#	Component	What it does
1	reth + nimbus	self-hosted Ethereum node (`--minimal` — enough for the resolver's `eth_call` at chain head)
2	resolver	the REST resolver the smp-server's `[NAMES]` role queries (`snrc-resolve.py`)

Requirements

Docker + Compose v2.
≥ 300 GB NVMe SSD for reth --minimal (~260 GB on mainnet; TLC, not QLC — QLC stalls during sync) + 32 GB RAM, fast multi-core CPU.
~1 day for the initial reth sync. The resolver returns errors until reth has caught up — that's expected.
Firewall: open p2p ports 30303 (tcp/udp) and 9000 (tcp/udp).

1. Configure

Edit .env. The defaults work as they are; change them only if you need to:

NETWORK=mainnet                                               # default
TRUSTED_NODE_URL=https://mainnet-checkpoint-sync.attestant.io # default

Everything else (NAT) already has a working default in docker-compose.yml. Uncomment the hints in .env only if you need to change one.

2. Run

cd scripts/resolver
docker compose up -d
docker compose logs -f reth resolver

Compose starts the node before the resolver; depends_on takes care of that.

3. Wait for the node to sync

docker compose logs --tail=20 reth

This is the slow step: about a day on mainnet. Until reth has synced, the resolver returns 502.

Verify

Run the three checks below once the stack is up. The ones that need chain data pass only after the node has synced.

1. reth is reachable and reporting a block:

curl -s -X POST http://127.0.0.1:8545 \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}' | jq

2. resolver is healthy:

curl -s http://127.0.0.1:8000/health | jq
# → {"ok": true, "rpc": "http://reth:8545", "registries": {"testing": "0x…", "simplex": ""}}

3. resolver resolves a live name (foobar.testing is a populated test name):

curl -s http://127.0.0.1:8000/resolve/foobar.testing | jq
# → {"name":"foobar.testing","nickname":"Foo","simplexContact":["https://smp16.simplex.im/a#…"], … }

Point your smp-server at it: in its [NAMES] section set resolver_endpoint: http://127.0.0.1:8000 (no auth needed for loopback).

Ports (all loopback unless noted)

Service	Host	Purpose
reth JSON-RPC	`127.0.0.1:8545`	smp-server RPC
reth p2p	`:30303` tcp/udp	Ethereum sync (open on firewall)
nimbus p2p	`:9000` tcp/udp	beacon sync (open on firewall)
nimbus REST	`127.0.0.1:5052`	beacon API
resolver	`127.0.0.1:8000`	SNRC REST (`/v2/resolve`, `/resolve`, `/health`)

Caveats

All images track :latest (reth, nimbus). Each docker compose pull brings upstream fixes, so re-run the checks above afterwards.
All ports bind to loopback. Expose only what you put behind a TLS reverse proxy.

Teardown

docker compose down       # stop, keep all state
docker compose down -v    # also wipe volumes → full re-sync

down -v wipes the chain data (full re-sync on the next up).

Resolver API reference

You can also run the resolver (snrc-resolve.py, host 127.0.0.1:8000) on its own for local development, without Docker, using uv:

uv run scripts/resolver/service/snrc-resolve.py  # defaults to local reth + mainnet .testing

Response shape

{
  "name": "foobar.testing",
  "nickname": "Foo", "website": "https://foo.bar", "location": "",
  "simplexContact": ["https://smp16.simplex.im/a#…", "https://smp11…"],  // primary first, fallbacks after
  "simplexChannel": [],
  "eth": null, "btc": "bc1q…", "xmr": "4ANz…", "dot": "139G…",
  "owner": "0xd83b…", "resolver": "0x80fa…",
  "status": "registered",      // registered | grace | expired | unregistered | unknown
  "expires": 1780000000,       // Unix seconds; when the registration ends
  "graceEnds": 1787776000,     // expires + GRACE_PERIOD; last moment the owner can renew
  "reasonCode": null,          // set when the name is held back as well
  "reason": null               // set when the name is held back as well
}

simplexContact and simplexChannel are arrays, because a name can advertise several SMP servers; clients try them in order. On chain each one is a single text record with the entries joined by ;. The resolver splits that record, trims each entry and drops the empty ones. Addresses come back in each chain's usual format (EIP-55, bech32, SS58, Monero base58). Subnames work the same way (bar.foobar.testing).

Registration status and expiry

A response carries status, expires and graceEnds whenever the resolver read them, a successful resolve included, so a client that has just resolved a name already knows when it expires. Both timestamps are Unix seconds, and null when they could not be read.

`status`	Meaning
`registered`	live; `expires` is when that ends
`grace`	lapsed, but only the previous owner may renew it, until `graceEnds`
`expired`	lapsed and past grace; anyone may register it
`unregistered`	never registered, and free to take
`unknown`	no `SNRC_REGISTRAR_<TLD>` configured, so status could not be read

A reservation is orthogonal to the status: a name held back by the registry carries reasonCode and reason whether or not it is registered.

grace and expired are told apart by the registrar's own available(id) rule, expires + GRACE_PERIOD < now. GRACE_PERIOD is read from the contract rather than assumed, and now is the latest block's timestamp rather than the host clock, which the registrar compares against too, so a machine with a wrong clock cannot misreport a registration. That rule alone is not enough: it also holds for a name nobody ever registered (0 + GRACE_PERIOD < now), so a zero expiry is what separates never registered from registered and since released.

A subname reports the status of the 2LD above it, which is only as good as the name it sits under.

