app/webrtc/mediastreamsignaling.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,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "talk/app/webrtc/mediastreamsignaling.h"

#include <vector>

#include "talk/app/webrtc/audiotrack.h"
#include "talk/app/webrtc/mediastreamproxy.h"
#include "talk/app/webrtc/mediaconstraintsinterface.h"
#include "talk/app/webrtc/mediastreamtrackproxy.h"
#include "talk/app/webrtc/remotevideocapturer.h"
#include "talk/app/webrtc/videosource.h"
#include "talk/app/webrtc/videotrack.h"
#include "talk/base/bytebuffer.h"
#include "talk/base/stringutils.h"
#include "talk/media/sctp/sctpdataengine.h"

static const char kDefaultStreamLabel[] = "default";
static const char kDefaultAudioTrackLabel[] = "defaulta0";
static const char kDefaultVideoTrackLabel[] = "defaultv0";

namespace webrtc {

using talk_base::scoped_ptr;
using talk_base::scoped_refptr;

// Supported MediaConstraints.
const char MediaConstraintsInterface::kOfferToReceiveAudio[] =
    "OfferToReceiveAudio";
const char MediaConstraintsInterface::kOfferToReceiveVideo[] =
    "OfferToReceiveVideo";
const char MediaConstraintsInterface::kIceRestart[] =
    "IceRestart";
const char MediaConstraintsInterface::kUseRtpMux[] =
    "googUseRtpMUX";
const char MediaConstraintsInterface::kVoiceActivityDetection[] =
    "VoiceActivityDetection";

static bool ParseConstraints(
    const MediaConstraintsInterface* constraints,
    cricket::MediaSessionOptions* options, bool is_answer) {
  bool value;
  size_t mandatory_constraints_satisfied = 0;

  if (FindConstraint(constraints,
                     MediaConstraintsInterface::kOfferToReceiveAudio,
                     &value, &mandatory_constraints_satisfied)) {
    // |options-|has_audio| can only change from false to
    // true, but never change from true to false. This is to make sure
    // CreateOffer / CreateAnswer doesn't remove a media content
    // description that has been created.
    options->has_audio |= value;
  } else {
    // kOfferToReceiveAudio defaults to true according to spec.
    options->has_audio = true;
  }

  if (FindConstraint(constraints,
                     MediaConstraintsInterface::kOfferToReceiveVideo,
                     &value, &mandatory_constraints_satisfied)) {
    // |options->has_video| can only change from false to
    // true, but never change from true to false. This is to make sure
    // CreateOffer / CreateAnswer doesn't remove a media content
    // description that has been created.
    options->has_video |= value;
  } else {
    // kOfferToReceiveVideo defaults to false according to spec. But
    // if it is an answer and video is offered, we should still accept video
    // per default.
    options->has_video |= is_answer;
  }

  if (FindConstraint(constraints,
                     MediaConstraintsInterface::kVoiceActivityDetection,
                     &value, &mandatory_constraints_satisfied)) {
    options->vad_enabled = value;
  }

  if (FindConstraint(constraints,
                     MediaConstraintsInterface::kUseRtpMux,
                     &value, &mandatory_constraints_satisfied)) {
    options->bundle_enabled = value;
  } else {
    // kUseRtpMux defaults to true according to spec.
    options->bundle_enabled = true;
  }
  if (FindConstraint(constraints,
                     MediaConstraintsInterface::kIceRestart,
                     &value, &mandatory_constraints_satisfied)) {
    options->transport_options.ice_restart = value;
  } else {
    // kIceRestart defaults to false according to spec.
    options->transport_options.ice_restart = false;
  }

  if (!constraints) {
    return true;
  }
  return mandatory_constraints_satisfied == constraints->GetMandatory().size();
}

// Returns true if if at least one media content is present and
// |options.bundle_enabled| is true.
// Bundle will be enabled  by default if at least one media content is present
// and the constraint kUseRtpMux has not disabled bundle.
static bool EvaluateNeedForBundle(const cricket::MediaSessionOptions& options) {
  return options.bundle_enabled &&
      (options.has_audio || options.has_video || options.has_data());
}

