; then
+          echo -en "\e[41m[FAIL]\e[0m An SSPL version of MongoDB is present, ${version}"
+          ((FAIL++))
+           STATUS=2
+        else
+          echo -en "\e[32m[PASS]\e[0m The version of MongoDB installed, ${version} is not under the SSPL"
+          ((PASS++))
+        fi
+      else
+         if version_gt $version 3.6.8; then
+          echo -en "\e[41m[FAIL]\e[0m An SSPL version of MongoDB is present, ${version}"
+          ((FAIL++))
+           STATUS=2
+        else
+          echo -en "\e[32m[PASS]\e[0m The version of MongoDB installed, ${version} is not under the SSPL"
+          ((PASS++))
+        fi
+      fi
+
+
+     else
+       echo -en "\e[32m[PASS]\e[0m MongoDB is not installed"
+       ((PASS++))
+     fi
+
+   elif [[ $OS == "CentOS Linux" ]]; then
+
+    if [[ -f "/usr/bin/mongod" ]]; then
+       version=$(/usr/bin/mongod --version --quiet | grep "db version" | sed -e "s/^db\ version\ v//")
+
+
+       if version_gt $version 4.0.0; then
+        if version_gt $version 4.0.3; then
+          echo -en "\e[41m[FAIL]\e[0m An SSPL version of MongoDB is present"
+          ((FAIL++))
+           STATUS=2
+        else
+          echo -en "\e[32m[PASS]\e[0m The version of MongoDB installed is not under the SSPL"
+          ((PASS++))
+        fi
+      else
+         if version_gt $version 3.6.8; then
+          echo -en "\e[41m[FAIL]\e[0m An SSPL version of MongoDB is present"
+          ((FAIL++))
+           STATUS=2
+        else
+          echo -en "\e[32m[PASS]\e[0m The version of MongoDB installed is not under the SSPL"
+          ((PASS++))
+        fi
+      fi
+
+
+
+     else
+       echo -en "\e[32m[PASS]\e[0m MongoDB is not installed"
+       ((PASS++))
+     fi
+
+  else
+    echo "ERROR: Unable to identify distribution"
+    ((FAIL++))
+    STATUS 2
+    return 1
+  fi
+
+
+}
+
+function version_gt() { test "$(printf '%s\n' "$@" | sort -V | head -n 1)" != "$1"; }
+
+
+clear
+echo "DigitalOcean Marketplace Image Validation Tool ${VERSION}"
+echo "Executed on: ${RUNDATE}"
+echo "Checking local system for Marketplace compatibility..."
+
+getDistro
+
+echo -en "\n\e[1mDistribution:\e[0m ${OS}\n"
+echo -en "\e[1mVersion:\e[0m ${VER}\n\n"
+
+ost=0
+osv=0
+
+if [[ $OS == "Ubuntu" ]]; then
+        ost=1
+    if [[ $VER == "20.04" ]]; then
+        osv=1
+    elif [[ $VER == "18.04" ]]; then
+        osv=1
+    elif [[ $VER == "16.04" ]]; then
+        osv=1
+    else
+        osv=0
+    fi
+
+elif [[ "$OS" =~ Debian.* ]]; then
+    ost=1
+    case "$VER" in
+        9)
+            osv=1
+            ;;
+        10)
+            osv=1
+            ;;
+        *)
+            osv=2
+            ;;
+    esac
+
+elif [[ $OS == "CentOS Linux" ]]; then
+        ost=1
+    if [[ $VER == "8" ]]; then
+        osv=1
+    elif [[ $VER == "7" ]]; then
+        osv=1
+    elif [[ $VER == "6" ]]; then
+        osv=1
+    else
+        osv=2
+    fi
+else
+    ost=0
+fi
+
+if [[ $ost == 1 ]]; then
+    echo -en "\e[32m[PASS]\e[0m Supported Operating System Detected: ${OS}\n"
+    ((PASS++))
+else
+    echo -en "\e[41m[FAIL]\e[0m ${OS} is not a supported Operating System\n"
+    ((FAIL++))
+    STATUS=2
+fi
+
+if [[ $osv == 1 ]]; then
+    echo -en "\e[32m[PASS]\e[0m Supported Release Detected: ${VER}\n"
+    ((PASS++))
+elif [[ $ost == 1 ]]; then
+    echo -en "\e[41m[FAIL]\e[0m ${OS} ${VER} is not a supported Operating System Version\n"
+    ((FAIL++))
+    STATUS=2
+else
+    echo "Exiting..."
+    exit 1
+fi
+
+checkCloudInit
+
+echo -en "${CI}"
+
+checkFirewall
+
+echo -en "${FW_VER}"
+
+checkUpdates
+
+loadPasswords
+
+checkLogs
+
+echo -en "\n\nChecking all user-created accounts...\n"
+checkUsers
+
+echo -en "\n\nChecking the root account...\n"
+checkRoot
+
+checkAgent
+
+checkMongoDB
+
+
+# Summary
+echo -en "\n\n---------------------------------------------------------------------------------------------------\n"
+
+if [[ $STATUS == 0 ]]; then
+    echo -en "Scan Complete.\n\e[32mAll Tests Passed!\e[0m\n"
+elif [[ $STATUS == 1 ]]; then
+    echo -en "Scan Complete. \n\e[93mSome non-critical tests failed.  Please review these items.\e[0m\e[0m\n"
+else
+    echo -en "Scan Complete. \n\e[41mOne or more tests failed.  Please review these items and re-test.\e[0m\n"
+fi
+echo "---------------------------------------------------------------------------------------------------"
+echo -en "\e[1m${PASS} Tests PASSED\e[0m\n"
+echo -en "\e[1m${WARN} WARNINGS\e[0m\n"
+echo -en "\e[1m${FAIL} Tests FAILED\e[0m\n"
+echo -en "---------------------------------------------------------------------------------------------------\n"
+
+if [[ $STATUS == 0 ]]; then
+    echo -en "We did not detect any issues with this image. Please be sure to manually ensure that all software installed on the base system is functional, secure and properly configured (or facilities for configuration on first-boot have been created).\n\n"
+    exit 0
+elif [[ $STATUS == 1 ]]; then
+    echo -en "Please review all [WARN] items above and ensure they are intended or resolved.  If you do not have a specific requirement, we recommend resolving these items before image submission\n\n"
+    exit 0
+else
+    echo -en "Some critical tests failed.  These items must be resolved and this scan re-run before you submit your image to the DigitalOcean Marketplace.\n\n"
+    exit 1
+fi

scripts/smp-server-linode.sh

@@ -0,0 +1,178 @@
+#!/bin/bash
+
+# <UDF name="enable_store_log" label="Store log - persist SMP queues to append only log and restore them upon server restart." default="on" oneof="on, off" />
+# <UDF name="api_token" label="Linode API token - enable Linode to create tags with server address, fingerprint and version. Note: minimal permissions token should have are read/write access to `linodes` (to create tags) and `domains` (to add A record for the third level domain if FQDN is provided)." default="" />
+# <UDF name="fqdn" label="FQDN (Fully Qualified Domain Name) - provide third level domain name (e.g. smp.example.com). If provided use `smp://fingerprint@FQDN` as server address in the client. If FQDN is not provided use `smp://fingerprint@IP` instead." default="" />
+
+# Log all stdout output to stackscript.log
+exec &> >(tee -i /var/log/stackscript.log)
+
+# Uncomment next line to enable debugging features
+# set -xeo pipefail
+
+cd $HOME
+
+# https://superuser.com/questions/1638779/automatic-yess-to-linux-update-upgrade
+# https://superuser.com/questions/1412054/non-interactive-apt-upgrade
+sudo DEBIAN_FRONTEND=noninteractive \
+  apt-get \
+  -o Dpkg::Options::=--force-confold \
+  -o Dpkg::Options::=--force-confdef \
+  -y --allow-downgrades --allow-remove-essential --allow-change-held-packages \
+  update
+
+sudo DEBIAN_FRONTEND=noninteractive \
+  apt-get \
+  -o Dpkg::Options::=--force-confold \
+  -o Dpkg::Options::=--force-confdef \
+  -y --allow-downgrades --allow-remove-essential --allow-change-held-packages \
+  dist-upgrade
+
+# TODO install unattended-upgrades
+sudo DEBIAN_FRONTEND=noninteractive \
+  apt-get \
+  -o Dpkg::Options::=--force-confold \
+  -o Dpkg::Options::=--force-confdef \
+  -y --allow-downgrades --allow-remove-essential --allow-change-held-packages \
+  install jq
+
+# Add firewall
+echo "y" | ufw enable
+
+# Open ports
+ufw allow ssh
+ufw allow https
+ufw allow 5223
+
+# Increase file descriptors limit
+echo 'fs.file-max = 1000000' >> /etc/sysctl.conf
+echo 'fs.inode-max = 1000000' >> /etc/sysctl.conf
+echo 'root soft nofile unlimited' >> /etc/security/limits.conf
+echo 'root hard nofile unlimited' >> /etc/security/limits.conf
+
+# Download latest release
+bin_dir="/opt/simplex/bin"
+binary="$bin_dir/smp-server"
+mkdir -p $bin_dir
+curl -L -o $binary https://github.com/simplex-chat/simplexmq/releases/latest/download/smp-server-ubuntu-20_04-x86-64
+chmod +x $binary
+
+# / Add to PATH
+cat > /etc/profile.d/simplex.sh << EOF
+#!/bin/bash
+
+export PATH="$PATH:$bin_dir"
+
+EOF
+# Add to PATH /
+
+# Source and test PATH
+source /etc/profile.d/simplex.sh
+smp-server --version
+
+# Initialize server
+init_opts=()
+
+[[ $ENABLE_STORE_LOG == "on" ]] && init_opts+=(-l)
+
+ip_address=$(curl ifconfig.me)
+init_opts+=(--ip $ip_address)
+
+[[ -n "$FQDN" ]] && init_opts+=(-n $FQDN)
+
+smp-server init "${init_opts[@]}"
+
+# Server fingerprint
+fingerprint=$(cat /etc/opt/simplex/fingerprint)
+
+# Determine server address to specify in welcome script and Linode tag
+# ! If FQDN was provided and used as part of server initialization, server's certificate will not pass validation at client
+# ! if client tries to connect by server's IP address, so we have to specify FQDN as server address in Linode tag and
+# ! in welcome script regardless of creation of A record in Linode
+# ! https://hackage.haskell.org/package/x509-validation-1.6.10/docs/src/Data-X509-Validation.html#validateCertificateName
+if [[ -n "$FQDN" ]]; then
+  server_address=$FQDN
+else
+  server_address=$ip_address
+fi
+
+# Set up welcome script
+on_login_script="/opt/simplex/on_login.sh"
+
+# / Welcome script
+cat > $on_login_script << EOF
+#!/bin/bash
+
+fingerprint=\$1
+server_address=\$2
+
+cat << EOF2
+********************************************************************************
+
+SMP server address: smp://\$fingerprint@\$server_address
+Check SMP server status with: systemctl status smp-server
+
+To keep this server secure, the UFW firewall is enabled.
+All ports are BLOCKED except 22 (SSH), 443 (HTTPS), 5223 (SMP server).
+
+********************************************************************************
+To stop seeing this message delete line - bash /opt/simplex/on_login.sh - from /root/.bashrc
+EOF2
+
+EOF
+# Welcome script /
+
+chmod +x $on_login_script
+echo "bash $on_login_script $fingerprint $server_address" >> /root/.bashrc
+
+# Create A record and update Linode's tags
+if [[ -n "$API_TOKEN" ]]; then
+  if [[ -n "$FQDN" ]]; then
+    domain_address=$(echo $FQDN | rev | cut -d "." -f 1,2 | rev)
+    domain_id=$(curl -H "Authorization: Bearer $API_TOKEN" https://api.linode.com/v4/domains \
+    | jq --arg da "$domain_address" '.data[] | select( .domain == $da ) | .id')
+    if [[ -n $domain_id ]]; then
+      curl \
+        -s -H "Content-Type: application/json" \
+        -H "Authorization: Bearer $API_TOKEN" \
+        -X POST -d "{\"type\":\"A\",\"name\":\"$FQDN\",\"target\":\"$ip_address\"}" \
+        https://api.linode.com/v4/domains/${domain_id}/records
+    fi
+  fi
+
+  version=$(smp-server --version | cut -d ' ' -f 3-)
+
+  curl \
+    -s -H "Content-Type: application/json" \
+    -H "Authorization: Bearer $API_TOKEN" \
+    -X PUT -d "{\"tags\":[\"$server_address\",\"$fingerprint\",\"$version\"]}" \
+    https://api.linode.com/v4/linode/instances/$LINODE_ID
+fi
+
+# / Create systemd service
+cat > /etc/systemd/system/smp-server.service << EOF
+[Unit]
+Description=SMP server
+
+[Service]
+Type=simple
+ExecStart=/bin/sh -c "exec $binary start >> /var/opt/simplex/smp-server.log 2>&1"
+KillSignal=SIGINT
+Restart=always
+RestartSec=10
+LimitNOFILE=1000000
+LimitNOFILESoft=1000000
+
+[Install]
+WantedBy=multi-user.target
+
+EOF
+# Create systemd service /
+
+# Start systemd service
+chmod 644 /etc/systemd/system/smp-server.service
+sudo systemctl enable smp-server
+sudo systemctl start smp-server
+
+# Reboot Linode to apply upgrades
+sudo reboot

scripts/update-smp-server.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+# systemd has to be configured to use SIGINT to save and restore undelivered messages after restart.
+# Add this to [Service] section:
+# KillSignal=SIGINT
+curl -L -o /opt/simplex/bin/smp-server-new https://github.com/simplex-chat/simplexmq/releases/latest/download/smp-server-ubuntu-20_04-x86-64
+systemctl stop smp-server
+cp /var/opt/simplex/smp-server-store.log /var/opt/simplex/smp-server-store.log.bak
+mv /opt/simplex/bin/smp-server /opt/simplex/bin/smp-server-old
+mv /opt/simplex/bin/smp-server-new /opt/simplex/bin/smp-server
+chmod +x /opt/simplex/bin/smp-server
+systemctl start smp-server

simplexmq.cabal

@@ -0,0 +1,401 @@
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.34.4.
+--
+-- see: https://github.com/sol/hpack
+
+name:           simplexmq
+version:        2.3.0
+synopsis:       SimpleXMQ message broker
+description:    This package includes <./docs/Simplex-Messaging-Server.html server>,
+                <./docs/Simplex-Messaging-Client.html client> and
+                <./docs/Simplex-Messaging-Agent.html agent> for SMP protocols:
+                .
+                * <https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md SMP protocol>
+                * <https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md SMP agent protocol>
+                .
+                See <https://github.com/simplex-chat/simplex-chat terminal chat prototype> built with SimpleXMQ broker.
+category:       Chat, Network, Web, System, Cryptography
+homepage:       https://github.com/simplex-chat/simplexmq#readme
+author:         simplex.chat
+maintainer:     chat@simplex.chat
+copyright:      2020-2022 simplex.chat
+license:        AGPL-3
+license-file:   LICENSE
+build-type:     Simple
+extra-source-files:
+    README.md
+    CHANGELOG.md
+
+flag swift
+  description: Enable swift JSON format
+  manual: True
+  default: False
+
+library
+  exposed-modules:
+      Simplex.Messaging.Agent
+      Simplex.Messaging.Agent.Client
+      Simplex.Messaging.Agent.Env.SQLite
+      Simplex.Messaging.Agent.Protocol
+      Simplex.Messaging.Agent.QueryString
+      Simplex.Messaging.Agent.RetryInterval
+      Simplex.Messaging.Agent.Server
+      Simplex.Messaging.Agent.Store
+      Simplex.Messaging.Agent.Store.SQLite
+      Simplex.Messaging.Agent.Store.SQLite.Migrations
+      Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220101_initial
+      Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220301_snd_queue_keys
+      Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220322_notifications
+      Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220404_ntf_subscriptions_draft
+      Simplex.Messaging.Client
+      Simplex.Messaging.Client.Agent
+      Simplex.Messaging.Crypto
+      Simplex.Messaging.Crypto.Ratchet
+      Simplex.Messaging.Encoding
+      Simplex.Messaging.Encoding.String
+      Simplex.Messaging.Notifications.Client
+      Simplex.Messaging.Notifications.Protocol
+      Simplex.Messaging.Notifications.Server
+      Simplex.Messaging.Notifications.Server.Env
+      Simplex.Messaging.Notifications.Server.Push.APNS
+      Simplex.Messaging.Notifications.Server.Store
+      Simplex.Messaging.Notifications.Transport
+      Simplex.Messaging.Parsers
+      Simplex.Messaging.Protocol
+      Simplex.Messaging.Server
+      Simplex.Messaging.Server.CLI
+      Simplex.Messaging.Server.Env.STM
+      Simplex.Messaging.Server.Expiration
+      Simplex.Messaging.Server.MsgStore
+      Simplex.Messaging.Server.MsgStore.STM
+      Simplex.Messaging.Server.QueueStore
+      Simplex.Messaging.Server.QueueStore.STM
+      Simplex.Messaging.Server.StoreLog
+      Simplex.Messaging.TMap
+      Simplex.Messaging.Transport
+      Simplex.Messaging.Transport.Client
+      Simplex.Messaging.Transport.HTTP2
+      Simplex.Messaging.Transport.HTTP2.Client
+      Simplex.Messaging.Transport.HTTP2.Server
+      Simplex.Messaging.Transport.KeepAlive
+      Simplex.Messaging.Transport.Server
+      Simplex.Messaging.Transport.WebSockets
+      Simplex.Messaging.Util
+      Simplex.Messaging.Version
+  other-modules:
+      Paths_simplexmq
+  hs-source-dirs:
+      src
+  ghc-options: -Wall -Wcompat -Werror=incomplete-patterns -Wredundant-constraints -Wincomplete-record-updates -Wincomplete-uni-patterns -Wunused-type-patterns
+  build-depends:
+      QuickCheck ==2.14.*
+    , aeson ==2.0.*
+    , ansi-terminal >=0.10 && <0.12
+    , asn1-encoding ==0.9.*
+    , asn1-types ==0.3.*
+    , async ==2.2.*
+    , attoparsec ==0.14.*
+    , base >=4.7 && <5
+    , base64-bytestring >=1.0 && <1.3
+    , bytestring ==0.10.*
+    , case-insensitive ==1.2.*
+    , composition ==1.0.*
+    , constraints >=0.12 && <0.14
+    , containers ==0.6.*
+    , cryptonite >=0.27 && <0.30
+    , cryptostore ==0.2.*
+    , data-default ==0.7.*
+    , direct-sqlite ==2.3.*
+    , directory ==1.3.*
+    , filepath ==1.4.*
+    , generic-random >=1.3 && <1.5
+    , http-types ==0.12.*
+    , http2 ==3.0.*
+    , ini ==0.4.*
+    , iso8601-time ==0.1.*
+    , memory ==0.15.*
+    , mtl ==2.2.*
+    , network ==3.1.2.*
+    , network-transport ==0.5.*
+    , optparse-applicative >=0.15 && <0.17
+    , process ==1.6.*
+    , random >=1.1 && <1.3
+    , simple-logger ==0.1.*
+    , sqlite-simple ==0.4.*
+    , stm ==2.5.*
+    , template-haskell ==2.16.*
+    , text ==1.2.*
+    , time ==1.9.*
+    , time-manager ==0.0.*
+    , tls >=1.5.7 && <1.6
+    , transformers ==0.5.*
+    , unliftio ==0.2.*
+    , unliftio-core ==0.2.*
+    , websockets ==0.12.*
+    , x509 ==1.7.*
+    , x509-store ==1.6.*
+    , x509-validation ==1.6.*
+  if flag(swift)
+    cpp-options: -DswiftJSON
+  default-language: Haskell2010
+
+executable ntf-server
+  main-is: Main.hs
+  other-modules:
+      Paths_simplexmq
+  hs-source-dirs:
+      apps/ntf-server
+  ghc-options: -Wall -Wcompat -Werror=incomplete-patterns -Wredundant-constraints -Wincomplete-record-updates -Wincomplete-uni-patterns -Wunused-type-patterns -threaded
+  build-depends:
+      QuickCheck ==2.14.*
+    , aeson ==2.0.*
+    , ansi-terminal >=0.10 && <0.12
+    , asn1-encoding ==0.9.*
+    , asn1-types ==0.3.*
+    , async ==2.2.*
+    , attoparsec ==0.14.*
+    , base >=4.7 && <5
+    , base64-bytestring >=1.0 && <1.3
+    , bytestring ==0.10.*
+    , case-insensitive ==1.2.*
+    , composition ==1.0.*
+    , constraints >=0.12 && <0.14
+    , containers ==0.6.*
+    , cryptonite >=0.27 && <0.30
+    , cryptostore ==0.2.*
+    , data-default ==0.7.*
+    , direct-sqlite ==2.3.*
+    , directory ==1.3.*
+    , filepath ==1.4.*
+    , generic-random >=1.3 && <1.5
+    , http-types ==0.12.*
+    , http2 ==3.0.*
+    , ini ==0.4.*
+    , iso8601-time ==0.1.*
+    , memory ==0.15.*
+    , mtl ==2.2.*
+    , network ==3.1.2.*
+    , network-transport ==0.5.*
+    , optparse-applicative >=0.15 && <0.17
+    , process ==1.6.*
+    , random >=1.1 && <1.3
+    , simple-logger ==0.1.*
+    , simplexmq
+    , sqlite-simple ==0.4.*
+    , stm ==2.5.*
+    , template-haskell ==2.16.*
+    , text ==1.2.*
+    , time ==1.9.*
+    , time-manager ==0.0.*
+    , tls >=1.5.7 && <1.6
+    , transformers ==0.5.*
+    , unliftio ==0.2.*
+    , unliftio-core ==0.2.*
+    , websockets ==0.12.*
+    , x509 ==1.7.*
+    , x509-store ==1.6.*
+    , x509-validation ==1.6.*
+  if flag(swift)
+    cpp-options: -DswiftJSON
+  default-language: Haskell2010
+
+executable smp-agent
+  main-is: Main.hs
+  other-modules:
+      Paths_simplexmq
+  hs-source-dirs:
+      apps/smp-agent
+  ghc-options: -Wall -Wcompat -Werror=incomplete-patterns -Wredundant-constraints -Wincomplete-record-updates -Wincomplete-uni-patterns -Wunused-type-patterns -threaded
+  build-depends:
+      QuickCheck ==2.14.*
+    , aeson ==2.0.*
+    , ansi-terminal >=0.10 && <0.12
+    , asn1-encoding ==0.9.*
+    , asn1-types ==0.3.*
+    , async ==2.2.*
+    , attoparsec ==0.14.*
+    , base >=4.7 && <5
+    , base64-bytestring >=1.0 && <1.3
+    , bytestring ==0.10.*
+    , case-insensitive ==1.2.*
+    , composition ==1.0.*
+    , constraints >=0.12 && <0.14
+    , containers ==0.6.*
+    , cryptonite >=0.27 && <0.30
+    , cryptostore ==0.2.*
+    , data-default ==0.7.*
+    , direct-sqlite ==2.3.*
+    , directory ==1.3.*
+    , filepath ==1.4.*
+    , generic-random >=1.3 && <1.5
+    , http-types ==0.12.*
+    , http2 ==3.0.*
+    , ini ==0.4.*
+    , iso8601-time ==0.1.*
+    , memory ==0.15.*
+    , mtl ==2.2.*
+    , network ==3.1.2.*
+    , network-transport ==0.5.*
+    , optparse-applicative >=0.15 && <0.17
+    , process ==1.6.*
+    , random >=1.1 && <1.3
+    , simple-logger ==0.1.*
+    , simplexmq
+    , sqlite-simple ==0.4.*
+    , stm ==2.5.*
+    , template-haskell ==2.16.*
+    , text ==1.2.*
+    , time ==1.9.*
+    , time-manager ==0.0.*
+    , tls >=1.5.7 && <1.6
+    , transformers ==0.5.*
+    , unliftio ==0.2.*
+    , unliftio-core ==0.2.*
+    , websockets ==0.12.*
+    , x509 ==1.7.*
+    , x509-store ==1.6.*
+    , x509-validation ==1.6.*
+  if flag(swift)
+    cpp-options: -DswiftJSON
+  default-language: Haskell2010
+
+executable smp-server
+  main-is: Main.hs
+  other-modules:
+      Paths_simplexmq
+  hs-source-dirs:
+      apps/smp-server
+  ghc-options: -Wall -Wcompat -Werror=incomplete-patterns -Wredundant-constraints -Wincomplete-record-updates -Wincomplete-uni-patterns -Wunused-type-patterns -threaded
+  build-depends:
+      QuickCheck ==2.14.*
+    , aeson ==2.0.*
+    , ansi-terminal >=0.10 && <0.12
+    , asn1-encoding ==0.9.*
+    , asn1-types ==0.3.*
+    , async ==2.2.*
+    , attoparsec ==0.14.*
+    , base >=4.7 && <5
+    , base64-bytestring >=1.0 && <1.3
+    , bytestring ==0.10.*
+    , case-insensitive ==1.2.*
+    , composition ==1.0.*
+    , constraints >=0.12 && <0.14
+    , containers ==0.6.*
+    , cryptonite >=0.27 && <0.30
+    , cryptostore ==0.2.*
+    , data-default ==0.7.*
+    , direct-sqlite ==2.3.*
+    , directory ==1.3.*
+    , filepath ==1.4.*
+    , generic-random >=1.3 && <1.5
+    , http-types ==0.12.*
+    , http2 ==3.0.*
+    , ini ==0.4.*
+    , iso8601-time ==0.1.*
+    , memory ==0.15.*
+    , mtl ==2.2.*
+    , network ==3.1.2.*
+    , network-transport ==0.5.*
+    , optparse-applicative >=0.15 && <0.17
+    , process ==1.6.*
+    , random >=1.1 && <1.3
+    , simple-logger ==0.1.*
+    , simplexmq
+    , sqlite-simple ==0.4.*
+    , stm ==2.5.*
+    , template-haskell ==2.16.*
+    , text ==1.2.*
+    , time ==1.9.*
+    , time-manager ==0.0.*
+    , tls >=1.5.7 && <1.6
+    , transformers ==0.5.*
+    , unliftio ==0.2.*
+    , unliftio-core ==0.2.*
+    , websockets ==0.12.*
+    , x509 ==1.7.*
+    , x509-store ==1.6.*
+    , x509-validation ==1.6.*
+  if flag(swift)
+    cpp-options: -DswiftJSON
+  default-language: Haskell2010
+
+test-suite smp-server-test
+  type: exitcode-stdio-1.0
+  main-is: Test.hs
+  other-modules:
+      AgentTests
+      AgentTests.ConnectionRequestTests
+      AgentTests.DoubleRatchetTests
+      AgentTests.FunctionalAPITests
+      AgentTests.NotificationTests
+      AgentTests.SchemaDump
+      AgentTests.SQLiteTests
+      CoreTests.EncodingTests
+      CoreTests.ProtocolErrorTests
+      CoreTests.VersionRangeTests
+      NtfClient
+      NtfServerTests
+      ServerTests
+      SMPAgentClient
+      SMPClient
+      Paths_simplexmq
+  hs-source-dirs:
+      tests
+  ghc-options: -Wall -Wcompat -Werror=incomplete-patterns -Wredundant-constraints -Wincomplete-record-updates -Wincomplete-uni-patterns -Wunused-type-patterns
+  build-depends:
+      HUnit ==1.6.*
+    , QuickCheck ==2.14.*
+    , aeson ==2.0.*
+    , ansi-terminal >=0.10 && <0.12
+    , asn1-encoding ==0.9.*
+    , asn1-types ==0.3.*
+    , async ==2.2.*
+    , attoparsec ==0.14.*
+    , base >=4.7 && <5
+    , base64-bytestring >=1.0 && <1.3
+    , bytestring ==0.10.*
+    , case-insensitive ==1.2.*
+    , composition ==1.0.*
+    , constraints >=0.12 && <0.14
+    , containers ==0.6.*
+    , cryptonite >=0.27 && <0.30
+    , cryptostore ==0.2.*
+    , data-default ==0.7.*
+    , direct-sqlite ==2.3.*
+    , directory ==1.3.*
+    , filepath ==1.4.*
+    , generic-random >=1.3 && <1.5
+    , hspec ==2.7.*
+    , hspec-core ==2.7.*
+    , http-types ==0.12.*
+    , http2 ==3.0.*
+    , ini ==0.4.*
+    , iso8601-time ==0.1.*
+    , memory ==0.15.*
+    , mtl ==2.2.*
+    , network ==3.1.2.*
+    , network-transport ==0.5.*
+    , optparse-applicative >=0.15 && <0.17
+    , process ==1.6.*
+    , random >=1.1 && <1.3
+    , simple-logger ==0.1.*
+    , simplexmq
+    , sqlite-simple ==0.4.*
+    , stm ==2.5.*
+    , template-haskell ==2.16.*
+    , text ==1.2.*
+    , time ==1.9.*
+    , time-manager ==0.0.*
+    , timeit ==2.0.*
+    , tls >=1.5.7 && <1.6
+    , transformers ==0.5.*
+    , unliftio ==0.2.*
+    , unliftio-core ==0.2.*
+    , websockets ==0.12.*
+    , x509 ==1.7.*
+    , x509-store ==1.6.*
+    , x509-validation ==1.6.*
+  if flag(swift)
+    cpp-options: -DswiftJSON
+  default-language: Haskell2010

src/Env/STM.hs

@@ -1,75 +0,0 @@
-{-# LANGUAGE DuplicateRecordFields #-}
-{-# LANGUAGE NamedFieldPuns #-}
-
-module Env.STM where
-
-import Control.Concurrent (ThreadId)
-import Control.Monad.IO.Unlift
-import Crypto.Random
-import Data.Map.Strict (Map)
-import qualified Data.Map.Strict as M
-import MsgStore.STM
-import Network.Socket (ServiceName)
-import Numeric.Natural
-import QueueStore.STM
-import Transmission
-import UnliftIO.STM
-
-data Config = Config
-  { tcpPort :: ServiceName,
-    tbqSize :: Natural,
-    queueIdBytes :: Int,
-    msgIdBytes :: Int
-  }
-
-data Env = Env
-  { config :: Config,
-    server :: Server,
-    queueStore :: QueueStore,
-    msgStore :: STMMsgStore,
-    idsDrg :: TVar ChaChaDRG
-  }
-
-data Server = Server
-  { subscribedQ :: TBQueue (RecipientId, Client),
-    subscribers :: TVar (Map RecipientId Client)
-  }
-
-data Client = Client
-  { subscriptions :: TVar (Map RecipientId Sub),
-    rcvQ :: TBQueue Signed,
-    sndQ :: TBQueue Signed
-  }
-
-data SubscriptionThread = NoSub | SubPending | SubThread ThreadId
-
-data Sub = Sub
-  { subThread :: SubscriptionThread,
-    delivered :: TMVar ()
-  }
-
-newServer :: Natural -> STM Server
-newServer qSize = do
-  subscribedQ <- newTBQueue qSize
-  subscribers <- newTVar M.empty
-  return Server {subscribedQ, subscribers}
-
-newClient :: Natural -> STM Client
-newClient qSize = do
-  subscriptions <- newTVar M.empty
-  rcvQ <- newTBQueue qSize
-  sndQ <- newTBQueue qSize
-  return Client {subscriptions, rcvQ, sndQ}
-
-newSubscription :: STM Sub
-newSubscription = do
-  delivered <- newEmptyTMVar
-  return Sub {subThread = NoSub, delivered}
-
-newEnv :: (MonadUnliftIO m, MonadRandom m) => Config -> m Env
-newEnv config = do
-  server <- atomically $ newServer (tbqSize config)
-  queueStore <- atomically newQueueStore
-  msgStore <- atomically newMsgStore
-  idsDrg <- drgNew >>= newTVarIO
-  return Env {config, server, queueStore, msgStore, idsDrg}

src/MsgStore.hs

@@ -1,22 +0,0 @@
-{-# LANGUAGE FunctionalDependencies #-}
-
-module MsgStore where
-
-import Data.Time.Clock
-import Transmission
-
-data Message = Message
-  { msgId :: Encoded,
-    ts :: UTCTime,
-    msgBody :: MsgBody
-  }
-
-class MonadMsgStore s q m | s -> q where
-  getMsgQueue :: s -> RecipientId -> m q
-  delMsgQueue :: s -> RecipientId -> m ()
-
-class MonadMsgQueue q m where
-  writeMsg :: q -> Message -> m () -- non blocking
-  tryPeekMsg :: q -> m (Maybe Message) -- non blocking
-  peekMsg :: q -> m Message -- blocking
-  tryDelPeekMsg :: q -> m (Maybe Message) -- atomic delete (== read) last and peek next message, if available

src/MsgStore/STM.hs

@@ -1,51 +0,0 @@
-{-# LANGUAGE ConstraintKinds #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE FlexibleInstances #-}
-{-# LANGUAGE InstanceSigs #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-
-module MsgStore.STM where
-
-import Data.Map.Strict (Map)
-import qualified Data.Map.Strict as M
-import MsgStore
-import Transmission
-import UnliftIO.STM
-
-newtype MsgQueue = MsgQueue {msgQueue :: TQueue Message}
-
-newtype MsgStoreData = MsgStoreData {messages :: Map RecipientId MsgQueue}
-
-type STMMsgStore = TVar MsgStoreData
-
-newMsgStore :: STM STMMsgStore
-newMsgStore = newTVar $ MsgStoreData M.empty
-
-instance MonadMsgStore STMMsgStore MsgQueue STM where
-  getMsgQueue :: STMMsgStore -> RecipientId -> STM MsgQueue
-  getMsgQueue store rId = do
-    m <- messages <$> readTVar store
-    maybe (newQ m) return $ M.lookup rId m
-    where
-      newQ m' = do
-        q <- MsgQueue <$> newTQueue
-        writeTVar store . MsgStoreData $ M.insert rId q m'
-        return q
-
-  delMsgQueue :: STMMsgStore -> RecipientId -> STM ()
-  delMsgQueue store rId =
-    modifyTVar store $ MsgStoreData . M.delete rId . messages
-
-instance MonadMsgQueue MsgQueue STM where
-  writeMsg :: MsgQueue -> Message -> STM ()
-  writeMsg = writeTQueue . msgQueue
-
-  tryPeekMsg :: MsgQueue -> STM (Maybe Message)
-  tryPeekMsg = tryPeekTQueue . msgQueue
-
-  peekMsg :: MsgQueue -> STM Message
-  peekMsg = peekTQueue . msgQueue
-
-  -- atomic delete (== read) last and peek next message if available
-  tryDelPeekMsg :: MsgQueue -> STM (Maybe Message)
-  tryDelPeekMsg (MsgQueue q) = tryReadTQueue q >> tryPeekTQueue q

src/QueueStore.hs

@@ -1,35 +0,0 @@
-{-# LANGUAGE DataKinds #-}
-{-# LANGUAGE KindSignatures #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE NamedFieldPuns #-}
-
-module QueueStore where
-
-import Transmission
-
-data QueueRec = QueueRec
-  { recipientId :: QueueId,
-    senderId :: QueueId,
-    recipientKey :: PublicKey,
-    senderKey :: Maybe PublicKey,
-    status :: QueueStatus
-  }
-
-data QueueStatus = QueueActive | QueueOff
-
-class MonadQueueStore s m where
-  addQueue :: s -> RecipientKey -> (RecipientId, SenderId) -> m (Either ErrorType ())
-  getQueue :: s -> SParty (a :: Party) -> QueueId -> m (Either ErrorType QueueRec)
-  secureQueue :: s -> RecipientId -> SenderKey -> m (Either ErrorType ())
-  suspendQueue :: s -> RecipientId -> m (Either ErrorType ())
-  deleteQueue :: s -> RecipientId -> m (Either ErrorType ())
-
-mkQueueRec :: RecipientKey -> (RecipientId, SenderId) -> QueueRec
-mkQueueRec recipientKey (recipientId, senderId) =
-  QueueRec
-    { recipientId,
-      senderId,
-      recipientKey,
-      senderKey = Nothing,
-      status = QueueActive
-    }

src/QueueStore/STM.hs

@@ -1,92 +0,0 @@
-{-# LANGUAGE DataKinds #-}
-{-# LANGUAGE FlexibleInstances #-}
-{-# LANGUAGE GADTs #-}
-{-# LANGUAGE InstanceSigs #-}
-{-# LANGUAGE KindSignatures #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE NamedFieldPuns #-}
-{-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE UndecidableInstances #-}
-
-module QueueStore.STM where
-
-import Data.Map.Strict (Map)
-import qualified Data.Map.Strict as M
-import QueueStore
-import Transmission
-import UnliftIO.STM
-
-data QueueStoreData = QueueStoreData
-  { queues :: Map RecipientId QueueRec,
-    senders :: Map SenderId RecipientId
-  }
-
-type QueueStore = TVar QueueStoreData
-
-newQueueStore :: STM QueueStore
-newQueueStore = newTVar QueueStoreData {queues = M.empty, senders = M.empty}
-
-instance MonadQueueStore QueueStore STM where
-  addQueue :: QueueStore -> RecipientKey -> (RecipientId, SenderId) -> STM (Either ErrorType ())
-  addQueue store rKey ids@(rId, sId) = do
-    cs@QueueStoreData {queues, senders} <- readTVar store
-    if M.member rId queues || M.member sId senders
-      then return $ Left DUPLICATE
-      else do
-        writeTVar store $
-          cs
-            { queues = M.insert rId (mkQueueRec rKey ids) queues,
-              senders = M.insert sId rId senders
-            }
-        return $ Right ()
-
-  getQueue :: QueueStore -> SParty (p :: Party) -> QueueId -> STM (Either ErrorType QueueRec)
-  getQueue store SRecipient rId = do
-    cs <- readTVar store
-    return $ getRcpQueue cs rId
-  getQueue store SSender sId = do
-    cs <- readTVar store
-    let rId = M.lookup sId $ senders cs
-    return $ maybe (Left AUTH) (getRcpQueue cs) rId
-  getQueue _ SBroker _ =
-    return $ Left INTERNAL
-
-  secureQueue store rId sKey =
-    updateQueues store rId $ \cs c ->
-      case senderKey c of
-        Just _ -> (Left AUTH, cs)
-        _ -> (Right (), cs {queues = M.insert rId c {senderKey = Just sKey} (queues cs)})
-
-  suspendQueue :: QueueStore -> RecipientId -> STM (Either ErrorType ())
-  suspendQueue store rId =
-    updateQueues store rId $ \cs c ->
-      (Right (), cs {queues = M.insert rId c {status = QueueOff} (queues cs)})
-
-  deleteQueue :: QueueStore -> RecipientId -> STM (Either ErrorType ())
-  deleteQueue store rId =
-    updateQueues store rId $ \cs c ->
-      ( Right (),
-        cs
-          { queues = M.delete rId (queues cs),
-            senders = M.delete (senderId c) (senders cs)
-          }
-      )
-
-updateQueues ::
-  QueueStore ->
-  RecipientId ->
-  (QueueStoreData -> QueueRec -> (Either ErrorType (), QueueStoreData)) ->
-  STM (Either ErrorType ())
-updateQueues store rId update = do
-  cs <- readTVar store
-  let conn = getRcpQueue cs rId
-  either (return . Left) (_update cs) conn
-  where
-    _update cs c = do
-      let (res, cs') = update cs c
-      writeTVar store cs'
-      return res
-
-getRcpQueue :: QueueStoreData -> RecipientId -> Either ErrorType QueueRec
-getRcpQueue cs rId = maybe (Left AUTH) Right . M.lookup rId $ queues cs

src/Server.hs

@@ -1,279 +0,0 @@
-{-# LANGUAGE DataKinds #-}
-{-# LANGUAGE DuplicateRecordFields #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE GADTs #-}
-{-# LANGUAGE KindSignatures #-}
-{-# LANGUAGE LambdaCase #-}
-{-# LANGUAGE NamedFieldPuns #-}
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TupleSections #-}
-
-module Server (runSMPServer) where
-
-import Control.Concurrent.STM (stateTVar)
-import Control.Monad
-import Control.Monad.IO.Unlift
-import Control.Monad.Reader
-import Crypto.Random
-import Data.ByteString.Char8 (ByteString)
-import qualified Data.ByteString.Char8 as B
-import Data.Functor (($>))
-import qualified Data.Map.Strict as M
-import Data.Time.Clock
-import Env.STM
-import MsgStore
-import MsgStore.STM (MsgQueue)
-import QueueStore
-import QueueStore.STM (QueueStore)
-import Transmission
-import Transport
-import UnliftIO.Async
-import UnliftIO.Concurrent
-import UnliftIO.Exception
-import UnliftIO.IO
-import UnliftIO.STM
-
-runSMPServer :: (MonadRandom m, MonadUnliftIO m) => Config -> m ()
-runSMPServer cfg@Config {tcpPort} = do
-  env <- newEnv cfg
-  runReaderT smpServer env
-  where
-    smpServer :: (MonadUnliftIO m, MonadReader Env m) => m ()
-    smpServer = do
-      s <- asks server
-      race_ (runTCPServer tcpPort runClient) (serverThread s)
-
-    serverThread :: MonadUnliftIO m => Server -> m ()
-    serverThread Server {subscribedQ, subscribers} = forever . atomically $ do
-      (rId, clnt) <- readTBQueue subscribedQ
-      cs <- readTVar subscribers
-      case M.lookup rId cs of
-        Just Client {rcvQ} -> writeTBQueue rcvQ (rId, Cmd SBroker END)
-        Nothing -> return ()
-      writeTVar subscribers $ M.insert rId clnt cs
-
-runClient :: (MonadUnliftIO m, MonadReader Env m) => Handle -> m ()
-runClient h = do
-  putLn h "Welcome to SMP"
-  q <- asks $ tbqSize . config
-  c <- atomically $ newClient q
-  s <- asks server
-  raceAny_ [send h c, client c s, receive h c]
-    `finally` cancelSubscribers c
-
-cancelSubscribers :: (MonadUnliftIO m) => Client -> m ()
-cancelSubscribers Client {subscriptions} =
-  readTVarIO subscriptions >>= mapM_ cancelSub
-
-cancelSub :: (MonadUnliftIO m) => Sub -> m ()
-cancelSub = \case
-  Sub {subThread = SubThread t} -> killThread t
-  _ -> return ()
-
-raceAny_ :: MonadUnliftIO m => [m a] -> m ()
-raceAny_ = r []
-  where
-    r as (m : ms) = withAsync m $ \a -> r (a : as) ms
-    r as [] = void $ waitAnyCancel as
-
-receive :: (MonadUnliftIO m, MonadReader Env m) => Handle -> Client -> m ()
-receive h Client {rcvQ} = forever $ do
-  (signature, (queueId, cmdOrError)) <- tGet fromClient h
-  signed <- case cmdOrError of
-    Left e -> return . mkResp queueId $ ERR e
-    Right cmd -> verifyTransmission signature queueId cmd
-  atomically $ writeTBQueue rcvQ signed
-
-send :: MonadUnliftIO m => Handle -> Client -> m ()
-send h Client {sndQ} = forever $ do
-  signed <- atomically $ readTBQueue sndQ
-  tPut h (B.empty, signed)
-
-mkResp :: QueueId -> Command 'Broker -> Signed
-mkResp queueId command = (queueId, Cmd SBroker command)
-
-verifyTransmission :: forall m. (MonadUnliftIO m, MonadReader Env m) => Signature -> QueueId -> Cmd -> m Signed
-verifyTransmission signature queueId cmd = do
-  (queueId,) <$> case cmd of
-    Cmd SBroker _ -> return $ smpErr INTERNAL -- it can only be client command, because `fromClient` was used
-    Cmd SRecipient (NEW _) -> return cmd
-    Cmd SRecipient _ -> withQueueRec SRecipient $ verifySignature . recipientKey
-    Cmd SSender (SEND _) -> withQueueRec SSender $ verifySend . senderKey
-  where
-    withQueueRec :: SParty (p :: Party) -> (QueueRec -> m Cmd) -> m Cmd
-    withQueueRec party f = do
-      st <- asks queueStore
-      qr <- atomically $ getQueue st party queueId
-      either (return . smpErr) f qr
-    verifySend :: Maybe PublicKey -> m Cmd
-    verifySend
-      | B.null signature = return . maybe cmd (const authErr)
-      | otherwise = maybe (return authErr) verifySignature
-    -- TODO stub
-    verifySignature :: PublicKey -> m Cmd
-    verifySignature key = return $ if signature == key then cmd else authErr
-
-    smpErr e = Cmd SBroker $ ERR e
-    authErr = smpErr AUTH
-
-client :: forall m. (MonadUnliftIO m, MonadReader Env m) => Client -> Server -> m ()
-client clnt@Client {subscriptions, rcvQ, sndQ} Server {subscribedQ} =
-  forever $
-    atomically (readTBQueue rcvQ)
-      >>= processCommand
-      >>= atomically . writeTBQueue sndQ
-  where
-    processCommand :: Signed -> m Signed
-    processCommand (queueId, cmd) = do
-      st <- asks queueStore
-      case cmd of
-        Cmd SBroker END -> unsubscribeQueue $> (queueId, cmd)
-        Cmd SBroker _ -> return (queueId, cmd)
-        Cmd SSender (SEND msgBody) -> sendMessage st msgBody
-        Cmd SRecipient command -> case command of
-          NEW rKey -> createQueue st rKey
-          SUB -> subscribeQueue queueId
-          ACK -> acknowledgeMsg
-          KEY sKey -> okResp <$> atomically (secureQueue st queueId sKey)
-          OFF -> okResp <$> atomically (suspendQueue st queueId)
-          DEL -> delQueueAndMsgs st
-      where
-        createQueue :: QueueStore -> RecipientKey -> m Signed
-        createQueue st rKey = mkResp B.empty <$> addSubscribe
-          where
-            addSubscribe =
-              addQueueRetry 3 >>= \case
-                Left e -> return $ ERR e
-                Right (rId, sId) -> subscribeQueue rId $> IDS rId sId
-
-            addQueueRetry :: Int -> m (Either ErrorType (RecipientId, SenderId))
-            addQueueRetry 0 = return $ Left INTERNAL
-            addQueueRetry n = do
-              ids <- getIds
-              atomically (addQueue st rKey ids) >>= \case
-                Left DUPLICATE -> addQueueRetry $ n - 1
-                Left e -> return $ Left e
-                Right _ -> return $ Right ids
-
-            getIds :: m (RecipientId, SenderId)
-            getIds = do
-              n <- asks $ queueIdBytes . config
-              liftM2 (,) (randomId n) (randomId n)
-
-        subscribeQueue :: RecipientId -> m Signed
-        subscribeQueue rId =
-          atomically (getSubscription rId) >>= deliverMessage tryPeekMsg rId
-
-        getSubscription :: RecipientId -> STM Sub
-        getSubscription rId = do
-          subs <- readTVar subscriptions
-          case M.lookup rId subs of
-            Just s -> tryTakeTMVar (delivered s) $> s
-            Nothing -> do
-              writeTBQueue subscribedQ (rId, clnt)
-              s <- newSubscription
-              writeTVar subscriptions $ M.insert rId s subs
-              return s
-
-        unsubscribeQueue :: m ()
-        unsubscribeQueue = do
-          sub <- atomically . stateTVar subscriptions $
-            \cs -> (M.lookup queueId cs, M.delete queueId cs)
-          mapM_ cancelSub sub
-
-        acknowledgeMsg :: m Signed
-        acknowledgeMsg =
-          atomically (withSub queueId $ \s -> const s <$$> tryTakeTMVar (delivered s))
-            >>= \case
-              Just (Just s) -> deliverMessage tryDelPeekMsg queueId s
-              _ -> return $ err PROHIBITED
-
-        withSub :: RecipientId -> (Sub -> STM a) -> STM (Maybe a)
-        withSub rId f = readTVar subscriptions >>= mapM f . M.lookup rId
-
-        sendMessage :: QueueStore -> MsgBody -> m Signed
-        sendMessage st msgBody = do
-          qr <- atomically $ getQueue st SSender queueId
-          either (return . err) storeMessage qr
-          where
-            mkMessage :: m Message
-            mkMessage = do
-              msgId <- asks (msgIdBytes . config) >>= randomId
-              ts <- liftIO getCurrentTime
-              return $ Message {msgId, ts, msgBody}
-
-            storeMessage :: QueueRec -> m Signed
-            storeMessage qr = case status qr of
-              QueueOff -> return $ err AUTH
-              QueueActive -> do
-                ms <- asks msgStore
-                msg <- mkMessage
-                atomically $ do
-                  q <- getMsgQueue ms (recipientId qr)
-                  writeMsg q msg
-                  return ok
-
-        deliverMessage :: (MsgQueue -> STM (Maybe Message)) -> RecipientId -> Sub -> m Signed
-        deliverMessage tryPeek rId = \case
-          Sub {subThread = NoSub} -> do
-            ms <- asks msgStore
-            q <- atomically $ getMsgQueue ms rId
-            atomically (tryPeek q) >>= \case
-              Nothing -> forkSub q $> ok
-              Just msg -> atomically setDelivered $> msgResp rId msg
-          _ -> return ok
-          where
-            forkSub :: MsgQueue -> m ()
-            forkSub q = do
-              atomically . setSub $ \s -> s {subThread = SubPending}
-              t <- forkIO $ subscriber q
-              atomically . setSub $ \case
-                s@Sub {subThread = SubPending} -> s {subThread = SubThread t}
-                s -> s
-
-            subscriber :: MsgQueue -> m ()
-            subscriber q = atomically $ do
-              msg <- peekMsg q
-              writeTBQueue sndQ $ msgResp rId msg
-              setSub (\s -> s {subThread = NoSub})
-              void setDelivered
-
-            setSub :: (Sub -> Sub) -> STM ()
-            setSub f = modifyTVar subscriptions $ M.adjust f rId
-
-            setDelivered :: STM (Maybe Bool)
-            setDelivered = withSub rId $ \s -> tryPutTMVar (delivered s) ()
-
-        delQueueAndMsgs :: QueueStore -> m Signed
-        delQueueAndMsgs st = do
-          ms <- asks msgStore
-          atomically $
-            deleteQueue st queueId >>= \case
-              Left e -> return $ err e
-              Right _ -> delMsgQueue ms queueId $> ok
-
-        ok :: Signed
-        ok = mkResp queueId OK
-
-        err :: ErrorType -> Signed
-        err = mkResp queueId . ERR
-
-        okResp :: Either ErrorType () -> Signed
-        okResp = either err $ const ok
-
-        msgResp :: RecipientId -> Message -> Signed
-        msgResp rId Message {msgId, ts, msgBody} = mkResp rId $ MSG msgId ts msgBody
-
-randomId :: (MonadUnliftIO m, MonadReader Env m) => Int -> m Encoded
-randomId n = do
-  gVar <- asks idsDrg
-  atomically (randomBytes n gVar)
-
-randomBytes :: Int -> TVar ChaChaDRG -> STM ByteString
-randomBytes n gVar = do
-  g <- readTVar gVar
-  let (bytes, g') = randomBytesGenerate n g
-  writeTVar gVar g'
-  return bytes

