Senden voice and video relay

Note: This project is currently halted. Senden will use WebRTC for the foreseeable future. This is mostly due to incompatibility with browsers/clients.

Senden relay is a Rust relay server for forwarding voice and video between users in a call. It uses WebTransport (QUIC/HTTP3) for media transport. It can be operated as part of a self hosted Senden node in the future.

Prerequisites

• Rust installed https://rustup.rs
• A TLS certificate and key (required for WebTransport; see TLS setup)

If you would like to sponsor a node, please contact us at contact@wireway.ch.

First-time setup

1. Generate the API key

The relay uses a pre-shared key to authenticate requests from the backend. On first run, set SETUP_RELAYKEY to your chosen secret:

SETUP_RELAYKEY=your-secret-key cargo run

2. TLS setup

WebTransport requires a valid TLS certificate. You have two options:

Let certbot generate a certificate:

SETUP_TLS_DOMAIN=relay.example.com SETUP_TLS_EMAIL=you@example.com cargo run

This runs certbot certonly --standalone for the domain and prints the resulting cert paths. Certbot must be installed and port 80 must be open. After it completes, use the printed paths as CERT_PATH/KEY_PATH when starting the relay.

Use already existing certificate

Set CERT_PATH and KEY_PATH directly (see Environment variables).

Running

# Development
cargo run

# Production
cargo build --release
CERT_PATH=/path/to/cert.pem KEY_PATH=/path/to/key.pem ./target/release/senden-relay

You should configure a systemd job to run this. If you don't know how to do this, you should probably not host this.

Running tests

cargo test

Environment variables

Variable	Default	Description
PORT	3000	HTTP/management API port
WT_PORT	4433	WebTransport (QUIC) port
CERT_PATH	-	Path to TLS certificate PEM file
KEY_PATH	-	Path to TLS private key PEM file
RUST_LOG	info	Log level (trace, debug, info, warn, error)
SETUP_RELAYKEY	-	One-time: plain-text API key to hash and save
SETUP_TLS_DOMAIN	-	One-time: domain to obtain a Let's Encrypt cert for
SETUP_TLS_EMAIL	-	Optional email for Let's Encrypt registration

API

All management endpoints require Authorization: Bearer <api-key> using the plain-text key set during first-time setup.

Method	Path	Description
GET	/health	Server health, uptime, active room count
POST	/v1/management/{room_id}/allocate	Allocate a WebTransport token for a user
DELETE	/v1/management/{room_id}	Delete a room and disconnect all participants
DELETE	/v1/management/{room_id}/users/{user_id}	Remove a single user from a room
GET	/room/{room_id}	List connected user IDs in a room

In debug builds, a Swagger UI is available at http://localhost:3000/swagger-ui.