// Factory class for creating remote MediaStreams and MediaStreamTracks.
class RemoteMediaStreamFactory {
 public:
  explicit RemoteMediaStreamFactory(talk_base::Thread* signaling_thread,
                                    cricket::ChannelManager* channel_manager)
      : signaling_thread_(signaling_thread),
        channel_manager_(channel_manager) {
  }

  talk_base::scoped_refptr<MediaStreamInterface> CreateMediaStream(
      const std::string& stream_label) {
    return MediaStreamProxy::Create(
        signaling_thread_, MediaStream::Create(stream_label));
  }

  AudioTrackInterface* AddAudioTrack(webrtc::MediaStreamInterface* stream,
                                     const std::string& track_id) {
    return AddTrack<AudioTrackInterface, AudioTrack, AudioTrackProxy>(
        stream, track_id, static_cast<AudioSourceInterface*>(NULL));
  }

  VideoTrackInterface* AddVideoTrack(webrtc::MediaStreamInterface* stream,
                                     const std::string& track_id) {
    return AddTrack<VideoTrackInterface, VideoTrack, VideoTrackProxy>(
        stream, track_id, VideoSource::Create(channel_manager_,
                                              new RemoteVideoCapturer(),
                                              NULL).get());
  }

 private:
  template <typename TI, typename T, typename TP, typename S>
  TI* AddTrack(MediaStreamInterface* stream, const std::string& track_id,
               S* source) {
    talk_base::scoped_refptr<TI> track(
        TP::Create(signaling_thread_, T::Create(track_id, source)));
    track->set_state(webrtc::MediaStreamTrackInterface::kLive);
    if (stream->AddTrack(track)) {
      return track;
    }
    return NULL;
  }

  talk_base::Thread* signaling_thread_;
  cricket::ChannelManager* channel_manager_;
};

MediaStreamSignaling::MediaStreamSignaling(
    talk_base::Thread* signaling_thread,
    MediaStreamSignalingObserver* stream_observer,
    cricket::ChannelManager* channel_manager)
    : signaling_thread_(signaling_thread),
      data_channel_factory_(NULL),
      stream_observer_(stream_observer),
      local_streams_(StreamCollection::Create()),
      remote_streams_(StreamCollection::Create()),
      remote_stream_factory_(new RemoteMediaStreamFactory(signaling_thread,
                                                          channel_manager)),
      last_allocated_sctp_even_sid_(-2),
      last_allocated_sctp_odd_sid_(-1) {
  options_.has_video = false;
  options_.has_audio = false;
}

MediaStreamSignaling::~MediaStreamSignaling() {
}

void MediaStreamSignaling::TearDown() {
  OnAudioChannelClose();
  OnVideoChannelClose();
  OnDataChannelClose();
}

bool MediaStreamSignaling::IsSctpSidAvailable(int sid) const {
  if (sid < 0 || sid > static_cast<int>(cricket::kMaxSctpSid))
    return false;
  for (DataChannels::const_iterator iter = data_channels_.begin();
       iter != data_channels_.end();
       ++iter) {
    if (iter->second->id() == sid) {
      return false;
    }
  }
  return true;
}

// Gets the first unused odd/even id based on the DTLS role. If |role| is
// SSL_CLIENT, the allocated id starts from 0 and takes even numbers; otherwise,
// the id starts from 1 and takes odd numbers. Returns false if no id can be
// allocated.
bool MediaStreamSignaling::AllocateSctpSid(talk_base::SSLRole role, int* sid) {
  int& last_id = (role == talk_base::SSL_CLIENT) ?
      last_allocated_sctp_even_sid_ : last_allocated_sctp_odd_sid_;

  do {
    last_id += 2;
  } while (last_id <= static_cast<int>(cricket::kMaxSctpSid) &&
           !IsSctpSidAvailable(last_id));

  if (last_id > static_cast<int>(cricket::kMaxSctpSid)) {
    return false;
  }

  *sid = last_id;
  return true;
}

bool MediaStreamSignaling::HasDataChannels() const {
  return !data_channels_.empty();
}

bool MediaStreamSignaling::AddDataChannel(DataChannel* data_channel) {
  ASSERT(data_channel != NULL);
  if (data_channels_.find(data_channel->label()) != data_channels_.end()) {
    LOG(LS_ERROR) << "DataChannel with label " << data_channel->label()
                  << " already exists.";
    return false;
  }
  data_channels_[data_channel->label()] = data_channel;
  return true;
}

bool MediaStreamSignaling::AddDataChannelFromOpenMessage(
    const std::string& label,
    const DataChannelInit& config) {
  if (!data_channel_factory_) {
    LOG(LS_WARNING) << "Remote peer requested a DataChannel but DataChannels "
                    << "are not supported.";
    return false;
  }

