Allow cancelling TURN Allocate phase, which can block for ~7.8s if TURN server is not responding.

Author: smb-z

gather.go

@@ -836,7 +836,17 @@ func (a *Agent) gatherCandidatesRelay(ctx context.Context, urls []*stun.URI) {
 				return
 			}
 
+			allocDoneCh := make(chan struct{})
+			go func() {
+				select {
+				case <-ctx.Done():
+					client.Close()
+				case <-allocDoneCh:
+				}
+			}()
+
 			relayConn, err := client.Allocate()
+			close(allocDoneCh)
 			if err != nil {
 				client.Close()
 				closeConnAndLog(locConn, a.log, "failed to allocate on TURN client %s %s", turnServerAddr, err)

gather_vnet_test.go

@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"net"
 	"testing"
+	"time"
 
 	"github.com/pion/logging"
 	"github.com/pion/stun/v3"
@@ -435,3 +436,49 @@ func TestVNetGather_TURNConnectionLeak(t *testing.T) {
 
 	aAgent.gatherCandidatesRelay(context.Background(), []*stun.URI{turnServerURL})
 }
+
+func TestVNetGather_TURNAllocationAbort(t *testing.T) {
+	defer test.CheckRoutines(t)()
+
+	// configure unreachable TURN server
+	turnServerURL := &stun.URI{
+		Scheme:   stun.SchemeTypeTURN,
+		Host:     vnetSTUNServerIP,
+		Port:     vnetSTUNServerPort,
+		Username: "user",
+		Password: "pass",
+		Proto:    stun.ProtoTypeUDP,
+	}
+
+	loggerFactory := logging.NewDefaultLoggerFactory()
+	router, err := vnet.NewRouter(&vnet.RouterConfig{
+		CIDR:          "10.0.0.0/24",
+		LoggerFactory: loggerFactory,
+	})
+
+	nw, err := vnet.NewNet(&vnet.NetConfig{})
+	require.NoError(t, err)
+	require.NoError(t, router.AddNet(nw))
+
+	cfg0 := &AgentConfig{
+		Urls: []*stun.URI{
+			turnServerURL,
+		},
+		NetworkTypes:     supportedNetworkTypes(),
+		MulticastDNSMode: MulticastDNSModeDisabled,
+		Net:              nw,
+	}
+	aAgent, err := NewAgent(cfg0)
+	require.NoError(t, err, "should succeed")
+	defer func() {
+		require.NoError(t, aAgent.Close())
+	}()
+
+	// if not cancelled, gatherCandidatesRelay() will block for ~7.8s
+	defer test.TimeOut(time.Second * 1).Stop()
+
+	ctx, cancelFunc := context.WithTimeout(context.Background(), 500*time.Millisecond)
+	defer cancelFunc()
+
+	aAgent.gatherCandidatesRelay(ctx, []*stun.URI{turnServerURL})
+}