src/Simplex/Messaging/Agent.hs

@@ -0,0 +1,916 @@
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedLists #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+
+-- |
+-- Module      : Simplex.Messaging.Agent
+-- Copyright   : (c) simplex.chat
+-- License     : AGPL-3
+--
+-- Maintainer  : chat@simplex.chat
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- This module defines SMP protocol agent with SQLite persistence.
+--
+-- See https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md
+module Simplex.Messaging.Agent
+  ( -- * queue-based SMP agent
+    getAgentClient,
+    runAgentClient,
+
+    -- * SMP agent functional API
+    AgentClient (..),
+    AgentMonad,
+    AgentErrorMonad,
+    getSMPAgentClient,
+    disconnectAgentClient,
+    resumeAgentClient,
+    withAgentLock,
+    createConnection,
+    joinConnection,
+    allowConnection,
+    acceptContact,
+    rejectContact,
+    subscribeConnection,
+    resubscribeConnection,
+    sendMessage,
+    ackMessage,
+    suspendConnection,
+    deleteConnection,
+    setSMPServers,
+    setNtfServers,
+    registerNtfToken,
+    verifyNtfToken,
+    enableNtfCron,
+    checkNtfToken,
+    deleteNtfToken,
+    logConnection,
+  )
+where
+
+import Control.Concurrent.STM (stateTVar)
+import Control.Logger.Simple (logInfo, showText)
+import Control.Monad.Except
+import Control.Monad.IO.Unlift (MonadUnliftIO)
+import Control.Monad.Reader
+import Crypto.Random (MonadRandom)
+import Data.Bifunctor (bimap, first, second)
+import Data.ByteString.Char8 (ByteString)
+import Data.Composition ((.:), (.:.))
+import Data.Functor (($>))
+import Data.List.NonEmpty (NonEmpty (..))
+import qualified Data.List.NonEmpty as L
+import qualified Data.Map.Strict as M
+import Data.Maybe (isJust)
+import qualified Data.Text as T
+import Data.Time.Clock
+import Data.Time.Clock.System (systemToUTCTime)
+import Data.Word (Word16)
+import Database.SQLite.Simple (SQLError)
+import Simplex.Messaging.Agent.Client
+import Simplex.Messaging.Agent.Env.SQLite
+import Simplex.Messaging.Agent.Protocol
+import Simplex.Messaging.Agent.RetryInterval
+import Simplex.Messaging.Agent.Store
+import Simplex.Messaging.Agent.Store.SQLite (SQLiteStore)
+import Simplex.Messaging.Client (ProtocolClient (..), ServerTransmission)
+import qualified Simplex.Messaging.Crypto as C
+import qualified Simplex.Messaging.Crypto.Ratchet as CR
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Notifications.Client
+import Simplex.Messaging.Notifications.Protocol (DeviceToken, NtfRegCode (NtfRegCode), NtfTknStatus (..))
+import Simplex.Messaging.Parsers (parse)
+import Simplex.Messaging.Protocol (BrokerMsg, ErrorType (AUTH), MsgBody)
+import qualified Simplex.Messaging.Protocol as SMP
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Util (bshow, liftError, tryError, unlessM, ($>>=))
+import Simplex.Messaging.Version
+import System.Random (randomR)
+import UnliftIO.Async (async, race_)
+import qualified UnliftIO.Exception as E
+import UnliftIO.STM
+
+-- | Creates an SMP agent client instance
+getSMPAgentClient :: (MonadRandom m, MonadUnliftIO m) => AgentConfig -> InitialAgentServers -> m AgentClient
+getSMPAgentClient cfg initServers = newSMPAgentEnv cfg >>= runReaderT runAgent
+  where
+    runAgent = do
+      c <- getAgentClient initServers
+      action <- async $ subscriber c `E.finally` disconnectAgentClient c
+      pure c {smpSubscriber = action}
+
+disconnectAgentClient :: MonadUnliftIO m => AgentClient -> m ()
+disconnectAgentClient c = closeAgentClient c >> logConnection c False
+
+resumeAgentClient :: MonadIO m => AgentClient -> m ()
+resumeAgentClient c = atomically $ writeTVar (active c) True
+
+-- |
+type AgentErrorMonad m = (MonadUnliftIO m, MonadError AgentErrorType m)
+
+-- | Create SMP agent connection (NEW command)
+createConnection :: AgentErrorMonad m => AgentClient -> SConnectionMode c -> m (ConnId, ConnectionRequestUri c)
+createConnection c cMode = withAgentEnv c $ newConn c "" cMode
+
+-- | Join SMP agent connection (JOIN command)
+joinConnection :: AgentErrorMonad m => AgentClient -> ConnectionRequestUri c -> ConnInfo -> m ConnId
+joinConnection c = withAgentEnv c .: joinConn c ""
+
+-- | Allow connection to continue after CONF notification (LET command)
+allowConnection :: AgentErrorMonad m => AgentClient -> ConnId -> ConfirmationId -> ConnInfo -> m ()
+allowConnection c = withAgentEnv c .:. allowConnection' c
+
+-- | Accept contact after REQ notification (ACPT command)
+acceptContact :: AgentErrorMonad m => AgentClient -> ConfirmationId -> ConnInfo -> m ConnId
+acceptContact c = withAgentEnv c .: acceptContact' c ""
+
+-- | Reject contact (RJCT command)
+rejectContact :: AgentErrorMonad m => AgentClient -> ConnId -> ConfirmationId -> m ()
+rejectContact c = withAgentEnv c .: rejectContact' c
+
+-- | Subscribe to receive connection messages (SUB command)
+subscribeConnection :: AgentErrorMonad m => AgentClient -> ConnId -> m ()
+subscribeConnection c = withAgentEnv c . subscribeConnection' c
+
+resubscribeConnection :: AgentErrorMonad m => AgentClient -> ConnId -> m ()
+resubscribeConnection c = withAgentEnv c . resubscribeConnection' c
+
+-- | Send message to the connection (SEND command)
+sendMessage :: AgentErrorMonad m => AgentClient -> ConnId -> MsgBody -> m AgentMsgId
+sendMessage c = withAgentEnv c .: sendMessage' c
+
+ackMessage :: AgentErrorMonad m => AgentClient -> ConnId -> AgentMsgId -> m ()
+ackMessage c = withAgentEnv c .: ackMessage' c
+
+-- | Suspend SMP agent connection (OFF command)
+suspendConnection :: AgentErrorMonad m => AgentClient -> ConnId -> m ()
+suspendConnection c = withAgentEnv c . suspendConnection' c
+
+-- | Delete SMP agent connection (DEL command)
+deleteConnection :: AgentErrorMonad m => AgentClient -> ConnId -> m ()
+deleteConnection c = withAgentEnv c . deleteConnection' c
+
+-- | Change servers to be used for creating new queues
+setSMPServers :: AgentErrorMonad m => AgentClient -> NonEmpty SMPServer -> m ()
+setSMPServers c = withAgentEnv c . setSMPServers' c
+
+setNtfServers :: AgentErrorMonad m => AgentClient -> [NtfServer] -> m ()
+setNtfServers c = withAgentEnv c . setNtfServers' c
+
+-- | Register device notifications token
+registerNtfToken :: AgentErrorMonad m => AgentClient -> DeviceToken -> m NtfTknStatus
+registerNtfToken c = withAgentEnv c . registerNtfToken' c
+
+-- | Verify device notifications token
+verifyNtfToken :: AgentErrorMonad m => AgentClient -> DeviceToken -> ByteString -> C.CbNonce -> m ()
+verifyNtfToken c = withAgentEnv c .:. verifyNtfToken' c
+
+-- | Enable/disable periodic notifications
+enableNtfCron :: AgentErrorMonad m => AgentClient -> DeviceToken -> Word16 -> m ()
+enableNtfCron c = withAgentEnv c .: enableNtfCron' c
+
+checkNtfToken :: AgentErrorMonad m => AgentClient -> DeviceToken -> m NtfTknStatus
+checkNtfToken c = withAgentEnv c . checkNtfToken' c
+
+deleteNtfToken :: AgentErrorMonad m => AgentClient -> DeviceToken -> m ()
+deleteNtfToken c = withAgentEnv c . deleteNtfToken' c
+
+withAgentEnv :: AgentClient -> ReaderT Env m a -> m a
+withAgentEnv c = (`runReaderT` agentEnv c)
+
+-- withAgentClient :: AgentErrorMonad m => AgentClient -> ReaderT Env m a -> m a
+-- withAgentClient c = withAgentLock c . withAgentEnv c
+
+-- | Creates an SMP agent client instance that receives commands and sends responses via 'TBQueue's.
+getAgentClient :: (MonadUnliftIO m, MonadReader Env m) => InitialAgentServers -> m AgentClient
+getAgentClient initServers = ask >>= atomically . newAgentClient initServers
+
+logConnection :: MonadUnliftIO m => AgentClient -> Bool -> m ()
+logConnection c connected =
+  let event = if connected then "connected to" else "disconnected from"
+   in logInfo $ T.unwords ["client", showText (clientId c), event, "Agent"]
+
+-- | Runs an SMP agent instance that receives commands and sends responses via 'TBQueue's.
+runAgentClient :: (MonadUnliftIO m, MonadReader Env m) => AgentClient -> m ()
+runAgentClient c = race_ (subscriber c) (client c)
+
+client :: forall m. (MonadUnliftIO m, MonadReader Env m) => AgentClient -> m ()
+client c@AgentClient {rcvQ, subQ} = forever $ do
+  (corrId, connId, cmd) <- atomically $ readTBQueue rcvQ
+  withAgentLock c (runExceptT $ processCommand c (connId, cmd))
+    >>= atomically . writeTBQueue subQ . \case
+      Left e -> (corrId, connId, ERR e)
+      Right (connId', resp) -> (corrId, connId', resp)
+
+withStore ::
+  AgentMonad m =>
+  (forall m'. (MonadUnliftIO m', MonadError StoreError m') => SQLiteStore -> m' a) ->
+  m a
+withStore action = do
+  st <- asks store
+  runExceptT (action st `E.catch` handleInternal) >>= \case
+    Right c -> return c
+    Left e -> throwError $ storeError e
+  where
+    -- TODO when parsing exception happens in store, the agent hangs;
+    -- changing SQLError to SomeException does not help
+    handleInternal :: (MonadError StoreError m') => SQLError -> m' a
+    handleInternal e = throwError . SEInternal $ bshow e
+    storeError :: StoreError -> AgentErrorType
+    storeError = \case
+      SEConnNotFound -> CONN NOT_FOUND
+      SEConnDuplicate -> CONN DUPLICATE
+      SEBadConnType CRcv -> CONN SIMPLEX
+      SEBadConnType CSnd -> CONN SIMPLEX
+      SEInvitationNotFound -> CMD PROHIBITED
+      e -> INTERNAL $ show e
+
+-- | execute any SMP agent command
+processCommand :: forall m. AgentMonad m => AgentClient -> (ConnId, ACommand 'Client) -> m (ConnId, ACommand 'Agent)
+processCommand c (connId, cmd) = case cmd of
+  NEW (ACM cMode) -> second (INV . ACR cMode) <$> newConn c connId cMode
+  JOIN (ACR _ cReq) connInfo -> (,OK) <$> joinConn c connId cReq connInfo
+  LET confId ownCInfo -> allowConnection' c connId confId ownCInfo $> (connId, OK)
+  ACPT invId ownCInfo -> (,OK) <$> acceptContact' c connId invId ownCInfo
+  RJCT invId -> rejectContact' c connId invId $> (connId, OK)
+  SUB -> subscribeConnection' c connId $> (connId, OK)
+  SEND msgBody -> (connId,) . MID <$> sendMessage' c connId msgBody
+  ACK msgId -> ackMessage' c connId msgId $> (connId, OK)
+  OFF -> suspendConnection' c connId $> (connId, OK)
+  DEL -> deleteConnection' c connId $> (connId, OK)
+
+newConn :: AgentMonad m => AgentClient -> ConnId -> SConnectionMode c -> m (ConnId, ConnectionRequestUri c)
+newConn c connId cMode = do
+  srv <- getSMPServer c
+  (rq, qUri) <- newRcvQueue c srv
+  g <- asks idsDrg
+  let cData = ConnData {connId}
+  connId' <- withStore $ \st -> createRcvConn st g cData rq cMode
+  addSubscription c rq connId'
+  let crData = ConnReqUriData simplexChat smpAgentVRange [qUri]
+  case cMode of
+    SCMContact -> pure (connId', CRContactUri crData)
+    SCMInvitation -> do
+      (pk1, pk2, e2eRcvParams) <- liftIO $ CR.generateE2EParams CR.e2eEncryptVersion
+      withStore $ \st -> createRatchetX3dhKeys st connId' pk1 pk2
+      pure (connId', CRInvitationUri crData $ toVersionRangeT e2eRcvParams CR.e2eEncryptVRange)
+
+joinConn :: AgentMonad m => AgentClient -> ConnId -> ConnectionRequestUri c -> ConnInfo -> m ConnId
+joinConn c connId (CRInvitationUri (ConnReqUriData _ agentVRange (qUri :| _)) e2eRcvParamsUri) cInfo =
+  case ( qUri `compatibleVersion` SMP.smpClientVRange,
+         e2eRcvParamsUri `compatibleVersion` CR.e2eEncryptVRange,
+         agentVRange `compatibleVersion` smpAgentVRange
+       ) of
+    (Just qInfo, Just (Compatible e2eRcvParams@(CR.E2ERatchetParams _ _ rcDHRr)), Just _) -> do
+      -- TODO in agent v2 - use found compatible version rather than current
+      (pk1, pk2, e2eSndParams) <- liftIO . CR.generateE2EParams $ version e2eRcvParams
+      (_, rcDHRs) <- liftIO C.generateKeyPair'
+      let rc = CR.initSndRatchet rcDHRr rcDHRs $ CR.x3dhSnd pk1 pk2 e2eRcvParams
+      sq <- newSndQueue qInfo
+      g <- asks idsDrg
+      let cData = ConnData {connId}
+      connId' <- withStore $ \st -> do
+        connId' <- createSndConn st g cData sq
+        createRatchet st connId' rc
+        pure connId'
+      tryError (confirmQueue c connId' sq cInfo $ Just e2eSndParams) >>= \case
+        Right _ -> do
+          void $ enqueueMessage c connId' sq HELLO
+          pure connId'
+        Left e -> do
+          -- TODO recovery for failure on network timeout, see rfcs/2022-04-20-smp-conf-timeout-recovery.md
+          withStore (`deleteConn` connId')
+          throwError e
+    _ -> throwError $ AGENT A_VERSION
+joinConn c connId (CRContactUri (ConnReqUriData _ agentVRange (qUri :| _))) cInfo =
+  case ( qUri `compatibleVersion` SMP.smpClientVRange,
+         agentVRange `compatibleVersion` smpAgentVRange
+       ) of
+    (Just qInfo, Just _) -> do
+      -- TODO in agent v2 - use found compatible version rather than current
+      (connId', cReq) <- newConn c connId SCMInvitation
+      sendInvitation c qInfo cReq cInfo
+      pure connId'
+    _ -> throwError $ AGENT A_VERSION
+
+createReplyQueue :: AgentMonad m => AgentClient -> ConnId -> SndQueue -> m ()
+createReplyQueue c connId sq = do
+  srv <- getSMPServer c
+  (rq, qUri) <- newRcvQueue c srv
+  -- TODO reply queue version should be the same as send queue, ignoring it in v1
+  let qInfo = toVersionT qUri SMP.smpClientVersion
+  addSubscription c rq connId
+  withStore $ \st -> upgradeSndConnToDuplex st connId rq
+  void . enqueueMessage c connId sq $ REPLY [qInfo]
+
+-- | Approve confirmation (LET command) in Reader monad
+allowConnection' :: AgentMonad m => AgentClient -> ConnId -> ConfirmationId -> ConnInfo -> m ()
+allowConnection' c connId confId ownConnInfo = do
+  withStore (`getConn` connId) >>= \case
+    SomeConn _ (RcvConnection _ rq) -> do
+      AcceptedConfirmation {senderConf, ratchetState} <- withStore $ \st -> acceptConfirmation st confId ownConnInfo
+      withStore $ \st -> createRatchet st connId ratchetState
+      processConfirmation c rq senderConf
+    _ -> throwError $ CMD PROHIBITED
+
+-- | Accept contact (ACPT command) in Reader monad
+acceptContact' :: AgentMonad m => AgentClient -> ConnId -> InvitationId -> ConnInfo -> m ConnId
+acceptContact' c connId invId ownConnInfo = do
+  Invitation {contactConnId, connReq} <- withStore (`getInvitation` invId)
+  withStore (`getConn` contactConnId) >>= \case
+    SomeConn _ ContactConnection {} -> do
+      withStore $ \st -> acceptInvitation st invId ownConnInfo
+      joinConn c connId connReq ownConnInfo
+    _ -> throwError $ CMD PROHIBITED
+
+-- | Reject contact (RJCT command) in Reader monad
+rejectContact' :: AgentMonad m => AgentClient -> ConnId -> InvitationId -> m ()
+rejectContact' _ contactConnId invId =
+  withStore $ \st -> deleteInvitation st contactConnId invId
+
+processConfirmation :: AgentMonad m => AgentClient -> RcvQueue -> SMPConfirmation -> m ()
+processConfirmation c rq@RcvQueue {e2ePrivKey} SMPConfirmation {senderKey, e2ePubKey} = do
+  let dhSecret = C.dh' e2ePubKey e2ePrivKey
+  withStore $ \st -> setRcvQueueConfirmedE2E st rq dhSecret
+  secureQueue c rq senderKey
+  withStore $ \st -> setRcvQueueStatus st rq Secured
+
+-- | Subscribe to receive connection messages (SUB command) in Reader monad
+subscribeConnection' :: forall m. AgentMonad m => AgentClient -> ConnId -> m ()
+subscribeConnection' c connId =
+  withStore (`getConn` connId) >>= \case
+    SomeConn _ (DuplexConnection _ rq sq) -> do
+      resumeMsgDelivery c connId sq
+      subscribeQueue c rq connId
+    SomeConn _ (SndConnection _ sq) -> do
+      resumeMsgDelivery c connId sq
+      case status (sq :: SndQueue) of
+        Confirmed -> pure ()
+        Active -> throwError $ CONN SIMPLEX
+        _ -> throwError $ INTERNAL "unexpected queue status"
+    SomeConn _ (RcvConnection _ rq) -> subscribeQueue c rq connId
+    SomeConn _ (ContactConnection _ rq) -> subscribeQueue c rq connId
+
+resubscribeConnection' :: forall m. AgentMonad m => AgentClient -> ConnId -> m ()
+resubscribeConnection' c connId =
+  unlessM
+    (atomically $ hasActiveSubscription c connId)
+    (subscribeConnection' c connId)
+
+-- | Send message to the connection (SEND command) in Reader monad
+sendMessage' :: forall m. AgentMonad m => AgentClient -> ConnId -> MsgBody -> m AgentMsgId
+sendMessage' c connId msg =
+  withStore (`getConn` connId) >>= \case
+    SomeConn _ (DuplexConnection _ _ sq) -> enqueueMsg sq
+    SomeConn _ (SndConnection _ sq) -> enqueueMsg sq
+    _ -> throwError $ CONN SIMPLEX
+  where
+    enqueueMsg :: SndQueue -> m AgentMsgId
+    enqueueMsg sq = enqueueMessage c connId sq $ A_MSG msg
+
+enqueueMessage :: forall m. AgentMonad m => AgentClient -> ConnId -> SndQueue -> AMessage -> m AgentMsgId
+enqueueMessage c connId sq aMessage = do
+  resumeMsgDelivery c connId sq
+  msgId <- storeSentMsg
+  queuePendingMsgs c connId sq [msgId]
+  pure $ unId msgId
+  where
+    storeSentMsg :: m InternalId
+    storeSentMsg = do
+      internalTs <- liftIO getCurrentTime
+      (internalId, internalSndId, prevMsgHash) <- withStore (`updateSndIds` connId)
+      let privHeader = APrivHeader (unSndId internalSndId) prevMsgHash
+          agentMsg = AgentMessage privHeader aMessage
+          agentMsgStr = smpEncode agentMsg
+          internalHash = C.sha256Hash agentMsgStr
+      encAgentMessage <- agentRatchetEncrypt connId agentMsgStr e2eEncUserMsgLength
+      let msgBody = smpEncode $ AgentMsgEnvelope {agentVersion = smpAgentVersion, encAgentMessage}
+          msgType = agentMessageType agentMsg
+          msgData = SndMsgData {internalId, internalSndId, internalTs, msgType, msgBody, internalHash, prevMsgHash}
+      withStore $ \st -> createSndMsg st connId msgData
+      pure internalId
+
+resumeMsgDelivery :: forall m. AgentMonad m => AgentClient -> ConnId -> SndQueue -> m ()
+resumeMsgDelivery c connId sq@SndQueue {server, sndId} = do
+  let qKey = (connId, server, sndId)
+  unlessM (queueDelivering qKey) $
+    async (runSmpQueueMsgDelivery c connId sq)
+      >>= \a -> atomically (TM.insert qKey a $ smpQueueMsgDeliveries c)
+  unlessM connQueued $
+    withStore (`getPendingMsgs` connId)
+      >>= queuePendingMsgs c connId sq
+  where
+    queueDelivering qKey = atomically $ TM.member qKey (smpQueueMsgDeliveries c)
+    connQueued = atomically $ isJust <$> TM.lookupInsert connId True (connMsgsQueued c)
+
+queuePendingMsgs :: AgentMonad m => AgentClient -> ConnId -> SndQueue -> [InternalId] -> m ()
+queuePendingMsgs c connId sq msgIds = atomically $ do
+  q <- getPendingMsgQ c connId sq
+  mapM_ (writeTQueue q) msgIds
+
+getPendingMsgQ :: AgentClient -> ConnId -> SndQueue -> STM (TQueue InternalId)
+getPendingMsgQ c connId SndQueue {server, sndId} = do
+  let qKey = (connId, server, sndId)
+  maybe (newMsgQueue qKey) pure =<< TM.lookup qKey (smpQueueMsgQueues c)
+  where
+    newMsgQueue qKey = do
+      mq <- newTQueue
+      TM.insert qKey mq $ smpQueueMsgQueues c
+      pure mq
+
+runSmpQueueMsgDelivery :: forall m. AgentMonad m => AgentClient -> ConnId -> SndQueue -> m ()
+runSmpQueueMsgDelivery c@AgentClient {subQ} connId sq = do
+  mq <- atomically $ getPendingMsgQ c connId sq
+  ri <- asks $ reconnectInterval . config
+  forever $ do
+    msgId <- atomically $ readTQueue mq
+    let mId = unId msgId
+    withStore (\st -> E.try $ getPendingMsgData st connId msgId) >>= \case
+      Left (e :: E.SomeException) ->
+        notify $ MERR mId (INTERNAL $ show e)
+      Right (rq_, (msgType, msgBody, internalTs)) ->
+        withRetryInterval ri $ \loop ->
+          tryError (send msgType c sq msgBody) >>= \case
+            Left e -> do
+              let err = if msgType == AM_CONN_INFO then ERR e else MERR mId e
+              case e of
+                SMP SMP.QUOTA -> case msgType of
+                  AM_CONN_INFO -> connError msgId NOT_AVAILABLE
+                  _ -> loop
+                SMP SMP.AUTH -> case msgType of
+                  AM_CONN_INFO -> connError msgId NOT_AVAILABLE
+                  AM_HELLO_ -> do
+                    helloTimeout <- asks $ helloTimeout . config
+                    currentTime <- liftIO getCurrentTime
+                    if diffUTCTime currentTime internalTs > helloTimeout
+                      then case rq_ of
+                        -- party initiating connection
+                        Just _ -> connError msgId NOT_AVAILABLE
+                        -- party joining connection
+                        _ -> connError msgId NOT_ACCEPTED
+                      else loop
+                  AM_REPLY_ -> notifyDel msgId $ ERR e
+                  AM_A_MSG_ -> notifyDel msgId $ MERR mId e
+                SMP (SMP.CMD _) -> notifyDel msgId err
+                SMP SMP.LARGE_MSG -> notifyDel msgId err
+                SMP {} -> notify err >> loop
+                _ -> loop
+            Right () -> do
+              case msgType of
+                AM_CONN_INFO -> do
+                  withStore $ \st -> setSndQueueStatus st sq Confirmed
+                  when (isJust rq_) $ withStore (`removeConfirmations` connId)
+                  void $ enqueueMessage c connId sq HELLO
+                AM_HELLO_ -> do
+                  withStore $ \st -> setSndQueueStatus st sq Active
+                  case rq_ of
+                    -- party initiating connection
+                    Just rq -> do
+                      subscribeQueue c rq connId
+                      notify CON
+                    -- party joining connection
+                    _ -> createReplyQueue c connId sq
+                AM_A_MSG_ -> notify $ SENT mId
+                _ -> pure ()
+              delMsg msgId
+  where
+    send = \case
+      AM_CONN_INFO -> sendConfirmation
+      _ -> sendAgentMessage
+    delMsg :: InternalId -> m ()
+    delMsg msgId = withStore $ \st -> deleteMsg st connId msgId
+    notify :: ACommand 'Agent -> m ()
+    notify cmd = atomically $ writeTBQueue subQ ("", connId, cmd)
+    notifyDel :: InternalId -> ACommand 'Agent -> m ()
+    notifyDel msgId cmd = notify cmd >> delMsg msgId
+    connError msgId = notifyDel msgId . ERR . CONN
+
+ackMessage' :: forall m. AgentMonad m => AgentClient -> ConnId -> AgentMsgId -> m ()
+ackMessage' c connId msgId = do
+  withStore (`getConn` connId) >>= \case
+    SomeConn _ (DuplexConnection _ rq _) -> ack rq
+    SomeConn _ (RcvConnection _ rq) -> ack rq
+    _ -> throwError $ CONN SIMPLEX
+  where
+    ack :: RcvQueue -> m ()
+    ack rq = do
+      let mId = InternalId msgId
+      withStore $ \st -> checkRcvMsg st connId mId
+      sendAck c rq
+      withStore $ \st -> deleteMsg st connId mId
+
+-- | Suspend SMP agent connection (OFF command) in Reader monad
+suspendConnection' :: AgentMonad m => AgentClient -> ConnId -> m ()
+suspendConnection' c connId =
+  withStore (`getConn` connId) >>= \case
+    SomeConn _ (DuplexConnection _ rq _) -> suspendQueue c rq
+    SomeConn _ (RcvConnection _ rq) -> suspendQueue c rq
+    _ -> throwError $ CONN SIMPLEX
+
+-- | Delete SMP agent connection (DEL command) in Reader monad
+deleteConnection' :: forall m. AgentMonad m => AgentClient -> ConnId -> m ()
+deleteConnection' c connId =
+  withStore (`getConn` connId) >>= \case
+    SomeConn _ (DuplexConnection _ rq _) -> delete rq
+    SomeConn _ (RcvConnection _ rq) -> delete rq
+    SomeConn _ (ContactConnection _ rq) -> delete rq
+    SomeConn _ (SndConnection _ _) -> withStore (`deleteConn` connId)
+  where
+    delete :: RcvQueue -> m ()
+    delete rq = do
+      deleteQueue c rq
+      atomically $ removeSubscription c connId
+      withStore (`deleteConn` connId)
+
+-- | Change servers to be used for creating new queues, in Reader monad
+setSMPServers' :: AgentMonad m => AgentClient -> NonEmpty SMPServer -> m ()
+setSMPServers' c servers = do
+  atomically $ writeTVar (smpServers c) servers
+
+registerNtfToken' :: forall m. AgentMonad m => AgentClient -> DeviceToken -> m NtfTknStatus
+registerNtfToken' c deviceToken =
+  withStore (`getDeviceNtfToken` deviceToken) >>= \case
+    (Just tkn@NtfToken {ntfTokenId, ntfTknStatus, ntfTknAction}, prevTokens) -> do
+      mapM_ (deleteToken_ c) prevTokens
+      case (ntfTokenId, ntfTknAction) of
+        (Nothing, Just NTARegister) -> registerToken tkn $> NTRegistered
+        -- TODO minimal time before repeat registration
+        (Just _, Nothing) -> when (ntfTknStatus == NTRegistered) (registerToken tkn) $> NTRegistered
+        (Just tknId, Just (NTAVerify code)) ->
+          t tkn (NTActive, Just NTACheck) $ agentNtfVerifyToken c tknId tkn code
+        (Just tknId, Just (NTACron interval)) ->
+          t tkn (cronSuccess interval) $ agentNtfEnableCron c tknId tkn interval
+        (Just _tknId, Just NTACheck) -> pure ntfTknStatus -- TODO
+        -- agentNtfCheckToken c tknId tkn >>= \case
+        (Just tknId, Just NTADelete) -> do
+          agentNtfDeleteToken c tknId tkn
+          withStore $ \st -> removeNtfToken st tkn $> NTExpired
+        _ -> pure ntfTknStatus
+    _ ->
+      getNtfServer c >>= \case
+        Just ntfServer ->
+          asks (cmdSignAlg . config) >>= \case
+            C.SignAlg a -> do
+              tknKeys <- liftIO $ C.generateSignatureKeyPair a
+              dhKeys <- liftIO C.generateKeyPair'
+              let tkn = newNtfToken deviceToken ntfServer tknKeys dhKeys
+              withStore $ \st -> createNtfToken st tkn
+              registerToken tkn
+              pure NTRegistered
+        _ -> throwError $ CMD PROHIBITED
+  where
+    t tkn = withToken c tkn Nothing
+    registerToken :: NtfToken -> m ()
+    registerToken tkn@NtfToken {ntfPubKey, ntfDhKeys = (pubDhKey, privDhKey)} = do
+      (tknId, srvPubDhKey) <- agentNtfRegisterToken c tkn ntfPubKey pubDhKey
+      let dhSecret = C.dh' srvPubDhKey privDhKey
+      withStore $ \st -> updateNtfTokenRegistration st tkn tknId dhSecret
+
+-- TODO decrypt verification code
+verifyNtfToken' :: AgentMonad m => AgentClient -> DeviceToken -> ByteString -> C.CbNonce -> m ()
+verifyNtfToken' c deviceToken code nonce =
+  withStore (`getDeviceNtfToken` deviceToken) >>= \case
+    (Just tkn@NtfToken {ntfTokenId = Just tknId, ntfDhSecret = Just dhSecret}, _) -> do
+      code' <- liftEither . bimap cryptoError NtfRegCode $ C.cbDecrypt dhSecret nonce code
+      void . withToken c tkn (Just (NTConfirmed, NTAVerify code')) (NTActive, Just NTACheck) $
+        agentNtfVerifyToken c tknId tkn code'
+    _ -> throwError $ CMD PROHIBITED
+
+enableNtfCron' :: AgentMonad m => AgentClient -> DeviceToken -> Word16 -> m ()
+enableNtfCron' c deviceToken interval = do
+  when (interval < 20) . throwError $ CMD PROHIBITED
+  withStore (`getDeviceNtfToken` deviceToken) >>= \case
+    (Just tkn@NtfToken {ntfTokenId = Just tknId, ntfTknStatus = NTActive}, _) ->
+      void . withToken c tkn (Just (NTActive, NTACron interval)) (cronSuccess interval) $
+        agentNtfEnableCron c tknId tkn interval
+    _ -> throwError $ CMD PROHIBITED
+
+cronSuccess :: Word16 -> (NtfTknStatus, Maybe NtfTknAction)
+cronSuccess interval
+  | interval == 0 = (NTActive, Just NTACheck)
+  | otherwise = (NTActive, Just $ NTACron interval)
+
+checkNtfToken' :: AgentMonad m => AgentClient -> DeviceToken -> m NtfTknStatus
+checkNtfToken' c deviceToken =
+  withStore (`getDeviceNtfToken` deviceToken) >>= \case
+    (Just tkn@NtfToken {ntfTokenId = Just tknId}, _) -> agentNtfCheckToken c tknId tkn
+    _ -> throwError $ CMD PROHIBITED
+
+deleteNtfToken' :: AgentMonad m => AgentClient -> DeviceToken -> m ()
+deleteNtfToken' c deviceToken =
+  withStore (`getDeviceNtfToken` deviceToken) >>= \case
+    (Just tkn, _) -> deleteToken_ c tkn
+    _ -> throwError $ CMD PROHIBITED
+
+deleteToken_ :: AgentMonad m => AgentClient -> NtfToken -> m ()
+deleteToken_ c tkn@NtfToken {ntfTokenId, ntfTknStatus} = do
+  forM_ ntfTokenId $ \tknId -> do
+    withStore $ \st -> updateNtfToken st tkn ntfTknStatus (Just NTADelete)
+    agentNtfDeleteToken c tknId tkn `catchError` \case
+      NTF AUTH -> pure ()
+      e -> throwError e
+  withStore $ \st -> removeNtfToken st tkn
+
+withToken :: AgentMonad m => AgentClient -> NtfToken -> Maybe (NtfTknStatus, NtfTknAction) -> (NtfTknStatus, Maybe NtfTknAction) -> m a -> m NtfTknStatus
+withToken c tkn@NtfToken {deviceToken} from_ (toStatus, toAction_) f = do
+  forM_ from_ $ \(status, action) -> withStore $ \st -> updateNtfToken st tkn status (Just action)
+  tryError f >>= \case
+    Right _ -> do
+      withStore $ \st -> updateNtfToken st tkn toStatus toAction_
+      pure toStatus
+    Left e@(NTF AUTH) -> do
+      withStore $ \st -> removeNtfToken st tkn
+      void $ registerNtfToken' c deviceToken
+      throwError e
+    Left e -> throwError e
+
+setNtfServers' :: AgentMonad m => AgentClient -> [NtfServer] -> m ()
+setNtfServers' c servers = do
+  atomically $ writeTVar (ntfServers c) servers
+
+getSMPServer :: AgentMonad m => AgentClient -> m SMPServer
+getSMPServer c = do
+  smpServers <- readTVarIO $ smpServers c
+  case smpServers of
+    srv :| [] -> pure srv
+    servers -> do
+      gen <- asks randomServer
+      atomically . stateTVar gen $
+        first (servers L.!!) . randomR (0, L.length servers - 1)
+
+getNtfServer :: AgentMonad m => AgentClient -> m (Maybe NtfServer)
+getNtfServer c = do
+  ntfServers <- readTVarIO $ ntfServers c
+  case ntfServers of
+    [] -> pure Nothing
+    [srv] -> pure $ Just srv
+    servers -> do
+      gen <- asks randomServer
+      atomically . stateTVar gen $
+        first (Just . (servers !!)) . randomR (0, length servers - 1)
+
+subscriber :: (MonadUnliftIO m, MonadReader Env m) => AgentClient -> m ()
+subscriber c@AgentClient {msgQ} = forever $ do
+  t <- atomically $ readTBQueue msgQ
+  withAgentLock c (runExceptT $ processSMPTransmission c t) >>= \case
+    Left e -> liftIO $ print e
+    Right _ -> return ()
+
+processSMPTransmission :: forall m. AgentMonad m => AgentClient -> ServerTransmission BrokerMsg -> m ()
+processSMPTransmission c@AgentClient {smpClients, subQ} (srv, sessId, rId, cmd) = do
+  withStore (\st -> getRcvConn st srv rId) >>= \case
+    SomeConn SCDuplex (DuplexConnection cData rq _) -> processSMP SCDuplex cData rq
+    SomeConn SCRcv (RcvConnection cData rq) -> processSMP SCRcv cData rq
+    SomeConn SCContact (ContactConnection cData rq) -> processSMP SCContact cData rq
+    _ -> atomically $ writeTBQueue subQ ("", "", ERR $ CONN NOT_FOUND)
+  where
+    processSMP :: SConnType c -> ConnData -> RcvQueue -> m ()
+    processSMP cType ConnData {connId} rq@RcvQueue {rcvDhSecret, e2ePrivKey, e2eDhSecret, status} =
+      case cmd of
+        SMP.MSG srvMsgId srvTs msgBody' -> handleNotifyAck $ do
+          -- TODO deduplicate with previously received
+          msgBody <- agentCbDecrypt rcvDhSecret (C.cbNonce srvMsgId) msgBody'
+          clientMsg@SMP.ClientMsgEnvelope {cmHeader = SMP.PubHeader phVer e2ePubKey_} <-
+            parseMessage msgBody
+          unless (phVer `isCompatible` SMP.smpClientVRange) . throwError $ AGENT A_VERSION
+          case (e2eDhSecret, e2ePubKey_) of
+            (Nothing, Just e2ePubKey) -> do
+              let e2eDh = C.dh' e2ePubKey e2ePrivKey
+              decryptClientMessage e2eDh clientMsg >>= \case
+                (SMP.PHConfirmation senderKey, AgentConfirmation {e2eEncryption, encConnInfo}) ->
+                  smpConfirmation senderKey e2ePubKey e2eEncryption encConnInfo >> ack
+                (SMP.PHEmpty, AgentInvitation {connReq, connInfo}) ->
+                  smpInvitation connReq connInfo >> ack
+                _ -> prohibited >> ack
+            (Just e2eDh, Nothing) -> do
+              decryptClientMessage e2eDh clientMsg >>= \case
+                (SMP.PHEmpty, AgentMsgEnvelope _ encAgentMsg) -> do
+                  agentMsgBody <- agentRatchetDecrypt connId encAgentMsg
+                  parseMessage agentMsgBody >>= \case
+                    agentMsg@(AgentMessage APrivHeader {sndMsgId, prevMsgHash} aMessage) -> do
+                      let msgType = agentMessageType agentMsg
+                      (msgId, msgMeta) <- agentClientMsg prevMsgHash sndMsgId (srvMsgId, systemToUTCTime srvTs) agentMsgBody msgType
+                      case aMessage of
+                        HELLO -> helloMsg >> ack >> withStore (\st -> deleteMsg st connId msgId)
+                        REPLY cReq -> replyMsg cReq >> ack >> withStore (\st -> deleteMsg st connId msgId)
+                        -- note that there is no ACK sent here, it is sent with agent's user ACK command
+                        A_MSG body -> notify $ MSG msgMeta body
+                    _ -> prohibited >> ack
+                _ -> prohibited >> ack
+            _ -> prohibited >> ack
+        SMP.END ->
+          atomically (TM.lookup srv smpClients $>>= tryReadTMVar >>= processEND)
+            >>= logServer "<--" c srv rId
+          where
+            processEND = \case
+              Just (Right clnt)
+                | sessId == sessionId clnt -> do
+                  removeSubscription c connId
+                  writeTBQueue subQ ("", connId, END)
+                  pure "END"
+                | otherwise -> ignored
+              _ -> ignored
+            ignored = pure "END from disconnected client - ignored"
+        _ -> do
+          logServer "<--" c srv rId $ "unexpected: " <> bshow cmd
+          notify . ERR $ BROKER UNEXPECTED
+      where
+        notify :: ACommand 'Agent -> m ()
+        notify msg = atomically $ writeTBQueue subQ ("", connId, msg)
+
+        handleNotifyAck :: m () -> m ()
+        handleNotifyAck m = m `catchError` \e -> notify (ERR e) >> ack
+
+        prohibited :: m ()
+        prohibited = notify . ERR $ AGENT A_PROHIBITED
+
+        ack :: m ()
+        ack = sendAck c rq
+
+        decryptClientMessage :: C.DhSecretX25519 -> SMP.ClientMsgEnvelope -> m (SMP.PrivHeader, AgentMsgEnvelope)
+        decryptClientMessage e2eDh SMP.ClientMsgEnvelope {cmNonce, cmEncBody} = do
+          clientMsg <- agentCbDecrypt e2eDh cmNonce cmEncBody
+          SMP.ClientMessage privHeader clientBody <- parseMessage clientMsg
+          agentEnvelope <- parseMessage clientBody
+          if agentVersion agentEnvelope `isCompatible` smpAgentVRange
+            then pure (privHeader, agentEnvelope)
+            else throwError $ AGENT A_VERSION
+
+        parseMessage :: Encoding a => ByteString -> m a
+        parseMessage = liftEither . parse smpP (AGENT A_MESSAGE)
+
+        smpConfirmation :: C.APublicVerifyKey -> C.PublicKeyX25519 -> Maybe (CR.E2ERatchetParams 'C.X448) -> ByteString -> m ()
+        smpConfirmation senderKey e2ePubKey e2eEncryption encConnInfo = do
+          logServer "<--" c srv rId "MSG <CONF>"
+          case status of
+            New -> case (cType, e2eEncryption) of
+              (SCRcv, Just e2eSndParams) -> do
+                (pk1, rcDHRs) <- withStore $ \st -> getRatchetX3dhKeys st connId
+                let rc = CR.initRcvRatchet rcDHRs $ CR.x3dhRcv pk1 rcDHRs e2eSndParams
+                (agentMsgBody_, rc', skipped) <- liftError cryptoError $ CR.rcDecrypt rc M.empty encConnInfo
+                case (agentMsgBody_, skipped) of
+                  (Right agentMsgBody, CR.SMDNoChange) ->
+                    parseMessage agentMsgBody >>= \case
+                      AgentConnInfo connInfo -> do
+                        g <- asks idsDrg
+                        let senderConf = SMPConfirmation {senderKey, e2ePubKey, connInfo}
+                            newConfirmation = NewConfirmation {connId, senderConf, ratchetState = rc'}
+                        confId <- withStore $ \st -> createConfirmation st g newConfirmation
+                        notify $ CONF confId connInfo
+                      _ -> prohibited
+                  _ -> prohibited
+              (SCDuplex, Nothing) -> do
+                agentRatchetDecrypt connId encConnInfo >>= parseMessage >>= \case
+                  AgentConnInfo connInfo -> do
+                    notify $ INFO connInfo
+                    processConfirmation c rq $ SMPConfirmation {senderKey, e2ePubKey, connInfo}
+                  _ -> prohibited
+              _ -> prohibited
+            _ -> prohibited
+
+        helloMsg :: m ()
+        helloMsg = do
+          logServer "<--" c srv rId "MSG <HELLO>"
+          case status of
+            Active -> prohibited
+            _ -> do
+              withStore $ \st -> setRcvQueueStatus st rq Active
+              case cType of
+                SCDuplex -> notifyConnected c connId
+                _ -> pure ()
+
+        replyMsg :: L.NonEmpty SMPQueueInfo -> m ()
+        replyMsg (qInfo :| _) = do
+          logServer "<--" c srv rId "MSG <REPLY>"
+          case cType of
+            SCRcv -> do
+              AcceptedConfirmation {ownConnInfo} <- withStore (`getAcceptedConfirmation` connId)
+              case qInfo `proveCompatible` SMP.smpClientVRange of
+                Nothing -> notify . ERR $ AGENT A_VERSION
+                Just qInfo' -> do
+                  sq <- newSndQueue qInfo'
+                  withStore $ \st -> upgradeRcvConnToDuplex st connId sq
+                  enqueueConfirmation c connId sq ownConnInfo Nothing
+            _ -> prohibited
+
+        agentClientMsg :: PrevRcvMsgHash -> ExternalSndId -> (BrokerId, BrokerTs) -> MsgBody -> AgentMessageType -> m (InternalId, MsgMeta)
+        agentClientMsg externalPrevSndHash sndMsgId broker msgBody msgType = do
+          logServer "<--" c srv rId "MSG <MSG>"
+          let internalHash = C.sha256Hash msgBody
+          internalTs <- liftIO getCurrentTime
+          (internalId, internalRcvId, prevExtSndId, prevRcvMsgHash) <- withStore (`updateRcvIds` connId)
+          let integrity = checkMsgIntegrity prevExtSndId sndMsgId prevRcvMsgHash externalPrevSndHash
+              recipient = (unId internalId, internalTs)
+              msgMeta = MsgMeta {integrity, recipient, broker, sndMsgId}
+              rcvMsg = RcvMsgData {msgMeta, msgType, msgBody, internalRcvId, internalHash, externalPrevSndHash}
+          withStore $ \st -> createRcvMsg st connId rcvMsg
+          pure (internalId, msgMeta)
+
+        smpInvitation :: ConnectionRequestUri 'CMInvitation -> ConnInfo -> m ()
+        smpInvitation connReq cInfo = do
+          logServer "<--" c srv rId "MSG <KEY>"
+          case cType of
+            SCContact -> do
+              g <- asks idsDrg
+              let newInv = NewInvitation {contactConnId = connId, connReq, recipientConnInfo = cInfo}
+              invId <- withStore $ \st -> createInvitation st g newInv
+              notify $ REQ invId cInfo
+            _ -> prohibited
+
+        checkMsgIntegrity :: PrevExternalSndId -> ExternalSndId -> PrevRcvMsgHash -> ByteString -> MsgIntegrity
+        checkMsgIntegrity prevExtSndId extSndId internalPrevMsgHash receivedPrevMsgHash
+          | extSndId == prevExtSndId + 1 && internalPrevMsgHash == receivedPrevMsgHash = MsgOk
+          | extSndId < prevExtSndId = MsgError $ MsgBadId extSndId
+          | extSndId == prevExtSndId = MsgError MsgDuplicate -- ? deduplicate
+          | extSndId > prevExtSndId + 1 = MsgError $ MsgSkipped (prevExtSndId + 1) (extSndId - 1)
+          | internalPrevMsgHash /= receivedPrevMsgHash = MsgError MsgBadHash
+          | otherwise = MsgError MsgDuplicate -- this case is not possible
+
+confirmQueue :: forall m. AgentMonad m => AgentClient -> ConnId -> SndQueue -> ConnInfo -> Maybe (CR.E2ERatchetParams 'C.X448) -> m ()
+confirmQueue c connId sq connInfo e2eEncryption = do
+  _ <- withStore (`updateSndIds` connId)
+  msg <- mkConfirmation
+  sendConfirmation c sq msg
+  withStore $ \st -> setSndQueueStatus st sq Confirmed
+  where
+    mkConfirmation :: m MsgBody
+    mkConfirmation = do
+      encConnInfo <- agentRatchetEncrypt connId (smpEncode $ AgentConnInfo connInfo) e2eEncConnInfoLength
+      pure . smpEncode $ AgentConfirmation {agentVersion = smpAgentVersion, e2eEncryption, encConnInfo}
+
+enqueueConfirmation :: forall m. AgentMonad m => AgentClient -> ConnId -> SndQueue -> ConnInfo -> Maybe (CR.E2ERatchetParams 'C.X448) -> m ()
+enqueueConfirmation c connId sq connInfo e2eEncryption = do
+  resumeMsgDelivery c connId sq
+  msgId <- storeConfirmation
+  queuePendingMsgs c connId sq [msgId]
+  where
+    storeConfirmation :: m InternalId
+    storeConfirmation = do
+      internalTs <- liftIO getCurrentTime
+      (internalId, internalSndId, prevMsgHash) <- withStore (`updateSndIds` connId)
+      let agentMsg = AgentConnInfo connInfo
+          agentMsgStr = smpEncode agentMsg
+          internalHash = C.sha256Hash agentMsgStr
+      encConnInfo <- agentRatchetEncrypt connId agentMsgStr e2eEncConnInfoLength
+      let msgBody = smpEncode $ AgentConfirmation {agentVersion = smpAgentVersion, e2eEncryption, encConnInfo}
+          msgType = agentMessageType agentMsg
+          msgData = SndMsgData {internalId, internalSndId, internalTs, msgType, msgBody, internalHash, prevMsgHash}
+      withStore $ \st -> createSndMsg st connId msgData
+      pure internalId
+
+-- encoded AgentMessage -> encoded EncAgentMessage
+agentRatchetEncrypt :: AgentMonad m => ConnId -> ByteString -> Int -> m ByteString
+agentRatchetEncrypt connId msg paddedLen = do
+  rc <- withStore $ \st -> getRatchet st connId
+  (encMsg, rc') <- liftError cryptoError $ CR.rcEncrypt rc paddedLen msg
+  withStore $ \st -> updateRatchet st connId rc' CR.SMDNoChange
+  pure encMsg
+
+-- encoded EncAgentMessage -> encoded AgentMessage
+agentRatchetDecrypt :: AgentMonad m => ConnId -> ByteString -> m ByteString
+agentRatchetDecrypt connId encAgentMsg = do
+  (rc, skipped) <- withStore $ \st ->
+    (,) <$> getRatchet st connId <*> getSkippedMsgKeys st connId
+  (agentMsgBody_, rc', skippedDiff) <- liftError cryptoError $ CR.rcDecrypt rc skipped encAgentMsg
+  withStore $ \st -> updateRatchet st connId rc' skippedDiff
+  liftEither $ first cryptoError agentMsgBody_
+
+notifyConnected :: AgentMonad m => AgentClient -> ConnId -> m ()
+notifyConnected c connId = atomically $ writeTBQueue (subQ c) ("", connId, CON)
+
+newSndQueue :: (MonadUnliftIO m, MonadReader Env m) => Compatible SMPQueueInfo -> m SndQueue
+newSndQueue qInfo =
+  asks (cmdSignAlg . config) >>= \case
+    C.SignAlg a -> newSndQueue_ a qInfo
+
+newSndQueue_ ::
+  (C.SignatureAlgorithm a, C.AlgorithmI a, MonadUnliftIO m) =>
+  C.SAlgorithm a ->
+  Compatible SMPQueueInfo ->
+  m SndQueue
+newSndQueue_ a (Compatible (SMPQueueInfo _clientVersion smpServer senderId rcvE2ePubDhKey)) = do
+  -- this function assumes clientVersion is compatible - it was tested before
+  (sndPublicKey, sndPrivateKey) <- liftIO $ C.generateSignatureKeyPair a
+  (e2ePubKey, e2ePrivKey) <- liftIO C.generateKeyPair'
+  pure
+    SndQueue
+      { server = smpServer,
+        sndId = senderId,
+        sndPublicKey = Just sndPublicKey,
+        sndPrivateKey,
+        e2eDhSecret = C.dh' rcvE2ePubDhKey e2ePrivKey,
+        e2ePubKey = Just e2ePubKey,
+        status = New
+      }

