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      1 /*
      2  * libjingle
      3  * Copyright 2012, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include "talk/app/webrtc/webrtcsession.h"
     29 
     30 #include <limits.h>
     31 
     32 #include <algorithm>
     33 #include <vector>
     34 
     35 #include "talk/app/webrtc/jsepicecandidate.h"
     36 #include "talk/app/webrtc/jsepsessiondescription.h"
     37 #include "talk/app/webrtc/mediaconstraintsinterface.h"
     38 #include "talk/app/webrtc/mediastreamsignaling.h"
     39 #include "talk/app/webrtc/peerconnectioninterface.h"
     40 #include "talk/app/webrtc/webrtcsessiondescriptionfactory.h"
     41 #include "talk/media/base/constants.h"
     42 #include "talk/media/base/videocapturer.h"
     43 #include "talk/session/media/channel.h"
     44 #include "talk/session/media/channelmanager.h"
     45 #include "talk/session/media/mediasession.h"
     46 #include "webrtc/base/basictypes.h"
     47 #include "webrtc/base/helpers.h"
     48 #include "webrtc/base/logging.h"
     49 #include "webrtc/base/stringencode.h"
     50 #include "webrtc/base/stringutils.h"
     51 
     52 using cricket::ContentInfo;
     53 using cricket::ContentInfos;
     54 using cricket::MediaContentDescription;
     55 using cricket::SessionDescription;
     56 using cricket::TransportInfo;
     57 
     58 namespace webrtc {
     59 
     60 // Error messages
     61 const char kBundleWithoutRtcpMux[] = "RTCP-MUX must be enabled when BUNDLE "
     62                                      "is enabled.";
     63 const char kCreateChannelFailed[] = "Failed to create channels.";
     64 const char kInvalidCandidates[] = "Description contains invalid candidates.";
     65 const char kInvalidSdp[] = "Invalid session description.";
     66 const char kMlineMismatch[] =
     67     "Offer and answer descriptions m-lines are not matching. Rejecting answer.";
     68 const char kPushDownTDFailed[] =
     69     "Failed to push down transport description:";
     70 const char kSdpWithoutDtlsFingerprint[] =
     71     "Called with SDP without DTLS fingerprint.";
     72 const char kSdpWithoutSdesCrypto[] =
     73     "Called with SDP without SDES crypto.";
     74 const char kSdpWithoutIceUfragPwd[] =
     75     "Called with SDP without ice-ufrag and ice-pwd.";
     76 const char kSessionError[] = "Session error code: ";
     77 const char kSessionErrorDesc[] = "Session error description: ";
     78 const int kMaxUnsignalledRecvStreams = 20;
     79 
     80 // Compares |answer| against |offer|. Comparision is done
     81 // for number of m-lines in answer against offer. If matches true will be
     82 // returned otherwise false.
     83 static bool VerifyMediaDescriptions(
     84     const SessionDescription* answer, const SessionDescription* offer) {
     85   if (offer->contents().size() != answer->contents().size())
     86     return false;
     87 
     88   for (size_t i = 0; i < offer->contents().size(); ++i) {
     89     if ((offer->contents()[i].name) != answer->contents()[i].name) {
     90       return false;
     91     }
     92     const MediaContentDescription* offer_mdesc =
     93         static_cast<const MediaContentDescription*>(
     94             offer->contents()[i].description);
     95     const MediaContentDescription* answer_mdesc =
     96         static_cast<const MediaContentDescription*>(
     97             answer->contents()[i].description);
     98     if (offer_mdesc->type() != answer_mdesc->type()) {
     99       return false;
    100     }
    101   }
    102   return true;
    103 }
    104 
    105 // Checks that each non-rejected content has SDES crypto keys or a DTLS
    106 // fingerprint. Mismatches, such as replying with a DTLS fingerprint to SDES
    107 // keys, will be caught in Transport negotiation, and backstopped by Channel's
    108 // |secure_required| check.
    109 static bool VerifyCrypto(const SessionDescription* desc,
    110                          bool dtls_enabled,
    111                          std::string* error) {
    112   const ContentInfos& contents = desc->contents();
    113   for (size_t index = 0; index < contents.size(); ++index) {
    114     const ContentInfo* cinfo = &contents[index];
    115     if (cinfo->rejected) {
    116       continue;
    117     }
    118 
    119     // If the content isn't rejected, crypto must be present.
    120     const MediaContentDescription* media =
    121         static_cast<const MediaContentDescription*>(cinfo->description);
    122     const TransportInfo* tinfo = desc->GetTransportInfoByName(cinfo->name);
    123     if (!media || !tinfo) {
    124       // Something is not right.
    125       LOG(LS_ERROR) << kInvalidSdp;
    126       *error = kInvalidSdp;
    127       return false;
    128     }
    129     if (dtls_enabled) {
    130       if (!tinfo->description.identity_fingerprint) {
    131         LOG(LS_WARNING) <<
    132             "Session description must have DTLS fingerprint if DTLS enabled.";
    133         *error = kSdpWithoutDtlsFingerprint;
    134         return false;
    135       }
    136     } else {
    137       if (media->cryptos().empty()) {
    138         LOG(LS_WARNING) <<
    139             "Session description must have SDES when DTLS disabled.";
    140         *error = kSdpWithoutSdesCrypto;
    141         return false;
    142       }
    143     }
    144   }
    145 
    146   return true;
    147 }
    148 
    149 // Checks that each non-rejected content has ice-ufrag and ice-pwd set.
    150 static bool VerifyIceUfragPwdPresent(const SessionDescription* desc) {
    151   const ContentInfos& contents = desc->contents();
    152   for (size_t index = 0; index < contents.size(); ++index) {
    153     const ContentInfo* cinfo = &contents[index];
    154     if (cinfo->rejected) {
    155       continue;
    156     }
    157 
    158     // If the content isn't rejected, ice-ufrag and ice-pwd must be present.
    159     const TransportInfo* tinfo = desc->GetTransportInfoByName(cinfo->name);
    160     if (!tinfo) {
    161       // Something is not right.
    162       LOG(LS_ERROR) << kInvalidSdp;
    163       return false;
    164     }
    165     if (tinfo->description.ice_ufrag.empty() ||
    166         tinfo->description.ice_pwd.empty()) {
    167       LOG(LS_ERROR) << "Session description must have ice ufrag and pwd.";
    168       return false;
    169     }
    170   }
    171   return true;
    172 }
    173 
    174 // Forces |sdesc->crypto_required| to the appropriate state based on the
    175 // current security policy, to ensure a failure occurs if there is an error
    176 // in crypto negotiation.
    177 // Called when processing the local session description.
    178 static void UpdateSessionDescriptionSecurePolicy(cricket::CryptoType type,
    179                                                  SessionDescription* sdesc) {
    180   if (!sdesc) {
    181     return;
    182   }
    183 
    184   // Updating the |crypto_required_| in MediaContentDescription to the
    185   // appropriate state based on the current security policy.
