Fix for scenario where m-line is revived after being set to port 0.

talk/app/webrtc/peerconnection.cc

 /*
  * libjingle
  * Copyright 2012 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 931 matching lines @@
   if (session_->data_channel_type() == cricket::DCT_SCTP &&
       session_->GetSslRole(&role)) {
     AllocateSctpSids(role);
   }
 
   // Update state and SSRC of local MediaStreams and DataChannels based on the
   // local session description.
   const cricket::ContentInfo* audio_content =
       GetFirstAudioContent(desc->description());
   if (audio_content) {
+    if (audio_content->rejected) {
+      audio_rejected_ = true;
+    } else if (audio_rejected_) {

[pthatcher1, 2015/11/11 00:45:02]

Can we get the equivalent of audio_rejected_ by looking at local_description_
before line 934?  Then we wouldn't need the extra member variable.

[Taylor Brandstetter, 2015/11/11 01:33:29]

It gets more complex if we go that route. We have to check both the remote and
local description. But really what we're interested in is the last answer
description (assuming port 0 offers must be met with port 0 answers). I started
implementing this but it started to feel like overkill for a termporary hack.

+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      audio_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_AUDIO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_AUDIO);

[pthatcher1, 2015/11/11 00:45:02]

Should we have a ReconfigureSenderAndReceivers method?

[Taylor Brandstetter, 2015/11/11 01:33:29]

Done.

+    }
     const cricket::AudioContentDescription* audio_desc =
         static_cast<const cricket::AudioContentDescription*>(
             audio_content->description);
     UpdateLocalTracks(audio_desc->streams(), audio_desc->type());
   }
 
   const cricket::ContentInfo* video_content =
       GetFirstVideoContent(desc->description());
   if (video_content) {
+    if (video_content->rejected) {
+      video_rejected_ = true;
+    } else if (video_rejected_) {
+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      video_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_VIDEO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_VIDEO);
+    }
     const cricket::VideoContentDescription* video_desc =
         static_cast<const cricket::VideoContentDescription*>(
             video_content->description);
     UpdateLocalTracks(video_desc->streams(), video_desc->type());
   }
 
   const cricket::ContentInfo* data_content =
       GetFirstDataContent(desc->description());
   if (data_content) {
     const cricket::DataContentDescription* data_desc =
@@ skipping 45 matching lines @@
   const cricket::SessionDescription* remote_desc = desc->description();
 
   // We wait to signal new streams until we finish processing the description,
   // since only at that point will new streams have all their tracks.
   rtc::scoped_refptr<StreamCollection> new_streams(StreamCollection::Create());
 
   // Find all audio rtp streams and create corresponding remote AudioTracks
   // and MediaStreams.
   const cricket::ContentInfo* audio_content = GetFirstAudioContent(remote_desc);
   if (audio_content) {
+    if (audio_content->rejected) {
+      audio_rejected_ = true;
+    } else if (audio_rejected_) {
+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      audio_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_AUDIO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_AUDIO);
+    }
     const cricket::AudioContentDescription* desc =
         static_cast<const cricket::AudioContentDescription*>(
             audio_content->description);
     UpdateRemoteStreamsList(GetActiveStreams(desc), desc->type(), new_streams);
     remote_info_.default_audio_track_needed =
         !remote_desc->msid_supported() && desc->streams().empty() &&
         MediaContentDirectionHasSend(desc->direction());
   }
 
   // Find all video rtp streams and create corresponding remote VideoTracks
   // and MediaStreams.
   const cricket::ContentInfo* video_content = GetFirstVideoContent(remote_desc);
   if (video_content) {
+    if (video_content->rejected) {
+      video_rejected_ = true;
+    } else if (video_rejected_) {
+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      video_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_VIDEO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_VIDEO);
+    }
     const cricket::VideoContentDescription* desc =
         static_cast<const cricket::VideoContentDescription*>(
             video_content->description);
     UpdateRemoteStreamsList(GetActiveStreams(desc), desc->type(), new_streams);
     remote_info_.default_video_track_needed =
         !remote_desc->msid_supported() && desc->streams().empty() &&
         MediaContentDirectionHasSend(desc->direction());
   }
 
   // Update the DataChannels with the information from the remote peer.
@@ skipping 878 matching lines @@
 
 std::vector<rtc::scoped_refptr<RtpReceiverInterface>>::iterator
 PeerConnection::FindReceiverForTrack(MediaStreamTrackInterface* track) {
   return std::find_if(
       receivers_.begin(), receivers_.end(),
       [track](const rtc::scoped_refptr<RtpReceiverInterface>& receiver) {
         return receiver->track() == track;
       });
 }
 
+void PeerConnection::ReconfigureSenders(cricket::MediaType media_type) {
+  for (const auto& sender : senders_) {
+    if (sender->media_type() == media_type) {
+      sender->Reconfigure();
+    }
+  }
+}
+
+void PeerConnection::ReconfigureReceivers(cricket::MediaType media_type) {
+  for (const auto& receiver : receivers_) {
+    if (receiver->media_type() == media_type) {
+      receiver->Reconfigure();
+    }
+  }
+}
+
 PeerConnection::TrackInfos* PeerConnection::GetRemoteTracks(
     cricket::MediaType media_type) {
   RTC_DCHECK(media_type == cricket::MEDIA_TYPE_AUDIO ||
              media_type == cricket::MEDIA_TYPE_VIDEO);
   return (media_type == cricket::MEDIA_TYPE_AUDIO) ? &remote_audio_tracks_
                                                    : &remote_video_tracks_;
 }
 
 PeerConnection::TrackInfos* PeerConnection::GetLocalTracks(
     cricket::MediaType media_type) {
@@ skipping 19 matching lines @@
 DataChannel* PeerConnection::FindDataChannelBySid(int sid) const {
   for (const auto& channel : sctp_data_channels_) {
     if (channel->id() == sid) {
       return channel;
     }
   }
   return nullptr;
 }
 
 }  // namespace webrtc