  if (data_channels_.find(label) != data_channels_.end()) {
    LOG(LS_ERROR) << "DataChannel with label " << label
                  << " already exists.";
    return false;
  }
  scoped_refptr<DataChannel> channel(
      data_channel_factory_->CreateDataChannel(label, &config));
  if (!channel.get()) {
    LOG(LS_ERROR) << "Failed to create DataChannel from the OPEN message.";
    return false;
  }
  data_channels_[label] = channel;
  stream_observer_->OnAddDataChannel(channel);
  // It's immediately ready to use.
  channel->OnChannelReady(true);
  return true;
}

bool MediaStreamSignaling::AddLocalStream(MediaStreamInterface* local_stream) {
  if (local_streams_->find(local_stream->label()) != NULL) {
    LOG(LS_WARNING) << "MediaStream with label " << local_stream->label()
                    << "already exist.";
    return false;
  }
  local_streams_->AddStream(local_stream);

  // Find tracks that has already been configured in SDP. This can occur if a
  // local session description that contains the MSID of these tracks is set
  // before AddLocalStream is called. It can also occur if the local session
  // description is not changed and RemoveLocalStream
  // is called and later AddLocalStream is called again with the same stream.
  AudioTrackVector audio_tracks = local_stream->GetAudioTracks();
  for (AudioTrackVector::const_iterator it = audio_tracks.begin();
       it != audio_tracks.end(); ++it) {
    TrackInfos::const_iterator track_info_it =
        local_audio_tracks_.find((*it)->id());
    if (track_info_it != local_audio_tracks_.end()) {
      const TrackInfo& info = track_info_it->second;
      OnLocalTrackSeen(info.stream_label, info.track_id, info.ssrc,
                       cricket::MEDIA_TYPE_AUDIO);
    }
  }

  VideoTrackVector video_tracks = local_stream->GetVideoTracks();
  for (VideoTrackVector::const_iterator it = video_tracks.begin();
       it != video_tracks.end(); ++it) {
    TrackInfos::const_iterator track_info_it =
        local_video_tracks_.find((*it)->id());
    if (track_info_it != local_video_tracks_.end()) {
      const TrackInfo& info = track_info_it->second;
      OnLocalTrackSeen(info.stream_label, info.track_id, info.ssrc,
                       cricket::MEDIA_TYPE_VIDEO);
    }
  }
  return true;
}

void MediaStreamSignaling::RemoveLocalStream(
    MediaStreamInterface* local_stream) {
  local_streams_->RemoveStream(local_stream);
  stream_observer_->OnRemoveLocalStream(local_stream);
}

bool MediaStreamSignaling::GetOptionsForOffer(
    const MediaConstraintsInterface* constraints,
    cricket::MediaSessionOptions* options) {
  UpdateSessionOptions();
  if (!ParseConstraints(constraints, &options_, false)) {
    return false;
  }
  options_.bundle_enabled = EvaluateNeedForBundle(options_);
  *options = options_;
  return true;
}

bool MediaStreamSignaling::GetOptionsForAnswer(
    const MediaConstraintsInterface* constraints,
    cricket::MediaSessionOptions* options) {
  UpdateSessionOptions();

  // Copy the |options_| to not let the flag MediaSessionOptions::has_audio and
  // MediaSessionOptions::has_video affect subsequent offers.
  cricket::MediaSessionOptions current_options = options_;
  if (!ParseConstraints(constraints, &current_options, true)) {
    return false;
  }
  current_options.bundle_enabled = EvaluateNeedForBundle(current_options);
  *options = current_options;
  return true;
}

// Updates or creates remote MediaStream objects given a
// remote SessionDesription.
// If the remote SessionDesription contains new remote MediaStreams
// the observer OnAddStream method is called. If a remote MediaStream is missing
// from the remote SessionDescription OnRemoveStream is called.
void MediaStreamSignaling::OnRemoteDescriptionChanged(
    const SessionDescriptionInterface* desc) {
  const cricket::SessionDescription* remote_desc = desc->description();
  talk_base::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) {
    const cricket::AudioContentDescription* desc =
        static_cast<const cricket::AudioContentDescription*>(
            audio_content->description);
    UpdateRemoteStreamsList(desc->streams(), desc->type(), new_streams);
    remote_info_.default_audio_track_needed =
        desc->direction() == cricket::MD_SENDRECV && desc->streams().empty();
  }