    186   for (cricket::ContentInfos::iterator iter = sdesc->contents().begin();
    187        iter != sdesc->contents().end(); ++iter) {
    188     if (cricket::IsMediaContent(&*iter)) {
    189       MediaContentDescription* mdesc =
    190           static_cast<MediaContentDescription*> (iter->description);
    191       if (mdesc) {
    192         mdesc->set_crypto_required(type);
    193       }
    194     }
    195   }
    196 }
    197 
    198 static bool GetAudioSsrcByTrackId(
    199     const SessionDescription* session_description,
    200     const std::string& track_id, uint32 *ssrc) {
    201   const cricket::ContentInfo* audio_info =
    202       cricket::GetFirstAudioContent(session_description);
    203   if (!audio_info) {
    204     LOG(LS_ERROR) << "Audio not used in this call";
    205     return false;
    206   }
    207 
    208   const cricket::MediaContentDescription* audio_content =
    209       static_cast<const cricket::MediaContentDescription*>(
    210           audio_info->description);
    211   cricket::StreamParams stream;
    212   if (!cricket::GetStreamByIds(audio_content->streams(), "", track_id,
    213                                &stream)) {
    214     return false;
    215   }
    216   *ssrc = stream.first_ssrc();
    217   return true;
    218 }
    219 
    220 static bool GetTrackIdBySsrc(const SessionDescription* session_description,
    221                              uint32 ssrc, std::string* track_id) {
    222   ASSERT(track_id != NULL);
    223 
    224   cricket::StreamParams stream_out;
    225   const cricket::ContentInfo* audio_info =
    226       cricket::GetFirstAudioContent(session_description);
    227   if (audio_info) {
    228     const cricket::MediaContentDescription* audio_content =
    229         static_cast<const cricket::MediaContentDescription*>(
    230             audio_info->description);
    231 
    232     if (cricket::GetStreamBySsrc(audio_content->streams(), ssrc, &stream_out)) {
    233       *track_id = stream_out.id;
    234       return true;
    235     }
    236   }
    237 
    238   const cricket::ContentInfo* video_info =
    239       cricket::GetFirstVideoContent(session_description);
    240   if (video_info) {
    241     const cricket::MediaContentDescription* video_content =
    242         static_cast<const cricket::MediaContentDescription*>(
    243             video_info->description);
    244 
    245     if (cricket::GetStreamBySsrc(video_content->streams(), ssrc, &stream_out)) {
    246       *track_id = stream_out.id;
    247       return true;
    248     }
    249   }
    250   return false;
    251 }
    252 
    253 static bool BadSdp(const std::string& source,
    254                    const std::string& type,
    255                    const std::string& reason,
    256                    std::string* err_desc) {
    257   std::ostringstream desc;
    258   desc << "Failed to set " << source << " " << type << " sdp: " << reason;
    259 
    260   if (err_desc) {
    261     *err_desc = desc.str();
    262   }
    263   LOG(LS_ERROR) << desc.str();
    264   return false;
    265 }
    266 
    267 static bool BadSdp(cricket::ContentSource source,
    268                    const std::string& type,
    269                    const std::string& reason,
    270                    std::string* err_desc) {
    271   if (source == cricket::CS_LOCAL) {
    272     return BadSdp("local", type, reason, err_desc);
    273   } else {
    274     return BadSdp("remote", type, reason, err_desc);
    275   }
    276 }
    277 
    278 static bool BadLocalSdp(const std::string& type,
    279                         const std::string& reason,
    280                         std::string* err_desc) {
    281   return BadSdp(cricket::CS_LOCAL, type, reason, err_desc);
    282 }
    283 
    284 static bool BadRemoteSdp(const std::string& type,
    285                          const std::string& reason,
    286                          std::string* err_desc) {
    287   return BadSdp(cricket::CS_REMOTE, type, reason, err_desc);
    288 }
    289 
    290 static bool BadOfferSdp(cricket::ContentSource source,
    291                         const std::string& reason,
    292                         std::string* err_desc) {
    293   return BadSdp(source, SessionDescriptionInterface::kOffer, reason, err_desc);
    294 }
    295 
    296 static bool BadPranswerSdp(cricket::ContentSource source,
    297                            const std::string& reason,
    298                            std::string* err_desc) {
    299   return BadSdp(source, SessionDescriptionInterface::kPrAnswer,
    300                 reason, err_desc);
    301 }
    302 
    303 static bool BadAnswerSdp(cricket::ContentSource source,
    304                          const std::string& reason,
    305                          std::string* err_desc) {
    306   return BadSdp(source, SessionDescriptionInterface::kAnswer, reason, err_desc);
    307 }
    308 
    309 #define GET_STRING_OF_STATE(state)  \
    310   case cricket::BaseSession::state:  \
    311     result = #state;  \
    312     break;
    313 
    314 static std::string GetStateString(cricket::BaseSession::State state) {
    315   std::string result;
    316   switch (state) {
    317     GET_STRING_OF_STATE(STATE_INIT)
    318     GET_STRING_OF_STATE(STATE_SENTINITIATE)
    319     GET_STRING_OF_STATE(STATE_RECEIVEDINITIATE)
    320     GET_STRING_OF_STATE(STATE_SENTPRACCEPT)
    321     GET_STRING_OF_STATE(STATE_SENTACCEPT)
    322     GET_STRING_OF_STATE(STATE_RECEIVEDPRACCEPT)
    323     GET_STRING_OF_STATE(STATE_RECEIVEDACCEPT)
    324     GET_STRING_OF_STATE(STATE_SENTMODIFY)
    325     GET_STRING_OF_STATE(STATE_RECEIVEDMODIFY)
    326     GET_STRING_OF_STATE(STATE_SENTREJECT)
    327     GET_STRING_OF_STATE(STATE_RECEIVEDREJECT)
    328     GET_STRING_OF_STATE(STATE_SENTREDIRECT)
    329     GET_STRING_OF_STATE(STATE_SENTTERMINATE)
    330     GET_STRING_OF_STATE(STATE_RECEIVEDTERMINATE)
    331     GET_STRING_OF_STATE(STATE_INPROGRESS)
    332     GET_STRING_OF_STATE(STATE_DEINIT)
    333     default:
    334       ASSERT(false);
    335       break;
    336   }
    337   return result;
    338 }
    339 
    340 #define GET_STRING_OF_ERROR_CODE(err)  \
    341   case cricket::BaseSession::err:  \
    342     result = #err;  \
    343     break;
    344 
    345 static std::string GetErrorCodeString(cricket::BaseSession::Error err) {
    346   std::string result;
    347   switch (err) {
    348     GET_STRING_OF_ERROR_CODE(ERROR_NONE)
    349     GET_STRING_OF_ERROR_CODE(ERROR_TIME)
    350     GET_STRING_OF_ERROR_CODE(ERROR_RESPONSE)
    351     GET_STRING_OF_ERROR_CODE(ERROR_NETWORK)
    352     GET_STRING_OF_ERROR_CODE(ERROR_CONTENT)
    353     GET_STRING_OF_ERROR_CODE(ERROR_TRANSPORT)
    354     default:
    355       ASSERT(false);
    356       break;
    357   }
    358   return result;
    359 }
    360 
    361 static std::string MakeErrorString(const std::string& error,
    362                                    const std::string& desc) {
    363   std::ostringstream ret;
    364   ret << error << " " << desc;
    365   return ret.str();
    366 }
    367 
    368 static std::string MakeTdErrorString(const std::string& desc) {
    369   return MakeErrorString(kPushDownTDFailed, desc);
    370 }
    371 
    372 // Set |option| to the highest-priority value of |key| in the optional
    373 // constraints if the key is found and has a valid value.
    374 template<typename T>
    375 static void SetOptionFromOptionalConstraint(
    376     const MediaConstraintsInterface* constraints,
    377     const std::string& key, cricket::Settable<T>* option) {
    378   if (!constraints) {
    379     return;
    380   }
    381   std::string string_value;
    382   T value;
    383   if (constraints->GetOptional().FindFirst(key, &string_value)) {
    384     if (rtc::FromString(string_value, &value)) {
    385       option->Set(value);
    386     }
    387   }
    388 }
    389 
    390 uint32 ConvertIceTransportTypeToCandidateFilter(
    391     PeerConnectionInterface::IceTransportsType type) {
    392   switch (type) {
    393     case PeerConnectionInterface::kNone:
    394         return cricket::CF_NONE;
    395     case PeerConnectionInterface::kRelay:
    396         return cricket::CF_RELAY;
    397     case PeerConnectionInterface::kNoHost:
    398         return (cricket::CF_ALL & ~cricket::CF_HOST);
    399     case PeerConnectionInterface::kAll:
    400         return cricket::CF_ALL;
    401     default: ASSERT(false);
    402   }
    403   return cricket::CF_NONE;
    404 }
    405 
    406 // Help class used to remember if a a remote peer has requested ice restart by
    407 // by sending a description with new ice ufrag and password.
    408 class IceRestartAnswerLatch {
    409  public:
    410   IceRestartAnswerLatch() : ice_restart_(false) { }
    411 
    412   // Returns true if CheckForRemoteIceRestart has been called with a new session
    413   // description where ice password and ufrag has changed since last time
    414   // Reset() was called.
    415   bool Get() const {
    416     return ice_restart_;
    417   }
    418 
    419   void Reset() {
    420     if (ice_restart_) {
    421       ice_restart_ = false;
    422     }
    423   }
    424 
    425   void CheckForRemoteIceRestart(
    426       const SessionDescriptionInterface* old_desc,
    427       const SessionDescriptionInterface* new_desc) {
    428     if (!old_desc || new_desc->type() != SessionDescriptionInterface::kOffer) {
    429       return;
    430     }
    431     const SessionDescription* new_sd = new_desc->description();
    432     const SessionDescription* old_sd = old_desc->description();
    433     const ContentInfos& contents = new_sd->contents();
    434     for (size_t index = 0; index < contents.size(); ++index) {
    435       const ContentInfo* cinfo = &contents[index];
    436       if (cinfo->rejected) {
    437         continue;
    438       }
    439       // If the content isn't rejected, check if ufrag and password has
    440       // changed.
    441       const cricket::TransportDescription* new_transport_desc =
    442           new_sd->GetTransportDescriptionByName(cinfo->name);
    443       const cricket::TransportDescription* old_transport_desc =
    444           old_sd->GetTransportDescriptionByName(cinfo->name);
    445       if (!new_transport_desc || !old_transport_desc) {
    446         // No transport description exist. This is not an ice restart.
    447         continue;
    448       }
    449       if (cricket::IceCredentialsChanged(old_transport_desc->ice_ufrag,
    450                                          old_transport_desc->ice_pwd,
    451                                          new_transport_desc->ice_ufrag,
    452                                          new_transport_desc->ice_pwd)) {
    453         LOG(LS_INFO) << "Remote peer request ice restart.";
    454         ice_restart_ = true;
    455         break;
    456       }
    457     }
    458   }
    459 
    460  private:
    461   bool ice_restart_;
    462 };
    463 
    464 WebRtcSession::WebRtcSession(
    465     cricket::ChannelManager* channel_manager,
    466     rtc::Thread* signaling_thread,
    467     rtc::Thread* worker_thread,
    468     cricket::PortAllocator* port_allocator,
    469     MediaStreamSignaling* mediastream_signaling)
    470     : cricket::BaseSession(signaling_thread, worker_thread, port_allocator,
    471                            rtc::ToString(rtc::CreateRandomId64() &
    472                                                LLONG_MAX),
    473                            cricket::NS_JINGLE_RTP, false),
    474       // RFC 3264: The numeric value of the session id and version in the
    475       // o line MUST be representable with a "64 bit signed integer".
    476       // Due to this constraint session id |sid_| is max limited to LLONG_MAX.
    477       channel_manager_(channel_manager),
    478       mediastream_signaling_(mediastream_signaling),
    479       ice_observer_(NULL),
    480       ice_connection_state_(PeerConnectionInterface::kIceConnectionNew),
    481       older_version_remote_peer_(false),
    482       dtls_enabled_(false),
    483       data_channel_type_(cricket::DCT_NONE),
    484       ice_restart_latch_(new IceRestartAnswerLatch) {
    485 }
    486 
    487 WebRtcSession::~WebRtcSession() {
    488   // Destroy video_channel_ first since it may have a pointer to the
    489   // voice_channel_.
