From 4224ddff0bd96453941a8afccb7ca381d9df680d Mon Sep 17 00:00:00 2001 From: liamcottle Date: Sun, 8 Feb 2026 14:05:37 +1300 Subject: [PATCH] refactor packet format docs --- docs/index.md | 2 +- docs/packet_format.md | 120 +++++++++++++++++++++++++++++++++++++++ docs/packet_structure.md | 60 -------------------- docs/payloads.md | 17 +++--- 4 files changed, 130 insertions(+), 69 deletions(-) create mode 100644 docs/packet_format.md delete mode 100644 docs/packet_structure.md diff --git a/docs/index.md b/docs/index.md index f4394f75..9460a00c 100644 --- a/docs/index.md +++ b/docs/index.md @@ -7,7 +7,7 @@ Below are a few quick start guides. - [Frequently Asked Questions](./faq.md) - [CLI Commands](./cli_commands.md) - [Companion Protocol](./companion_protocol.md) -- [Packet Structure](./packet_structure.md) +- [Packet Format](./packet_format.md) - [QR Codes](./qr_codes.md) If you find a mistake in any of our documentation, or find something is missing, please feel free to open a pull request for us to review. diff --git a/docs/packet_format.md b/docs/packet_format.md new file mode 100644 index 00000000..50f9c01a --- /dev/null +++ b/docs/packet_format.md @@ -0,0 +1,120 @@ +# Packet Format + +This document describes the MeshCore packet format. + +- `0xYY` indicates `YY` in hex notation. +- `0bYY` indicates `YY` in binary notation. +- Bit 0 indicates the bit furthest to the right: `0000000X` +- Bit 7 indicates the bit furthest to the left: `X0000000` + +## Version 1 Packet Format + +This is the protocol level packet structure used in MeshCore firmware v1.12.0 + +``` +[header][transport_codes(optional)][path_length][path][payload] +``` + +- [header](#header-format) - 1 byte + - 8-bit Format: `0bVVPPPPRR` - `V=Version` - `P=PayloadType` - `R=RouteType` + - Bits 0-1 - 2-bits - [Route Type](#route-types) + - `0x00`/`0b00` - `ROUTE_TYPE_TRANSPORT_FLOOD` - Flood Routing + Transport Codes + - `0x01`/`0b01` - `ROUTE_TYPE_FLOOD` - Flood Routing + - `0x02`/`0b10` - `ROUTE_TYPE_DIRECT` - Direct Routing + - `0x03`/`0b11` - `ROUTE_TYPE_TRANSPORT_DIRECT` - Direct Routing + Transport Codes + - Bits 2-5 - 4-bits - [Payload Type](#payload-types) + - `0x00`/`0b0000` - `PAYLOAD_TYPE_REQ` - Request (destination/source hashes + MAC) + - `0x01`/`0b0001` - `PAYLOAD_TYPE_RESPONSE` - Response to `REQ` or `ANON_REQ` + - `0x02`/`0b0010` - `PAYLOAD_TYPE_TXT_MSG` - Plain text message + - `0x03`/`0b0011` - `PAYLOAD_TYPE_ACK` - Acknowledgment + - `0x04`/`0b0100` - `PAYLOAD_TYPE_ADVERT` - Node advertisement + - `0x05`/`0b0101` - `PAYLOAD_TYPE_GRP_TXT` - Group text message (unverified) + - `0x06`/`0b0110` - `PAYLOAD_TYPE_GRP_DATA` - Group datagram (unverified) + - `0x07`/`0b0111` - `PAYLOAD_TYPE_ANON_REQ` - Anonymous request + - `0x08`/`0b1000` - `PAYLOAD_TYPE_PATH` - Returned path + - `0x09`/`0b1001` - `PAYLOAD_TYPE_TRACE` - Trace a path, collecting SNR for each hop + - `0x0A`/`0b1010` - `PAYLOAD_TYPE_MULTIPART` - Packet is part of a sequence of packets + - `0x0B`/`0b1011` - `PAYLOAD_TYPE_CONTROL` - Control packet data (unencrypted) + - `0x0C`/`0b1100` - reserved + - `0x0D`/`0b1101` - reserved + - `0x0E`/`0b1110` - reserved + - `0x0F`/`0b1111` - `PAYLOAD_TYPE_RAW_CUSTOM` - Custom packet (raw bytes, custom encryption) + - Bits 6-7 - 2-bits - [Payload Version](#payload-versions) + - `0x00`/`0b00` - v1 - 1-byte src/dest hashes, 2-byte MAC + - `0x01`/`0b01` - v2 - Future version (e.g., 2-byte hashes, 4-byte MAC) + - `0x02`/`0b10` - v3 - Future version + - `0x03`/`0b11` - v4 - Future version +- `transport_codes` - 4 bytes (optional) + - Only present for `ROUTE_TYPE_TRANSPORT_FLOOD` and `ROUTE_TYPE_TRANSPORT_DIRECT` + - `transport_code_1` - 2 bytes - `uint16_t` - calculated from region scope + - `transport_code_2` - 2 bytes - `uint16_t` - reserved +- `path_length` - 1 byte - Length of the path field in bytes +- `path` - size provided by `path_length` - Path to use for Direct Routing + - Up to a maximum of 64 bytes, defined by `MAX_PATH_SIZE` + - v1.12.0 firmware and older drops packets with `path_length` [larger than 64](https://github.com/meshcore-dev/MeshCore/blob/e812632235274ffd2382adf5354168aec765d416/src/Dispatcher.cpp#L144) +- `payload` - variable