Add WebRTC ICE servers config (#824)

* add ICEServers config

* remove unnecessary check

client.go

@@ -301,6 +301,7 @@ func NewClient(cfg *ClientConfig) (cl *Client, err error) {
 		},
 		Proxy:                      cl.config.HTTPProxy,
 		WebsocketTrackerHttpHeader: cl.config.WebsocketTrackerHttpHeader,
+		ICEServers:                 cl.config.ICEServers,
 		DialContext:                cl.config.TrackerDialContext,
 		OnConn: func(dc datachannel.ReadWriteCloser, dcc webtorrent.DataChannelContext) {
 			cl.lock()

config.go

@@ -181,6 +181,10 @@ type ClientConfig struct {
 
 	Callbacks Callbacks
 
+	// ICEServers defines a slice describing servers available to be used by
+	// ICE, such as STUN and TURN servers.
+	ICEServers []string
+
 	DialRateLimiter *rate.Limiter
 }
 

webtorrent/tracker-client.go

@@ -43,6 +43,7 @@ type TrackerClient struct {
 	pingTicker     *time.Ticker
 
 	WebsocketTrackerHttpHeader func() http.Header
+	ICEServers                 []string
 }
 
 func (me *TrackerClient) Stats() TrackerClientStats {

webtorrent/transport.go

@@ -29,7 +29,6 @@ var (
 		s.DetachDataChannels()
 		return webrtc.NewAPI(webrtc.WithSettingEngine(s))
 	}()
-	config              = webrtc.Configuration{ICEServers: []webrtc.ICEServer{{URLs: []string{"stun:stun.l.google.com:19302"}}}}
 	newPeerConnectionMu sync.Mutex
 )
 
@@ -49,11 +48,14 @@ func (me *wrappedPeerConnection) Close() error {
 	return err
 }
 
-func newPeerConnection(logger log.Logger) (*wrappedPeerConnection, error) {
+func newPeerConnection(logger log.Logger, iceServers []string) (*wrappedPeerConnection, error) {
 	newPeerConnectionMu.Lock()
 	defer newPeerConnectionMu.Unlock()
 	ctx, span := otel.Tracer(tracerName).Start(context.Background(), "PeerConnection")
-	pc, err := api.NewPeerConnection(config)
+
+	pcConfig := webrtc.Configuration{ICEServers: []webrtc.ICEServer{{URLs: iceServers}}}
+
+	pc, err := api.NewPeerConnection(pcConfig)
 	if err != nil {
 		span.SetStatus(codes.Error, err.Error())
 		span.RecordError(err)
@@ -99,7 +101,7 @@ func (tc *TrackerClient) newOffer(
 	offer webrtc.SessionDescription,
 	err error,
 ) {
-	peerConnection, err = newPeerConnection(logger)
+	peerConnection, err = newPeerConnection(logger, tc.ICEServers)
 	if err != nil {
 		return
 	}
@@ -191,7 +193,7 @@ func (tc *TrackerClient) newAnsweringPeerConnection(
 ) (
 	peerConn *wrappedPeerConnection, answer webrtc.SessionDescription, err error,
 ) {
-	peerConn, err = newPeerConnection(tc.Logger)
+	peerConn, err = newPeerConnection(tc.Logger, tc.ICEServers)
 	if err != nil {
 		err = fmt.Errorf("failed to create new connection: %w", err)
 		return

wstracker.go

@@ -45,6 +45,7 @@ type websocketTrackers struct {
 	Proxy                      httpTracker.ProxyFunc
 	DialContext                func(ctx context.Context, network, addr string) (net.Conn, error)
 	WebsocketTrackerHttpHeader func() netHttp.Header
+	ICEServers                 []string
 }
 
 func (me *websocketTrackers) Get(url string, infoHash [20]byte) (*webtorrent.TrackerClient, func()) {
@@ -64,6 +65,7 @@ func (me *websocketTrackers) Get(url string, infoHash [20]byte) (*webtorrent.Tra
 					return fmt.Sprintf("tracker client for %q: %v", url, m)
 				}),
 				WebsocketTrackerHttpHeader: me.WebsocketTrackerHttpHeader,
+				ICEServers:                 me.ICEServers,
 			},
 		}
 		value.TrackerClient.Start(func(err error) {