    490   if (video_channel_.get()) {
    491     SignalVideoChannelDestroyed();
    492     channel_manager_->DestroyVideoChannel(video_channel_.release());
    493   }
    494   if (voice_channel_.get()) {
    495     SignalVoiceChannelDestroyed();
    496     channel_manager_->DestroyVoiceChannel(voice_channel_.release());
    497   }
    498   if (data_channel_.get()) {
    499     SignalDataChannelDestroyed();
    500     channel_manager_->DestroyDataChannel(data_channel_.release());
    501   }
    502   for (size_t i = 0; i < saved_candidates_.size(); ++i) {
    503     delete saved_candidates_[i];
    504   }
    505   delete identity();
    506 }
    507 
    508 bool WebRtcSession::Initialize(
    509     const PeerConnectionFactoryInterface::Options& options,
    510     const MediaConstraintsInterface*  constraints,
    511     DTLSIdentityServiceInterface* dtls_identity_service,
    512     PeerConnectionInterface::IceTransportsType ice_transport) {
    513   // TODO(perkj): Take |constraints| into consideration. Return false if not all
    514   // mandatory constraints can be fulfilled. Note that |constraints|
    515   // can be null.
    516   bool value;
    517 
    518   if (options.disable_encryption) {
    519     dtls_enabled_ = false;
    520   } else {
    521     // Enable DTLS by default if |dtls_identity_service| is valid.
    522     dtls_enabled_ = (dtls_identity_service != NULL);
    523     // |constraints| can override the default |dtls_enabled_| value.
    524     if (FindConstraint(
    525           constraints,
    526           MediaConstraintsInterface::kEnableDtlsSrtp,
    527           &value, NULL)) {
    528       dtls_enabled_ = value;
    529     }
    530   }
    531 
    532   // Enable creation of RTP data channels if the kEnableRtpDataChannels is set.
    533   // It takes precendence over the disable_sctp_data_channels
    534   // PeerConnectionFactoryInterface::Options.
    535   if (FindConstraint(
    536       constraints, MediaConstraintsInterface::kEnableRtpDataChannels,
    537       &value, NULL) && value) {
    538     LOG(LS_INFO) << "Allowing RTP data engine.";
    539     data_channel_type_ = cricket::DCT_RTP;
    540   } else {
    541     // DTLS has to be enabled to use SCTP.
    542     if (!options.disable_sctp_data_channels && dtls_enabled_) {
    543       LOG(LS_INFO) << "Allowing SCTP data engine.";
    544       data_channel_type_ = cricket::DCT_SCTP;
    545     }
    546   }
    547   if (data_channel_type_ != cricket::DCT_NONE) {
    548     mediastream_signaling_->SetDataChannelFactory(this);
    549   }
    550 
    551   // Find DSCP constraint.
    552   if (FindConstraint(
    553         constraints,
    554         MediaConstraintsInterface::kEnableDscp,
    555         &value, NULL)) {
    556     audio_options_.dscp.Set(value);
    557     video_options_.dscp.Set(value);
    558   }
    559 
    560   // Find Suspend Below Min Bitrate constraint.
    561   if (FindConstraint(
    562           constraints,
    563           MediaConstraintsInterface::kEnableVideoSuspendBelowMinBitrate,
    564           &value,
    565           NULL)) {
    566     video_options_.suspend_below_min_bitrate.Set(value);
    567   }
    568 
    569   SetOptionFromOptionalConstraint(constraints,
    570       MediaConstraintsInterface::kScreencastMinBitrate,
    571       &video_options_.screencast_min_bitrate);
    572 
    573   // Find constraints for cpu overuse detection.
    574   SetOptionFromOptionalConstraint(constraints,
    575       MediaConstraintsInterface::kCpuUnderuseThreshold,
    576       &video_options_.cpu_underuse_threshold);
    577   SetOptionFromOptionalConstraint(constraints,
    578       MediaConstraintsInterface::kCpuOveruseThreshold,
    579       &video_options_.cpu_overuse_threshold);
    580   SetOptionFromOptionalConstraint(constraints,
    581       MediaConstraintsInterface::kCpuOveruseDetection,
    582       &video_options_.cpu_overuse_detection);
    583   SetOptionFromOptionalConstraint(constraints,
    584       MediaConstraintsInterface::kCpuOveruseEncodeUsage,
    585       &video_options_.cpu_overuse_encode_usage);
    586   SetOptionFromOptionalConstraint(constraints,
    587       MediaConstraintsInterface::kCpuUnderuseEncodeRsdThreshold,
    588       &video_options_.cpu_underuse_encode_rsd_threshold);
    589   SetOptionFromOptionalConstraint(constraints,
    590       MediaConstraintsInterface::kCpuOveruseEncodeRsdThreshold,
    591       &video_options_.cpu_overuse_encode_rsd_threshold);
    592 
    593   // Find payload padding constraint.
    594   SetOptionFromOptionalConstraint(constraints,
    595       MediaConstraintsInterface::kPayloadPadding,
    596       &video_options_.use_payload_padding);
    597 
    598   SetOptionFromOptionalConstraint(constraints,
    599       MediaConstraintsInterface::kNumUnsignalledRecvStreams,
    600       &video_options_.unsignalled_recv_stream_limit);
    601   if (video_options_.unsignalled_recv_stream_limit.IsSet()) {
    602     int stream_limit;
    603     video_options_.unsignalled_recv_stream_limit.Get(&stream_limit);
    604     stream_limit = rtc::_min(kMaxUnsignalledRecvStreams, stream_limit);
    605     stream_limit = rtc::_max(0, stream_limit);
    606     video_options_.unsignalled_recv_stream_limit.Set(stream_limit);
    607   }
    608 
    609   SetOptionFromOptionalConstraint(constraints,
    610       MediaConstraintsInterface::kHighStartBitrate,
    611       &video_options_.video_start_bitrate);
    612 
    613   if (FindConstraint(
    614       constraints,
    615       MediaConstraintsInterface::kVeryHighBitrate,
    616       &value,
    617       NULL)) {
    618     video_options_.video_highest_bitrate.Set(
    619         cricket::VideoOptions::VERY_HIGH);
    620   } else if (FindConstraint(
    621       constraints,
    622       MediaConstraintsInterface::kHighBitrate,
    623       &value,
    624       NULL)) {
    625     video_options_.video_highest_bitrate.Set(
    626         cricket::VideoOptions::HIGH);
    627   }
    628 
    629   SetOptionFromOptionalConstraint(constraints,
    630       MediaConstraintsInterface::kCombinedAudioVideoBwe,
    631       &audio_options_.combined_audio_video_bwe);
    632 
    633   const cricket::VideoCodec default_codec(
    634       JsepSessionDescription::kDefaultVideoCodecId,
    635       JsepSessionDescription::kDefaultVideoCodecName,
    636       JsepSessionDescription::kMaxVideoCodecWidth,
    637       JsepSessionDescription::kMaxVideoCodecHeight,
    638       JsepSessionDescription::kDefaultVideoCodecFramerate,
    639       JsepSessionDescription::kDefaultVideoCodecPreference);
    640   channel_manager_->SetDefaultVideoEncoderConfig(
    641       cricket::VideoEncoderConfig(default_codec));
    642 
    643   webrtc_session_desc_factory_.reset(new WebRtcSessionDescriptionFactory(
    644       signaling_thread(),
    645       channel_manager_,
    646       mediastream_signaling_,
    647       dtls_identity_service,
    648       this,
    649       id(),
    650       data_channel_type_,
    651       dtls_enabled_));
    652 
    653   webrtc_session_desc_factory_->SignalIdentityReady.connect(
    654       this, &WebRtcSession::OnIdentityReady);
    655 
    656   if (options.disable_encryption) {
    657     webrtc_session_desc_factory_->SetSdesPolicy(cricket::SEC_DISABLED);
    658   }
    659   port_allocator()->set_candidate_filter(
    660       ConvertIceTransportTypeToCandidateFilter(ice_transport));
    661   return true;
    662 }
    663 
    664 void WebRtcSession::Terminate() {
    665   SetState(STATE_RECEIVEDTERMINATE);
    666   RemoveUnusedChannelsAndTransports(NULL);
    667   ASSERT(voice_channel_.get() == NULL);
    668   ASSERT(video_channel_.get() == NULL);
    669   ASSERT(data_channel_.get() == NULL);
    670 }
    671 
    672 bool WebRtcSession::StartCandidatesAllocation() {
    673   // SpeculativelyConnectTransportChannels, will call ConnectChannels method
    674   // from TransportProxy to start gathering ice candidates.
    675   SpeculativelyConnectAllTransportChannels();
    676   if (!saved_candidates_.empty()) {
    677     // If there are saved candidates which arrived before local description is
    678     // set, copy those to remote description.
    679     CopySavedCandidates(remote_desc_.get());
    680   }
    681   // Push remote candidates present in remote description to transport channels.
    682   UseCandidatesInSessionDescription(remote_desc_.get());
    683   return true;
    684 }
    685 
    686 void WebRtcSession::SetSdesPolicy(cricket::SecurePolicy secure_policy) {
    687   webrtc_session_desc_factory_->SetSdesPolicy(secure_policy);
    688 }
    689 
    690 cricket::SecurePolicy WebRtcSession::SdesPolicy() const {
    691   return webrtc_session_desc_factory_->SdesPolicy();
    692 }
    693 
    694 bool WebRtcSession::GetSslRole(rtc::SSLRole* role) {
    695   if (local_description() == NULL || remote_description() == NULL) {
    696     LOG(LS_INFO) << "Local and Remote descriptions must be applied to get "
    697                  << "SSL Role of the session.";
    698     return false;
    699   }
    700 
    701   // TODO(mallinath) - Return role of each transport, as role may differ from
    702   // one another.
    703   // In current implementaion we just return the role of first transport in the
    704   // transport map.
