webrtc: fix deadlock when a WHEP source fails (#3062) (#3108) (#3110)

Co-authored-by: Jonathan Martin <jonathan.martin@marss.com>
Co-authored-by: aler9 <46489434+aler9@users.noreply.github.com>

internal/protocols/webrtc/peer_connection.go

@@ -36,9 +36,12 @@ type PeerConnection struct {
 	newLocalCandidate chan *webrtc.ICECandidateInit
 	connected         chan struct{}
 	disconnected      chan struct{}
-	closed            chan struct{}
+	done              chan struct{}
 	gatheringDone     chan struct{}
 	incomingTrack     chan trackRecvPair
+
+	ctx       context.Context
+	ctxCancel context.CancelFunc
 }
 
 // Start starts the peer connection.
@@ -56,10 +59,12 @@ func (co *PeerConnection) Start() error {
 	co.newLocalCandidate = make(chan *webrtc.ICECandidateInit)
 	co.connected = make(chan struct{})
 	co.disconnected = make(chan struct{})
-	co.closed = make(chan struct{})
+	co.done = make(chan struct{})
 	co.gatheringDone = make(chan struct{})
 	co.incomingTrack = make(chan trackRecvPair)
 
+	co.ctx, co.ctxCancel = context.WithCancel(context.Background())
+
 	if !co.Publish {
 		_, err = co.wr.AddTransceiverFromKind(webrtc.RTPCodecTypeVideo, webrtc.RtpTransceiverInit{
 			Direction: webrtc.RTPTransceiverDirectionRecvonly,
@@ -80,7 +85,7 @@ func (co *PeerConnection) Start() error {
 		co.wr.OnTrack(func(track *webrtc.TrackRemote, receiver *webrtc.RTPReceiver) {
 			select {
 			case co.incomingTrack <- trackRecvPair{track, receiver}:
-			case <-co.closed:
+			case <-co.ctx.Done():
 			}
 		})
 	}
@@ -90,7 +95,7 @@ func (co *PeerConnection) Start() error {
 		defer co.stateChangeMutex.Unlock()
 
 		select {
-		case <-co.closed:
+		case <-co.done:
 			return
 		default:
 		}
@@ -108,7 +113,7 @@ func (co *PeerConnection) Start() error {
 			close(co.disconnected)
 
 		case webrtc.PeerConnectionStateClosed:
-			close(co.closed)
+			close(co.done)
 		}
 	})
 
@@ -118,7 +123,7 @@ func (co *PeerConnection) Start() error {
 			select {
 			case co.newLocalCandidate <- &v:
 			case <-co.connected:
-			case <-co.closed:
+			case <-co.ctx.Done():
 			}
 		} else {
 			close(co.gatheringDone)
@@ -130,8 +135,9 @@ func (co *PeerConnection) Start() error {
 
 // Close closes the connection.
 func (co *PeerConnection) Close() {
+	co.ctxCancel()
 	co.wr.Close() //nolint:errcheck
-	<-co.closed
+	<-co.done
 }
 
 // CreatePartialOffer creates a partial offer.

internal/protocols/webrtc/peer_connection_test.go

@@ -0,0 +1,33 @@
+package webrtc
+
+import (
+	"testing"
+	"time"
+
+	"github.com/bluenviron/mediamtx/internal/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPeerConnectionCloseAfterError(t *testing.T) {
+	api, err := NewAPI(APIConf{
+		LocalRandomUDP:    true,
+		IPsFromInterfaces: true,
+	})
+	require.NoError(t, err)
+
+	pc := &PeerConnection{
+		API:     api,
+		Publish: false,
+		Log:     test.NilLogger{},
+	}
+	err = pc.Start()
+	require.NoError(t, err)
+
+	_, err = pc.CreatePartialOffer()
+	require.NoError(t, err)
+
+	// wait for ICE candidates to be generated
+	time.Sleep(500 * time.Millisecond)
+
+	pc.Close()
+}

internal/protocols/webrtc/whip_client.go

@@ -89,7 +89,7 @@ outer:
 	for {
 		select {
 		case ca := <-c.pc.NewLocalCandidate():
-			err := WHIPPatchCandidate(context.Background(), c.HTTPClient, c.URL.String(), offer, res.ETag, ca)
+			err := WHIPPatchCandidate(ctx, c.HTTPClient, c.URL.String(), offer, res.ETag, ca)
 			if err != nil {
 				c.pc.Close()
 				return nil, err
@@ -180,7 +180,7 @@ outer:
 	for {
 		select {
 		case ca := <-c.pc.NewLocalCandidate():
-			err := WHIPPatchCandidate(context.Background(), c.HTTPClient, c.URL.String(), offer, res.ETag, ca)
+			err := WHIPPatchCandidate(ctx, c.HTTPClient, c.URL.String(), offer, res.ETag, ca)
 			if err != nil {
 				c.pc.Close()
 				return nil, err