length - Payload Data + - Up to a maximum 184 bytes, defined by `MAX_PACKET_PAYLOAD` + - Generally this is the remainder of the raw packet data + - The firmware parses this data based on the provided Payload Type + - v1.12.0 firmware and older drops packets with `payload` sizes [larger than 184](https://github.com/meshcore-dev/MeshCore/blob/e812632235274ffd2382adf5354168aec765d416/src/Dispatcher.cpp#L152) + +### Packet Format + +| Field | Size (bytes) | Description | +|-----------------|----------------------------------|----------------------------------------------------------| +| header | 1 | Contains routing type, payload type, and payload version | +| transport_codes | 4 (optional) | 2x 16-bit transport codes (if ROUTE_TYPE_TRANSPORT_*) | +| path_length | 1 | Length of the path field in bytes | +| path | up to 64 (`MAX_PATH_SIZE`) | Stores the routing path if applicable | +| payload | up to 184 (`MAX_PACKET_PAYLOAD`) | Data for the provided Payload Type | + +> NOTE: see the [Payloads](./payloads.md) documentation for more information about the content of specific payload types. + +### Header Format + +Bit 0 means the lowest bit (1s place) + +| Bits | Mask | Field | Description | +|------|--------|-----------------|----------------------------------| +| 0-1 | `0x03` | Route Type | Flood, Direct, etc | +| 2-5 | `0x3C` | Payload Type | Request, Response, ACK, etc | +| 6-7 | `0xC0` | Payload Version | Versioning of the payload format | + +### Route Types + +| Value | Name | Description | +|--------|-------------------------------|----------------------------------| +| `0x00` | `ROUTE_TYPE_TRANSPORT_FLOOD` | Flood Routing + Transport Codes | +| `0x01` | `ROUTE_TYPE_FLOOD` | Flood Routing | +| `0x02` | `ROUTE_TYPE_DIRECT` | Direct Routing | +| `0x03` | `ROUTE_TYPE_TRANSPORT_DIRECT` | Direct Routing + Transport Codes | + +### Payload Types + +| Value | Name | Description | +|--------|---------------------------|----------------------------------------------| +| `0x00` | `PAYLOAD_TYPE_REQ` | Request (destination/source hashes + MAC) | +| `0x01` | `PAYLOAD_TYPE_RESPONSE` | Response to `REQ` or `ANON_REQ` | +| `0x02` | `PAYLOAD_TYPE_TXT_MSG` | Plain text message | +| `0x03` | `PAYLOAD_TYPE_ACK` | Acknowledgment | +| `0x04` | `PAYLOAD_TYPE_ADVERT` | Node advertisement | +| `0x05` | `PAYLOAD_TYPE_GRP_TXT` | Group text message (unverified) | +| `0x06` | `PAYLOAD_TYPE_GRP_DATA` | Group datagram (unverified) | +| `0x07` | `PAYLOAD_TYPE_ANON_REQ` | Anonymous request | +| `0x08` | `PAYLOAD_TYPE_PATH` | Returned path | +| `0x09` | `PAYLOAD_TYPE_TRACE` | Trace a path, collecting SNR for each hop | +| `0x0A` | `PAYLOAD_TYPE_MULTIPART` | Packet is part of a sequence of packets | +| `0x0B` | `PAYLOAD_TYPE_CONTROL` | Control packet data (unencrypted) | +| `0x0C` | reserved | reserved | +| `0x0D` | reserved | reserved | +| `0x0E` | reserved | reserved | +| `0x0F` | `PAYLOAD_TYPE_RAW_CUSTOM` | Custom packet (raw bytes, custom encryption) | + +### Payload Versions + +| Value | Version | Description | +|--------|---------|--------------------------------------------------| +| `0x00` | 1 | 1-byte src/dest hashes, 2-byte MAC | +| `0x01` | 2 | Future version (e.g., 2-byte hashes, 4-byte MAC) | +| `0x02` | 3 | Future version | +| `0x03` | 4 | Future version | diff --git a/docs/packet_structure.md b/docs/packet_structure.md deleted file mode 100644 index 92c410be..00000000 --- a/docs/packet_structure.md +++ /dev/null @@ -1,60 +0,0 @@ -# Packet Structure - -| Field | Size (bytes) | Description | -|-----------------|----------------------------------|-----------------------------------------------------------| -| header | 1 | Contains routing type, payload type, and payload version. | -| transport_codes | 4 (optional) | 2x 16-bit transport codes (if ROUTE_TYPE_TRANSPORT_*) | -| path_len | 1 | Length of the path field in bytes. | -| path | up to 64 (`MAX_PATH_SIZE`) | Stores the routing path if applicable. | -| payload | up to 184 (`MAX_PACKET_PAYLOAD`) | The actual data being transmitted. | - -Note: see the [payloads doc](./payloads.md) for more information about the content of payload. - -## Header Breakdown - -bit 0 means