    705   for (cricket::TransportMap::const_iterator iter = transport_proxies().begin();
    706        iter != transport_proxies().end(); ++iter) {
    707     if (iter->second->impl()) {
    708       return iter->second->impl()->GetSslRole(role);
    709     }
    710   }
    711   return false;
    712 }
    713 
    714 void WebRtcSession::CreateOffer(
    715     CreateSessionDescriptionObserver* observer,
    716     const PeerConnectionInterface::RTCOfferAnswerOptions& options) {
    717   webrtc_session_desc_factory_->CreateOffer(observer, options);
    718 }
    719 
    720 void WebRtcSession::CreateAnswer(CreateSessionDescriptionObserver* observer,
    721                                  const MediaConstraintsInterface* constraints) {
    722   webrtc_session_desc_factory_->CreateAnswer(observer, constraints);
    723 }
    724 
    725 bool WebRtcSession::SetLocalDescription(SessionDescriptionInterface* desc,
    726                                         std::string* err_desc) {
    727   // Takes the ownership of |desc| regardless of the result.
    728   rtc::scoped_ptr<SessionDescriptionInterface> desc_temp(desc);
    729 
    730   // Validate SDP.
    731   if (!ValidateSessionDescription(desc, cricket::CS_LOCAL, err_desc)) {
    732     return false;
    733   }
    734 
    735   // Update the initiator flag if this session is the initiator.
    736   Action action = GetAction(desc->type());
    737   if (state() == STATE_INIT && action == kOffer) {
    738     set_initiator(true);
    739   }
    740 
    741   cricket::SecurePolicy sdes_policy =
    742       webrtc_session_desc_factory_->SdesPolicy();
    743   cricket::CryptoType crypto_required = dtls_enabled_ ?
    744       cricket::CT_DTLS : (sdes_policy == cricket::SEC_REQUIRED ?
    745           cricket::CT_SDES : cricket::CT_NONE);
    746   // Update the MediaContentDescription crypto settings as per the policy set.
    747   UpdateSessionDescriptionSecurePolicy(crypto_required, desc->description());
    748 
    749   set_local_description(desc->description()->Copy());
    750   local_desc_.reset(desc_temp.release());
    751 
    752   // Transport and Media channels will be created only when offer is set.
    753   if (action == kOffer && !CreateChannels(local_desc_->description())) {
    754     // TODO(mallinath) - Handle CreateChannel failure, as new local description
    755     // is applied. Restore back to old description.
    756     return BadLocalSdp(desc->type(), kCreateChannelFailed, err_desc);
    757   }
    758 
    759   // Remove channel and transport proxies, if MediaContentDescription is
    760   // rejected.
    761   RemoveUnusedChannelsAndTransports(local_desc_->description());
    762 
    763   if (!UpdateSessionState(action, cricket::CS_LOCAL, err_desc)) {
    764     return false;
    765   }
    766 
    767   // Kick starting the ice candidates allocation.
    768   StartCandidatesAllocation();
    769 
    770   // Update state and SSRC of local MediaStreams and DataChannels based on the
    771   // local session description.
    772   mediastream_signaling_->OnLocalDescriptionChanged(local_desc_.get());
    773 
    774   rtc::SSLRole role;
    775   if (data_channel_type_ == cricket::DCT_SCTP && GetSslRole(&role)) {
    776     mediastream_signaling_->OnDtlsRoleReadyForSctp(role);
    777   }
    778   if (error() != cricket::BaseSession::ERROR_NONE) {
    779     return BadLocalSdp(desc->type(), GetSessionErrorMsg(), err_desc);
    780   }
    781   return true;
    782 }
    783 
    784 bool WebRtcSession::SetRemoteDescription(SessionDescriptionInterface* desc,
    785                                          std::string* err_desc) {
    786   // Takes the ownership of |desc| regardless of the result.
    787   rtc::scoped_ptr<SessionDescriptionInterface> desc_temp(desc);
    788 
    789   // Validate SDP.
    790   if (!ValidateSessionDescription(desc, cricket::CS_REMOTE, err_desc)) {
    791     return false;
    792   }
    793 
    794   // Transport and Media channels will be created only when offer is set.
    795   Action action = GetAction(desc->type());
    796   if (action == kOffer && !CreateChannels(desc->description())) {
    797     // TODO(mallinath) - Handle CreateChannel failure, as new local description
    798     // is applied. Restore back to old description.
    799     return BadRemoteSdp(desc->type(), kCreateChannelFailed, err_desc);
    800   }
    801 
    802   // Remove channel and transport proxies, if MediaContentDescription is
    803   // rejected.
    804   RemoveUnusedChannelsAndTransports(desc->description());
    805 
    806   // NOTE: Candidates allocation will be initiated only when SetLocalDescription
    807   // is called.
    808   set_remote_description(desc->description()->Copy());
    809   if (!UpdateSessionState(action, cricket::CS_REMOTE, err_desc)) {
    810     return false;
    811   }
    812 
    813   // Update remote MediaStreams.
    814   mediastream_signaling_->OnRemoteDescriptionChanged(desc);
    815   if (local_description() && !UseCandidatesInSessionDescription(desc)) {
    816     return BadRemoteSdp(desc->type(), kInvalidCandidates, err_desc);
    817   }
    818 
    819   // Copy all saved candidates.
    820   CopySavedCandidates(desc);
    821   // We retain all received candidates.
    822   WebRtcSessionDescriptionFactory::CopyCandidatesFromSessionDescription(
    823       remote_desc_.get(), desc);
    824   // Check if this new SessionDescription contains new ice ufrag and password
    825   // that indicates the remote peer requests ice restart.
    826   ice_restart_latch_->CheckForRemoteIceRestart(remote_desc_.get(),
    827                                                desc);
    828   remote_desc_.reset(desc_temp.release());
    829 
    830   rtc::SSLRole role;
    831   if (data_channel_type_ == cricket::DCT_SCTP && GetSslRole(&role)) {
    832     mediastream_signaling_->OnDtlsRoleReadyForSctp(role);
    833   }
    834 
    835   if (error() != cricket::BaseSession::ERROR_NONE) {
    836     return BadRemoteSdp(desc->type(), GetSessionErrorMsg(), err_desc);
    837   }
    838   return true;
    839 }
    840 
    841 bool WebRtcSession::UpdateSessionState(
    842     Action action, cricket::ContentSource source,
    843     std::string* err_desc) {
    844   // If there's already a pending error then no state transition should happen.
    845   // But all call-sites should be verifying this before calling us!
    846   ASSERT(error() == cricket::BaseSession::ERROR_NONE);
    847   std::string td_err;
    848   if (action == kOffer) {
    849     if (!PushdownTransportDescription(source, cricket::CA_OFFER, &td_err)) {
    850       return BadOfferSdp(source, MakeTdErrorString(td_err), err_desc);
    851     }
    852     SetState(source == cricket::CS_LOCAL ?
    853         STATE_SENTINITIATE : STATE_RECEIVEDINITIATE);
    854     if (error() != cricket::BaseSession::ERROR_NONE) {
    855       return BadOfferSdp(source, GetSessionErrorMsg(), err_desc);
    856     }
    857   } else if (action == kPrAnswer) {
    858     if (!PushdownTransportDescription(source, cricket::CA_PRANSWER, &td_err)) {
    859       return BadPranswerSdp(source, MakeTdErrorString(td_err), err_desc);
    860     }
    861     EnableChannels();
    862     SetState(source == cricket::CS_LOCAL ?
    863         STATE_SENTPRACCEPT : STATE_RECEIVEDPRACCEPT);
    864     if (error() != cricket::BaseSession::ERROR_NONE) {
    865       return BadPranswerSdp(source, GetSessionErrorMsg(), err_desc);
    866     }
    867   } else if (action == kAnswer) {
    868     if (!PushdownTransportDescription(source, cricket::CA_ANSWER, &td_err)) {
    869       return BadAnswerSdp(source, MakeTdErrorString(td_err), err_desc);
    870     }
    871     MaybeEnableMuxingSupport();
    872     EnableChannels();
    873     SetState(source == cricket::CS_LOCAL ?
    874         STATE_SENTACCEPT : STATE_RECEIVEDACCEPT);
    875     if (error() != cricket::BaseSession::ERROR_NONE) {
    876       return BadAnswerSdp(source, GetSessionErrorMsg(), err_desc);
    877     }
    878   }
    879   return true;
    880 }
    881 
    882 WebRtcSession::Action WebRtcSession::GetAction(const std::string& type) {
    883   if (type == SessionDescriptionInterface::kOffer) {
    884     return WebRtcSession::kOffer;
    885   } else if (type == SessionDescriptionInterface::kPrAnswer) {
    886     return WebRtcSession::kPrAnswer;
    887   } else if (type == SessionDescriptionInterface::kAnswer) {
    888     return WebRtcSession::kAnswer;
    889   }
    890   ASSERT(false && "unknown action type");
    891   return WebRtcSession::kOffer;
    892 }
    893 
    894 bool WebRtcSession::ProcessIceMessage(const IceCandidateInterface* candidate) {
    895   if (state() == STATE_INIT) {
    896      LOG(LS_ERROR) << "ProcessIceMessage: ICE candidates can't be added "
    897                    << "without any offer (local or remote) "
    898                    << "session description.";
    899      return false;
    900   }
    901 
    902   if (!candidate) {
    903     LOG(LS_ERROR) << "ProcessIceMessage: Candidate is NULL";
    904     return false;
    905   }
    906 
    907   bool valid = false;
    908   if (!ReadyToUseRemoteCandidate(candidate, NULL, &valid)) {
    909     if (valid) {
    910       LOG(LS_INFO) << "ProcessIceMessage: Candidate saved";
    911       saved_candidates_.push_back(
    912           new JsepIceCandidate(candidate->sdp_mid(),
    913                                candidate->sdp_mline_index(),
    914                                candidate->candidate()));
    915     }
    916     return valid;
    917   }
    918 
    919   // Add this candidate to the remote session description.