  // Find all video rtp streams and create corresponding remote VideoTracks
  // and MediaStreams.
  const cricket::ContentInfo* video_content = GetFirstVideoContent(remote_desc);
  if (video_content) {
    const cricket::VideoContentDescription* desc =
        static_cast<const cricket::VideoContentDescription*>(
            video_content->description);
    UpdateRemoteStreamsList(desc->streams(), desc->type(), new_streams);
    remote_info_.default_video_track_needed =
        desc->direction() == cricket::MD_SENDRECV && desc->streams().empty();
  }

  // Update the DataChannels with the information from the remote peer.
  const cricket::ContentInfo* data_content = GetFirstDataContent(remote_desc);
  if (data_content) {
    const cricket::DataContentDescription* data_desc =
        static_cast<const cricket::DataContentDescription*>(
            data_content->description);
    if (talk_base::starts_with(
            data_desc->protocol().data(), cricket::kMediaProtocolRtpPrefix)) {
      UpdateRemoteRtpDataChannels(data_desc->streams());
    }
  }

  // Iterate new_streams and notify the observer about new MediaStreams.
  for (size_t i = 0; i < new_streams->count(); ++i) {
    MediaStreamInterface* new_stream = new_streams->at(i);
    stream_observer_->OnAddRemoteStream(new_stream);
  }

  // Find removed MediaStreams.
  if (remote_info_.IsDefaultMediaStreamNeeded() &&
      remote_streams_->find(kDefaultStreamLabel) != NULL) {
    // The default media stream already exists. No need to do anything.
  } else {
    UpdateEndedRemoteMediaStreams();
    remote_info_.msid_supported |= remote_streams_->count() > 0;
  }
  MaybeCreateDefaultStream();
}

void MediaStreamSignaling::OnLocalDescriptionChanged(
    const SessionDescriptionInterface* desc) {
  const cricket::ContentInfo* audio_content =
      GetFirstAudioContent(desc->description());
  if (audio_content) {
    if (audio_content->rejected) {
      RejectRemoteTracks(cricket::MEDIA_TYPE_AUDIO);
    }
    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) {
      RejectRemoteTracks(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 =
        static_cast<const cricket::DataContentDescription*>(
            data_content->description);
    if (talk_base::starts_with(
            data_desc->protocol().data(), cricket::kMediaProtocolRtpPrefix)) {
      UpdateLocalRtpDataChannels(data_desc->streams());
    }
  }
}

void MediaStreamSignaling::OnAudioChannelClose() {
  RejectRemoteTracks(cricket::MEDIA_TYPE_AUDIO);
}

void MediaStreamSignaling::OnVideoChannelClose() {
  RejectRemoteTracks(cricket::MEDIA_TYPE_VIDEO);
}

void MediaStreamSignaling::OnDataChannelClose() {
  DataChannels::iterator it = data_channels_.begin();
  for (; it != data_channels_.end(); ++it) {
    DataChannel* data_channel = it->second;
    data_channel->OnDataEngineClose();
  }
}

bool MediaStreamSignaling::GetRemoteAudioTrackSsrc(
    const std::string& track_id, uint32* ssrc) const {
  TrackInfos::const_iterator it = remote_audio_tracks_.find(track_id);
  if (it == remote_audio_tracks_.end()) {
    return false;
  }

  *ssrc = it->second.ssrc;
  return true;
}

bool MediaStreamSignaling::GetRemoteVideoTrackSsrc(
    const std::string& track_id, uint32* ssrc) const {
  TrackInfos::const_iterator it = remote_video_tracks_.find(track_id);
  if (it == remote_video_tracks_.end()) {
    return false;
  }

  *ssrc = it->second.ssrc;
  return true;
}

void MediaStreamSignaling::UpdateSessionOptions() {
  options_.streams.clear();
  if (local_streams_ != NULL) {
    for (size_t i = 0; i < local_streams_->count(); ++i) {
      MediaStreamInterface* stream = local_streams_->at(i);

      AudioTrackVector audio_tracks(stream->GetAudioTracks());
      if (!audio_tracks.empty()) {
        options_.has_audio = true;
      }

      // For each audio track in the stream, add it to the MediaSessionOptions.
      for (size_t j = 0; j < audio_tracks.size(); ++j) {
        scoped_refptr<MediaStreamTrackInterface> track(audio_tracks[j]);
        options_.AddStream(cricket::MEDIA_TYPE_AUDIO, track->id(),
                           stream->label());
      }