src/Simplex/Messaging/Agent/Client.hs

@@ -0,0 +1,568 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedLists #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+
+module Simplex.Messaging.Agent.Client
+  ( AgentClient (..),
+    newAgentClient,
+    AgentMonad,
+    withAgentLock,
+    closeAgentClient,
+    newRcvQueue,
+    subscribeQueue,
+    addSubscription,
+    sendConfirmation,
+    sendInvitation,
+    RetryInterval (..),
+    secureQueue,
+    sendAgentMessage,
+    agentNtfRegisterToken,
+    agentNtfVerifyToken,
+    agentNtfCheckToken,
+    agentNtfDeleteToken,
+    agentNtfEnableCron,
+    agentCbEncrypt,
+    agentCbDecrypt,
+    cryptoError,
+    sendAck,
+    suspendQueue,
+    deleteQueue,
+    logServer,
+    removeSubscription,
+    hasActiveSubscription,
+    agentDbPath,
+  )
+where
+
+import Control.Concurrent (forkIO)
+import Control.Concurrent.Async (Async, uninterruptibleCancel)
+import Control.Concurrent.STM (stateTVar)
+import Control.Logger.Simple
+import Control.Monad.Except
+import Control.Monad.IO.Unlift
+import Control.Monad.Reader
+import Data.Bifunctor (first)
+import Data.ByteString.Base64
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.List.NonEmpty (NonEmpty)
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Maybe (catMaybes)
+import Data.Text.Encoding
+import Data.Word (Word16)
+import Simplex.Messaging.Agent.Env.SQLite
+import Simplex.Messaging.Agent.Protocol
+import Simplex.Messaging.Agent.RetryInterval
+import Simplex.Messaging.Agent.Store
+import Simplex.Messaging.Agent.Store.SQLite (SQLiteStore (..))
+import Simplex.Messaging.Client
+import Simplex.Messaging.Client.Agent ()
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Notifications.Client
+import Simplex.Messaging.Notifications.Protocol
+import Simplex.Messaging.Protocol (BrokerMsg, ErrorType, ProtocolServer (..), QueueId, QueueIdsKeys (..), SndPublicVerifyKey)
+import qualified Simplex.Messaging.Protocol as SMP
+import Simplex.Messaging.TMap (TMap)
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Util (bshow, catchAll_, ifM, liftEitherError, liftError, tryError, unlessM, whenM)
+import Simplex.Messaging.Version
+import System.Timeout (timeout)
+import UnliftIO (async, pooledForConcurrentlyN)
+import qualified UnliftIO.Exception as E
+import UnliftIO.STM
+
+type ClientVar msg = TMVar (Either AgentErrorType (ProtocolClient msg))
+
+type SMPClientVar = TMVar (Either AgentErrorType SMPClient)
+
+type NtfClientVar = TMVar (Either AgentErrorType NtfClient)
+
+data AgentClient = AgentClient
+  { active :: TVar Bool,
+    rcvQ :: TBQueue (ATransmission 'Client),
+    subQ :: TBQueue (ATransmission 'Agent),
+    msgQ :: TBQueue (ServerTransmission BrokerMsg),
+    smpServers :: TVar (NonEmpty SMPServer),
+    ntfServers :: TVar [NtfServer],
+    smpClients :: TMap SMPServer SMPClientVar,
+    ntfClients :: TMap NtfServer NtfClientVar,
+    subscrSrvrs :: TMap SMPServer (TMap ConnId RcvQueue),
+    pendingSubscrSrvrs :: TMap SMPServer (TMap ConnId RcvQueue),
+    subscrConns :: TMap ConnId SMPServer,
+    connMsgsQueued :: TMap ConnId Bool,
+    smpQueueMsgQueues :: TMap (ConnId, SMPServer, SMP.SenderId) (TQueue InternalId),
+    smpQueueMsgDeliveries :: TMap (ConnId, SMPServer, SMP.SenderId) (Async ()),
+    reconnections :: TVar [Async ()],
+    asyncClients :: TVar [Async ()],
+    clientId :: Int,
+    agentEnv :: Env,
+    smpSubscriber :: Async (),
+    lock :: TMVar ()
+  }
+
+newAgentClient :: InitialAgentServers -> Env -> STM AgentClient
+newAgentClient InitialAgentServers {smp, ntf} agentEnv = do
+  let qSize = tbqSize $ config agentEnv
+  active <- newTVar True
+  rcvQ <- newTBQueue qSize
+  subQ <- newTBQueue qSize
+  msgQ <- newTBQueue qSize
+  smpServers <- newTVar smp
+  ntfServers <- newTVar ntf
+  smpClients <- TM.empty
+  ntfClients <- TM.empty
+  subscrSrvrs <- TM.empty
+  pendingSubscrSrvrs <- TM.empty
+  subscrConns <- TM.empty
+  connMsgsQueued <- TM.empty
+  smpQueueMsgQueues <- TM.empty
+  smpQueueMsgDeliveries <- TM.empty
+  reconnections <- newTVar []
+  asyncClients <- newTVar []
+  clientId <- stateTVar (clientCounter agentEnv) $ \i -> (i + 1, i + 1)
+  lock <- newTMVar ()
+  return AgentClient {active, rcvQ, subQ, msgQ, smpServers, ntfServers, smpClients, ntfClients, subscrSrvrs, pendingSubscrSrvrs, subscrConns, connMsgsQueued, smpQueueMsgQueues, smpQueueMsgDeliveries, reconnections, asyncClients, clientId, agentEnv, smpSubscriber = undefined, lock}
+
+agentDbPath :: AgentClient -> FilePath
+agentDbPath AgentClient {agentEnv = Env {store = SQLiteStore {dbFilePath}}} = dbFilePath
+
+-- | Agent monad with MonadReader Env and MonadError AgentErrorType
+type AgentMonad m = (MonadUnliftIO m, MonadReader Env m, MonadError AgentErrorType m)
+
+class ProtocolServerClient msg where
+  getProtocolServerClient :: AgentMonad m => AgentClient -> ProtocolServer -> m (ProtocolClient msg)
+  protocolError :: ErrorType -> AgentErrorType
+
+instance ProtocolServerClient BrokerMsg where
+  getProtocolServerClient = getSMPServerClient
+  protocolError = SMP
+
+instance ProtocolServerClient NtfResponse where
+  getProtocolServerClient = getNtfServerClient
+  protocolError = NTF
+
+getSMPServerClient :: forall m. AgentMonad m => AgentClient -> SMPServer -> m SMPClient
+getSMPServerClient c@AgentClient {active, smpClients, msgQ} srv = do
+  unlessM (readTVarIO active) . throwError $ INTERNAL "agent is stopped"
+  atomically (getClientVar srv smpClients)
+    >>= either
+      (newProtocolClient c srv smpClients connectClient reconnectClient)
+      (waitForProtocolClient smpCfg)
+  where
+    connectClient :: m SMPClient
+    connectClient = do
+      cfg <- asks $ smpCfg . config
+      u <- askUnliftIO
+      liftEitherError (protocolClientError SMP) (getProtocolClient srv cfg (Just msgQ) $ clientDisconnected u)
+
+    clientDisconnected :: UnliftIO m -> IO ()
+    clientDisconnected u = do
+      removeClientAndSubs >>= (`forM_` serverDown u)
+      logInfo . decodeUtf8 $ "Agent disconnected from " <> showServer srv
+
+    removeClientAndSubs :: IO (Maybe (Map ConnId RcvQueue))
+    removeClientAndSubs = atomically $ do
+      TM.delete srv smpClients
+      TM.lookupDelete srv (subscrSrvrs c) >>= mapM updateSubs
+      where
+        updateSubs cVar = do
+          cs <- readTVar cVar
+          modifyTVar' (subscrConns c) (`M.withoutKeys` M.keysSet cs)
+          addPendingSubs cVar cs
+          pure cs
+
+        addPendingSubs cVar cs = do
+          let ps = pendingSubscrSrvrs c
+          TM.lookup srv ps >>= \case
+            Just v -> TM.union cs v
+            _ -> TM.insert srv cVar ps
+
+    serverDown :: UnliftIO m -> Map ConnId RcvQueue -> IO ()
+    serverDown u cs = unless (M.null cs) $
+      whenM (readTVarIO active) $ do
+        let conns = M.keys cs
+        unless (null conns) . notifySub "" $ DOWN srv conns
+        unliftIO u reconnectServer
+
+    reconnectServer :: m ()
+    reconnectServer = do
+      a <- async tryReconnectClient
+      atomically $ modifyTVar' (reconnections c) (a :)
+
+    tryReconnectClient :: m ()
+    tryReconnectClient = do
+      ri <- asks $ reconnectInterval . config
+      withRetryInterval ri $ \loop ->
+        reconnectClient `catchError` const loop
+
+    reconnectClient :: m ()
+    reconnectClient = do
+      n <- asks $ resubscriptionConcurrency . config
+      withAgentLock c . withClient c srv $ \smp -> do
+        cs <- atomically $ mapM readTVar =<< TM.lookup srv (pendingSubscrSrvrs c)
+        conns <- pooledForConcurrentlyN n (maybe [] M.toList cs) $ \sub@(connId, _) ->
+          ifM
+            (atomically $ hasActiveSubscription c connId)
+            (pure $ Just connId)
+            (subscribe_ smp sub `catchError` handleError connId)
+        liftIO . unless (null conns) . notifySub "" . UP srv $ catMaybes conns
+      where
+        subscribe_ :: SMPClient -> (ConnId, RcvQueue) -> ExceptT ProtocolClientError IO (Maybe ConnId)
+        subscribe_ smp (connId, rq@RcvQueue {rcvPrivateKey, rcvId}) = do
+          subscribeSMPQueue smp rcvPrivateKey rcvId
+          addSubscription c rq connId
+          pure $ Just connId
+
+        handleError :: ConnId -> ProtocolClientError -> ExceptT ProtocolClientError IO (Maybe ConnId)
+        handleError connId = \case
+          e@PCEResponseTimeout -> throwError e
+          e@PCENetworkError -> throwError e
+          e -> do
+            liftIO . notifySub connId . ERR $ protocolClientError SMP e
+            atomically $ removePendingSubscription c srv connId
+            pure Nothing
+
+    notifySub :: ConnId -> ACommand 'Agent -> IO ()
+    notifySub connId cmd = atomically $ writeTBQueue (subQ c) ("", connId, cmd)
+
+getNtfServerClient :: forall m. AgentMonad m => AgentClient -> NtfServer -> m NtfClient
+getNtfServerClient c@AgentClient {active, ntfClients} srv = do
+  unlessM (readTVarIO active) . throwError $ INTERNAL "agent is stopped"
+  atomically (getClientVar srv ntfClients)
+    >>= either
+      (newProtocolClient c srv ntfClients connectClient $ pure ())
+      (waitForProtocolClient ntfCfg)
+  where
+    connectClient :: m NtfClient
+    connectClient = do
+      cfg <- asks $ ntfCfg . config
+      liftEitherError (protocolClientError NTF) (getProtocolClient srv cfg Nothing clientDisconnected)
+
+    clientDisconnected :: IO ()
+    clientDisconnected = do
+      atomically $ TM.delete srv ntfClients
+      logInfo . decodeUtf8 $ "Agent disconnected from " <> showServer srv
+
+getClientVar :: forall a. ProtocolServer -> TMap ProtocolServer (TMVar a) -> STM (Either (TMVar a) (TMVar a))
+getClientVar srv clients = maybe (Left <$> newClientVar) (pure . Right) =<< TM.lookup srv clients
+  where
+    newClientVar :: STM (TMVar a)
+    newClientVar = do
+      var <- newEmptyTMVar
+      TM.insert srv var clients
+      pure var
+
+waitForProtocolClient :: AgentMonad m => (AgentConfig -> ProtocolClientConfig) -> ClientVar msg -> m (ProtocolClient msg)
+waitForProtocolClient clientConfig clientVar = do
+  ProtocolClientConfig {tcpTimeout} <- asks $ clientConfig . config
+  client_ <- liftIO $ tcpTimeout `timeout` atomically (readTMVar clientVar)
+  liftEither $ case client_ of
+    Just (Right smpClient) -> Right smpClient
+    Just (Left e) -> Left e
+    Nothing -> Left $ BROKER TIMEOUT
+
+newProtocolClient ::
+  forall msg m.
+  AgentMonad m =>
+  AgentClient ->
+  ProtocolServer ->
+  TMap ProtocolServer (ClientVar msg) ->
+  m (ProtocolClient msg) ->
+  m () ->
+  ClientVar msg ->
+  m (ProtocolClient msg)
+newProtocolClient c srv clients connectClient reconnectClient clientVar = tryConnectClient pure tryConnectAsync
+  where
+    tryConnectClient :: (ProtocolClient msg -> m a) -> m () -> m a
+    tryConnectClient successAction retryAction =
+      tryError connectClient >>= \r -> case r of
+        Right client -> do
+          logInfo . decodeUtf8 $ "Agent connected to " <> showServer srv
+          atomically $ putTMVar clientVar r
+          successAction client
+        Left e -> do
+          if e == BROKER NETWORK || e == BROKER TIMEOUT
+            then retryAction
+            else atomically $ do
+              putTMVar clientVar (Left e)
+              TM.delete srv clients
+          throwError e
+    tryConnectAsync :: m ()
+    tryConnectAsync = do
+      a <- async connectAsync
+      atomically $ modifyTVar' (asyncClients c) (a :)
+    connectAsync :: m ()
+    connectAsync = do
+      ri <- asks $ reconnectInterval . config
+      withRetryInterval ri $ \loop -> void $ tryConnectClient (const reconnectClient) loop
+
+closeAgentClient :: MonadIO m => AgentClient -> m ()
+closeAgentClient c = liftIO $ do
+  atomically $ writeTVar (active c) False
+  closeProtocolServerClients (clientTimeout smpCfg) $ smpClients c
+  closeProtocolServerClients (clientTimeout ntfCfg) $ ntfClients c
+  cancelActions $ reconnections c
+  cancelActions $ asyncClients c
+  cancelActions $ smpQueueMsgDeliveries c
+  clear subscrSrvrs
+  clear pendingSubscrSrvrs
+  clear subscrConns
+  clear connMsgsQueued
+  clear smpQueueMsgQueues
+  where
+    clientTimeout sel = tcpTimeout . sel . config $ agentEnv c
+    clear sel = atomically $ writeTVar (sel c) M.empty
+
+closeProtocolServerClients :: Int -> TMap ProtocolServer (ClientVar msg) -> IO ()
+closeProtocolServerClients tcpTimeout cs = readTVarIO cs >>= mapM_ (forkIO . closeClient) >> atomically (writeTVar cs M.empty)
+  where
+    closeClient cVar =
+      tcpTimeout `timeout` atomically (readTMVar cVar) >>= \case
+        Just (Right client) -> closeProtocolClient client `catchAll_` pure ()
+        _ -> pure ()
+
+cancelActions :: (Foldable f, Monoid (f (Async ()))) => TVar (f (Async ())) -> IO ()
+cancelActions as = readTVarIO as >>= mapM_ uninterruptibleCancel >> atomically (writeTVar as mempty)
+
+withAgentLock :: MonadUnliftIO m => AgentClient -> m a -> m a
+withAgentLock AgentClient {lock} =
+  E.bracket_
+    (void . atomically $ takeTMVar lock)
+    (atomically $ putTMVar lock ())
+
+withClient_ :: forall a m msg. (AgentMonad m, ProtocolServerClient msg) => AgentClient -> ProtocolServer -> (ProtocolClient msg -> m a) -> m a
+withClient_ c srv action = (getProtocolServerClient c srv >>= action) `catchError` logServerError
+  where
+    logServerError :: AgentErrorType -> m a
+    logServerError e = do
+      logServer "<--" c srv "" $ bshow e
+      throwError e
+
+withLogClient_ :: (AgentMonad m, ProtocolServerClient msg) => AgentClient -> ProtocolServer -> QueueId -> ByteString -> (ProtocolClient msg -> m a) -> m a
+withLogClient_ c srv qId cmdStr action = do
+  logServer "-->" c srv qId cmdStr
+  res <- withClient_ c srv action
+  logServer "<--" c srv qId "OK"
+  return res
+
+withClient :: forall m msg a. (AgentMonad m, ProtocolServerClient msg) => AgentClient -> ProtocolServer -> (ProtocolClient msg -> ExceptT ProtocolClientError IO a) -> m a
+withClient c srv action = withClient_ c srv $ liftClient (protocolError @msg) . action
+
+withLogClient :: forall m msg a. (AgentMonad m, ProtocolServerClient msg) => AgentClient -> ProtocolServer -> QueueId -> ByteString -> (ProtocolClient msg -> ExceptT ProtocolClientError IO a) -> m a
+withLogClient c srv qId cmdStr action = withLogClient_ c srv qId cmdStr $ liftClient (protocolError @msg) . action
+
+liftClient :: AgentMonad m => (ErrorType -> AgentErrorType) -> ExceptT ProtocolClientError IO a -> m a
+liftClient = liftError . protocolClientError
+
+protocolClientError :: (ErrorType -> AgentErrorType) -> ProtocolClientError -> AgentErrorType
+protocolClientError protocolError_ = \case
+  PCEProtocolError e -> protocolError_ e
+  PCEResponseError e -> BROKER $ RESPONSE e
+  PCEUnexpectedResponse -> BROKER UNEXPECTED
+  PCEResponseTimeout -> BROKER TIMEOUT
+  PCENetworkError -> BROKER NETWORK
+  PCETransportError e -> BROKER $ TRANSPORT e
+  e@PCESignatureError {} -> INTERNAL $ show e
+  e@PCEIOError {} -> INTERNAL $ show e
+
+newRcvQueue :: AgentMonad m => AgentClient -> SMPServer -> m (RcvQueue, SMPQueueUri)
+newRcvQueue c srv =
+  asks (cmdSignAlg . config) >>= \case
+    C.SignAlg a -> newRcvQueue_ a c srv
+
+newRcvQueue_ ::
+  (C.SignatureAlgorithm a, C.AlgorithmI a, AgentMonad m) =>
+  C.SAlgorithm a ->
+  AgentClient ->
+  SMPServer ->
+  m (RcvQueue, SMPQueueUri)
+newRcvQueue_ a c srv = do
+  (recipientKey, rcvPrivateKey) <- liftIO $ C.generateSignatureKeyPair a
+  (dhKey, privDhKey) <- liftIO C.generateKeyPair'
+  (e2eDhKey, e2ePrivKey) <- liftIO C.generateKeyPair'
+  logServer "-->" c srv "" "NEW"
+  QIK {rcvId, sndId, rcvPublicDhKey} <-
+    withClient c srv $ \smp -> createSMPQueue smp rcvPrivateKey recipientKey dhKey
+  logServer "<--" c srv "" $ B.unwords ["IDS", logSecret rcvId, logSecret sndId]
+  let rq =
+        RcvQueue
+          { server = srv,
+            rcvId,
+            rcvPrivateKey,
+            rcvDhSecret = C.dh' rcvPublicDhKey privDhKey,
+            e2ePrivKey,
+            e2eDhSecret = Nothing,
+            sndId = Just sndId,
+            status = New
+          }
+  pure (rq, SMPQueueUri srv sndId SMP.smpClientVRange e2eDhKey)
+
+subscribeQueue :: AgentMonad m => AgentClient -> RcvQueue -> ConnId -> m ()
+subscribeQueue c rq@RcvQueue {server, rcvPrivateKey, rcvId} connId = do
+  atomically $ addPendingSubscription c rq connId
+  withLogClient c server rcvId "SUB" $ \smp -> do
+    liftIO (runExceptT $ subscribeSMPQueue smp rcvPrivateKey rcvId) >>= \case
+      Left e -> do
+        atomically . when (e /= PCENetworkError && e /= PCEResponseTimeout) $
+          removePendingSubscription c server connId
+        throwError e
+      Right _ -> addSubscription c rq connId
+
+addSubscription :: MonadIO m => AgentClient -> RcvQueue -> ConnId -> m ()
+addSubscription c rq@RcvQueue {server} connId = atomically $ do
+  TM.insert connId server $ subscrConns c
+  addSubs_ (subscrSrvrs c) rq connId
+  removePendingSubscription c server connId
+
+hasActiveSubscription :: AgentClient -> ConnId -> STM Bool
+hasActiveSubscription c connId = TM.member connId (subscrConns c)
+
+addPendingSubscription :: AgentClient -> RcvQueue -> ConnId -> STM ()
+addPendingSubscription = addSubs_ . pendingSubscrSrvrs
+
+addSubs_ :: TMap SMPServer (TMap ConnId RcvQueue) -> RcvQueue -> ConnId -> STM ()
+addSubs_ ss rq@RcvQueue {server} connId =
+  TM.lookup server ss >>= \case
+    Just m -> TM.insert connId rq m
+    _ -> TM.singleton connId rq >>= \m -> TM.insert server m ss
+
+removeSubscription :: AgentClient -> ConnId -> STM ()
+removeSubscription c@AgentClient {subscrConns} connId = do
+  server_ <- TM.lookupDelete connId subscrConns
+  mapM_ (\server -> removeSubs_ (subscrSrvrs c) server connId) server_
+
+removePendingSubscription :: AgentClient -> SMPServer -> ConnId -> STM ()
+removePendingSubscription = removeSubs_ . pendingSubscrSrvrs
+
+removeSubs_ :: TMap SMPServer (TMap ConnId RcvQueue) -> SMPServer -> ConnId -> STM ()
+removeSubs_ ss server connId =
+  TM.lookup server ss >>= mapM_ (TM.delete connId)
+
+logServer :: MonadIO m => ByteString -> AgentClient -> SMPServer -> QueueId -> ByteString -> m ()
+logServer dir AgentClient {clientId} srv qId cmdStr =
+  logInfo . decodeUtf8 $ B.unwords ["A", "(" <> bshow clientId <> ")", dir, showServer srv, ":", logSecret qId, cmdStr]
+
+showServer :: SMPServer -> ByteString
+showServer ProtocolServer {host, port} =
+  B.pack $ host <> if null port then "" else ':' : port
+
+logSecret :: ByteString -> ByteString
+logSecret bs = encode $ B.take 3 bs
+
+sendConfirmation :: forall m. AgentMonad m => AgentClient -> SndQueue -> ByteString -> m ()
+sendConfirmation c sq@SndQueue {server, sndId, sndPublicKey = Just sndPublicKey, e2ePubKey = e2ePubKey@Just {}} agentConfirmation =
+  withLogClient_ c server sndId "SEND <CONF>" $ \smp -> do
+    let clientMsg = SMP.ClientMessage (SMP.PHConfirmation sndPublicKey) agentConfirmation
+    msg <- agentCbEncrypt sq e2ePubKey $ smpEncode clientMsg
+    liftClient SMP $ sendSMPMessage smp Nothing sndId msg
+sendConfirmation _ _ _ = throwError $ INTERNAL "sendConfirmation called without snd_queue public key(s) in the database"
+
+sendInvitation :: forall m. AgentMonad m => AgentClient -> Compatible SMPQueueInfo -> ConnectionRequestUri 'CMInvitation -> ConnInfo -> m ()
+sendInvitation c (Compatible SMPQueueInfo {smpServer, senderId, dhPublicKey}) connReq connInfo =
+  withLogClient_ c smpServer senderId "SEND <INV>" $ \smp -> do
+    msg <- mkInvitation
+    liftClient SMP $ sendSMPMessage smp Nothing senderId msg
+  where
+    mkInvitation :: m ByteString
+    -- this is only encrypted with per-queue E2E, not with double ratchet
+    mkInvitation = do
+      let agentEnvelope = AgentInvitation {agentVersion = smpAgentVersion, connReq, connInfo}
+      agentCbEncryptOnce dhPublicKey . smpEncode $
+        SMP.ClientMessage SMP.PHEmpty $ smpEncode agentEnvelope
+
+secureQueue :: AgentMonad m => AgentClient -> RcvQueue -> SndPublicVerifyKey -> m ()
+secureQueue c RcvQueue {server, rcvId, rcvPrivateKey} senderKey =
+  withLogClient c server rcvId "KEY <key>" $ \smp ->
+    secureSMPQueue smp rcvPrivateKey rcvId senderKey
+
+sendAck :: AgentMonad m => AgentClient -> RcvQueue -> m ()
+sendAck c RcvQueue {server, rcvId, rcvPrivateKey} =
+  withLogClient c server rcvId "ACK" $ \smp ->
+    ackSMPMessage smp rcvPrivateKey rcvId
+
+suspendQueue :: AgentMonad m => AgentClient -> RcvQueue -> m ()
+suspendQueue c RcvQueue {server, rcvId, rcvPrivateKey} =
+  withLogClient c server rcvId "OFF" $ \smp ->
+    suspendSMPQueue smp rcvPrivateKey rcvId
+
+deleteQueue :: AgentMonad m => AgentClient -> RcvQueue -> m ()
+deleteQueue c RcvQueue {server, rcvId, rcvPrivateKey} =
+  withLogClient c server rcvId "DEL" $ \smp ->
+    deleteSMPQueue smp rcvPrivateKey rcvId
+
+sendAgentMessage :: forall m. AgentMonad m => AgentClient -> SndQueue -> ByteString -> m ()
+sendAgentMessage c sq@SndQueue {server, sndId, sndPrivateKey} agentMsg =
+  withLogClient_ c server sndId "SEND <MSG>" $ \smp -> do
+    let clientMsg = SMP.ClientMessage SMP.PHEmpty agentMsg
+    msg <- agentCbEncrypt sq Nothing $ smpEncode clientMsg
+    liftClient SMP $ sendSMPMessage smp (Just sndPrivateKey) sndId msg
+
+agentNtfRegisterToken :: AgentMonad m => AgentClient -> NtfToken -> C.APublicVerifyKey -> C.PublicKeyX25519 -> m (NtfTokenId, C.PublicKeyX25519)
+agentNtfRegisterToken c NtfToken {deviceToken, ntfServer, ntfPrivKey} ntfPubKey pubDhKey =
+  withClient c ntfServer $ \ntf -> ntfRegisterToken ntf ntfPrivKey (NewNtfTkn deviceToken ntfPubKey pubDhKey)
+
+agentNtfVerifyToken :: AgentMonad m => AgentClient -> NtfTokenId -> NtfToken -> NtfRegCode -> m ()
+agentNtfVerifyToken c tknId NtfToken {ntfServer, ntfPrivKey} code =
+  withLogClient c ntfServer tknId "TVFY" $ \ntf -> ntfVerifyToken ntf ntfPrivKey tknId code
+
+agentNtfCheckToken :: AgentMonad m => AgentClient -> NtfTokenId -> NtfToken -> m NtfTknStatus
+agentNtfCheckToken c tknId NtfToken {ntfServer, ntfPrivKey} =
+  withLogClient c ntfServer tknId "TCHK" $ \ntf -> ntfCheckToken ntf ntfPrivKey tknId
+
+agentNtfDeleteToken :: AgentMonad m => AgentClient -> NtfTokenId -> NtfToken -> m ()
+agentNtfDeleteToken c tknId NtfToken {ntfServer, ntfPrivKey} =
+  withLogClient c ntfServer tknId "TDEL" $ \ntf -> ntfDeleteToken ntf ntfPrivKey tknId
+
+agentNtfEnableCron :: AgentMonad m => AgentClient -> NtfTokenId -> NtfToken -> Word16 -> m ()
+agentNtfEnableCron c tknId NtfToken {ntfServer, ntfPrivKey} interval =
+  withLogClient c ntfServer tknId "TCRN" $ \ntf -> ntfEnableCron ntf ntfPrivKey tknId interval
+
+agentCbEncrypt :: AgentMonad m => SndQueue -> Maybe C.PublicKeyX25519 -> ByteString -> m ByteString
+agentCbEncrypt SndQueue {e2eDhSecret} e2ePubKey msg = do
+  cmNonce <- liftIO C.randomCbNonce
+  let paddedLen = maybe SMP.e2eEncMessageLength (const SMP.e2eEncConfirmationLength) e2ePubKey
+  cmEncBody <-
+    liftEither . first cryptoError $
+      C.cbEncrypt e2eDhSecret cmNonce msg paddedLen
+  -- TODO per-queue client version
+  let cmHeader = SMP.PubHeader (maxVersion SMP.smpClientVRange) e2ePubKey
+  pure $ smpEncode SMP.ClientMsgEnvelope {cmHeader, cmNonce, cmEncBody}
+
+-- add encoding as AgentInvitation'?
+agentCbEncryptOnce :: AgentMonad m => C.PublicKeyX25519 -> ByteString -> m ByteString
+agentCbEncryptOnce dhRcvPubKey msg = do
+  (dhSndPubKey, dhSndPrivKey) <- liftIO C.generateKeyPair'
+  let e2eDhSecret = C.dh' dhRcvPubKey dhSndPrivKey
+  cmNonce <- liftIO C.randomCbNonce
+  cmEncBody <-
+    liftEither . first cryptoError $
+      C.cbEncrypt e2eDhSecret cmNonce msg SMP.e2eEncConfirmationLength
+  -- TODO per-queue client version
+  let cmHeader = SMP.PubHeader (maxVersion SMP.smpClientVRange) (Just dhSndPubKey)
+  pure $ smpEncode SMP.ClientMsgEnvelope {cmHeader, cmNonce, cmEncBody}
+
+-- | NaCl crypto-box decrypt - both for messages received from the server
+-- and per-queue E2E encrypted messages from the sender that were inside.
+agentCbDecrypt :: AgentMonad m => C.DhSecretX25519 -> C.CbNonce -> ByteString -> m ByteString
+agentCbDecrypt dhSecret nonce msg =
+  liftEither . first cryptoError $
+    C.cbDecrypt dhSecret nonce msg
+
+cryptoError :: C.CryptoError -> AgentErrorType
+cryptoError = \case
+  C.CryptoLargeMsgError -> CMD LARGE
+  C.CryptoHeaderError _ -> AGENT A_ENCRYPTION
+  C.AESDecryptError -> AGENT A_ENCRYPTION
+  C.CBDecryptError -> AGENT A_ENCRYPTION
+  e -> INTERNAL $ show e

src/Simplex/Messaging/Agent/Env/SQLite.hs

@@ -0,0 +1,104 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE NumericUnderscores #-}
+{-# LANGUAGE TypeApplications #-}
+{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}
+
+module Simplex.Messaging.Agent.Env.SQLite
+  ( AgentConfig (..),
+    InitialAgentServers (..),
+    defaultAgentConfig,
+    defaultReconnectInterval,
+    Env (..),
+    newSMPAgentEnv,
+  )
+where
+
+import Control.Monad.IO.Unlift
+import Crypto.Random
+import Data.List.NonEmpty (NonEmpty)
+import Data.Time.Clock (NominalDiffTime, nominalDay)
+import Network.Socket
+import Numeric.Natural
+import Simplex.Messaging.Agent.Protocol (SMPServer)
+import Simplex.Messaging.Agent.RetryInterval
+import Simplex.Messaging.Agent.Store.SQLite
+import qualified Simplex.Messaging.Agent.Store.SQLite.Migrations as Migrations
+import Simplex.Messaging.Client
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Notifications.Client (NtfServer)
+import Simplex.Messaging.Transport (TLS, Transport (..))
+import System.Random (StdGen, newStdGen)
+import UnliftIO.STM
+
+data InitialAgentServers = InitialAgentServers
+  { smp :: NonEmpty SMPServer,
+    ntf :: [NtfServer]
+  }
+
+data AgentConfig = AgentConfig
+  { tcpPort :: ServiceName,
+    cmdSignAlg :: C.SignAlg,
+    connIdBytes :: Int,
+    tbqSize :: Natural,
+    dbFile :: FilePath,
+    dbPoolSize :: Int,
+    yesToMigrations :: Bool,
+    smpCfg :: ProtocolClientConfig,
+    ntfCfg :: ProtocolClientConfig,
+    reconnectInterval :: RetryInterval,
+    helloTimeout :: NominalDiffTime,
+    resubscriptionConcurrency :: Int,
+    caCertificateFile :: FilePath,
+    privateKeyFile :: FilePath,
+    certificateFile :: FilePath
+  }
+
+defaultReconnectInterval :: RetryInterval
+defaultReconnectInterval =
+  RetryInterval
+    { initialInterval = second,
+      increaseAfter = 10 * second,
+      maxInterval = 10 * second
+    }
+  where
+    second = 1_000_000
+
+defaultAgentConfig :: AgentConfig
+defaultAgentConfig =
+  AgentConfig
+    { tcpPort = "5224",
+      cmdSignAlg = C.SignAlg C.SEd448,
+      connIdBytes = 12,
+      tbqSize = 64,
+      dbFile = "smp-agent.db",
+      dbPoolSize = 4,
+      yesToMigrations = False,
+      smpCfg = defaultClientConfig {defaultTransport = ("5223", transport @TLS)},
+      ntfCfg = defaultClientConfig {defaultTransport = ("443", transport @TLS)},
+      reconnectInterval = defaultReconnectInterval,
+      helloTimeout = 2 * nominalDay,
+      resubscriptionConcurrency = 16,
+      -- CA certificate private key is not needed for initialization
+      -- ! we do not generate these
+      caCertificateFile = "/etc/opt/simplex-agent/ca.crt",
+      privateKeyFile = "/etc/opt/simplex-agent/agent.key",
+      certificateFile = "/etc/opt/simplex-agent/agent.crt"
+    }
+
+data Env = Env
+  { config :: AgentConfig,
+    store :: SQLiteStore,
+    idsDrg :: TVar ChaChaDRG,
+    clientCounter :: TVar Int,
+    randomServer :: TVar StdGen
+  }
+
+newSMPAgentEnv :: (MonadUnliftIO m, MonadRandom m) => AgentConfig -> m Env
+newSMPAgentEnv config@AgentConfig {dbFile, dbPoolSize, yesToMigrations} = do
+  idsDrg <- newTVarIO =<< drgNew
+  store <- liftIO $ createSQLiteStore dbFile dbPoolSize Migrations.app yesToMigrations
+  clientCounter <- newTVarIO 0
+  randomServer <- newTVarIO =<< liftIO newStdGen
+  return Env {config, store, idsDrg, clientCounter, randomServer}

src/Simplex/Messaging/Agent/Protocol.hs

@@ -0,0 +1,975 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE PolyKinds #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}
+
+-- |
+-- Module      : Simplex.Messaging.Agent.Protocol
+-- Copyright   : (c) simplex.chat
+-- License     : AGPL-3
+--
+-- Maintainer  : chat@simplex.chat
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Types, parsers, serializers and functions to send and receive SMP agent protocol commands and responses.
+--
+-- See https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md
+module Simplex.Messaging.Agent.Protocol
+  ( -- * Protocol parameters
+    smpAgentVersion,
+    smpAgentVRange,
+    e2eEncConnInfoLength,
+    e2eEncUserMsgLength,
+
+    -- * SMP agent protocol types
+    ConnInfo,
+    ACommand (..),
+    AParty (..),
+    SAParty (..),
+    MsgHash,
+    MsgMeta (..),
+    SMPConfirmation (..),
+    AgentMsgEnvelope (..),
+    AgentMessage (..),
+    AgentMessageType (..),
+    APrivHeader (..),
+    AMessage (..),
+    SMPServer,
+    pattern SMPServer,
+    SrvLoc (..),
+    SMPQueueUri (..),
+    SMPQueueInfo (..),
+    ConnectionMode (..),
+    SConnectionMode (..),
+    AConnectionMode (..),
+    cmInvitation,
+    cmContact,
+    ConnectionModeI (..),
+    ConnectionRequestUri (..),
+    AConnectionRequestUri (..),
+    ConnReqUriData (..),
+    ConnReqScheme (..),
+    simplexChat,
+    AgentErrorType (..),
+    CommandErrorType (..),
+    ConnectionErrorType (..),
+    BrokerErrorType (..),
+    SMPAgentError (..),
+    ATransmission,
+    ATransmissionOrError,
+    ARawTransmission,
+    ConnId,
+    ConfirmationId,
+    InvitationId,
+    MsgIntegrity (..),
+    MsgErrorType (..),
+    QueueStatus (..),
+    ACorrId,
+    AgentMsgId,
+
+    -- * Encode/decode
+    serializeCommand,
+    connMode,
+    connMode',
+    commandP,
+    connModeT,
+    serializeQueueStatus,
+    queueStatusT,
+    agentMessageType,
+
+    -- * TCP transport functions
+    tPut,
+    tGet,
+    tPutRaw,
+    tGetRaw,
+  )
+where
+
+import Control.Applicative (optional, (<|>))
+import Control.Monad.IO.Class
+import Data.Aeson (FromJSON (..), ToJSON (..))
+import qualified Data.Aeson as J
+import Data.Attoparsec.ByteString.Char8 (Parser)
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.ByteString.Base64
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Composition ((.:))
+import Data.Functor (($>))
+import Data.Int (Int64)
+import Data.Kind (Type)
+import qualified Data.List.NonEmpty as L
+import Data.Maybe (isJust)
+import Data.Text (Text)
+import Data.Time.Clock (UTCTime)
+import Data.Time.ISO8601
+import Data.Type.Equality
+import Data.Typeable ()
+import GHC.Generics (Generic)
+import Generic.Random (genericArbitraryU)
+import Simplex.Messaging.Agent.QueryString
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Crypto.Ratchet (E2ERatchetParams, E2ERatchetParamsUri)
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Parsers
+import Simplex.Messaging.Protocol
+  ( ErrorType,
+    MsgBody,
+    MsgId,
+    SMPServer,
+    SndPublicVerifyKey,
+    SrvLoc (..),
+    pattern SMPServer,
+  )
+import qualified Simplex.Messaging.Protocol as SMP
+import Simplex.Messaging.Transport (Transport (..), TransportError, serializeTransportError, transportErrorP)
+import Simplex.Messaging.Util
+import Simplex.Messaging.Version
+import Test.QuickCheck (Arbitrary (..))
+import Text.Read
+import UnliftIO.Exception (Exception)
+
+smpAgentVersion :: Version
+smpAgentVersion = 1
+
+smpAgentVRange :: VersionRange
+smpAgentVRange = mkVersionRange 1 smpAgentVersion
+
+-- it is shorter to allow all handshake headers,
+-- including E2E (double-ratchet) parameters and
+-- signing key of the sender for the server
+e2eEncConnInfoLength :: Int
+e2eEncConnInfoLength = 14848
+
+e2eEncUserMsgLength :: Int
+e2eEncUserMsgLength = 15856
+
+-- | Raw (unparsed) SMP agent protocol transmission.
+type ARawTransmission = (ByteString, ByteString, ByteString)
+
+-- | Parsed SMP agent protocol transmission.
+type ATransmission p = (ACorrId, ConnId, ACommand p)
+
+-- | SMP agent protocol transmission or transmission error.
+type ATransmissionOrError p = (ACorrId, ConnId, Either AgentErrorType (ACommand p))
+
+type ACorrId = ByteString
+
+-- | SMP agent protocol participants.
+data AParty = Agent | Client
+  deriving (Eq, Show)
+
+-- | Singleton types for SMP agent protocol participants.
+data SAParty :: AParty -> Type where
+  SAgent :: SAParty Agent
+  SClient :: SAParty Client
+
+deriving instance Show (SAParty p)
+
+deriving instance Eq (SAParty p)
+
+instance TestEquality SAParty where
+  testEquality SAgent SAgent = Just Refl
+  testEquality SClient SClient = Just Refl
+  testEquality _ _ = Nothing
+
+data ACmd = forall p. ACmd (SAParty p) (ACommand p)
+
+deriving instance Show ACmd
+
+type ConnInfo = ByteString
+
+-- | Parameterized type for SMP agent protocol commands and responses from all participants.
+data ACommand (p :: AParty) where
+  NEW :: AConnectionMode -> ACommand Client -- response INV
+  INV :: AConnectionRequestUri -> ACommand Agent
+  JOIN :: AConnectionRequestUri -> ConnInfo -> ACommand Client -- response OK
+  CONF :: ConfirmationId -> ConnInfo -> ACommand Agent -- ConnInfo is from sender
+  LET :: ConfirmationId -> ConnInfo -> ACommand Client -- ConnInfo is from client
+  REQ :: InvitationId -> ConnInfo -> ACommand Agent -- ConnInfo is from sender
+  ACPT :: InvitationId -> ConnInfo -> ACommand Client -- ConnInfo is from client
+  RJCT :: InvitationId -> ACommand Client
+  INFO :: ConnInfo -> ACommand Agent
+  CON :: ACommand Agent -- notification that connection is established
+  SUB :: ACommand Client
+  END :: ACommand Agent
+  DOWN :: SMPServer -> [ConnId] -> ACommand Agent
+  UP :: SMPServer -> [ConnId] -> ACommand Agent
+  SEND :: MsgBody -> ACommand Client
+  MID :: AgentMsgId -> ACommand Agent
+  SENT :: AgentMsgId -> ACommand Agent
+  MERR :: AgentMsgId -> AgentErrorType -> ACommand Agent
+  MSG :: MsgMeta -> MsgBody -> ACommand Agent
+  ACK :: AgentMsgId -> ACommand Client
+  OFF :: ACommand Client
+  DEL :: ACommand Client
+  OK :: ACommand Agent
+  ERR :: AgentErrorType -> ACommand Agent
+
+deriving instance Eq (ACommand p)
+
+deriving instance Show (ACommand p)
+
+data ConnectionMode = CMInvitation | CMContact
+  deriving (Eq, Show)
+
+data SConnectionMode (m :: ConnectionMode) where
+  SCMInvitation :: SConnectionMode CMInvitation
+  SCMContact :: SConnectionMode CMContact
+
+deriving instance Eq (SConnectionMode m)
+
+deriving instance Show (SConnectionMode m)
+
+instance TestEquality SConnectionMode where
+  testEquality SCMInvitation SCMInvitation = Just Refl
+  testEquality SCMContact SCMContact = Just Refl
+  testEquality _ _ = Nothing
+
+data AConnectionMode = forall m. ConnectionModeI m => ACM (SConnectionMode m)
+
+instance Eq AConnectionMode where
+  ACM m == ACM m' = isJust $ testEquality m m'
+
+cmInvitation :: AConnectionMode
+cmInvitation = ACM SCMInvitation
+
+cmContact :: AConnectionMode
+cmContact = ACM SCMContact
+
+deriving instance Show AConnectionMode
+
+connMode :: SConnectionMode m -> ConnectionMode
+connMode SCMInvitation = CMInvitation
+connMode SCMContact = CMContact
+
+connMode' :: ConnectionMode -> AConnectionMode
+connMode' CMInvitation = cmInvitation
+connMode' CMContact = cmContact
+
+class ConnectionModeI (m :: ConnectionMode) where sConnectionMode :: SConnectionMode m
+
+instance ConnectionModeI CMInvitation where sConnectionMode = SCMInvitation
+
+instance ConnectionModeI CMContact where sConnectionMode = SCMContact
+
+type MsgHash = ByteString
+
+-- | Agent message metadata sent to the client
+data MsgMeta = MsgMeta
+  { integrity :: MsgIntegrity,
+    recipient :: (AgentMsgId, UTCTime),
+    broker :: (MsgId, UTCTime),
+    sndMsgId :: AgentMsgId
+  }
+  deriving (Eq, Show)
+
+data SMPConfirmation = SMPConfirmation
+  { -- | sender's public key to use for authentication of sender's commands at the recepient's server
+    senderKey :: SndPublicVerifyKey,
+    -- | sender's DH public key for simple per-queue e2e encryption
+    e2ePubKey :: C.PublicKeyX25519,
+    -- | sender's information to be associated with the connection, e.g. sender's profile information
+    connInfo :: ConnInfo
+  }
+  deriving (Show)
+
+data AgentMsgEnvelope
+  = AgentConfirmation
+      { agentVersion :: Version,
+        e2eEncryption :: Maybe (E2ERatchetParams 'C.X448),
+        encConnInfo :: ByteString
+      }
+  | AgentMsgEnvelope
+      { agentVersion :: Version,
+        encAgentMessage :: ByteString
+      }
+  | AgentInvitation -- the connInfo in contactInvite is only encrypted with per-queue E2E, not with double ratchet,
+      { agentVersion :: Version,
+        connReq :: ConnectionRequestUri 'CMInvitation,
+        connInfo :: ByteString -- this message is only encrypted with per-queue E2E, not with double ratchet,
+      }
+  deriving (Show)
+
+instance Encoding AgentMsgEnvelope where
+  smpEncode = \case
+    AgentConfirmation {agentVersion, e2eEncryption, encConnInfo} ->
+      smpEncode (agentVersion, 'C', e2eEncryption, Tail encConnInfo)
+    AgentMsgEnvelope {agentVersion, encAgentMessage} ->
+      smpEncode (agentVersion, 'M', Tail encAgentMessage)
+    AgentInvitation {agentVersion, connReq, connInfo} ->
+      smpEncode (agentVersion, 'I', Large $ strEncode connReq, Tail connInfo)
+  smpP = do
+    agentVersion <- smpP
+    smpP >>= \case
+      'C' -> do
+        (e2eEncryption, Tail encConnInfo) <- smpP
+        pure AgentConfirmation {agentVersion, e2eEncryption, encConnInfo}
+      'M' -> do
+        Tail encAgentMessage <- smpP
+        pure AgentMsgEnvelope {agentVersion, encAgentMessage}
+      'I' -> do
+        connReq <- strDecode . unLarge <$?> smpP
+        Tail connInfo <- smpP
+        pure AgentInvitation {agentVersion, connReq, connInfo}
+      _ -> fail "bad AgentMsgEnvelope"
+
+-- SMP agent message formats (after double ratchet decryption,
+-- or in case of AgentInvitation - in plain text body)
+data AgentMessage = AgentConnInfo ConnInfo | AgentMessage APrivHeader AMessage
+  deriving (Show)
+
+instance Encoding AgentMessage where
+  smpEncode = \case
+    AgentConnInfo cInfo -> smpEncode ('I', Tail cInfo)
+    AgentMessage hdr aMsg -> smpEncode ('M', hdr, aMsg)
+  smpP =
+    smpP >>= \case
+      'I' -> AgentConnInfo . unTail <$> smpP
+      'M' -> AgentMessage <$> smpP <*> smpP
+      _ -> fail "bad AgentMessage"
+
+data AgentMessageType = AM_CONN_INFO | AM_HELLO_ | AM_REPLY_ | AM_A_MSG_
+  deriving (Eq, Show)
+
+instance Encoding AgentMessageType where
+  smpEncode = \case
+    AM_CONN_INFO -> "C"
+    AM_HELLO_ -> "H"
+    AM_REPLY_ -> "R"
+    AM_A_MSG_ -> "M"
+  smpP =
+    A.anyChar >>= \case
+      'C' -> pure AM_CONN_INFO
+      'H' -> pure AM_HELLO_
+      'R' -> pure AM_REPLY_
+      'M' -> pure AM_A_MSG_
+      _ -> fail "bad AgentMessageType"
+
+agentMessageType :: AgentMessage -> AgentMessageType
+agentMessageType = \case
+  AgentConnInfo _ -> AM_CONN_INFO
+  AgentMessage _ aMsg -> case aMsg of
+    HELLO -> AM_HELLO_
+    REPLY _ -> AM_REPLY_
+    A_MSG _ -> AM_A_MSG_
+
+data APrivHeader = APrivHeader
+  { -- | sequential ID assigned by the sending agent
+    sndMsgId :: AgentMsgId,
+    -- | digest of the previous message
+    prevMsgHash :: MsgHash
+  }
+  deriving (Show)
+
+instance Encoding APrivHeader where
+  smpEncode APrivHeader {sndMsgId, prevMsgHash} =
+    smpEncode (sndMsgId, prevMsgHash)
+  smpP = APrivHeader <$> smpP <*> smpP
+
+data AMsgType = HELLO_ | REPLY_ | A_MSG_
+  deriving (Eq)
+
+instance Encoding AMsgType where
+  smpEncode = \case
+    HELLO_ -> "H"
+    REPLY_ -> "R"
+    A_MSG_ -> "M"
+  smpP =
+    smpP >>= \case
+      'H' -> pure HELLO_
+      'R' -> pure REPLY_
+      'M' -> pure A_MSG_
+      _ -> fail "bad AMsgType"
+
+-- | Messages sent between SMP agents once SMP queue is secured.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/agent-protocol.md#messages-between-smp-agents
+data AMessage
+  = -- | the first message in the queue to validate it is secured
+    HELLO
+  | -- | reply queues information
+    REPLY (L.NonEmpty SMPQueueInfo)
+  | -- | agent envelope for the client message
+    A_MSG MsgBody
+  deriving (Show)
+
+instance Encoding AMessage where
+  smpEncode = \case
+    HELLO -> smpEncode HELLO_
+    REPLY smpQueues -> smpEncode (REPLY_, smpQueues)
+    A_MSG body -> smpEncode (A_MSG_, Tail body)
+  smpP =
+    smpP
+      >>= \case
+        HELLO_ -> pure HELLO
+        REPLY_ -> REPLY <$> smpP
+        A_MSG_ -> A_MSG . unTail <$> smpP
+
+instance forall m. ConnectionModeI m => StrEncoding (ConnectionRequestUri m) where
+  strEncode = \case
+    CRInvitationUri crData e2eParams -> crEncode "invitation" crData (Just e2eParams)
+    CRContactUri crData -> crEncode "contact" crData Nothing
+    where
+      crEncode :: ByteString -> ConnReqUriData -> Maybe (E2ERatchetParamsUri 'C.X448) -> ByteString
+      crEncode crMode ConnReqUriData {crScheme, crAgentVRange, crSmpQueues} e2eParams =
+        strEncode crScheme <> "/" <> crMode <> "#/?" <> queryStr
+        where
+          queryStr =
+            strEncode . QSP QEscape $
+              [("v", strEncode crAgentVRange), ("smp", strEncode crSmpQueues)]
+                <> maybe [] (\e2e -> [("e2e", strEncode e2e)]) e2eParams
+  strP = do
+    ACR m cr <- strP
+    case testEquality m $ sConnectionMode @m of
+      Just Refl -> pure cr
+      _ -> fail "bad connection request mode"
+
+instance StrEncoding AConnectionRequestUri where
+  strEncode (ACR _ cr) = strEncode cr
+  strP = do
+    crScheme <- strP
+    crMode <- A.char '/' *> crModeP <* optional (A.char '/') <* "#/?"
+    query <- strP
+    crAgentVRange <- queryParam "v" query
+    crSmpQueues <- queryParam "smp" query
+    let crData = ConnReqUriData {crScheme, crAgentVRange, crSmpQueues}
+    case crMode of
+      CMInvitation -> do
+        crE2eParams <- queryParam "e2e" query
+        pure . ACR SCMInvitation $ CRInvitationUri crData crE2eParams
+      CMContact -> pure . ACR SCMContact $ CRContactUri crData
+    where
+      crModeP = "invitation" $> CMInvitation <|> "contact" $> CMContact
+
+instance ConnectionModeI m => FromJSON (ConnectionRequestUri m) where
+  parseJSON = strParseJSON "ConnectionRequestUri"
+
+instance ConnectionModeI m => ToJSON (ConnectionRequestUri m) where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+instance FromJSON AConnectionRequestUri where
+  parseJSON = strParseJSON "ConnectionRequestUri"
+
+instance ToJSON AConnectionRequestUri where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+-- debug :: Show a => String -> a -> a
+-- debug name value = unsafePerformIO (putStrLn $ name <> ": " <> show value) `seq` value
+-- {-# INLINE debug #-}
+
+instance StrEncoding ConnectionMode where
+  strEncode = \case
+    CMInvitation -> "INV"
+    CMContact -> "CON"
+  strP = "INV" $> CMInvitation <|> "CON" $> CMContact
+
+instance StrEncoding AConnectionMode where
+  strEncode (ACM cMode) = strEncode $ connMode cMode
+  strP = connMode' <$> strP
+
+connModeT :: Text -> Maybe ConnectionMode
+connModeT = \case
+  "INV" -> Just CMInvitation
+  "CON" -> Just CMContact
+  _ -> Nothing
+
+-- | SMP agent connection ID.
+type ConnId = ByteString
+
+type ConfirmationId = ByteString
+
+type InvitationId = ByteString
+
+data SMPQueueInfo = SMPQueueInfo
+  { clientVersion :: Version,
+    smpServer :: SMPServer,
+    senderId :: SMP.SenderId,
+    dhPublicKey :: C.PublicKeyX25519
+  }
+  deriving (Eq, Show)
+
+instance Encoding SMPQueueInfo where
+  smpEncode SMPQueueInfo {clientVersion, smpServer, senderId, dhPublicKey} =
+    smpEncode (clientVersion, smpServer, senderId, dhPublicKey)
+  smpP = do
+    (clientVersion, smpServer, senderId, dhPublicKey) <- smpP
+    pure SMPQueueInfo {clientVersion, smpServer, senderId, dhPublicKey}
+
+-- This instance seems contrived and there was a temptation to split a common part of both types.
+-- But this is created to allow backward and forward compatibility where SMPQueueUri
+-- could have more fields to convert to different versions of SMPQueueInfo in a different way,
+-- and this instance would become non-trivial.
+instance VersionI SMPQueueInfo where
+  type VersionRangeT SMPQueueInfo = SMPQueueUri
+  version = clientVersion
+  toVersionRangeT SMPQueueInfo {smpServer, senderId, dhPublicKey} vr =
+    SMPQueueUri {clientVRange = vr, smpServer, senderId, dhPublicKey}
+
+instance VersionRangeI SMPQueueUri where
+  type VersionT SMPQueueUri = SMPQueueInfo
+  versionRange = clientVRange
+  toVersionT SMPQueueUri {smpServer, senderId, dhPublicKey} v =
+    SMPQueueInfo {clientVersion = v, smpServer, senderId, dhPublicKey}
+
+-- | SMP queue information sent out-of-band.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#out-of-band-messages
+data SMPQueueUri = SMPQueueUri
+  { smpServer :: SMPServer,
+    senderId :: SMP.SenderId,
+    clientVRange :: VersionRange,
+    dhPublicKey :: C.PublicKeyX25519
+  }
+  deriving (Eq, Show)
+
+instance StrEncoding SMPQueueUri where
+  -- v1 uses short SMP queue URI format
+  strEncode SMPQueueUri {smpServer = srv, senderId = qId, clientVRange = _vr, dhPublicKey = k} =
+    strEncode srv <> "/" <> strEncode qId <> "#" <> strEncode k
+  strP = do
+    smpServer <- strP <* A.char '/'
+    senderId <- strP <* optional (A.char '/') <* A.char '#'
+    (vr, dhPublicKey) <- unversioned <|> versioned
+    pure SMPQueueUri {smpServer, senderId, clientVRange = vr, dhPublicKey}
+    where
+      unversioned = (SMP.smpClientVRange,) <$> strP <* A.endOfInput
+      versioned = do
+        dhKey_ <- optional strP
+        query <- optional (A.char '/') *> A.char '?' *> strP
+        vr <- queryParam "v" query
+        dhKey <- maybe (queryParam "dh" query) pure dhKey_
+        pure (vr, dhKey)
+
+data ConnectionRequestUri (m :: ConnectionMode) where
+  CRInvitationUri :: ConnReqUriData -> E2ERatchetParamsUri 'C.X448 -> ConnectionRequestUri CMInvitation
+  -- contact connection request does NOT contain E2E encryption parameters -
+  -- they are passed in AgentInvitation message
+  CRContactUri :: ConnReqUriData -> ConnectionRequestUri CMContact
+
+deriving instance Eq (ConnectionRequestUri m)
+
+deriving instance Show (ConnectionRequestUri m)
+
+data AConnectionRequestUri = forall m. ConnectionModeI m => ACR (SConnectionMode m) (ConnectionRequestUri m)
+
+instance Eq AConnectionRequestUri where
+  ACR m cr == ACR m' cr' = case testEquality m m' of
+    Just Refl -> cr == cr'
+    _ -> False
+
+deriving instance Show AConnectionRequestUri
+
+data ConnReqUriData = ConnReqUriData
+  { crScheme :: ConnReqScheme,
+    crAgentVRange :: VersionRange,
+    crSmpQueues :: L.NonEmpty SMPQueueUri
+  }
+  deriving (Eq, Show)
+
+data ConnReqScheme = CRSSimplex | CRSAppServer SrvLoc
+  deriving (Eq, Show)
+
+instance StrEncoding ConnReqScheme where
+  strEncode = \case
+    CRSSimplex -> "simplex:"
+    CRSAppServer srv -> "https://" <> strEncode srv
+  strP =
+    "simplex:" $> CRSSimplex
+      <|> "https://" *> (CRSAppServer <$> strP)
+
+simplexChat :: ConnReqScheme
+simplexChat = CRSAppServer $ SrvLoc "simplex.chat" ""
+
+-- | SMP queue status.
+data QueueStatus
+  = -- | queue is created
+    New
+  | -- | queue is confirmed by the sender
+    Confirmed
+  | -- | queue is secured with sender key (only used by the queue recipient)
+    Secured
+  | -- | queue is active
+    Active
+  | -- | queue is disabled (only used by the queue recipient)
+    Disabled
+  deriving (Eq, Show, Read)
+
+serializeQueueStatus :: QueueStatus -> Text
+serializeQueueStatus = \case
+  New -> "new"
+  Confirmed -> "confirmed"
+  Secured -> "secured"
+  Active -> "active"
+  Disabled -> "disabled"
+
+queueStatusT :: Text -> Maybe QueueStatus
+queueStatusT = \case
+  "new" -> Just New
+  "confirmed" -> Just Confirmed
+  "secured" -> Just Secured
+  "active" -> Just Active
+  "disabled" -> Just Disabled
+  _ -> Nothing
+
+type AgentMsgId = Int64
+
+-- | Result of received message integrity validation.
+data MsgIntegrity = MsgOk | MsgError {errorInfo :: MsgErrorType}
+  deriving (Eq, Show, Generic)
+
+instance StrEncoding MsgIntegrity where
+  strP = "OK" $> MsgOk <|> "ERR " *> (MsgError <$> strP)
+  strEncode = \case
+    MsgOk -> "OK"
+    MsgError e -> "ERR" <> strEncode e
+
+instance ToJSON MsgIntegrity where
+  toJSON = J.genericToJSON $ sumTypeJSON fstToLower
+  toEncoding = J.genericToEncoding $ sumTypeJSON fstToLower
+
+instance FromJSON MsgIntegrity where
+  parseJSON = J.genericParseJSON $ sumTypeJSON fstToLower
+
+-- | Error of message integrity validation.
+data MsgErrorType
+  = MsgSkipped {fromMsgId :: AgentMsgId, toMsgId :: AgentMsgId}
+  | MsgBadId {msgId :: AgentMsgId}
+  | MsgBadHash
+  | MsgDuplicate
+  deriving (Eq, Show, Generic)
+
+instance StrEncoding MsgErrorType where
+  strP =
+    "ID " *> (MsgBadId <$> A.decimal)
+      <|> "IDS " *> (MsgSkipped <$> A.decimal <* A.space <*> A.decimal)
+      <|> "HASH" $> MsgBadHash
+      <|> "DUPLICATE" $> MsgDuplicate
+  strEncode = \case
+    MsgSkipped fromMsgId toMsgId ->
+      B.unwords ["NO_ID", bshow fromMsgId, bshow toMsgId]
+    MsgBadId aMsgId -> "ID " <> bshow aMsgId
+    MsgBadHash -> "HASH"
+    MsgDuplicate -> "DUPLICATE"
+
+instance ToJSON MsgErrorType where
+  toJSON = J.genericToJSON $ sumTypeJSON fstToLower
+  toEncoding = J.genericToEncoding $ sumTypeJSON fstToLower
+
+instance FromJSON MsgErrorType where
+  parseJSON = J.genericParseJSON $ sumTypeJSON fstToLower
+
+-- | Error type used in errors sent to agent clients.
+data AgentErrorType
+  = -- | command or response error
+    CMD {cmdErr :: CommandErrorType}
+  | -- | connection errors
+    CONN {connErr :: ConnectionErrorType}
+  | -- | SMP protocol errors forwarded to agent clients
+    SMP {smpErr :: ErrorType}
+  | -- | NTF protocol errors forwarded to agent clients
+    NTF {ntfErr :: ErrorType}
+  | -- | SMP server errors
+    BROKER {brokerErr :: BrokerErrorType}
+  | -- | errors of other agents
+    AGENT {agentErr :: SMPAgentError}
+  | -- | agent implementation or dependency errors
+    INTERNAL {internalErr :: String}
+  deriving (Eq, Generic, Read, Show, Exception)
+
+instance ToJSON AgentErrorType where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+-- | SMP agent protocol command or response error.
+data CommandErrorType
+  = -- | command is prohibited in this context
+    PROHIBITED
+  | -- | command syntax is invalid
+    SYNTAX
+  | -- | entity ID is required with this command
+    NO_CONN
+  | -- | message size is not correct (no terminating space)
+    SIZE
+  | -- | message does not fit in SMP block
+    LARGE
+  deriving (Eq, Generic, Read, Show, Exception)
+
+instance ToJSON CommandErrorType where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+-- | Connection error.
+data ConnectionErrorType
+  = -- | connection is not in the database
+    NOT_FOUND
+  | -- | connection already exists
+    DUPLICATE
+  | -- | connection is simplex, but operation requires another queue
+    SIMPLEX
+  | -- | connection not accepted on join HELLO after timeout
+    NOT_ACCEPTED
+  | -- | connection not available on reply confirmation/HELLO after timeout
+    NOT_AVAILABLE
+  deriving (Eq, Generic, Read, Show, Exception)
+
+instance ToJSON ConnectionErrorType where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+-- | SMP server errors.
+data BrokerErrorType
+  = -- | invalid server response (failed to parse)
+    RESPONSE {smpErr :: ErrorType}
+  | -- | unexpected response
+    UNEXPECTED
+  | -- | network error
+    NETWORK
+  | -- | handshake or other transport error
+    TRANSPORT {transportErr :: TransportError}
+  | -- | command response timeout
+    TIMEOUT
+  deriving (Eq, Generic, Read, Show, Exception)
+
+instance ToJSON BrokerErrorType where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+-- | Errors of another SMP agent.
+-- TODO encode/decode without A prefix
+data SMPAgentError
+  = -- | client or agent message that failed to parse
+    A_MESSAGE
+  | -- | prohibited SMP/agent message
+    A_PROHIBITED
+  | -- | incompatible version of SMP client, agent or encryption protocols
+    A_VERSION
+  | -- | cannot decrypt message
+    A_ENCRYPTION
+  deriving (Eq, Generic, Read, Show, Exception)
+
+instance ToJSON SMPAgentError where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+instance StrEncoding AgentErrorType where
+  strP =
+    "CMD " *> (CMD <$> parseRead1)
+      <|> "CONN " *> (CONN <$> parseRead1)
+      <|> "SMP " *> (SMP <$> strP)
+      <|> "NTF " *> (NTF <$> strP)
+      <|> "BROKER RESPONSE " *> (BROKER . RESPONSE <$> strP)
+      <|> "BROKER TRANSPORT " *> (BROKER . TRANSPORT <$> transportErrorP)
+      <|> "BROKER " *> (BROKER <$> parseRead1)
+      <|> "AGENT " *> (AGENT <$> parseRead1)
+      <|> "INTERNAL " *> (INTERNAL <$> parseRead A.takeByteString)
+  strEncode = \case
+    CMD e -> "CMD " <> bshow e
+    CONN e -> "CONN " <> bshow e
+    SMP e -> "SMP " <> strEncode e
+    NTF e -> "NTF " <> strEncode e
+    BROKER (RESPONSE e) -> "BROKER RESPONSE " <> strEncode e
+    BROKER (TRANSPORT e) -> "BROKER TRANSPORT " <> serializeTransportError e
+    BROKER e -> "BROKER " <> bshow e
+    AGENT e -> "AGENT " <> bshow e
+    INTERNAL e -> "INTERNAL " <> bshow e
+
+instance Arbitrary AgentErrorType where arbitrary = genericArbitraryU
+
+instance Arbitrary CommandErrorType where arbitrary = genericArbitraryU
+
+instance Arbitrary ConnectionErrorType where arbitrary = genericArbitraryU
+
+instance Arbitrary BrokerErrorType where arbitrary = genericArbitraryU
+
+instance Arbitrary SMPAgentError where arbitrary = genericArbitraryU
+
+-- | SMP agent command and response parser
+commandP :: Parser ACmd
+commandP =
+  "NEW " *> newCmd
+    <|> "INV " *> invResp
+    <|> "JOIN " *> joinCmd
+    <|> "CONF " *> confMsg
+    <|> "LET " *> letCmd
+    <|> "REQ " *> reqMsg
+    <|> "ACPT " *> acptCmd
+    <|> "RJCT " *> rjctCmd
+    <|> "INFO " *> infoCmd
+    <|> "SUB" $> ACmd SClient SUB
+    <|> "END" $> ACmd SAgent END
+    <|> "DOWN " *> downsResp
+    <|> "UP " *> upsResp
+    <|> "SEND " *> sendCmd
+    <|> "MID " *> msgIdResp
+    <|> "SENT " *> sentResp
+    <|> "MERR " *> msgErrResp
+    <|> "MSG " *> message
+    <|> "ACK " *> ackCmd
+    <|> "OFF" $> ACmd SClient OFF
+    <|> "DEL" $> ACmd SClient DEL
+    <|> "ERR " *> agentError
+    <|> "CON" $> ACmd SAgent CON
+    <|> "OK" $> ACmd SAgent OK
+  where
+    newCmd = ACmd SClient . NEW <$> strP
+    invResp = ACmd SAgent . INV <$> strP
+    joinCmd = ACmd SClient .: JOIN <$> strP_ <*> A.takeByteString
+    confMsg = ACmd SAgent .: CONF <$> A.takeTill (== ' ') <* A.space <*> A.takeByteString
+    letCmd = ACmd SClient .: LET <$> A.takeTill (== ' ') <* A.space <*> A.takeByteString
+    reqMsg = ACmd SAgent .: REQ <$> A.takeTill (== ' ') <* A.space <*> A.takeByteString
+    acptCmd = ACmd SClient .: ACPT <$> A.takeTill (== ' ') <* A.space <*> A.takeByteString
+    rjctCmd = ACmd SClient . RJCT <$> A.takeByteString
+    infoCmd = ACmd SAgent . INFO <$> A.takeByteString
+    downsResp = ACmd SAgent .: DOWN <$> strP <* A.space <*> connections
+    upsResp = ACmd SAgent .: UP <$> strP <* A.space <*> connections
+    sendCmd = ACmd SClient . SEND <$> A.takeByteString
+    msgIdResp = ACmd SAgent . MID <$> A.decimal
+    sentResp = ACmd SAgent . SENT <$> A.decimal
+    msgErrResp = ACmd SAgent .: MERR <$> A.decimal <* A.space <*> strP
+    message = ACmd SAgent .: MSG <$> msgMetaP <* A.space <*> A.takeByteString
+    ackCmd = ACmd SClient . ACK <$> A.decimal
+    connections = strP `A.sepBy'` (A.char ',')
+    msgMetaP = do
+      integrity <- strP
+      recipient <- " R=" *> partyMeta A.decimal
+      broker <- " B=" *> partyMeta base64P
+      sndMsgId <- " S=" *> A.decimal
+      pure MsgMeta {integrity, recipient, broker, sndMsgId}
+    partyMeta idParser = (,) <$> idParser <* A.char ',' <*> tsISO8601P
+    agentError = ACmd SAgent . ERR <$> strP
+
+parseCommand :: ByteString -> Either AgentErrorType ACmd
+parseCommand = parse commandP $ CMD SYNTAX
+
+-- | Serialize SMP agent command.
+serializeCommand :: ACommand p -> ByteString
+serializeCommand = \case
+  NEW cMode -> "NEW " <> strEncode cMode
+  INV cReq -> "INV " <> strEncode cReq
+  JOIN cReq cInfo -> B.unwords ["JOIN", strEncode cReq, serializeBinary cInfo]
+  CONF confId cInfo -> B.unwords ["CONF", confId, serializeBinary cInfo]
+  LET confId cInfo -> B.unwords ["LET", confId, serializeBinary cInfo]
+  REQ invId cInfo -> B.unwords ["REQ", invId, serializeBinary cInfo]
+  ACPT invId cInfo -> B.unwords ["ACPT", invId, serializeBinary cInfo]
+  RJCT invId -> "RJCT " <> invId
+  INFO cInfo -> "INFO " <> serializeBinary cInfo
+  SUB -> "SUB"
+  END -> "END"
+  DOWN srv conns -> B.unwords ["DOWN", strEncode srv, connections conns]
+  UP srv conns -> B.unwords ["UP", strEncode srv, connections conns]
+  SEND msgBody -> "SEND " <> serializeBinary msgBody
+  MID mId -> "MID " <> bshow mId
+  SENT mId -> "SENT " <> bshow mId
+  MERR mId e -> B.unwords ["MERR", bshow mId, strEncode e]
+  MSG msgMeta msgBody -> B.unwords ["MSG", serializeMsgMeta msgMeta, serializeBinary msgBody]
+  ACK mId -> "ACK " <> bshow mId
+  OFF -> "OFF"
+  DEL -> "DEL"
+  CON -> "CON"
+  ERR e -> "ERR " <> strEncode e
+  OK -> "OK"
+  where
+    showTs :: UTCTime -> ByteString
+    showTs = B.pack . formatISO8601Millis
+    connections :: [ConnId] -> ByteString
+    connections = B.intercalate "," . map strEncode
+    serializeMsgMeta :: MsgMeta -> ByteString
+    serializeMsgMeta MsgMeta {integrity, recipient = (rmId, rTs), broker = (bmId, bTs), sndMsgId} =
+      B.unwords
+        [ strEncode integrity,
+          "R=" <> bshow rmId <> "," <> showTs rTs,
+          "B=" <> encode bmId <> "," <> showTs bTs,
+          "S=" <> bshow sndMsgId
+        ]
+
+serializeBinary :: ByteString -> ByteString
+serializeBinary body = bshow (B.length body) <> "\n" <> body
+
+-- | Send raw (unparsed) SMP agent protocol transmission to TCP connection.
+tPutRaw :: Transport c => c -> ARawTransmission -> IO ()
+tPutRaw h (corrId, entity, command) = do
+  putLn h corrId
+  putLn h entity
+  putLn h command
+
+-- | Receive raw (unparsed) SMP agent protocol transmission from TCP connection.
+tGetRaw :: Transport c => c -> IO ARawTransmission
+tGetRaw h = (,,) <$> getLn h <*> getLn h <*> getLn h
+
+-- | Send SMP agent protocol command (or response) to TCP connection.
+tPut :: (Transport c, MonadIO m) => c -> ATransmission p -> m ()
+tPut h (corrId, connId, command) =
+  liftIO $ tPutRaw h (corrId, connId, serializeCommand command)
+
+-- | Receive client and agent transmissions from TCP connection.
+tGet :: forall c m p. (Transport c, MonadIO m) => SAParty p -> c -> m (ATransmissionOrError p)
+tGet party h = liftIO (tGetRaw h) >>= tParseLoadBody
+  where
+    tParseLoadBody :: ARawTransmission -> m (ATransmissionOrError p)
+    tParseLoadBody t@(corrId, connId, command) = do
+      let cmd = parseCommand command >>= fromParty >>= tConnId t
+      fullCmd <- either (return . Left) cmdWithMsgBody cmd
+      return (corrId, connId, fullCmd)
+
+    fromParty :: ACmd -> Either AgentErrorType (ACommand p)
+    fromParty (ACmd (p :: p1) cmd) = case testEquality party p of
+      Just Refl -> Right cmd
+      _ -> Left $ CMD PROHIBITED
+
+    tConnId :: ARawTransmission -> ACommand p -> Either AgentErrorType (ACommand p)
+    tConnId (_, connId, _) cmd = case cmd of
+      -- NEW, JOIN and ACPT have optional connId
+      NEW _ -> Right cmd
+      JOIN {} -> Right cmd
+      ACPT {} -> Right cmd
+      -- ERROR response does not always have connId
+      ERR _ -> Right cmd
+      DOWN {} -> Right cmd
+      UP {} -> Right cmd
+      -- other responses must have connId
+      _
+        | B.null connId -> Left $ CMD NO_CONN
+        | otherwise -> Right cmd
+
+    cmdWithMsgBody :: ACommand p -> m (Either AgentErrorType (ACommand p))
+    cmdWithMsgBody = \case
+      SEND body -> SEND <$$> getBody body
+      MSG msgMeta body -> MSG msgMeta <$$> getBody body
+      JOIN qUri cInfo -> JOIN qUri <$$> getBody cInfo
+      CONF confId cInfo -> CONF confId <$$> getBody cInfo
+      LET confId cInfo -> LET confId <$$> getBody cInfo
+      REQ invId cInfo -> REQ invId <$$> getBody cInfo
+      ACPT invId cInfo -> ACPT invId <$$> getBody cInfo
+      INFO cInfo -> INFO <$$> getBody cInfo
+      cmd -> pure $ Right cmd
+
+    getBody :: ByteString -> m (Either AgentErrorType ByteString)
+    getBody binary =
+      case B.unpack binary of
+        ':' : body -> return . Right $ B.pack body
+        str -> case readMaybe str :: Maybe Int of
+          Just size -> liftIO $ do
+            body <- cGet h size
+            s <- getLn h
+            return $ if B.null s then Right body else Left $ CMD SIZE
+          Nothing -> return . Left $ CMD SYNTAX