    920   if (!remote_desc_->AddCandidate(candidate)) {
    921     LOG(LS_ERROR) << "ProcessIceMessage: Candidate cannot be used";
    922     return false;
    923   }
    924 
    925   return UseCandidate(candidate);
    926 }
    927 
    928 bool WebRtcSession::SetIceTransports(
    929     PeerConnectionInterface::IceTransportsType type) {
    930   return port_allocator()->set_candidate_filter(
    931         ConvertIceTransportTypeToCandidateFilter(type));
    932 }
    933 
    934 bool WebRtcSession::GetLocalTrackIdBySsrc(uint32 ssrc, std::string* track_id) {
    935   if (!BaseSession::local_description())
    936     return false;
    937   return webrtc::GetTrackIdBySsrc(
    938       BaseSession::local_description(), ssrc, track_id);
    939 }
    940 
    941 bool WebRtcSession::GetRemoteTrackIdBySsrc(uint32 ssrc, std::string* track_id) {
    942   if (!BaseSession::remote_description())
    943     return false;
    944   return webrtc::GetTrackIdBySsrc(
    945       BaseSession::remote_description(), ssrc, track_id);
    946 }
    947 
    948 std::string WebRtcSession::BadStateErrMsg(State state) {
    949   std::ostringstream desc;
    950   desc << "Called in wrong state: " << GetStateString(state);
    951   return desc.str();
    952 }
    953 
    954 void WebRtcSession::SetAudioPlayout(uint32 ssrc, bool enable,
    955                                     cricket::AudioRenderer* renderer) {
    956   ASSERT(signaling_thread()->IsCurrent());
    957   if (!voice_channel_) {
    958     LOG(LS_ERROR) << "SetAudioPlayout: No audio channel exists.";
    959     return;
    960   }
    961   if (!voice_channel_->SetRemoteRenderer(ssrc, renderer)) {
    962     // SetRenderer() can fail if the ssrc does not match any playout channel.
    963     LOG(LS_ERROR) << "SetAudioPlayout: ssrc is incorrect: " << ssrc;
    964     return;
    965   }
    966   if (!voice_channel_->SetOutputScaling(ssrc, enable ? 1 : 0, enable ? 1 : 0)) {
    967     // Allow that SetOutputScaling fail if |enable| is false but assert
    968     // otherwise. This in the normal case when the underlying media channel has
    969     // already been deleted.
    970     ASSERT(enable == false);
    971   }
    972 }
    973 
    974 void WebRtcSession::SetAudioSend(uint32 ssrc, bool enable,
    975                                  const cricket::AudioOptions& options,
    976                                  cricket::AudioRenderer* renderer) {
    977   ASSERT(signaling_thread()->IsCurrent());
    978   if (!voice_channel_) {
    979     LOG(LS_ERROR) << "SetAudioSend: No audio channel exists.";
    980     return;
    981   }
    982   if (!voice_channel_->SetLocalRenderer(ssrc, renderer)) {
    983     // SetRenderer() can fail if the ssrc does not match any send channel.
    984     LOG(LS_ERROR) << "SetAudioSend: ssrc is incorrect: " << ssrc;
    985     return;
    986   }
    987   if (!voice_channel_->MuteStream(ssrc, !enable)) {
    988     // Allow that MuteStream fail if |enable| is false but assert otherwise.
    989     // This in the normal case when the underlying media channel has already
    990     // been deleted.
    991     ASSERT(enable == false);
    992     return;
    993   }
    994   if (enable)
    995     voice_channel_->SetChannelOptions(options);
    996 }
    997 
    998 void WebRtcSession::SetAudioPlayoutVolume(uint32 ssrc, double volume) {
    999   ASSERT(signaling_thread()->IsCurrent());
   1000   ASSERT(volume >= 0 && volume <= 10);
   1001   if (!voice_channel_) {
   1002     LOG(LS_ERROR) << "SetAudioPlayoutVolume: No audio channel exists.";
   1003     return;
   1004   }
   1005 
   1006   if (!voice_channel_->SetOutputScaling(ssrc, volume, volume))
   1007     ASSERT(false);
   1008 }
   1009 
   1010 bool WebRtcSession::SetCaptureDevice(uint32 ssrc,
   1011                                      cricket::VideoCapturer* camera) {
   1012   ASSERT(signaling_thread()->IsCurrent());
   1013 
   1014   if (!video_channel_.get()) {
   1015     // |video_channel_| doesnt't exist. Probably because the remote end doesnt't
   1016     // support video.
   1017     LOG(LS_WARNING) << "Video not used in this call.";
   1018     return false;
   1019   }
   1020   if (!video_channel_->SetCapturer(ssrc, camera)) {
   1021     // Allow that SetCapturer fail if |camera| is NULL but assert otherwise.
   1022     // This in the normal case when the underlying media channel has already
   1023     // been deleted.
   1024     ASSERT(camera == NULL);
   1025     return false;
   1026   }
   1027   return true;
   1028 }
   1029 
   1030 void WebRtcSession::SetVideoPlayout(uint32 ssrc,
   1031                                     bool enable,
   1032                                     cricket::VideoRenderer* renderer) {
   1033   ASSERT(signaling_thread()->IsCurrent());
   1034   if (!video_channel_) {
   1035     LOG(LS_WARNING) << "SetVideoPlayout: No video channel exists.";
   1036     return;
   1037   }
   1038   if (!video_channel_->SetRenderer(ssrc, enable ? renderer : NULL)) {
   1039     // Allow that SetRenderer fail if |renderer| is NULL but assert otherwise.
   1040     // This in the normal case when the underlying media channel has already
   1041     // been deleted.
   1042     ASSERT(renderer == NULL);
   1043   }
   1044 }
   1045 
   1046 void WebRtcSession::SetVideoSend(uint32 ssrc, bool enable,
   1047                                  const cricket::VideoOptions* options) {
   1048   ASSERT(signaling_thread()->IsCurrent());
   1049   if (!video_channel_) {
   1050     LOG(LS_WARNING) << "SetVideoSend: No video channel exists.";
   1051     return;
   1052   }
   1053   if (!video_channel_->MuteStream(ssrc, !enable)) {
   1054     // Allow that MuteStream fail if |enable| is false but assert otherwise.
   1055     // This in the normal case when the underlying media channel has already
   1056     // been deleted.
   1057     ASSERT(enable == false);
   1058     return;
   1059   }
   1060   if (enable && options)
   1061     video_channel_->SetChannelOptions(*options);
   1062 }
   1063 
   1064 bool WebRtcSession::CanInsertDtmf(const std::string& track_id) {
   1065   ASSERT(signaling_thread()->IsCurrent());
   1066   if (!voice_channel_) {
   1067     LOG(LS_ERROR) << "CanInsertDtmf: No audio channel exists.";
   1068     return false;
   1069   }
   1070   uint32 send_ssrc = 0;
   1071   // The Dtmf is negotiated per channel not ssrc, so we only check if the ssrc
   1072   // exists.