      VideoTrackVector video_tracks(stream->GetVideoTracks());
      if (!video_tracks.empty()) {
        options_.has_video = true;
      }
      // For each video track in the stream, add it to the MediaSessionOptions.
      for (size_t j = 0; j < video_tracks.size(); ++j) {
        scoped_refptr<MediaStreamTrackInterface> track(video_tracks[j]);
        options_.AddStream(cricket::MEDIA_TYPE_VIDEO, track->id(),
                           stream->label());
      }
    }
  }

  // Check for data channels.
  DataChannels::const_iterator data_channel_it = data_channels_.begin();
  for (; data_channel_it != data_channels_.end(); ++data_channel_it) {
    const DataChannel* channel = data_channel_it->second;
    if (channel->state() == DataChannel::kConnecting ||
        channel->state() == DataChannel::kOpen) {
      // |streamid| and |sync_label| are both set to the DataChannel label
      // here so they can be signaled the same way as MediaStreams and Tracks.
      // For MediaStreams, the sync_label is the MediaStream label and the
      // track label is the same as |streamid|.
      const std::string& streamid = channel->label();
      const std::string& sync_label = channel->label();
      options_.AddStream(cricket::MEDIA_TYPE_DATA, streamid, sync_label);
    }
  }
}

void MediaStreamSignaling::UpdateRemoteStreamsList(
    const cricket::StreamParamsVec& streams,
    cricket::MediaType media_type,
    StreamCollection* new_streams) {
  TrackInfos* current_tracks = GetRemoteTracks(media_type);

  // Find removed tracks. Ie tracks where the track id or ssrc don't match the
  // new StreamParam.
  TrackInfos::iterator track_it = current_tracks->begin();
  while (track_it != current_tracks->end()) {
    TrackInfo info = track_it->second;
    cricket::StreamParams params;
    if (!cricket::GetStreamBySsrc(streams, info.ssrc, &params) ||
        params.id != info.track_id) {
      OnRemoteTrackRemoved(info.stream_label, info.track_id, media_type);
      current_tracks->erase(track_it++);
    } else {
      ++track_it;
    }
  }

  // Find new and active tracks.
  for (cricket::StreamParamsVec::const_iterator it = streams.begin();
       it != streams.end(); ++it) {
    // The sync_label is the MediaStream label and the |stream.id| is the
    // track id.
    const std::string& stream_label = it->sync_label;
    const std::string& track_id = it->id;
    uint32 ssrc = it->first_ssrc();

    talk_base::scoped_refptr<MediaStreamInterface> stream =
        remote_streams_->find(stream_label);
    if (!stream) {
      // This is a new MediaStream. Create a new remote MediaStream.
      stream = remote_stream_factory_->CreateMediaStream(stream_label);
      remote_streams_->AddStream(stream);
      new_streams->AddStream(stream);
    }

    TrackInfos::iterator track_it = current_tracks->find(track_id);
    if (track_it == current_tracks->end()) {
      (*current_tracks)[track_id] =
          TrackInfo(stream_label, track_id, ssrc);
      OnRemoteTrackSeen(stream_label, track_id, it->first_ssrc(), media_type);
    }
  }
}

void MediaStreamSignaling::OnRemoteTrackSeen(const std::string& stream_label,
                                             const std::string& track_id,
                                             uint32 ssrc,
                                             cricket::MediaType media_type) {
  MediaStreamInterface* stream = remote_streams_->find(stream_label);

  if (media_type == cricket::MEDIA_TYPE_AUDIO) {
    AudioTrackInterface* audio_track =
        remote_stream_factory_->AddAudioTrack(stream, track_id);
    stream_observer_->OnAddRemoteAudioTrack(stream, audio_track, ssrc);
  } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
    VideoTrackInterface* video_track =
        remote_stream_factory_->AddVideoTrack(stream, track_id);
    stream_observer_->OnAddRemoteVideoTrack(stream, video_track, ssrc);
  } else {
    ASSERT(false && "Invalid media type");
  }
}

void MediaStreamSignaling::OnRemoteTrackRemoved(
    const std::string& stream_label,
    const std::string& track_id,
    cricket::MediaType media_type) {
  MediaStreamInterface* stream = remote_streams_->find(stream_label);