src/Simplex/Messaging/Agent/QueryString.hs

@@ -0,0 +1,30 @@
+module Simplex.Messaging.Agent.QueryString where
+
+import Data.Attoparsec.ByteString.Char8 (Parser)
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.List (find)
+import qualified Network.HTTP.Types as Q
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Parsers (parseAll)
+
+data QueryStringParams = QSP QSPEscaping Q.SimpleQuery
+  deriving (Show)
+
+data QSPEscaping = QEscape | QNoEscaping
+  deriving (Show)
+
+instance StrEncoding QueryStringParams where
+  strEncode (QSP esc q) = case esc of
+    QEscape -> Q.renderSimpleQuery False q
+    QNoEscaping ->
+      Q.renderQueryPartialEscape False $
+        map (\(n, v) -> (n, [Q.QN v])) q
+  strP = QSP QEscape . Q.parseSimpleQuery <$> A.takeTill (\c -> c == ' ' || c == '\n')
+
+queryParam :: StrEncoding a => ByteString -> QueryStringParams -> Parser a
+queryParam name (QSP _ q) =
+  case find ((== name) . fst) q of
+    Just (_, p) -> either fail pure $ parseAll strP p
+    _ -> fail $ "no qs param " <> B.unpack name

src/Simplex/Messaging/Agent/RetryInterval.hs

@@ -0,0 +1,28 @@
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Simplex.Messaging.Agent.RetryInterval where
+
+import Control.Concurrent (threadDelay)
+import Control.Monad.IO.Class (MonadIO, liftIO)
+
+data RetryInterval = RetryInterval
+  { initialInterval :: Int,
+    increaseAfter :: Int,
+    maxInterval :: Int
+  }
+
+withRetryInterval :: forall m. MonadIO m => RetryInterval -> (m () -> m ()) -> m ()
+withRetryInterval RetryInterval {initialInterval, increaseAfter, maxInterval} action =
+  callAction 0 initialInterval
+  where
+    callAction :: Int -> Int -> m ()
+    callAction elapsedTime delay = action loop
+      where
+        loop = do
+          let newDelay =
+                if elapsedTime < increaseAfter || delay == maxInterval
+                  then delay
+                  else min (delay * 3 `div` 2) maxInterval
+          liftIO $ threadDelay delay
+          callAction (elapsedTime + delay) newDelay

src/Simplex/Messaging/Agent/Server.hs

@@ -0,0 +1,81 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Simplex.Messaging.Agent.Server
+  ( -- * SMP agent over TCP
+    runSMPAgent,
+    runSMPAgentBlocking,
+  )
+where
+
+import Control.Logger.Simple (logInfo)
+import Control.Monad.Except
+import Control.Monad.IO.Unlift (MonadUnliftIO)
+import Control.Monad.Reader
+import Crypto.Random (MonadRandom)
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Text.Encoding (decodeUtf8)
+import Simplex.Messaging.Agent
+import Simplex.Messaging.Agent.Env.SQLite
+import Simplex.Messaging.Agent.Protocol
+import Simplex.Messaging.Transport (ATransport (..), TProxy, Transport (..), simplexMQVersion)
+import Simplex.Messaging.Transport.Server (loadTLSServerParams, runTransportServer)
+import Simplex.Messaging.Util (bshow)
+import UnliftIO.Async (race_)
+import qualified UnliftIO.Exception as E
+import UnliftIO.STM
+
+-- | Runs an SMP agent as a TCP service using passed configuration.
+--
+-- See a full agent executable here: https://github.com/simplex-chat/simplexmq/blob/master/apps/smp-agent/Main.hs
+runSMPAgent :: (MonadRandom m, MonadUnliftIO m) => ATransport -> AgentConfig -> InitialAgentServers -> m ()
+runSMPAgent t cfg initServers = do
+  started <- newEmptyTMVarIO
+  runSMPAgentBlocking t started cfg initServers
+
+-- | Runs an SMP agent as a TCP service using passed configuration with signalling.
+--
+-- This function uses passed TMVar to signal when the server is ready to accept TCP requests (True)
+-- and when it is disconnected from the TCP socket once the server thread is killed (False).
+runSMPAgentBlocking :: (MonadRandom m, MonadUnliftIO m) => ATransport -> TMVar Bool -> AgentConfig -> InitialAgentServers -> m ()
+runSMPAgentBlocking (ATransport t) started cfg@AgentConfig {tcpPort, caCertificateFile, certificateFile, privateKeyFile} initServers = do
+  runReaderT (smpAgent t) =<< newSMPAgentEnv cfg
+  where
+    smpAgent :: forall c m'. (Transport c, MonadUnliftIO m', MonadReader Env m') => TProxy c -> m' ()
+    smpAgent _ = do
+      -- tlsServerParams is not in Env to avoid breaking functional API w/t key and certificate generation
+      tlsServerParams <- liftIO $ loadTLSServerParams caCertificateFile certificateFile privateKeyFile
+      runTransportServer started tcpPort tlsServerParams $ \(h :: c) -> do
+        liftIO . putLn h $ "Welcome to SMP agent v" <> B.pack simplexMQVersion
+        c <- getAgentClient initServers
+        logConnection c True
+        race_ (connectClient h c) (runAgentClient c)
+          `E.finally` disconnectAgentClient c
+
+connectClient :: Transport c => MonadUnliftIO m => c -> AgentClient -> m ()
+connectClient h c = race_ (send h c) (receive h c)
+
+receive :: forall c m. (Transport c, MonadUnliftIO m) => c -> AgentClient -> m ()
+receive h c@AgentClient {rcvQ, subQ} = forever $ do
+  (corrId, connId, cmdOrErr) <- tGet SClient h
+  case cmdOrErr of
+    Right cmd -> write rcvQ (corrId, connId, cmd)
+    Left e -> write subQ (corrId, connId, ERR e)
+  where
+    write :: TBQueue (ATransmission p) -> ATransmission p -> m ()
+    write q t = do
+      logClient c "-->" t
+      atomically $ writeTBQueue q t
+
+send :: (Transport c, MonadUnliftIO m) => c -> AgentClient -> m ()
+send h c@AgentClient {subQ} = forever $ do
+  t <- atomically $ readTBQueue subQ
+  tPut h t
+  logClient c "<--" t
+
+logClient :: MonadUnliftIO m => AgentClient -> ByteString -> ATransmission a -> m ()
+logClient AgentClient {clientId} dir (corrId, connId, cmd) = do
+  logInfo . decodeUtf8 $ B.unwords [bshow clientId, dir, "A :", corrId, connId, B.takeWhile (/= ' ') $ serializeCommand cmd]

src/Simplex/Messaging/Agent/Store.hs

@@ -0,0 +1,324 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}
+
+module Simplex.Messaging.Agent.Store where
+
+import Control.Concurrent.STM (TVar)
+import Control.Exception (Exception)
+import Crypto.Random (ChaChaDRG)
+import Data.ByteString.Char8 (ByteString)
+import Data.Int (Int64)
+import Data.Kind (Type)
+import Data.Time (UTCTime)
+import Data.Type.Equality
+import Simplex.Messaging.Agent.Protocol
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Crypto.Ratchet (RatchetX448, SkippedMsgDiff, SkippedMsgKeys)
+import Simplex.Messaging.Notifications.Client
+import Simplex.Messaging.Notifications.Protocol (DeviceToken, NtfTknStatus, NtfTokenId)
+import Simplex.Messaging.Protocol
+  ( MsgBody,
+    MsgId,
+    RcvDhSecret,
+    RcvPrivateSignKey,
+    SndPrivateSignKey,
+  )
+import qualified Simplex.Messaging.Protocol as SMP
+
+-- * Store management
+
+-- | Store class type. Defines store access methods for implementations.
+class Monad m => MonadAgentStore s m where
+  -- Queue and Connection management
+  createRcvConn :: s -> TVar ChaChaDRG -> ConnData -> RcvQueue -> SConnectionMode c -> m ConnId
+  createSndConn :: s -> TVar ChaChaDRG -> ConnData -> SndQueue -> m ConnId
+  getConn :: s -> ConnId -> m SomeConn
+  getRcvConn :: s -> SMPServer -> SMP.RecipientId -> m SomeConn
+  deleteConn :: s -> ConnId -> m ()
+  upgradeRcvConnToDuplex :: s -> ConnId -> SndQueue -> m ()
+  upgradeSndConnToDuplex :: s -> ConnId -> RcvQueue -> m ()
+  setRcvQueueStatus :: s -> RcvQueue -> QueueStatus -> m ()
+  setRcvQueueConfirmedE2E :: s -> RcvQueue -> C.DhSecretX25519 -> m ()
+  setSndQueueStatus :: s -> SndQueue -> QueueStatus -> m ()
+
+  -- Confirmations
+  createConfirmation :: s -> TVar ChaChaDRG -> NewConfirmation -> m ConfirmationId
+  acceptConfirmation :: s -> ConfirmationId -> ConnInfo -> m AcceptedConfirmation
+  getAcceptedConfirmation :: s -> ConnId -> m AcceptedConfirmation
+  removeConfirmations :: s -> ConnId -> m ()
+
+  -- Invitations - sent via Contact connections
+  createInvitation :: s -> TVar ChaChaDRG -> NewInvitation -> m InvitationId
+  getInvitation :: s -> InvitationId -> m Invitation
+  acceptInvitation :: s -> InvitationId -> ConnInfo -> m ()
+  deleteInvitation :: s -> ConnId -> InvitationId -> m ()
+
+  -- Msg management
+  updateRcvIds :: s -> ConnId -> m (InternalId, InternalRcvId, PrevExternalSndId, PrevRcvMsgHash)
+  createRcvMsg :: s -> ConnId -> RcvMsgData -> m ()
+  updateSndIds :: s -> ConnId -> m (InternalId, InternalSndId, PrevSndMsgHash)
+  createSndMsg :: s -> ConnId -> SndMsgData -> m ()
+  getPendingMsgData :: s -> ConnId -> InternalId -> m (Maybe RcvQueue, (AgentMessageType, MsgBody, InternalTs))
+  getPendingMsgs :: s -> ConnId -> m [InternalId]
+  checkRcvMsg :: s -> ConnId -> InternalId -> m ()
+  deleteMsg :: s -> ConnId -> InternalId -> m ()
+
+  -- Double ratchet persistence
+  createRatchetX3dhKeys :: s -> ConnId -> C.PrivateKeyX448 -> C.PrivateKeyX448 -> m ()
+  getRatchetX3dhKeys :: s -> ConnId -> m (C.PrivateKeyX448, C.PrivateKeyX448)
+  createRatchet :: s -> ConnId -> RatchetX448 -> m ()
+  getRatchet :: s -> ConnId -> m RatchetX448
+  getSkippedMsgKeys :: s -> ConnId -> m SkippedMsgKeys
+  updateRatchet :: s -> ConnId -> RatchetX448 -> SkippedMsgDiff -> m ()
+
+  -- Notification device token persistence
+  createNtfToken :: s -> NtfToken -> m ()
+
+  getDeviceNtfToken :: s -> DeviceToken -> m (Maybe NtfToken, [NtfToken])
+  updateNtfTokenRegistration :: s -> NtfToken -> NtfTokenId -> C.DhSecretX25519 -> m ()
+  updateNtfToken :: s -> NtfToken -> NtfTknStatus -> Maybe NtfTknAction -> m ()
+  removeNtfToken :: s -> NtfToken -> m ()
+
+-- * Queue types
+
+-- | A receive queue. SMP queue through which the agent receives messages from a sender.
+data RcvQueue = RcvQueue
+  { server :: SMPServer,
+    -- | recipient queue ID
+    rcvId :: SMP.RecipientId,
+    -- | key used by the recipient to sign transmissions
+    rcvPrivateKey :: RcvPrivateSignKey,
+    -- | shared DH secret used to encrypt/decrypt message bodies from server to recipient
+    rcvDhSecret :: RcvDhSecret,
+    -- | private DH key related to public sent to sender out-of-band (to agree simple per-queue e2e)
+    e2ePrivKey :: C.PrivateKeyX25519,
+    -- | public sender's DH key and agreed shared DH secret for simple per-queue e2e
+    e2eDhSecret :: Maybe C.DhSecretX25519,
+    -- | sender queue ID
+    sndId :: Maybe SMP.SenderId,
+    -- | queue status
+    status :: QueueStatus
+  }
+  deriving (Eq, Show)
+
+-- | A send queue. SMP queue through which the agent sends messages to a recipient.
+data SndQueue = SndQueue
+  { server :: SMPServer,
+    -- | sender queue ID
+    sndId :: SMP.SenderId,
+    -- | key pair used by the sender to sign transmissions
+    sndPublicKey :: Maybe C.APublicVerifyKey,
+    sndPrivateKey :: SndPrivateSignKey,
+    -- | DH public key used to negotiate per-queue e2e encryption
+    e2ePubKey :: Maybe C.PublicKeyX25519,
+    -- | shared DH secret agreed for simple per-queue e2e encryption
+    e2eDhSecret :: C.DhSecretX25519,
+    -- | queue status
+    status :: QueueStatus
+  }
+  deriving (Eq, Show)
+
+-- * Connection types
+
+-- | Type of a connection.
+data ConnType = CRcv | CSnd | CDuplex | CContact deriving (Eq, Show)
+
+-- | Connection of a specific type.
+--
+-- - RcvConnection is a connection that only has a receive queue set up,
+--   typically created by a recipient initiating a duplex connection.
+--
+-- - SndConnection is a connection that only has a send queue set up, typically
+--   created by a sender joining a duplex connection through a recipient's invitation.
+--
+-- - DuplexConnection is a connection that has both receive and send queues set up,
+--   typically created by upgrading a receive or a send connection with a missing queue.
+data Connection (d :: ConnType) where
+  RcvConnection :: ConnData -> RcvQueue -> Connection CRcv
+  SndConnection :: ConnData -> SndQueue -> Connection CSnd
+  DuplexConnection :: ConnData -> RcvQueue -> SndQueue -> Connection CDuplex
+  ContactConnection :: ConnData -> RcvQueue -> Connection CContact
+
+deriving instance Eq (Connection d)
+
+deriving instance Show (Connection d)
+
+data SConnType :: ConnType -> Type where
+  SCRcv :: SConnType CRcv
+  SCSnd :: SConnType CSnd
+  SCDuplex :: SConnType CDuplex
+  SCContact :: SConnType CContact
+
+connType :: SConnType c -> ConnType
+connType SCRcv = CRcv
+connType SCSnd = CSnd
+connType SCDuplex = CDuplex
+connType SCContact = CContact
+
+deriving instance Eq (SConnType d)
+
+deriving instance Show (SConnType d)
+
+instance TestEquality SConnType where
+  testEquality SCRcv SCRcv = Just Refl
+  testEquality SCSnd SCSnd = Just Refl
+  testEquality SCDuplex SCDuplex = Just Refl
+  testEquality SCContact SCContact = Just Refl
+  testEquality _ _ = Nothing
+
+-- | Connection of an unknown type.
+-- Used to refer to an arbitrary connection when retrieving from store.
+data SomeConn = forall d. SomeConn (SConnType d) (Connection d)
+
+instance Eq SomeConn where
+  SomeConn d c == SomeConn d' c' = case testEquality d d' of
+    Just Refl -> c == c'
+    _ -> False
+
+deriving instance Show SomeConn
+
+newtype ConnData = ConnData {connId :: ConnId}
+  deriving (Eq, Show)
+
+-- * Confirmation types
+
+data NewConfirmation = NewConfirmation
+  { connId :: ConnId,
+    senderConf :: SMPConfirmation,
+    ratchetState :: RatchetX448
+  }
+
+data AcceptedConfirmation = AcceptedConfirmation
+  { confirmationId :: ConfirmationId,
+    connId :: ConnId,
+    senderConf :: SMPConfirmation,
+    ratchetState :: RatchetX448,
+    ownConnInfo :: ConnInfo
+  }
+
+-- * Invitations
+
+data NewInvitation = NewInvitation
+  { contactConnId :: ConnId,
+    connReq :: ConnectionRequestUri 'CMInvitation,
+    recipientConnInfo :: ConnInfo
+  }
+
+data Invitation = Invitation
+  { invitationId :: InvitationId,
+    contactConnId :: ConnId,
+    connReq :: ConnectionRequestUri 'CMInvitation,
+    recipientConnInfo :: ConnInfo,
+    ownConnInfo :: Maybe ConnInfo,
+    accepted :: Bool
+  }
+
+-- * Message integrity validation types
+
+-- | Corresponds to `last_external_snd_msg_id` in `connections` table
+type PrevExternalSndId = Int64
+
+-- | Corresponds to `last_rcv_msg_hash` in `connections` table
+type PrevRcvMsgHash = MsgHash
+
+-- | Corresponds to `last_snd_msg_hash` in `connections` table
+type PrevSndMsgHash = MsgHash
+
+-- * Message data containers - used on Msg creation to reduce number of parameters
+
+data RcvMsgData = RcvMsgData
+  { msgMeta :: MsgMeta,
+    msgType :: AgentMessageType,
+    msgBody :: MsgBody,
+    internalRcvId :: InternalRcvId,
+    internalHash :: MsgHash,
+    externalPrevSndHash :: MsgHash
+  }
+
+data SndMsgData = SndMsgData
+  { internalId :: InternalId,
+    internalSndId :: InternalSndId,
+    internalTs :: InternalTs,
+    msgType :: AgentMessageType,
+    msgBody :: MsgBody,
+    internalHash :: MsgHash,
+    prevMsgHash :: MsgHash
+  }
+
+data PendingMsg = PendingMsg
+  { connId :: ConnId,
+    msgId :: InternalId
+  }
+  deriving (Show)
+
+-- internal Ids are newtypes to prevent mixing them up
+newtype InternalRcvId = InternalRcvId {unRcvId :: Int64} deriving (Eq, Show)
+
+type ExternalSndId = Int64
+
+type ExternalSndTs = UTCTime
+
+type BrokerId = MsgId
+
+type BrokerTs = UTCTime
+
+newtype InternalSndId = InternalSndId {unSndId :: Int64} deriving (Eq, Show)
+
+-- | Base message data independent of direction.
+data MsgBase = MsgBase
+  { connId :: ConnId,
+    -- | Monotonically increasing id of a message per connection, internal to the agent.
+    -- Internal Id preserves ordering between both received and sent messages, and is needed
+    -- to track the order of the conversation (which can be different for the sender / receiver)
+    -- and address messages in commands. External [sender] Id cannot be used for this purpose
+    -- due to a possibility of implementation errors in different agents.
+    internalId :: InternalId,
+    internalTs :: InternalTs,
+    msgBody :: MsgBody,
+    -- | Hash of the message as computed by agent.
+    internalHash :: MsgHash
+  }
+  deriving (Eq, Show)
+
+newtype InternalId = InternalId {unId :: Int64} deriving (Eq, Show)
+
+type InternalTs = UTCTime
+
+-- * Store errors
+
+-- | Agent store error.
+data StoreError
+  = -- | IO exceptions in store actions.
+    SEInternal ByteString
+  | -- | Failed to generate unique random ID
+    SEUniqueID
+  | -- | Connection not found (or both queues absent).
+    SEConnNotFound
+  | -- | Connection already used.
+    SEConnDuplicate
+  | -- | Wrong connection type, e.g. "send" connection when "receive" or "duplex" is expected, or vice versa.
+    -- 'upgradeRcvConnToDuplex' and 'upgradeSndConnToDuplex' do not allow duplex connections - they would also return this error.
+    SEBadConnType ConnType
+  | -- | Confirmation not found.
+    SEConfirmationNotFound
+  | -- | Invitation not found
+    SEInvitationNotFound
+  | -- | Message not found
+    SEMsgNotFound
+  | -- | Currently not used. The intention was to pass current expected queue status in methods,
+    -- as we always know what it should be at any stage of the protocol,
+    -- and in case it does not match use this error.
+    SEBadQueueStatus
+  | -- | connection does not have associated double-ratchet state
+    SERatchetNotFound
+  | -- | connection does not have associated x3dh keys
+    SEX3dhKeysNotFound
+  | -- | Used in `getMsg` that is not implemented/used. TODO remove.
+    SENotImplemented
+  deriving (Eq, Show, Exception)

src/Simplex/Messaging/Agent/Store/SQLite/Migrations.hs

@@ -0,0 +1,76 @@
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE TupleSections #-}
+
+module Simplex.Messaging.Agent.Store.SQLite.Migrations
+  ( Migration (..),
+    app,
+    initialize,
+    get,
+    run,
+  )
+where
+
+import Control.Monad (forM_)
+import Data.Function (on)
+import Data.List (intercalate, sortBy)
+import Data.Text (Text)
+import Data.Time.Clock (getCurrentTime)
+import Database.SQLite.Simple (Connection, Only (..), Query (..))
+import qualified Database.SQLite.Simple as DB
+import Database.SQLite.Simple.QQ (sql)
+import qualified Database.SQLite3 as SQLite3
+import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220101_initial
+import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220301_snd_queue_keys
+import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220322_notifications
+
+data Migration = Migration {name :: String, up :: Text}
+  deriving (Show)
+
+schemaMigrations :: [(String, Query)]
+schemaMigrations =
+  [ ("20220101_initial", m20220101_initial),
+    ("20220301_snd_queue_keys", m20220301_snd_queue_keys),
+    ("20220322_notifications", m20220322_notifications)
+  ]
+
+-- | The list of migrations in ascending order by date
+app :: [Migration]
+app = sortBy (compare `on` name) $ map migration schemaMigrations
+  where
+    migration (name, query) = Migration {name = name, up = fromQuery query}
+
+get :: Connection -> [Migration] -> IO (Either String [Migration])
+get conn migrations =
+  migrationsToRun migrations . map fromOnly
+    <$> DB.query_ conn "SELECT name FROM migrations ORDER BY name ASC;"
+
+run :: Connection -> [Migration] -> IO ()
+run conn ms = DB.withImmediateTransaction conn . forM_ ms $
+  \Migration {name, up} -> insert name >> execSQL up
+  where
+    insert name = DB.execute conn "INSERT INTO migrations (name, ts) VALUES (?, ?);" . (name,) =<< getCurrentTime
+    execSQL = SQLite3.exec $ DB.connectionHandle conn
+
+initialize :: Connection -> IO ()
+initialize conn =
+  DB.execute_
+    conn
+    [sql|
+      CREATE TABLE IF NOT EXISTS migrations (
+        name TEXT NOT NULL,
+        ts TEXT NOT NULL,
+        PRIMARY KEY (name)
+      );
+    |]
+
+migrationsToRun :: [Migration] -> [String] -> Either String [Migration]
+migrationsToRun appMs [] = Right appMs
+migrationsToRun [] dbMs = Left $ "database version is newer than the app: " <> intercalate ", " dbMs
+migrationsToRun (a : as) (d : ds)
+  | name a == d = migrationsToRun as ds
+  | otherwise = Left $ "different migration in the app/database: " <> name a <> " / " <> d

src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20220101_initial.hs

@@ -0,0 +1,148 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220101_initial where
+
+import Database.SQLite.Simple (Query)
+import Database.SQLite.Simple.QQ (sql)
+
+m20220101_initial :: Query
+m20220101_initial =
+  [sql|
+CREATE TABLE servers (
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  key_hash BLOB NOT NULL,
+  PRIMARY KEY (host, port)
+) WITHOUT ROWID;
+
+CREATE TABLE connections (
+  conn_id BLOB NOT NULL PRIMARY KEY,
+  conn_mode TEXT NOT NULL,
+  last_internal_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_internal_rcv_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_internal_snd_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_external_snd_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_rcv_msg_hash BLOB NOT NULL DEFAULT x'',
+  last_snd_msg_hash BLOB NOT NULL DEFAULT x'',
+  smp_agent_version INTEGER NOT NULL DEFAULT 1
+) WITHOUT ROWID;
+
+CREATE TABLE rcv_queues (
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  rcv_id BLOB NOT NULL,
+  conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  rcv_private_key BLOB NOT NULL,
+  rcv_dh_secret BLOB NOT NULL,
+  e2e_priv_key BLOB NOT NULL,
+  e2e_dh_secret BLOB,
+  snd_id BLOB NOT NULL,
+  snd_key BLOB,
+  status TEXT NOT NULL,
+  smp_server_version INTEGER NOT NULL DEFAULT 1,
+  smp_client_version INTEGER,
+  PRIMARY KEY (host, port, rcv_id),
+  FOREIGN KEY (host, port) REFERENCES servers
+    ON DELETE RESTRICT ON UPDATE CASCADE,
+  UNIQUE (host, port, snd_id)
+) WITHOUT ROWID;
+
+CREATE TABLE snd_queues (
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  snd_id BLOB NOT NULL,
+  conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  snd_private_key BLOB NOT NULL,
+  e2e_dh_secret BLOB NOT NULL,
+  status TEXT NOT NULL,
+  smp_server_version INTEGER NOT NULL DEFAULT 1,
+  smp_client_version INTEGER NOT NULL DEFAULT 1,
+  PRIMARY KEY (host, port, snd_id),
+  FOREIGN KEY (host, port) REFERENCES servers
+    ON DELETE RESTRICT ON UPDATE CASCADE
+) WITHOUT ROWID;
+
+CREATE TABLE messages (
+  conn_id BLOB NOT NULL REFERENCES connections (conn_id)
+    ON DELETE CASCADE,
+  internal_id INTEGER NOT NULL,
+  internal_ts TEXT NOT NULL,
+  internal_rcv_id INTEGER,
+  internal_snd_id INTEGER,
+  msg_type BLOB NOT NULL, -- (H)ELLO, (R)EPLY, (D)ELETE. Should SMP confirmation be saved too?
+  msg_body BLOB NOT NULL DEFAULT x'',
+  PRIMARY KEY (conn_id, internal_id),
+  FOREIGN KEY (conn_id, internal_rcv_id) REFERENCES rcv_messages
+    ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED,
+  FOREIGN KEY (conn_id, internal_snd_id) REFERENCES snd_messages
+    ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED
+) WITHOUT ROWID;
+
+CREATE TABLE rcv_messages (
+  conn_id BLOB NOT NULL,
+  internal_rcv_id INTEGER NOT NULL,
+  internal_id INTEGER NOT NULL,
+  external_snd_id INTEGER NOT NULL,
+  broker_id BLOB NOT NULL,
+  broker_ts TEXT NOT NULL,
+  internal_hash BLOB NOT NULL,
+  external_prev_snd_hash BLOB NOT NULL,
+  integrity BLOB NOT NULL,
+  PRIMARY KEY (conn_id, internal_rcv_id),
+  FOREIGN KEY (conn_id, internal_id) REFERENCES messages
+    ON DELETE CASCADE
+) WITHOUT ROWID;
+
+CREATE TABLE snd_messages (
+  conn_id BLOB NOT NULL,
+  internal_snd_id INTEGER NOT NULL,
+  internal_id INTEGER NOT NULL,
+  internal_hash BLOB NOT NULL,
+  previous_msg_hash BLOB NOT NULL DEFAULT x'',
+  PRIMARY KEY (conn_id, internal_snd_id),
+  FOREIGN KEY (conn_id, internal_id) REFERENCES messages
+    ON DELETE CASCADE
+) WITHOUT ROWID;
+
+CREATE TABLE conn_confirmations (
+  confirmation_id BLOB NOT NULL PRIMARY KEY,
+  conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  e2e_snd_pub_key BLOB NOT NULL, -- TODO per-queue key. Split?
+  sender_key BLOB NOT NULL, -- TODO per-queue key. Split?
+  ratchet_state BLOB NOT NULL,
+  sender_conn_info BLOB NOT NULL,
+  accepted INTEGER NOT NULL,
+  own_conn_info BLOB,
+  created_at TEXT NOT NULL DEFAULT (datetime('now'))
+) WITHOUT ROWID;
+
+CREATE TABLE conn_invitations (
+  invitation_id BLOB NOT NULL PRIMARY KEY,
+  contact_conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  cr_invitation BLOB NOT NULL,
+  recipient_conn_info BLOB NOT NULL,
+  accepted INTEGER NOT NULL DEFAULT 0,
+  own_conn_info BLOB,
+  created_at TEXT NOT NULL DEFAULT (datetime('now'))
+) WITHOUT ROWID;
+
+CREATE TABLE ratchets (
+  conn_id BLOB NOT NULL PRIMARY KEY REFERENCES connections
+    ON DELETE CASCADE,
+  -- x3dh keys are not saved on the sending side (the side accepting the connection)
+  x3dh_priv_key_1 BLOB,
+  x3dh_priv_key_2 BLOB,
+  -- ratchet is initially empty on the receiving side (the side offering the connection)
+  ratchet_state BLOB,
+  e2e_version INTEGER NOT NULL DEFAULT 1
+) WITHOUT ROWID;
+
+CREATE TABLE skipped_messages (
+  skipped_message_id INTEGER PRIMARY KEY,
+  conn_id BLOB NOT NULL REFERENCES ratchets
+    ON DELETE CASCADE,
+  header_key BLOB NOT NULL,
+  msg_n INTEGER NOT NULL,
+  msg_key BLOB NOT NULL
+);
+|]

src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20220301_snd_queue_keys.hs

@@ -0,0 +1,13 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220301_snd_queue_keys where
+
+import Database.SQLite.Simple (Query)
+import Database.SQLite.Simple.QQ (sql)
+
+m20220301_snd_queue_keys :: Query
+m20220301_snd_queue_keys =
+  [sql|
+ALTER TABLE snd_queues ADD COLUMN snd_public_key BLOB;
+ALTER TABLE snd_queues ADD COLUMN e2e_pub_key BLOB;
+|]

src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20220322_notifications.hs

@@ -0,0 +1,39 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220322_notifications where
+
+import Database.SQLite.Simple (Query)
+import Database.SQLite.Simple.QQ (sql)
+
+m20220322_notifications :: Query
+m20220322_notifications =
+  [sql|
+CREATE TABLE ntf_servers (
+  ntf_host TEXT NOT NULL,
+  ntf_port TEXT NOT NULL,
+  ntf_key_hash BLOB NOT NULL,
+  created_at TEXT NOT NULL DEFAULT (datetime('now')),
+  updated_at TEXT NOT NULL DEFAULT (datetime('now')),
+  PRIMARY KEY (ntf_host, ntf_port)
+) WITHOUT ROWID;
+
+CREATE TABLE ntf_tokens (
+  provider TEXT NOT NULL, -- apn
+  device_token TEXT NOT NULL, -- ! this field is mislabeled and is actually saved as binary
+  ntf_host TEXT NOT NULL,
+  ntf_port TEXT NOT NULL,
+  tkn_id BLOB, -- token ID assigned by notifications server
+  tkn_pub_key BLOB NOT NULL, -- client's public key to verify token commands (used by server, for repeat registraions)
+  tkn_priv_key BLOB NOT NULL, -- client's private key to sign token commands
+  tkn_pub_dh_key BLOB NOT NULL, -- client's public DH key (for repeat registraions)
+  tkn_priv_dh_key BLOB NOT NULL, -- client's private DH key (for repeat registraions)
+  tkn_dh_secret BLOB, -- DH secret for e2e encryption of notifications
+  tkn_status TEXT NOT NULL,
+  tkn_action BLOB,
+  created_at TEXT NOT NULL DEFAULT (datetime('now')),
+  updated_at TEXT NOT NULL DEFAULT (datetime('now')), -- this is to check token status periodically to know when it was last checked
+  PRIMARY KEY (provider, device_token, ntf_host, ntf_port),
+  FOREIGN KEY (ntf_host, ntf_port) REFERENCES ntf_servers
+    ON DELETE RESTRICT ON UPDATE CASCADE
+) WITHOUT ROWID;
+|]

src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20220404_ntf_subscriptions_draft.hs

@@ -0,0 +1,38 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Messaging.Agent.Store.SQLite.Migrations.M20220404_ntf_subscriptions_draft where
+
+import Database.SQLite.Simple (Query)
+import Database.SQLite.Simple.QQ (sql)
+
+m20220404_ntf_subscriptions_draft :: Query
+m20220404_ntf_subscriptions_draft =
+  [sql|
+ALTER TABLE rcv_queues ADD COLUMN ntf_id BLOB;
+
+ALTER TABLE rcv_queues ADD COLUMN ntf_public_key BLOB;
+
+ALTER TABLE rcv_queues ADD COLUMN ntf_private_key BLOB;
+
+CREATE UNIQUE INDEX idx_rcv_queues_ntf ON rcv_queues (host, port, ntf_id);
+
+CREATE TABLE ntf_subscriptions (
+  ntf_host TEXT NOT NULL,
+  ntf_port TEXT NOT NULL,
+  ntf_sub_id BLOB NOT NULL,
+  ntf_sub_status TEXT NOT NULL, -- new, created, active, pending, error_auth
+  ntf_sub_action TEXT, -- if there is an action required on this subscription: create / check / token / delete
+  ntf_sub_action_ts TEXT, -- the earliest time for the action, e.g. checks can be scheduled every X hours
+  ntf_token TEXT NOT NULL, -- or BLOB?
+  smp_host TEXT NOT NULL,
+  smp_port TEXT NOT NULL,
+  smp_ntf_id BLOB NOT NULL,
+  created_at TEXT NOT NULL,
+  updated_at TEXT NOT NULL, -- this is to check subscription status periodically to know when it was last checked
+  PRIMARY KEY (ntf_host, ntf_port, ntf_sub_id),
+  FOREIGN KEY (ntf_host, ntf_port) REFERENCES ntf_servers
+    ON DELETE RESTRICT ON UPDATE CASCADE,
+  FOREIGN KEY (smp_host, smp_port, smp_ntf_id) REFERENCES rcv_queues (host, port, ntf_id)
+    ON DELETE RESTRICT ON UPDATE CASCADE
+) WITHOUT ROWID;
+|]

src/Simplex/Messaging/Agent/Store/SQLite/Migrations/agent_schema.sql

@@ -0,0 +1,161 @@
+CREATE TABLE migrations(
+  name TEXT NOT NULL,
+  ts TEXT NOT NULL,
+  PRIMARY KEY(name)
+);
+CREATE TABLE servers(
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  key_hash BLOB NOT NULL,
+  PRIMARY KEY(host, port)
+) WITHOUT ROWID;
+CREATE TABLE connections(
+  conn_id BLOB NOT NULL PRIMARY KEY,
+  conn_mode TEXT NOT NULL,
+  last_internal_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_internal_rcv_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_internal_snd_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_external_snd_msg_id INTEGER NOT NULL DEFAULT 0,
+  last_rcv_msg_hash BLOB NOT NULL DEFAULT x'',
+  last_snd_msg_hash BLOB NOT NULL DEFAULT x'',
+  smp_agent_version INTEGER NOT NULL DEFAULT 1
+) WITHOUT ROWID;
+CREATE TABLE rcv_queues(
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  rcv_id BLOB NOT NULL,
+  conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  rcv_private_key BLOB NOT NULL,
+  rcv_dh_secret BLOB NOT NULL,
+  e2e_priv_key BLOB NOT NULL,
+  e2e_dh_secret BLOB,
+  snd_id BLOB NOT NULL,
+  snd_key BLOB,
+  status TEXT NOT NULL,
+  smp_server_version INTEGER NOT NULL DEFAULT 1,
+  smp_client_version INTEGER,
+  PRIMARY KEY(host, port, rcv_id),
+  FOREIGN KEY(host, port) REFERENCES servers
+  ON DELETE RESTRICT ON UPDATE CASCADE,
+  UNIQUE(host, port, snd_id)
+) WITHOUT ROWID;
+CREATE TABLE snd_queues(
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  snd_id BLOB NOT NULL,
+  conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  snd_private_key BLOB NOT NULL,
+  e2e_dh_secret BLOB NOT NULL,
+  status TEXT NOT NULL,
+  smp_server_version INTEGER NOT NULL DEFAULT 1,
+  smp_client_version INTEGER NOT NULL DEFAULT 1,
+  snd_public_key BLOB,
+  e2e_pub_key BLOB,
+  PRIMARY KEY(host, port, snd_id),
+  FOREIGN KEY(host, port) REFERENCES servers
+  ON DELETE RESTRICT ON UPDATE CASCADE
+) WITHOUT ROWID;
+CREATE TABLE messages(
+  conn_id BLOB NOT NULL REFERENCES connections(conn_id)
+  ON DELETE CASCADE,
+  internal_id INTEGER NOT NULL,
+  internal_ts TEXT NOT NULL,
+  internal_rcv_id INTEGER,
+  internal_snd_id INTEGER,
+  msg_type BLOB NOT NULL, --(H)ELLO,(R)EPLY,(D)ELETE. Should SMP confirmation be saved too?
+  msg_body BLOB NOT NULL DEFAULT x'',
+  PRIMARY KEY(conn_id, internal_id),
+  FOREIGN KEY(conn_id, internal_rcv_id) REFERENCES rcv_messages
+  ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED,
+  FOREIGN KEY(conn_id, internal_snd_id) REFERENCES snd_messages
+  ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED
+) WITHOUT ROWID;
+CREATE TABLE rcv_messages(
+  conn_id BLOB NOT NULL,
+  internal_rcv_id INTEGER NOT NULL,
+  internal_id INTEGER NOT NULL,
+  external_snd_id INTEGER NOT NULL,
+  broker_id BLOB NOT NULL,
+  broker_ts TEXT NOT NULL,
+  internal_hash BLOB NOT NULL,
+  external_prev_snd_hash BLOB NOT NULL,
+  integrity BLOB NOT NULL,
+  PRIMARY KEY(conn_id, internal_rcv_id),
+  FOREIGN KEY(conn_id, internal_id) REFERENCES messages
+  ON DELETE CASCADE
+) WITHOUT ROWID;
+CREATE TABLE snd_messages(
+  conn_id BLOB NOT NULL,
+  internal_snd_id INTEGER NOT NULL,
+  internal_id INTEGER NOT NULL,
+  internal_hash BLOB NOT NULL,
+  previous_msg_hash BLOB NOT NULL DEFAULT x'',
+  PRIMARY KEY(conn_id, internal_snd_id),
+  FOREIGN KEY(conn_id, internal_id) REFERENCES messages
+  ON DELETE CASCADE
+) WITHOUT ROWID;
+CREATE TABLE conn_confirmations(
+  confirmation_id BLOB NOT NULL PRIMARY KEY,
+  conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  e2e_snd_pub_key BLOB NOT NULL, -- TODO per-queue key. Split?
+  sender_key BLOB NOT NULL, -- TODO per-queue key. Split?
+  ratchet_state BLOB NOT NULL,
+  sender_conn_info BLOB NOT NULL,
+  accepted INTEGER NOT NULL,
+  own_conn_info BLOB,
+  created_at TEXT NOT NULL DEFAULT(datetime('now'))
+) WITHOUT ROWID;
+CREATE TABLE conn_invitations(
+  invitation_id BLOB NOT NULL PRIMARY KEY,
+  contact_conn_id BLOB NOT NULL REFERENCES connections ON DELETE CASCADE,
+  cr_invitation BLOB NOT NULL,
+  recipient_conn_info BLOB NOT NULL,
+  accepted INTEGER NOT NULL DEFAULT 0,
+  own_conn_info BLOB,
+  created_at TEXT NOT NULL DEFAULT(datetime('now'))
+) WITHOUT ROWID;
+CREATE TABLE ratchets(
+  conn_id BLOB NOT NULL PRIMARY KEY REFERENCES connections
+  ON DELETE CASCADE,
+  -- x3dh keys are not saved on the sending side(the side accepting the connection)
+  x3dh_priv_key_1 BLOB,
+  x3dh_priv_key_2 BLOB,
+  -- ratchet is initially empty on the receiving side(the side offering the connection)
+  ratchet_state BLOB,
+  e2e_version INTEGER NOT NULL DEFAULT 1
+) WITHOUT ROWID;
+CREATE TABLE skipped_messages(
+  skipped_message_id INTEGER PRIMARY KEY,
+  conn_id BLOB NOT NULL REFERENCES ratchets
+  ON DELETE CASCADE,
+  header_key BLOB NOT NULL,
+  msg_n INTEGER NOT NULL,
+  msg_key BLOB NOT NULL
+);
+CREATE TABLE ntf_servers(
+  ntf_host TEXT NOT NULL,
+  ntf_port TEXT NOT NULL,
+  ntf_key_hash BLOB NOT NULL,
+  created_at TEXT NOT NULL DEFAULT(datetime('now')),
+  updated_at TEXT NOT NULL DEFAULT(datetime('now')),
+  PRIMARY KEY(ntf_host, ntf_port)
+) WITHOUT ROWID;
+CREATE TABLE ntf_tokens(
+  provider TEXT NOT NULL, -- apn
+  device_token TEXT NOT NULL, -- ! this field is mislabeled and is actually saved as binary
+  ntf_host TEXT NOT NULL,
+  ntf_port TEXT NOT NULL,
+  tkn_id BLOB, -- token ID assigned by notifications server
+  tkn_pub_key BLOB NOT NULL, -- client's public key to verify token commands(used by server, for repeat registraions)
+tkn_priv_key BLOB NOT NULL, -- client's private key to sign token commands
+tkn_pub_dh_key BLOB NOT NULL, -- client's public DH key(for repeat registraions)
+tkn_priv_dh_key BLOB NOT NULL, -- client's private DH key(for repeat registraions)
+tkn_dh_secret BLOB, -- DH secret for e2e encryption of notifications
+  tkn_status TEXT NOT NULL,
+  tkn_action BLOB,
+  created_at TEXT NOT NULL DEFAULT(datetime('now')),
+  updated_at TEXT NOT NULL DEFAULT(datetime('now')), -- this is to check token status periodically to know when it was last checked
+  PRIMARY KEY(provider, device_token, ntf_host, ntf_port),
+  FOREIGN KEY(ntf_host, ntf_port) REFERENCES ntf_servers
+  ON DELETE RESTRICT ON UPDATE CASCADE
+) WITHOUT ROWID;

src/Simplex/Messaging/Client.hs

@@ -0,0 +1,381 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE NumericUnderscores #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+
+-- |
+-- Module      : Simplex.Messaging.Client
+-- Copyright   : (c) simplex.chat
+-- License     : AGPL-3
+--
+-- Maintainer  : chat@simplex.chat
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- This module provides a functional client API for SMP protocol.
+--
+-- See https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md
+module Simplex.Messaging.Client
+  ( -- * Connect (disconnect) client to (from) SMP server
+    ProtocolClient (sessionId),
+    SMPClient,
+    getProtocolClient,
+    closeProtocolClient,
+
+    -- * SMP protocol command functions
+    createSMPQueue,
+    subscribeSMPQueue,
+    subscribeSMPQueueNotifications,
+    secureSMPQueue,
+    enableSMPQueueNotifications,
+    sendSMPMessage,
+    ackSMPMessage,
+    suspendSMPQueue,
+    deleteSMPQueue,
+    sendProtocolCommand,
+
+    -- * Supporting types and client configuration
+    ProtocolClientError (..),
+    ProtocolClientConfig (..),
+    defaultClientConfig,
+    ServerTransmission,
+  )
+where
+
+import Control.Concurrent (threadDelay)
+import Control.Concurrent.Async
+import Control.Concurrent.STM
+import Control.Exception
+import Control.Monad
+import Control.Monad.Trans.Class
+import Control.Monad.Trans.Except
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Maybe (fromMaybe)
+import Network.Socket (ServiceName)
+import Numeric.Natural
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Protocol as SMP
+import Simplex.Messaging.TMap (TMap)
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Transport
+import Simplex.Messaging.Transport.Client (runTransportClient)
+import Simplex.Messaging.Transport.KeepAlive
+import Simplex.Messaging.Transport.WebSockets (WS)
+import Simplex.Messaging.Util (bshow, liftError, raceAny_)
+import System.Timeout (timeout)
+
+-- | 'SMPClient' is a handle used to send commands to a specific SMP server.
+--
+-- Use 'getSMPClient' to connect to an SMP server and create a client handle.
+data ProtocolClient msg = ProtocolClient
+  { action :: Async (),
+    connected :: TVar Bool,
+    sessionId :: SessionId,
+    protocolServer :: ProtocolServer,
+    tcpTimeout :: Int,
+    clientCorrId :: TVar Natural,
+    sentCommands :: TMap CorrId (Request msg),
+    sndQ :: TBQueue SentRawTransmission,
+    rcvQ :: TBQueue (SignedTransmission msg),
+    msgQ :: Maybe (TBQueue (ServerTransmission msg))
+  }
+
+type SMPClient = ProtocolClient SMP.BrokerMsg
+
+-- | Type synonym for transmission from some SPM server queue.
+type ServerTransmission msg = (ProtocolServer, SessionId, QueueId, msg)
+
+-- | protocol client configuration.
+data ProtocolClientConfig = ProtocolClientConfig
+  { -- | size of TBQueue to use for server commands and responses
+    qSize :: Natural,
+    -- | default server port if port is not specified in ProtocolServer
+    defaultTransport :: (ServiceName, ATransport),
+    -- | timeout of TCP commands (microseconds)
+    tcpTimeout :: Int,
+    -- | TCP keep-alive options, Nothing to skip enabling keep-alive
+    tcpKeepAlive :: Maybe KeepAliveOpts,
+    -- | period for SMP ping commands (microseconds)
+    smpPing :: Int
+  }
+
+-- | Default protocol client configuration.
+defaultClientConfig :: ProtocolClientConfig
+defaultClientConfig =
+  ProtocolClientConfig
+    { qSize = 64,
+      defaultTransport = ("443", transport @TLS),
+      tcpTimeout = 5_000_000,
+      tcpKeepAlive = Just defaultKeepAliveOpts,
+      smpPing = 600_000_000 -- 10min
+    }
+
+data Request msg = Request
+  { queueId :: QueueId,
+    responseVar :: TMVar (Response msg)
+  }
+
+type Response msg = Either ProtocolClientError msg
+
+-- | Connects to 'ProtocolServer' using passed client configuration
+-- and queue for messages and notifications.
+--
+-- A single queue can be used for multiple 'SMPClient' instances,
+-- as 'SMPServerTransmission' includes server information.
+getProtocolClient :: forall msg. Protocol msg => ProtocolServer -> ProtocolClientConfig -> Maybe (TBQueue (ServerTransmission msg)) -> IO () -> IO (Either ProtocolClientError (ProtocolClient msg))
+getProtocolClient protocolServer cfg@ProtocolClientConfig {qSize, tcpTimeout, tcpKeepAlive, smpPing} msgQ disconnected =
+  (atomically mkProtocolClient >>= runClient useTransport)
+    `catch` \(e :: IOException) -> pure . Left $ PCEIOError e
+  where
+    mkProtocolClient :: STM (ProtocolClient msg)
+    mkProtocolClient = do
+      connected <- newTVar False
+      clientCorrId <- newTVar 0
+      sentCommands <- TM.empty
+      sndQ <- newTBQueue qSize
+      rcvQ <- newTBQueue qSize
+      return
+        ProtocolClient
+          { action = undefined,
+            sessionId = undefined,
+            connected,
+            protocolServer,
+            tcpTimeout,
+            clientCorrId,
+            sentCommands,
+            sndQ,
+            rcvQ,
+            msgQ
+          }
+
+    runClient :: (ServiceName, ATransport) -> ProtocolClient msg -> IO (Either ProtocolClientError (ProtocolClient msg))
+    runClient (port', ATransport t) c = do
+      thVar <- newEmptyTMVarIO
+      action <-
+        async $
+          runTransportClient (host protocolServer) port' (Just $ keyHash protocolServer) tcpKeepAlive (client t c thVar)
+            `finally` atomically (putTMVar thVar $ Left PCENetworkError)
+      th_ <- tcpTimeout `timeout` atomically (takeTMVar thVar)
+      pure $ case th_ of
+        Just (Right THandle {sessionId}) -> Right c {action, sessionId}
+        Just (Left e) -> Left e
+        Nothing -> Left PCENetworkError
+
+    useTransport :: (ServiceName, ATransport)
+    useTransport = case port protocolServer of
+      "" -> defaultTransport cfg
+      "80" -> ("80", transport @WS)
+      p -> (p, transport @TLS)
+
+    client :: forall c. Transport c => TProxy c -> ProtocolClient msg -> TMVar (Either ProtocolClientError (THandle c)) -> c -> IO ()
+    client _ c thVar h =
+      runExceptT (protocolClientHandshake @msg h $ keyHash protocolServer) >>= \case
+        Left e -> atomically . putTMVar thVar . Left $ PCETransportError e
+        Right th@THandle {sessionId} -> do
+          atomically $ do
+            writeTVar (connected c) True
+            putTMVar thVar $ Right th
+          let c' = c {sessionId} :: ProtocolClient msg
+          -- TODO remove ping if 0 is passed (or Nothing?)
+          raceAny_ [send c' th, process c', receive c' th, ping c']
+            `finally` disconnected
+
+    send :: Transport c => ProtocolClient msg -> THandle c -> IO ()
+    send ProtocolClient {sndQ} h = forever $ atomically (readTBQueue sndQ) >>= tPut h
+
+    receive :: Transport c => ProtocolClient msg -> THandle c -> IO ()
+    receive ProtocolClient {rcvQ} h = forever $ tGet h >>= atomically . writeTBQueue rcvQ
+
+    ping :: ProtocolClient msg -> IO ()
+    ping c = forever $ do
+      threadDelay smpPing
+      runExceptT $ sendProtocolCommand c Nothing "" protocolPing
+
+    process :: ProtocolClient msg -> IO ()
+    process ProtocolClient {sessionId, rcvQ, sentCommands} = forever $ do
+      (_, _, (corrId, qId, respOrErr)) <- atomically $ readTBQueue rcvQ
+      if B.null $ bs corrId
+        then sendMsg qId respOrErr
+        else do
+          atomically (TM.lookup corrId sentCommands) >>= \case
+            Nothing -> sendMsg qId respOrErr
+            Just Request {queueId, responseVar} -> atomically $ do
+              TM.delete corrId sentCommands
+              putTMVar responseVar $
+                if queueId == qId
+                  then case respOrErr of
+                    Left e -> Left $ PCEResponseError e
+                    Right r -> case protocolError r of
+                      Just e -> Left $ PCEProtocolError e
+                      _ -> Right r
+                  else Left PCEUnexpectedResponse
+      where
+        sendMsg :: QueueId -> Either ErrorType msg -> IO ()
+        sendMsg qId = \case
+          Right cmd -> atomically $ mapM_ (`writeTBQueue` (protocolServer, sessionId, qId, cmd)) msgQ
+          -- TODO send everything else to errQ and log in agent
+          _ -> return ()
+
+-- | Disconnects client from the server and terminates client threads.
+closeProtocolClient :: ProtocolClient msg -> IO ()
+closeProtocolClient = uninterruptibleCancel . action
+
+-- | SMP client error type.
+data ProtocolClientError
+  = -- | Correctly parsed SMP server ERR response.
+    -- This error is forwarded to the agent client as `ERR SMP err`.
+    PCEProtocolError ErrorType
+  | -- | Invalid server response that failed to parse.
+    -- Forwarded to the agent client as `ERR BROKER RESPONSE`.
+    PCEResponseError ErrorType
+  | -- | Different response from what is expected to a certain SMP command,
+    -- e.g. server should respond `IDS` or `ERR` to `NEW` command,
+    -- other responses would result in this error.
+    -- Forwarded to the agent client as `ERR BROKER UNEXPECTED`.
+    PCEUnexpectedResponse
+  | -- | Used for TCP connection and command response timeouts.
+    -- Forwarded to the agent client as `ERR BROKER TIMEOUT`.
+    PCEResponseTimeout
+  | -- | Failure to establish TCP connection.
+    -- Forwarded to the agent client as `ERR BROKER NETWORK`.
+    PCENetworkError
+  | -- | TCP transport handshake or some other transport error.
+    -- Forwarded to the agent client as `ERR BROKER TRANSPORT e`.
+    PCETransportError TransportError
+  | -- | Error when cryptographically "signing" the command.
+    PCESignatureError C.CryptoError
+  | -- | IO Error
+    PCEIOError IOException
+  deriving (Eq, Show, Exception)
+
+-- | Create a new SMP queue.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#create-queue-command
+createSMPQueue ::
+  SMPClient ->
+  RcvPrivateSignKey ->
+  RcvPublicVerifyKey ->
+  RcvPublicDhKey ->
+  ExceptT ProtocolClientError IO QueueIdsKeys
+createSMPQueue c rpKey rKey dhKey =
+  sendSMPCommand c (Just rpKey) "" (NEW rKey dhKey) >>= \case
+    IDS qik -> pure qik
+    _ -> throwE PCEUnexpectedResponse
+
+-- | Subscribe to the SMP queue.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#subscribe-to-queue
+subscribeSMPQueue :: SMPClient -> RcvPrivateSignKey -> RecipientId -> ExceptT ProtocolClientError IO ()
+subscribeSMPQueue c@ProtocolClient {protocolServer, sessionId, msgQ} rpKey rId =
+  sendSMPCommand c (Just rpKey) rId SUB >>= \case
+    OK -> return ()
+    cmd@MSG {} ->
+      lift . atomically $ mapM_ (`writeTBQueue` (protocolServer, sessionId, rId, cmd)) msgQ
+    _ -> throwE PCEUnexpectedResponse
+
+-- | Subscribe to the SMP queue notifications.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#subscribe-to-queue-notifications
+subscribeSMPQueueNotifications :: SMPClient -> NtfPrivateSignKey -> NotifierId -> ExceptT ProtocolClientError IO ()
+subscribeSMPQueueNotifications = okSMPCommand NSUB
+
+-- | Secure the SMP queue by adding a sender public key.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#secure-queue-command
+secureSMPQueue :: SMPClient -> RcvPrivateSignKey -> RecipientId -> SndPublicVerifyKey -> ExceptT ProtocolClientError IO ()
+secureSMPQueue c rpKey rId senderKey = okSMPCommand (KEY senderKey) c rpKey rId
+
+-- | Enable notifications for the queue for push notifications server.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#enable-notifications-command
+enableSMPQueueNotifications :: SMPClient -> RcvPrivateSignKey -> RecipientId -> NtfPublicVerifyKey -> ExceptT ProtocolClientError IO NotifierId
+enableSMPQueueNotifications c rpKey rId notifierKey =
+  sendSMPCommand c (Just rpKey) rId (NKEY notifierKey) >>= \case
+    NID nId -> pure nId
+    _ -> throwE PCEUnexpectedResponse
+
+-- | Send SMP message.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#send-message
+sendSMPMessage :: SMPClient -> Maybe SndPrivateSignKey -> SenderId -> MsgBody -> ExceptT ProtocolClientError IO ()
+sendSMPMessage c spKey sId msg =
+  sendSMPCommand c spKey sId (SEND msg) >>= \case
+    OK -> pure ()
+    _ -> throwE PCEUnexpectedResponse
+
+-- | Acknowledge message delivery (server deletes the message).
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#acknowledge-message-delivery
+ackSMPMessage :: SMPClient -> RcvPrivateSignKey -> QueueId -> ExceptT ProtocolClientError IO ()
+ackSMPMessage c@ProtocolClient {protocolServer, sessionId, msgQ} rpKey rId =
+  sendSMPCommand c (Just rpKey) rId ACK >>= \case
+    OK -> return ()
+    cmd@MSG {} ->
+      lift . atomically $ mapM_ (`writeTBQueue` (protocolServer, sessionId, rId, cmd)) msgQ
+    _ -> throwE PCEUnexpectedResponse
+
+-- | Irreversibly suspend SMP queue.
+-- The existing messages from the queue will still be delivered.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#suspend-queue
+suspendSMPQueue :: SMPClient -> RcvPrivateSignKey -> QueueId -> ExceptT ProtocolClientError IO ()
+suspendSMPQueue = okSMPCommand OFF
+
+-- | Irreversibly delete SMP queue and all messages in it.
+--
+-- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#delete-queue
+deleteSMPQueue :: SMPClient -> RcvPrivateSignKey -> QueueId -> ExceptT ProtocolClientError IO ()
+deleteSMPQueue = okSMPCommand DEL
+
+okSMPCommand :: PartyI p => Command p -> SMPClient -> C.APrivateSignKey -> QueueId -> ExceptT ProtocolClientError IO ()
+okSMPCommand cmd c pKey qId =
+  sendSMPCommand c (Just pKey) qId cmd >>= \case
+    OK -> return ()
+    _ -> throwE PCEUnexpectedResponse
+
+-- | Send SMP command
+sendSMPCommand :: PartyI p => SMPClient -> Maybe C.APrivateSignKey -> QueueId -> Command p -> ExceptT ProtocolClientError IO BrokerMsg
+sendSMPCommand c pKey qId cmd = sendProtocolCommand c pKey qId (Cmd sParty cmd)
+
+-- | Send Protocol command
+sendProtocolCommand :: forall msg. ProtocolEncoding (ProtocolCommand msg) => ProtocolClient msg -> Maybe C.APrivateSignKey -> QueueId -> ProtocolCommand msg -> ExceptT ProtocolClientError IO msg
+sendProtocolCommand ProtocolClient {sndQ, sentCommands, clientCorrId, sessionId, tcpTimeout} pKey qId cmd = do
+  corrId <- lift_ getNextCorrId
+  t <- signTransmission $ encodeTransmission sessionId (corrId, qId, cmd)
+  ExceptT $ sendRecv corrId t
+  where
+    lift_ :: STM a -> ExceptT ProtocolClientError IO a
+    lift_ action = ExceptT $ Right <$> atomically action
+
+    getNextCorrId :: STM CorrId
+    getNextCorrId = do
+      i <- stateTVar clientCorrId $ \i -> (i, i + 1)
+      pure . CorrId $ bshow i
+
+    signTransmission :: ByteString -> ExceptT ProtocolClientError IO SentRawTransmission
+    signTransmission t = case pKey of
+      Nothing -> return (Nothing, t)
+      Just pk -> do
+        sig <- liftError PCESignatureError $ C.sign pk t
+        return (Just sig, t)
+
+    -- two separate "atomically" needed to avoid blocking
+    sendRecv :: CorrId -> SentRawTransmission -> IO (Response msg)
+    sendRecv corrId t = atomically (send corrId t) >>= withTimeout . atomically . takeTMVar
+      where
+        withTimeout a = fromMaybe (Left PCEResponseTimeout) <$> timeout tcpTimeout a
+
+    send :: CorrId -> SentRawTransmission -> STM (TMVar (Response msg))
+    send corrId t = do
+      r <- newEmptyTMVar
+      TM.insert corrId (Request qId r) sentCommands
+      writeTBQueue sndQ t
+      return r