   1073   if (!GetAudioSsrcByTrackId(BaseSession::local_description(), track_id,
   1074                              &send_ssrc)) {
   1075     LOG(LS_ERROR) << "CanInsertDtmf: Track does not exist: " << track_id;
   1076     return false;
   1077   }
   1078   return voice_channel_->CanInsertDtmf();
   1079 }
   1080 
   1081 bool WebRtcSession::InsertDtmf(const std::string& track_id,
   1082                                int code, int duration) {
   1083   ASSERT(signaling_thread()->IsCurrent());
   1084   if (!voice_channel_) {
   1085     LOG(LS_ERROR) << "InsertDtmf: No audio channel exists.";
   1086     return false;
   1087   }
   1088   uint32 send_ssrc = 0;
   1089   if (!VERIFY(GetAudioSsrcByTrackId(BaseSession::local_description(),
   1090                                     track_id, &send_ssrc))) {
   1091     LOG(LS_ERROR) << "InsertDtmf: Track does not exist: " << track_id;
   1092     return false;
   1093   }
   1094   if (!voice_channel_->InsertDtmf(send_ssrc, code, duration,
   1095                                   cricket::DF_SEND)) {
   1096     LOG(LS_ERROR) << "Failed to insert DTMF to channel.";
   1097     return false;
   1098   }
   1099   return true;
   1100 }
   1101 
   1102 sigslot::signal0<>* WebRtcSession::GetOnDestroyedSignal() {
   1103   return &SignalVoiceChannelDestroyed;
   1104 }
   1105 
   1106 bool WebRtcSession::SendData(const cricket::SendDataParams& params,
   1107                              const rtc::Buffer& payload,
   1108                              cricket::SendDataResult* result) {
   1109   if (!data_channel_.get()) {
   1110     LOG(LS_ERROR) << "SendData called when data_channel_ is NULL.";
   1111     return false;
   1112   }
   1113   return data_channel_->SendData(params, payload, result);
   1114 }
   1115 
   1116 bool WebRtcSession::ConnectDataChannel(DataChannel* webrtc_data_channel) {
   1117   if (!data_channel_.get()) {
   1118     LOG(LS_ERROR) << "ConnectDataChannel called when data_channel_ is NULL.";
   1119     return false;
   1120   }
   1121   data_channel_->SignalReadyToSendData.connect(webrtc_data_channel,
   1122                                                &DataChannel::OnChannelReady);
   1123   data_channel_->SignalDataReceived.connect(webrtc_data_channel,
   1124                                             &DataChannel::OnDataReceived);
   1125   return true;
   1126 }
   1127 
   1128 void WebRtcSession::DisconnectDataChannel(DataChannel* webrtc_data_channel) {
   1129   if (!data_channel_.get()) {
   1130     LOG(LS_ERROR) << "DisconnectDataChannel called when data_channel_ is NULL.";
   1131     return;
   1132   }
   1133   data_channel_->SignalReadyToSendData.disconnect(webrtc_data_channel);
   1134   data_channel_->SignalDataReceived.disconnect(webrtc_data_channel);
   1135 }
   1136 
   1137 void WebRtcSession::AddSctpDataStream(uint32 sid) {
   1138   if (!data_channel_.get()) {
   1139     LOG(LS_ERROR) << "AddDataChannelStreams called when data_channel_ is NULL.";
   1140     return;
   1141   }
   1142   data_channel_->AddRecvStream(cricket::StreamParams::CreateLegacy(sid));
   1143   data_channel_->AddSendStream(cricket::StreamParams::CreateLegacy(sid));
   1144 }
   1145 
   1146 void WebRtcSession::RemoveSctpDataStream(uint32 sid) {
   1147   mediastream_signaling_->RemoveSctpDataChannel(static_cast<int>(sid));
   1148 
   1149   if (!data_channel_.get()) {
   1150     LOG(LS_ERROR) << "RemoveDataChannelStreams called when data_channel_ is "
   1151                   << "NULL.";
   1152     return;
   1153   }
   1154   data_channel_->RemoveRecvStream(sid);
   1155   data_channel_->RemoveSendStream(sid);
   1156 }
   1157 
   1158 bool WebRtcSession::ReadyToSendData() const {
   1159   return data_channel_.get() && data_channel_->ready_to_send_data();
   1160 }
   1161 
   1162 rtc::scoped_refptr<DataChannel> WebRtcSession::CreateDataChannel(
   1163     const std::string& label,
   1164     const InternalDataChannelInit* config) {
   1165   if (state() == STATE_RECEIVEDTERMINATE) {
   1166     return NULL;
   1167   }
   1168   if (data_channel_type_ == cricket::DCT_NONE) {
   1169     LOG(LS_ERROR) << "CreateDataChannel: Data is not supported in this call.";
   1170     return NULL;
   1171   }
   1172   InternalDataChannelInit new_config =
   1173       config ? (*config) : InternalDataChannelInit();
   1174   if (data_channel_type_ == cricket::DCT_SCTP) {
   1175     if (new_config.id < 0) {
   1176       rtc::SSLRole role;
   1177       if (GetSslRole(&role) &&
   1178           !mediastream_signaling_->AllocateSctpSid(role, &new_config.id)) {
   1179         LOG(LS_ERROR) << "No id can be allocated for the SCTP data channel.";
   1180         return NULL;
   1181       }
   1182     } else if (!mediastream_signaling_->IsSctpSidAvailable(new_config.id)) {
   1183       LOG(LS_ERROR) << "Failed to create a SCTP data channel "
   1184                     << "because the id is already in use or out of range.";
   1185       return NULL;
   1186     }
   1187   }
   1188 
   1189   rtc::scoped_refptr<DataChannel> channel(DataChannel::Create(
   1190       this, data_channel_type_, label, new_config));
   1191   if (channel && !mediastream_signaling_->AddDataChannel(channel))
   1192     return NULL;
   1193 
   1194   return channel;
   1195 }
   1196 
   1197 cricket::DataChannelType WebRtcSession::data_channel_type() const {
   1198   return data_channel_type_;
   1199 }
   1200 
   1201 bool WebRtcSession::IceRestartPending() const {
   1202   return ice_restart_latch_->Get();
   1203 }
   1204 
   1205 void WebRtcSession::ResetIceRestartLatch() {
   1206   ice_restart_latch_->Reset();
   1207 }
   1208 
   1209 void WebRtcSession::OnIdentityReady(rtc::SSLIdentity* identity) {
   1210   SetIdentity(identity);
   1211 }
   1212 
   1213 bool WebRtcSession::waiting_for_identity() const {
   1214   return webrtc_session_desc_factory_->waiting_for_identity();
   1215 }
   1216 
   1217 void WebRtcSession::SetIceConnectionState(
   1218       PeerConnectionInterface::IceConnectionState state) {
   1219   if (ice_connection_state_ == state) {
   1220     return;
   1221   }
   1222 
   1223   // ASSERT that the requested transition is allowed.  Note that
   1224   // WebRtcSession does not implement "kIceConnectionClosed" (that is handled
   1225   // within PeerConnection).  This switch statement should compile away when
   1226   // ASSERTs are disabled.
   1227   switch (ice_connection_state_) {
   1228     case PeerConnectionInterface::kIceConnectionNew:
   1229       ASSERT(state == PeerConnectionInterface::kIceConnectionChecking);
   1230       break;
   1231     case PeerConnectionInterface::kIceConnectionChecking:
   1232       ASSERT(state == PeerConnectionInterface::kIceConnectionFailed ||
   1233              state == PeerConnectionInterface::kIceConnectionConnected);
   1234       break;
   1235     case PeerConnectionInterface::kIceConnectionConnected:
   1236       ASSERT(state == PeerConnectionInterface::kIceConnectionDisconnected ||
   1237              state == PeerConnectionInterface::kIceConnectionChecking ||
   1238              state == PeerConnectionInterface::kIceConnectionCompleted);
   1239       break;
   1240     case PeerConnectionInterface::kIceConnectionCompleted:
   1241       ASSERT(state == PeerConnectionInterface::kIceConnectionConnected ||
   1242              state == PeerConnectionInterface::kIceConnectionDisconnected);
   1243       break;
   1244     case PeerConnectionInterface::kIceConnectionFailed:
   1245       ASSERT(state == PeerConnectionInterface::kIceConnectionNew);
   1246       break;
   1247     case PeerConnectionInterface::kIceConnectionDisconnected:
   1248       ASSERT(state == PeerConnectionInterface::kIceConnectionChecking ||
   1249              state == PeerConnectionInterface::kIceConnectionConnected ||
   1250              state == PeerConnectionInterface::kIceConnectionCompleted ||
   1251              state == PeerConnectionInterface::kIceConnectionFailed);
   1252       break;
   1253     case PeerConnectionInterface::kIceConnectionClosed:
   1254       ASSERT(false);
   1255       break;
   1256     default:
   1257       ASSERT(false);
   1258       break;
   1259   }
   1260 
   1261   ice_connection_state_ = state;
   1262   if (ice_observer_) {
   1263     ice_observer_->OnIceConnectionChange(ice_connection_state_);
   1264   }
   1265 }
   1266 
   1267 void WebRtcSession::OnTransportRequestSignaling(
   1268     cricket::Transport* transport) {
   1269   ASSERT(signaling_thread()->IsCurrent());
   1270   transport->OnSignalingReady();
   1271   if (ice_observer_) {
   1272     ice_observer_->OnIceGatheringChange(
   1273       PeerConnectionInterface::kIceGatheringGathering);
   1274   }
   1275 }
   1276 
   1277 void WebRtcSession::OnTransportConnecting(cricket::Transport* transport) {
   1278   ASSERT(signaling_thread()->IsCurrent());
   1279   // start monitoring for the write state of the transport.
   1280   OnTransportWritable(transport);
   1281 }
   1282 
   1283 void WebRtcSession::OnTransportWritable(cricket::Transport* transport) {
   1284   ASSERT(signaling_thread()->IsCurrent());
   1285   if (transport->all_channels_writable()) {
   1286     SetIceConnectionState(PeerConnectionInterface::kIceConnectionConnected);
   1287   } else if (transport->HasChannels()) {
   1288     // If the current state is Connected or Completed, then there were writable
   1289     // channels but now there are not, so the next state must be Disconnected.
   1290     if (ice_connection_state_ ==
   1291             PeerConnectionInterface::kIceConnectionConnected ||
   1292         ice_connection_state_ ==
   1293             PeerConnectionInterface::kIceConnectionCompleted) {
   1294       SetIceConnectionState(
   1295           PeerConnectionInterface::kIceConnectionDisconnected);
   1296     }
   1297   }
   1298 }
   1299 
   1300 void WebRtcSession::OnTransportCompleted(cricket::Transport* transport) {
   1301   ASSERT(signaling_thread()->IsCurrent());
   1302   SetIceConnectionState(PeerConnectionInterface::kIceConnectionCompleted);
   1303 }
   1304 
   1305 void WebRtcSession::OnTransportFailed(cricket::Transport* transport) {
   1306   ASSERT(signaling_thread()->IsCurrent());
   1307   SetIceConnectionState(PeerConnectionInterface::kIceConnectionFailed);
   1308 }
   1309 
   1310 void WebRtcSession::OnTransportProxyCandidatesReady(
   1311     cricket::TransportProxy* proxy, const cricket::Candidates& candidates) {
   1312   ASSERT(signaling_thread()->IsCurrent());
   1313   ProcessNewLocalCandidate(proxy->content_name(), candidates);
   1314 }
   1315 
   1316 void WebRtcSession::OnCandidatesAllocationDone() {
   1317   ASSERT(signaling_thread()->IsCurrent());
   1318   if (ice_observer_) {
   1319     ice_observer_->OnIceGatheringChange(
   1320       PeerConnectionInterface::kIceGatheringComplete);
   1321     ice_observer_->OnIceComplete();
   1322   }
   1323 }
   1324 
   1325 // Enabling voice and video channel.
