/* * Copyright 2004 The WebRTC project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #include "pc/media_session.h" #include #include #include #include #include #include #include #include "absl/algorithm/container.h" #include "absl/strings/match.h" #include "absl/types/optional.h" #include "api/crypto_params.h" #include "media/base/h264_profile_level_id.h" #include "media/base/media_constants.h" #include "media/sctp/sctp_transport_internal.h" #include "p2p/base/p2p_constants.h" #include "pc/channel_manager.h" #include "pc/media_protocol_names.h" #include "pc/rtp_media_utils.h" #include "pc/srtp_filter.h" #include "pc/used_ids.h" #include "rtc_base/checks.h" #include "rtc_base/helpers.h" #include "rtc_base/logging.h" #include "rtc_base/third_party/base64/base64.h" #include "rtc_base/unique_id_generator.h" namespace { using rtc::UniqueRandomIdGenerator; using webrtc::RtpTransceiverDirection; const char kInline[] = "inline:"; void GetSupportedSdesCryptoSuiteNames( void (*func)(const webrtc::CryptoOptions&, std::vector*), const webrtc::CryptoOptions& crypto_options, std::vector* names) { std::vector crypto_suites; func(crypto_options, &crypto_suites); for (const auto crypto : crypto_suites) { names->push_back(rtc::SrtpCryptoSuiteToName(crypto)); } } webrtc::RtpExtension RtpExtensionFromCapability( const webrtc::RtpHeaderExtensionCapability& capability) { return webrtc::RtpExtension(capability.uri, capability.preferred_id.value_or(1)); } cricket::RtpHeaderExtensions RtpHeaderExtensionsFromCapabilities( const std::vector& capabilities) { cricket::RtpHeaderExtensions exts; for (const auto& capability : capabilities) { exts.push_back(RtpExtensionFromCapability(capability)); } return exts; } std::vector UnstoppedRtpHeaderExtensionCapabilities( std::vector capabilities) { capabilities.erase( std::remove_if( capabilities.begin(), capabilities.end(), [](const webrtc::RtpHeaderExtensionCapability& capability) { return capability.direction == RtpTransceiverDirection::kStopped; }), capabilities.end()); return capabilities; } bool IsCapabilityPresent(const webrtc::RtpHeaderExtensionCapability& capability, const cricket::RtpHeaderExtensions& extensions) { return std::find_if(extensions.begin(), extensions.end(), [&capability](const webrtc::RtpExtension& extension) { return capability.uri == extension.uri; }) != extensions.end(); } cricket::RtpHeaderExtensions UnstoppedOrPresentRtpHeaderExtensions( const std::vector& capabilities, const cricket::RtpHeaderExtensions& unencrypted, const cricket::RtpHeaderExtensions& encrypted) { cricket::RtpHeaderExtensions extensions; for (const auto& capability : capabilities) { if (capability.direction != RtpTransceiverDirection::kStopped || IsCapabilityPresent(capability, unencrypted) || IsCapabilityPresent(capability, encrypted)) { extensions.push_back(RtpExtensionFromCapability(capability)); } } return extensions; } } // namespace namespace cricket { // RTP Profile names // http://www.iana.org/assignments/rtp-parameters/rtp-parameters.xml // RFC4585 const char kMediaProtocolAvpf[] = "RTP/AVPF"; // RFC5124 const char kMediaProtocolDtlsSavpf[] = "UDP/TLS/RTP/SAVPF"; // We always generate offers with "UDP/TLS/RTP/SAVPF" when using DTLS-SRTP, // but we tolerate "RTP/SAVPF" in offers we receive, for compatibility. const char kMediaProtocolSavpf[] = "RTP/SAVPF"; // Note that the below functions support some protocol strings purely for // legacy compatibility, as required by JSEP in Section 5.1.2, Profile Names // and Interoperability. static bool IsDtlsRtp(const std::string& protocol) { // Most-likely values first. return protocol == "UDP/TLS/RTP/SAVPF" || protocol == "TCP/TLS/RTP/SAVPF" || protocol == "UDP/TLS/RTP/SAVP" || protocol == "TCP/TLS/RTP/SAVP"; } static bool IsPlainRtp(const std::string& protocol) { // Most-likely values first. return protocol == "RTP/SAVPF" || protocol == "RTP/AVPF" || protocol == "RTP/SAVP" || protocol == "RTP/AVP"; } static RtpTransceiverDirection NegotiateRtpTransceiverDirection( RtpTransceiverDirection offer, RtpTransceiverDirection wants) { bool offer_send = webrtc::RtpTransceiverDirectionHasSend(offer); bool offer_recv = webrtc::RtpTransceiverDirectionHasRecv(offer); bool wants_send = webrtc::RtpTransceiverDirectionHasSend(wants); bool wants_recv = webrtc::RtpTransceiverDirectionHasRecv(wants); return webrtc::RtpTransceiverDirectionFromSendRecv(offer_recv && wants_send, offer_send && wants_recv); } static bool IsMediaContentOfType(const ContentInfo* content, MediaType media_type) { if (!content || !content->media_description()) { return false; } return content->media_description()->type() == media_type; } static bool CreateCryptoParams(int tag, const std::string& cipher, CryptoParams* crypto_out) { int key_len; int salt_len; if (!rtc::GetSrtpKeyAndSaltLengths(rtc::SrtpCryptoSuiteFromName(cipher), &key_len, &salt_len)) { return false; } int master_key_len = key_len + salt_len; std::string master_key; if (!rtc::CreateRandomData(master_key_len, &master_key)) { return false; } RTC_CHECK_EQ(master_key_len, master_key.size()); std::string key = rtc::Base64::Encode(master_key); crypto_out->tag = tag; crypto_out->cipher_suite = cipher; crypto_out->key_params = kInline; crypto_out->key_params += key; return true; } static bool AddCryptoParams(const std::string& cipher_suite, CryptoParamsVec* cryptos_out) { int size = static_cast(cryptos_out->size()); cryptos_out->resize(size + 1); return CreateCryptoParams(size, cipher_suite, &cryptos_out->at(size)); } void AddMediaCryptos(const CryptoParamsVec& cryptos, MediaContentDescription* media) { for (const CryptoParams& crypto : cryptos) { media->AddCrypto(crypto); } } bool CreateMediaCryptos(const std::vector& crypto_suites, MediaContentDescription* media) { CryptoParamsVec cryptos; for (const std::string& crypto_suite : crypto_suites) { if (!AddCryptoParams(crypto_suite, &cryptos)) { return false; } } AddMediaCryptos(cryptos, media); return true; } const CryptoParamsVec* GetCryptos(const ContentInfo* content) { if (!content || !content->media_description()) { return nullptr; } return &content->media_description()->cryptos(); } bool FindMatchingCrypto(const CryptoParamsVec& cryptos, const CryptoParams& crypto, CryptoParams* crypto_out) { auto it = absl::c_find_if( cryptos, [&crypto](const CryptoParams& c) { return crypto.Matches(c); }); if (it == cryptos.end()) { return false; } *crypto_out = *it; return true; } // For audio, HMAC 32 (if enabled) is prefered over HMAC 80 because of the // low overhead. void GetSupportedAudioSdesCryptoSuites( const webrtc::CryptoOptions& crypto_options, std::vector* crypto_suites) { if (crypto_options.srtp.enable_aes128_sha1_32_crypto_cipher) { crypto_suites->push_back(rtc::SRTP_AES128_CM_SHA1_32); } crypto_suites->push_back(rtc::SRTP_AES128_CM_SHA1_80); if (crypto_options.srtp.enable_gcm_crypto_suites) { crypto_suites->push_back(rtc::SRTP_AEAD_AES_256_GCM); crypto_suites->push_back(rtc::SRTP_AEAD_AES_128_GCM); } } void GetSupportedAudioSdesCryptoSuiteNames( const webrtc::CryptoOptions& crypto_options, std::vector* crypto_suite_names) { GetSupportedSdesCryptoSuiteNames(GetSupportedAudioSdesCryptoSuites, crypto_options, crypto_suite_names); } void GetSupportedVideoSdesCryptoSuites( const webrtc::CryptoOptions& crypto_options, std::vector* crypto_suites) { crypto_suites->push_back(rtc::SRTP_AES128_CM_SHA1_80); if (crypto_options.srtp.enable_gcm_crypto_suites) { crypto_suites->push_back(rtc::SRTP_AEAD_AES_256_GCM); crypto_suites->push_back(rtc::SRTP_AEAD_AES_128_GCM); } } void GetSupportedVideoSdesCryptoSuiteNames( const webrtc::CryptoOptions& crypto_options, std::vector* crypto_suite_names) { GetSupportedSdesCryptoSuiteNames(GetSupportedVideoSdesCryptoSuites, crypto_options, crypto_suite_names); } void GetSupportedDataSdesCryptoSuites( const webrtc::CryptoOptions& crypto_options, std::vector* crypto_suites) { crypto_suites->push_back(rtc::SRTP_AES128_CM_SHA1_80); if (crypto_options.srtp.enable_gcm_crypto_suites) { crypto_suites->push_back(rtc::SRTP_AEAD_AES_256_GCM); crypto_suites->push_back(rtc::SRTP_AEAD_AES_128_GCM); } } void GetSupportedDataSdesCryptoSuiteNames( const webrtc::CryptoOptions& crypto_options, std::vector* crypto_suite_names) { GetSupportedSdesCryptoSuiteNames(GetSupportedDataSdesCryptoSuites, crypto_options, crypto_suite_names); } // Support any GCM cipher (if enabled through options). For video support only // 80-bit SHA1 HMAC. For audio 32-bit HMAC is tolerated (if enabled) unless // bundle is enabled because it is low overhead. // Pick the crypto in the list that is supported. static bool SelectCrypto(const MediaContentDescription* offer, bool bundle, const webrtc::CryptoOptions& crypto_options, CryptoParams* crypto_out) { bool audio = offer->type() == MEDIA_TYPE_AUDIO; const CryptoParamsVec& cryptos = offer->cryptos(); for (const CryptoParams& crypto : cryptos) { if ((crypto_options.srtp.enable_gcm_crypto_suites && rtc::IsGcmCryptoSuiteName(crypto.cipher_suite)) || rtc::CS_AES_CM_128_HMAC_SHA1_80 == crypto.cipher_suite || (rtc::CS_AES_CM_128_HMAC_SHA1_32 == crypto.cipher_suite && audio && !bundle && crypto_options.srtp.enable_aes128_sha1_32_crypto_cipher)) { return CreateCryptoParams(crypto.tag, crypto.cipher_suite, crypto_out); } } return false; } // Finds all StreamParams of all media types and attach them to stream_params. static StreamParamsVec GetCurrentStreamParams( const std::vector& active_local_contents) { StreamParamsVec stream_params; for (const ContentInfo* content : active_local_contents) { for (const StreamParams& params : content->media_description()->streams()) { stream_params.push_back(params); } } return stream_params; } static StreamParams CreateStreamParamsForNewSenderWithSsrcs( const SenderOptions& sender, const std::string& rtcp_cname, bool include_rtx_streams, bool include_flexfec_stream, UniqueRandomIdGenerator* ssrc_generator) { StreamParams result; result.id = sender.track_id; // TODO(brandtr): Update when we support multistream protection. if (include_flexfec_stream && sender.num_sim_layers > 1) { include_flexfec_stream = false; RTC_LOG(LS_WARNING) << "Our FlexFEC implementation only supports protecting " "a single media streams. This session has multiple " "media streams however, so no FlexFEC SSRC will be generated."; } result.GenerateSsrcs(sender.num_sim_layers, include_rtx_streams, include_flexfec_stream, ssrc_generator); result.cname = rtcp_cname; result.set_stream_ids(sender.stream_ids); return result; } static bool ValidateSimulcastLayers( const std::vector& rids, const SimulcastLayerList& simulcast_layers) { return absl::c_all_of( simulcast_layers.GetAllLayers(), [&rids](const SimulcastLayer& layer) { return absl::c_any_of(rids, [&layer](const RidDescription& rid) { return rid.rid == layer.rid; }); }); } static StreamParams CreateStreamParamsForNewSenderWithRids( const SenderOptions& sender, const std::string& rtcp_cname) { RTC_DCHECK(!sender.rids.empty()); RTC_DCHECK_EQ(sender.num_sim_layers, 0) << "RIDs are the compliant way to indicate simulcast."; RTC_DCHECK(ValidateSimulcastLayers(sender.rids, sender.simulcast_layers)); StreamParams result; result.id = sender.track_id; result.cname = rtcp_cname; result.set_stream_ids(sender.stream_ids); // More than one rid should be signaled. if (sender.rids.size() > 1) { result.set_rids(sender.rids); } return result; } // Adds SimulcastDescription if indicated by the media description options. // MediaContentDescription should already be set up with the send rids. static void AddSimulcastToMediaDescription( const MediaDescriptionOptions& media_description_options, MediaContentDescription* description) { RTC_DCHECK(description); // Check if we are using RIDs in this scenario. if (absl::c_all_of(description->streams(), [](const StreamParams& params) { return !params.has_rids(); })) { return; } RTC_DCHECK_EQ(1, description->streams().size()) << "RIDs are only supported in Unified Plan semantics."; RTC_DCHECK_EQ(1, media_description_options.sender_options.size()); RTC_DCHECK(description->type() == MediaType::MEDIA_TYPE_AUDIO || description->type() == MediaType::MEDIA_TYPE_VIDEO); // One RID or less indicates that simulcast is not needed. if (description->streams()[0].rids().size() <= 1) { return; } // Only negotiate the send layers. SimulcastDescription simulcast; simulcast.send_layers() = media_description_options.sender_options[0].simulcast_layers; description->set_simulcast_description(simulcast); } // Adds a StreamParams for each SenderOptions in |sender_options| to // content_description. // |current_params| - All currently known StreamParams of any media type. template static bool AddStreamParams( const std::vector& sender_options, const std::string& rtcp_cname, UniqueRandomIdGenerator* ssrc_generator, StreamParamsVec* current_streams, MediaContentDescriptionImpl* content_description) { // SCTP streams are not negotiated using SDP/ContentDescriptions. if (IsSctpProtocol(content_description->protocol())) { return true; } const bool include_rtx_streams = ContainsRtxCodec(content_description->codecs()); const bool include_flexfec_stream = ContainsFlexfecCodec(content_description->codecs()); for (const SenderOptions& sender : sender_options) { // groupid is empty for StreamParams generated using // MediaSessionDescriptionFactory. StreamParams* param = GetStreamByIds(*current_streams, "" /*group_id*/, sender.track_id); if (!param) { // This is a new sender. StreamParams stream_param = sender.rids.empty() ? // Signal SSRCs and legacy simulcast (if requested). CreateStreamParamsForNewSenderWithSsrcs( sender, rtcp_cname, include_rtx_streams, include_flexfec_stream, ssrc_generator) : // Signal RIDs and spec-compliant simulcast (if requested). CreateStreamParamsForNewSenderWithRids(sender, rtcp_cname); content_description->AddStream(stream_param); // Store the new StreamParams in current_streams. // This is necessary so that we can use the CNAME for other media types. current_streams->push_back(stream_param); } else { // Use existing generated SSRCs/groups, but update the sync_label if // necessary. This may be needed if a MediaStreamTrack was moved from one // MediaStream to another. param->set_stream_ids(sender.stream_ids); content_description->AddStream(*param); } } return true; } // Updates the transport infos of the |sdesc| according to the given // |bundle_group|. The transport infos of the content names within the // |bundle_group| should be updated to use the ufrag, pwd and DTLS role of the // first content within the |bundle_group|. static bool UpdateTransportInfoForBundle(const ContentGroup& bundle_group, SessionDescription* sdesc) { // The bundle should not be empty. if (!sdesc || !bundle_group.FirstContentName()) { return false; } // We should definitely have a transport for the first content. const std::string& selected_content_name = *bundle_group.FirstContentName(); const TransportInfo* selected_transport_info = sdesc->GetTransportInfoByName(selected_content_name); if (!selected_transport_info) { return false; } // Set the other contents to use the same ICE credentials. const std::string& selected_ufrag = selected_transport_info->description.ice_ufrag; const std::string& selected_pwd = selected_transport_info->description.ice_pwd; ConnectionRole selected_connection_role = selected_transport_info->description.connection_role; for (TransportInfo& transport_info : sdesc->transport_infos()) { if (bundle_group.HasContentName(transport_info.content_name) && transport_info.content_name != selected_content_name) { transport_info.description.ice_ufrag = selected_ufrag; transport_info.description.ice_pwd = selected_pwd; transport_info.description.connection_role = selected_connection_role; } } return true; } // Gets the CryptoParamsVec of the given |content_name| from |sdesc|, and // sets it to |cryptos|. static bool GetCryptosByName(const SessionDescription* sdesc, const std::string& content_name, CryptoParamsVec* cryptos) { if (!sdesc || !cryptos) { return false; } const ContentInfo* content = sdesc->GetContentByName(content_name); if (!content || !content->media_description()) { return false; } *cryptos = content->media_description()->cryptos(); return true; } // Prunes the |target_cryptos| by removing the crypto params (cipher_suite) // which are not available in |filter|. static void PruneCryptos(const CryptoParamsVec& filter, CryptoParamsVec* target_cryptos) { if (!target_cryptos) { return; } target_cryptos->erase( std::remove_if(target_cryptos->begin(), target_cryptos->end(), // Returns true if the |crypto|'s cipher_suite is not // found in |filter|. [&filter](const CryptoParams& crypto) { for (const CryptoParams& entry : filter) { if (entry.cipher_suite == crypto.cipher_suite) return false; } return true; }), target_cryptos->end()); } static bool IsRtpContent(SessionDescription* sdesc, const std::string& content_name) { bool is_rtp = false; ContentInfo* content = sdesc->GetContentByName(content_name); if (content && content->media_description()) { is_rtp = IsRtpProtocol(content->media_description()->protocol()); } return is_rtp; } // Updates the crypto parameters of the |sdesc| according to the given // |bundle_group|. The crypto parameters of all the contents within the // |bundle_group| should be updated to use the common subset of the // available cryptos. static bool UpdateCryptoParamsForBundle(const ContentGroup& bundle_group, SessionDescription* sdesc) { // The bundle should not be empty. if (!sdesc || !bundle_group.FirstContentName()) { return false; } bool common_cryptos_needed = false; // Get the common cryptos. const ContentNames& content_names = bundle_group.content_names(); CryptoParamsVec common_cryptos; bool first = true; for (const std::string& content_name : content_names) { if (!IsRtpContent(sdesc, content_name)) { continue; } // The common cryptos are needed if any of the content does not have DTLS // enabled. if (!sdesc->GetTransportInfoByName(content_name)->description.secure()) { common_cryptos_needed = true; } if (first) { first = false; // Initial the common_cryptos with the first content in the bundle group. if (!GetCryptosByName(sdesc, content_name, &common_cryptos)) { return