src/Simplex/Messaging/Client/Agent.hs

@@ -0,0 +1,301 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE InstanceSigs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+module Simplex.Messaging.Client.Agent where
+
+import Control.Concurrent (forkIO)
+import Control.Concurrent.Async (Async, uninterruptibleCancel)
+import Control.Logger.Simple
+import Control.Monad.Except
+import Control.Monad.IO.Unlift
+import Control.Monad.Trans.Except
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Set (Set)
+import Data.Text.Encoding
+import Numeric.Natural
+import Simplex.Messaging.Agent.RetryInterval
+import Simplex.Messaging.Client
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Protocol (BrokerMsg, ProtocolServer (..), QueueId, SMPServer)
+import Simplex.Messaging.TMap (TMap)
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Util (catchAll_, tryE, whenM, ($>>=))
+import System.Timeout (timeout)
+import UnliftIO (async, forConcurrently_)
+import UnliftIO.Exception (Exception)
+import qualified UnliftIO.Exception as E
+import UnliftIO.STM
+
+type SMPClientVar = TMVar (Either ProtocolClientError SMPClient)
+
+data SMPClientAgentEvent
+  = CAConnected SMPServer
+  | CADisconnected SMPServer (Set SMPSub)
+  | CAReconnected SMPServer
+  | CAResubscribed SMPServer SMPSub
+  | CASubError SMPServer SMPSub ProtocolClientError
+
+data SMPSubParty = SPRecipient | SPNotifier
+  deriving (Eq, Ord)
+
+type SMPSub = (SMPSubParty, QueueId)
+
+-- type SMPServerSub = (SMPServer, SMPSub)
+
+data SMPClientAgentConfig = SMPClientAgentConfig
+  { smpCfg :: ProtocolClientConfig,
+    reconnectInterval :: RetryInterval,
+    msgQSize :: Natural,
+    agentQSize :: Natural
+  }
+
+defaultSMPClientAgentConfig :: SMPClientAgentConfig
+defaultSMPClientAgentConfig =
+  SMPClientAgentConfig
+    { smpCfg = defaultClientConfig,
+      reconnectInterval =
+        RetryInterval
+          { initialInterval = second,
+            increaseAfter = 10 * second,
+            maxInterval = 10 * second
+          },
+      msgQSize = 64,
+      agentQSize = 64
+    }
+  where
+    second = 1000000
+
+data SMPClientAgent = SMPClientAgent
+  { agentCfg :: SMPClientAgentConfig,
+    msgQ :: TBQueue (ServerTransmission BrokerMsg),
+    agentQ :: TBQueue SMPClientAgentEvent,
+    smpClients :: TMap SMPServer SMPClientVar,
+    srvSubs :: TMap SMPServer (TMap SMPSub C.APrivateSignKey),
+    pendingSrvSubs :: TMap SMPServer (TMap SMPSub C.APrivateSignKey),
+    reconnections :: TVar [Async ()],
+    asyncClients :: TVar [Async ()]
+  }
+
+newtype InternalException e = InternalException {unInternalException :: e}
+  deriving (Eq, Show)
+
+instance Exception e => Exception (InternalException e)
+
+instance (MonadUnliftIO m, Exception e) => MonadUnliftIO (ExceptT e m) where
+  withRunInIO :: ((forall a. ExceptT e m a -> IO a) -> IO b) -> ExceptT e m b
+  withRunInIO exceptToIO =
+    withExceptT unInternalException . ExceptT . E.try $
+      withRunInIO $ \run ->
+        exceptToIO $ run . (either (E.throwIO . InternalException) return <=< runExceptT)
+
+newSMPClientAgent :: SMPClientAgentConfig -> STM SMPClientAgent
+newSMPClientAgent agentCfg@SMPClientAgentConfig {msgQSize, agentQSize} = do
+  msgQ <- newTBQueue msgQSize
+  agentQ <- newTBQueue agentQSize
+  smpClients <- TM.empty
+  srvSubs <- TM.empty
+  pendingSrvSubs <- TM.empty
+  reconnections <- newTVar []
+  asyncClients <- newTVar []
+  pure SMPClientAgent {agentCfg, msgQ, agentQ, smpClients, srvSubs, pendingSrvSubs, reconnections, asyncClients}
+
+getSMPServerClient' :: SMPClientAgent -> SMPServer -> ExceptT ProtocolClientError IO SMPClient
+getSMPServerClient' ca@SMPClientAgent {agentCfg, smpClients, msgQ} srv =
+  atomically getClientVar >>= either newSMPClient waitForSMPClient
+  where
+    getClientVar :: STM (Either SMPClientVar SMPClientVar)
+    getClientVar = maybe (Left <$> newClientVar) (pure . Right) =<< TM.lookup srv smpClients
+
+    newClientVar :: STM SMPClientVar
+    newClientVar = do
+      smpVar <- newEmptyTMVar
+      TM.insert srv smpVar smpClients
+      pure smpVar
+
+    waitForSMPClient :: SMPClientVar -> ExceptT ProtocolClientError IO SMPClient
+    waitForSMPClient smpVar = do
+      let ProtocolClientConfig {tcpTimeout} = smpCfg agentCfg
+      smpClient_ <- liftIO $ tcpTimeout `timeout` atomically (readTMVar smpVar)
+      liftEither $ case smpClient_ of
+        Just (Right smpClient) -> Right smpClient
+        Just (Left e) -> Left e
+        Nothing -> Left PCEResponseTimeout
+
+    newSMPClient :: SMPClientVar -> ExceptT ProtocolClientError IO SMPClient
+    newSMPClient smpVar = tryConnectClient pure tryConnectAsync
+      where
+        tryConnectClient :: (SMPClient -> ExceptT ProtocolClientError IO a) -> ExceptT ProtocolClientError IO () -> ExceptT ProtocolClientError IO a
+        tryConnectClient successAction retryAction =
+          tryE connectClient >>= \r -> case r of
+            Right smp -> do
+              logInfo . decodeUtf8 $ "Agent connected to " <> showServer srv
+              atomically $ putTMVar smpVar r
+              successAction smp
+            Left e -> do
+              if e == PCENetworkError || e == PCEResponseTimeout
+                then retryAction
+                else atomically $ do
+                  putTMVar smpVar (Left e)
+                  TM.delete srv smpClients
+              throwE e
+        tryConnectAsync :: ExceptT ProtocolClientError IO ()
+        tryConnectAsync = do
+          a <- async connectAsync
+          atomically $ modifyTVar' (asyncClients ca) (a :)
+        connectAsync :: ExceptT ProtocolClientError IO ()
+        connectAsync =
+          withRetryInterval (reconnectInterval agentCfg) $ \loop ->
+            void $ tryConnectClient (const reconnectClient) loop
+
+    connectClient :: ExceptT ProtocolClientError IO SMPClient
+    connectClient = ExceptT $ getProtocolClient srv (smpCfg agentCfg) (Just msgQ) clientDisconnected
+
+    clientDisconnected :: IO ()
+    clientDisconnected = do
+      removeClientAndSubs >>= (`forM_` serverDown)
+      logInfo . decodeUtf8 $ "Agent disconnected from " <> showServer srv
+
+    removeClientAndSubs :: IO (Maybe (Map SMPSub C.APrivateSignKey))
+    removeClientAndSubs = atomically $ do
+      TM.delete srv smpClients
+      TM.lookupDelete srv (srvSubs ca) >>= mapM updateSubs
+      where
+        updateSubs sVar = do
+          ss <- readTVar sVar
+          addPendingSubs sVar ss
+          pure ss
+
+        addPendingSubs sVar ss = do
+          let ps = pendingSrvSubs ca
+          TM.lookup srv ps >>= \case
+            Just v -> TM.union ss v
+            _ -> TM.insert srv sVar ps
+
+    serverDown :: Map SMPSub C.APrivateSignKey -> IO ()
+    serverDown ss = unless (M.null ss) . void . runExceptT $ do
+      notify . CADisconnected srv $ M.keysSet ss
+      reconnectServer
+
+    reconnectServer :: ExceptT ProtocolClientError IO ()
+    reconnectServer = do
+      a <- async tryReconnectClient
+      atomically $ modifyTVar' (reconnections ca) (a :)
+
+    tryReconnectClient :: ExceptT ProtocolClientError IO ()
+    tryReconnectClient = do
+      withRetryInterval (reconnectInterval agentCfg) $ \loop ->
+        reconnectClient `catchE` const loop
+
+    reconnectClient :: ExceptT ProtocolClientError IO ()
+    reconnectClient = do
+      withSMP ca srv $ \smp -> do
+        notify $ CAReconnected srv
+        cs <- atomically $ mapM readTVar =<< TM.lookup srv (pendingSrvSubs ca)
+        forConcurrently_ (maybe [] M.assocs cs) $ \sub@(s, _) ->
+          whenM (atomically $ hasSub (srvSubs ca) srv s) $
+            subscribe_ smp sub `catchE` handleError s
+      where
+        subscribe_ :: SMPClient -> (SMPSub, C.APrivateSignKey) -> ExceptT ProtocolClientError IO ()
+        subscribe_ smp sub@(s, _) = do
+          smpSubscribe smp sub
+          atomically $ addSubscription ca srv sub
+          notify $ CAResubscribed srv s
+
+        handleError :: SMPSub -> ProtocolClientError -> ExceptT ProtocolClientError IO ()
+        handleError s = \case
+          e@PCEResponseTimeout -> throwE e
+          e@PCENetworkError -> throwE e
+          e -> do
+            notify $ CASubError srv s e
+            atomically $ removePendingSubscription ca srv s
+
+    notify :: SMPClientAgentEvent -> ExceptT ProtocolClientError IO ()
+    notify evt = atomically $ writeTBQueue (agentQ ca) evt
+
+closeSMPClientAgent :: MonadUnliftIO m => SMPClientAgent -> m ()
+closeSMPClientAgent c = liftIO $ do
+  closeSMPServerClients c
+  cancelActions $ reconnections c
+  cancelActions $ asyncClients c
+
+closeSMPServerClients :: SMPClientAgent -> IO ()
+closeSMPServerClients c = readTVarIO (smpClients c) >>= mapM_ (forkIO . closeClient)
+  where
+    closeClient smpVar =
+      atomically (readTMVar smpVar) >>= \case
+        Right smp -> closeProtocolClient smp `catchAll_` pure ()
+        _ -> pure ()
+
+cancelActions :: Foldable f => TVar (f (Async ())) -> IO ()
+cancelActions as = readTVarIO as >>= mapM_ uninterruptibleCancel
+
+withSMP :: SMPClientAgent -> SMPServer -> (SMPClient -> ExceptT ProtocolClientError IO a) -> ExceptT ProtocolClientError IO a
+withSMP ca srv action = (getSMPServerClient' ca srv >>= action) `catchE` logSMPError
+  where
+    logSMPError :: ProtocolClientError -> ExceptT ProtocolClientError IO a
+    logSMPError e = do
+      liftIO $ putStrLn $ "SMP error (" <> show srv <> "): " <> show e
+      throwE e
+
+subscribeQueue :: SMPClientAgent -> SMPServer -> (SMPSub, C.APrivateSignKey) -> ExceptT ProtocolClientError IO ()
+subscribeQueue ca srv sub = do
+  atomically $ addPendingSubscription ca srv sub
+  withSMP ca srv $ \smp -> subscribe_ smp `catchE` handleError
+  where
+    subscribe_ smp = do
+      smpSubscribe smp sub
+      atomically $ addSubscription ca srv sub
+
+    handleError e = do
+      atomically . when (e /= PCENetworkError && e /= PCEResponseTimeout) $
+        removePendingSubscription ca srv $ fst sub
+      throwE e
+
+showServer :: SMPServer -> ByteString
+showServer ProtocolServer {host, port} =
+  B.pack $ host <> if null port then "" else ':' : port
+
+smpSubscribe :: SMPClient -> (SMPSub, C.APrivateSignKey) -> ExceptT ProtocolClientError IO ()
+smpSubscribe smp ((party, queueId), privKey) = subscribe_ smp privKey queueId
+  where
+    subscribe_ = case party of
+      SPRecipient -> subscribeSMPQueue
+      SPNotifier -> subscribeSMPQueueNotifications
+
+addSubscription :: SMPClientAgent -> SMPServer -> (SMPSub, C.APrivateSignKey) -> STM ()
+addSubscription ca srv sub = do
+  addSub_ (srvSubs ca) srv sub
+  removePendingSubscription ca srv $ fst sub
+
+addPendingSubscription :: SMPClientAgent -> SMPServer -> (SMPSub, C.APrivateSignKey) -> STM ()
+addPendingSubscription = addSub_ . pendingSrvSubs
+
+addSub_ :: TMap SMPServer (TMap SMPSub C.APrivateSignKey) -> SMPServer -> (SMPSub, C.APrivateSignKey) -> STM ()
+addSub_ subs srv (s, key) =
+  TM.lookup srv subs >>= \case
+    Just m -> TM.insert s key m
+    _ -> TM.singleton s key >>= \v -> TM.insert srv v subs
+
+removeSubscription :: SMPClientAgent -> SMPServer -> SMPSub -> STM ()
+removeSubscription = removeSub_ . srvSubs
+
+removePendingSubscription :: SMPClientAgent -> SMPServer -> SMPSub -> STM ()
+removePendingSubscription = removeSub_ . pendingSrvSubs
+
+removeSub_ :: TMap SMPServer (TMap SMPSub C.APrivateSignKey) -> SMPServer -> SMPSub -> STM ()
+removeSub_ subs srv s = TM.lookup srv subs >>= mapM_ (TM.delete s)
+
+getSubKey :: TMap SMPServer (TMap SMPSub C.APrivateSignKey) -> SMPServer -> SMPSub -> STM (Maybe C.APrivateSignKey)
+getSubKey subs srv s = TM.lookup srv subs $>>= TM.lookup s
+
+hasSub :: TMap SMPServer (TMap SMPSub C.APrivateSignKey) -> SMPServer -> SMPSub -> STM Bool
+hasSub subs srv s = maybe (pure False) (TM.member s) =<< TM.lookup srv subs

src/Simplex/Messaging/Crypto.hs

@@ -0,0 +1,964 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
+{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}
+
+-- |
+-- Module      : Simplex.Messaging.Crypto
+-- Copyright   : (c) simplex.chat
+-- License     : AGPL-3
+--
+-- Maintainer  : chat@simplex.chat
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- This module provides cryptography implementation for SMP protocols based on
+-- <https://hackage.haskell.org/package/cryptonite cryptonite package>.
+module Simplex.Messaging.Crypto
+  ( -- * Cryptographic keys
+    Algorithm (..),
+    SAlgorithm (..),
+    Alg (..),
+    SignAlg (..),
+    DhAlg (..),
+    DhAlgorithm,
+    PrivateKey (..),
+    PublicKey (..),
+    PrivateKeyX25519,
+    PublicKeyX25519,
+    PrivateKeyX448,
+    PublicKeyX448,
+    APrivateKey (..),
+    APublicKey (..),
+    APrivateSignKey (..),
+    APublicVerifyKey (..),
+    APrivateDhKey (..),
+    APublicDhKey (..),
+    CryptoPublicKey (..),
+    CryptoPrivateKey (..),
+    KeyPair,
+    ASignatureKeyPair,
+    DhSecret (..),
+    DhSecretX25519,
+    ADhSecret (..),
+    KeyHash (..),
+    generateKeyPair,
+    generateKeyPair',
+    generateSignatureKeyPair,
+    generateDhKeyPair,
+    privateToX509,
+    publicKey,
+
+    -- * key encoding/decoding
+    encodePubKey,
+    encodePrivKey,
+    pubKeyBytes,
+
+    -- * sign/verify
+    Signature (..),
+    ASignature (..),
+    CryptoSignature (..),
+    SignatureSize (..),
+    SignatureAlgorithm,
+    AlgorithmI (..),
+    sign,
+    verify,
+    verify',
+    validSignatureSize,
+
+    -- * DH derivation
+    dh',
+    dhBytes',
+
+    -- * AES256 AEAD-GCM scheme
+    Key (..),
+    IV (..),
+    AuthTag (..),
+    encryptAES,
+    decryptAES,
+    encryptAEAD,
+    decryptAEAD,
+    authTagSize,
+    randomAesKey,
+    randomIV,
+    ivSize,
+
+    -- * NaCl crypto_box
+    CbNonce (unCbNonce),
+    cbEncrypt,
+    cbDecrypt,
+    cbNonce,
+    randomCbNonce,
+    pseudoRandomCbNonce,
+
+    -- * pseudo-random bytes
+    pseudoRandomBytes,
+
+    -- * SHA256 hash
+    sha256Hash,
+
+    -- * Message padding / un-padding
+    pad,
+    unPad,
+
+    -- * Cryptography error type
+    CryptoError (..),
+  )
+where
+
+import Control.Concurrent.STM
+import Control.Exception (Exception)
+import Control.Monad.Except
+import Control.Monad.Trans.Except
+import Crypto.Cipher.AES (AES256)
+import qualified Crypto.Cipher.Types as AES
+import qualified Crypto.Cipher.XSalsa as XSalsa
+import qualified Crypto.Error as CE
+import Crypto.Hash (Digest, SHA256 (..), hash)
+import qualified Crypto.MAC.Poly1305 as Poly1305
+import qualified Crypto.PubKey.Curve25519 as X25519
+import qualified Crypto.PubKey.Curve448 as X448
+import qualified Crypto.PubKey.Ed25519 as Ed25519
+import qualified Crypto.PubKey.Ed448 as Ed448
+import Crypto.Random (ChaChaDRG, getRandomBytes, randomBytesGenerate)
+import Data.ASN1.BinaryEncoding
+import Data.ASN1.Encoding
+import Data.ASN1.Types
+import Data.Aeson (FromJSON (..), ToJSON (..))
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.Bifunctor (bimap, first)
+import qualified Data.ByteArray as BA
+import Data.ByteString.Base64 (decode, encode)
+import qualified Data.ByteString.Base64.URL as U
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.ByteString.Internal (c2w, w2c)
+import Data.ByteString.Lazy (fromStrict, toStrict)
+import Data.Constraint (Dict (..))
+import Data.Kind (Constraint, Type)
+import Data.String
+import Data.Type.Equality
+import Data.Typeable (Typeable)
+import Data.X509
+import Database.SQLite.Simple.FromField (FromField (..))
+import Database.SQLite.Simple.ToField (ToField (..))
+import GHC.TypeLits (ErrorMessage (..), TypeError)
+import Network.Transport.Internal (decodeWord16, encodeWord16)
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Parsers (blobFieldDecoder, parseAll, parseString)
+import Simplex.Messaging.Util ((<$?>))
+
+-- | Cryptographic algorithms.
+data Algorithm = Ed25519 | Ed448 | X25519 | X448
+
+-- | Singleton types for 'Algorithm'.
+data SAlgorithm :: Algorithm -> Type where
+  SEd25519 :: SAlgorithm Ed25519
+  SEd448 :: SAlgorithm Ed448
+  SX25519 :: SAlgorithm X25519
+  SX448 :: SAlgorithm X448
+
+deriving instance Eq (SAlgorithm a)
+
+deriving instance Show (SAlgorithm a)
+
+data Alg = forall a. AlgorithmI a => Alg (SAlgorithm a)
+
+data SignAlg
+  = forall a.
+    (AlgorithmI a, SignatureAlgorithm a) =>
+    SignAlg (SAlgorithm a)
+
+data DhAlg
+  = forall a.
+    (AlgorithmI a, DhAlgorithm a) =>
+    DhAlg (SAlgorithm a)
+
+class AlgorithmI (a :: Algorithm) where sAlgorithm :: SAlgorithm a
+
+instance AlgorithmI Ed25519 where sAlgorithm = SEd25519
+
+instance AlgorithmI Ed448 where sAlgorithm = SEd448
+
+instance AlgorithmI X25519 where sAlgorithm = SX25519
+
+instance AlgorithmI X448 where sAlgorithm = SX448
+
+checkAlgorithm :: forall t a a'. (AlgorithmI a, AlgorithmI a') => t a' -> Either String (t a)
+checkAlgorithm x = case testEquality (sAlgorithm @a) (sAlgorithm @a') of
+  Just Refl -> Right x
+  Nothing -> Left "bad algorithm"
+
+instance TestEquality SAlgorithm where
+  testEquality SEd25519 SEd25519 = Just Refl
+  testEquality SEd448 SEd448 = Just Refl
+  testEquality SX25519 SX25519 = Just Refl
+  testEquality SX448 SX448 = Just Refl
+  testEquality _ _ = Nothing
+
+-- | GADT for public keys.
+data PublicKey (a :: Algorithm) where
+  PublicKeyEd25519 :: Ed25519.PublicKey -> PublicKey Ed25519
+  PublicKeyEd448 :: Ed448.PublicKey -> PublicKey Ed448
+  PublicKeyX25519 :: X25519.PublicKey -> PublicKey X25519
+  PublicKeyX448 :: X448.PublicKey -> PublicKey X448
+
+deriving instance Eq (PublicKey a)
+
+deriving instance Show (PublicKey a)
+
+data APublicKey
+  = forall a.
+    AlgorithmI a =>
+    APublicKey (SAlgorithm a) (PublicKey a)
+
+instance Eq APublicKey where
+  APublicKey a k == APublicKey a' k' = case testEquality a a' of
+    Just Refl -> k == k'
+    Nothing -> False
+
+deriving instance Show APublicKey
+
+type PublicKeyX25519 = PublicKey X25519
+
+type PublicKeyX448 = PublicKey X448
+
+-- | GADT for private keys.
+data PrivateKey (a :: Algorithm) where
+  PrivateKeyEd25519 :: Ed25519.SecretKey -> Ed25519.PublicKey -> PrivateKey Ed25519
+  PrivateKeyEd448 :: Ed448.SecretKey -> Ed448.PublicKey -> PrivateKey Ed448
+  PrivateKeyX25519 :: X25519.SecretKey -> X25519.PublicKey -> PrivateKey X25519
+  PrivateKeyX448 :: X448.SecretKey -> X448.PublicKey -> PrivateKey X448
+
+deriving instance Eq (PrivateKey a)
+
+deriving instance Show (PrivateKey a)
+
+data APrivateKey
+  = forall a.
+    AlgorithmI a =>
+    APrivateKey (SAlgorithm a) (PrivateKey a)
+
+instance Eq APrivateKey where
+  APrivateKey a k == APrivateKey a' k' = case testEquality a a' of
+    Just Refl -> k == k'
+    Nothing -> False
+
+deriving instance Show APrivateKey
+
+type PrivateKeyX25519 = PrivateKey X25519
+
+type PrivateKeyX448 = PrivateKey X448
+
+type family SignatureAlgorithm (a :: Algorithm) :: Constraint where
+  SignatureAlgorithm Ed25519 = ()
+  SignatureAlgorithm Ed448 = ()
+  SignatureAlgorithm a =
+    (Int ~ Bool, TypeError (Text "Algorithm " :<>: ShowType a :<>: Text " cannot be used to sign/verify"))
+
+signatureAlgorithm :: SAlgorithm a -> Maybe (Dict (SignatureAlgorithm a))
+signatureAlgorithm = \case
+  SEd25519 -> Just Dict
+  SEd448 -> Just Dict
+  _ -> Nothing
+
+data APrivateSignKey
+  = forall a.
+    (AlgorithmI a, SignatureAlgorithm a) =>
+    APrivateSignKey (SAlgorithm a) (PrivateKey a)
+
+instance Eq APrivateSignKey where
+  APrivateSignKey a k == APrivateSignKey a' k' = case testEquality a a' of
+    Just Refl -> k == k'
+    Nothing -> False
+
+deriving instance Show APrivateSignKey
+
+instance Encoding APrivateSignKey where
+  smpEncode = smpEncode . encodePrivKey
+  {-# INLINE smpEncode #-}
+  smpDecode = decodePrivKey
+  {-# INLINE smpDecode #-}
+
+data APublicVerifyKey
+  = forall a.
+    (AlgorithmI a, SignatureAlgorithm a) =>
+    APublicVerifyKey (SAlgorithm a) (PublicKey a)
+
+instance Eq APublicVerifyKey where
+  APublicVerifyKey a k == APublicVerifyKey a' k' = case testEquality a a' of
+    Just Refl -> k == k'
+    Nothing -> False
+
+deriving instance Show APublicVerifyKey
+
+data APrivateDhKey
+  = forall a.
+    (AlgorithmI a, DhAlgorithm a) =>
+    APrivateDhKey (SAlgorithm a) (PrivateKey a)
+
+instance Eq APrivateDhKey where
+  APrivateDhKey a k == APrivateDhKey a' k' = case testEquality a a' of
+    Just Refl -> k == k'
+    Nothing -> False
+
+deriving instance Show APrivateDhKey
+
+data APublicDhKey
+  = forall a.
+    (AlgorithmI a, DhAlgorithm a) =>
+    APublicDhKey (SAlgorithm a) (PublicKey a)
+
+instance Eq APublicDhKey where
+  APublicDhKey a k == APublicDhKey a' k' = case testEquality a a' of
+    Just Refl -> k == k'
+    Nothing -> False
+
+deriving instance Show APublicDhKey
+
+data DhSecret (a :: Algorithm) where
+  DhSecretX25519 :: X25519.DhSecret -> DhSecret X25519
+  DhSecretX448 :: X448.DhSecret -> DhSecret X448
+
+deriving instance Eq (DhSecret a)
+
+deriving instance Show (DhSecret a)
+
+data ADhSecret
+  = forall a.
+    (AlgorithmI a, DhAlgorithm a) =>
+    ADhSecret (SAlgorithm a) (DhSecret a)
+
+type DhSecretX25519 = DhSecret X25519
+
+type family DhAlgorithm (a :: Algorithm) :: Constraint where
+  DhAlgorithm X25519 = ()
+  DhAlgorithm X448 = ()
+  DhAlgorithm a =
+    (Int ~ Bool, TypeError (Text "Algorithm " :<>: ShowType a :<>: Text " cannot be used for DH exchange"))
+
+dhAlgorithm :: SAlgorithm a -> Maybe (Dict (DhAlgorithm a))
+dhAlgorithm = \case
+  SX25519 -> Just Dict
+  SX448 -> Just Dict
+  _ -> Nothing
+
+dhBytes' :: DhSecret a -> ByteString
+dhBytes' = \case
+  DhSecretX25519 s -> BA.convert s
+  DhSecretX448 s -> BA.convert s
+
+instance AlgorithmI a => StrEncoding (DhSecret a) where
+  strEncode = strEncode . dhBytes'
+  strDecode = (\(ADhSecret _ s) -> checkAlgorithm s) <=< strDecode
+
+instance StrEncoding ADhSecret where
+  strEncode (ADhSecret _ s) = strEncode $ dhBytes' s
+  strDecode = cryptoPassed . secret
+    where
+      secret bs
+        | B.length bs == x25519_size = ADhSecret SX25519 . DhSecretX25519 <$> X25519.dhSecret bs
+        | B.length bs == x448_size = ADhSecret SX448 . DhSecretX448 <$> X448.dhSecret bs
+        | otherwise = CE.CryptoFailed CE.CryptoError_SharedSecretSizeInvalid
+      cryptoPassed = \case
+        CE.CryptoPassed s -> Right s
+        CE.CryptoFailed e -> Left $ show e
+
+instance AlgorithmI a => IsString (DhSecret a) where
+  fromString = parseString strDecode
+
+-- | Class for public key types
+class CryptoPublicKey k where
+  toPubKey :: (forall a. AlgorithmI a => PublicKey a -> b) -> k -> b
+  pubKey :: APublicKey -> Either String k
+
+instance CryptoPublicKey APublicKey where
+  toPubKey f (APublicKey _ k) = f k
+  pubKey = Right
+
+instance CryptoPublicKey APublicVerifyKey where
+  toPubKey f (APublicVerifyKey _ k) = f k
+  pubKey (APublicKey a k) = case signatureAlgorithm a of
+    Just Dict -> Right $ APublicVerifyKey a k
+    _ -> Left "key does not support signature algorithms"
+
+instance CryptoPublicKey APublicDhKey where
+  toPubKey f (APublicDhKey _ k) = f k
+  pubKey (APublicKey a k) = case dhAlgorithm a of
+    Just Dict -> Right $ APublicDhKey a k
+    _ -> Left "key does not support DH algorithms"
+
+instance AlgorithmI a => CryptoPublicKey (PublicKey a) where
+  toPubKey = id
+  pubKey (APublicKey _ k) = checkAlgorithm k
+
+instance Encoding APublicVerifyKey where
+  smpEncode = smpEncode . encodePubKey
+  {-# INLINE smpEncode #-}
+  smpDecode = decodePubKey
+  {-# INLINE smpDecode #-}
+
+instance Encoding APublicDhKey where
+  smpEncode = smpEncode . encodePubKey
+  {-# INLINE smpEncode #-}
+  smpDecode = decodePubKey
+  {-# INLINE smpDecode #-}
+
+instance AlgorithmI a => Encoding (PublicKey a) where
+  smpEncode = smpEncode . encodePubKey
+  {-# INLINE smpEncode #-}
+  smpDecode = decodePubKey
+  {-# INLINE smpDecode #-}
+
+instance StrEncoding APublicVerifyKey where
+  strEncode = strEncode . encodePubKey
+  {-# INLINE strEncode #-}
+  strDecode = decodePubKey
+  {-# INLINE strDecode #-}
+
+instance StrEncoding APublicDhKey where
+  strEncode = strEncode . encodePubKey
+  {-# INLINE strEncode #-}
+  strDecode = decodePubKey
+  {-# INLINE strDecode #-}
+
+instance AlgorithmI a => StrEncoding (PublicKey a) where
+  strEncode = strEncode . encodePubKey
+  {-# INLINE strEncode #-}
+  strDecode = decodePubKey
+  {-# INLINE strDecode #-}
+
+instance AlgorithmI a => ToJSON (PublicKey a) where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+instance AlgorithmI a => FromJSON (PublicKey a) where
+  parseJSON = strParseJSON "PublicKey"
+
+encodePubKey :: CryptoPublicKey k => k -> ByteString
+encodePubKey = toPubKey $ encodeASNObj . publicToX509
+{-# INLINE encodePubKey #-}
+
+pubKeyBytes :: PublicKey a -> ByteString
+pubKeyBytes = \case
+  PublicKeyEd25519 k -> BA.convert k
+  PublicKeyEd448 k -> BA.convert k
+  PublicKeyX25519 k -> BA.convert k
+  PublicKeyX448 k -> BA.convert k
+
+class CryptoPrivateKey pk where
+  type PublicKeyType pk
+  toPrivKey :: (forall a. AlgorithmI a => PrivateKey a -> b) -> pk -> b
+  privKey :: APrivateKey -> Either String pk
+
+instance CryptoPrivateKey APrivateKey where
+  type PublicKeyType APrivateKey = APublicKey
+  toPrivKey f (APrivateKey _ k) = f k
+  privKey = Right
+
+instance CryptoPrivateKey APrivateSignKey where
+  type PublicKeyType APrivateSignKey = APublicVerifyKey
+  toPrivKey f (APrivateSignKey _ k) = f k
+  privKey (APrivateKey a k) = case signatureAlgorithm a of
+    Just Dict -> Right $ APrivateSignKey a k
+    _ -> Left "key does not support signature algorithms"
+
+instance CryptoPrivateKey APrivateDhKey where
+  type PublicKeyType APrivateDhKey = APublicDhKey
+  toPrivKey f (APrivateDhKey _ k) = f k
+  privKey (APrivateKey a k) = case dhAlgorithm a of
+    Just Dict -> Right $ APrivateDhKey a k
+    _ -> Left "key does not support DH algorithm"
+
+instance AlgorithmI a => CryptoPrivateKey (PrivateKey a) where
+  type PublicKeyType (PrivateKey a) = PublicKey a
+  toPrivKey = id
+  privKey (APrivateKey _ k) = checkAlgorithm k
+
+publicKey :: PrivateKey a -> PublicKey a
+publicKey = \case
+  PrivateKeyEd25519 _ k -> PublicKeyEd25519 k
+  PrivateKeyEd448 _ k -> PublicKeyEd448 k
+  PrivateKeyX25519 _ k -> PublicKeyX25519 k
+  PrivateKeyX448 _ k -> PublicKeyX448 k
+
+encodePrivKey :: CryptoPrivateKey pk => pk -> ByteString
+encodePrivKey = toPrivKey $ encodeASNObj . privateToX509
+
+instance AlgorithmI a => IsString (PrivateKey a) where
+  fromString = parseString $ decode >=> decodePrivKey
+
+instance AlgorithmI a => IsString (PublicKey a) where
+  fromString = parseString $ decode >=> decodePubKey
+
+instance AlgorithmI a => ToJSON (PrivateKey a) where
+  toJSON = strToJSON . strEncode . encodePrivKey
+  toEncoding = strToJEncoding . strEncode . encodePrivKey
+
+instance AlgorithmI a => FromJSON (PrivateKey a) where
+  parseJSON v = (decodePrivKey <=< U.decode) <$?> strParseJSON "PrivateKey" v
+
+type KeyPairType pk = (PublicKeyType pk, pk)
+
+type KeyPair a = KeyPairType (PrivateKey a)
+
+type AKeyPair = KeyPairType APrivateKey
+
+type ASignatureKeyPair = KeyPairType APrivateSignKey
+
+type ADhKeyPair = KeyPairType APrivateDhKey
+
+generateKeyPair :: AlgorithmI a => SAlgorithm a -> IO AKeyPair
+generateKeyPair a = bimap (APublicKey a) (APrivateKey a) <$> generateKeyPair'
+
+generateSignatureKeyPair :: (AlgorithmI a, SignatureAlgorithm a) => SAlgorithm a -> IO ASignatureKeyPair
+generateSignatureKeyPair a = bimap (APublicVerifyKey a) (APrivateSignKey a) <$> generateKeyPair'
+
+generateDhKeyPair :: (AlgorithmI a, DhAlgorithm a) => SAlgorithm a -> IO ADhKeyPair
+generateDhKeyPair a = bimap (APublicDhKey a) (APrivateDhKey a) <$> generateKeyPair'
+
+generateKeyPair' :: forall a. AlgorithmI a => IO (KeyPair a)
+generateKeyPair' = case sAlgorithm @a of
+  SEd25519 ->
+    Ed25519.generateSecretKey >>= \pk ->
+      let k = Ed25519.toPublic pk
+       in pure (PublicKeyEd25519 k, PrivateKeyEd25519 pk k)
+  SEd448 ->
+    Ed448.generateSecretKey >>= \pk ->
+      let k = Ed448.toPublic pk
+       in pure (PublicKeyEd448 k, PrivateKeyEd448 pk k)
+  SX25519 ->
+    X25519.generateSecretKey >>= \pk ->
+      let k = X25519.toPublic pk
+       in pure (PublicKeyX25519 k, PrivateKeyX25519 pk k)
+  SX448 ->
+    X448.generateSecretKey >>= \pk ->
+      let k = X448.toPublic pk
+       in pure (PublicKeyX448 k, PrivateKeyX448 pk k)
+
+instance ToField APrivateSignKey where toField = toField . encodePrivKey
+
+instance ToField APublicVerifyKey where toField = toField . encodePubKey
+
+instance ToField APrivateDhKey where toField = toField . encodePrivKey
+
+instance ToField APublicDhKey where toField = toField . encodePubKey
+
+instance AlgorithmI a => ToField (PrivateKey a) where toField = toField . encodePrivKey
+
+instance AlgorithmI a => ToField (PublicKey a) where toField = toField . encodePubKey
+
+instance ToField (DhSecret a) where toField = toField . dhBytes'
+
+instance FromField APrivateSignKey where fromField = blobFieldDecoder decodePrivKey
+
+instance FromField APublicVerifyKey where fromField = blobFieldDecoder decodePubKey
+
+instance FromField APrivateDhKey where fromField = blobFieldDecoder decodePrivKey
+
+instance FromField APublicDhKey where fromField = blobFieldDecoder decodePubKey
+
+instance (Typeable a, AlgorithmI a) => FromField (PrivateKey a) where fromField = blobFieldDecoder decodePrivKey
+
+instance (Typeable a, AlgorithmI a) => FromField (PublicKey a) where fromField = blobFieldDecoder decodePubKey
+
+instance (Typeable a, AlgorithmI a) => FromField (DhSecret a) where fromField = blobFieldDecoder strDecode
+
+instance IsString (Maybe ASignature) where
+  fromString = parseString $ decode >=> decodeSignature
+
+data Signature (a :: Algorithm) where
+  SignatureEd25519 :: Ed25519.Signature -> Signature Ed25519
+  SignatureEd448 :: Ed448.Signature -> Signature Ed448
+
+deriving instance Eq (Signature a)
+
+deriving instance Show (Signature a)
+
+data ASignature
+  = forall a.
+    (AlgorithmI a, SignatureAlgorithm a) =>
+    ASignature (SAlgorithm a) (Signature a)
+
+instance Eq ASignature where
+  ASignature a s == ASignature a' s' = case testEquality a a' of
+    Just Refl -> s == s'
+    _ -> False
+
+deriving instance Show ASignature
+
+class CryptoSignature s where
+  serializeSignature :: s -> ByteString
+  serializeSignature = encode . signatureBytes
+  signatureBytes :: s -> ByteString
+  decodeSignature :: ByteString -> Either String s
+
+instance CryptoSignature ASignature where
+  signatureBytes (ASignature _ sig) = signatureBytes sig
+  decodeSignature s
+    | B.length s == Ed25519.signatureSize =
+      ASignature SEd25519 . SignatureEd25519 <$> ed Ed25519.signature s
+    | B.length s == Ed448.signatureSize =
+      ASignature SEd448 . SignatureEd448 <$> ed Ed448.signature s
+    | otherwise = Left "bad signature size"
+    where
+      ed alg = first show . CE.eitherCryptoError . alg
+
+instance CryptoSignature (Maybe ASignature) where
+  signatureBytes = maybe "" signatureBytes
+  decodeSignature s
+    | B.null s = Right Nothing
+    | otherwise = Just <$> decodeSignature s
+
+instance AlgorithmI a => CryptoSignature (Signature a) where
+  signatureBytes = \case
+    SignatureEd25519 s -> BA.convert s
+    SignatureEd448 s -> BA.convert s
+  decodeSignature s = do
+    ASignature _ sig <- decodeSignature s
+    checkAlgorithm sig
+
+class SignatureSize s where signatureSize :: s -> Int
+
+instance SignatureSize (Signature a) where
+  signatureSize = \case
+    SignatureEd25519 _ -> Ed25519.signatureSize
+    SignatureEd448 _ -> Ed448.signatureSize
+
+instance SignatureSize APrivateSignKey where
+  signatureSize (APrivateSignKey _ k) = signatureSize k
+
+instance SignatureSize APublicVerifyKey where
+  signatureSize (APublicVerifyKey _ k) = signatureSize k
+
+instance SignatureAlgorithm a => SignatureSize (PrivateKey a) where
+  signatureSize = \case
+    PrivateKeyEd25519 _ _ -> Ed25519.signatureSize
+    PrivateKeyEd448 _ _ -> Ed448.signatureSize
+
+instance SignatureAlgorithm a => SignatureSize (PublicKey a) where
+  signatureSize = \case
+    PublicKeyEd25519 _ -> Ed25519.signatureSize
+    PublicKeyEd448 _ -> Ed448.signatureSize
+
+-- | Various cryptographic or related errors.
+data CryptoError
+  = -- | AES initialization error
+    AESCipherError CE.CryptoError
+  | -- | IV generation error
+    CryptoIVError
+  | -- | AES decryption error
+    AESDecryptError
+  | -- CryptoBox decryption error
+    CBDecryptError
+  | -- | message is larger that allowed padded length minus 2 (to prepend message length)
+    -- (or required un-padded length is larger than the message length)
+    CryptoLargeMsgError
+  | -- | failure parsing message header
+    CryptoHeaderError String
+  | -- | no sending chain key in ratchet state
+    CERatchetState
+  | -- | header decryption error (could indicate that another key should be tried)
+    CERatchetHeader
+  | -- | too many skipped messages
+    CERatchetTooManySkipped
+  | -- | duplicate message number (or, possibly, skipped message that failed to decrypt?)
+    CERatchetDuplicateMessage
+  deriving (Eq, Show, Exception)
+
+aesKeySize :: Int
+aesKeySize = 256 `div` 8
+
+authTagSize :: Int
+authTagSize = 128 `div` 8
+
+x25519_size :: Int
+x25519_size = 32
+
+x448_size :: Int
+x448_size = 448 `quot` 8
+
+validSignatureSize :: Int -> Bool
+validSignatureSize n =
+  n == Ed25519.signatureSize || n == Ed448.signatureSize
+
+-- | AES key newtype.
+newtype Key = Key {unKey :: ByteString}
+  deriving (Eq, Ord, Show)
+
+instance ToField Key where toField = toField . unKey
+
+instance FromField Key where fromField f = Key <$> fromField f
+
+instance ToJSON Key where
+  toJSON = strToJSON . unKey
+  toEncoding = strToJEncoding . unKey
+
+instance FromJSON Key where
+  parseJSON = fmap Key . strParseJSON "Key"
+
+-- | IV bytes newtype.
+newtype IV = IV {unIV :: ByteString}
+
+instance Encoding IV where
+  smpEncode = unIV
+  smpP = IV <$> A.take (ivSize @AES256)
+
+newtype AuthTag = AuthTag {unAuthTag :: AES.AuthTag}
+
+instance Encoding AuthTag where
+  smpEncode = B.pack . map w2c . BA.unpack . AES.unAuthTag . unAuthTag
+  smpP = AuthTag . AES.AuthTag . BA.pack . map c2w . B.unpack <$> A.take authTagSize
+
+-- | Certificate fingerpint newtype.
+--
+-- Previously was used for server's public key hash in ad-hoc transport scheme, kept as is for compatibility.
+newtype KeyHash = KeyHash {unKeyHash :: ByteString} deriving (Eq, Ord, Show)
+
+instance Encoding KeyHash where
+  smpEncode = smpEncode . unKeyHash
+  smpP = KeyHash <$> smpP
+
+instance StrEncoding KeyHash where
+  strEncode = strEncode . unKeyHash
+  strP = KeyHash <$> strP
+
+instance IsString KeyHash where
+  fromString = parseString $ parseAll strP
+
+instance ToField KeyHash where toField = toField . strEncode
+
+instance FromField KeyHash where fromField = blobFieldDecoder $ parseAll strP
+
+-- | SHA256 digest.
+sha256Hash :: ByteString -> ByteString
+sha256Hash = BA.convert . (hash :: ByteString -> Digest SHA256)
+
+-- | AEAD-GCM encryption with empty associated data.
+--
+-- Used as part of hybrid E2E encryption scheme and for SMP transport blocks encryption.
+encryptAES :: Key -> IV -> Int -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
+encryptAES key iv paddedLen = encryptAEAD key iv paddedLen ""
+
+-- | AEAD-GCM encryption.
+--
+-- Used as part of hybrid E2E encryption scheme and for SMP transport blocks encryption.
+encryptAEAD :: Key -> IV -> Int -> ByteString -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
+encryptAEAD aesKey ivBytes paddedLen ad msg = do
+  aead <- initAEAD @AES256 aesKey ivBytes
+  msg' <- liftEither $ pad msg paddedLen
+  pure . first AuthTag $ AES.aeadSimpleEncrypt aead ad msg' authTagSize
+
+-- | AEAD-GCM decryption with empty associated data.
+--
+-- Used as part of hybrid E2E encryption scheme and for SMP transport blocks decryption.
+decryptAES :: Key -> IV -> ByteString -> AuthTag -> ExceptT CryptoError IO ByteString
+decryptAES key iv = decryptAEAD key iv ""
+
+-- | AEAD-GCM decryption.
+--
+-- Used as part of hybrid E2E encryption scheme and for SMP transport blocks decryption.
+decryptAEAD :: Key -> IV -> ByteString -> ByteString -> AuthTag -> ExceptT CryptoError IO ByteString
+decryptAEAD aesKey ivBytes ad msg (AuthTag authTag) = do
+  aead <- initAEAD @AES256 aesKey ivBytes
+  liftEither . unPad =<< maybeError AESDecryptError (AES.aeadSimpleDecrypt aead ad msg authTag)
+
+pad :: ByteString -> Int -> Either CryptoError ByteString
+pad msg paddedLen
+  | padLen >= 0 = Right $ encodeWord16 (fromIntegral len) <> msg <> B.replicate padLen '#'
+  | otherwise = Left CryptoLargeMsgError
+  where
+    len = B.length msg
+    padLen = paddedLen - len - 2
+
+unPad :: ByteString -> Either CryptoError ByteString
+unPad padded
+  | B.length rest >= len = Right $ B.take len rest
+  | otherwise = Left CryptoLargeMsgError
+  where
+    (lenWrd, rest) = B.splitAt 2 padded
+    len = fromIntegral $ decodeWord16 lenWrd
+
+initAEAD :: forall c. AES.BlockCipher c => Key -> IV -> ExceptT CryptoError IO (AES.AEAD c)
+initAEAD (Key aesKey) (IV ivBytes) = do
+  iv <- makeIV @c ivBytes
+  cryptoFailable $ do
+    cipher <- AES.cipherInit aesKey
+    AES.aeadInit AES.AEAD_GCM cipher iv
+
+-- | Random AES256 key.
+randomAesKey :: IO Key
+randomAesKey = Key <$> getRandomBytes aesKeySize
+
+-- | Random IV bytes for AES256 encryption.
+randomIV :: IO IV
+randomIV = IV <$> getRandomBytes (ivSize @AES256)
+
+ivSize :: forall c. AES.BlockCipher c => Int
+ivSize = AES.blockSize (undefined :: c)
+
+makeIV :: AES.BlockCipher c => ByteString -> ExceptT CryptoError IO (AES.IV c)
+makeIV bs = maybeError CryptoIVError $ AES.makeIV bs
+
+maybeError :: CryptoError -> Maybe a -> ExceptT CryptoError IO a
+maybeError e = maybe (throwE e) return
+
+cryptoFailable :: CE.CryptoFailable a -> ExceptT CryptoError IO a
+cryptoFailable = liftEither . first AESCipherError . CE.eitherCryptoError
+
+-- | Message signing.
+--
+-- Used by SMP clients to sign SMP commands and by SMP agents to sign messages.
+sign' :: SignatureAlgorithm a => PrivateKey a -> ByteString -> ExceptT CryptoError IO (Signature a)
+sign' (PrivateKeyEd25519 pk k) msg = pure . SignatureEd25519 $ Ed25519.sign pk k msg
+sign' (PrivateKeyEd448 pk k) msg = pure . SignatureEd448 $ Ed448.sign pk k msg
+
+sign :: APrivateSignKey -> ByteString -> ExceptT CryptoError IO ASignature
+sign (APrivateSignKey a k) = fmap (ASignature a) . sign' k
+
+-- | Signature verification.
+--
+-- Used by SMP servers to authorize SMP commands and by SMP agents to verify messages.
+verify' :: SignatureAlgorithm a => PublicKey a -> Signature a -> ByteString -> Bool
+verify' (PublicKeyEd25519 k) (SignatureEd25519 sig) msg = Ed25519.verify k msg sig
+verify' (PublicKeyEd448 k) (SignatureEd448 sig) msg = Ed448.verify k msg sig
+
+verify :: APublicVerifyKey -> ASignature -> ByteString -> Bool
+verify (APublicVerifyKey a k) (ASignature a' sig) msg = case testEquality a a' of
+  Just Refl -> verify' k sig msg
+  _ -> False
+
+dh' :: DhAlgorithm a => PublicKey a -> PrivateKey a -> DhSecret a
+dh' (PublicKeyX25519 k) (PrivateKeyX25519 pk _) = DhSecretX25519 $ X25519.dh k pk
+dh' (PublicKeyX448 k) (PrivateKeyX448 pk _) = DhSecretX448 $ X448.dh k pk
+
+-- | NaCl @crypto_box@ encrypt with a shared DH secret and 192-bit nonce.
+cbEncrypt :: DhSecret X25519 -> CbNonce -> ByteString -> Int -> Either CryptoError ByteString
+cbEncrypt secret (CbNonce nonce) msg paddedLen = cryptoBox <$> pad msg paddedLen
+  where
+    cryptoBox s = BA.convert tag <> c
+      where
+        (rs, c) = xSalsa20 secret nonce s
+        tag = Poly1305.auth rs c
+
+-- | NaCl @crypto_box@ decrypt with a shared DH secret and 192-bit nonce.
+cbDecrypt :: DhSecret X25519 -> CbNonce -> ByteString -> Either CryptoError ByteString
+cbDecrypt secret (CbNonce nonce) packet
+  | B.length packet < 16 = Left CBDecryptError
+  | BA.constEq tag' tag = unPad msg
+  | otherwise = Left CBDecryptError
+  where
+    (tag', c) = B.splitAt 16 packet
+    (rs, msg) = xSalsa20 secret nonce c
+    tag = Poly1305.auth rs c
+
+newtype CbNonce = CbNonce {unCbNonce :: ByteString}
+  deriving (Show)
+
+instance StrEncoding CbNonce where
+  strEncode (CbNonce s) = strEncode s
+  strP = cbNonce <$> strP
+
+instance ToJSON CbNonce where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+cbNonce :: ByteString -> CbNonce
+cbNonce s
+  | len == 24 = CbNonce s
+  | len > 24 = CbNonce . fst $ B.splitAt 24 s
+  | otherwise = CbNonce $ s <> B.replicate (24 - len) (toEnum 0)
+  where
+    len = B.length s
+
+randomCbNonce :: IO CbNonce
+randomCbNonce = CbNonce <$> getRandomBytes 24
+
+pseudoRandomCbNonce :: TVar ChaChaDRG -> STM CbNonce
+pseudoRandomCbNonce gVar = CbNonce <$> pseudoRandomBytes 24 gVar
+
+pseudoRandomBytes :: Int -> TVar ChaChaDRG -> STM ByteString
+pseudoRandomBytes n gVar = do
+  g <- readTVar gVar
+  let (bytes, g') = randomBytesGenerate n g
+  writeTVar gVar g'
+  return bytes
+
+instance Encoding CbNonce where
+  smpEncode = unCbNonce
+  smpP = CbNonce <$> A.take 24
+
+xSalsa20 :: DhSecret X25519 -> ByteString -> ByteString -> (ByteString, ByteString)
+xSalsa20 (DhSecretX25519 shared) nonce msg = (rs, msg')
+  where
+    zero = B.replicate 16 $ toEnum 0
+    (iv0, iv1) = B.splitAt 8 nonce
+    state0 = XSalsa.initialize 20 shared (zero `B.append` iv0)
+    state1 = XSalsa.derive state0 iv1
+    (rs, state2) = XSalsa.generate state1 32
+    (msg', _) = XSalsa.combine state2 msg
+
+publicToX509 :: PublicKey a -> PubKey
+publicToX509 = \case
+  PublicKeyEd25519 k -> PubKeyEd25519 k
+  PublicKeyEd448 k -> PubKeyEd448 k
+  PublicKeyX25519 k -> PubKeyX25519 k
+  PublicKeyX448 k -> PubKeyX448 k
+
+privateToX509 :: PrivateKey a -> PrivKey
+privateToX509 = \case
+  PrivateKeyEd25519 k _ -> PrivKeyEd25519 k
+  PrivateKeyEd448 k _ -> PrivKeyEd448 k
+  PrivateKeyX25519 k _ -> PrivKeyX25519 k
+  PrivateKeyX448 k _ -> PrivKeyX448 k
+
+encodeASNObj :: ASN1Object a => a -> ByteString
+encodeASNObj k = toStrict . encodeASN1 DER $ toASN1 k []
+
+-- Decoding of binary X509 'CryptoPublicKey'.
+decodePubKey :: CryptoPublicKey k => ByteString -> Either String k
+decodePubKey = decodeKey >=> x509ToPublic >=> pubKey
+
+-- Decoding of binary PKCS8 'PrivateKey'.
+decodePrivKey :: CryptoPrivateKey k => ByteString -> Either String k
+decodePrivKey = decodeKey >=> x509ToPrivate >=> privKey
+
+x509ToPublic :: (PubKey, [ASN1]) -> Either String APublicKey
+x509ToPublic = \case
+  (PubKeyEd25519 k, []) -> Right . APublicKey SEd25519 $ PublicKeyEd25519 k
+  (PubKeyEd448 k, []) -> Right . APublicKey SEd448 $ PublicKeyEd448 k
+  (PubKeyX25519 k, []) -> Right . APublicKey SX25519 $ PublicKeyX25519 k
+  (PubKeyX448 k, []) -> Right . APublicKey SX448 $ PublicKeyX448 k
+  r -> keyError r
+
+x509ToPrivate :: (PrivKey, [ASN1]) -> Either String APrivateKey
+x509ToPrivate = \case
+  (PrivKeyEd25519 k, []) -> Right . APrivateKey SEd25519 . PrivateKeyEd25519 k $ Ed25519.toPublic k
+  (PrivKeyEd448 k, []) -> Right . APrivateKey SEd448 . PrivateKeyEd448 k $ Ed448.toPublic k
+  (PrivKeyX25519 k, []) -> Right . APrivateKey SX25519 . PrivateKeyX25519 k $ X25519.toPublic k
+  (PrivKeyX448 k, []) -> Right . APrivateKey SX448 . PrivateKeyX448 k $ X448.toPublic k
+  r -> keyError r
+
+decodeKey :: ASN1Object a => ByteString -> Either String (a, [ASN1])
+decodeKey = fromASN1 <=< first show . decodeASN1 DER . fromStrict
+
+keyError :: (a, [ASN1]) -> Either String b
+keyError = \case
+  (_, []) -> Left "unknown key algorithm"
+  _ -> Left "more than one key"