   1326 void WebRtcSession::EnableChannels() {
   1327   if (voice_channel_ && !voice_channel_->enabled())
   1328     voice_channel_->Enable(true);
   1329 
   1330   if (video_channel_ && !video_channel_->enabled())
   1331     video_channel_->Enable(true);
   1332 
   1333   if (data_channel_.get() && !data_channel_->enabled())
   1334     data_channel_->Enable(true);
   1335 }
   1336 
   1337 void WebRtcSession::ProcessNewLocalCandidate(
   1338     const std::string& content_name,
   1339     const cricket::Candidates& candidates) {
   1340   int sdp_mline_index;
   1341   if (!GetLocalCandidateMediaIndex(content_name, &sdp_mline_index)) {
   1342     LOG(LS_ERROR) << "ProcessNewLocalCandidate: content name "
   1343                   << content_name << " not found";
   1344     return;
   1345   }
   1346 
   1347   for (cricket::Candidates::const_iterator citer = candidates.begin();
   1348       citer != candidates.end(); ++citer) {
   1349     // Use content_name as the candidate media id.
   1350     JsepIceCandidate candidate(content_name, sdp_mline_index, *citer);
   1351     if (ice_observer_) {
   1352       ice_observer_->OnIceCandidate(&candidate);
   1353     }
   1354     if (local_desc_) {
   1355       local_desc_->AddCandidate(&candidate);
   1356     }
   1357   }
   1358 }
   1359 
   1360 // Returns the media index for a local ice candidate given the content name.
   1361 bool WebRtcSession::GetLocalCandidateMediaIndex(const std::string& content_name,
   1362                                                 int* sdp_mline_index) {
   1363   if (!BaseSession::local_description() || !sdp_mline_index)
   1364     return false;
   1365 
   1366   bool content_found = false;
   1367   const ContentInfos& contents = BaseSession::local_description()->contents();
   1368   for (size_t index = 0; index < contents.size(); ++index) {
   1369     if (contents[index].name == content_name) {
   1370       *sdp_mline_index = static_cast<int>(index);
   1371       content_found = true;
   1372       break;
   1373     }
   1374   }
   1375   return content_found;
   1376 }
   1377 
   1378 bool WebRtcSession::UseCandidatesInSessionDescription(
   1379     const SessionDescriptionInterface* remote_desc) {
   1380   if (!remote_desc)
   1381     return true;
   1382   bool ret = true;
   1383 
   1384   for (size_t m = 0; m < remote_desc->number_of_mediasections(); ++m) {
   1385     const IceCandidateCollection* candidates = remote_desc->candidates(m);
   1386     for  (size_t n = 0; n < candidates->count(); ++n) {
   1387       const IceCandidateInterface* candidate = candidates->at(n);
   1388       bool valid = false;
   1389       if (!ReadyToUseRemoteCandidate(candidate, remote_desc, &valid)) {
   1390         if (valid) {
   1391           LOG(LS_INFO) << "UseCandidatesInSessionDescription: Candidate saved.";
   1392           saved_candidates_.push_back(
   1393               new JsepIceCandidate(candidate->sdp_mid(),
   1394                                    candidate->sdp_mline_index(),
   1395                                    candidate->candidate()));
   1396         }
   1397         continue;
   1398       }
   1399 
   1400       ret = UseCandidate(candidate);
   1401       if (!ret)
   1402         break;
   1403     }
   1404   }
   1405   return ret;
   1406 }
   1407 
   1408 bool WebRtcSession::UseCandidate(
   1409     const IceCandidateInterface* candidate) {
   1410 
   1411   size_t mediacontent_index = static_cast<size_t>(candidate->sdp_mline_index());
   1412   size_t remote_content_size =
   1413       BaseSession::remote_description()->contents().size();
   1414   if (mediacontent_index >= remote_content_size) {
   1415     LOG(LS_ERROR)
   1416         << "UseRemoteCandidateInSession: Invalid candidate media index.";
   1417     return false;
   1418   }
   1419 
   1420   cricket::ContentInfo content =
   1421       BaseSession::remote_description()->contents()[mediacontent_index];
   1422   std::vector<cricket::Candidate> candidates;
   1423   candidates.push_back(candidate->candidate());
   1424   // Invoking BaseSession method to handle remote candidates.
   1425   std::string error;
   1426   if (OnRemoteCandidates(content.name, candidates, &error)) {
   1427     // Candidates successfully submitted for checking.
   1428     if (ice_connection_state_ == PeerConnectionInterface::kIceConnectionNew ||
   1429         ice_connection_state_ ==
   1430             PeerConnectionInterface::kIceConnectionDisconnected) {
   1431       // If state is New, then the session has just gotten its first remote ICE
   1432       // candidates, so go to Checking.
   1433       // If state is Disconnected, the session is re-using old candidates or
   1434       // receiving additional ones, so go to Checking.
   1435       // If state is Connected, stay Connected.
   1436       // TODO(bemasc): If state is Connected, and the new candidates are for a
   1437       // newly added transport, then the state actually _should_ move to
   1438       // checking.  Add a way to distinguish that case.
   1439       SetIceConnectionState(PeerConnectionInterface::kIceConnectionChecking);
   1440     }
   1441     // TODO(bemasc): If state is Completed, go back to Connected.
   1442   } else {
   1443     if (!error.empty()) {
   1444       LOG(LS_WARNING) << error;
   1445     }
   1446   }
   1447   return true;
   1448 }
   1449 
   1450 void WebRtcSession::RemoveUnusedChannelsAndTransports(
   1451     const SessionDescription* desc) {
   1452   // Destroy video_channel_ first since it may have a pointer to the
   1453   // voice_channel_.
   1454   const cricket::ContentInfo* video_info =
   1455       cricket::GetFirstVideoContent(desc);
   1456   if ((!video_info || video_info->rejected) && video_channel_) {
   1457     mediastream_signaling_->OnVideoChannelClose();
   1458     SignalVideoChannelDestroyed();
   1459     const std::string content_name = video_channel_->content_name();
   1460     channel_manager_->DestroyVideoChannel(video_channel_.release());
   1461     DestroyTransportProxy(content_name);
   1462   }
   1463 
   1464   const cricket::ContentInfo* voice_info =
   1465       cricket::GetFirstAudioContent(desc);
   1466   if ((!voice_info || voice_info->rejected) && voice_channel_) {
   1467     mediastream_signaling_->OnAudioChannelClose();
   1468     SignalVoiceChannelDestroyed();
   1469     const std::string content_name = voice_channel_->content_name();
   1470     channel_manager_->DestroyVoiceChannel(voice_channel_.release());
   1471     DestroyTransportProxy(content_name);
   1472   }
   1473 
   1474   const cricket::ContentInfo* data_info =
   1475       cricket::GetFirstDataContent(desc);
   1476   if ((!data_info || data_info->rejected) && data_channel_) {
   1477     mediastream_signaling_->OnDataChannelClose();
   1478     SignalDataChannelDestroyed();
   1479     const std::string content_name = data_channel_->content_name();
   1480     channel_manager_->DestroyDataChannel(data_channel_.release());
   1481     DestroyTransportProxy(content_name);
   1482   }
   1483 }
   1484 
   1485 // TODO(mallinath) - Add a correct error code if the channels are not creatued
   1486 // due to BUNDLE is enabled but rtcp-mux is disabled.
   1487 bool WebRtcSession::CreateChannels(const SessionDescription* desc) {
   1488   // Disabling the BUNDLE flag in PortAllocator if offer disabled it.
   1489   bool bundle_enabled = desc->HasGroup(cricket::GROUP_TYPE_BUNDLE);
   1490   if (state() == STATE_INIT && !bundle_enabled) {
   1491     port_allocator()->set_flags(port_allocator()->flags() &
   1492                                 ~cricket::PORTALLOCATOR_ENABLE_BUNDLE);
   1493   }
   1494 
   1495   // Creating the media channels and transport proxies.
   1496   const cricket::ContentInfo* voice = cricket::GetFirstAudioContent(desc);
   1497   if (voice && !voice->rejected && !voice_channel_) {
   1498     if (!CreateVoiceChannel(voice)) {
   1499       LOG(LS_ERROR) << "Failed to create voice channel.";
   1500       return false;
   1501     }
   1502   }
   1503 
   1504   const cricket::ContentInfo* video = cricket::GetFirstVideoContent(desc);
   1505   if (video && !video->rejected && !video_channel_) {
   1506     if (!CreateVideoChannel(video)) {
   1507       LOG(LS_ERROR) << "Failed to create video channel.";
   1508       return false;
   1509     }
   1510   }
   1511 
   1512   const cricket::ContentInfo* data = cricket::GetFirstDataContent(desc);
   1513   if (data_channel_type_ != cricket::DCT_NONE &&
   1514       data && !data->rejected && !data_channel_.get()) {
   1515     if (!CreateDataChannel(data)) {
   1516       LOG(LS_ERROR) << "Failed to create data channel.";
   1517       return false;
   1518     }
   1519   }
   1520 
   1521   return true;
   1522 }
   1523 
   1524 bool WebRtcSession::CreateVoiceChannel(const cricket::ContentInfo* content) {
   1525   voice_channel_.reset(channel_manager_->CreateVoiceChannel(
   1526       this, content->name, true));
   1527   if (!voice_channel_.get())
   1528     return false;
   1529 
   1530   voice_channel_->SetChannelOptions(audio_options_);
   1531   return true;
   1532 }
   1533 
   1534 bool WebRtcSession::CreateVideoChannel(const cricket::ContentInfo* content) {
   1535   video_channel_.reset(channel_manager_->CreateVideoChannel(
   1536       this, content->name, true, voice_channel_.get()));
   1537   if (!video_channel_.get())
   1538     return false;
   1539 
   1540   video_channel_->SetChannelOptions(video_options_);
   1541   return true;
   1542 }
   1543 
   1544 bool WebRtcSession::CreateDataChannel(const cricket::ContentInfo* content) {
   1545   bool sctp = (data_channel_type_ == cricket::DCT_SCTP);
   1546   data_channel_.reset(channel_manager_->CreateDataChannel(
   1547       this, content->name, !sctp, data_channel_type_));
   1548   if (!data_channel_.get()) {
   1549     return false;
   1550   }
   1551   if (sctp) {
   1552     mediastream_signaling_->OnDataTransportCreatedForSctp();
   1553     data_channel_->SignalDataReceived.connect(
   1554         this, &WebRtcSession::OnDataChannelMessageReceived);
   1555     data_channel_->SignalStreamClosedRemotely.connect(
   1556         mediastream_signaling_,
   1557         &MediaStreamSignaling::OnRemoteSctpDataChannelClosed);
   1558   }
   1559   return true;
   1560 }
   1561 
   1562 void WebRtcSession::CopySavedCandidates(
   1563     SessionDescriptionInterface* dest_desc) {
   1564   if (!dest_desc) {
   1565     ASSERT(false);
   1566     return;
   1567   }
   1568   for (size_t i = 0; i < saved_candidates_.size(); ++i) {
   1569     dest_desc->AddCandidate(saved_candidates_[i]);
   1570     delete saved_candidates_[i];
   1571   }
   1572   saved_candidates_.clear();
   1573 }
   1574 
   1575 void WebRtcSession::OnDataChannelMessageReceived(
   1576     cricket::DataChannel* channel,
   1577     const cricket::ReceiveDataParams& params,
   1578     const rtc::Buffer& payload) {
   1579   ASSERT(data_channel_type_ == cricket::DCT_SCTP);
   1580   if (params.type == cricket::DMT_CONTROL &&
   1581       mediastream_signaling_->IsSctpSidAvailable(params.ssrc)) {
   1582     // Received CONTROL on unused sid, process as an OPEN message.
