Fix RTPSender.GetParameters crash

Sean-Der · Sean-Der · commit 26ce88e87a1f · 2021-12-26T22:50:52.000-05:00
If a RTPSender doesn't have a track currently set and GetParameters is called we would call a method on a nil pointer. Now instead of checking the Track kind we store the kind in the RTPSender. Resolves pion#2065
diff --git a/rtpsender.go b/rtpsender.go
@@ -26,6 +26,7 @@ type RTPSender struct {
 	transport *DTLSTransport
 
 	payloadType PayloadType
+	kind        RTPCodecType
 	ssrc        SSRC
 
 	// nolint:godox
@@ -66,6 +67,7 @@ func (api *API) NewRTPSender(track TrackLocal, transport *DTLSTransport) (*RTPSe
 		ssrc:       SSRC(randutil.NewMathRandomGenerator().Uint32()),
 		id:         id,
 		srtpStream: &srtpWriterFuture{},
+		kind:       track.Kind(),
 	}
 
 	r.srtpStream.rtpSender = r
@@ -107,7 +109,7 @@ func (r *RTPSender) Transport() *DTLSTransport {
 func (r *RTPSender) getParameters() RTPSendParameters {
 	sendParameters := RTPSendParameters{
 		RTPParameters: r.api.mediaEngine.getRTPParametersByKind(
-			r.track.Kind(),
+			r.kind,
 			[]RTPTransceiverDirection{RTPTransceiverDirectionSendonly},
 		),
 		Encodings: []RTPEncodingParameters{
@@ -122,7 +124,7 @@ func (r *RTPSender) getParameters() RTPSendParameters {
 	if r.rtpTransceiver != nil {
 		sendParameters.Codecs = r.rtpTransceiver.getCodecs()
 	} else {
-		sendParameters.Codecs = r.api.mediaEngine.getCodecsByKind(r.track.Kind())
+		sendParameters.Codecs = r.api.mediaEngine.getCodecsByKind(r.kind)
 	}
 	return sendParameters
 }
@@ -149,7 +151,7 @@ func (r *RTPSender) ReplaceTrack(track TrackLocal) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
-	if track != nil && r.rtpTransceiver.kind != track.Kind() {
+	if track != nil && r.kind != track.Kind() {
 		return ErrRTPSenderNewTrackHasIncorrectKind
 	}
 
diff --git a/rtpsender_test.go b/rtpsender_test.go
@@ -255,3 +255,19 @@ func Test_RTPSender_ReplaceTrack_InvalidCodecChange(t *testing.T) {
 
 	closePairNow(t, sender, receiver)
 }
+
+func Test_RTPSender_GetParameters_NilTrack(t *testing.T) {
+	track, err := NewTrackLocalStaticSample(RTPCodecCapability{MimeType: MimeTypeVP8}, "video", "pion")
+	assert.NoError(t, err)
+
+	peerConnection, err := NewPeerConnection(Configuration{})
+	assert.NoError(t, err)
+
+	rtpSender, err := peerConnection.AddTrack(track)
+	assert.NoError(t, err)
+
+	assert.NoError(t, rtpSender.ReplaceTrack(nil))
+	rtpSender.GetParameters()
+
+	assert.NoError(t, peerConnection.Close())
+}