false; } if (common_cryptos.empty()) { // If there's no crypto params, we should just return. return true; } } else { CryptoParamsVec cryptos; if (!GetCryptosByName(sdesc, content_name, &cryptos)) { return false; } PruneCryptos(cryptos, &common_cryptos); } } if (common_cryptos.empty() && common_cryptos_needed) { return false; } // Update to use the common cryptos. for (const std::string& content_name : content_names) { if (!IsRtpContent(sdesc, content_name)) { continue; } ContentInfo* content = sdesc->GetContentByName(content_name); if (IsMediaContent(content)) { MediaContentDescription* media_desc = content->media_description(); if (!media_desc) { return false; } media_desc->set_cryptos(common_cryptos); } } return true; } static std::vector GetActiveContents( const SessionDescription& description, const MediaSessionOptions& session_options) { std::vector active_contents; for (size_t i = 0; i < description.contents().size(); ++i) { RTC_DCHECK_LT(i, session_options.media_description_options.size()); const ContentInfo& content = description.contents()[i]; const MediaDescriptionOptions& media_options = session_options.media_description_options[i]; if (!content.rejected && !media_options.stopped && content.name == media_options.mid) { active_contents.push_back(&content); } } return active_contents; } template static bool ContainsRtxCodec(const std::vector& codecs) { for (const auto& codec : codecs) { if (IsRtxCodec(codec)) { return true; } } return false; } template static bool IsRtxCodec(const C& codec) { return absl::EqualsIgnoreCase(codec.name, kRtxCodecName); } template static bool ContainsFlexfecCodec(const std::vector& codecs) { for (const auto& codec : codecs) { if (IsFlexfecCodec(codec)) { return true; } } return false; } template static bool IsFlexfecCodec(const C& codec) { return absl::EqualsIgnoreCase(codec.name, kFlexfecCodecName); } // Create a media content to be offered for the given |sender_options|, // according to the given options.rtcp_mux, session_options.is_muc, codecs, // secure_transport, crypto, and current_streams. If we don't currently have // crypto (in current_cryptos) and it is enabled (in secure_policy), crypto is // created (according to crypto_suites). The created content is added to the // offer. static bool CreateContentOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const SecurePolicy& secure_policy, const CryptoParamsVec* current_cryptos, const std::vector& crypto_suites, const RtpHeaderExtensions& rtp_extensions, UniqueRandomIdGenerator* ssrc_generator, StreamParamsVec* current_streams, MediaContentDescription* offer) { offer->set_rtcp_mux(session_options.rtcp_mux_enabled); if (offer->type() == cricket::MEDIA_TYPE_VIDEO) { offer->set_rtcp_reduced_size(true); } // Build the vector of header extensions with directions for this // media_description's options. RtpHeaderExtensions extensions; for (auto extension_with_id : rtp_extensions) { for (const auto& extension : media_description_options.header_extensions) { if (extension_with_id.uri == extension.uri) { // TODO(crbug.com/1051821): Configure the extension direction from // the information in the media_description_options extension // capability. extensions.push_back(extension_with_id); } } } offer->set_rtp_header_extensions(extensions); AddSimulcastToMediaDescription(media_description_options, offer); if (secure_policy != SEC_DISABLED) { if (current_cryptos) { AddMediaCryptos(*current_cryptos, offer); } if (offer->cryptos().empty()) { if (!CreateMediaCryptos(crypto_suites, offer)) { return false; } } } if (secure_policy == SEC_REQUIRED && offer->cryptos().empty()) { return false; } return true; } template static bool CreateMediaContentOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const std::vector& codecs, const SecurePolicy& secure_policy, const CryptoParamsVec* current_cryptos, const std::vector& crypto_suites, const RtpHeaderExtensions& rtp_extensions, UniqueRandomIdGenerator* ssrc_generator, StreamParamsVec* current_streams, MediaContentDescriptionImpl* offer) { offer->AddCodecs(codecs); if (!AddStreamParams(media_description_options.sender_options, session_options.rtcp_cname, ssrc_generator, current_streams, offer)) { return false; } return CreateContentOffer(media_description_options, session_options, secure_policy, current_cryptos, crypto_suites, rtp_extensions, ssrc_generator, current_streams, offer); } template static bool ReferencedCodecsMatch(const std::vector& codecs1, const int codec1_id, const std::vector& codecs2, const int codec2_id) { const C* codec1 = FindCodecById(codecs1, codec1_id); const C* codec2 = FindCodecById(codecs2, codec2_id); return codec1 != nullptr && codec2 != nullptr && codec1->Matches(*codec2); } template static void NegotiatePacketization(const C& local_codec, const C& remote_codec, C* negotiated_codec) {} template <> void NegotiatePacketization(const VideoCodec& local_codec, const VideoCodec& remote_codec, VideoCodec* negotiated_codec) { negotiated_codec->packetization = VideoCodec::IntersectPacketization(local_codec, remote_codec); } template static void NegotiateCodecs(const std::vector& local_codecs, const std::vector& offered_codecs, std::vector* negotiated_codecs, bool keep_offer_order) { for (const C& ours : local_codecs) { C theirs; // Note that we intentionally only find one matching codec for each of our // local codecs, in case the remote offer contains duplicate codecs. if (FindMatchingCodec(local_codecs, offered_codecs, ours, &theirs)) { C negotiated = ours; NegotiatePacketization(ours, theirs, &negotiated); negotiated.IntersectFeedbackParams(theirs); if (IsRtxCodec(negotiated)) { const auto apt_it = theirs.params.find(kCodecParamAssociatedPayloadType); // FindMatchingCodec shouldn't return something with no apt value. RTC_DCHECK(apt_it != theirs.params.end()); negotiated.SetParam(kCodecParamAssociatedPayloadType, apt_it->second); } if (absl::EqualsIgnoreCase(ours.name, kH264CodecName)) { webrtc::H264::GenerateProfileLevelIdForAnswer( ours.params, theirs.params, &negotiated.params); } negotiated.id = theirs.id; negotiated.name = theirs.name; negotiated_codecs->push_back(std::move(negotiated)); } } if (keep_offer_order) { // RFC3264: Although the answerer MAY list the formats in their desired // order of preference, it is RECOMMENDED that unless there is a // specific reason, the answerer list formats in the same relative order // they were present in the offer. // This can be skipped when the transceiver has any codec preferences. std::unordered_map payload_type_preferences; int preference = static_cast(offered_codecs.size() + 1); for (const C& codec : offered_codecs) { payload_type_preferences[codec.id] = preference--; } absl::c_sort(*negotiated_codecs, [&payload_type_preferences](const C& a, const C& b) { return payload_type_preferences[a.id] > payload_type_preferences[b.id]; }); } } // Finds a codec in |codecs2| that matches |codec_to_match|, which is // a member of |codecs1|. If |codec_to_match| is an RTX codec, both // the codecs themselves and their associated codecs must match. template static bool FindMatchingCodec(const std::vector& codecs1, const std::vector& codecs2, const C& codec_to_match, C* found_codec) { // |codec_to_match| should be a member of |codecs1|, in order to look up RTX // codecs' associated codecs correctly. If not, that's a programming error. RTC_DCHECK(absl::c_any_of(codecs1, [&codec_to_match](const C& codec) { return &codec == &codec_to_match; })); for (const C& potential_match : codecs2) { if (potential_match.Matches(codec_to_match)) { if (IsRtxCodec(codec_to_match)) { int apt_value_1 = 0; int apt_value_2 = 0; if (!codec_to_match.GetParam(kCodecParamAssociatedPayloadType, &apt_value_1) || !potential_match.GetParam(kCodecParamAssociatedPayloadType, &apt_value_2)) { RTC_LOG(LS_WARNING) << "RTX missing associated payload type."; continue; } if (!ReferencedCodecsMatch(codecs1, apt_value_1, codecs2, apt_value_2)) { continue; } } if (found_codec) { *found_codec = potential_match; } return true; } } return false; } // Find the codec in |codec_list| that |rtx_codec| is associated with. template static const C* GetAssociatedCodec(const std::vector& codec_list, const C& rtx_codec) { std::string associated_pt_str; if (!rtx_codec.GetParam(kCodecParamAssociatedPayloadType, &associated_pt_str)) { RTC_LOG(LS_WARNING) << "RTX codec " << rtx_codec.name << " is missing an associated payload type."; return nullptr; } int associated_pt; if (!rtc::FromString(associated_pt_str, &associated_pt)) { RTC_LOG(LS_WARNING) << "Couldn't convert payload type " << associated_pt_str << " of RTX codec " << rtx_codec.name << " to an integer."; return nullptr; } // Find the associated reference codec for the reference RTX codec. const C* associated_codec = FindCodecById(codec_list, associated_pt); if (!associated_codec) { RTC_LOG(LS_WARNING) << "Couldn't find associated codec with payload type " << associated_pt << " for RTX codec " << rtx_codec.name << "."; } return associated_codec; } // Adds all codecs from |reference_codecs| to |offered_codecs| that don't // already exist in |offered_codecs| and ensure the payload types don't // collide. template static void MergeCodecs(const std::vector& reference_codecs, std::vector* offered_codecs, UsedPayloadTypes* used_pltypes) { // Add all new codecs that are not RTX codecs. for (const C& reference_codec : reference_codecs) { if (!IsRtxCodec(reference_codec) && !FindMatchingCodec(reference_codecs, *offered_codecs, reference_codec, nullptr)) { C codec = reference_codec; used_pltypes->FindAndSetIdUsed(&codec); offered_codecs->push_back(codec); } } // Add all new RTX codecs. for (const C& reference_codec : reference_codecs) { if (IsRtxCodec(reference_codec) && !FindMatchingCodec(reference_codecs, *offered_codecs, reference_codec, nullptr)) { C rtx_codec = reference_codec; const C* associated_codec = GetAssociatedCodec(reference_codecs, rtx_codec); if (!associated_codec) { continue; } // Find a codec in the offered list that matches the reference codec. // Its payload type may be different than the reference codec. C matching_codec; if (!FindMatchingCodec(reference_codecs, *offered_codecs, *associated_codec, &matching_codec)) { RTC_LOG(LS_WARNING) << "Couldn't find matching " << associated_codec->name << " codec."; continue; } rtx_codec.params[kCodecParamAssociatedPayloadType] = rtc::ToString(matching_codec.id); used_pltypes->FindAndSetIdUsed(&rtx_codec); offered_codecs->push_back(rtx_codec); } } } template static Codecs MatchCodecPreference( const std::vector& codec_preferences, const Codecs& codecs) { Codecs filtered_codecs; std::set kept_codecs_ids; bool want_rtx = false; for (const auto& codec_preference : codec_preferences) { auto found_codec = absl::c_find_if( codecs, [&codec_preference](const typename Codecs::value_type& codec) { webrtc::RtpCodecParameters codec_parameters = codec.ToCodecParameters(); return codec_parameters.name == codec_preference.name && codec_parameters.kind == codec_preference.kind && codec_parameters.num_channels == codec_preference.num_channels && codec_parameters.clock_rate == codec_preference.clock_rate && codec_parameters.parameters == codec_preference.parameters; }); if (found_codec != codecs.end()) { filtered_codecs.push_back(*found_codec); kept_codecs_ids.insert(std::to_string(found_codec->id)); } else if (IsRtxCodec(codec_preference)) { want_rtx = true; } } if (want_rtx) { for (const auto& codec : codecs) { if (IsRtxCodec(codec)) { const auto apt = codec.params.find(cricket::kCodecParamAssociatedPayloadType); if (apt != codec.params.end() && kept_codecs_ids.count(apt->second) > 0) { filtered_codecs.push_back(codec); } } } } return filtered_codecs; } static bool FindByUriAndEncryption(const RtpHeaderExtensions& extensions, const webrtc::RtpExtension& ext_to_match, webrtc::RtpExtension* found_extension) { auto it = absl::c_find_if( extensions, [&ext_to_match](const webrtc::RtpExtension& extension) { // We assume that all URIs are given in a canonical // format. return extension.uri == ext_to_match.uri && extension.encrypt == ext_to_match.encrypt; }); if (it == extensions.end()) { return false; } if (found_extension) { *found_extension = *it; } return true; } static bool FindByUri(const RtpHeaderExtensions& extensions, const webrtc::RtpExtension& ext_to_match, webrtc::RtpExtension* found_extension) { // We assume that all URIs are given in a canonical format. const webrtc::RtpExtension* found = webrtc::RtpExtension::FindHeaderExtensionByUri(extensions, ext_to_match.uri); if (!found) { return false; } if (found_extension) { *found_extension = *found; } return true; } static bool FindByUriWithEncryptionPreference( const RtpHeaderExtensions& extensions, absl::string_view uri_to_match, bool encryption_preference, webrtc::RtpExtension* found_extension) { const webrtc::RtpExtension* unencrypted_extension = nullptr; for (const webrtc::RtpExtension& extension : extensions) { // We assume that all URIs are given in a canonical format. if (extension.uri == uri_to_match) { if (!encryption_preference || extension.encrypt) { if (found_extension) { *found_extension = extension; } return true; } unencrypted_extension = &extension; } } if (unencrypted_extension) { if (found_extension) { *found_extension = *unencrypted_extension; } return true; } return false; } // Adds all extensions from |reference_extensions| to |offered_extensions| that // don't already exist in |offered_extensions| and ensure the IDs don't // collide. If an extension is added, it's also added to |regular_extensions| or // |encrypted_extensions|, and if the extension is in |regular_extensions| or // |encrypted_extensions|, its ID is marked as used in |used_ids|. // |offered_extensions| is for either audio or video while |regular_extensions| // and |encrypted_extensions| are used for both audio and video. There could be // overlap between audio extensions and video extensions. static void MergeRtpHdrExts(const RtpHeaderExtensions& reference_extensions, RtpHeaderExtensions* offered_extensions, RtpHeaderExtensions* regular_extensions, RtpHeaderExtensions* encrypted_extensions, UsedRtpHeaderExtensionIds* used_ids) { for (auto reference_extension : reference_extensions) { if (!FindByUriAndEncryption(*offered_extensions, reference_extension, nullptr)) { webrtc::RtpExtension existing; if (reference_extension.encrypt) { if (FindByUriAndEncryption(*encrypted_extensions, reference_extension, &existing)) { offered_extensions->push_back(existing); } else { used_ids->FindAndSetIdUsed(&reference_extension); encrypted_extensions->push_back(reference_extension); offered_extensions->push_back(reference_extension); } } else { if (FindByUriAndEncryption(*regular_extensions, reference_extension, &existing)) { offered_extensions->push_back(existing); } else { used_ids->FindAndSetIdUsed(&reference_extension); regular_extensions->push_back(reference_extension); offered_extensions->push_back(reference_extension); } } } } } static void AddEncryptedVersionsOfHdrExts(RtpHeaderExtensions* extensions, RtpHeaderExtensions* all_extensions, UsedRtpHeaderExtensionIds* used_ids) { RtpHeaderExtensions encrypted_extensions; for (const webrtc::RtpExtension& extension : *extensions) { webrtc::RtpExtension existing; // Don't add encrypted extensions again that were already included in a // previous offer or regular extensions that are also included as encrypted // extensions. if (extension.encrypt || !webrtc::RtpExtension::IsEncryptionSupported(extension.uri) || (FindByUriWithEncryptionPreference(*extensions, extension.uri, true, &existing) && existing.encrypt)) { continue; } if (FindByUri(*all_extensions, extension, &existing)) { encrypted_extensions.push_back(existing); } else { webrtc::RtpExtension encrypted(extension); encrypted.encrypt = true; used_ids->FindAndSetIdUsed(&encrypted); all_extensions->push_back(encrypted); encrypted_extensions.push_back(encrypted); } } extensions->insert(extensions->end(), encrypted_extensions.begin(), encrypted_extensions.end()); } static void NegotiateRtpHeaderExtensions( const RtpHeaderExtensions& local_extensions, const RtpHeaderExtensions& offered_extensions, bool enable_encrypted_rtp_header_extensions, RtpHeaderExtensions* negotiated_extensions) { // TransportSequenceNumberV2 is not offered by default. The special logic for // the TransportSequenceNumber extensions works as follows: // Offer Answer // V1 V1 if in local_extensions. // V1 and V2 V2 regardless of local_extensions. // V2 V2 regardless of local_extensions. const webrtc::RtpExtension* transport_sequence_number_v2_offer = webrtc::RtpExtension::FindHeaderExtensionByUri( offered_extensions, webrtc::RtpExtension::kTransportSequenceNumberV2Uri); bool frame_descriptor_in_local = false; bool dependency_descriptor_in_local = false; bool abs_capture_time_in_local = false; for (const webrtc::RtpExtension& ours : local_extensions) { if (ours.uri == webrtc::RtpExtension::kGenericFrameDescriptorUri00) frame_descriptor_in_local = true; else if (ours.uri == webrtc::RtpExtension::kDependencyDescriptorUri) dependency_descriptor_in_local = true; else if (ours.uri == webrtc::RtpExtension::kAbsoluteCaptureTimeUri) abs_capture_time_in_local = true; webrtc::RtpExtension theirs; if (FindByUriWithEncryptionPreference( offered_extensions, ours.uri, enable_encrypted_rtp_header_extensions, &theirs)) { if (transport_sequence_number_v2_offer && ours.uri == webrtc::RtpExtension::kTransportSequenceNumberUri) { // Don't respond to // http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01 // if we get an offer including // http://www.webrtc.org/experiments/rtp-hdrext/transport-wide-cc-02 continue; } else { // We respond with their RTP header extension id. negotiated_extensions->push_back(theirs); } } } if (transport_sequence_number_v2_offer) { // Respond that we support kTransportSequenceNumberV2Uri. negotiated_extensions->push_back(*transport_sequence_number_v2_offer); } // Frame descriptors support. If the extension is not present locally, but is // in the offer, we add it to the list. webrtc::RtpExtension theirs; if (!dependency_descriptor_in_local && FindByUriWithEncryptionPreference( offered_extensions, webrtc::RtpExtension::kDependencyDescriptorUri, enable_encrypted_rtp_header_extensions, &theirs)) { negotiated_extensions->push_back(theirs); } if (!frame_descriptor_in_local && FindByUriWithEncryptionPreference( offered_extensions, webrtc::RtpExtension::kGenericFrameDescriptorUri00, enable_encrypted_rtp_header_extensions, &theirs)) { negotiated_extensions->push_back(theirs); } // Absolute capture time support. If the extension is not present locally, but // is in the offer, we add it to the list. if (!abs_capture_time_in_local && FindByUriWithEncryptionPreference( offered_extensions, webrtc::RtpExtension::kAbsoluteCaptureTimeUri, enable_encrypted_rtp_header_extensions, &theirs)) { negotiated_extensions->push_back(theirs); } } static void StripCNCodecs(AudioCodecs* audio_codecs) { audio_codecs->erase(std::remove_if(audio_codecs->begin(), audio_codecs->end(), [](const AudioCodec& codec) { return absl::EqualsIgnoreCase( codec.name, kComfortNoiseCodecName); }), audio_codecs->end()); } template static bool SetCodecsInAnswer( const MediaContentDescriptionImpl* offer, const std::vector& local_codecs, const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, UniqueRandomIdGenerator* ssrc_generator, StreamParamsVec* current_streams, MediaContentDescriptionImpl* answer) { std::vector negotiated_codecs; NegotiateCodecs(local_codecs, offer->codecs(), &negotiated_codecs, media_description_options.codec_preferences.empty()); answer->AddCodecs(negotiated_codecs); answer->set_protocol(offer->protocol()); if (!AddStreamParams(media_description_options.sender_options, session_options.rtcp_cname, ssrc_generator, current_streams, answer)) { return false; // Something went seriously wrong. } return true; } // Create a media content to be answered for the given |sender_options| // according to the given session_options.rtcp_mux, session_options.streams, // codecs, crypto, and current_streams. If we don't currently have crypto (in // current_cryptos) and it is enabled (in secure_policy), crypto is created // (according to crypto_suites). The codecs, rtcp_mux, and crypto are all // negotiated with the offer. If the negotiation fails, this method returns // false. The created content is added to the offer. static bool CreateMediaContentAnswer( const MediaContentDescription* offer, const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const SecurePolicy& sdes_policy, const CryptoParamsVec* current_cryptos, const RtpHeaderExtensions& local_rtp_extensions, UniqueRandomIdGenerator* ssrc_generator, bool enable_encrypted_rtp_header_extensions, StreamParamsVec* current_streams, bool bundle_enabled, MediaContentDescription* answer) { answer->set_extmap_allow_mixed_enum(offer->extmap_allow_mixed_enum()); RtpHeaderExtensions negotiated_rtp_extensions; NegotiateRtpHeaderExtensions( local_rtp_extensions, offer->rtp_header_extensions(), enable_encrypted_rtp_header_extensions, &negotiated_rtp_extensions); answer->set_rtp_header_extensions(negotiated_rtp_extensions); answer->set_rtcp_mux(session_options.rtcp_mux_enabled && offer->rtcp_mux()); if (answer->type() == cricket::MEDIA_TYPE_VIDEO) { answer->set_rtcp_reduced_size(offer->rtcp_reduced_size()); } answer->set_remote_estimate(offer->remote_estimate()); if (sdes_policy != SEC_DISABLED) { CryptoParams crypto; if (SelectCrypto(offer, bundle_enabled, session_options.crypto_options, &crypto)) { if (current_cryptos) { FindMatchingCrypto(*current_cryptos, crypto, &crypto); } answer->AddCrypto(crypto); } } if (answer->cryptos().empty() && sdes_policy == SEC_REQUIRED) { return false; } AddSimulcastToMediaDescription(media_description_options, answer); answer->set_direction(NegotiateRtpTransceiverDirection( offer->direction(), media_description_options.direction)); return true; } static bool IsMediaProtocolSupported(MediaType type, const std::string& protocol, bool secure_transport) { // Since not all applications serialize and deserialize the media protocol, // we will have to accept |protocol| to be empty. if (protocol.empty()) { return true; } if (type == MEDIA_TYPE_DATA) { // Check for SCTP, but also for RTP for RTP-based data channels. // TODO(pthatcher): Remove RTP once RTP-based data channels are gone. if (secure_transport) { // Most likely scenarios first. return IsDtlsSctp(protocol) || IsDtlsRtp(protocol) || IsPlainRtp(protocol); } else { return IsPlainSctp(protocol) || IsPlainRtp(protocol); } } // Allow for non-DTLS RTP protocol even when using DTLS because that's what // JSEP specifies. if (secure_transport) { // Most likely scenarios first. return IsDtlsRtp(protocol) || IsPlainRtp(protocol); } else { return IsPlainRtp(protocol); } } static void SetMediaProtocol(bool secure_transport, MediaContentDescription* desc) { if (!desc->cryptos().empty()) desc->set_protocol(kMediaProtocolSavpf); else if (secure_transport) desc->set_protocol(kMediaProtocolDtlsSavpf); else desc->set_protocol(kMediaProtocolAvpf); } // Gets the TransportInfo of the given |content_name| from the // |current_description|. If doesn't exist, returns a new one. static const TransportDescription* GetTransportDescription( const std::string& content_name, const SessionDescription* current_description) { const TransportDescription* desc = NULL; if (current_description) { const TransportInfo* info = current_description->GetTransportInfoByName(content_name); if (info) { desc = &info->description; } } return desc; } // Gets the current DTLS state from the transport description. static bool IsDtlsActive(const ContentInfo* content, const SessionDescription* current_description) { if (!content) { return false; } size_t msection_index = content - ¤t_description->contents()[0]; if (current_description->transport_infos().size() <= msection_index) { return false; } return current_description->transport_infos()[msection_index] .description.secure(); } void MediaDescriptionOptions::AddAudioSender( const std::string& track_id, const std::vector& stream_ids) { RTC_DCHECK(type == MEDIA_TYPE_AUDIO); AddSenderInternal(track_id, stream_ids, {}, SimulcastLayerList(), 1); } void MediaDescriptionOptions::AddVideoSender( const std::string& track_id, const std::vector& stream_ids, const std::vector& rids, const SimulcastLayerList& simulcast_layers, int num_sim_layers) { RTC_DCHECK(type == MEDIA_TYPE_VIDEO); RTC_DCHECK(rids.empty() || num_sim_layers == 0) << "RIDs are the compliant way to indicate simulcast."; RTC_DCHECK(ValidateSimulcastLayers(rids, simulcast_layers)); AddSenderInternal(track_id, stream_ids, rids, simulcast_layers, num_sim_layers); } void MediaDescriptionOptions::AddRtpDataChannel(const std::string& track_id, const std::string& stream_id) { RTC_DCHECK(type == MEDIA_TYPE_DATA); // TODO(steveanton): Is it the case that RtpDataChannel will never have more // than one stream? AddSenderInternal(track_id, {stream_id}, {}, SimulcastLayerList(), 1); } void MediaDescriptionOptions::AddSenderInternal( const std::string& track_id, const std::vector& stream_ids, const std::vector& rids, const SimulcastLayerList& simulcast_layers, int num_sim_layers) { // TODO(steveanton): Support any number of stream ids. RTC_CHECK(stream_ids.size() == 1U); SenderOptions options; options.track_id = track_id; options.stream_ids = stream_ids; options.simulcast_layers = simulcast_layers; options.rids = rids; options.num_sim_layers = num_sim_layers; sender_options.push_back(options); } bool MediaSessionOptions::HasMediaDescription(MediaType type) const { return absl::c_any_of( media_description_options, [type](const MediaDescriptionOptions& t) { return t.type == type; }); } MediaSessionDescriptionFactory::MediaSessionDescriptionFactory( const TransportDescriptionFactory* transport_desc_factory, rtc::UniqueRandomIdGenerator* ssrc_generator) : ssrc_generator_(ssrc_generator), transport_desc_factory_(transport_desc_factory) { RTC_DCHECK(ssrc_generator_); } MediaSessionDescriptionFactory::MediaSessionDescriptionFactory( ChannelManager* channel_manager, const TransportDescriptionFactory* transport_desc_factory, rtc::UniqueRandomIdGenerator* ssrc_generator) : MediaSessionDescriptionFactory(transport_desc_factory, ssrc_generator) { channel_manager->GetSupportedAudioSendCodecs(&audio_send_codecs_); channel_manager->GetSupportedAudioReceiveCodecs(&audio_recv_codecs_); channel_manager->GetSupportedVideoSendCodecs(&video_send_codecs_); channel_manager->GetSupportedVideoReceiveCodecs(&video_recv_codecs_); channel_manager->GetSupportedDataCodecs(&rtp_data_codecs_); ComputeAudioCodecsIntersectionAndUnion(); ComputeVideoCodecsIntersectionAndUnion(); } const AudioCodecs& MediaSessionDescriptionFactory::audio_sendrecv_codecs() const { return audio_sendrecv_codecs_; } const AudioCodecs& MediaSessionDescriptionFactory::audio_send_codecs() const { return audio_send_codecs_; } const AudioCodecs& MediaSessionDescriptionFactory::audio_recv_codecs() const { return audio_recv_codecs_; } void MediaSessionDescriptionFactory::set_audio_codecs( const AudioCodecs& send_codecs, const AudioCodecs& recv_codecs) { audio_send_codecs_ = send_codecs; audio_recv_codecs_ = recv_codecs; ComputeAudioCodecsIntersectionAndUnion(); } const VideoCodecs& MediaSessionDescriptionFactory::video_sendrecv_codecs() const { return video_sendrecv_codecs_; } const VideoCodecs& MediaSessionDescriptionFactory::video_send_codecs() const { return video_send_codecs_; } const VideoCodecs& MediaSessionDescriptionFactory::video_recv_codecs() const { return video_recv_codecs_; } void MediaSessionDescriptionFactory::set_video_codecs( const VideoCodecs& send_codecs, const VideoCodecs& recv_codecs) { video_send_codecs_ = send_codecs; video_recv_codecs_ = recv_codecs; ComputeVideoCodecsIntersectionAndUnion(); } static void RemoveUnifiedPlanExtensions(RtpHeaderExtensions* extensions) { RTC_DCHECK(extensions); extensions->erase( std::remove_if(extensions->begin(), extensions->end(), [](auto extension) { return extension.uri == webrtc::RtpExtension::kMidUri || extension.uri == webrtc::RtpExtension::kRidUri || extension.uri == webrtc::RtpExtension::kRepairedRidUri; }), extensions->end()); } RtpHeaderExtensions MediaSessionDescriptionFactory::filtered_rtp_header_extensions( RtpHeaderExtensions extensions) const { if (!is_unified_plan_) { RemoveUnifiedPlanExtensions(&extensions); } return extensions; } std::unique_ptr MediaSessionDescriptionFactory::CreateOffer( const MediaSessionOptions& session_options, const SessionDescription* current_description) const { // Must have options for each existing section. if (current_description) { RTC_DCHECK_LE(current_description->contents().size(), session_options.media_description_options.size()); } IceCredentialsIterator ice_credentials( session_options.pooled_ice_credentials); std::vector current_active_contents; if (current_description) { current_active_contents = GetActiveContents(*current_description, session_options); } StreamParamsVec current_streams = GetCurrentStreamParams(current_active_contents); AudioCodecs offer_audio_codecs; VideoCodecs offer_video_codecs; RtpDataCodecs offer_rtp_data_codecs; GetCodecsForOffer(current_active_contents, &offer_audio_codecs, &offer_video_codecs, &offer_rtp_data_codecs); if (!session_options.vad_enabled) { // If application doesn't want CN codecs in offer. StripCNCodecs(&offer_audio_codecs); } AudioVideoRtpHeaderExtensions extensions_with_ids = GetOfferedRtpHeaderExtensionsWithIds( current_active_contents, session_options.offer_extmap_allow_mixed, session_options.media_description_options); auto offer = std::make_unique(); // Iterate through the media description options, matching with existing media // descriptions in |current_description|. size_t msection_index = 0; for (const MediaDescriptionOptions& media_description_options : session_options.media_description_options) { const ContentInfo* current_content = nullptr; if (current_description && msection_index < current_description->contents().size()) { current_content = ¤t_description->contents()[msection_index]; // Media type must match unless this media section is being recycled. RTC_DCHECK(current_content->name != media_description_options.mid || IsMediaContentOfType(current_content, media_description_options.type)); } switch (media_description_options.type) { case MEDIA_TYPE_AUDIO: if (!AddAudioContentForOffer(media_description_options, session_options, current_content, current_description, extensions_with_ids.audio, offer_audio_codecs, ¤t_streams, offer.get(), &ice_credentials)) { return nullptr; } break; case MEDIA_TYPE_VIDEO: if (!AddVideoContentForOffer(media_description_options, session_options, current_content, current_description, extensions_with_ids.video, offer_video_codecs, ¤t_streams, offer.get(), &ice_credentials)) { return nullptr; } break; case MEDIA_TYPE_DATA: if (!AddDataContentForOffer(media_description_options, session_options, current_content, current_description, offer_rtp_data_codecs, ¤t_streams, offer.get(), &ice_credentials)) { return nullptr; } break; default: RTC_NOTREACHED(); } ++msection_index; } // Bundle the contents together, if we've been asked to do so, and update any // parameters that need to be tweaked for BUNDLE. if (session_options.bundle_enabled) { ContentGroup offer_bundle(GROUP_TYPE_BUNDLE); for (const ContentInfo& content : offer->contents()) { if (content.rejected) { continue; } // TODO(deadbeef): There are conditions that make bundling two media // descriptions together illegal. For example, they use the same payload // type to represent different codecs, or same IDs for different header // extensions. We need to detect this and not try to bundle those media // descriptions together. offer_bundle.AddContentName(content.name); } if (!offer_bundle.content_names().empty()) { offer->AddGroup(offer_bundle); if (!UpdateTransportInfoForBundle(offer_bundle, offer.get())) { RTC_LOG(LS_ERROR) << "CreateOffer failed to UpdateTransportInfoForBundle."; return nullptr; } if (!UpdateCryptoParamsForBundle(offer_bundle, offer.get())) { RTC_LOG(LS_ERROR) << "CreateOffer failed to UpdateCryptoParamsForBundle."; return nullptr; } } } // The following determines how to signal MSIDs to ensure compatibility with // older endpoints (in particular, older Plan B endpoints). if (is_unified_plan_) { // Be conservative and signal using both a=msid and a=ssrc lines. Unified // Plan answerers will look at a=msid and Plan B answerers will look at the // a=ssrc MSID line. offer->set_msid_signaling(cricket::kMsidSignalingMediaSection | cricket::kMsidSignalingSsrcAttribute); } else { // Plan B always signals MSID using a=ssrc lines. offer->set_msid_signaling(cricket::kMsidSignalingSsrcAttribute); } offer->set_extmap_allow_mixed(session_options.offer_extmap_allow_mixed); return offer; } std::unique_ptr MediaSessionDescriptionFactory::CreateAnswer( const SessionDescription* offer, const MediaSessionOptions& session_options, const SessionDescription* current_description) const { if (!offer) { return nullptr; } // Must have options for exactly as many sections as in the offer. RTC_DCHECK_EQ(offer->contents().size(), session_options.media_description_options.size()); IceCredentialsIterator ice_credentials( session_options.pooled_ice_credentials); std::vector current_active_contents; if (current_description) { current_active_contents = GetActiveContents(*current_description, session_options); } StreamParamsVec current_streams = GetCurrentStreamParams(current_active_contents); // Get list of all possible codecs that respects existing payload type // mappings and uses a single payload type space. // // Note that these lists may be further filtered for each m= section; this // step is done just to establish the payload type mappings shared by all // sections. AudioCodecs answer_audio_codecs; VideoCodecs answer_video_codecs; RtpDataCodecs answer_rtp_data_codecs; GetCodecsForAnswer(current_active_contents, *offer, &answer_audio_codecs, &answer_video_codecs, &answer_rtp_data_codecs); if (!session_options.vad_enabled) { // If application doesn't want CN codecs in answer. StripCNCodecs(&answer_audio_codecs); } auto answer = std::make_unique(); // If the offer supports BUNDLE, and we want to use it too, create a BUNDLE // group in the answer with the appropriate content names. const ContentGroup* offer_bundle = offer->GetGroupByName(GROUP_TYPE_BUNDLE); ContentGroup answer_bundle(GROUP_TYPE_BUNDLE); // Transport info shared by the bundle group. std::unique_ptr bundle_transport; answer->set_extmap_allow_mixed(offer->extmap_allow_mixed()); // Iterate through the media description options, matching with existing // media descriptions in |current_description|. size_t msection_index = 0; for (const MediaDescriptionOptions& media_description_options : session_options.media_description_options) { const ContentInfo* offer_content = &offer->contents()[msection_index]; // Media types and MIDs must match between the remote offer and the // MediaDescriptionOptions. RTC_DCHECK( IsMediaContentOfType(offer_content, media_description_options.type)); RTC_DCHECK(media_description_options.mid == offer_content->name); const ContentInfo* current_content = nullptr; if (current_description && msection_index < current_description->contents().size()) { current_content = ¤t_description->contents()[msection_index]; } RtpHeaderExtensions header_extensions = RtpHeaderExtensionsFromCapabilities( UnstoppedRtpHeaderExtensionCapabilities( media_description_options.header_extensions)); switch (media_description_options.type) { case MEDIA_TYPE_AUDIO: if (!AddAudioContentForAnswer( media_description_options, session_options, offer_content, offer, current_content, current_description, bundle_transport.get(), answer_audio_codecs, header_extensions, ¤t_streams, answer.get(), &ice_credentials)) { return nullptr; } break; case MEDIA_TYPE_VIDEO: if (!AddVideoContentForAnswer( media_description_options, session_options, offer_content, offer, current_content, current_description, bundle_transport.get(), answer_video_codecs, header_extensions, ¤t_streams, answer.get(), &ice_credentials)) { return nullptr; } break; case MEDIA_TYPE_DATA: if (!AddDataContentForAnswer( media_description_options, session_options, offer_content, offer, current_content, current_description, bundle_transport.get(), answer_rtp_data_codecs, ¤t_streams, answer.get(), &ice_credentials)) { return nullptr; } break; default: RTC_NOTREACHED(); } ++msection_index; // See if we can add the newly generated m= section to the BUNDLE group in // the answer. ContentInfo& added = answer->contents().back(); if (!added.rejected && session_options.bundle_enabled && offer_bundle && offer_bundle->HasContentName(added.name)) { answer_bundle.AddContentName(added.name); bundle_transport.reset( new TransportInfo(*answer->GetTransportInfoByName(added.name))); } } // If a BUNDLE group was offered, put a BUNDLE group in the answer even if // it's empty. RFC5888 says: // // A SIP entity that receives an offer that contains an "a=group" line // with semantics that are understood MUST return an answer that // contains an "a=group" line with the same semantics. if (offer_bundle) { answer->AddGroup(answer_bundle); } if (answer_bundle.FirstContentName()) { // Share the same ICE credentials and crypto params across all contents, // as BUNDLE requires. if (!UpdateTransportInfoForBundle(answer_bundle, answer.get())) { RTC_LOG(LS_ERROR) << "CreateAnswer failed to UpdateTransportInfoForBundle."; return NULL; } if (!UpdateCryptoParamsForBundle(answer_bundle, answer.get())) { RTC_LOG(LS_ERROR) << "CreateAnswer failed to UpdateCryptoParamsForBundle."; return NULL; } } // The following determines how to signal MSIDs to ensure compatibility with // older endpoints (in particular, older Plan B endpoints). if (is_unified_plan_) { // Unified Plan needs to look at what the offer included to find the most // compatible answer. if (offer->msid_signaling() == 0) { // We end up here in one of three cases: // 1. An empty offer. We'll reply with an empty answer so it doesn't // matter what we pick here. // 2. A data channel only offer. We won't add any MSIDs to the answer so // it also doesn't matter what we pick here. // 3. Media that's either sendonly or inactive from the remote endpoint. // We don't have any information to say whether the endpoint is Plan B // or Unified Plan, so be conservative and send both. answer->set_msid_signaling(cricket::kMsidSignalingMediaSection | cricket::kMsidSignalingSsrcAttribute); } else if (offer->msid_signaling() == (cricket::kMsidSignalingMediaSection | cricket::kMsidSignalingSsrcAttribute)) { // If both a=msid and a=ssrc MSID signaling methods were used, we're // probably talking to a Unified Plan endpoint so respond with just // a=msid. answer->set_msid_signaling(cricket::kMsidSignalingMediaSection); } else { // Otherwise, it's clear which method the offerer is using so repeat that // back to them. answer->set_msid_signaling(offer->msid_signaling()); } } else { // Plan B always signals MSID using a=ssrc lines. answer->set_msid_signaling(cricket::kMsidSignalingSsrcAttribute); } return answer; } const AudioCodecs& MediaSessionDescriptionFactory::GetAudioCodecsForOffer( const RtpTransceiverDirection& direction) const { switch (direction) { // If stream is inactive - generate list as if sendrecv. case RtpTransceiverDirection::kSendRecv: case RtpTransceiverDirection::kStopped: case RtpTransceiverDirection::kInactive: return audio_sendrecv_codecs_; case RtpTransceiverDirection::kSendOnly: return audio_send_codecs_; case RtpTransceiverDirection::kRecvOnly: return audio_recv_codecs_; } } const AudioCodecs& MediaSessionDescriptionFactory::GetAudioCodecsForAnswer( const RtpTransceiverDirection& offer, const RtpTransceiverDirection& answer) const { switch (answer) { // For inactive and sendrecv answers, generate lists as if we were to accept // the offer's direction. See RFC 3264 Section 6.1. case RtpTransceiverDirection::kSendRecv: case RtpTransceiverDirection::kStopped: case RtpTransceiverDirection::kInactive: return GetAudioCodecsForOffer( webrtc::RtpTransceiverDirectionReversed(offer)); case RtpTransceiverDirection::kSendOnly: return audio_send_codecs_; case RtpTransceiverDirection::kRecvOnly: return audio_recv_codecs_; } } const VideoCodecs& MediaSessionDescriptionFactory::GetVideoCodecsForOffer( const RtpTransceiverDirection& direction) const { switch (direction) { // If stream is inactive - generate list as if sendrecv. case RtpTransceiverDirection::kSendRecv: case RtpTransceiverDirection::kStopped: case RtpTransceiverDirection::kInactive: return video_sendrecv_codecs_; case RtpTransceiverDirection::kSendOnly: return video_send_codecs_; case RtpTransceiverDirection::kRecvOnly: return video_recv_codecs_; } } const VideoCodecs& MediaSessionDescriptionFactory::GetVideoCodecsForAnswer( const RtpTransceiverDirection& offer, const RtpTransceiverDirection& answer) const { switch (answer) { // For inactive and sendrecv answers, generate lists as if we were to accept // the offer's direction. See RFC 3264 Section 6.1. case RtpTransceiverDirection::kSendRecv: case RtpTransceiverDirection::kStopped: case RtpTransceiverDirection::kInactive: return GetVideoCodecsForOffer( webrtc::RtpTransceiverDirectionReversed(offer)); case RtpTransceiverDirection::kSendOnly: return video_send_codecs_; case RtpTransceiverDirection::kRecvOnly: return video_recv_codecs_; } } void MergeCodecsFromDescription( const std::vector& current_active_contents, AudioCodecs* audio_codecs, VideoCodecs* video_codecs, RtpDataCodecs* rtp_data_codecs, UsedPayloadTypes* used_pltypes) { for (const ContentInfo* content : current_active_contents) { if (IsMediaContentOfType(content, MEDIA_TYPE_AUDIO)) { const AudioContentDescription* audio = content->media_description()->as_audio(); MergeCodecs(audio->codecs(), audio_codecs, used_pltypes); } else if (IsMediaContentOfType(content, MEDIA_TYPE_VIDEO)) { const VideoContentDescription* video = content->media_description()->as_video(); MergeCodecs(video->codecs(), video_codecs, used_pltypes); } else if (IsMediaContentOfType(content, MEDIA_TYPE_DATA)) { const RtpDataContentDescription* data = content->media_description()->as_rtp_data(); if (data) { // Only relevant for RTP datachannels MergeCodecs(data->codecs(), rtp_data_codecs, used_pltypes); } } } } // Getting codecs for an offer involves these steps: // // 1. Construct payload type -> codec mappings for current description. // 2. Add any reference codecs that weren't already present // 3. For each individual media description (m= section), filter codecs based // on the directional attribute (happens in another method). void MediaSessionDescriptionFactory::GetCodecsForOffer( const std::vector& current_active_contents, AudioCodecs* audio_codecs, VideoCodecs* video_codecs, RtpDataCodecs* rtp_data_codecs) const { // First - get all codecs from the current description if the media type // is used. Add them to |used_pltypes| so the payload type is not reused if a // new media type is added. UsedPayloadTypes used_pltypes; MergeCodecsFromDescription(current_active_contents, audio_codecs, video_codecs, rtp_data_codecs, &used_pltypes); // Add our codecs that are not in the current description. MergeCodecs(all_audio_codecs_, audio_codecs, &used_pltypes); MergeCodecs(all_video_codecs_, video_codecs, &used_pltypes); MergeCodecs(rtp_data_codecs_, rtp_data_codecs, &used_pltypes); } // Getting codecs for an answer involves these steps: // // 1. Construct payload type -> codec mappings for current description. // 2. Add any codecs from the offer that weren't already present. // 3. Add any remaining codecs that weren't already present. // 4. For each individual media description (m= section), filter codecs based // on the directional attribute (happens in another method). void MediaSessionDescriptionFactory::GetCodecsForAnswer( const std::vector& current_active_contents, const SessionDescription& remote_offer, AudioCodecs* audio_codecs, VideoCodecs* video_codecs, RtpDataCodecs* rtp_data_codecs) const { // First - get all codecs from the current description if the media type // is used. Add them to |used_pltypes| so the payload type is not reused if a // new media type is added. UsedPayloadTypes used_pltypes; MergeCodecsFromDescription(current_active_contents, audio_codecs, video_codecs, rtp_data_codecs, &used_pltypes); // Second - filter out codecs that we don't support at all and should ignore. AudioCodecs filtered_offered_audio_codecs; VideoCodecs filtered_offered_video_codecs; RtpDataCodecs filtered_offered_rtp_data_codecs; for (const ContentInfo& content : remote_offer.contents()) { if (IsMediaContentOfType(&content, MEDIA_TYPE_AUDIO)) { const AudioContentDescription* audio = content.media_description()->as_audio(); for (const AudioCodec& offered_audio_codec : audio->codecs()) { if (!FindMatchingCodec(audio->codecs(), filtered_offered_audio_codecs, offered_audio_codec, nullptr) && FindMatchingCodec(audio->codecs(), all_audio_codecs_, offered_audio_codec, nullptr)) { filtered_offered_audio_codecs.push_back(offered_audio_codec); } } } else if (IsMediaContentOfType(&content, MEDIA_TYPE_VIDEO)) { const VideoContentDescription* video = content.media_description()->as_video(); for (const