   1583     mediastream_signaling_->AddDataChannelFromOpenMessage(params, payload);
   1584   }
   1585   // otherwise ignore the message.
   1586 }
   1587 
   1588 // Returns false if bundle is enabled and rtcp_mux is disabled.
   1589 bool WebRtcSession::ValidateBundleSettings(const SessionDescription* desc) {
   1590   bool bundle_enabled = desc->HasGroup(cricket::GROUP_TYPE_BUNDLE);
   1591   if (!bundle_enabled)
   1592     return true;
   1593 
   1594   const cricket::ContentGroup* bundle_group =
   1595       desc->GetGroupByName(cricket::GROUP_TYPE_BUNDLE);
   1596   ASSERT(bundle_group != NULL);
   1597 
   1598   const cricket::ContentInfos& contents = desc->contents();
   1599   for (cricket::ContentInfos::const_iterator citer = contents.begin();
   1600        citer != contents.end(); ++citer) {
   1601     const cricket::ContentInfo* content = (&*citer);
   1602     ASSERT(content != NULL);
   1603     if (bundle_group->HasContentName(content->name) &&
   1604         !content->rejected && content->type == cricket::NS_JINGLE_RTP) {
   1605       if (!HasRtcpMuxEnabled(content))
   1606         return false;
   1607     }
   1608   }
   1609   // RTCP-MUX is enabled in all the contents.
   1610   return true;
   1611 }
   1612 
   1613 bool WebRtcSession::HasRtcpMuxEnabled(
   1614     const cricket::ContentInfo* content) {
   1615   const cricket::MediaContentDescription* description =
   1616       static_cast<cricket::MediaContentDescription*>(content->description);
   1617   return description->rtcp_mux();
   1618 }
   1619 
   1620 bool WebRtcSession::ValidateSessionDescription(
   1621     const SessionDescriptionInterface* sdesc,
   1622     cricket::ContentSource source, std::string* err_desc) {
   1623   std::string type;
   1624   if (error() != cricket::BaseSession::ERROR_NONE) {
   1625     return BadSdp(source, type, GetSessionErrorMsg(), err_desc);
   1626   }
   1627 
   1628   if (!sdesc || !sdesc->description()) {
   1629     return BadSdp(source, type, kInvalidSdp, err_desc);
   1630   }
   1631 
   1632   type = sdesc->type();
   1633   Action action = GetAction(sdesc->type());
   1634   if (source == cricket::CS_LOCAL) {
   1635     if (!ExpectSetLocalDescription(action))
   1636       return BadLocalSdp(type, BadStateErrMsg(state()), err_desc);
   1637   } else {
   1638     if (!ExpectSetRemoteDescription(action))
   1639       return BadRemoteSdp(type, BadStateErrMsg(state()), err_desc);
   1640   }
   1641 
   1642   // Verify crypto settings.
   1643   std::string crypto_error;
   1644   if ((webrtc_session_desc_factory_->SdesPolicy() == cricket::SEC_REQUIRED ||
   1645        dtls_enabled_) &&
   1646       !VerifyCrypto(sdesc->description(), dtls_enabled_, &crypto_error)) {
   1647     return BadSdp(source, type, crypto_error, err_desc);
   1648   }
   1649 
   1650   // Verify ice-ufrag and ice-pwd.
   1651   if (!VerifyIceUfragPwdPresent(sdesc->description())) {
   1652     return BadSdp(source, type, kSdpWithoutIceUfragPwd, err_desc);
   1653   }
   1654 
   1655   if (!ValidateBundleSettings(sdesc->description())) {
   1656     return BadSdp(source, type, kBundleWithoutRtcpMux, err_desc);
   1657   }
   1658 
   1659   // Verify m-lines in Answer when compared against Offer.
   1660   if (action == kAnswer) {
   1661     const cricket::SessionDescription* offer_desc =
   1662         (source == cricket::CS_LOCAL) ? remote_description()->description() :
   1663             local_description()->description();
   1664     if (!VerifyMediaDescriptions(sdesc->description(), offer_desc)) {
   1665       return BadAnswerSdp(source, kMlineMismatch, err_desc);
   1666     }
   1667   }
   1668 
   1669   return true;
   1670 }
   1671 
   1672 bool WebRtcSession::ExpectSetLocalDescription(Action action) {
   1673   return ((action == kOffer && state() == STATE_INIT) ||
   1674           // update local offer
   1675           (action == kOffer && state() == STATE_SENTINITIATE) ||
   1676           // update the current ongoing session.
   1677           (action == kOffer && state() == STATE_RECEIVEDACCEPT) ||
   1678           (action == kOffer && state() == STATE_SENTACCEPT) ||
   1679           (action == kOffer && state() == STATE_INPROGRESS) ||
   1680           // accept remote offer
   1681           (action == kAnswer && state() == STATE_RECEIVEDINITIATE) ||
   1682           (action == kAnswer && state() == STATE_SENTPRACCEPT) ||
   1683           (action == kPrAnswer && state() == STATE_RECEIVEDINITIATE) ||
   1684           (action == kPrAnswer && state() == STATE_SENTPRACCEPT));
   1685 }
   1686 
   1687 bool WebRtcSession::ExpectSetRemoteDescription(Action action) {
   1688   return ((action == kOffer && state() == STATE_INIT) ||
   1689           // update remote offer
   1690           (action == kOffer && state() == STATE_RECEIVEDINITIATE) ||
   1691           // update the current ongoing session
   1692           (action == kOffer && state() == STATE_RECEIVEDACCEPT) ||
   1693           (action == kOffer && state() == STATE_SENTACCEPT) ||
   1694           (action == kOffer && state() == STATE_INPROGRESS) ||
   1695           // accept local offer
   1696           (action == kAnswer && state() == STATE_SENTINITIATE) ||
   1697           (action == kAnswer && state() == STATE_RECEIVEDPRACCEPT) ||
   1698           (action == kPrAnswer && state() == STATE_SENTINITIATE) ||
   1699           (action == kPrAnswer && state() == STATE_RECEIVEDPRACCEPT));
   1700 }
   1701 
   1702 std::string WebRtcSession::GetSessionErrorMsg() {
   1703   std::ostringstream desc;
   1704   desc << kSessionError << GetErrorCodeString(error()) << ". ";
   1705   desc << kSessionErrorDesc << error_desc() << ".";
   1706   return desc.str();
   1707 }
   1708 
   1709 // We need to check the local/remote description for the Transport instead of
   1710 // the session, because a new Transport added during renegotiation may have
   1711 // them unset while the session has them set from the previous negotiation.
   1712 // Not doing so may trigger the auto generation of transport description and
   1713 // mess up DTLS identity information, ICE credential, etc.
   1714 bool WebRtcSession::ReadyToUseRemoteCandidate(
   1715     const IceCandidateInterface* candidate,
   1716     const SessionDescriptionInterface* remote_desc,
   1717     bool* valid) {
   1718   *valid = true;;
   1719   cricket::TransportProxy* transport_proxy = NULL;
   1720 
   1721   const SessionDescriptionInterface* current_remote_desc =
   1722       remote_desc ? remote_desc : remote_description();
   1723 
   1724   if (!current_remote_desc)
   1725     return false;
   1726 
   1727   size_t mediacontent_index =
   1728       static_cast<size_t>(candidate->sdp_mline_index());
   1729   size_t remote_content_size =
   1730       current_remote_desc->description()->contents().size();
   1731   if (mediacontent_index >= remote_content_size) {
   1732     LOG(LS_ERROR)
   1733         << "ReadyToUseRemoteCandidate: Invalid candidate media index.";
   1734 
   1735     *valid = false;
   1736     return false;
   1737   }
   1738 
   1739   cricket::ContentInfo content =
   1740       current_remote_desc->description()->contents()[mediacontent_index];
   1741   transport_proxy = GetTransportProxy(content.name);
   1742 
   1743   return transport_proxy && transport_proxy->local_description_set() &&
   1744       transport_proxy->remote_description_set();
   1745 }
   1746 
   1747 }  // namespace webrtc
   1748