MT#55283 add handler_func_passthrough_stub

The stub is used for unknown payload types. Specialise the handler
function for it with an extra check for DTX usage. This effectively
blocks RTP packets with unknown payload types if DTX has been
configured. Forwarding RTP packets with unknown payload types can
interfere with a clean output stream generated by the DTX buffer.

Change-Id: I6f0aa9654946d2877b963cd13cec7c3f5c8b1c54

daemon/codec.c

@@ -306,6 +306,7 @@ static void codec_output_rtp_seq_own(struct media_packet *mp, struct codec_sched
 
 
 static codec_handler_func handler_func_passthrough_ssrc;
+static codec_handler_func handler_func_passthrough_stub;
 static codec_handler_func handler_func_transcode;
 static codec_handler_func handler_func_playback;
 static codec_handler_func handler_func_inject_dtmf;
@@ -360,7 +361,7 @@ static void __buffer_delay_seq(struct delay_buffer *dbuf, struct media_packet *m
 static struct codec_handler codec_handler_stub_ssrc = {
 	.source_pt.payload_type = -1,
 	.dest_pt.payload_type = -1,
-	.handler_func = handler_func_passthrough_ssrc,
+	.handler_func = handler_func_passthrough_stub,
 	.kernelize = true,
 	.passthrough = true,
 };
@@ -2942,6 +2943,14 @@ void codec_init_payload_type(rtp_payload_type *pt, enum media_type type) {
 #ifdef WITH_TRANSCODING
 
 
+static int handler_func_passthrough_stub(struct codec_handler *h, struct media_packet *mp) {
+	if (G_UNLIKELY(!mp->rtp))
+		return handler_func_passthrough(h, mp);
+	if (rtpe_config.dtx_delay)
+		return 0;
+	return handler_func_passthrough_ssrc(h, mp);
+}
+
 static int handler_func_passthrough_ssrc(struct codec_handler *h, struct media_packet *mp) {
 	if (G_UNLIKELY(!mp->rtp))
 		return handler_func_passthrough(h, mp);