Fix goroutine leaks when using datachannel with a multi mux with single port

datachannel_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/pion/ice/v3"
 	"github.com/pion/transport/v3/test"
 	"github.com/stretchr/testify/assert"
 )
@@ -360,6 +361,26 @@ func TestDataChannel_Close(t *testing.T) {
 		assert.NoError(t, dc.Close())
 		closePairNow(t, offerPC, answerPC)
 	})
+
+	t.Run("Close after PeerConnection With Mux Closed", func(t *testing.T) {
+		mux, err := ice.NewMultiUDPMuxFromPort(8443)
+		if err != nil {
+			panic(err)
+		}
+
+		offerPC, answerPC, err := newPairWithMux(mux)
+		assert.NoError(t, err)
+
+		dc, err := offerPC.CreateDataChannel(expectedLabel, nil)
+		assert.NoError(t, err)
+
+		closePairNow(t, offerPC, answerPC)
+		assert.NoError(t, dc.Close())
+
+		// close the mux here just a test, it is confirmed when close the mux the go routine won't be leaks
+		// but in SFU context, as explain in the issue https://github.com/pion/webrtc/issues/2738 the mux is never closed.
+		// assert.NoError(t, mux.Close())
+	})
 }
 
 func TestDataChannelParameters(t *testing.T) {

peerconnection_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/pion/ice/v3"
 	"github.com/pion/sdp/v3"
 	"github.com/pion/transport/v3/test"
 	"github.com/pion/webrtc/v4/pkg/rtcerr"
@@ -32,6 +33,24 @@ func newPair() (pcOffer *PeerConnection, pcAnswer *PeerConnection, err error) {
 	return pca, pcb, nil
 }
 
+func newPairWithMux(mux *ice.MultiUDPMuxDefault) (*PeerConnection, *PeerConnection, error) {
+	settingEngine := SettingEngine{}
+
+	settingEngine.SetICEUDPMux(mux)
+	api := NewAPI(WithSettingEngine(settingEngine))
+	pca, err := api.NewPeerConnection(Configuration{})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	pcb, err := NewPeerConnection(Configuration{})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return pca, pcb, nil
+}
+
 func signalPairWithModification(pcOffer *PeerConnection, pcAnswer *PeerConnection, modificationFunc func(string) string) error {
 	// Note(albrow): We need to create a data channel in order to trigger ICE
 	// candidate gathering in the background for the JavaScript/Wasm bindings. If