  if (media_type == cricket::MEDIA_TYPE_AUDIO) {
    talk_base::scoped_refptr<AudioTrackInterface> audio_track =
        stream->FindAudioTrack(track_id);
    if (audio_track) {
      audio_track->set_state(webrtc::MediaStreamTrackInterface::kEnded);
      stream->RemoveTrack(audio_track);
      stream_observer_->OnRemoveRemoteAudioTrack(stream, audio_track);
    }
  } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
    talk_base::scoped_refptr<VideoTrackInterface> video_track =
        stream->FindVideoTrack(track_id);
    if (video_track) {
      video_track->set_state(webrtc::MediaStreamTrackInterface::kEnded);
      stream->RemoveTrack(video_track);
      stream_observer_->OnRemoveRemoteVideoTrack(stream, video_track);
    }
  } else {
    ASSERT(false && "Invalid media type");
  }
}

void MediaStreamSignaling::RejectRemoteTracks(cricket::MediaType media_type) {
  TrackInfos* current_tracks = GetRemoteTracks(media_type);
  for (TrackInfos::iterator track_it = current_tracks->begin();
       track_it != current_tracks->end(); ++track_it) {
    TrackInfo info = track_it->second;
    MediaStreamInterface* stream = remote_streams_->find(info.stream_label);
    if (media_type == cricket::MEDIA_TYPE_AUDIO) {
      AudioTrackInterface* track = stream->FindAudioTrack(info.track_id);
      // There's no guarantee the track is still available, e.g. the track may
      // have been removed from the stream by javascript.
      if (track) {
        track->set_state(webrtc::MediaStreamTrackInterface::kEnded);
      }
    }
    if (media_type == cricket::MEDIA_TYPE_VIDEO) {
      VideoTrackInterface* track = stream->FindVideoTrack(info.track_id);
      // There's no guarantee the track is still available, e.g. the track may
      // have been removed from the stream by javascript.
      if (track) {
        track->set_state(webrtc::MediaStreamTrackInterface::kEnded);
      }
    }
  }
}

void MediaStreamSignaling::UpdateEndedRemoteMediaStreams() {
  std::vector<scoped_refptr<MediaStreamInterface> > streams_to_remove;
  for (size_t i = 0; i < remote_streams_->count(); ++i) {
    MediaStreamInterface*stream = remote_streams_->at(i);
    if (stream->GetAudioTracks().empty() && stream->GetVideoTracks().empty()) {
      streams_to_remove.push_back(stream);
    }
  }

  std::vector<scoped_refptr<MediaStreamInterface> >::const_iterator it;
  for (it = streams_to_remove.begin(); it != streams_to_remove.end(); ++it) {
    remote_streams_->RemoveStream(*it);
    stream_observer_->OnRemoveRemoteStream(*it);
  }
}

void MediaStreamSignaling::MaybeCreateDefaultStream() {
  if (!remote_info_.IsDefaultMediaStreamNeeded())
    return;

  bool default_created = false;

  scoped_refptr<MediaStreamInterface> default_remote_stream =
      remote_streams_->find(kDefaultStreamLabel);
  if (default_remote_stream == NULL) {
    default_created = true;
    default_remote_stream =
        remote_stream_factory_->CreateMediaStream(kDefaultStreamLabel);
    remote_streams_->AddStream(default_remote_stream);
  }
  if (remote_info_.default_audio_track_needed &&
      default_remote_stream->GetAudioTracks().size() == 0) {
    remote_audio_tracks_[kDefaultAudioTrackLabel] =
        TrackInfo(kDefaultStreamLabel, kDefaultAudioTrackLabel, 0);
    OnRemoteTrackSeen(kDefaultStreamLabel, kDefaultAudioTrackLabel, 0,
                       cricket::MEDIA_TYPE_AUDIO);
  }
  if (remote_info_.default_video_track_needed &&
      default_remote_stream->GetVideoTracks().size() == 0) {
    remote_video_tracks_[kDefaultVideoTrackLabel] =
        TrackInfo(kDefaultStreamLabel, kDefaultVideoTrackLabel, 0);
    OnRemoteTrackSeen(kDefaultStreamLabel, kDefaultVideoTrackLabel, 0,
                       cricket::MEDIA_TYPE_VIDEO);
  }
  if (default_created) {
    stream_observer_->OnAddRemoteStream(default_remote_stream);
  }
}