src/Simplex/Messaging/Crypto/Ratchet.hs

@@ -0,0 +1,488 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
+
+module Simplex.Messaging.Crypto.Ratchet where
+
+import Control.Monad.Except
+import Control.Monad.Trans.Except
+import Crypto.Cipher.AES (AES256)
+import Crypto.Hash (SHA512)
+import qualified Crypto.KDF.HKDF as H
+import Data.Aeson (FromJSON, ToJSON)
+import qualified Data.Aeson as J
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import qualified Data.ByteString.Lazy as LB
+import qualified Data.List.NonEmpty as L
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Maybe (fromMaybe)
+import Data.Typeable (Typeable)
+import Data.Word (Word32)
+import Database.SQLite.Simple.FromField (FromField (..))
+import Database.SQLite.Simple.ToField (ToField (..))
+import GHC.Generics
+import Simplex.Messaging.Agent.QueryString
+import Simplex.Messaging.Crypto
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Parsers (blobFieldDecoder, parseE, parseE')
+import Simplex.Messaging.Util (tryE)
+import Simplex.Messaging.Version
+
+e2eEncryptVersion :: Version
+e2eEncryptVersion = 1
+
+e2eEncryptVRange :: VersionRange
+e2eEncryptVRange = mkVersionRange 1 e2eEncryptVersion
+
+data E2ERatchetParams (a :: Algorithm)
+  = E2ERatchetParams Version (PublicKey a) (PublicKey a)
+  deriving (Eq, Show)
+
+instance AlgorithmI a => Encoding (E2ERatchetParams a) where
+  smpEncode (E2ERatchetParams v k1 k2) = smpEncode (v, k1, k2)
+  smpP = E2ERatchetParams <$> smpP <*> smpP <*> smpP
+
+instance VersionI (E2ERatchetParams a) where
+  type VersionRangeT (E2ERatchetParams a) = E2ERatchetParamsUri a
+  version (E2ERatchetParams v _ _) = v
+  toVersionRangeT (E2ERatchetParams _ k1 k2) vr = E2ERatchetParamsUri vr k1 k2
+
+instance VersionRangeI (E2ERatchetParamsUri a) where
+  type VersionT (E2ERatchetParamsUri a) = (E2ERatchetParams a)
+  versionRange (E2ERatchetParamsUri vr _ _) = vr
+  toVersionT (E2ERatchetParamsUri _ k1 k2) v = E2ERatchetParams v k1 k2
+
+data E2ERatchetParamsUri (a :: Algorithm)
+  = E2ERatchetParamsUri VersionRange (PublicKey a) (PublicKey a)
+  deriving (Eq, Show)
+
+instance AlgorithmI a => StrEncoding (E2ERatchetParamsUri a) where
+  strEncode (E2ERatchetParamsUri vs key1 key2) =
+    strEncode $
+      QSP QNoEscaping [("v", strEncode vs), ("x3dh", strEncodeList [key1, key2])]
+  strP = do
+    query <- strP
+    vs <- queryParam "v" query
+    keys <- L.toList <$> queryParam "x3dh" query
+    case keys of
+      [key1, key2] -> pure $ E2ERatchetParamsUri vs key1 key2
+      _ -> fail "bad e2e params"
+
+generateE2EParams :: (AlgorithmI a, DhAlgorithm a) => Version -> IO (PrivateKey a, PrivateKey a, E2ERatchetParams a)
+generateE2EParams v = do
+  (k1, pk1) <- generateKeyPair'
+  (k2, pk2) <- generateKeyPair'
+  pure (pk1, pk2, E2ERatchetParams v k1 k2)
+
+data RatchetInitParams = RatchetInitParams
+  { assocData :: Str,
+    ratchetKey :: RatchetKey,
+    sndHK :: HeaderKey,
+    rcvNextHK :: HeaderKey
+  }
+  deriving (Eq, Show)
+
+x3dhSnd :: DhAlgorithm a => PrivateKey a -> PrivateKey a -> E2ERatchetParams a -> RatchetInitParams
+x3dhSnd spk1 spk2 (E2ERatchetParams _ rk1 rk2) =
+  x3dh (publicKey spk1, rk1) (dh' rk1 spk2) (dh' rk2 spk1) (dh' rk2 spk2)
+
+x3dhRcv :: DhAlgorithm a => PrivateKey a -> PrivateKey a -> E2ERatchetParams a -> RatchetInitParams
+x3dhRcv rpk1 rpk2 (E2ERatchetParams _ sk1 sk2) =
+  x3dh (sk1, publicKey rpk1) (dh' sk2 rpk1) (dh' sk1 rpk2) (dh' sk2 rpk2)
+
+x3dh :: DhAlgorithm a => (PublicKey a, PublicKey a) -> DhSecret a -> DhSecret a -> DhSecret a -> RatchetInitParams
+x3dh (sk1, rk1) dh1 dh2 dh3 =
+  RatchetInitParams {assocData, ratchetKey = RatchetKey sk, sndHK = Key hk, rcvNextHK = Key nhk}
+  where
+    assocData = Str $ pubKeyBytes sk1 <> pubKeyBytes rk1
+    (hk, rest) = B.splitAt 32 $ dhBytes' dh1 <> dhBytes' dh2 <> dhBytes' dh3
+    (nhk, sk) = B.splitAt 32 rest
+
+type RatchetX448 = Ratchet 'X448
+
+data Ratchet a = Ratchet
+  { -- ratchet version range sent in messages (current .. max supported ratchet version)
+    rcVersion :: VersionRange,
+    -- associated data - must be the same in both parties ratchets
+    rcAD :: Str,
+    rcDHRs :: PrivateKey a,
+    rcRK :: RatchetKey,
+    rcSnd :: Maybe (SndRatchet a),
+    rcRcv :: Maybe RcvRatchet,
+    rcNs :: Word32,
+    rcNr :: Word32,
+    rcPN :: Word32,
+    rcNHKs :: HeaderKey,
+    rcNHKr :: HeaderKey
+  }
+  deriving (Eq, Show, Generic, FromJSON)
+
+instance AlgorithmI a => ToJSON (Ratchet a) where
+  toEncoding = J.genericToEncoding J.defaultOptions
+
+data SndRatchet a = SndRatchet
+  { rcDHRr :: PublicKey a,
+    rcCKs :: RatchetKey,
+    rcHKs :: HeaderKey
+  }
+  deriving (Eq, Show, Generic, FromJSON)
+
+instance AlgorithmI a => ToJSON (SndRatchet a) where
+  toEncoding = J.genericToEncoding J.defaultOptions
+
+data RcvRatchet = RcvRatchet
+  { rcCKr :: RatchetKey,
+    rcHKr :: HeaderKey
+  }
+  deriving (Eq, Show, Generic, FromJSON)
+
+instance ToJSON RcvRatchet where
+  toEncoding = J.genericToEncoding J.defaultOptions
+
+type SkippedMsgKeys = Map HeaderKey SkippedHdrMsgKeys
+
+type SkippedHdrMsgKeys = Map Word32 MessageKey
+
+data SkippedMsgDiff
+  = SMDNoChange
+  | SMDRemove HeaderKey Word32
+  | SMDAdd SkippedMsgKeys
+
+-- | this function is only used in tests to apply changes in skipped messages,
+-- in the agent the diff is persisted, and the whole state is loaded for the next message.
+applySMDiff :: SkippedMsgKeys -> SkippedMsgDiff -> SkippedMsgKeys
+applySMDiff smks = \case
+  SMDNoChange -> smks
+  SMDRemove hk msgN -> fromMaybe smks $ do
+    mks <- M.lookup hk smks
+    _ <- M.lookup msgN mks
+    let mks' = M.delete msgN mks
+    pure $
+      if M.null mks'
+        then M.delete hk smks
+        else M.insert hk mks' smks
+  SMDAdd smks' ->
+    let merge hk mks = M.alter (Just . maybe mks (M.union mks)) hk
+     in M.foldrWithKey merge smks smks'
+
+type HeaderKey = Key
+
+data MessageKey = MessageKey Key IV
+
+instance Encoding MessageKey where
+  smpEncode (MessageKey (Key key) (IV iv)) = smpEncode (key, iv)
+  smpP = MessageKey <$> (Key <$> smpP) <*> (IV <$> smpP)
+
+-- | Input key material for double ratchet HKDF functions
+newtype RatchetKey = RatchetKey ByteString
+  deriving (Eq, Show)
+
+instance ToJSON RatchetKey where
+  toJSON (RatchetKey k) = strToJSON k
+  toEncoding (RatchetKey k) = strToJEncoding k
+
+instance FromJSON RatchetKey where
+  parseJSON = fmap RatchetKey . strParseJSON "Key"
+
+instance AlgorithmI a => ToField (Ratchet a) where toField = toField . LB.toStrict . J.encode
+
+instance (AlgorithmI a, Typeable a) => FromField (Ratchet a) where fromField = blobFieldDecoder J.eitherDecodeStrict'
+
+instance ToField MessageKey where toField = toField . smpEncode
+
+instance FromField MessageKey where fromField = blobFieldDecoder smpDecode
+
+-- | Sending ratchet initialization, equivalent to RatchetInitAliceHE in double ratchet spec
+--
+-- Please note that sPKey is not stored, and its public part together with random salt
+-- is sent to the recipient.
+initSndRatchet ::
+  forall a. (AlgorithmI a, DhAlgorithm a) => PublicKey a -> PrivateKey a -> RatchetInitParams -> Ratchet a
+initSndRatchet rcDHRr rcDHRs RatchetInitParams {assocData, ratchetKey, sndHK, rcvNextHK} = do
+  -- state.RK, state.CKs, state.NHKs = KDF_RK_HE(SK, DH(state.DHRs, state.DHRr))
+  let (rcRK, rcCKs, rcNHKs) = rootKdf ratchetKey rcDHRr rcDHRs
+   in Ratchet
+        { rcVersion = e2eEncryptVRange,
+          rcAD = assocData,
+          rcDHRs,
+          rcRK,
+          rcSnd = Just SndRatchet {rcDHRr, rcCKs, rcHKs = sndHK},
+          rcRcv = Nothing,
+          rcPN = 0,
+          rcNs = 0,
+          rcNr = 0,
+          rcNHKs,
+          rcNHKr = rcvNextHK
+        }
+
+-- | Receiving ratchet initialization, equivalent to RatchetInitBobHE in double ratchet spec
+--
+-- Please note that the public part of rcDHRs was sent to the sender
+-- as part of the connection request and random salt was received from the sender.
+initRcvRatchet ::
+  forall a. (AlgorithmI a, DhAlgorithm a) => PrivateKey a -> RatchetInitParams -> Ratchet a
+initRcvRatchet rcDHRs RatchetInitParams {assocData, ratchetKey, sndHK, rcvNextHK} =
+  Ratchet
+    { rcVersion = e2eEncryptVRange,
+      rcAD = assocData,
+      rcDHRs,
+      rcRK = ratchetKey,
+      rcSnd = Nothing,
+      rcRcv = Nothing,
+      rcPN = 0,
+      rcNs = 0,
+      rcNr = 0,
+      rcNHKs = rcvNextHK,
+      rcNHKr = sndHK
+    }
+
+data MsgHeader a = MsgHeader
+  { -- | max supported ratchet version
+    msgMaxVersion :: Version,
+    msgDHRs :: PublicKey a,
+    msgPN :: Word32,
+    msgNs :: Word32
+  }
+  deriving (Eq, Show)
+
+data AMsgHeader
+  = forall a.
+    (AlgorithmI a, DhAlgorithm a) =>
+    AMsgHeader (SAlgorithm a) (MsgHeader a)
+
+-- to allow extension without increasing the size, the actual header length is:
+-- 69 = 2 (original size) + 2 + 1+56 (Curve448) + 4 + 4
+paddedHeaderLen :: Int
+paddedHeaderLen = 88
+
+-- only used in tests to validate correct padding
+-- (2 bytes - version size, 1 byte - header size, not to have it fixed or version-dependent)
+fullHeaderLen :: Int
+fullHeaderLen = 2 + 1 + paddedHeaderLen + authTagSize + ivSize @AES256
+
+instance AlgorithmI a => Encoding (MsgHeader a) where
+  smpEncode MsgHeader {msgMaxVersion, msgDHRs, msgPN, msgNs} =
+    smpEncode (msgMaxVersion, msgDHRs, msgPN, msgNs)
+  smpP = do
+    msgMaxVersion <- smpP
+    msgDHRs <- smpP
+    msgPN <- smpP
+    msgNs <- smpP
+    pure MsgHeader {msgMaxVersion, msgDHRs, msgPN, msgNs}
+
+data EncMessageHeader = EncMessageHeader
+  { ehVersion :: Version,
+    ehIV :: IV,
+    ehAuthTag :: AuthTag,
+    ehBody :: ByteString
+  }
+
+instance Encoding EncMessageHeader where
+  smpEncode EncMessageHeader {ehVersion, ehIV, ehAuthTag, ehBody} =
+    smpEncode (ehVersion, ehIV, ehAuthTag, ehBody)
+  smpP = do
+    (ehVersion, ehIV, ehAuthTag, ehBody) <- smpP
+    pure EncMessageHeader {ehVersion, ehIV, ehAuthTag, ehBody}
+
+data EncRatchetMessage = EncRatchetMessage
+  { emHeader :: ByteString,
+    emAuthTag :: AuthTag,
+    emBody :: ByteString
+  }
+
+instance Encoding EncRatchetMessage where
+  smpEncode EncRatchetMessage {emHeader, emBody, emAuthTag} =
+    smpEncode (emHeader, emAuthTag, Tail emBody)
+  smpP = do
+    (emHeader, emAuthTag, Tail emBody) <- smpP
+    pure EncRatchetMessage {emHeader, emBody, emAuthTag}
+
+rcEncrypt :: AlgorithmI a => Ratchet a -> Int -> ByteString -> ExceptT CryptoError IO (ByteString, Ratchet a)
+rcEncrypt Ratchet {rcSnd = Nothing} _ _ = throwE CERatchetState
+rcEncrypt rc@Ratchet {rcSnd = Just sr@SndRatchet {rcCKs, rcHKs}, rcDHRs, rcNs, rcPN, rcAD = Str rcAD, rcVersion} paddedMsgLen msg = do
+  -- state.CKs, mk = KDF_CK(state.CKs)
+  let (ck', mk, iv, ehIV) = chainKdf rcCKs
+  -- enc_header = HENCRYPT(state.HKs, header)
+  (ehAuthTag, ehBody) <- encryptAEAD rcHKs ehIV paddedHeaderLen rcAD msgHeader
+  -- return enc_header, ENCRYPT(mk, plaintext, CONCAT(AD, enc_header))
+  let emHeader = smpEncode EncMessageHeader {ehVersion = minVersion rcVersion, ehBody, ehAuthTag, ehIV}
+  (emAuthTag, emBody) <- encryptAEAD mk iv paddedMsgLen (rcAD <> emHeader) msg
+  let msg' = smpEncode EncRatchetMessage {emHeader, emBody, emAuthTag}
+      -- state.Ns += 1
+      rc' = rc {rcSnd = Just sr {rcCKs = ck'}, rcNs = rcNs + 1}
+  pure (msg', rc')
+  where
+    -- header = HEADER(state.DHRs, state.PN, state.Ns)
+    msgHeader =
+      smpEncode
+        MsgHeader
+          { msgMaxVersion = maxVersion rcVersion,
+            msgDHRs = publicKey rcDHRs,
+            msgPN = rcPN,
+            msgNs = rcNs
+          }
+
+data SkippedMessage a
+  = SMMessage (DecryptResult a)
+  | SMHeader (Maybe RatchetStep) (MsgHeader a)
+  | SMNone
+
+data RatchetStep = AdvanceRatchet | SameRatchet
+  deriving (Eq)
+
+type DecryptResult a = (Either CryptoError ByteString, Ratchet a, SkippedMsgDiff)
+
+maxSkip :: Word32
+maxSkip = 512
+
+rcDecrypt ::
+  forall a.
+  (AlgorithmI a, DhAlgorithm a) =>
+  Ratchet a ->
+  SkippedMsgKeys ->
+  ByteString ->
+  ExceptT CryptoError IO (DecryptResult a)
+rcDecrypt rc@Ratchet {rcRcv, rcAD = Str rcAD} rcMKSkipped msg' = do
+  encMsg@EncRatchetMessage {emHeader} <- parseE CryptoHeaderError smpP msg'
+  encHdr <- parseE CryptoHeaderError smpP emHeader
+  -- plaintext = TrySkippedMessageKeysHE(state, enc_header, cipher-text, AD)
+  decryptSkipped encHdr encMsg >>= \case
+    SMNone -> do
+      (rcStep, hdr) <- decryptRcHeader rcRcv encHdr
+      decryptRcMessage rcStep hdr encMsg
+    SMHeader rcStep_ hdr ->
+      case rcStep_ of
+        Just rcStep -> decryptRcMessage rcStep hdr encMsg
+        Nothing -> throwE CERatchetHeader
+    SMMessage r -> pure r
+  where
+    decryptRcMessage :: RatchetStep -> MsgHeader a -> EncRatchetMessage -> ExceptT CryptoError IO (DecryptResult a)
+    decryptRcMessage rcStep MsgHeader {msgDHRs, msgPN, msgNs} encMsg = do
+      -- if dh_ratchet:
+      (rc', smks1) <- ratchetStep rcStep
+      case skipMessageKeys msgNs rc' of
+        Left e -> pure (Left e, rc', smkDiff smks1)
+        Right (rc''@Ratchet {rcRcv = Just rr@RcvRatchet {rcCKr}, rcNr}, smks2) -> do
+          -- state.CKr, mk = KDF_CK(state.CKr)
+          let (rcCKr', mk, iv, _) = chainKdf rcCKr
+          -- return DECRYPT (mk, cipher-text, CONCAT (AD, enc_header))
+          msg <- decryptMessage (MessageKey mk iv) encMsg
+          -- state . Nr += 1
+          pure (msg, rc'' {rcRcv = Just rr {rcCKr = rcCKr'}, rcNr = rcNr + 1}, smkDiff $ smks1 <> smks2)
+        Right (rc'', smks2) -> do
+          pure (Left CERatchetState, rc'', smkDiff $ smks1 <> smks2)
+      where
+        smkDiff :: SkippedMsgKeys -> SkippedMsgDiff
+        smkDiff smks = if M.null smks then SMDNoChange else SMDAdd smks
+        ratchetStep :: RatchetStep -> ExceptT CryptoError IO (Ratchet a, SkippedMsgKeys)
+        ratchetStep SameRatchet = pure (rc, M.empty)
+        ratchetStep AdvanceRatchet =
+          -- SkipMessageKeysHE(state, header.pn)
+          case skipMessageKeys msgPN rc of
+            Left e -> throwE e
+            Right (rc'@Ratchet {rcDHRs, rcRK, rcNHKs, rcNHKr}, hmks) -> do
+              -- DHRatchetHE(state, header)
+              (_, rcDHRs') <- liftIO $ generateKeyPair' @a
+              -- state.RK, state.CKr, state.NHKr = KDF_RK_HE(state.RK, DH(state.DHRs, state.DHRr))
+              let (rcRK', rcCKr', rcNHKr') = rootKdf rcRK msgDHRs rcDHRs
+                  -- state.RK, state.CKs, state.NHKs = KDF_RK_HE(state.RK, DH(state.DHRs, state.DHRr))
+                  (rcRK'', rcCKs', rcNHKs') = rootKdf rcRK' msgDHRs rcDHRs'
+                  rc'' =
+                    rc'
+                      { rcDHRs = rcDHRs',
+                        rcRK = rcRK'',
+                        rcSnd = Just SndRatchet {rcDHRr = msgDHRs, rcCKs = rcCKs', rcHKs = rcNHKs},
+                        rcRcv = Just RcvRatchet {rcCKr = rcCKr', rcHKr = rcNHKr},
+                        rcPN = rcNs rc,
+                        rcNs = 0,
+                        rcNr = 0,
+                        rcNHKs = rcNHKs',
+                        rcNHKr = rcNHKr'
+                      }
+              pure (rc'', hmks)
+    skipMessageKeys :: Word32 -> Ratchet a -> Either CryptoError (Ratchet a, SkippedMsgKeys)
+    skipMessageKeys _ r@Ratchet {rcRcv = Nothing} = Right (r, M.empty)
+    skipMessageKeys untilN r@Ratchet {rcRcv = Just rr@RcvRatchet {rcCKr, rcHKr}, rcNr}
+      | rcNr > untilN = Left CERatchetDuplicateMessage
+      | rcNr + maxSkip < untilN = Left CERatchetTooManySkipped
+      | rcNr == untilN = Right (r, M.empty)
+      | otherwise =
+        let (rcCKr', rcNr', mks) = advanceRcvRatchet (untilN - rcNr) rcCKr rcNr M.empty
+            r' = r {rcRcv = Just rr {rcCKr = rcCKr'}, rcNr = rcNr'}
+         in Right (r', M.singleton rcHKr mks)
+    advanceRcvRatchet :: Word32 -> RatchetKey -> Word32 -> SkippedHdrMsgKeys -> (RatchetKey, Word32, SkippedHdrMsgKeys)
+    advanceRcvRatchet 0 ck msgNs mks = (ck, msgNs, mks)
+    advanceRcvRatchet n ck msgNs mks =
+      let (ck', mk, iv, _) = chainKdf ck
+          mks' = M.insert msgNs (MessageKey mk iv) mks
+       in advanceRcvRatchet (n - 1) ck' (msgNs + 1) mks'
+    decryptSkipped :: EncMessageHeader -> EncRatchetMessage -> ExceptT CryptoError IO (SkippedMessage a)
+    decryptSkipped encHdr encMsg = tryDecryptSkipped SMNone $ M.assocs rcMKSkipped
+      where
+        tryDecryptSkipped :: SkippedMessage a -> [(HeaderKey, SkippedHdrMsgKeys)] -> ExceptT CryptoError IO (SkippedMessage a)
+        tryDecryptSkipped SMNone ((hk, mks) : hks) = do
+          tryE (decryptHeader hk encHdr) >>= \case
+            Left CERatchetHeader -> tryDecryptSkipped SMNone hks
+            Left e -> throwE e
+            Right hdr@MsgHeader {msgNs} ->
+              case M.lookup msgNs mks of
+                Nothing ->
+                  let nextRc
+                        | maybe False ((== hk) . rcHKr) rcRcv = Just SameRatchet
+                        | hk == rcNHKr rc = Just AdvanceRatchet
+                        | otherwise = Nothing
+                   in pure $ SMHeader nextRc hdr
+                Just mk -> do
+                  msg <- decryptMessage mk encMsg
+                  pure $ SMMessage (msg, rc, SMDRemove hk msgNs)
+        tryDecryptSkipped r _ = pure r
+    decryptRcHeader :: Maybe RcvRatchet -> EncMessageHeader -> ExceptT CryptoError IO (RatchetStep, MsgHeader a)
+    decryptRcHeader Nothing hdr = decryptNextHeader hdr
+    decryptRcHeader (Just RcvRatchet {rcHKr}) hdr =
+      -- header = HDECRYPT(state.HKr, enc_header)
+      ((SameRatchet,) <$> decryptHeader rcHKr hdr) `catchE` \case
+        CERatchetHeader -> decryptNextHeader hdr
+        e -> throwE e
+    -- header = HDECRYPT(state.NHKr, enc_header)
+    decryptNextHeader hdr = (AdvanceRatchet,) <$> decryptHeader (rcNHKr rc) hdr
+    decryptHeader k EncMessageHeader {ehBody, ehAuthTag, ehIV} = do
+      header <- decryptAEAD k ehIV rcAD ehBody ehAuthTag `catchE` \_ -> throwE CERatchetHeader
+      parseE' CryptoHeaderError smpP header
+    decryptMessage :: MessageKey -> EncRatchetMessage -> ExceptT CryptoError IO (Either CryptoError ByteString)
+    decryptMessage (MessageKey mk iv) EncRatchetMessage {emHeader, emBody, emAuthTag} =
+      -- DECRYPT(mk, cipher-text, CONCAT(AD, enc_header))
+      -- TODO add associated data
+      tryE $ decryptAEAD mk iv (rcAD <> emHeader) emBody emAuthTag
+
+rootKdf :: (AlgorithmI a, DhAlgorithm a) => RatchetKey -> PublicKey a -> PrivateKey a -> (RatchetKey, RatchetKey, Key)
+rootKdf (RatchetKey rk) k pk =
+  let dhOut = dhBytes' $ dh' k pk
+      (rk', ck, nhk) = hkdf3 rk dhOut "SimpleXRootRatchet"
+   in (RatchetKey rk', RatchetKey ck, Key nhk)
+
+chainKdf :: RatchetKey -> (RatchetKey, Key, IV, IV)
+chainKdf (RatchetKey ck) =
+  let (ck', mk, ivs) = hkdf3 "" ck "SimpleXChainRatchet"
+      (iv1, iv2) = B.splitAt 16 ivs
+   in (RatchetKey ck', Key mk, IV iv1, IV iv2)
+
+hkdf3 :: ByteString -> ByteString -> ByteString -> (ByteString, ByteString, ByteString)
+hkdf3 salt ikm info = (s1, s2, s3)
+  where
+    prk = H.extract salt ikm :: H.PRK SHA512
+    out = H.expand prk info 96
+    (s1, rest) = B.splitAt 32 out
+    (s2, s3) = B.splitAt 32 rest

src/Simplex/Messaging/Encoding.hs

@@ -0,0 +1,147 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE UndecidableInstances #-}
+
+module Simplex.Messaging.Encoding
+  ( Encoding (..),
+    Tail (..),
+    Large (..),
+    smpEncodeList,
+    smpListP,
+  )
+where
+
+import Data.Attoparsec.ByteString.Char8 (Parser)
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.Bits (shiftL, shiftR, (.|.))
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.ByteString.Internal (c2w, w2c)
+import Data.Int (Int64)
+import qualified Data.List.NonEmpty as L
+import Data.Time.Clock.System (SystemTime (..))
+import Data.Word (Word16, Word32)
+import Network.Transport.Internal (decodeWord16, decodeWord32, encodeWord16, encodeWord32)
+import Simplex.Messaging.Parsers (parseAll)
+import Simplex.Messaging.Util ((<$?>))
+
+-- | SMP protocol encoding
+class Encoding a where
+  {-# MINIMAL smpEncode, (smpDecode | smpP) #-}
+
+  -- | protocol encoding of type (default implementation uses protocol ByteString encoding)
+  smpEncode :: a -> ByteString
+
+  -- | decoding of type (default implementation uses parser)
+  smpDecode :: ByteString -> Either String a
+  smpDecode = parseAll smpP
+
+  -- | protocol parser of type (default implementation parses protocol ByteString encoding)
+  smpP :: Parser a
+  smpP = smpDecode <$?> smpP
+
+instance Encoding Char where
+  smpEncode = B.singleton
+  smpP = A.anyChar
+
+instance Encoding Word16 where
+  smpEncode = encodeWord16
+  smpP = decodeWord16 <$> A.take 2
+
+instance Encoding Word32 where
+  smpEncode = encodeWord32
+  smpP = decodeWord32 <$> A.take 4
+
+instance Encoding Int64 where
+  smpEncode i = w32 (i `shiftR` 32) <> w32 i
+  smpP = do
+    l <- w32P
+    r <- w32P
+    pure $ (l `shiftL` 32) .|. r
+
+w32 :: Int64 -> ByteString
+w32 = smpEncode @Word32 . fromIntegral
+
+w32P :: Parser Int64
+w32P = fromIntegral <$> smpP @Word32
+
+-- ByteStrings are assumed no longer than 255 bytes
+instance Encoding ByteString where
+  smpEncode s = B.cons (lenEncode $ B.length s) s
+  smpP = A.take =<< lenP
+
+lenEncode :: Int -> Char
+lenEncode = w2c . fromIntegral
+
+lenP :: Parser Int
+lenP = fromIntegral . c2w <$> A.anyChar
+
+instance Encoding a => Encoding (Maybe a) where
+  smpEncode s = maybe "0" (("1" <>) . smpEncode) s
+  smpP =
+    smpP >>= \case
+      '0' -> pure Nothing
+      '1' -> Just <$> smpP
+      _ -> fail "invalid Maybe tag"
+
+newtype Tail = Tail {unTail :: ByteString}
+
+instance Encoding Tail where
+  smpEncode = unTail
+  smpP = Tail <$> A.takeByteString
+
+-- newtype for encoding/decoding ByteStrings over 255 bytes with 2-bytes length prefix
+newtype Large = Large {unLarge :: ByteString}
+
+instance Encoding Large where
+  smpEncode (Large s) = smpEncode @Word16 (fromIntegral $ B.length s) <> s
+  smpP = do
+    len <- fromIntegral <$> smpP @Word16
+    Large <$> A.take len
+
+instance Encoding SystemTime where
+  smpEncode = smpEncode . systemSeconds
+  smpP = MkSystemTime <$> smpP <*> pure 0
+
+-- lists encode/parse as a sequence of items prefixed with list length (as 1 byte)
+smpEncodeList :: Encoding a => [a] -> ByteString
+smpEncodeList xs = B.cons (lenEncode $ length xs) . B.concat $ map smpEncode xs
+
+smpListP :: Encoding a => Parser [a]
+smpListP = (`A.count` smpP) =<< lenP
+
+instance Encoding String where
+  smpEncode = smpEncode . B.pack
+  smpP = B.unpack <$> smpP
+
+instance Encoding a => Encoding (L.NonEmpty a) where
+  smpEncode = smpEncodeList . L.toList
+  smpP =
+    lenP >>= \case
+      0 -> fail "empty list"
+      n -> L.fromList <$> A.count n smpP
+
+instance (Encoding a, Encoding b) => Encoding (a, b) where
+  smpEncode (a, b) = smpEncode a <> smpEncode b
+  smpP = (,) <$> smpP <*> smpP
+
+instance (Encoding a, Encoding b, Encoding c) => Encoding (a, b, c) where
+  smpEncode (a, b, c) = smpEncode a <> smpEncode b <> smpEncode c
+  smpP = (,,) <$> smpP <*> smpP <*> smpP
+
+instance (Encoding a, Encoding b, Encoding c, Encoding d) => Encoding (a, b, c, d) where
+  smpEncode (a, b, c, d) = smpEncode a <> smpEncode b <> smpEncode c <> smpEncode d
+  smpP = (,,,) <$> smpP <*> smpP <*> smpP <*> smpP
+
+instance (Encoding a, Encoding b, Encoding c, Encoding d, Encoding e) => Encoding (a, b, c, d, e) where
+  smpEncode (a, b, c, d, e) = smpEncode a <> smpEncode b <> smpEncode c <> smpEncode d <> smpEncode e
+  smpP = (,,,,) <$> smpP <*> smpP <*> smpP <*> smpP <*> smpP
+
+instance (Encoding a, Encoding b, Encoding c, Encoding d, Encoding e, Encoding f) => Encoding (a, b, c, d, e, f) where
+  smpEncode (a, b, c, d, e, f) = smpEncode a <> smpEncode b <> smpEncode c <> smpEncode d <> smpEncode e <> smpEncode f
+  smpP = (,,,,,) <$> smpP <*> smpP <*> smpP <*> smpP <*> smpP <*> smpP

src/Simplex/Messaging/Encoding/String.hs

@@ -0,0 +1,136 @@
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Simplex.Messaging.Encoding.String
+  ( TextEncoding (..),
+    StrEncoding (..),
+    Str (..),
+    strP_,
+    strToJSON,
+    strToJEncoding,
+    strParseJSON,
+    base64urlP,
+    strEncodeList,
+    strListP,
+  )
+where
+
+import Control.Applicative (optional)
+import Data.Aeson (FromJSON (..), ToJSON (..))
+import qualified Data.Aeson as J
+import qualified Data.Aeson.Encoding as JE
+import qualified Data.Aeson.Types as JT
+import Data.Attoparsec.ByteString.Char8 (Parser)
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import qualified Data.ByteString.Base64.URL as U
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Char (isAlphaNum)
+import Data.Int (Int64)
+import qualified Data.List.NonEmpty as L
+import Data.Text (Text)
+import Data.Text.Encoding (decodeLatin1, encodeUtf8)
+import Data.Time.Clock.System (SystemTime (..))
+import Data.Word (Word16)
+import Simplex.Messaging.Parsers (parseAll)
+import Simplex.Messaging.Util ((<$?>))
+
+class TextEncoding a where
+  textEncode :: a -> Text
+  textDecode :: Text -> Maybe a
+
+-- | Serializing human-readable and (where possible) URI-friendly strings for SMP and SMP agent protocols
+class StrEncoding a where
+  {-# MINIMAL strEncode, (strDecode | strP) #-}
+  strEncode :: a -> ByteString
+
+  -- Please note - if you only specify strDecode, it will use base64urlP as default parser before decoding the string
+  strDecode :: ByteString -> Either String a
+  strDecode = parseAll strP
+  strP :: Parser a
+  strP = strDecode <$?> base64urlP
+
+-- base64url encoding/decoding of ByteStrings - the parser only allows non-empty strings
+instance StrEncoding ByteString where
+  strEncode = U.encode
+  strDecode = U.decode
+  strP = base64urlP
+
+base64urlP :: Parser ByteString
+base64urlP = do
+  str <- A.takeWhile1 (\c -> isAlphaNum c || c == '-' || c == '_')
+  pad <- A.takeWhile (== '=')
+  either fail pure $ U.decode (str <> pad)
+
+newtype Str = Str {unStr :: ByteString}
+  deriving (Eq, Show)
+
+instance StrEncoding Str where
+  strEncode = unStr
+  strP = Str <$> A.takeTill (== ' ') <* optional A.space
+
+instance ToJSON Str where
+  toJSON (Str s) = strToJSON s
+  toEncoding (Str s) = strToJEncoding s
+
+instance FromJSON Str where
+  parseJSON = fmap Str . strParseJSON "Str"
+
+instance StrEncoding a => StrEncoding (Maybe a) where
+  strEncode = maybe "" strEncode
+  strP = optional strP
+
+instance StrEncoding Word16 where
+  strEncode = B.pack . show
+  strP = A.decimal
+
+instance StrEncoding Int64 where
+  strEncode = B.pack . show
+  strP = A.decimal
+
+instance StrEncoding SystemTime where
+  strEncode = strEncode . systemSeconds
+  strP = MkSystemTime <$> strP <*> pure 0
+
+-- lists encode/parse as comma-separated strings
+strEncodeList :: StrEncoding a => [a] -> ByteString
+strEncodeList = B.intercalate "," . map strEncode
+
+strListP :: StrEncoding a => Parser [a]
+strListP = listItem `A.sepBy'` A.char ','
+
+-- relies on sepBy1 never returning an empty list
+instance StrEncoding a => StrEncoding (L.NonEmpty a) where
+  strEncode = strEncodeList . L.toList
+  strP = L.fromList <$> listItem `A.sepBy1'` A.char ','
+
+listItem :: StrEncoding a => Parser a
+listItem = parseAll strP <$?> A.takeTill (== ',')
+
+instance (StrEncoding a, StrEncoding b) => StrEncoding (a, b) where
+  strEncode (a, b) = B.unwords [strEncode a, strEncode b]
+  strP = (,) <$> strP_ <*> strP
+
+instance (StrEncoding a, StrEncoding b, StrEncoding c) => StrEncoding (a, b, c) where
+  strEncode (a, b, c) = B.unwords [strEncode a, strEncode b, strEncode c]
+  strP = (,,) <$> strP_ <*> strP_ <*> strP
+
+instance (StrEncoding a, StrEncoding b, StrEncoding c, StrEncoding d) => StrEncoding (a, b, c, d) where
+  strEncode (a, b, c, d) = B.unwords [strEncode a, strEncode b, strEncode c, strEncode d]
+  strP = (,,,) <$> strP_ <*> strP_ <*> strP_ <*> strP
+
+instance (StrEncoding a, StrEncoding b, StrEncoding c, StrEncoding d, StrEncoding e) => StrEncoding (a, b, c, d, e) where
+  strEncode (a, b, c, d, e) = B.unwords [strEncode a, strEncode b, strEncode c, strEncode d, strEncode e]
+  strP = (,,,,) <$> strP_ <*> strP_ <*> strP_ <*> strP_ <*> strP
+
+strP_ :: StrEncoding a => Parser a
+strP_ = strP <* A.space
+
+strToJSON :: StrEncoding a => a -> J.Value
+strToJSON = J.String . decodeLatin1 . strEncode
+
+strToJEncoding :: StrEncoding a => a -> J.Encoding
+strToJEncoding = JE.text . decodeLatin1 . strEncode
+
+strParseJSON :: StrEncoding a => String -> J.Value -> JT.Parser a
+strParseJSON name = J.withText name $ either fail pure . parseAll strP . encodeUtf8

src/Simplex/Messaging/Notifications/Client.hs

@@ -0,0 +1,132 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Simplex.Messaging.Notifications.Client where
+
+import Control.Monad.Except
+import Control.Monad.Trans.Except
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.Word (Word16)
+import Database.SQLite.Simple.FromField (FromField (..))
+import Database.SQLite.Simple.ToField (ToField (..))
+import Simplex.Messaging.Client
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Notifications.Protocol
+import Simplex.Messaging.Parsers (blobFieldDecoder)
+import Simplex.Messaging.Protocol (ProtocolServer)
+
+type NtfServer = ProtocolServer
+
+type NtfClient = ProtocolClient NtfResponse
+
+ntfRegisterToken :: NtfClient -> C.APrivateSignKey -> NewNtfEntity 'Token -> ExceptT ProtocolClientError IO (NtfTokenId, C.PublicKeyX25519)
+ntfRegisterToken c pKey newTkn =
+  sendNtfCommand c (Just pKey) "" (TNEW newTkn) >>= \case
+    NRId tknId dhKey -> pure (tknId, dhKey)
+    _ -> throwE PCEUnexpectedResponse
+
+ntfVerifyToken :: NtfClient -> C.APrivateSignKey -> NtfTokenId -> NtfRegCode -> ExceptT ProtocolClientError IO ()
+ntfVerifyToken c pKey tknId code = okNtfCommand (TVFY code) c pKey tknId
+
+ntfCheckToken :: NtfClient -> C.APrivateSignKey -> NtfTokenId -> ExceptT ProtocolClientError IO NtfTknStatus
+ntfCheckToken c pKey tknId =
+  sendNtfCommand c (Just pKey) tknId TCHK >>= \case
+    NRTkn stat -> pure stat
+    _ -> throwE PCEUnexpectedResponse
+
+ntfDeleteToken :: NtfClient -> C.APrivateSignKey -> NtfTokenId -> ExceptT ProtocolClientError IO ()
+ntfDeleteToken = okNtfCommand TDEL
+
+ntfEnableCron :: NtfClient -> C.APrivateSignKey -> NtfTokenId -> Word16 -> ExceptT ProtocolClientError IO ()
+ntfEnableCron c pKey tknId int = okNtfCommand (TCRN int) c pKey tknId
+
+ntfCreateSubsciption :: NtfClient -> C.APrivateSignKey -> NewNtfEntity 'Subscription -> ExceptT ProtocolClientError IO (NtfSubscriptionId, C.PublicKeyX25519)
+ntfCreateSubsciption c pKey newSub =
+  sendNtfCommand c (Just pKey) "" (SNEW newSub) >>= \case
+    NRId subId dhKey -> pure (subId, dhKey)
+    _ -> throwE PCEUnexpectedResponse
+
+ntfCheckSubscription :: NtfClient -> C.APrivateSignKey -> NtfSubscriptionId -> ExceptT ProtocolClientError IO NtfSubStatus
+ntfCheckSubscription c pKey subId =
+  sendNtfCommand c (Just pKey) subId SCHK >>= \case
+    NRSub stat -> pure stat
+    _ -> throwE PCEUnexpectedResponse
+
+ntfDeleteSubscription :: NtfClient -> C.APrivateSignKey -> NtfSubscriptionId -> ExceptT ProtocolClientError IO ()
+ntfDeleteSubscription = okNtfCommand SDEL
+
+-- | Send notification server command
+sendNtfCommand :: NtfEntityI e => NtfClient -> Maybe C.APrivateSignKey -> NtfEntityId -> NtfCommand e -> ExceptT ProtocolClientError IO NtfResponse
+sendNtfCommand c pKey entId cmd = sendProtocolCommand c pKey entId (NtfCmd sNtfEntity cmd)
+
+okNtfCommand :: NtfEntityI e => NtfCommand e -> NtfClient -> C.APrivateSignKey -> NtfEntityId -> ExceptT ProtocolClientError IO ()
+okNtfCommand cmd c pKey entId =
+  sendNtfCommand c (Just pKey) entId cmd >>= \case
+    NROk -> return ()
+    _ -> throwE PCEUnexpectedResponse
+
+data NtfTknAction
+  = NTARegister
+  | NTAVerify NtfRegCode -- code to verify token
+  | NTACheck
+  | NTACron Word16
+  | NTADelete
+  deriving (Show)
+
+instance Encoding NtfTknAction where
+  smpEncode = \case
+    NTARegister -> "R"
+    NTAVerify code -> smpEncode ('V', code)
+    NTACheck -> "C"
+    NTACron interval -> smpEncode ('I', interval)
+    NTADelete -> "D"
+  smpP =
+    A.anyChar >>= \case
+      'R' -> pure NTARegister
+      'V' -> NTAVerify <$> smpP
+      'C' -> pure NTACheck
+      'I' -> NTACron <$> smpP
+      'D' -> pure NTADelete
+      _ -> fail "bad NtfTknAction"
+
+instance FromField NtfTknAction where fromField = blobFieldDecoder smpDecode
+
+instance ToField NtfTknAction where toField = toField . smpEncode
+
+data NtfToken = NtfToken
+  { deviceToken :: DeviceToken,
+    ntfServer :: NtfServer,
+    ntfTokenId :: Maybe NtfTokenId,
+    -- | key used by the ntf server to verify transmissions
+    ntfPubKey :: C.APublicVerifyKey,
+    -- | key used by the ntf client to sign transmissions
+    ntfPrivKey :: C.APrivateSignKey,
+    -- | client's DH keys (to repeat registration if necessary)
+    ntfDhKeys :: C.KeyPair 'C.X25519,
+    -- | shared DH secret used to encrypt/decrypt notifications e2e
+    ntfDhSecret :: Maybe C.DhSecretX25519,
+    -- | token status
+    ntfTknStatus :: NtfTknStatus,
+    -- | pending token action and the earliest time
+    ntfTknAction :: Maybe NtfTknAction
+  }
+  deriving (Show)
+
+newNtfToken :: DeviceToken -> NtfServer -> C.ASignatureKeyPair -> C.KeyPair 'C.X25519 -> NtfToken
+newNtfToken deviceToken ntfServer (ntfPubKey, ntfPrivKey) ntfDhKeys =
+  NtfToken
+    { deviceToken,
+      ntfServer,
+      ntfTokenId = Nothing,
+      ntfPubKey,
+      ntfPrivKey,
+      ntfDhKeys,
+      ntfDhSecret = Nothing,
+      ntfTknStatus = NTNew,
+      ntfTknAction = Just NTARegister
+    }

src/Simplex/Messaging/Notifications/Protocol.hs

@@ -0,0 +1,434 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module Simplex.Messaging.Notifications.Protocol where
+
+import Data.Aeson (FromJSON (..), ToJSON (..))
+import qualified Data.Aeson as J
+import qualified Data.Aeson.Encoding as JE
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Kind
+import Data.Maybe (isNothing)
+import Data.Text.Encoding (decodeLatin1, encodeUtf8)
+import Data.Type.Equality
+import Data.Word (Word16)
+import Database.SQLite.Simple.FromField (FromField (..))
+import Database.SQLite.Simple.ToField (ToField (..))
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Notifications.Transport (ntfClientHandshake)
+import Simplex.Messaging.Parsers (fromTextField_)
+import Simplex.Messaging.Protocol hiding (Command (..), CommandTag (..))
+import Simplex.Messaging.Util ((<$?>))
+
+data NtfEntity = Token | Subscription
+  deriving (Show)
+
+data SNtfEntity :: NtfEntity -> Type where
+  SToken :: SNtfEntity 'Token
+  SSubscription :: SNtfEntity 'Subscription
+
+instance TestEquality SNtfEntity where
+  testEquality SToken SToken = Just Refl
+  testEquality SSubscription SSubscription = Just Refl
+  testEquality _ _ = Nothing
+
+deriving instance Show (SNtfEntity e)
+
+class NtfEntityI (e :: NtfEntity) where sNtfEntity :: SNtfEntity e
+
+instance NtfEntityI 'Token where sNtfEntity = SToken
+
+instance NtfEntityI 'Subscription where sNtfEntity = SSubscription
+
+data NtfCommandTag (e :: NtfEntity) where
+  TNEW_ :: NtfCommandTag 'Token
+  TVFY_ :: NtfCommandTag 'Token
+  TCHK_ :: NtfCommandTag 'Token
+  TDEL_ :: NtfCommandTag 'Token
+  TCRN_ :: NtfCommandTag 'Token
+  SNEW_ :: NtfCommandTag 'Subscription
+  SCHK_ :: NtfCommandTag 'Subscription
+  SDEL_ :: NtfCommandTag 'Subscription
+  PING_ :: NtfCommandTag 'Subscription
+
+deriving instance Show (NtfCommandTag e)
+
+data NtfCmdTag = forall e. NtfEntityI e => NCT (SNtfEntity e) (NtfCommandTag e)
+
+instance NtfEntityI e => Encoding (NtfCommandTag e) where
+  smpEncode = \case
+    TNEW_ -> "TNEW"
+    TVFY_ -> "TVFY"
+    TCHK_ -> "TCHK"
+    TDEL_ -> "TDEL"
+    TCRN_ -> "TCRN"
+    SNEW_ -> "SNEW"
+    SCHK_ -> "SCHK"
+    SDEL_ -> "SDEL"
+    PING_ -> "PING"
+  smpP = messageTagP
+
+instance Encoding NtfCmdTag where
+  smpEncode (NCT _ t) = smpEncode t
+  smpP = messageTagP
+
+instance ProtocolMsgTag NtfCmdTag where
+  decodeTag = \case
+    "TNEW" -> Just $ NCT SToken TNEW_
+    "TVFY" -> Just $ NCT SToken TVFY_
+    "TCHK" -> Just $ NCT SToken TCHK_
+    "TDEL" -> Just $ NCT SToken TDEL_
+    "TCRN" -> Just $ NCT SToken TCRN_
+    "SNEW" -> Just $ NCT SSubscription SNEW_
+    "SCHK" -> Just $ NCT SSubscription SCHK_
+    "SDEL" -> Just $ NCT SSubscription SDEL_
+    "PING" -> Just $ NCT SSubscription PING_
+    _ -> Nothing
+
+instance NtfEntityI e => ProtocolMsgTag (NtfCommandTag e) where
+  decodeTag s = decodeTag s >>= (\(NCT _ t) -> checkEntity' t)
+
+newtype NtfRegCode = NtfRegCode ByteString
+  deriving (Eq, Show)
+
+instance Encoding NtfRegCode where
+  smpEncode (NtfRegCode code) = smpEncode code
+  smpP = NtfRegCode <$> smpP
+
+instance StrEncoding NtfRegCode where
+  strEncode (NtfRegCode m) = strEncode m
+  strDecode s = NtfRegCode <$> strDecode s
+  strP = NtfRegCode <$> strP
+
+instance FromJSON NtfRegCode where
+  parseJSON = strParseJSON "NtfRegCode"
+
+instance ToJSON NtfRegCode where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+data NewNtfEntity (e :: NtfEntity) where
+  NewNtfTkn :: DeviceToken -> C.APublicVerifyKey -> C.PublicKeyX25519 -> NewNtfEntity 'Token
+  NewNtfSub :: NtfTokenId -> SMPQueueNtf -> NewNtfEntity 'Subscription -- NtfTokenId -> C.APublicVerifyKey -> SMPQueueNtf
+
+deriving instance Show (NewNtfEntity e)
+
+data ANewNtfEntity = forall e. NtfEntityI e => ANE (SNtfEntity e) (NewNtfEntity e)
+
+instance NtfEntityI e => Encoding (NewNtfEntity e) where
+  smpEncode = \case
+    NewNtfTkn tkn verifyKey dhPubKey -> smpEncode ('T', tkn, verifyKey, dhPubKey)
+    NewNtfSub tknId smpQueue -> smpEncode ('S', tknId, smpQueue)
+  smpP = (\(ANE _ c) -> checkEntity c) <$?> smpP
+
+instance Encoding ANewNtfEntity where
+  smpEncode (ANE _ e) = smpEncode e
+  smpP =
+    A.anyChar >>= \case
+      'T' -> ANE SToken <$> (NewNtfTkn <$> smpP <*> smpP <*> smpP)
+      'S' -> ANE SSubscription <$> (NewNtfSub <$> smpP <*> smpP)
+      _ -> fail "bad ANewNtfEntity"
+
+instance Protocol NtfResponse where
+  type ProtocolCommand NtfResponse = NtfCmd
+  protocolClientHandshake = ntfClientHandshake
+  protocolPing = NtfCmd SSubscription PING
+  protocolError = \case
+    NRErr e -> Just e
+    _ -> Nothing
+
+data NtfCommand (e :: NtfEntity) where
+  -- | register new device token for notifications
+  TNEW :: NewNtfEntity 'Token -> NtfCommand 'Token
+  -- | verify token - uses e2e encrypted random string sent to the device via PN to confirm that the device has the token
+  TVFY :: NtfRegCode -> NtfCommand 'Token
+  -- | check token status
+  TCHK :: NtfCommand 'Token
+  -- | delete token - all subscriptions will be removed and no more notifications will be sent
+  TDEL :: NtfCommand 'Token
+  -- | enable periodic background notification to fetch the new messages - interval is in minutes, minimum is 20, 0 to disable
+  TCRN :: Word16 -> NtfCommand 'Token
+  -- | create SMP subscription
+  SNEW :: NewNtfEntity 'Subscription -> NtfCommand 'Subscription
+  -- | check SMP subscription status (response is STAT)
+  SCHK :: NtfCommand 'Subscription
+  -- | delete SMP subscription
+  SDEL :: NtfCommand 'Subscription
+  -- | keep-alive command
+  PING :: NtfCommand 'Subscription
+
+deriving instance Show (NtfCommand e)
+
+data NtfCmd = forall e. NtfEntityI e => NtfCmd (SNtfEntity e) (NtfCommand e)
+
+deriving instance Show NtfCmd
+
+instance NtfEntityI e => ProtocolEncoding (NtfCommand e) where
+  type Tag (NtfCommand e) = NtfCommandTag e
+  encodeProtocol = \case
+    TNEW newTkn -> e (TNEW_, ' ', newTkn)
+    TVFY code -> e (TVFY_, ' ', code)
+    TCHK -> e TCHK_
+    TDEL -> e TDEL_
+    TCRN int -> e (TCRN_, ' ', int)
+    SNEW newSub -> e (SNEW_, ' ', newSub)
+    SCHK -> e SCHK_
+    SDEL -> e SDEL_
+    PING -> e PING_
+    where
+      e :: Encoding a => a -> ByteString
+      e = smpEncode
+
+  protocolP tag = (\(NtfCmd _ c) -> checkEntity c) <$?> protocolP (NCT (sNtfEntity @e) tag)
+
+  checkCredentials (sig, _, entityId, _) cmd = case cmd of
+    -- TNEW and SNEW must have signature but NOT token/subscription IDs
+    TNEW {} -> sigNoEntity
+    SNEW {} -> sigNoEntity
+    PING
+      | isNothing sig && B.null entityId -> Right cmd
+      | otherwise -> Left $ CMD HAS_AUTH
+    -- other client commands must have both signature and entity ID
+    _
+      | isNothing sig || B.null entityId -> Left $ CMD NO_AUTH
+      | otherwise -> Right cmd
+    where
+      sigNoEntity
+        | isNothing sig = Left $ CMD NO_AUTH
+        | not (B.null entityId) = Left $ CMD HAS_AUTH
+        | otherwise = Right cmd
+
+instance ProtocolEncoding NtfCmd where
+  type Tag NtfCmd = NtfCmdTag
+  encodeProtocol (NtfCmd _ c) = encodeProtocol c
+
+  protocolP = \case
+    NCT SToken tag ->
+      NtfCmd SToken <$> case tag of
+        TNEW_ -> TNEW <$> _smpP
+        TVFY_ -> TVFY <$> _smpP
+        TCHK_ -> pure TCHK
+        TDEL_ -> pure TDEL
+        TCRN_ -> TCRN <$> _smpP
+    NCT SSubscription tag ->
+      NtfCmd SSubscription <$> case tag of
+        SNEW_ -> SNEW <$> _smpP
+        SCHK_ -> pure SCHK
+        SDEL_ -> pure SDEL
+        PING_ -> pure PING
+
+  checkCredentials t (NtfCmd e c) = NtfCmd e <$> checkCredentials t c
+
+data NtfResponseTag
+  = NRId_
+  | NROk_
+  | NRErr_
+  | NRTkn_
+  | NRSub_
+  | NRPong_
+  deriving (Show)
+
+instance Encoding NtfResponseTag where
+  smpEncode = \case
+    NRId_ -> "ID"
+    NROk_ -> "OK"
+    NRErr_ -> "ERR"
+    NRTkn_ -> "TKN"
+    NRSub_ -> "SUB"
+    NRPong_ -> "PONG"
+  smpP = messageTagP
+
+instance ProtocolMsgTag NtfResponseTag where
+  decodeTag = \case
+    "ID" -> Just NRId_
+    "OK" -> Just NROk_
+    "ERR" -> Just NRErr_
+    "TKN" -> Just NRTkn_
+    "SUB" -> Just NRSub_
+    "PONG" -> Just NRPong_
+    _ -> Nothing
+
+data NtfResponse
+  = NRId NtfEntityId C.PublicKeyX25519
+  | NROk
+  | NRErr ErrorType
+  | NRTkn NtfTknStatus
+  | NRSub NtfSubStatus
+  | NRPong
+  deriving (Show)
+
+instance ProtocolEncoding NtfResponse where
+  type Tag NtfResponse = NtfResponseTag
+  encodeProtocol = \case
+    NRId entId dhKey -> e (NRId_, ' ', entId, dhKey)
+    NROk -> e NROk_
+    NRErr err -> e (NRErr_, ' ', err)
+    NRTkn stat -> e (NRTkn_, ' ', stat)
+    NRSub stat -> e (NRSub_, ' ', stat)
+    NRPong -> e NRPong_
+    where
+      e :: Encoding a => a -> ByteString
+      e = smpEncode
+
+  protocolP = \case
+    NRId_ -> NRId <$> _smpP <*> smpP
+    NROk_ -> pure NROk
+    NRErr_ -> NRErr <$> _smpP
+    NRTkn_ -> NRTkn <$> _smpP
+    NRSub_ -> NRSub <$> _smpP
+    NRPong_ -> pure NRPong
+
+  checkCredentials (_, _, entId, _) cmd = case cmd of
+    -- ID response must not have queue ID
+    NRId {} -> noEntity
+    -- ERR response does not always have entity ID
+    NRErr _ -> Right cmd
+    -- PONG response must not have queue ID
+    NRPong -> noEntity
+    -- other server responses must have entity ID
+    _
+      | B.null entId -> Left $ CMD NO_ENTITY
+      | otherwise -> Right cmd
+    where
+      noEntity
+        | B.null entId = Right cmd
+        | otherwise = Left $ CMD HAS_AUTH
+
+data SMPQueueNtf = SMPQueueNtf
+  { smpServer :: ProtocolServer,
+    notifierId :: NotifierId,
+    notifierKey :: NtfPrivateSignKey
+  }
+  deriving (Show)
+
+instance Encoding SMPQueueNtf where
+  smpEncode SMPQueueNtf {smpServer, notifierId, notifierKey} = smpEncode (smpServer, notifierId, notifierKey)
+  smpP = do
+    (smpServer, notifierId, notifierKey) <- smpP
+    pure $ SMPQueueNtf smpServer notifierId notifierKey
+
+data PushProvider = PPApns
+  deriving (Eq, Ord, Show)
+
+instance Encoding PushProvider where
+  smpEncode = \case
+    PPApns -> "A"
+  smpP =
+    A.anyChar >>= \case
+      'A' -> pure PPApns
+      _ -> fail "bad PushProvider"
+
+instance TextEncoding PushProvider where
+  textEncode = \case
+    PPApns -> "apple"
+  textDecode = \case
+    "apple" -> Just PPApns
+    _ -> Nothing
+
+instance FromField PushProvider where fromField = fromTextField_ textDecode
+
+instance ToField PushProvider where toField = toField . textEncode
+
+data DeviceToken = DeviceToken PushProvider ByteString
+  deriving (Eq, Ord, Show)
+
+instance Encoding DeviceToken where
+  smpEncode (DeviceToken p t) = smpEncode (p, t)
+  smpP = DeviceToken <$> smpP <*> smpP
+
+type NtfEntityId = ByteString
+
+type NtfSubscriptionId = NtfEntityId
+
+type NtfTokenId = NtfEntityId
+
+data NtfSubStatus
+  = -- | state after SNEW
+    NSNew
+  | -- | pending connection/subscription to SMP server
+    NSPending
+  | -- | connected and subscribed to SMP server
+    NSActive
+  | -- | NEND received (we currently do not support it)
+    NSEnd
+  | -- | SMP AUTH error
+    NSSMPAuth
+  deriving (Eq, Show)
+
+instance Encoding NtfSubStatus where
+  smpEncode = \case
+    NSNew -> "NEW"
+    NSPending -> "PENDING" -- e.g. after SMP server disconnect/timeout while ntf server is retrying to connect
+    NSActive -> "ACTIVE"
+    NSEnd -> "END"
+    NSSMPAuth -> "SMP_AUTH"
+  smpP =
+    A.takeTill (== ' ') >>= \case
+      "NEW" -> pure NSNew
+      "PENDING" -> pure NSPending
+      "ACTIVE" -> pure NSActive
+      "END" -> pure NSEnd
+      "SMP_AUTH" -> pure NSSMPAuth
+      _ -> fail "bad NtfSubStatus"
+
+data NtfTknStatus
+  = -- | Token created in DB
+    NTNew
+  | -- | state after registration (TNEW)
+    NTRegistered
+  | -- | if initial notification failed (push provider error) or verification failed
+    NTInvalid
+  | -- | Token confirmed via notification (accepted by push provider or verification code received by client)
+    NTConfirmed
+  | -- | after successful verification (TVFY)
+    NTActive
+  | -- | after it is no longer valid (push provider error)
+    NTExpired
+  deriving (Eq, Show)
+
+instance Encoding NtfTknStatus where
+  smpEncode = \case
+    NTNew -> "NEW"
+    NTRegistered -> "REGISTERED"
+    NTInvalid -> "INVALID"
+    NTConfirmed -> "CONFIRMED"
+    NTActive -> "ACTIVE"
+    NTExpired -> "EXPIRED"
+  smpP =
+    A.takeTill (== ' ') >>= \case
+      "NEW" -> pure NTNew
+      "REGISTERED" -> pure NTRegistered
+      "INVALID" -> pure NTInvalid
+      "CONFIRMED" -> pure NTConfirmed
+      "ACTIVE" -> pure NTActive
+      "EXPIRED" -> pure NTExpired
+      _ -> fail "bad NtfTknStatus"
+
+instance FromField NtfTknStatus where fromField = fromTextField_ $ either (const Nothing) Just . smpDecode . encodeUtf8
+
+instance ToField NtfTknStatus where toField = toField . decodeLatin1 . smpEncode
+
+instance ToJSON NtfTknStatus where
+  toEncoding = JE.text . decodeLatin1 . smpEncode
+  toJSON = J.String . decodeLatin1 . smpEncode
+
+checkEntity :: forall t e e'. (NtfEntityI e, NtfEntityI e') => t e' -> Either String (t e)
+checkEntity c = case testEquality (sNtfEntity @e) (sNtfEntity @e') of
+  Just Refl -> Right c
+  Nothing -> Left "bad command party"
+
+checkEntity' :: forall t p p'. (NtfEntityI p, NtfEntityI p') => t p' -> Maybe (t p)
+checkEntity' c = case testEquality (sNtfEntity @p) (sNtfEntity @p') of
+  Just Refl -> Just c
+  _ -> Nothing

