Handle padded audio packets correctly

webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.cc b/webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.cc
index acc5926e5b5829db837678226958890b0f90ebb8..e3237948fb323e3b6a152d82f03b6338e5e7690c 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_audio.cc
@@ -212,9 +212,10 @@ int32_t RTPReceiverAudio::ParseAudioCodecSpecific(
     size_t payload_length,
     const AudioPayload& audio_specific,
     bool is_red) {
-
   if (payload_length == 0) {

[minyue-webrtc, 2017/05/10 13:03:18]

I tried it, and I am afraid OnReceivedPayloadData(nullptr, 0) will never be
called.

For a quick hack, you need if (payload_length ==
rtp_header->header.paddingLength)

But this put me into great doubt about how the whole padding should work with
neteq. We should be receiving some garbage for current implementation (I
actually hear some burst of noise in video_loopback test and wondered why)

-    return 0;
+    rtp_header->type.Audio.isCNG = false;
+    rtp_header->frameType = kEmptyFrame;
+    return data_callback_->OnReceivedPayloadData(nullptr, 0, rtp_header);
   }
 
   bool telephone_event_packet =
@@ -239,6 +240,7 @@ int32_t RTPReceiverAudio::ParseAudioCodecSpecific(
       number_of_events = MAX_NUMBER_OF_PARALLEL_TELEPHONE_EVENTS;
     }
     for (size_t n = 0; n < number_of_events; ++n) {
+      RTC_DCHECK_GE(payload_length, (4 * n) + 2);
       bool end = (payload_data[(4 * n) + 1] & 0x80) ? true : false;
 
       std::set<uint8_t>::iterator event =
@@ -291,6 +293,7 @@ int32_t RTPReceiverAudio::ParseAudioCodecSpecific(
     }
   }
   // TODO(holmer): Break this out to have RED parsing handled generically.
+  RTC_DCHECK_GT(payload_length, 0);
   if (is_red && !(payload_data[0] & 0x80)) {
     // we recive only one frame packed in a RED packet remove the RED wrapper
     rtp_header->header.payloadType = payload_data[0];