MediaStreamSignaling::TrackInfos* MediaStreamSignaling::GetRemoteTracks(
    cricket::MediaType type) {
  if (type == cricket::MEDIA_TYPE_AUDIO)
    return &remote_audio_tracks_;
  else if (type == cricket::MEDIA_TYPE_VIDEO)
    return &remote_video_tracks_;
  ASSERT(false && "Unknown MediaType");
  return NULL;
}

MediaStreamSignaling::TrackInfos* MediaStreamSignaling::GetLocalTracks(
    cricket::MediaType media_type) {
  ASSERT(media_type == cricket::MEDIA_TYPE_AUDIO ||
         media_type == cricket::MEDIA_TYPE_VIDEO);

  return (media_type == cricket::MEDIA_TYPE_AUDIO) ?
      &local_audio_tracks_ : &local_video_tracks_;
}

void MediaStreamSignaling::UpdateLocalTracks(
    const std::vector<cricket::StreamParams>& streams,
    cricket::MediaType media_type) {
  TrackInfos* current_tracks = GetLocalTracks(media_type);

  // Find removed tracks. Ie tracks where the track id or ssrc don't match the
  // new StreamParam.
  TrackInfos::iterator track_it = current_tracks->begin();
  while (track_it != current_tracks->end()) {
    TrackInfo info = track_it->second;
    cricket::StreamParams params;
    if (!cricket::GetStreamBySsrc(streams, info.ssrc, &params) ||
        params.id != info.track_id) {
      OnLocalTrackRemoved(info.stream_label, info.track_id, media_type);
      current_tracks->erase(track_it++);
    } else {
      ++track_it;
    }
  }

  // Find new and active tracks.
  for (cricket::StreamParamsVec::const_iterator it = streams.begin();
       it != streams.end(); ++it) {
    // The sync_label is the MediaStream label and the |stream.id| is the
    // track id.
    const std::string& stream_label = it->sync_label;
    const std::string& track_id = it->id;
    uint32 ssrc = it->first_ssrc();
    TrackInfos::iterator track_it =  current_tracks->find(track_id);
    if (track_it == current_tracks->end()) {
      (*current_tracks)[track_id] =
          TrackInfo(stream_label, track_id, ssrc);
      OnLocalTrackSeen(stream_label, track_id, it->first_ssrc(),
                       media_type);
    }
  }
}

void MediaStreamSignaling::OnLocalTrackSeen(
    const std::string& stream_label,
    const std::string& track_id,
    uint32 ssrc,
    cricket::MediaType media_type) {
  MediaStreamInterface* stream = local_streams_->find(stream_label);
  if (!stream) {
    LOG(LS_WARNING) << "An unknown local MediaStream with label "
                    << stream_label <<  " has been configured.";
    return;
  }

  if (media_type == cricket::MEDIA_TYPE_AUDIO) {
    AudioTrackInterface* audio_track = stream->FindAudioTrack(track_id);
    if (!audio_track) {
      LOG(LS_WARNING) << "An unknown local AudioTrack with id , "
                      << track_id <<  " has been configured.";
      return;
    }
    stream_observer_->OnAddLocalAudioTrack(stream, audio_track, ssrc);
  } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
    VideoTrackInterface* video_track = stream->FindVideoTrack(track_id);
    if (!video_track) {
      LOG(LS_WARNING) << "An unknown local VideoTrack with id , "
                      << track_id <<  " has been configured.";
      return;
    }
    stream_observer_->OnAddLocalVideoTrack(stream, video_track, ssrc);
  } else {
    ASSERT(false && "Invalid media type");
  }
}

void MediaStreamSignaling::OnLocalTrackRemoved(
    const std::string& stream_label,
    const std::string& track_id,
    cricket::MediaType media_type) {
  MediaStreamInterface* stream = local_streams_->find(stream_label);
  if (!stream) {
    // This is the normal case. Ie RemoveLocalStream has been called and the
    // SessionDescriptions has been renegotiated.
    return;
  }
  // A track has been removed from the SessionDescription but the MediaStream
  // is still associated with MediaStreamSignaling. This only occurs if the SDP
  // doesn't match with the calls to AddLocalStream and RemoveLocalStream.