src/Simplex/Messaging/Notifications/Server.hs

@@ -0,0 +1,330 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+
+module Simplex.Messaging.Notifications.Server where
+
+import Control.Logger.Simple
+import Control.Monad.Except
+import Control.Monad.IO.Unlift (MonadUnliftIO)
+import Control.Monad.Reader
+import Crypto.Random (MonadRandom)
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.Text as T
+import Data.Time.Clock.System (getSystemTime)
+import Network.Socket (ServiceName)
+import Simplex.Messaging.Client.Agent
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Notifications.Protocol
+import Simplex.Messaging.Notifications.Server.Env
+import Simplex.Messaging.Notifications.Server.Push.APNS
+import Simplex.Messaging.Notifications.Server.Store
+import Simplex.Messaging.Notifications.Transport
+import Simplex.Messaging.Protocol (ErrorType (..), SignedTransmission, Transmission, encodeTransmission, tGet, tPut)
+import qualified Simplex.Messaging.Protocol as SMP
+import Simplex.Messaging.Server
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Transport (ATransport (..), THandle (..), TProxy, Transport (..))
+import Simplex.Messaging.Transport.Server (runTransportServer)
+import Simplex.Messaging.Util
+import UnliftIO (async, uninterruptibleCancel)
+import UnliftIO.Concurrent (threadDelay)
+import UnliftIO.Exception
+import UnliftIO.STM
+
+runNtfServer :: (MonadRandom m, MonadUnliftIO m) => NtfServerConfig -> m ()
+runNtfServer cfg = do
+  started <- newEmptyTMVarIO
+  runNtfServerBlocking started cfg
+
+runNtfServerBlocking :: (MonadRandom m, MonadUnliftIO m) => TMVar Bool -> NtfServerConfig -> m ()
+runNtfServerBlocking started cfg = runReaderT (ntfServer cfg started) =<< newNtfServerEnv cfg
+
+ntfServer :: forall m. (MonadUnliftIO m, MonadReader NtfEnv m) => NtfServerConfig -> TMVar Bool -> m ()
+ntfServer NtfServerConfig {transports} started = do
+  s <- asks subscriber
+  ps <- asks pushServer
+  raceAny_ (ntfSubscriber s : ntfPush ps : map runServer transports)
+  where
+    runServer :: (ServiceName, ATransport) -> m ()
+    runServer (tcpPort, ATransport t) = do
+      serverParams <- asks tlsServerParams
+      runTransportServer started tcpPort serverParams (runClient t)
+
+    runClient :: Transport c => TProxy c -> c -> m ()
+    runClient _ h = do
+      kh <- asks serverIdentity
+      liftIO (runExceptT $ ntfServerHandshake h kh) >>= \case
+        Right th -> runNtfClientTransport th
+        Left _ -> pure ()
+
+ntfSubscriber :: forall m. MonadUnliftIO m => NtfSubscriber -> m ()
+ntfSubscriber NtfSubscriber {subQ, smpAgent = ca@SMPClientAgent {msgQ, agentQ}} = do
+  raceAny_ [subscribe, receiveSMP, receiveAgent]
+  where
+    subscribe :: m ()
+    subscribe = forever $ do
+      atomically (readTBQueue subQ) >>= \case
+        NtfSub NtfSubData {smpQueue} -> do
+          let SMPQueueNtf {smpServer, notifierId, notifierKey} = smpQueue
+          liftIO (runExceptT $ subscribeQueue ca smpServer ((SPNotifier, notifierId), notifierKey)) >>= \case
+            Right _ -> pure () -- update subscription status
+            Left _e -> pure ()
+
+    receiveSMP :: m ()
+    receiveSMP = forever $ do
+      (_srv, _sessId, _ntfId, msg) <- atomically $ readTBQueue msgQ
+      case msg of
+        SMP.NMSG -> do
+          -- check when the last NMSG was received from this queue
+          -- update timestamp
+          -- check what was the last hidden notification was sent (and whether to this queue)
+          -- decide whether it should be sent as hidden or visible
+          -- construct and possibly encrypt notification
+          -- send it
+          pure ()
+        _ -> pure ()
+      pure ()
+
+    receiveAgent =
+      forever $
+        atomically (readTBQueue agentQ) >>= \case
+          CAConnected _ -> pure ()
+          CADisconnected _srv _subs -> do
+            -- update subscription statuses
+            pure ()
+          CAReconnected _ -> pure ()
+          CAResubscribed _srv _sub -> do
+            -- update subscription status
+            pure ()
+          CASubError _srv _sub _err -> do
+            -- update subscription status
+            pure ()
+
+ntfPush :: MonadUnliftIO m => NtfPushServer -> m ()
+ntfPush s@NtfPushServer {pushQ} = liftIO . forever . runExceptT $ do
+  (tkn@NtfTknData {token = DeviceToken pp _, tknStatus}, ntf) <- atomically (readTBQueue pushQ)
+  logDebug $ "sending push notification to " <> T.pack (show pp)
+  status <- readTVarIO tknStatus
+  case (status, ntf) of
+    (_, PNVerification _) -> do
+      -- TODO check token status
+      deliverNotification pp tkn ntf
+      atomically $ modifyTVar tknStatus $ \status' -> if status' == NTActive then NTActive else NTConfirmed
+    (NTActive, PNCheckMessages) -> do
+      deliverNotification pp tkn ntf
+    _ -> do
+      logError "bad notification token status"
+  where
+    deliverNotification :: PushProvider -> PushProviderClient
+    deliverNotification pp tkn ntf = do
+      deliver <- liftIO $ getPushClient s pp
+      -- TODO retry later based on the error
+      deliver tkn ntf `catchError` \e -> logError (T.pack $ "Push provider error (" <> show pp <> "): " <> show e) >> throwError e
+
+runNtfClientTransport :: (Transport c, MonadUnliftIO m, MonadReader NtfEnv m) => THandle c -> m ()
+runNtfClientTransport th@THandle {sessionId} = do
+  qSize <- asks $ clientQSize . config
+  ts <- liftIO getSystemTime
+  c <- atomically $ newNtfServerClient qSize sessionId ts
+  s <- asks subscriber
+  ps <- asks pushServer
+  expCfg <- asks $ inactiveClientExpiration . config
+  raceAny_ ([send th c, client c s ps, receive th c] <> disconnectThread_ c expCfg)
+    `finally` clientDisconnected c
+  where
+    disconnectThread_ c expCfg = maybe [] ((: []) . disconnectTransport th c activeAt) expCfg
+
+clientDisconnected :: MonadUnliftIO m => NtfServerClient -> m ()
+clientDisconnected NtfServerClient {connected} = atomically $ writeTVar connected False
+
+receive :: (Transport c, MonadUnliftIO m, MonadReader NtfEnv m) => THandle c -> NtfServerClient -> m ()
+receive th NtfServerClient {rcvQ, sndQ, activeAt} = forever $ do
+  t@(_, _, (corrId, entId, cmdOrError)) <- tGet th
+  atomically . writeTVar activeAt =<< liftIO getSystemTime
+  logDebug "received transmission"
+  case cmdOrError of
+    Left e -> write sndQ (corrId, entId, NRErr e)
+    Right cmd ->
+      verifyNtfTransmission t cmd >>= \case
+        VRVerified req -> write rcvQ req
+        VRFailed -> write sndQ (corrId, entId, NRErr AUTH)
+  where
+    write q t = atomically $ writeTBQueue q t
+
+send :: (Transport c, MonadUnliftIO m) => THandle c -> NtfServerClient -> m ()
+send h NtfServerClient {sndQ, sessionId, activeAt} = forever $ do
+  t <- atomically $ readTBQueue sndQ
+  void . liftIO $ tPut h (Nothing, encodeTransmission sessionId t)
+  atomically . writeTVar activeAt =<< liftIO getSystemTime
+
+data VerificationResult = VRVerified NtfRequest | VRFailed
+
+verifyNtfTransmission ::
+  forall m. (MonadUnliftIO m, MonadReader NtfEnv m) => SignedTransmission NtfCmd -> NtfCmd -> m VerificationResult
+verifyNtfTransmission (sig_, signed, (corrId, entId, _)) cmd = do
+  st <- asks store
+  case cmd of
+    NtfCmd SToken c@(TNEW tkn@(NewNtfTkn _ k _)) -> do
+      r_ <- atomically $ getNtfTokenRegistration st tkn
+      pure $
+        if verifyCmdSignature sig_ signed k
+          then case r_ of
+            Just t@NtfTknData {tknVerifyKey}
+              | k == tknVerifyKey -> verifiedTknCmd t c
+              | otherwise -> VRFailed
+            _ -> VRVerified (NtfReqNew corrId (ANE SToken tkn))
+          else VRFailed
+    NtfCmd SToken c -> do
+      t_ <- atomically $ getNtfToken st entId
+      pure $ case t_ of
+        Just t@NtfTknData {tknVerifyKey}
+          | verifyCmdSignature sig_ signed tknVerifyKey -> verifiedTknCmd t c
+          | otherwise -> VRFailed
+        _ -> maybe False (dummyVerifyCmd signed) sig_ `seq` VRFailed
+    _ -> pure VRFailed
+  where
+    verifiedTknCmd t c = VRVerified (NtfReqCmd SToken (NtfTkn t) (corrId, entId, c))
+
+client :: forall m. (MonadUnliftIO m, MonadReader NtfEnv m) => NtfServerClient -> NtfSubscriber -> NtfPushServer -> m ()
+client NtfServerClient {rcvQ, sndQ} NtfSubscriber {subQ = _} NtfPushServer {pushQ, intervalNotifiers} =
+  forever $
+    atomically (readTBQueue rcvQ)
+      >>= processCommand
+      >>= atomically . writeTBQueue sndQ
+  where
+    processCommand :: NtfRequest -> m (Transmission NtfResponse)
+    processCommand = \case
+      NtfReqNew corrId (ANE SToken newTkn@(NewNtfTkn _ _ dhPubKey)) -> do
+        logDebug "TNEW - new token"
+        st <- asks store
+        ks@(srvDhPubKey, srvDhPrivKey) <- liftIO C.generateKeyPair'
+        let dhSecret = C.dh' dhPubKey srvDhPrivKey
+        tknId <- getId
+        regCode <- getRegCode
+        atomically $ do
+          tkn <- mkNtfTknData tknId newTkn ks dhSecret regCode
+          addNtfToken st tknId tkn
+          writeTBQueue pushQ (tkn, PNVerification regCode)
+        pure (corrId, "", NRId tknId srvDhPubKey)
+      NtfReqCmd SToken (NtfTkn tkn@NtfTknData {ntfTknId, tknStatus, tknRegCode, tknDhSecret, tknDhKeys = (srvDhPubKey, srvDhPrivKey)}) (corrId, tknId, cmd) -> do
+        status <- readTVarIO tknStatus
+        (corrId,tknId,) <$> case cmd of
+          TNEW (NewNtfTkn _ _ dhPubKey) -> do
+            logDebug "TNEW - registered token"
+            let dhSecret = C.dh' dhPubKey srvDhPrivKey
+            -- it is required that DH secret is the same, to avoid failed verifications if notification is delaying
+            if tknDhSecret == dhSecret
+              then do
+                atomically $ writeTBQueue pushQ (tkn, PNVerification tknRegCode)
+                pure $ NRId ntfTknId srvDhPubKey
+              else pure $ NRErr AUTH
+          TVFY code -- this allows repeated verification for cases when client connection dropped before server response
+            | (status == NTRegistered || status == NTConfirmed || status == NTActive) && tknRegCode == code -> do
+              logDebug "TVFY - token verified"
+              st <- asks store
+              atomically $ writeTVar tknStatus NTActive
+              tIds <- atomically $ removeInactiveTokenRegistrations st tkn
+              forM_ tIds cancelInvervalNotifications
+              pure NROk
+            | otherwise -> do
+              logDebug "TVFY - incorrect code or token status"
+              pure $ NRErr AUTH
+          TCHK -> pure $ NRTkn status
+          TDEL -> do
+            logDebug "TDEL"
+            st <- asks store
+            atomically $ deleteNtfToken st tknId
+            cancelInvervalNotifications tknId
+            pure NROk
+          TCRN 0 -> do
+            logDebug "TCRN 0"
+            cancelInvervalNotifications tknId
+            pure NROk
+          TCRN int
+            | int < 20 -> pure $ NRErr QUOTA
+            | otherwise -> do
+              logDebug "TCRN"
+              atomically (TM.lookup tknId intervalNotifiers) >>= \case
+                Nothing -> runIntervalNotifier int
+                Just IntervalNotifier {interval, action} ->
+                  unless (interval == int) $ do
+                    uninterruptibleCancel action
+                    runIntervalNotifier int
+              pure NROk
+            where
+              runIntervalNotifier interval = do
+                action <- async . intervalNotifier $ fromIntegral interval * 1000000 * 60
+                let notifier = IntervalNotifier {action, token = tkn, interval}
+                atomically $ TM.insert tknId notifier intervalNotifiers
+                where
+                  intervalNotifier delay = forever $ do
+                    threadDelay delay
+                    atomically $ writeTBQueue pushQ (tkn, PNCheckMessages)
+      NtfReqNew corrId (ANE SSubscription _newSub) -> pure (corrId, "", NROk)
+      NtfReqCmd SSubscription _sub (corrId, subId, cmd) ->
+        (corrId,subId,) <$> case cmd of
+          SNEW _newSub -> pure NROk
+          SCHK -> pure NROk
+          SDEL -> pure NROk
+          PING -> pure NRPong
+    getId :: m NtfEntityId
+    getId = getRandomBytes =<< asks (subIdBytes . config)
+    getRegCode :: m NtfRegCode
+    getRegCode = NtfRegCode <$> (getRandomBytes =<< asks (regCodeBytes . config))
+    getRandomBytes :: Int -> m ByteString
+    getRandomBytes n = do
+      gVar <- asks idsDrg
+      atomically (C.pseudoRandomBytes n gVar)
+    cancelInvervalNotifications :: NtfTokenId -> m ()
+    cancelInvervalNotifications tknId =
+      atomically (TM.lookupDelete tknId intervalNotifiers)
+        >>= mapM_ (uninterruptibleCancel . action)
+
+-- NReqCreate corrId tokenId smpQueue -> pure (corrId, "", NROk)
+-- do
+-- st <- asks store
+-- (pubDhKey, privDhKey) <- liftIO C.generateKeyPair'
+-- let dhSecret = C.dh' dhPubKey privDhKey
+-- sub <- atomically $ mkNtfSubsciption smpQueue token verifyKey dhSecret
+-- addSubRetry 3 st sub >>= \case
+--   Nothing -> pure (corrId, "", NRErr INTERNAL)
+--   Just sId -> do
+--     atomically $ writeTBQueue subQ sub
+--     pure (corrId, sId, NRSubId pubDhKey)
+-- where
+--   addSubRetry :: Int -> NtfSubscriptionsStore -> NtfSubsciption -> m (Maybe NtfSubsciptionId)
+--   addSubRetry 0 _ _ = pure Nothing
+--   addSubRetry n st sub = do
+--     sId <- getId
+--     -- create QueueRec record with these ids and keys
+--     atomically (addNtfSub st sId sub) >>= \case
+--       Nothing -> addSubRetry (n - 1) st sub
+--       _ -> pure $ Just sId
+--   getId :: m NtfSubsciptionId
+--   getId = do
+--     n <- asks $ subIdBytes . config
+--     gVar <- asks idsDrg
+--     atomically (randomBytes n gVar)
+-- NReqCommand sub@NtfSubsciption {tokenId, subStatus} (corrId, subId, cmd) ->
+--   (corrId,subId,) <$> case cmd of
+--     NCSubCreate tokenId smpQueue -> pure NROk
+-- do
+--   st <- asks store
+--   (pubDhKey, privDhKey) <- liftIO C.generateKeyPair'
+--   let dhSecret = C.dh' (dhPubKey newSub) privDhKey
+--   atomically (updateNtfSub st sub newSub dhSecret) >>= \case
+--     Nothing -> pure $ NRErr INTERNAL
+--     _ -> atomically $ do
+--       whenM ((== NSEnd) <$> readTVar status) $ writeTBQueue subQ sub
+--       pure $ NRSubId pubDhKey
+-- NCSubCheck -> NRStat <$> readTVarIO subStatus
+-- NCSubDelete -> do
+--   st <- asks store
+--   atomically (deleteNtfSub st subId) $> NROk

src/Simplex/Messaging/Notifications/Server/Env.hs

@@ -0,0 +1,140 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+
+module Simplex.Messaging.Notifications.Server.Env where
+
+import Control.Concurrent.Async (Async)
+import Control.Monad (void)
+import Control.Monad.IO.Unlift
+import Crypto.Random
+import Data.ByteString.Char8 (ByteString)
+import Data.Time.Clock.System (SystemTime)
+import Data.Word (Word16)
+import Data.X509.Validation (Fingerprint (..))
+import Network.Socket
+import qualified Network.TLS as T
+import Numeric.Natural
+import Simplex.Messaging.Client.Agent
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Notifications.Protocol
+import Simplex.Messaging.Notifications.Server.Push.APNS
+import Simplex.Messaging.Notifications.Server.Store
+import Simplex.Messaging.Protocol (CorrId, Transmission)
+import Simplex.Messaging.Server.Expiration
+import Simplex.Messaging.TMap (TMap)
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Transport (ATransport)
+import Simplex.Messaging.Transport.Server (loadFingerprint, loadTLSServerParams)
+import UnliftIO.STM
+
+data NtfServerConfig = NtfServerConfig
+  { transports :: [(ServiceName, ATransport)],
+    subIdBytes :: Int,
+    regCodeBytes :: Int,
+    clientQSize :: Natural,
+    subQSize :: Natural,
+    pushQSize :: Natural,
+    smpAgentCfg :: SMPClientAgentConfig,
+    apnsConfig :: APNSPushClientConfig,
+    inactiveClientExpiration :: Maybe ExpirationConfig,
+    -- CA certificate private key is not needed for initialization
+    caCertificateFile :: FilePath,
+    privateKeyFile :: FilePath,
+    certificateFile :: FilePath
+  }
+
+defaultInactiveClientExpiration :: ExpirationConfig
+defaultInactiveClientExpiration =
+  ExpirationConfig
+    { ttl = 7200, -- 2 hours
+      checkInterval = 3600 -- seconds, 1 hour
+    }
+
+data NtfEnv = NtfEnv
+  { config :: NtfServerConfig,
+    subscriber :: NtfSubscriber,
+    pushServer :: NtfPushServer,
+    store :: NtfStore,
+    idsDrg :: TVar ChaChaDRG,
+    serverIdentity :: C.KeyHash,
+    tlsServerParams :: T.ServerParams,
+    serverIdentity :: C.KeyHash
+  }
+
+newNtfServerEnv :: (MonadUnliftIO m, MonadRandom m) => NtfServerConfig -> m NtfEnv
+newNtfServerEnv config@NtfServerConfig {subQSize, pushQSize, smpAgentCfg, apnsConfig, caCertificateFile, certificateFile, privateKeyFile} = do
+  idsDrg <- newTVarIO =<< drgNew
+  store <- atomically newNtfStore
+  subscriber <- atomically $ newNtfSubscriber subQSize smpAgentCfg
+  pushServer <- atomically $ newNtfPushServer pushQSize apnsConfig
+  -- TODO not creating APNS client on start to pass CI test, has to be replaced with mock APNS server
+  void . liftIO $ newPushClient pushServer PPApns
+  tlsServerParams <- liftIO $ loadTLSServerParams caCertificateFile certificateFile privateKeyFile
+  Fingerprint fp <- liftIO $ loadFingerprint caCertificateFile
+  pure NtfEnv {config, subscriber, pushServer, store, idsDrg, tlsServerParams, serverIdentity = C.KeyHash fp}
+
+data NtfSubscriber = NtfSubscriber
+  { subQ :: TBQueue (NtfEntityRec 'Subscription),
+    smpAgent :: SMPClientAgent
+  }
+
+newNtfSubscriber :: Natural -> SMPClientAgentConfig -> STM NtfSubscriber
+newNtfSubscriber qSize smpAgentCfg = do
+  smpAgent <- newSMPClientAgent smpAgentCfg
+  subQ <- newTBQueue qSize
+  pure NtfSubscriber {smpAgent, subQ}
+
+data NtfPushServer = NtfPushServer
+  { pushQ :: TBQueue (NtfTknData, PushNotification),
+    pushClients :: TMap PushProvider PushProviderClient,
+    intervalNotifiers :: TMap NtfTokenId IntervalNotifier,
+    apnsConfig :: APNSPushClientConfig
+  }
+
+data IntervalNotifier = IntervalNotifier
+  { action :: Async (),
+    token :: NtfTknData,
+    interval :: Word16
+  }
+
+newNtfPushServer :: Natural -> APNSPushClientConfig -> STM NtfPushServer
+newNtfPushServer qSize apnsConfig = do
+  pushQ <- newTBQueue qSize
+  pushClients <- TM.empty
+  intervalNotifiers <- TM.empty
+  pure NtfPushServer {pushQ, pushClients, intervalNotifiers, apnsConfig}
+
+newPushClient :: NtfPushServer -> PushProvider -> IO PushProviderClient
+newPushClient NtfPushServer {apnsConfig, pushClients} = \case
+  PPApns -> do
+    c <- apnsPushProviderClient <$> createAPNSPushClient apnsConfig
+    atomically $ TM.insert PPApns c pushClients
+    pure c
+
+getPushClient :: NtfPushServer -> PushProvider -> IO PushProviderClient
+getPushClient s@NtfPushServer {pushClients} pp =
+  atomically (TM.lookup pp pushClients) >>= maybe (newPushClient s pp) pure
+
+data NtfRequest
+  = NtfReqNew CorrId ANewNtfEntity
+  | forall e. NtfEntityI e => NtfReqCmd (SNtfEntity e) (NtfEntityRec e) (Transmission (NtfCommand e))
+
+data NtfServerClient = NtfServerClient
+  { rcvQ :: TBQueue NtfRequest,
+    sndQ :: TBQueue (Transmission NtfResponse),
+    sessionId :: ByteString,
+    connected :: TVar Bool,
+    activeAt :: TVar SystemTime
+  }
+
+newNtfServerClient :: Natural -> ByteString -> SystemTime -> STM NtfServerClient
+newNtfServerClient qSize sessionId ts = do
+  rcvQ <- newTBQueue qSize
+  sndQ <- newTBQueue qSize
+  connected <- newTVar True
+  activeAt <- newTVar ts
+  return NtfServerClient {rcvQ, sndQ, sessionId, connected, activeAt}

src/Simplex/Messaging/Notifications/Server/Push/.gitignore

@@ -0,0 +1 @@
+local.env

src/Simplex/Messaging/Notifications/Server/Push/APNS.hs

@@ -0,0 +1,349 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
+
+{-# HLINT ignore "Use newtype instead of data" #-}
+
+module Simplex.Messaging.Notifications.Server.Push.APNS where
+
+import Control.Logger.Simple
+import Control.Monad.Except
+import Crypto.Hash.Algorithms (SHA256 (..))
+import qualified Crypto.PubKey.ECC.ECDSA as EC
+import qualified Crypto.PubKey.ECC.Types as ECT
+import Crypto.Random (ChaChaDRG, drgNew)
+import qualified Crypto.Store.PKCS8 as PK
+import Data.ASN1.BinaryEncoding (DER (..))
+import Data.ASN1.Encoding
+import Data.ASN1.Types
+import Data.Aeson (FromJSON, ToJSON, (.=))
+import qualified Data.Aeson as J
+import qualified Data.Aeson.Encoding as JE
+import Data.Bifunctor (first)
+import qualified Data.ByteString.Base64.URL as U
+import Data.ByteString.Builder (lazyByteString)
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Lazy.Char8 as LB
+import qualified Data.CaseInsensitive as CI
+import Data.Int (Int64)
+import Data.Map.Strict (Map)
+import Data.Text (Text)
+import qualified Data.Text as T
+import Data.Text.Encoding (decodeUtf8With)
+import Data.Time.Clock.System
+import qualified Data.X509 as X
+import GHC.Generics (Generic)
+import Network.HTTP.Types (HeaderName, Status)
+import qualified Network.HTTP.Types as N
+import Network.HTTP2.Client (Request)
+import qualified Network.HTTP2.Client as H
+import Network.Socket (HostName, ServiceName)
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Notifications.Protocol
+import Simplex.Messaging.Notifications.Server.Store (NtfTknData (..))
+import Simplex.Messaging.Protocol (NotifierId, SMPServer)
+import Simplex.Messaging.Transport.HTTP2.Client
+import System.Environment (getEnv)
+import UnliftIO.STM
+
+data JWTHeader = JWTHeader
+  { alg :: Text, -- key algorithm, ES256 for APNS
+    kid :: Text -- key ID
+  }
+  deriving (Show, Generic)
+
+instance ToJSON JWTHeader where toEncoding = J.genericToEncoding J.defaultOptions
+
+data JWTClaims = JWTClaims
+  { iss :: Text, -- issuer, team ID for APNS
+    iat :: Int64 -- issue time, seconds from epoch
+  }
+  deriving (Show, Generic)
+
+instance ToJSON JWTClaims where toEncoding = J.genericToEncoding J.defaultOptions
+
+data JWTToken = JWTToken JWTHeader JWTClaims
+  deriving (Show)
+
+mkJWTToken :: JWTHeader -> Text -> IO JWTToken
+mkJWTToken hdr iss = do
+  iat <- systemSeconds <$> getSystemTime
+  pure $ JWTToken hdr JWTClaims {iss, iat}
+
+type SignedJWTToken = ByteString
+
+signedJWTToken :: EC.PrivateKey -> JWTToken -> IO SignedJWTToken
+signedJWTToken pk (JWTToken hdr claims) = do
+  let hc = jwtEncode hdr <> "." <> jwtEncode claims
+  sig <- EC.sign pk SHA256 hc
+  pure $ hc <> "." <> serialize sig
+  where
+    jwtEncode :: ToJSON a => a -> ByteString
+    jwtEncode = U.encodeUnpadded . LB.toStrict . J.encode
+    serialize sig = U.encodeUnpadded $ encodeASN1' DER [Start Sequence, IntVal (EC.sign_r sig), IntVal (EC.sign_s sig), End Sequence]
+
+readECPrivateKey :: FilePath -> IO EC.PrivateKey
+readECPrivateKey f = do
+  -- TODO this is specific to APNS key
+  [PK.Unprotected (X.PrivKeyEC X.PrivKeyEC_Named {privkeyEC_name, privkeyEC_priv})] <- PK.readKeyFile f
+  pure EC.PrivateKey {private_curve = ECT.getCurveByName privkeyEC_name, private_d = privkeyEC_priv}
+
+data PushNotification
+  = PNVerification NtfRegCode
+  | PNMessage SMPServer NotifierId
+  | PNAlert Text
+  | PNCheckMessages
+
+data APNSNotification = APNSNotification {aps :: APNSNotificationBody, notificationData :: Maybe J.Value}
+  deriving (Show, Generic)
+
+instance ToJSON APNSNotification where
+  toJSON = J.genericToJSON J.defaultOptions {J.omitNothingFields = True}
+  toEncoding = J.genericToEncoding J.defaultOptions {J.omitNothingFields = True}
+
+data APNSNotificationBody
+  = APNSAlert {alert :: APNSAlertBody, badge :: Maybe Int, sound :: Maybe Text, category :: Maybe Text}
+  | APNSBackground {contentAvailable :: Int}
+  | APNSMutableContent {mutableContent :: Int, alert :: APNSAlertBody, category :: Maybe Text}
+  deriving (Show, Generic)
+
+apnsJSONOptions :: J.Options
+apnsJSONOptions = J.defaultOptions {J.omitNothingFields = True, J.sumEncoding = J.UntaggedValue, J.fieldLabelModifier = J.camelTo2 '-'}
+
+instance ToJSON APNSNotificationBody where
+  toJSON = J.genericToJSON apnsJSONOptions
+  toEncoding = J.genericToEncoding apnsJSONOptions
+
+type APNSNotificationData = Map Text Text
+
+data APNSAlertBody = APNSAlertObject {title :: Text, subtitle :: Text, body :: Text} | APNSAlertText Text
+  deriving (Show)
+
+instance ToJSON APNSAlertBody where
+  toEncoding = \case
+    APNSAlertObject {title, subtitle, body} -> J.pairs $ "title" .= title <> "subtitle" .= subtitle <> "body" .= body
+    APNSAlertText t -> JE.text t
+  toJSON = \case
+    APNSAlertObject {title, subtitle, body} -> J.object ["title" .= title, "subtitle" .= subtitle, "body" .= body]
+    APNSAlertText t -> J.String t
+
+-- APNS notification types
+--
+-- Visible alerts:
+-- {
+--    "aps" : {
+--       "alert" : {
+--          "title" : "Game Request",
+--          "subtitle" : "Five Card Draw",
+--          "body" : "Bob wants to play poker"
+--       },
+--       "badge" : 9,
+--       "sound" : "bingbong.aiff",
+--       "category" : "GAME_INVITATION"
+--    },
+--    "gameID" : "12345678"
+-- }
+--
+-- Simple text alert:
+-- {"aps":{"alert":"you have a new message"}}
+--
+-- Background notification to fetch content
+-- {"aps":{"content-available":1}}
+--
+-- Mutable content notification that must be shown but can be processed before before being shown (up to 30 sec)
+-- {
+--    "aps" : {
+--       "category" : "SECRET",
+--       "mutable-content" : 1,
+--       "alert" : {
+--          "title" : "Secret Message!",
+--          "body"  : "(Encrypted)"
+--      },
+--    },
+--    "ENCRYPTED_DATA" : "Salted__·öîQÊ$UDì_¶Ù∞èΩ^¬%gq∞NÿÒQùw"
+-- }
+
+data APNSPushClientConfig = APNSPushClientConfig
+  { tokenTTL :: Int64,
+    authKeyFileEnv :: String,
+    authKeyAlg :: Text,
+    authKeyIdEnv :: String,
+    paddedNtfLength :: Int,
+    appName :: ByteString,
+    appTeamId :: Text,
+    apnsHost :: HostName,
+    apnsPort :: ServiceName,
+    http2cfg :: HTTP2ClientConfig
+  }
+  deriving (Show)
+
+defaultAPNSPushClientConfig :: APNSPushClientConfig
+defaultAPNSPushClientConfig =
+  APNSPushClientConfig
+    { tokenTTL = 1200, -- 20 minutes
+      authKeyFileEnv = "APNS_KEY_FILE", -- the environment variables APNS_KEY_FILE and APNS_KEY_ID must be set, or the server would fail to start
+      authKeyAlg = "ES256",
+      authKeyIdEnv = "APNS_KEY_ID",
+      paddedNtfLength = 256,
+      appName = "chat.simplex.app",
+      appTeamId = "5NN7GUYB6T",
+      apnsHost = "api.sandbox.push.apple.com",
+      apnsPort = "443",
+      http2cfg = defaultHTTP2ClientConfig
+    }
+
+data APNSPushClient = APNSPushClient
+  { https2Client :: TVar (Maybe HTTP2Client),
+    privateKey :: EC.PrivateKey,
+    jwtHeader :: JWTHeader,
+    jwtToken :: TVar (JWTToken, SignedJWTToken),
+    nonceDrg :: TVar ChaChaDRG,
+    apnsCfg :: APNSPushClientConfig
+  }
+
+createAPNSPushClient :: APNSPushClientConfig -> IO APNSPushClient
+createAPNSPushClient apnsCfg@APNSPushClientConfig {authKeyFileEnv, authKeyAlg, authKeyIdEnv, appTeamId} = do
+  https2Client <- newTVarIO Nothing
+  void $ connectHTTPS2 apnsCfg https2Client
+  privateKey <- readECPrivateKey =<< getEnv authKeyFileEnv
+  authKeyId <- T.pack <$> getEnv authKeyIdEnv
+  let jwtHeader = JWTHeader {alg = authKeyAlg, kid = authKeyId}
+  jwtToken <- newTVarIO =<< mkApnsJWTToken appTeamId jwtHeader privateKey
+  nonceDrg <- drgNew >>= newTVarIO
+  pure APNSPushClient {https2Client, privateKey, jwtHeader, jwtToken, nonceDrg, apnsCfg}
+
+getApnsJWTToken :: APNSPushClient -> IO SignedJWTToken
+getApnsJWTToken APNSPushClient {apnsCfg = APNSPushClientConfig {appTeamId, tokenTTL}, privateKey, jwtHeader, jwtToken} = do
+  (jwt, signedJWT) <- readTVarIO jwtToken
+  age <- jwtTokenAge jwt
+  if age < tokenTTL
+    then pure signedJWT
+    else do
+      t@(_, signedJWT') <- mkApnsJWTToken appTeamId jwtHeader privateKey
+      atomically $ writeTVar jwtToken t
+      pure signedJWT'
+  where
+    jwtTokenAge (JWTToken _ JWTClaims {iat}) = subtract iat . systemSeconds <$> getSystemTime
+
+mkApnsJWTToken :: Text -> JWTHeader -> EC.PrivateKey -> IO (JWTToken, SignedJWTToken)
+mkApnsJWTToken appTeamId jwtHeader privateKey = do
+  jwt <- mkJWTToken jwtHeader appTeamId
+  signedJWT <- signedJWTToken privateKey jwt
+  pure (jwt, signedJWT)
+
+connectHTTPS2 :: APNSPushClientConfig -> TVar (Maybe HTTP2Client) -> IO (Either HTTP2ClientError HTTP2Client)
+connectHTTPS2 APNSPushClientConfig {apnsHost, apnsPort, http2cfg} https2Client = do
+  r <- getHTTP2Client apnsHost apnsPort http2cfg disconnected
+  case r of
+    Right client -> atomically . writeTVar https2Client $ Just client
+    Left e -> putStrLn $ "Error connecting to APNS: " <> show e
+  pure r
+  where
+    disconnected = atomically $ writeTVar https2Client Nothing
+
+getApnsHTTP2Client :: APNSPushClient -> IO (Either HTTP2ClientError HTTP2Client)
+getApnsHTTP2Client APNSPushClient {https2Client, apnsCfg} =
+  readTVarIO https2Client >>= maybe (connectHTTPS2 apnsCfg https2Client) (pure . Right)
+
+disconnectApnsHTTP2Client :: APNSPushClient -> IO ()
+disconnectApnsHTTP2Client APNSPushClient {https2Client} =
+  readTVarIO https2Client >>= mapM_ closeHTTP2Client >> atomically (writeTVar https2Client Nothing)
+
+apnsNotification :: NtfTknData -> C.CbNonce -> Int -> PushNotification -> Either C.CryptoError APNSNotification
+apnsNotification NtfTknData {tknDhSecret} nonce paddedLen = \case
+  PNVerification (NtfRegCode code) ->
+    encrypt code $ \code' ->
+      apn APNSBackground {contentAvailable = 1} . Just $ J.object ["verification" .= code', "nonce" .= nonce]
+  PNMessage srv nId ->
+    encrypt (strEncode srv <> "/" <> strEncode nId) $ \ntfQueue ->
+      apn apnMutableContent . Just $ J.object ["checkMessage" .= ntfQueue, "nonce" .= nonce]
+  PNAlert text -> Right $ apn (apnAlert $ APNSAlertText text) Nothing
+  PNCheckMessages -> Right $ apn APNSBackground {contentAvailable = 1} . Just $ J.object ["checkMessages" .= True]
+  where
+    encrypt :: ByteString -> (Text -> APNSNotification) -> Either C.CryptoError APNSNotification
+    encrypt ntfData f = f . safeDecodeUtf8 . U.encode <$> C.cbEncrypt tknDhSecret nonce ntfData paddedLen
+    apn aps notificationData = APNSNotification {aps, notificationData}
+    apnMutableContent = APNSMutableContent {mutableContent = 1, alert = APNSAlertText "Encrypted message or some other app event", category = Nothing}
+    apnAlert alert = APNSAlert {alert, badge = Nothing, sound = Nothing, category = Nothing}
+    safeDecodeUtf8 = decodeUtf8With onError where onError _ _ = Just '?'
+
+apnsRequest :: APNSPushClient -> ByteString -> APNSNotification -> IO Request
+apnsRequest c tkn ntf@APNSNotification {aps} = do
+  signedJWT <- getApnsJWTToken c
+  pure $ H.requestBuilder N.methodPost path (headers signedJWT) (lazyByteString $ J.encode ntf)
+  where
+    path = "/3/device/" <> tkn
+    headers signedJWT =
+      [ (hApnsTopic, appName $ apnsCfg (c :: APNSPushClient)),
+        (hApnsPushType, pushType aps),
+        (N.hAuthorization, "bearer " <> signedJWT)
+      ]
+        <> [(hApnsPriority, "5") | isBackground aps]
+    isBackground = \case
+      APNSBackground {} -> True
+      _ -> False
+    pushType = \case
+      APNSBackground {} -> "background"
+      _ -> "alert"
+
+data PushProviderError
+  = PPConnection HTTP2ClientError
+  | PPCryptoError C.CryptoError
+  | PPResponseError (Maybe Status) Text
+  | PPTokenInvalid
+  | PPRetryLater
+  | PPPermanentError
+  deriving (Show)
+
+type PushProviderClient = NtfTknData -> PushNotification -> ExceptT PushProviderError IO ()
+
+-- this is not a newtype on purpose to have a correct JSON encoding as a record
+data APNSErrorResponse = APNSErrorResponse {reason :: Text}
+  deriving (Generic, FromJSON)
+
+apnsPushProviderClient :: APNSPushClient -> PushProviderClient
+apnsPushProviderClient c@APNSPushClient {nonceDrg, apnsCfg} tkn@NtfTknData {token = DeviceToken PPApns tknStr} pn = do
+  http2 <- liftHTTPS2 $ getApnsHTTP2Client c
+  nonce <- atomically $ C.pseudoRandomCbNonce nonceDrg
+  apnsNtf <- liftEither $ first PPCryptoError $ apnsNotification tkn nonce (paddedNtfLength apnsCfg) pn
+  req <- liftIO $ apnsRequest c tknStr apnsNtf
+  HTTP2Response {response, respBody} <- liftHTTPS2 $ sendRequest http2 req
+  let status = H.responseStatus response
+      reason' = maybe "" reason $ J.decodeStrict' respBody
+  logDebug $ "APNS response: " <> T.pack (show status) <> " " <> reason'
+  result status reason'
+  where
+    result :: Maybe Status -> Text -> ExceptT PushProviderError IO ()
+    result status reason'
+      | status == Just N.ok200 = pure ()
+      | status == Just N.badRequest400 =
+        case reason' of
+          "BadDeviceToken" -> throwError PPTokenInvalid
+          "DeviceTokenNotForTopic" -> throwError PPTokenInvalid
+          "TopicDisallowed" -> throwError PPPermanentError
+          _ -> err status reason'
+      | status == Just N.forbidden403 = case reason' of
+        "ExpiredProviderToken" -> throwError PPPermanentError -- there should be no point retrying it as the token was refreshed
+        "InvalidProviderToken" -> throwError PPPermanentError
+        _ -> err status reason'
+      | status == Just N.gone410 = throwError PPTokenInvalid
+      | status == Just N.serviceUnavailable503 = liftIO (disconnectApnsHTTP2Client c) >> throwError PPRetryLater
+      -- Just tooManyRequests429 -> TODO TooManyRequests - too many requests for the same token
+      | otherwise = err status reason'
+    err :: Maybe Status -> Text -> ExceptT PushProviderError IO ()
+    err s r = throwError $ PPResponseError s r
+    liftHTTPS2 a = ExceptT $ first PPConnection <$> a
+
+hApnsTopic :: HeaderName
+hApnsTopic = CI.mk "apns-topic"
+
+hApnsPushType :: HeaderName
+hApnsPushType = CI.mk "apns-push-type"
+
+hApnsPriority :: HeaderName
+hApnsPriority = CI.mk "apns-priority"

src/Simplex/Messaging/Notifications/Server/Push/testpush.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+export TEAM_ID=5NN7GUYB6T
+# export APNS_KEY_FILE=""
+# export APNS_KEY_ID=""
+export TOPIC=chat.simplex.app
+# export DEVICE_TOKEN=
+export APNS_HOST_NAME=api.sandbox.push.apple.com
+
+export JWT_ISSUE_TIME=$(date +%s)
+export JWT_HEADER=$(printf '{"alg":"ES256","kid":"%s"}' "${APNS_KEY_ID}" | openssl base64 -e -A | tr -- '+/' '-_' | tr -d =)
+export JWT_CLAIMS=$(printf '{"iss":"%s","iat":%d}' "${TEAM_ID}" "${JWT_ISSUE_TIME}" | openssl base64 -e -A | tr -- '+/' '-_' | tr -d =)
+export JWT_HEADER_CLAIMS="${JWT_HEADER}.${JWT_CLAIMS}"
+
+export JWT_SIGNED_HEADER_CLAIMS=$(printf "${JWT_HEADER_CLAIMS}" | openssl dgst -binary -sha256 -sign "${APNS_KEY_FILE}" | openssl base64 -e -A | tr -- '+/' '-_' | tr -d =)
+export AUTHENTICATION_TOKEN="${JWT_HEADER}.${JWT_CLAIMS}.${JWT_SIGNED_HEADER_CLAIMS}"
+
+# simple alert
+# curl -v --header "apns-topic: $TOPIC" --header "apns-push-type: alert" --header "authorization: bearer $AUTHENTICATION_TOKEN" --data '{"aps":{"alert":"you have a new message"},"data":{"test":"123"}}' --http2 https://${APNS_HOST_NAME}/3/device/${DEVICE_TOKEN}
+
+# background notification
+# curl -v --header "apns-topic: $TOPIC" --header "apns-push-type: background" --header "apns-priority: 5" --header "authorization: bearer $AUTHENTICATION_TOKEN" --data '{"aps":{"content-available":1}}' --http2 https://${APNS_HOST_NAME}/3/device/${DEVICE_TOKEN}
+
+# mutable-content notification
+# NTF_CAT_CHECK_MESSAGE category will not show alert if the app is in foreground
+curl -v --header "apns-topic: $TOPIC" --header "apns-push-type: alert" --header "authorization: bearer $AUTHENTICATION_TOKEN" --data '{"aps":{"category": "NTF_CAT_CHECK_MESSAGE__SECRET", "mutable-content": 1, "alert":"received encrypted message"}, "data": {"test":"123"}}' --http2 https://${APNS_HOST_NAME}/3/device/${DEVICE_TOKEN}

src/Simplex/Messaging/Notifications/Server/Store.hs

@@ -0,0 +1,155 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+
+module Simplex.Messaging.Notifications.Server.Store where
+
+import Control.Concurrent.STM
+import Control.Monad
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.Map.Strict as M
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Notifications.Protocol
+import Simplex.Messaging.TMap (TMap)
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Util (whenM, ($>>=))
+
+data NtfStore = NtfStore
+  { tokens :: TMap NtfTokenId NtfTknData,
+    tokenRegistrations :: TMap DeviceToken (TMap ByteString NtfTokenId)
+  }
+
+newNtfStore :: STM NtfStore
+newNtfStore = do
+  tokens <- TM.empty
+  tokenRegistrations <- TM.empty
+  pure NtfStore {tokens, tokenRegistrations}
+
+data NtfTknData = NtfTknData
+  { ntfTknId :: NtfTokenId,
+    token :: DeviceToken,
+    tknStatus :: TVar NtfTknStatus,
+    tknVerifyKey :: C.APublicVerifyKey,
+    tknDhKeys :: C.KeyPair 'C.X25519,
+    tknDhSecret :: C.DhSecretX25519,
+    tknRegCode :: NtfRegCode
+  }
+
+mkNtfTknData :: NtfTokenId -> NewNtfEntity 'Token -> C.KeyPair 'C.X25519 -> C.DhSecretX25519 -> NtfRegCode -> STM NtfTknData
+mkNtfTknData ntfTknId (NewNtfTkn token tknVerifyKey _) tknDhKeys tknDhSecret tknRegCode = do
+  tknStatus <- newTVar NTRegistered
+  pure NtfTknData {ntfTknId, token, tknStatus, tknVerifyKey, tknDhKeys, tknDhSecret, tknRegCode}
+
+-- data NtfSubscriptionsStore = NtfSubscriptionsStore
+
+-- { subscriptions :: TMap NtfSubsciptionId NtfSubsciption,
+--   activeSubscriptions :: TMap (SMPServer, NotifierId) NtfSubsciptionId
+-- }
+-- do
+-- subscriptions <- newTVar M.empty
+-- activeSubscriptions <- newTVar M.empty
+-- pure NtfSubscriptionsStore {subscriptions, activeSubscriptions}
+
+data NtfSubData = NtfSubData
+  { smpQueue :: SMPQueueNtf,
+    tokenId :: NtfTokenId,
+    subStatus :: TVar NtfSubStatus
+  }
+
+data NtfEntityRec (e :: NtfEntity) where
+  NtfTkn :: NtfTknData -> NtfEntityRec 'Token
+  NtfSub :: NtfSubData -> NtfEntityRec 'Subscription
+
+getNtfToken :: NtfStore -> NtfTokenId -> STM (Maybe NtfTknData)
+getNtfToken st tknId = TM.lookup tknId (tokens st)
+
+addNtfToken :: NtfStore -> NtfTokenId -> NtfTknData -> STM ()
+addNtfToken st tknId tkn@NtfTknData {token, tknVerifyKey} = do
+  TM.insert tknId tkn $ tokens st
+  TM.lookup token regs >>= \case
+    Just tIds -> TM.insert regKey tknId tIds
+    _ -> do
+      tIds <- TM.singleton regKey tknId
+      TM.insert token tIds regs
+  where
+    regs = tokenRegistrations st
+    regKey = C.toPubKey C.pubKeyBytes tknVerifyKey
+
+getNtfTokenRegistration :: NtfStore -> NewNtfEntity 'Token -> STM (Maybe NtfTknData)
+getNtfTokenRegistration st (NewNtfTkn token tknVerifyKey _) =
+  TM.lookup token (tokenRegistrations st)
+    $>>= TM.lookup regKey
+    $>>= (`TM.lookup` tokens st)
+  where
+    regKey = C.toPubKey C.pubKeyBytes tknVerifyKey
+
+removeInactiveTokenRegistrations :: NtfStore -> NtfTknData -> STM [NtfTokenId]
+removeInactiveTokenRegistrations st NtfTknData {ntfTknId = tId, token} =
+  TM.lookup token (tokenRegistrations st)
+    >>= maybe (pure []) removeRegs
+  where
+    removeRegs :: TMap ByteString NtfTokenId -> STM [NtfTokenId]
+    removeRegs tknRegs = do
+      tIds <- filter ((/= tId) . snd) . M.assocs <$> readTVar tknRegs
+      forM_ tIds $ \(regKey, tId') -> do
+        TM.delete regKey tknRegs
+        TM.delete tId' $ tokens st
+      pure $ map snd tIds
+
+deleteNtfToken :: NtfStore -> NtfTokenId -> STM ()
+deleteNtfToken st tknId = do
+  TM.lookupDelete tknId (tokens st)
+    >>= mapM_
+      ( \NtfTknData {token, tknVerifyKey} ->
+          TM.lookup token regs
+            >>= mapM_
+              ( \tIds -> do
+                  TM.delete (regKey tknVerifyKey) tIds
+                  whenM (TM.null tIds) $ TM.delete token regs
+              )
+      )
+  where
+    regs = tokenRegistrations st
+    regKey = C.toPubKey C.pubKeyBytes
+
+-- getNtfRec :: NtfStore -> SNtfEntity e -> NtfEntityId -> STM (Maybe (NtfEntityRec e))
+-- getNtfRec st ent entId = case ent of
+--   SToken -> NtfTkn <$$> TM.lookup entId (tokens st)
+--   SSubscription -> pure Nothing
+
+-- getNtfVerifyKey :: NtfStore -> SNtfEntity e -> NtfEntityId -> STM (Maybe (NtfEntityRec e, C.APublicVerifyKey))
+-- getNtfVerifyKey st ent entId =
+--   getNtfRec st ent entId >>= \case
+--     Just r@(NtfTkn NtfTknData {tknVerifyKey}) -> pure $ Just (r, tknVerifyKey)
+--     Just r@(NtfSub NtfSubData {tokenId}) ->
+--       getNtfRec st SToken tokenId >>= \case
+--         Just (NtfTkn NtfTknData {tknVerifyKey}) -> pure $ Just (r, tknVerifyKey)
+--         _ -> pure Nothing
+--     _ -> pure Nothing
+
+-- mkNtfSubsciption :: SMPQueueNtf -> NtfTokenId -> STM NtfSubsciption
+-- mkNtfSubsciption smpQueue tokenId = do
+--   subStatus <- newTVar NSNew
+--   pure NtfSubsciption {smpQueue, tokenId, subStatus}
+
+-- getNtfSub :: NtfSubscriptionsStore -> NtfSubsciptionId -> STM (Maybe NtfSubsciption)
+-- getNtfSub st subId = pure Nothing -- maybe (pure $ Left AUTH) (fmap Right . readTVar) . M.lookup subId . subscriptions =<< readTVar st
+
+-- getNtfSubViaSMPQueue :: NtfSubscriptionsStore -> SMPQueueNtf -> STM (Maybe NtfSubsciption)
+-- getNtfSubViaSMPQueue st smpQueue = pure Nothing
+
+-- -- replace keeping status
+-- updateNtfSub :: NtfSubscriptionsStore -> NtfSubsciption -> SMPQueueNtf -> NtfTokenId -> C.DhSecretX25519 -> STM (Maybe ())
+-- updateNtfSub st sub smpQueue tokenId dhSecret = pure Nothing
+
+-- addNtfSub :: NtfSubscriptionsStore -> NtfSubsciptionId -> NtfSubsciption -> STM (Maybe ())
+-- addNtfSub st subId sub = pure Nothing
+
+-- deleteNtfSub :: NtfSubscriptionsStore -> NtfSubsciptionId -> STM ()
+-- deleteNtfSub st subId = pure ()

src/Simplex/Messaging/Notifications/Transport.hs

@@ -0,0 +1,19 @@
+module Simplex.Messaging.Notifications.Transport where
+
+import Control.Monad.Except
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Transport
+
+ntfBlockSize :: Int
+ntfBlockSize = 512
+
+-- | Notifcations server transport handshake.
+ntfServerHandshake :: Transport c => c -> C.KeyHash -> ExceptT TransportError IO (THandle c)
+ntfServerHandshake c _ = pure $ ntfTHandle c
+
+-- | Notifcations server client transport handshake.
+ntfClientHandshake :: Transport c => c -> C.KeyHash -> ExceptT TransportError IO (THandle c)
+ntfClientHandshake c _ = pure $ ntfTHandle c
+
+ntfTHandle :: Transport c => c -> THandle c
+ntfTHandle c = THandle {connection = c, sessionId = tlsUnique c, blockSize = ntfBlockSize, thVersion = 0}

src/Simplex/Messaging/Parsers.hs

@@ -0,0 +1,135 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Simplex.Messaging.Parsers where
+
+import Control.Monad.Trans.Except
+import qualified Data.Aeson as J
+import Data.Attoparsec.ByteString.Char8 (Parser)
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.Bifunctor (first)
+import Data.ByteString.Base64
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Char (isAlphaNum, toLower)
+import Data.Text (Text)
+import qualified Data.Text as T
+import Data.Time.Clock (UTCTime)
+import Data.Time.ISO8601 (parseISO8601)
+import Data.Typeable (Typeable)
+import Database.SQLite.Simple (ResultError (..), SQLData (..))
+import Database.SQLite.Simple.FromField (FieldParser, returnError)
+import Database.SQLite.Simple.Internal (Field (..))
+import Database.SQLite.Simple.Ok (Ok (Ok))
+import Simplex.Messaging.Util ((<$?>))
+import Text.Read (readMaybe)
+
+base64P :: Parser ByteString
+base64P = decode <$?> paddedBase64 rawBase64P
+
+paddedBase64 :: Parser ByteString -> Parser ByteString
+paddedBase64 raw = (<>) <$> raw <*> pad
+  where
+    pad = A.takeWhile (== '=')
+
+rawBase64P :: Parser ByteString
+rawBase64P = A.takeWhile1 (\c -> isAlphaNum c || c == '+' || c == '/')
+
+-- rawBase64UriP :: Parser ByteString
+-- rawBase64UriP = A.takeWhile1 (\c -> isAlphaNum c || c == '-' || c == '_')
+
+tsISO8601P :: Parser UTCTime
+tsISO8601P = maybe (fail "timestamp") pure . parseISO8601 . B.unpack =<< A.takeTill wordEnd
+
+parse :: Parser a -> e -> (ByteString -> Either e a)
+parse parser err = first (const err) . parseAll parser
+
+parseAll :: Parser a -> (ByteString -> Either String a)
+parseAll parser = A.parseOnly (parser <* A.endOfInput)
+
+parseE :: (String -> e) -> Parser a -> (ByteString -> ExceptT e IO a)
+parseE err parser = except . first err . parseAll parser
+
+parseE' :: (String -> e) -> Parser a -> (ByteString -> ExceptT e IO a)
+parseE' err parser = except . first err . A.parseOnly parser
+
+parseRead :: Read a => Parser ByteString -> Parser a
+parseRead = (>>= maybe (fail "cannot read") pure . readMaybe . B.unpack)
+
+parseRead1 :: Read a => Parser a
+parseRead1 = parseRead $ A.takeTill wordEnd
+
+parseRead2 :: Read a => Parser a
+parseRead2 = parseRead $ do
+  w1 <- A.takeTill wordEnd <* A.char ' '
+  w2 <- A.takeTill wordEnd
+  pure $ w1 <> " " <> w2
+
+wordEnd :: Char -> Bool
+wordEnd c = c == ' ' || c == '\n'
+
+parseString :: (ByteString -> Either String a) -> (String -> a)
+parseString p = either error id . p . B.pack
+
+blobFieldParser :: Typeable k => Parser k -> FieldParser k
+blobFieldParser = blobFieldDecoder . parseAll
+
+blobFieldDecoder :: Typeable k => (ByteString -> Either String k) -> FieldParser k
+blobFieldDecoder dec = \case
+  f@(Field (SQLBlob b) _) ->
+    case dec b of
+      Right k -> Ok k
+      Left e -> returnError ConversionFailed f ("couldn't parse field: " ++ e)
+  f -> returnError ConversionFailed f "expecting SQLBlob column type"
+
+fromTextField_ :: (Typeable a) => (Text -> Maybe a) -> Field -> Ok a
+fromTextField_ fromText = \case
+  f@(Field (SQLText t) _) ->
+    case fromText t of
+      Just x -> Ok x
+      _ -> returnError ConversionFailed f ("invalid text: " <> T.unpack t)
+  f -> returnError ConversionFailed f "expecting SQLText column type"
+
+fstToLower :: String -> String
+fstToLower "" = ""
+fstToLower (h : t) = toLower h : t
+
+dropPrefix :: String -> String -> String
+dropPrefix pfx s =
+  let (p, rest) = splitAt (length pfx) s
+   in fstToLower $ if p == pfx then rest else s
+
+enumJSON :: (String -> String) -> J.Options
+enumJSON tagModifier =
+  J.defaultOptions
+    { J.constructorTagModifier = tagModifier,
+      J.allNullaryToStringTag = True
+    }
+
+sumTypeJSON :: (String -> String) -> J.Options
+#if defined(darwin_HOST_OS) && defined(swiftJSON)
+sumTypeJSON = singleFieldJSON
+#else
+sumTypeJSON = taggedObjectJSON
+#endif
+
+taggedObjectJSON :: (String -> String) -> J.Options
+taggedObjectJSON tagModifier =
+  J.defaultOptions
+    { J.sumEncoding = J.TaggedObject "type" "data",
+      J.constructorTagModifier = tagModifier,
+      J.allNullaryToStringTag = False,
+      J.nullaryToObject = True,
+      J.omitNothingFields = True
+    }
+
+singleFieldJSON :: (String -> String) -> J.Options
+singleFieldJSON tagModifier =
+  J.defaultOptions
+    { J.sumEncoding = J.ObjectWithSingleField,
+      J.constructorTagModifier = tagModifier,
+      J.allNullaryToStringTag = False,
+      J.nullaryToObject = True,
+      J.omitNothingFields = True
+    }

