Moblink Rust Relay

Use spare devices as extra SRTLA bonding connections. The same functionality is part of Moblin on iOS.

Originally inspired by the Moblink Kotlin/Android code.

Features

• WebSocket Connection: Connects to Moblin via WebSocket (e.g., wss://...)
• Auth Handling: Implements the same challenge–response authentication logic as the Android client
• UDP Relay: Forwards UDP packets between the remote streamer and a local destination.
• mDNS: Automatically connect to nearby Moblink devices.

Requirements

• Rust (stable, e.g., 1.70+)
• Cargo (for building)

Usage

# 1. Clone this repository (or copy the code)
git clone https://github.com/datagutt/moblink-rust-relay.git
cd moblink-rust-relay

# Set nightly (optional)
rustup override set nightly

# 2. Build the project
cargo build --release

# 3. Run the relay
./target/release/moblink-rust-relay \
  --name "RelayName" \
  --id "UUID" \
  --streamer-url ws://192.168.1.2:7777 \
  --password "secret123" \
  --bind-address 192.168.1.10
  --log-level debug

Command-Line Arguments

Argument	Description	Default	Example
--name	Name to identify the relay	Relay	--name CameraRelay1
--id	UUID to identify the Relay	Generated	--id UUID
--streamer-url	WebSocket URL to connect to the streamer	None (multicast DNS)	--streamer-url wss://example.com/ws
--password	Password used in the challenge–response authentication	None	--password mySecret
--log-level	Logging verbosity (e.g., error, warn, info, debug, trace)	info	--log-level debug
--bind-address	Local modem IP address to bind for UDP socket	0.0.0.0	--bind-address 192.168.1.10
--status-executable	Status executable. Print status to standard output on format {"batteryPercentage": 93}	None	--status-executable ./status.sh
--status-file	Status file. Contains status on format {"batteryPercentage": 93}	None	--status-file status.json

Relay status (today only battery percentage) is sent to the streamer if --status-executable or --status-file is given and outputting a valid JSON object as seen above.

Bind to multiple addresses/interface

We no longer support binding to multiple addresses. Please start multiple instances of the relay for each interface.

Architecture

1. WebSocket Connection

   • Establishes a WebSocket to streamer_url, or if not provided, tries to find nearby Moblink streamers through multicast DNS.
   • Handles “Hello” messages, calculates authentication, and sends an “Identify” message.

2. Handling Requests

   • When a startTunnel request is received, the relay spawns two async tasks:
     • (relay_to_destination): Forwards traffic from streamer → destination
     • (relay_to_streamer): Forwards traffic from destination → streamer

3. UDP Binding

   • By default, it binds a UDP socket to whatever we deem to be the main network interface.

FAQ

Q: How do I integrate this into my own application?
A: Use the moblink-rust crate

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License: This project is distributed under the terms of the MIT license.

Enjoy using Moblink Rust Relay!