  if (media_type == cricket::MEDIA_TYPE_AUDIO) {
    AudioTrackInterface* audio_track = stream->FindAudioTrack(track_id);
    if (!audio_track) {
      return;
    }
    stream_observer_->OnRemoveLocalAudioTrack(stream, audio_track);
  } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
    VideoTrackInterface* video_track = stream->FindVideoTrack(track_id);
    if (!video_track) {
      return;
    }
    stream_observer_->OnRemoveLocalVideoTrack(stream, video_track);
  } else {
    ASSERT(false && "Invalid media type.");
  }
}

void MediaStreamSignaling::UpdateLocalRtpDataChannels(
    const cricket::StreamParamsVec& streams) {
  std::vector<std::string> existing_channels;

  // Find new and active data channels.
  for (cricket::StreamParamsVec::const_iterator it =streams.begin();
       it != streams.end(); ++it) {
    // |it->sync_label| is actually the data channel label. The reason is that
    // we use the same naming of data channels as we do for
    // MediaStreams and Tracks.
    // For MediaStreams, the sync_label is the MediaStream label and the
    // track label is the same as |streamid|.
    const std::string& channel_label = it->sync_label;
    DataChannels::iterator data_channel_it = data_channels_.find(channel_label);
    if (!VERIFY(data_channel_it != data_channels_.end())) {
      continue;
    }
    // Set the SSRC the data channel should use for sending.
    data_channel_it->second->SetSendSsrc(it->first_ssrc());
    existing_channels.push_back(data_channel_it->first);
  }

  UpdateClosingDataChannels(existing_channels, true);
}

void MediaStreamSignaling::UpdateRemoteRtpDataChannels(
    const cricket::StreamParamsVec& streams) {
  std::vector<std::string> existing_channels;

  // Find new and active data channels.
  for (cricket::StreamParamsVec::const_iterator it = streams.begin();
       it != streams.end(); ++it) {
    // The data channel label is either the mslabel or the SSRC if the mslabel
    // does not exist. Ex a=ssrc:444330170 mslabel:test1.
    std::string label = it->sync_label.empty() ?
        talk_base::ToString(it->first_ssrc()) : it->sync_label;
    DataChannels::iterator data_channel_it =
        data_channels_.find(label);
    if (data_channel_it == data_channels_.end()) {
      // This is a new data channel.
      CreateRemoteDataChannel(label, it->first_ssrc());
    } else {
      data_channel_it->second->SetReceiveSsrc(it->first_ssrc());
    }
    existing_channels.push_back(label);
  }

  UpdateClosingDataChannels(existing_channels, false);
}

void MediaStreamSignaling::UpdateClosingDataChannels(
    const std::vector<std::string>& active_channels, bool is_local_update) {
  DataChannels::iterator it = data_channels_.begin();
  while (it != data_channels_.end()) {
    DataChannel* data_channel = it->second;
    if (std::find(active_channels.begin(), active_channels.end(),
                  data_channel->label()) != active_channels.end()) {
      ++it;
      continue;
    }

    if (is_local_update)
      data_channel->SetSendSsrc(0);
    else
      data_channel->RemotePeerRequestClose();

    if (data_channel->state() == DataChannel::kClosed) {
      data_channels_.erase(it);
      it = data_channels_.begin();
    } else {
      ++it;
    }
  }
}

void MediaStreamSignaling::CreateRemoteDataChannel(const std::string& label,
                                                   uint32 remote_ssrc) {
  if (!data_channel_factory_) {
    LOG(LS_WARNING) << "Remote peer requested a DataChannel but DataChannels "
                    << "are not supported.";
    return;
  }
  scoped_refptr<DataChannel> channel(
      data_channel_factory_->CreateDataChannel(label, NULL));
  channel->SetReceiveSsrc(remote_ssrc);
  stream_observer_->OnAddDataChannel(channel);
}

void MediaStreamSignaling::OnDataTransportCreatedForSctp() {
  DataChannels::iterator it = data_channels_.begin();
  for (; it != data_channels_.end(); ++it) {
    DataChannel* data_channel = it->second;
    data_channel->OnTransportChannelCreated();
  }
}

void MediaStreamSignaling::OnDtlsRoleReadyForSctp(talk_base::SSLRole role) {
  DataChannels::iterator it = data_channels_.begin();
  for (; it != data_channels_.end(); ++it) {
    DataChannel* data_channel = it->second;
    if (data_channel->id() < 0) {
      int sid;
      if (!AllocateSctpSid(role, &sid)) {
        LOG(LS_ERROR) << "Failed to allocate SCTP sid.";
        continue;
      }
      data_channel->SetSctpSid(sid);
    }
  }
}

}  // namespace webrtc