What a name costs

The controller's prices() names the price oracle, so no extra configuration is needed beyond SNRC_CONTROLLER_<TLD>. A SimplexPriceOracle exposes its curve through prices(), in US cents per year, which is the unit this API carries.

An ENS-shaped oracle exposes only price1Letter()..price6Letter(), in attoUSD per second, and charges a premium on a lapsed name that it does not expose. A quote from one is therefore only safe for a name that was never registered: an expired name gets no price rather than one below what the registrar charges.

Deployment constants - the grace period, the oracle and its curve - are cached for CONSTANTS_TTL (5 minutes), so a retune shows up within that. Per-name values are read on every query.

Set SNRC_CONTROLLER_<TLD> wherever SNRC_REGISTRAR_<TLD> is. Without a controller there is no oracle, so no name can be priced.

Why a name is reserved

A held-back name carries reasonCode, the controller's reason, and reason, an English sentence for a human reading this API. Clients should branch on reasonCode and word it themselves, in the user's language.

`reasonCode`	Meaning
`internal`	reserved for SimpleX
`trademark`	reserved to protect a trademark
`community`	reserved for the community
`unknown`	a reason added to the contract after this resolver; still reserved

These are SimplexController.Reason, where 0 means not reserved. A controller from before the enum stores a boolean, whose true decodes as 1, which is why 1 reads as internal, so nothing needs migrating.

Querying by labelhash

A client asking whether a name is free is usually about to register it, and whoever runs the resolver could register it first. To avoid that, send the keccak hash of the label in ENS's [<64 hex>] form instead of the label:

# instead of /resolve/acme.testing
curl -s "http://127.0.0.1:8000/resolve/[$(printf acme | keccak-256sum | cut -d' ' -f1)].testing"

namehash is keccak(parent || keccak(label)), so this reaches the same node and returns the same record. The registrar keys nameExpires and reservedNames on the labelhash too, so the status fields do not need the label either. The resolver learns the name only by guessing the label and hashing it.

Only the second-level label is a registry key, and it is decoded wherever it sits: sub.[<hash>].testing reaches the node sub.name.testing does. Subname labels stay text; a bracket label left of the 2LD is an ordinary label. Routers from v22 send every 2LD this way, so a registrable name normally never reaches this service.

Read the answer from status. A name is free on unregistered (404) and on expired (410). Every other status means somebody holds the name. A reasonCode means the registry will refuse it whatever the status says.

The hash must be keccak-256. openssl dgst -sha3-256 and sha3sum compute SHA3-256, a different function that returns 64 valid-looking hex characters pointing at the wrong node.

The resolver lowercases the query before matching, so uppercase hex works too. Clients that refuse raw brackets in a path can percent-encode them as %5B and %5D.

Brackets cannot collide with a real name: they are invalid in a normalised ENS name, and a [<64 hex>] label is 66 bytes against the registrar's maxLabelLength of 63. A plain 0x… label is not treated as a hash, since that is an ordinary, registrable name.

Only 2LDs can be queried this way, as only a 2LD can be raced for: subnames are created by the 2LD's owner. A bracket label in a subname is hashed as written, so it points at a node nobody can own. ENS tooling accepts the bracketed form at any depth; this resolver does not, on purpose.

This hides interest in a name and nothing else: the registration itself is public, and commit-reveal covers that step. A short or well-known label is easy to guess by hashing candidates, and the reveal publishes the labelhash, so an operator who logged the query can match it to the name afterwards.

Errors

Every non-2xx body carries two fields: error is a fixed code to branch on, and message is a sentence for a human. Match on error, never on message, which is free to change.

{"name": "nope.testing", "error": "unregistered",
 "message": "this name has never been registered",
 "status": "unregistered", "expires": null, "graceEnds": null}

The codes are tldNotConfigured, notFullyQualified, unregistered, expired, noSuchRoute and upstreamError. When the registration is what went wrong, error and status hold the same value, so one field is enough to read.

upstreamError says only which exception type the RPC call raised. The text goes to the resolver's log instead, because SNRC_RPC can carry a provider key and urlopen puts the URL it failed on into the message. It is also the answer when a registrar, controller or oracle address has no contract behind it: the empty reply is refused rather than read as zero, which would make every name look free.

Status codes

Status	Meaning
200	resolved (`status` is `registered` or `grace`, or `unknown` when no registrar is configured)
400	TLD not configured, or not a fully-qualified name
404	`unregistered`
410	`expired`: lapsed and past grace, so anyone may take it
502	upstream RPC error / reth not synced

Configuring addresses

The resolver reads three contracts, each configured per TLD.

The registry answers who owns a node, and /resolve reads the records from it. The registrar (ERC-721) holds nameExpires and GRACE_PERIOD, which is where every expiry field comes from. With no registrar for a TLD, /resolve still works and reports "status": "unknown". The controller holds reservedNames, which is where reasonCode comes from. With no controller a held-back name reads as not reserved, and no name can be priced.

All three default to the mainnet .testing deployment. .simplex is unset until it is deployed.

The controller default is the proxy, not SimplexControllerImpl. Storage lives in the proxy, so the implementation address answers nothing. The two deployment files use different names for that proxy: deployments.mainnet.testing.json records it under the ENS role name ETHRegistrarController, and verification.mainnet.testing.json calls it SimplexControllerProxy. Both are the same address, and it is the one used here.

To override any of them, set SNRC_REGISTRY_<TLD>, SNRC_REGISTRAR_<TLD> or SNRC_CONTROLLER_<TLD> on the resolver service in docker-compose.yml, or as env vars when you run the script directly.