datachannel-rs  

Rust wrappers for libdatachannel, a WebRTC Data Channels standalone implementation in C++.

Usage

This crate provides two traits that end user must implement, DataChannel and PeerConnection, that define all available callback methods. Note that all methods have a default no-operation implementation.

Aforementioned traits are defined as follows:

pub trait DataChannel {
    fn on_open(&mut self) {}
    fn on_closed(&mut self) {}
    fn on_error(&mut self, err: &str) {}
    fn on_message(&mut self, msg: &[u8]) {}
    fn on_buffered_amount_low(&mut self) {}
    fn on_available(&mut self) {}
}

pub trait PeerConnection {
    type DC;

    fn on_description(&mut self, sess_desc: SessionDescription) {}
    fn on_candidate(&mut self, cand: IceCandidate) {}
    fn on_connection_state_change(&mut self, state: ConnectionState) {}
    fn on_gathering_state_change(&mut self, state: GatheringState) {}
    fn on_data_channel(&mut self, data_channel: Box<RtcDataChannel<Self::DC>>) {}
}

Traits implementations are meant to be used through RtcPeerConnection and RtcDataChannel structs.

The main struct, RtcPeerconnection, takes a Config (which defines ICE servers) and a MakeDataChannel instance (a factory trait used internally for on_data_channel callback). Note that this factory trait has a straightforward blanket implementation for Clone types.

Here is the basic workflow:

use datachannel::{Config, DataChannel, PeerConnection, RtcPeerConnection};

struct Chan;
impl DataChannel for Chan {}

struct Conn;
impl PeerConnection for Conn {}

let ice_servers = vec!["stun:stun.l.google.com:19302".to_string()];
let conf = Config::new(ice_servers);

let mut pc = RtcPeerConnection::new(&conf, Conn, || Chan)?;

let mut dc = pc.create_data_channel("test-dc", Chan)?;
dc.send("Hello Peer!".as_bytes())?;

Complete implementation example can be found in the tests.

Packaging

By default libdatachannel will be built and linked dynamically. However there is a static Cargo feature that will build and link it statically (with all its dependencies).

Note that CMake is required to compile libdatachannel through datachannel-sys.