src/Simplex/Messaging/Protocol.hs

@@ -0,0 +1,772 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE PolyKinds #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilyDependencies #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}
+
+-- |
+-- Module      : Simplex.Messaging.ProtocolEncoding
+-- Copyright   : (c) simplex.chat
+-- License     : AGPL-3
+--
+-- Maintainer  : chat@simplex.chat
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Types, parsers, serializers and functions to send and receive SMP protocol commands and responses.
+--
+-- See https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md
+module Simplex.Messaging.Protocol
+  ( -- * SMP protocol parameters
+    smpClientVersion,
+    smpClientVRange,
+    maxMessageLength,
+    e2eEncConfirmationLength,
+    e2eEncMessageLength,
+
+    -- * SMP protocol types
+    ProtocolEncoding (..),
+    Command (..),
+    Party (..),
+    Cmd (..),
+    BrokerMsg (..),
+    SParty (..),
+    PartyI (..),
+    QueueIdsKeys (..),
+    ErrorType (..),
+    CommandError (..),
+    Transmission,
+    SignedTransmission,
+    SentRawTransmission,
+    SignedRawTransmission,
+    ClientMsgEnvelope (..),
+    PubHeader (..),
+    ClientMessage (..),
+    PrivHeader (..),
+    Protocol (..),
+    ProtocolServer (..),
+    SMPServer,
+    pattern SMPServer,
+    SrvLoc (..),
+    CorrId (..),
+    QueueId,
+    RecipientId,
+    SenderId,
+    NotifierId,
+    RcvPrivateSignKey,
+    RcvPublicVerifyKey,
+    RcvPublicDhKey,
+    RcvDhSecret,
+    SndPrivateSignKey,
+    SndPublicVerifyKey,
+    NtfPrivateSignKey,
+    NtfPublicVerifyKey,
+    MsgId,
+    MsgBody,
+
+    -- * Parse and serialize
+    ProtocolMsgTag (..),
+    messageTagP,
+    encodeTransmission,
+    transmissionP,
+    _smpP,
+
+    -- * TCP transport functions
+    tPut,
+    tGet,
+
+    -- * exports for tests
+    CommandTag (..),
+    BrokerMsgTag (..),
+  )
+where
+
+import Control.Applicative (optional, (<|>))
+import Control.Monad.Except
+import Data.Aeson (ToJSON (..))
+import qualified Data.Aeson as J
+import Data.Attoparsec.ByteString.Char8 (Parser)
+import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Kind
+import Data.Maybe (isNothing)
+import Data.String
+import Data.Time.Clock.System (SystemTime)
+import Data.Type.Equality
+import GHC.Generics (Generic)
+import Generic.Random (genericArbitraryU)
+import Network.Socket (HostName, ServiceName)
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Parsers
+import Simplex.Messaging.Transport
+import Simplex.Messaging.Util (bshow, (<$?>))
+import Simplex.Messaging.Version
+import Test.QuickCheck (Arbitrary (..))
+
+smpClientVersion :: Version
+smpClientVersion = 1
+
+smpClientVRange :: VersionRange
+smpClientVRange = mkVersionRange 1 smpClientVersion
+
+maxMessageLength :: Int
+maxMessageLength = 16088
+
+-- it is shorter to allow per-queue e2e encryption DH key in the "public" header
+e2eEncConfirmationLength :: Int
+e2eEncConfirmationLength = 15936
+
+e2eEncMessageLength :: Int
+e2eEncMessageLength = 16032
+
+-- | SMP protocol clients
+data Party = Recipient | Sender | Notifier
+  deriving (Show)
+
+-- | Singleton types for SMP protocol clients
+data SParty :: Party -> Type where
+  SRecipient :: SParty Recipient
+  SSender :: SParty Sender
+  SNotifier :: SParty Notifier
+
+instance TestEquality SParty where
+  testEquality SRecipient SRecipient = Just Refl
+  testEquality SSender SSender = Just Refl
+  testEquality SNotifier SNotifier = Just Refl
+  testEquality _ _ = Nothing
+
+deriving instance Show (SParty p)
+
+class PartyI (p :: Party) where sParty :: SParty p
+
+instance PartyI Recipient where sParty = SRecipient
+
+instance PartyI Sender where sParty = SSender
+
+instance PartyI Notifier where sParty = SNotifier
+
+-- | Type for client command of any participant.
+data Cmd = forall p. PartyI p => Cmd (SParty p) (Command p)
+
+deriving instance Show Cmd
+
+-- | Parsed SMP transmission without signature, size and session ID.
+type Transmission c = (CorrId, EntityId, c)
+
+-- | signed parsed transmission, with original raw bytes and parsing error.
+type SignedTransmission c = (Maybe C.ASignature, Signed, Transmission (Either ErrorType c))
+
+type Signed = ByteString
+
+-- | unparsed SMP transmission with signature.
+data RawTransmission = RawTransmission
+  { signature :: ByteString,
+    signed :: ByteString,
+    sessId :: SessionId,
+    corrId :: ByteString,
+    entityId :: ByteString,
+    command :: ByteString
+  }
+  deriving (Show)
+
+-- | unparsed sent SMP transmission with signature, without session ID.
+type SignedRawTransmission = (Maybe C.ASignature, SessionId, ByteString, ByteString)
+
+-- | unparsed sent SMP transmission with signature.
+type SentRawTransmission = (Maybe C.ASignature, ByteString)
+
+-- | SMP queue ID for the recipient.
+type RecipientId = QueueId
+
+-- | SMP queue ID for the sender.
+type SenderId = QueueId
+
+-- | SMP queue ID for notifications.
+type NotifierId = QueueId
+
+-- | SMP queue ID on the server.
+type QueueId = EntityId
+
+type EntityId = ByteString
+
+-- | Parameterized type for SMP protocol commands from all clients.
+data Command (p :: Party) where
+  -- SMP recipient commands
+  NEW :: RcvPublicVerifyKey -> RcvPublicDhKey -> Command Recipient
+  SUB :: Command Recipient
+  KEY :: SndPublicVerifyKey -> Command Recipient
+  NKEY :: NtfPublicVerifyKey -> Command Recipient
+  ACK :: Command Recipient
+  OFF :: Command Recipient
+  DEL :: Command Recipient
+  -- SMP sender commands
+  SEND :: MsgBody -> Command Sender
+  PING :: Command Sender
+  -- SMP notification subscriber commands
+  NSUB :: Command Notifier
+
+deriving instance Show (Command p)
+
+deriving instance Eq (Command p)
+
+data BrokerMsg where
+  -- SMP broker messages (responses, client messages, notifications)
+  IDS :: QueueIdsKeys -> BrokerMsg
+  MSG :: MsgId -> SystemTime -> MsgBody -> BrokerMsg
+  NID :: NotifierId -> BrokerMsg
+  NMSG :: BrokerMsg
+  END :: BrokerMsg
+  OK :: BrokerMsg
+  ERR :: ErrorType -> BrokerMsg
+  PONG :: BrokerMsg
+  deriving (Eq, Show)
+
+-- * SMP command tags
+
+data CommandTag (p :: Party) where
+  NEW_ :: CommandTag Recipient
+  SUB_ :: CommandTag Recipient
+  KEY_ :: CommandTag Recipient
+  NKEY_ :: CommandTag Recipient
+  ACK_ :: CommandTag Recipient
+  OFF_ :: CommandTag Recipient
+  DEL_ :: CommandTag Recipient
+  SEND_ :: CommandTag Sender
+  PING_ :: CommandTag Sender
+  NSUB_ :: CommandTag Notifier
+
+data CmdTag = forall p. PartyI p => CT (SParty p) (CommandTag p)
+
+deriving instance Show (CommandTag p)
+
+deriving instance Show CmdTag
+
+data BrokerMsgTag
+  = IDS_
+  | MSG_
+  | NID_
+  | NMSG_
+  | END_
+  | OK_
+  | ERR_
+  | PONG_
+  deriving (Show)
+
+class ProtocolMsgTag t where
+  decodeTag :: ByteString -> Maybe t
+
+messageTagP :: ProtocolMsgTag t => Parser t
+messageTagP =
+  maybe (fail "bad message") pure . decodeTag
+    =<< (A.takeTill (== ' ') <* optional A.space)
+
+instance PartyI p => Encoding (CommandTag p) where
+  smpEncode = \case
+    NEW_ -> "NEW"
+    SUB_ -> "SUB"
+    KEY_ -> "KEY"
+    NKEY_ -> "NKEY"
+    ACK_ -> "ACK"
+    OFF_ -> "OFF"
+    DEL_ -> "DEL"
+    SEND_ -> "SEND"
+    PING_ -> "PING"
+    NSUB_ -> "NSUB"
+  smpP = messageTagP
+
+instance ProtocolMsgTag CmdTag where
+  decodeTag = \case
+    "NEW" -> Just $ CT SRecipient NEW_
+    "SUB" -> Just $ CT SRecipient SUB_
+    "KEY" -> Just $ CT SRecipient KEY_
+    "NKEY" -> Just $ CT SRecipient NKEY_
+    "ACK" -> Just $ CT SRecipient ACK_
+    "OFF" -> Just $ CT SRecipient OFF_
+    "DEL" -> Just $ CT SRecipient DEL_
+    "SEND" -> Just $ CT SSender SEND_
+    "PING" -> Just $ CT SSender PING_
+    "NSUB" -> Just $ CT SNotifier NSUB_
+    _ -> Nothing
+
+instance Encoding CmdTag where
+  smpEncode (CT _ t) = smpEncode t
+  smpP = messageTagP
+
+instance PartyI p => ProtocolMsgTag (CommandTag p) where
+  decodeTag s = decodeTag s >>= (\(CT _ t) -> checkParty' t)
+
+instance Encoding BrokerMsgTag where
+  smpEncode = \case
+    IDS_ -> "IDS"
+    MSG_ -> "MSG"
+    NID_ -> "NID"
+    NMSG_ -> "NMSG"
+    END_ -> "END"
+    OK_ -> "OK"
+    ERR_ -> "ERR"
+    PONG_ -> "PONG"
+  smpP = messageTagP
+
+instance ProtocolMsgTag BrokerMsgTag where
+  decodeTag = \case
+    "IDS" -> Just IDS_
+    "MSG" -> Just MSG_
+    "NID" -> Just NID_
+    "NMSG" -> Just NMSG_
+    "END" -> Just END_
+    "OK" -> Just OK_
+    "ERR" -> Just ERR_
+    "PONG" -> Just PONG_
+    _ -> Nothing
+
+-- | SMP message body format
+data ClientMsgEnvelope = ClientMsgEnvelope
+  { cmHeader :: PubHeader,
+    cmNonce :: C.CbNonce,
+    cmEncBody :: ByteString
+  }
+  deriving (Show)
+
+data PubHeader = PubHeader
+  { phVersion :: Version,
+    phE2ePubDhKey :: Maybe C.PublicKeyX25519
+  }
+  deriving (Show)
+
+instance Encoding PubHeader where
+  smpEncode (PubHeader v k) = smpEncode (v, k)
+  smpP = PubHeader <$> smpP <*> smpP
+
+instance Encoding ClientMsgEnvelope where
+  smpEncode ClientMsgEnvelope {cmHeader, cmNonce, cmEncBody} =
+    smpEncode (cmHeader, cmNonce, Tail cmEncBody)
+  smpP = do
+    (cmHeader, cmNonce, Tail cmEncBody) <- smpP
+    pure ClientMsgEnvelope {cmHeader, cmNonce, cmEncBody}
+
+data ClientMessage = ClientMessage PrivHeader ByteString
+
+data PrivHeader
+  = PHConfirmation C.APublicVerifyKey
+  | PHEmpty
+  deriving (Show)
+
+instance Encoding PrivHeader where
+  smpEncode = \case
+    PHConfirmation k -> "K" <> smpEncode k
+    PHEmpty -> "_"
+  smpP =
+    A.anyChar >>= \case
+      'K' -> PHConfirmation <$> smpP
+      '_' -> pure PHEmpty
+      _ -> fail "invalid PrivHeader"
+
+instance Encoding ClientMessage where
+  smpEncode (ClientMessage h msg) = smpEncode h <> msg
+  smpP = ClientMessage <$> smpP <*> A.takeByteString
+
+type SMPServer = ProtocolServer
+
+pattern SMPServer :: HostName -> ServiceName -> C.KeyHash -> ProtocolServer
+pattern SMPServer host port keyHash = ProtocolServer host port keyHash
+
+{-# COMPLETE SMPServer #-}
+
+-- | SMP server location and transport key digest (hash).
+data ProtocolServer = ProtocolServer
+  { host :: HostName,
+    port :: ServiceName,
+    keyHash :: C.KeyHash
+  }
+  deriving (Eq, Ord, Show)
+
+instance IsString ProtocolServer where
+  fromString = parseString strDecode
+
+instance Encoding ProtocolServer where
+  smpEncode ProtocolServer {host, port, keyHash} =
+    smpEncode (host, port, keyHash)
+  smpP = do
+    (host, port, keyHash) <- smpP
+    pure ProtocolServer {host, port, keyHash}
+
+instance StrEncoding ProtocolServer where
+  strEncode ProtocolServer {host, port, keyHash} =
+    "smp://" <> strEncode keyHash <> "@" <> strEncode (SrvLoc host port)
+  strP = do
+    _ <- "smp://"
+    keyHash <- strP <* A.char '@'
+    SrvLoc host port <- strP
+    pure ProtocolServer {host, port, keyHash}
+
+instance ToJSON ProtocolServer where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+data SrvLoc = SrvLoc HostName ServiceName
+  deriving (Eq, Ord, Show)
+
+instance StrEncoding SrvLoc where
+  strEncode (SrvLoc host port) = B.pack $ host <> if null port then "" else ':' : port
+  strP = SrvLoc <$> host <*> (port <|> pure "")
+    where
+      host = B.unpack <$> A.takeWhile1 (A.notInClass ":#,;/ ")
+      port = B.unpack <$> (A.char ':' *> A.takeWhile1 A.isDigit)
+
+-- | Transmission correlation ID.
+newtype CorrId = CorrId {bs :: ByteString} deriving (Eq, Ord, Show)
+
+instance IsString CorrId where
+  fromString = CorrId . fromString
+
+instance StrEncoding CorrId where
+  strEncode (CorrId cId) = strEncode cId
+  strDecode s = CorrId <$> strDecode s
+  strP = CorrId <$> strP
+
+instance ToJSON CorrId where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
+-- | Queue IDs and keys
+data QueueIdsKeys = QIK
+  { rcvId :: RecipientId,
+    sndId :: SenderId,
+    rcvPublicDhKey :: RcvPublicDhKey
+  }
+  deriving (Eq, Show)
+
+-- | Recipient's private key used by the recipient to authorize (sign) SMP commands.
+--
+-- Only used by SMP agent, kept here so its definition is close to respective public key.
+type RcvPrivateSignKey = C.APrivateSignKey
+
+-- | Recipient's public key used by SMP server to verify authorization of SMP commands.
+type RcvPublicVerifyKey = C.APublicVerifyKey
+
+-- | Public key used for DH exchange to encrypt message bodies from server to recipient
+type RcvPublicDhKey = C.PublicKeyX25519
+
+-- | DH Secret used to encrypt message bodies from server to recipient
+type RcvDhSecret = C.DhSecretX25519
+
+-- | Sender's private key used by the recipient to authorize (sign) SMP commands.
+--
+-- Only used by SMP agent, kept here so its definition is close to respective public key.
+type SndPrivateSignKey = C.APrivateSignKey
+
+-- | Sender's public key used by SMP server to verify authorization of SMP commands.
+type SndPublicVerifyKey = C.APublicVerifyKey
+
+-- | Private key used by push notifications server to authorize (sign) LSTN command.
+type NtfPrivateSignKey = C.APrivateSignKey
+
+-- | Public key used by SMP server to verify authorization of LSTN command sent by push notifications server.
+type NtfPublicVerifyKey = C.APublicVerifyKey
+
+-- | SMP message server ID.
+type MsgId = ByteString
+
+-- | SMP message body.
+type MsgBody = ByteString
+
+-- | Type for protocol errors.
+data ErrorType
+  = -- | incorrect block format, encoding or signature size
+    BLOCK
+  | -- | incorrect SMP session ID (TLS Finished message / tls-unique binding RFC5929)
+    SESSION
+  | -- | SMP command is unknown or has invalid syntax
+    CMD {cmdErr :: CommandError}
+  | -- | command authorization error - bad signature or non-existing SMP queue
+    AUTH
+  | -- | SMP queue capacity is exceeded on the server
+    QUOTA
+  | -- | ACK command is sent without message to be acknowledged
+    NO_MSG
+  | -- | sent message is too large (> maxMessageLength = 16078 bytes)
+    LARGE_MSG
+  | -- | internal server error
+    INTERNAL
+  | -- | used internally, never returned by the server (to be removed)
+    DUPLICATE_ -- TODO remove, not part of SMP protocol
+  deriving (Eq, Generic, Read, Show)
+
+instance ToJSON ErrorType where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+instance StrEncoding ErrorType where
+  strEncode = \case
+    CMD e -> "CMD " <> bshow e
+    e -> bshow e
+  strP = "CMD " *> (CMD <$> parseRead1) <|> parseRead1
+
+-- | SMP command error type.
+data CommandError
+  = -- | unknown command
+    UNKNOWN
+  | -- | error parsing command
+    SYNTAX
+  | -- | transmission has no required credentials (signature or queue ID)
+    NO_AUTH
+  | -- | transmission has credentials that are not allowed for this command
+    HAS_AUTH
+  | -- | transmission has no required entity ID (e.g. SMP queue)
+    NO_ENTITY
+  deriving (Eq, Generic, Read, Show)
+
+instance ToJSON CommandError where
+  toJSON = J.genericToJSON $ sumTypeJSON id
+  toEncoding = J.genericToEncoding $ sumTypeJSON id
+
+instance Arbitrary ErrorType where arbitrary = genericArbitraryU
+
+instance Arbitrary CommandError where arbitrary = genericArbitraryU
+
+-- | SMP transmission parser.
+transmissionP :: Parser RawTransmission
+transmissionP = do
+  signature <- smpP
+  signed <- A.takeByteString
+  either fail pure $ parseAll (trn signature signed) signed
+  where
+    trn signature signed = do
+      sessId <- smpP
+      corrId <- smpP
+      entityId <- smpP
+      command <- A.takeByteString
+      pure RawTransmission {signature, signed, sessId, corrId, entityId, command}
+
+class (ProtocolEncoding msg, ProtocolEncoding (ProtocolCommand msg)) => Protocol msg where
+  type ProtocolCommand msg = cmd | cmd -> msg
+  protocolClientHandshake :: forall c. Transport c => c -> C.KeyHash -> ExceptT TransportError IO (THandle c)
+  protocolPing :: ProtocolCommand msg
+  protocolError :: msg -> Maybe ErrorType
+
+instance Protocol BrokerMsg where
+  type ProtocolCommand BrokerMsg = Cmd
+  protocolClientHandshake = smpClientHandshake
+  protocolPing = Cmd SSender PING
+  protocolError = \case
+    ERR e -> Just e
+    _ -> Nothing
+
+class ProtocolMsgTag (Tag msg) => ProtocolEncoding msg where
+  type Tag msg
+  encodeProtocol :: msg -> ByteString
+  protocolP :: Tag msg -> Parser msg
+  checkCredentials :: SignedRawTransmission -> msg -> Either ErrorType msg
+
+instance PartyI p => ProtocolEncoding (Command p) where
+  type Tag (Command p) = CommandTag p
+  encodeProtocol = \case
+    NEW rKey dhKey -> e (NEW_, ' ', rKey, dhKey)
+    SUB -> e SUB_
+    KEY k -> e (KEY_, ' ', k)
+    NKEY k -> e (NKEY_, ' ', k)
+    ACK -> e ACK_
+    OFF -> e OFF_
+    DEL -> e DEL_
+    SEND msg -> e (SEND_, ' ', Tail msg)
+    PING -> e PING_
+    NSUB -> e NSUB_
+    where
+      e :: Encoding a => a -> ByteString
+      e = smpEncode
+
+  protocolP tag = (\(Cmd _ c) -> checkParty c) <$?> protocolP (CT (sParty @p) tag)
+
+  checkCredentials (sig, _, queueId, _) cmd = case cmd of
+    -- NEW must have signature but NOT queue ID
+    NEW {}
+      | isNothing sig -> Left $ CMD NO_AUTH
+      | not (B.null queueId) -> Left $ CMD HAS_AUTH
+      | otherwise -> Right cmd
+    -- SEND must have queue ID, signature is not always required
+    SEND _
+      | B.null queueId -> Left $ CMD NO_ENTITY
+      | otherwise -> Right cmd
+    -- PING must not have queue ID or signature
+    PING
+      | isNothing sig && B.null queueId -> Right cmd
+      | otherwise -> Left $ CMD HAS_AUTH
+    -- other client commands must have both signature and queue ID
+    _
+      | isNothing sig || B.null queueId -> Left $ CMD NO_AUTH
+      | otherwise -> Right cmd
+
+instance ProtocolEncoding Cmd where
+  type Tag Cmd = CmdTag
+  encodeProtocol (Cmd _ c) = encodeProtocol c
+
+  protocolP = \case
+    CT SRecipient tag ->
+      Cmd SRecipient <$> case tag of
+        NEW_ -> NEW <$> _smpP <*> smpP
+        SUB_ -> pure SUB
+        KEY_ -> KEY <$> _smpP
+        NKEY_ -> NKEY <$> _smpP
+        ACK_ -> pure ACK
+        OFF_ -> pure OFF
+        DEL_ -> pure DEL
+    CT SSender tag ->
+      Cmd SSender <$> case tag of
+        SEND_ -> SEND . unTail <$> _smpP
+        PING_ -> pure PING
+    CT SNotifier NSUB_ -> pure $ Cmd SNotifier NSUB
+
+  checkCredentials t (Cmd p c) = Cmd p <$> checkCredentials t c
+
+instance ProtocolEncoding BrokerMsg where
+  type Tag BrokerMsg = BrokerMsgTag
+  encodeProtocol = \case
+    IDS (QIK rcvId sndId srvDh) -> e (IDS_, ' ', rcvId, sndId, srvDh)
+    MSG msgId ts msgBody -> e (MSG_, ' ', msgId, ts, Tail msgBody)
+    NID nId -> e (NID_, ' ', nId)
+    NMSG -> e NMSG_
+    END -> e END_
+    OK -> e OK_
+    ERR err -> e (ERR_, ' ', err)
+    PONG -> e PONG_
+    where
+      e :: Encoding a => a -> ByteString
+      e = smpEncode
+
+  protocolP = \case
+    MSG_ -> MSG <$> _smpP <*> smpP <*> (unTail <$> smpP)
+    IDS_ -> IDS <$> (QIK <$> _smpP <*> smpP <*> smpP)
+    NID_ -> NID <$> _smpP
+    NMSG_ -> pure NMSG
+    END_ -> pure END
+    OK_ -> pure OK
+    ERR_ -> ERR <$> _smpP
+    PONG_ -> pure PONG
+
+  checkCredentials (_, _, queueId, _) cmd = case cmd of
+    -- IDS response should not have queue ID
+    IDS _ -> Right cmd
+    -- ERR response does not always have queue ID
+    ERR _ -> Right cmd
+    -- PONG response must not have queue ID
+    PONG
+      | B.null queueId -> Right cmd
+      | otherwise -> Left $ CMD HAS_AUTH
+    -- other broker responses must have queue ID
+    _
+      | B.null queueId -> Left $ CMD NO_ENTITY
+      | otherwise -> Right cmd
+
+_smpP :: Encoding a => Parser a
+_smpP = A.space *> smpP
+
+-- | Parse SMP protocol commands and broker messages
+parseProtocol :: ProtocolEncoding msg => ByteString -> Either ErrorType msg
+parseProtocol s =
+  let (tag, params) = B.break (== ' ') s
+   in case decodeTag tag of
+        Just cmd -> parse (protocolP cmd) (CMD SYNTAX) params
+        Nothing -> Left $ CMD UNKNOWN
+
+checkParty :: forall t p p'. (PartyI p, PartyI p') => t p' -> Either String (t p)
+checkParty c = case testEquality (sParty @p) (sParty @p') of
+  Just Refl -> Right c
+  Nothing -> Left "bad command party"
+
+checkParty' :: forall t p p'. (PartyI p, PartyI p') => t p' -> Maybe (t p)
+checkParty' c = case testEquality (sParty @p) (sParty @p') of
+  Just Refl -> Just c
+  _ -> Nothing
+
+instance Encoding ErrorType where
+  smpEncode = \case
+    BLOCK -> "BLOCK"
+    SESSION -> "SESSION"
+    CMD err -> "CMD " <> smpEncode err
+    AUTH -> "AUTH"
+    QUOTA -> "QUOTA"
+    NO_MSG -> "NO_MSG"
+    LARGE_MSG -> "LARGE_MSG"
+    INTERNAL -> "INTERNAL"
+    DUPLICATE_ -> "DUPLICATE_"
+
+  smpP =
+    A.takeTill (== ' ') >>= \case
+      "BLOCK" -> pure BLOCK
+      "SESSION" -> pure SESSION
+      "CMD" -> CMD <$> _smpP
+      "AUTH" -> pure AUTH
+      "QUOTA" -> pure QUOTA
+      "NO_MSG" -> pure NO_MSG
+      "LARGE_MSG" -> pure LARGE_MSG
+      "INTERNAL" -> pure INTERNAL
+      "DUPLICATE_" -> pure DUPLICATE_
+      _ -> fail "bad error type"
+
+instance Encoding CommandError where
+  smpEncode e = case e of
+    UNKNOWN -> "UNKNOWN"
+    SYNTAX -> "SYNTAX"
+    NO_AUTH -> "NO_AUTH"
+    HAS_AUTH -> "HAS_AUTH"
+    NO_ENTITY -> "NO_ENTITY"
+  smpP =
+    A.takeTill (== ' ') >>= \case
+      "UNKNOWN" -> pure UNKNOWN
+      "SYNTAX" -> pure SYNTAX
+      "NO_AUTH" -> pure NO_AUTH
+      "HAS_AUTH" -> pure HAS_AUTH
+      "NO_ENTITY" -> pure NO_ENTITY
+      "NO_QUEUE" -> pure NO_ENTITY
+      _ -> fail "bad command error type"
+
+-- | Send signed SMP transmission to TCP transport.
+tPut :: Transport c => THandle c -> SentRawTransmission -> IO (Either TransportError ())
+tPut th (sig, t) = tPutBlock th $ smpEncode (C.signatureBytes sig) <> t
+
+encodeTransmission :: ProtocolEncoding c => ByteString -> Transmission c -> ByteString
+encodeTransmission sessionId (CorrId corrId, queueId, command) =
+  smpEncode (sessionId, corrId, queueId) <> encodeProtocol command
+
+-- | Receive and parse transmission from the TCP transport (ignoring any trailing padding).
+tGetParse :: Transport c => THandle c -> IO (Either TransportError RawTransmission)
+tGetParse th = (parse transmissionP TEBadBlock =<<) <$> tGetBlock th
+
+-- | Receive client and server transmissions (determined by `cmd` type).
+tGet :: forall cmd c m. (ProtocolEncoding cmd, Transport c, MonadIO m) => THandle c -> m (SignedTransmission cmd)
+tGet th@THandle {sessionId} = liftIO (tGetParse th) >>= decodeParseValidate
+  where
+    decodeParseValidate :: Either TransportError RawTransmission -> m (SignedTransmission cmd)
+    decodeParseValidate = \case
+      Right RawTransmission {signature, signed, sessId, corrId, entityId, command}
+        | sessId == sessionId ->
+          let decodedTransmission = (,corrId,entityId,command) <$> C.decodeSignature signature
+           in either (const $ tError corrId) (tParseValidate signed) decodedTransmission
+        | otherwise -> pure (Nothing, "", (CorrId corrId, "", Left SESSION))
+      Left _ -> tError ""
+
+    tError :: ByteString -> m (SignedTransmission cmd)
+    tError corrId = pure (Nothing, "", (CorrId corrId, "", Left BLOCK))
+
+    tParseValidate :: ByteString -> SignedRawTransmission -> m (SignedTransmission cmd)
+    tParseValidate signed t@(sig, corrId, entityId, command) = do
+      let cmd = parseProtocol command >>= checkCredentials t
+      pure (sig, signed, (CorrId corrId, entityId, cmd))

src/Simplex/Messaging/Server.hs

@@ -0,0 +1,568 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE NumericUnderscores #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+
+-- |
+-- Module      : Simplex.Messaging.Server
+-- Copyright   : (c) simplex.chat
+-- License     : AGPL-3
+--
+-- Maintainer  : chat@simplex.chat
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- This module defines SMP protocol server with in-memory persistence
+-- and optional append only log of SMP queue records.
+--
+-- See https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md
+module Simplex.Messaging.Server
+  ( runSMPServer,
+    runSMPServerBlocking,
+    disconnectTransport,
+    verifyCmdSignature,
+    dummyVerifyCmd,
+  )
+where
+
+import Control.Logger.Simple
+import Control.Monad
+import Control.Monad.Except
+import Control.Monad.IO.Unlift
+import Control.Monad.Reader
+import Crypto.Random
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as B
+import Data.Functor (($>))
+import Data.List (intercalate)
+import qualified Data.Map.Strict as M
+import Data.Maybe (isNothing)
+import qualified Data.Set as S
+import qualified Data.Text as T
+import Data.Time.Clock (UTCTime (..), diffTimeToPicoseconds, getCurrentTime)
+import Data.Time.Clock.System (SystemTime (..), getSystemTime)
+import Data.Type.Equality
+import Network.Socket (ServiceName)
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding.String
+import Simplex.Messaging.Protocol
+import Simplex.Messaging.Server.Env.STM
+import Simplex.Messaging.Server.Expiration
+import Simplex.Messaging.Server.MsgStore
+import Simplex.Messaging.Server.MsgStore.STM (MsgQueue)
+import Simplex.Messaging.Server.QueueStore
+import Simplex.Messaging.Server.QueueStore.STM (QueueStore)
+import Simplex.Messaging.Server.StoreLog
+import Simplex.Messaging.TMap (TMap)
+import qualified Simplex.Messaging.TMap as TM
+import Simplex.Messaging.Transport
+import Simplex.Messaging.Transport.Server
+import Simplex.Messaging.Util
+import System.Mem.Weak (deRefWeak)
+import UnliftIO.Concurrent
+import UnliftIO.Directory (doesFileExist, renameFile)
+import UnliftIO.Exception
+import UnliftIO.IO
+import UnliftIO.STM
+
+-- | Runs an SMP server using passed configuration.
+--
+-- See a full server here: https://github.com/simplex-chat/simplexmq/blob/master/apps/smp-server/Main.hs
+runSMPServer :: (MonadRandom m, MonadUnliftIO m) => ServerConfig -> m ()
+runSMPServer cfg = do
+  started <- newEmptyTMVarIO
+  runSMPServerBlocking started cfg
+
+-- | Runs an SMP server using passed configuration with signalling.
+--
+-- This function uses passed TMVar to signal when the server is ready to accept TCP requests (True)
+-- and when it is disconnected from the TCP socket once the server thread is killed (False).
+runSMPServerBlocking :: (MonadRandom m, MonadUnliftIO m) => TMVar Bool -> ServerConfig -> m ()
+runSMPServerBlocking started cfg = newEnv cfg >>= runReaderT (smpServer started)
+
+smpServer :: forall m. (MonadUnliftIO m, MonadReader Env m) => TMVar Bool -> m ()
+smpServer started = do
+  s <- asks server
+  cfg@ServerConfig {transports} <- asks config
+  restoreServerMessages
+  raceAny_
+    ( serverThread s subscribedQ subscribers subscriptions cancelSub :
+      serverThread s ntfSubscribedQ notifiers ntfSubscriptions (\_ -> pure ()) :
+      map runServer transports <> expireMessagesThread_ cfg <> serverStatsThread_ cfg
+    )
+    `finally` (withLog closeStoreLog >> saveServerMessages)
+  where
+    runServer :: (ServiceName, ATransport) -> m ()
+    runServer (tcpPort, ATransport t) = do
+      serverParams <- asks tlsServerParams
+      runTransportServer started tcpPort serverParams (runClient t)
+
+    serverThread ::
+      forall s.
+      Server ->
+      (Server -> TBQueue (QueueId, Client)) ->
+      (Server -> TMap QueueId Client) ->
+      (Client -> TMap QueueId s) ->
+      (s -> m ()) ->
+      m ()
+    serverThread s subQ subs clientSubs unsub = forever $ do
+      atomically updateSubscribers
+        $>>= endPreviousSubscriptions
+        >>= mapM_ unsub
+      where
+        updateSubscribers :: STM (Maybe (QueueId, Client))
+        updateSubscribers = do
+          (qId, clnt) <- readTBQueue $ subQ s
+          let clientToBeNotified = \c' ->
+                if sameClientSession clnt c'
+                  then pure Nothing
+                  else do
+                    yes <- readTVar $ connected c'
+                    pure $ if yes then Just (qId, c') else Nothing
+          TM.lookupInsert qId clnt (subs s) $>>= clientToBeNotified
+        endPreviousSubscriptions :: (QueueId, Client) -> m (Maybe s)
+        endPreviousSubscriptions (qId, c) = do
+          void . forkIO . atomically $
+            writeTBQueue (sndQ c) (CorrId "", qId, END)
+          atomically $ TM.lookupDelete qId (clientSubs c)
+
+    expireMessagesThread_ :: ServerConfig -> [m ()]
+    expireMessagesThread_ ServerConfig {messageExpiration = Just msgExp} = [expireMessages msgExp]
+    expireMessagesThread_ _ = []
+
+    expireMessages :: ExpirationConfig -> m ()
+    expireMessages expCfg = do
+      ms <- asks msgStore
+      quota <- asks $ msgQueueQuota . config
+      let interval = checkInterval expCfg * 1000000
+      forever $ do
+        threadDelay interval
+        old <- liftIO $ expireBeforeEpoch expCfg
+        rIds <- M.keysSet <$> readTVarIO ms
+        forM_ rIds $ \rId ->
+          atomically (getMsgQueue ms rId quota)
+            >>= atomically . (`deleteExpiredMsgs` old)
+
+    serverStatsThread_ :: ServerConfig -> [m ()]
+    serverStatsThread_ ServerConfig {logStatsInterval = Just interval, logStatsStartTime} =
+      [logServerStats logStatsStartTime interval]
+    serverStatsThread_ _ = []
+
+    logServerStats :: Int -> Int -> m ()
+    logServerStats startAt logInterval = do
+      initialDelay <- (startAt -) . fromIntegral . (`div` 1000000_000000) . diffTimeToPicoseconds . utctDayTime <$> liftIO getCurrentTime
+      logInfo $ "fromTime,qCreated,qSecured,qDeleted,msgSent,msgRecv,msgQueues"
+      threadDelay $ 1000000 * (initialDelay + if initialDelay < 0 then 86400 else 0)
+      ServerStats {fromTime, qCreated, qSecured, qDeleted, msgSent, msgRecv, msgQueues} <- asks serverStats
+      let interval = 1000000 * logInterval
+      forever $ do
+        ts <- liftIO getCurrentTime
+        fromTime' <- atomically $ swapTVar fromTime ts
+        qCreated' <- atomically $ swapTVar qCreated 0
+        qSecured' <- atomically $ swapTVar qSecured 0
+        qDeleted' <- atomically $ swapTVar qDeleted 0
+        msgSent' <- atomically $ swapTVar msgSent 0
+        msgRecv' <- atomically $ swapTVar msgRecv 0
+        msgQueues' <- atomically $ S.size <$> swapTVar msgQueues S.empty
+        logInfo . T.pack $ intercalate "," [show fromTime', show qCreated', show qSecured', show qDeleted', show msgSent', show msgRecv', show msgQueues']
+        threadDelay interval
+
+    runClient :: Transport c => TProxy c -> c -> m ()
+    runClient _ h = do
+      kh <- asks serverIdentity
+      liftIO (runExceptT $ smpServerHandshake h kh) >>= \case
+        Right th -> runClientTransport th
+        Left _ -> pure ()
+
+runClientTransport :: (Transport c, MonadUnliftIO m, MonadReader Env m) => THandle c -> m ()
+runClientTransport th@THandle {sessionId} = do
+  q <- asks $ tbqSize . config
+  ts <- liftIO getSystemTime
+  c <- atomically $ newClient q sessionId ts
+  s <- asks server
+  expCfg <- asks $ inactiveClientExpiration . config
+  raceAny_ ([send th c, client c s, receive th c] <> disconnectThread_ c expCfg)
+    `finally` clientDisconnected c
+  where
+    disconnectThread_ c (Just expCfg) = [disconnectTransport th c activeAt expCfg]
+    disconnectThread_ _ _ = []
+
+clientDisconnected :: (MonadUnliftIO m, MonadReader Env m) => Client -> m ()
+clientDisconnected c@Client {subscriptions, connected} = do
+  atomically $ writeTVar connected False
+  subs <- readTVarIO subscriptions
+  mapM_ cancelSub subs
+  atomically $ writeTVar subscriptions M.empty
+  cs <- asks $ subscribers . server
+  atomically . mapM_ (\rId -> TM.update deleteCurrentClient rId cs) $ M.keys subs
+  where
+    deleteCurrentClient :: Client -> Maybe Client
+    deleteCurrentClient c'
+      | sameClientSession c c' = Nothing
+      | otherwise = Just c'
+
+sameClientSession :: Client -> Client -> Bool
+sameClientSession Client {sessionId} Client {sessionId = s'} = sessionId == s'
+
+cancelSub :: MonadUnliftIO m => Sub -> m ()
+cancelSub = \case
+  Sub {subThread = SubThread t} -> liftIO $ deRefWeak t >>= mapM_ killThread
+  _ -> return ()
+
+receive :: (Transport c, MonadUnliftIO m, MonadReader Env m) => THandle c -> Client -> m ()
+receive th Client {rcvQ, sndQ, activeAt} = forever $ do
+  (sig, signed, (corrId, queueId, cmdOrError)) <- tGet th
+  atomically . writeTVar activeAt =<< liftIO getSystemTime
+  case cmdOrError of
+    Left e -> write sndQ (corrId, queueId, ERR e)
+    Right cmd -> do
+      verified <- verifyTransmission sig signed queueId cmd
+      if verified
+        then write rcvQ (corrId, queueId, cmd)
+        else write sndQ (corrId, queueId, ERR AUTH)
+  where
+    write q t = atomically $ writeTBQueue q t
+
+send :: (Transport c, MonadUnliftIO m) => THandle c -> Client -> m ()
+send h Client {sndQ, sessionId, activeAt} = forever $ do
+  t <- atomically $ readTBQueue sndQ
+  -- TODO the line below can return Left, but we ignore it and do not disconnect the client
+  void . liftIO $ tPut h (Nothing, encodeTransmission sessionId t)
+  atomically . writeTVar activeAt =<< liftIO getSystemTime
+
+disconnectTransport :: (Transport c, MonadUnliftIO m) => THandle c -> client -> (client -> TVar SystemTime) -> ExpirationConfig -> m ()
+disconnectTransport THandle {connection} c activeAt expCfg = do
+  let interval = checkInterval expCfg * 1000000
+  forever . liftIO $ do
+    threadDelay interval
+    old <- expireBeforeEpoch expCfg
+    ts <- readTVarIO $ activeAt c
+    when (systemSeconds ts < old) $ closeConnection connection
+
+verifyTransmission ::
+  forall m. (MonadUnliftIO m, MonadReader Env m) => Maybe C.ASignature -> ByteString -> QueueId -> Cmd -> m Bool
+verifyTransmission sig_ signed queueId cmd = do
+  case cmd of
+    Cmd SRecipient (NEW k _) -> pure $ verifyCmdSignature sig_ signed k
+    Cmd SRecipient _ -> verifyCmd SRecipient $ verifyCmdSignature sig_ signed . recipientKey
+    Cmd SSender (SEND _) -> verifyCmd SSender $ verifyMaybe . senderKey
+    Cmd SSender PING -> pure True
+    Cmd SNotifier NSUB -> verifyCmd SNotifier $ verifyMaybe . fmap snd . notifier
+  where
+    verifyCmd :: SParty p -> (QueueRec -> Bool) -> m Bool
+    verifyCmd party f = do
+      st <- asks queueStore
+      q <- atomically $ getQueue st party queueId
+      pure $ either (const $ maybe False (dummyVerifyCmd signed) sig_ `seq` False) f q
+    verifyMaybe :: Maybe C.APublicVerifyKey -> Bool
+    verifyMaybe = maybe (isNothing sig_) $ verifyCmdSignature sig_ signed
+
+verifyCmdSignature :: Maybe C.ASignature -> ByteString -> C.APublicVerifyKey -> Bool
+verifyCmdSignature sig_ signed key = maybe False (verify key) sig_
+  where
+    verify :: C.APublicVerifyKey -> C.ASignature -> Bool
+    verify (C.APublicVerifyKey a k) sig@(C.ASignature a' s) =
+      case (testEquality a a', C.signatureSize k == C.signatureSize s) of
+        (Just Refl, True) -> C.verify' k s signed
+        _ -> dummyVerifyCmd signed sig `seq` False
+
+dummyVerifyCmd :: ByteString -> C.ASignature -> Bool
+dummyVerifyCmd signed (C.ASignature _ s) = C.verify' (dummyPublicKey s) s signed
+
+-- These dummy keys are used with `dummyVerify` function to mitigate timing attacks
+-- by having the same time of the response whether a queue exists or nor, for all valid key/signature sizes
+dummyPublicKey :: C.Signature a -> C.PublicKey a
+dummyPublicKey = \case
+  C.SignatureEd25519 _ -> dummyKeyEd25519
+  C.SignatureEd448 _ -> dummyKeyEd448
+
+dummyKeyEd25519 :: C.PublicKey 'C.Ed25519
+dummyKeyEd25519 = "MCowBQYDK2VwAyEA139Oqs4QgpqbAmB0o7rZf6T19ryl7E65k4AYe0kE3Qs="
+
+dummyKeyEd448 :: C.PublicKey 'C.Ed448
+dummyKeyEd448 = "MEMwBQYDK2VxAzoA6ibQc9XpkSLtwrf7PLvp81qW/etiumckVFImCMRdftcG/XopbOSaq9qyLhrgJWKOLyNrQPNVvpMA"
+
+client :: forall m. (MonadUnliftIO m, MonadReader Env m) => Client -> Server -> m ()
+client clnt@Client {subscriptions, ntfSubscriptions, rcvQ, sndQ} Server {subscribedQ, ntfSubscribedQ, notifiers} =
+  forever $
+    atomically (readTBQueue rcvQ)
+      >>= processCommand
+      >>= atomically . writeTBQueue sndQ
+  where
+    processCommand :: Transmission Cmd -> m (Transmission BrokerMsg)
+    processCommand (corrId, queueId, cmd) = do
+      st <- asks queueStore
+      case cmd of
+        Cmd SSender command ->
+          case command of
+            SEND msgBody -> sendMessage st msgBody
+            PING -> pure (corrId, "", PONG)
+        Cmd SNotifier NSUB -> subscribeNotifications
+        Cmd SRecipient command ->
+          case command of
+            NEW rKey dhKey ->
+              ifM
+                (asks $ allowNewQueues . config)
+                (createQueue st rKey dhKey)
+                (pure (corrId, queueId, ERR AUTH))
+            SUB -> subscribeQueue queueId
+            ACK -> acknowledgeMsg
+            KEY sKey -> secureQueue_ st sKey
+            NKEY nKey -> addQueueNotifier_ st nKey
+            OFF -> suspendQueue_ st
+            DEL -> delQueueAndMsgs st
+      where
+        createQueue :: QueueStore -> RcvPublicVerifyKey -> RcvPublicDhKey -> m (Transmission BrokerMsg)
+        createQueue st recipientKey dhKey = do
+          (rcvPublicDhKey, privDhKey) <- liftIO C.generateKeyPair'
+          let rcvDhSecret = C.dh' dhKey privDhKey
+              qik (rcvId, sndId) = QIK {rcvId, sndId, rcvPublicDhKey}
+              qRec (recipientId, senderId) =
+                QueueRec
+                  { recipientId,
+                    senderId,
+                    recipientKey,
+                    rcvDhSecret,
+                    senderKey = Nothing,
+                    notifier = Nothing,
+                    status = QueueActive
+                  }
+          (corrId,queueId,) <$> addQueueRetry 3 qik qRec
+          where
+            addQueueRetry ::
+              Int -> ((RecipientId, SenderId) -> QueueIdsKeys) -> ((RecipientId, SenderId) -> QueueRec) -> m BrokerMsg
+            addQueueRetry 0 _ _ = pure $ ERR INTERNAL
+            addQueueRetry n qik qRec = do
+              ids@(rId, _) <- getIds
+              -- create QueueRec record with these ids and keys
+              atomically (addQueue st $ qRec ids) >>= \case
+                Left DUPLICATE_ -> addQueueRetry (n - 1) qik qRec
+                Left e -> pure $ ERR e
+                Right _ -> do
+                  withLog (`logCreateById` rId)
+                  stats <- asks serverStats
+                  atomically $ modifyTVar (qCreated stats) (+ 1)
+                  subscribeQueue rId $> IDS (qik ids)
+
+            logCreateById :: StoreLog 'WriteMode -> RecipientId -> IO ()
+            logCreateById s rId =
+              atomically (getQueue st SRecipient rId) >>= \case
+                Right q -> logCreateQueue s q
+                _ -> pure ()
+
+            getIds :: m (RecipientId, SenderId)
+            getIds = do
+              n <- asks $ queueIdBytes . config
+              liftM2 (,) (randomId n) (randomId n)
+
+        secureQueue_ :: QueueStore -> SndPublicVerifyKey -> m (Transmission BrokerMsg)
+        secureQueue_ st sKey = do
+          withLog $ \s -> logSecureQueue s queueId sKey
+          stats <- asks serverStats
+          atomically $ modifyTVar (qSecured stats) (+ 1)
+          atomically $ (corrId,queueId,) . either ERR (const OK) <$> secureQueue st queueId sKey
+
+        addQueueNotifier_ :: QueueStore -> NtfPublicVerifyKey -> m (Transmission BrokerMsg)
+        addQueueNotifier_ st nKey = (corrId,queueId,) <$> addNotifierRetry 3
+          where
+            addNotifierRetry :: Int -> m BrokerMsg
+            addNotifierRetry 0 = pure $ ERR INTERNAL
+            addNotifierRetry n = do
+              nId <- randomId =<< asks (queueIdBytes . config)
+              atomically (addQueueNotifier st queueId nId nKey) >>= \case
+                Left DUPLICATE_ -> addNotifierRetry $ n - 1
+                Left e -> pure $ ERR e
+                Right _ -> do
+                  withLog $ \s -> logAddNotifier s queueId nId nKey
+                  pure $ NID nId
+
+        suspendQueue_ :: QueueStore -> m (Transmission BrokerMsg)
+        suspendQueue_ st = do
+          withLog (`logDeleteQueue` queueId)
+          okResp <$> atomically (suspendQueue st queueId)
+
+        subscribeQueue :: RecipientId -> m (Transmission BrokerMsg)
+        subscribeQueue rId =
+          atomically (getSubscription rId) >>= deliverMessage tryPeekMsg rId
+
+        getSubscription :: RecipientId -> STM Sub
+        getSubscription rId = do
+          TM.lookup rId subscriptions >>= \case
+            Just s -> tryTakeTMVar (delivered s) $> s
+            Nothing -> do
+              writeTBQueue subscribedQ (rId, clnt)
+              s <- newSubscription
+              TM.insert rId s subscriptions
+              return s
+
+        subscribeNotifications :: m (Transmission BrokerMsg)
+        subscribeNotifications = atomically $ do
+          unlessM (TM.member queueId ntfSubscriptions) $ do
+            writeTBQueue ntfSubscribedQ (queueId, clnt)
+            TM.insert queueId () ntfSubscriptions
+          pure ok
+
+        acknowledgeMsg :: m (Transmission BrokerMsg)
+        acknowledgeMsg =
+          atomically (withSub queueId $ \s -> const s <$$> tryTakeTMVar (delivered s))
+            >>= \case
+              Just (Just s) -> do
+                stats <- asks serverStats
+                atomically $ modifyTVar (msgRecv stats) (+ 1)
+                atomically $ modifyTVar (msgQueues stats) (S.insert queueId)
+                deliverMessage tryDelPeekMsg queueId s
+              _ -> return $ err NO_MSG
+
+        withSub :: RecipientId -> (Sub -> STM a) -> STM (Maybe a)
+        withSub rId f = mapM f =<< TM.lookup rId subscriptions
+
+        sendMessage :: QueueStore -> MsgBody -> m (Transmission BrokerMsg)
+        sendMessage st msgBody
+          | B.length msgBody > maxMessageLength = pure $ err LARGE_MSG
+          | otherwise = do
+            qr <- atomically $ getQueue st SSender queueId
+            either (return . err) storeMessage qr
+          where
+            storeMessage :: QueueRec -> m (Transmission BrokerMsg)
+            storeMessage qr = case status qr of
+              QueueOff -> return $ err AUTH
+              QueueActive ->
+                mkMessage >>= \case
+                  Left _ -> pure $ err LARGE_MSG
+                  Right msg -> do
+                    ms <- asks msgStore
+                    ServerConfig {messageExpiration, msgQueueQuota} <- asks config
+                    old <- liftIO $ mapM expireBeforeEpoch messageExpiration
+                    resp@(_, _, sent) <- atomically $ do
+                      q <- getMsgQueue ms (recipientId qr) msgQueueQuota
+                      mapM_ (deleteExpiredMsgs q) old
+                      ifM (isFull q) (pure $ err QUOTA) $ do
+                        trySendNotification
+                        writeMsg q msg
+                        pure ok
+                    when (sent == OK) $ do
+                      stats <- asks serverStats
+                      atomically $ modifyTVar (msgSent stats) (+ 1)
+                      atomically $ modifyTVar (msgQueues stats) (S.insert $ recipientId qr)
+                    pure resp
+              where
+                mkMessage :: m (Either C.CryptoError Message)
+                mkMessage = do
+                  msgId <- randomId =<< asks (msgIdBytes . config)
+                  ts <- liftIO getSystemTime
+                  let c = C.cbEncrypt (rcvDhSecret qr) (C.cbNonce msgId) msgBody (maxMessageLength + 2)
+                  pure $ Message msgId ts <$> c
+
+                trySendNotification :: STM ()
+                trySendNotification =
+                  forM_ (notifier qr) $ \(nId, _) ->
+                    mapM_ (writeNtf nId) =<< TM.lookup nId notifiers
+
+                writeNtf :: NotifierId -> Client -> STM ()
+                writeNtf nId Client {sndQ = q} =
+                  unlessM (isFullTBQueue sndQ) $
+                    writeTBQueue q (CorrId "", nId, NMSG)
+
+        deliverMessage :: (MsgQueue -> STM (Maybe Message)) -> RecipientId -> Sub -> m (Transmission BrokerMsg)
+        deliverMessage tryPeek rId = \case
+          Sub {subThread = NoSub} -> do
+            ms <- asks msgStore
+            quota <- asks $ msgQueueQuota . config
+            q <- atomically $ getMsgQueue ms rId quota
+            atomically (tryPeek q) >>= \case
+              Nothing -> forkSub q $> ok
+              Just msg -> atomically setDelivered $> (corrId, rId, msgCmd msg)
+          _ -> pure ok
+          where
+            forkSub :: MsgQueue -> m ()
+            forkSub q = do
+              atomically . setSub $ \s -> s {subThread = SubPending}
+              t <- mkWeakThreadId =<< forkIO (subscriber q)
+              atomically . setSub $ \case
+                s@Sub {subThread = SubPending} -> s {subThread = SubThread t}
+                s -> s
+
+            subscriber :: MsgQueue -> m ()
+            subscriber q = atomically $ do
+              msg <- peekMsg q
+              writeTBQueue sndQ (CorrId "", rId, msgCmd msg)
+              setSub (\s -> s {subThread = NoSub})
+              void setDelivered
+
+            setSub :: (Sub -> Sub) -> STM ()
+            setSub f = TM.adjust f rId subscriptions
+
+            setDelivered :: STM (Maybe Bool)
+            setDelivered = withSub rId $ \s -> tryPutTMVar (delivered s) ()
+
+            msgCmd :: Message -> BrokerMsg
+            msgCmd Message {msgId, ts, msgBody} = MSG msgId ts msgBody
+
+        delQueueAndMsgs :: QueueStore -> m (Transmission BrokerMsg)
+        delQueueAndMsgs st = do
+          withLog (`logDeleteQueue` queueId)
+          ms <- asks msgStore
+          stats <- asks serverStats
+          atomically $ modifyTVar (qDeleted stats) (+ 1)
+          atomically $
+            deleteQueue st queueId >>= \case
+              Left e -> pure $ err e
+              Right _ -> delMsgQueue ms queueId $> ok
+
+        ok :: Transmission BrokerMsg
+        ok = (corrId, queueId, OK)
+
+        err :: ErrorType -> Transmission BrokerMsg
+        err e = (corrId, queueId, ERR e)
+
+        okResp :: Either ErrorType () -> Transmission BrokerMsg
+        okResp = either err $ const ok
+
+withLog :: (MonadUnliftIO m, MonadReader Env m) => (StoreLog 'WriteMode -> IO a) -> m ()
+withLog action = do
+  env <- ask
+  liftIO . mapM_ action $ storeLog (env :: Env)
+
+randomId :: (MonadUnliftIO m, MonadReader Env m) => Int -> m ByteString
+randomId n = do
+  gVar <- asks idsDrg
+  atomically (C.pseudoRandomBytes n gVar)
+
+saveServerMessages :: forall m. (MonadUnliftIO m, MonadReader Env m) => m ()
+saveServerMessages = asks (storeMsgsFile . config) >>= mapM_ saveMessages
+  where
+    saveMessages f = do
+      liftIO $ putStrLn $ "saving messages to file " <> f
+      ms <- asks msgStore
+      liftIO . withFile f WriteMode $ \h ->
+        readTVarIO ms >>= mapM_ (saveQueueMsgs ms h) . M.keys
+      where
+        saveQueueMsgs ms h rId =
+          atomically (flushMsgQueue ms rId)
+            >>= mapM_ (B.hPutStrLn h . strEncode . MsgLogRecord rId)
+
+restoreServerMessages :: forall m. (MonadUnliftIO m, MonadReader Env m) => m ()
+restoreServerMessages = asks (storeMsgsFile . config) >>= mapM_ restoreMessages
+  where
+    restoreMessages f = whenM (doesFileExist f) $ do
+      liftIO $ putStrLn $ "restoring messages from file " <> f
+      ms <- asks msgStore
+      quota <- asks $ msgQueueQuota . config
+      liftIO $ mapM_ (restoreMsg ms quota) . B.lines =<< B.readFile f
+      renameFile f $ f <> ".bak"
+      where
+        restoreMsg ms quota s = case strDecode s of
+          Left e -> B.putStrLn $ "message parsing error (" <> B.pack e <> "): " <> B.take 100 s
+          Right (MsgLogRecord rId msg) -> do
+            full <- atomically $ do
+              q <- getMsgQueue ms rId quota
+              ifM (isFull q) (pure True) (writeMsg q msg $> False)
+            when full . B.putStrLn $ "message queue " <> strEncode rId <> " is full, message not restored: " <> strEncode (msgId msg)