A simple rendezvous + WebSocket signaling backend for WebRTC, designed for NoisyTransfer-style workflows. It mints short‑lived numeric codes for pairing and relays SDP/ICE between two peers over WebSockets.

Quick links

• GitHub repository: https://github.com/collapsinghierarchy/nt-backend-wrtc
• Related packages
  • CLI: https://www.npmjs.com/package/@noisytransfer/cli
  • noisyauth: https://www.npmjs.com/package/@noisytransfer/noisyauth
  • noisystream: https://www.npmjs.com/package/@noisytransfer/noisystream

Features

• Rendezvous service: short‑lived numerical 4‑digit codes, single‑use redeem, reclaimed on expiry.
• WebSocket signaling for SDP/ICE exchange between two sides (A/B).
• Mailbox frames: lightweight message queue (hello, send, delivered) in addition to offer/answer/ice; optional telemetry events.
• Rate limiting (per‑IP, fixed window) for HTTP and WS upgrades.
• Observability: Prometheus /metrics, /healthz (liveness), /readyz (readiness).
• TLS: optional, with sensible defaults.
• Janitor: background sweeper that prunes expired codes.

Quick start

1) Run with Docker Compose

docker compose up --build -d

Create a code:

curl -fsS -X POST http://localhost:1234/rendezvous/code
# -> {"code":"2802","appID":"...","expiresAt":"..."}

Redeem (once):

curl -fsS -X POST http://localhost:1234/rendezvous/redeem   -H 'content-type: application/json' -d '{"code":"2802"}'

2) WebSocket signaling (two terminals)

# Terminal A
wscat -c "ws://localhost:1234/ws?appID=<app-id>&side=A"

# Terminal B
wscat -c "ws://localhost:1234/ws?appID=<app-id>&side=B"

# Send from A, receive on B
> {"type":"offer","sdp":"..."}

Endpoints

Rendezvous (/rendezvous prefix)

• POST /code → {"code","appID","expiresAt"} — mint a fresh code.
• POST /redeem body: {"code":"NNNN"} → 200 {"appID","expiresAt"}; returns 410 Gone if used/expired/unknown.

WebSocket signaling

• GET /ws?appID=<uuid>&side=A|B — upgrade to WS.
• Accepted frames (JSON with type): offer, answer, ice, hello, send, delivered, telemetry.
  • Relay frames (offer/answer/ice) forward to the opposite side.
  • Mailbox: hello (trim), send (enqueue to to), delivered (ack up to seq).
  • telemetry (optional): e.g. { "type":"telemetry","event":"ice-connected" }.

Health & metrics

• GET /healthz → 200
• GET /readyz → 200 when ready
• GET /metrics → Prometheus text exposition

Configuration (environment variables)

Variable	Default	Description
HOST	0.0.0.0	Bind address for HTTP server
PORT	1234	HTTP/TLS port
ROOM_TTL	10m	Rendezvous code time‑to‑live
HEARTBEAT	20s	WS ping interval & read‑deadline base
WS_MAX_MSG	1048576	Max WS message bytes (read limit)
WS_READ_BUF	4096	Gorilla upgrader read buffer
WS_WRITE_BUF	4096	Gorilla upgrader write buffer
HTTP_RATE_PER_MIN	0	Per‑IP HTTP limit; 0 disables
WS_RATE_PER_MIN	0	Per‑IP WS upgrade limit; 0 disables
CORS_ORIGINS	(empty)	Comma‑separated allowlist of origins (prod)
DEV	true	If true, allow all origins
TLS_CERT_FILE	(empty)	Path to TLS cert (requires key too)
TLS_KEY_FILE	(empty)	Path to TLS key (requires cert too)
METRICS_ROUTE	/metrics	Prometheus endpoint path
LOG_LEVEL	info	Log level

Note: The server refuses to start if only one of TLS_CERT_FILE or TLS_KEY_FILE is set.

Build from source

go mod tidy
go build -trimpath -o ./bin/server ./cmd/server

Self‑signed TLS for local tests:

openssl req -x509 -newkey rsa:2048 -nodes -keyout server.key -out server.crt -days 365 -subj "/CN=localhost"
TLS_CERT_FILE=$PWD/server.crt TLS_KEY_FILE=$PWD/server.key ./bin/server

Tests

go clean -testcache
GOMAXPROCS=4 go test ./... -race -count=2

Integration in the NoisyTransfer stack

• Pairing flow: clients mint a short code via /rendezvous/code, redeem once via /rendezvous/redeem to get an appID, then connect both sides (A/B) to /ws and exchange offer/answer/ice.
• Use with the CLI (@noisytransfer/cli) or your own app built on @noisytransfer/noisyauth + @noisytransfer/noisystream or @noisytransfer/transport .
• Deploy behind a reverse proxy if you need TLS termination, sticky IP limits, or custom CORS.

License

Apache‑2.0

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If you’re building end‑to‑end flows, also see:

• CLI: @noisytransfer/cli — https://www.npmjs.com/package/@noisytransfer/cli
• Auth: @noisytransfer/noisyauth — https://www.npmjs.com/package/@noisytransfer/noisyauth
• PQ Encrypted Transport: @noisytransfer/noisystream — https://www.npmjs.com/package/@noisytransfer/noisystream