Fix deadlock in DTLS shutdown

internal/mux/mux.go

@@ -1,11 +1,14 @@
 package mux
 
 import (
-	"fmt"
 	"net"
 	"sync"
+
+	"github.com/pions/webrtc/pkg/logging"
 )
 
+var muxLog = logging.NewScopedLogger("mux")
+
 // Mux allows multiplexing
 type Mux struct {
 	lock       sync.RWMutex
@@ -100,7 +103,7 @@ func (m *Mux) dispatch(buf []byte) {
 	m.lock.Unlock()
 
 	if endpoint == nil {
-		fmt.Printf("Warning: mux: no endpoint for packet starting with %d\n", buf[0])
+		muxLog.Warnf("Warning: mux: no endpoint for packet starting with %d\n", buf[0])
 		return
 	}
 

peerconnection.go

@@ -1334,8 +1334,8 @@ func (pc *PeerConnection) Close() error {
 	//    Conn if one of the endpoints is closed down. To
 	//    continue the chain the Mux has to be closed.
 
-	for _, t := range pc.rtpTransceivers {
-		if err := t.Stop(); err != nil {
+	if pc.iceTransport != nil {
+		if err := pc.iceTransport.Stop(); err != nil {
 			closeErrs = append(closeErrs, err)
 		}
 	}
@@ -1350,10 +1350,8 @@ func (pc *PeerConnection) Close() error {
 		}
 	}
 
-	// TODO: Close DTLS?
-
-	if pc.iceTransport != nil {
-		if err := pc.iceTransport.Stop(); err != nil {
+	for _, t := range pc.rtpTransceivers {
+		if err := t.Stop(); err != nil {
 			closeErrs = append(closeErrs, err)
 		}
 	}

peerconnection_media_test.go

@@ -289,10 +289,8 @@ func TestPeerConnection_Media_Sender_Transports_OnSelectedCandidatePairChange(t
 
 	pcAnswer.OnICEConnectionStateChange(func(iceState ICEConnectionState) {
 		if iceState == ICEConnectionStateConnected {
-			go func() {
-				time.Sleep(3 * time.Second) // TODO PeerConnection.Close() doesn't block for all subsystems
-				close(iceComplete)
-			}()
+			time.Sleep(3 * time.Second) // TODO PeerConnection.Close() doesn't block for all subsystems
+			close(iceComplete)
 		}
 	})
 

peerconnection_test.go

@@ -10,7 +10,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/pions/transport/test"
 	"github.com/pions/webrtc/internal/ice"
+	"github.com/pions/webrtc/internal/mux"
 
 	"github.com/pions/webrtc/pkg/rtcerr"
 	"github.com/stretchr/testify/assert"
@@ -478,3 +480,50 @@ func TestPeerConnection_EventHandlers(t *testing.T) {
 		<-onDataChannelCalled,
 	}))
 }
+
+// This test asserts that nothing deadlocks we try to shutdown when DTLS is in flight
+// We ensure that DTLS is in flight by removing the mux func for it, so all inbound DTLS is lost
+func TestPeerConnection_ShutdownNoDTLS(t *testing.T) {
+	dtlsMatchFunc := mux.MatchDTLS
+	defer func() {
+		mux.MatchDTLS = dtlsMatchFunc
+	}()
+
+	// Drop all incoming DTLS traffic
+	mux.MatchDTLS = func([]byte) bool {
+		return false
+	}
+
+	lim := test.TimeOut(time.Second * 10)
+	defer lim.Stop()
+
+	api := NewAPI()
+	offerPC, answerPC, err := api.newPair()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err = signalPair(offerPC, answerPC); err != nil {
+		t.Fatal(err)
+	}
+
+	iceComplete := make(chan interface{})
+	answerPC.OnICEConnectionStateChange(func(iceState ICEConnectionState) {
+		if iceState == ICEConnectionStateConnected {
+			time.Sleep(time.Second) // Give time for DTLS to start
+
+			select {
+			case <-iceComplete:
+			default:
+				close(iceComplete)
+			}
+		}
+	})
+
+	<-iceComplete
+	if err = offerPC.Close(); err != nil {
+		t.Fatal(err)
+	} else if err = answerPC.Close(); err != nil {
+		t.Fatal(err)
+	}
+}