the lowest bit (1s place) - -| Bits | Mask | Field | Description | -|-------|--------|-----------------|-----------------------------------------------| -| 0-1 | `0x03` | Route Type | Flood, Direct, Reserved - see below. | -| 2-5 | `0x3C` | Payload Type | Request, Response, ACK, etc. - see below. | -| 6-7 | `0xC0` | Payload Version | Versioning of the payload format - see below. | - -## Route Type Values - -| Value | Name | Description | -|--------|-------------------------------|--------------------------------------| -| `0x00` | `ROUTE_TYPE_TRANSPORT_FLOOD` | Flood routing mode + transport codes | -| `0x01` | `ROUTE_TYPE_FLOOD` | Flood routing mode (builds up path). | -| `0x02` | `ROUTE_TYPE_DIRECT` | Direct route (path is supplied). | -| `0x03` | `ROUTE_TYPE_TRANSPORT_DIRECT` | direct route + transport codes | - -## Payload Type Values - -| Value | Name | Description | -|--------|---------------------------|-----------------------------------------------| -| `0x00` | `PAYLOAD_TYPE_REQ` | Request (destination/source hashes + MAC). | -| `0x01` | `PAYLOAD_TYPE_RESPONSE` | Response to REQ or ANON_REQ. | -| `0x02` | `PAYLOAD_TYPE_TXT_MSG` | Plain text message. | -| `0x03` | `PAYLOAD_TYPE_ACK` | Acknowledgment. | -| `0x04` | `PAYLOAD_TYPE_ADVERT` | Node advertisement. | -| `0x05` | `PAYLOAD_TYPE_GRP_TXT` | Group text message (unverified). | -| `0x06` | `PAYLOAD_TYPE_GRP_DATA` | Group datagram (unverified). | -| `0x07` | `PAYLOAD_TYPE_ANON_REQ` | Anonymous request. | -| `0x08` | `PAYLOAD_TYPE_PATH` | Returned path. | -| `0x09` | `PAYLOAD_TYPE_TRACE` | trace a path, collecting SNI for each hop. | -| `0x0A` | `PAYLOAD_TYPE_MULTIPART` | packet is part of a sequence of packets. | -| `0x0B` | `PAYLOAD_TYPE_CONTROL` | control packet data (unencrypted) | -| `0x0C` | . | reserved | -| `0x0D` | . | reserved | -| `0x0E` | . | reserved | -| `0x0F` | `PAYLOAD_TYPE_RAW_CUSTOM` | Custom packet (raw bytes, custom encryption). | - -## Payload Version Values - -| Value | Version | Description | -|--------|---------|---------------------------------------------------| -| `0x00` | 1 | 1-byte src/dest hashes, 2-byte MAC. | -| `0x01` | 2 | Future version (e.g., 2-byte hashes, 4-byte MAC). | -| `0x02` | 3 | Future version. | -| `0x03` | 4 | Future version. | diff --git a/docs/payloads.md b/docs/payloads.md index aaa84166..3648b655 100644 --- a/docs/payloads.md +++ b/docs/payloads.md @@ -1,5 +1,6 @@ -# Meshcore payloads -Inside of each [meshcore packet](./packet_structure.md) is a payload, identified by the payload type in the packet header. The types of payloads are: +# Payload Format + +Inside each [MeshCore Packet](./packet_format.md) is a payload, identified by the payload type in the packet header. The types of payloads are: * Node advertisement. * Acknowledgment. @@ -80,12 +81,12 @@ Returned path, request, response, and plain text messages are all formatted in t Returned path messages provide a description of the route a packet took from the original author. Receivers will send returned path messages to the author of the original message. -| Field | Size (bytes) | Description | -|-------------|--------------|----------------------------------------------------------------------------------------------| -| path length | 1 | length of next field | -| path | see above | a list of node hashes (one byte each) | -| extra type | 1 | extra, bundled payload type, eg., acknowledgement or response. Same values as in [packet structure](./packet_structure.md) | -| extra | rest of data | extra, bundled payload content, follows same format as main content defined by this document | +| Field | Size (bytes) | Description | +|-------------|--------------|----------------------------------------------------------------------------------------------------------------------| +| path length | 1 | length of next field | +| path | see above | a list of node hashes (one byte each) | +| extra type | 1 | extra, bundled payload type, eg., acknowledgement or response. Same values as in [Packet Format](./packet_format.md) | +| extra | rest of data | extra, bundled payload content, follows same format as main content defined by this document | ## Request