VideoCodec& offered_video_codec : video->codecs()) { if (!FindMatchingCodec(video->codecs(), filtered_offered_video_codecs, offered_video_codec, nullptr) && FindMatchingCodec(video->codecs(), all_video_codecs_, offered_video_codec, nullptr)) { filtered_offered_video_codecs.push_back(offered_video_codec); } } } else if (IsMediaContentOfType(&content, MEDIA_TYPE_DATA)) { const RtpDataContentDescription* data = content.media_description()->as_rtp_data(); if (data) { // RTP data. This part is inactive for SCTP data. for (const RtpDataCodec& offered_rtp_data_codec : data->codecs()) { if (!FindMatchingCodec( data->codecs(), filtered_offered_rtp_data_codecs, offered_rtp_data_codec, nullptr) && FindMatchingCodec(data->codecs(), rtp_data_codecs_, offered_rtp_data_codec, nullptr)) { filtered_offered_rtp_data_codecs.push_back(offered_rtp_data_codec); } } } } } // Add codecs that are not in the current description but were in // |remote_offer|. MergeCodecs(filtered_offered_audio_codecs, audio_codecs, &used_pltypes); MergeCodecs(filtered_offered_video_codecs, video_codecs, &used_pltypes); MergeCodecs(filtered_offered_rtp_data_codecs, rtp_data_codecs, &used_pltypes); } MediaSessionDescriptionFactory::AudioVideoRtpHeaderExtensions MediaSessionDescriptionFactory::GetOfferedRtpHeaderExtensionsWithIds( const std::vector& current_active_contents, bool extmap_allow_mixed, const std::vector& media_description_options) const { // All header extensions allocated from the same range to avoid potential // issues when using BUNDLE. // Strictly speaking the SDP attribute extmap_allow_mixed signals that the // receiver supports an RTP stream where one- and two-byte RTP header // extensions are mixed. For backwards compatibility reasons it's used in // WebRTC to signal that two-byte RTP header extensions are supported. UsedRtpHeaderExtensionIds used_ids( extmap_allow_mixed ? UsedRtpHeaderExtensionIds::IdDomain::kTwoByteAllowed : UsedRtpHeaderExtensionIds::IdDomain::kOneByteOnly); RtpHeaderExtensions all_regular_extensions; RtpHeaderExtensions all_encrypted_extensions; AudioVideoRtpHeaderExtensions offered_extensions; // First - get all extensions from the current description if the media type // is used. // Add them to |used_ids| so the local ids are not reused if a new media // type is added. for (const ContentInfo* content : current_active_contents) { if (IsMediaContentOfType(content, MEDIA_TYPE_AUDIO)) { const AudioContentDescription* audio = content->media_description()->as_audio(); MergeRtpHdrExts(audio->rtp_header_extensions(), &offered_extensions.audio, &all_regular_extensions, &all_encrypted_extensions, &used_ids); } else if (IsMediaContentOfType(content, MEDIA_TYPE_VIDEO)) { const VideoContentDescription* video = content->media_description()->as_video(); MergeRtpHdrExts(video->rtp_header_extensions(), &offered_extensions.video, &all_regular_extensions, &all_encrypted_extensions, &used_ids); } } // Add all encountered header extensions in the media description options that // are not in the current description. for (const auto& entry : media_description_options) { RtpHeaderExtensions filtered_extensions = filtered_rtp_header_extensions(UnstoppedOrPresentRtpHeaderExtensions( entry.header_extensions, all_regular_extensions, all_encrypted_extensions)); if (entry.type == MEDIA_TYPE_AUDIO) MergeRtpHdrExts(filtered_extensions, &offered_extensions.audio, &all_regular_extensions, &all_encrypted_extensions, &used_ids); else if (entry.type == MEDIA_TYPE_VIDEO) MergeRtpHdrExts(filtered_extensions, &offered_extensions.video, &all_regular_extensions, &all_encrypted_extensions, &used_ids); } // TODO(jbauch): Support adding encrypted header extensions to existing // sessions. if (enable_encrypted_rtp_header_extensions_ && current_active_contents.empty()) { AddEncryptedVersionsOfHdrExts(&offered_extensions.audio, &all_encrypted_extensions, &used_ids); AddEncryptedVersionsOfHdrExts(&offered_extensions.video, &all_encrypted_extensions, &used_ids); } return offered_extensions; } bool MediaSessionDescriptionFactory::AddTransportOffer( const std::string& content_name, const TransportOptions& transport_options, const SessionDescription* current_desc, SessionDescription* offer_desc, IceCredentialsIterator* ice_credentials) const { if (!transport_desc_factory_) return false; const TransportDescription* current_tdesc = GetTransportDescription(content_name, current_desc); std::unique_ptr new_tdesc( transport_desc_factory_->CreateOffer(transport_options, current_tdesc, ice_credentials)); if (!new_tdesc) { RTC_LOG(LS_ERROR) << "Failed to AddTransportOffer, content name=" << content_name; } offer_desc->AddTransportInfo(TransportInfo(content_name, *new_tdesc)); return true; } std::unique_ptr MediaSessionDescriptionFactory::CreateTransportAnswer( const std::string& content_name, const SessionDescription* offer_desc, const TransportOptions& transport_options, const SessionDescription* current_desc, bool require_transport_attributes, IceCredentialsIterator* ice_credentials) const { if (!transport_desc_factory_) return NULL; const TransportDescription* offer_tdesc = GetTransportDescription(content_name, offer_desc); const TransportDescription* current_tdesc = GetTransportDescription(content_name, current_desc); return transport_desc_factory_->CreateAnswer(offer_tdesc, transport_options, require_transport_attributes, current_tdesc, ice_credentials); } bool MediaSessionDescriptionFactory::AddTransportAnswer( const std::string& content_name, const TransportDescription& transport_desc, SessionDescription* answer_desc) const { answer_desc->AddTransportInfo(TransportInfo(content_name, transport_desc)); return true; } // |audio_codecs| = set of all possible codecs that can be used, with correct // payload type mappings // // |supported_audio_codecs| = set of codecs that are supported for the direction // of this m= section // // acd->codecs() = set of previously negotiated codecs for this m= section // // The payload types should come from audio_codecs, but the order should come // from acd->codecs() and then supported_codecs, to ensure that re-offers don't // change existing codec priority, and that new codecs are added with the right // priority. bool MediaSessionDescriptionFactory::AddAudioContentForOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* current_content, const SessionDescription* current_description, const RtpHeaderExtensions& audio_rtp_extensions, const AudioCodecs& audio_codecs, StreamParamsVec* current_streams, SessionDescription* desc, IceCredentialsIterator* ice_credentials) const { // Filter audio_codecs (which includes all codecs, with correctly remapped // payload types) based on transceiver direction. const AudioCodecs& supported_audio_codecs = GetAudioCodecsForOffer(media_description_options.direction); AudioCodecs filtered_codecs; if (!media_description_options.codec_preferences.empty()) { // Add the codecs from the current transceiver's codec preferences. // They override any existing codecs from previous negotiations. filtered_codecs = MatchCodecPreference( media_description_options.codec_preferences, supported_audio_codecs); } else { // Add the codecs from current content if it exists and is not rejected nor // recycled. if (current_content && !current_content->rejected && current_content->name == media_description_options.mid) { RTC_CHECK(IsMediaContentOfType(current_content, MEDIA_TYPE_AUDIO)); const AudioContentDescription* acd = current_content->media_description()->as_audio(); for (const AudioCodec& codec : acd->codecs()) { if (FindMatchingCodec(acd->codecs(), audio_codecs, codec, nullptr)) { filtered_codecs.push_back(codec); } } } // Add other supported audio codecs. AudioCodec found_codec; for (const AudioCodec& codec : supported_audio_codecs) { if (FindMatchingCodec(supported_audio_codecs, audio_codecs, codec, &found_codec) && !FindMatchingCodec(supported_audio_codecs, filtered_codecs, codec, nullptr)) { // Use the |found_codec| from |audio_codecs| because it has the // correctly mapped payload type. filtered_codecs.push_back(found_codec); } } } cricket::SecurePolicy sdes_policy = IsDtlsActive(current_content, current_description) ? cricket::SEC_DISABLED : secure(); auto audio = std::make_unique(); std::vector crypto_suites; GetSupportedAudioSdesCryptoSuiteNames(session_options.crypto_options, &crypto_suites); if (!CreateMediaContentOffer(media_description_options, session_options, filtered_codecs, sdes_policy, GetCryptos(current_content), crypto_suites, audio_rtp_extensions, ssrc_generator_, current_streams, audio.get())) { return false; } bool secure_transport = (transport_desc_factory_->secure() != SEC_DISABLED); SetMediaProtocol(secure_transport, audio.get()); audio->set_direction(media_description_options.direction); desc->AddContent(media_description_options.mid, MediaProtocolType::kRtp, media_description_options.stopped, std::move(audio)); if (!AddTransportOffer(media_description_options.mid, media_description_options.transport_options, current_description, desc, ice_credentials)) { return false; } return true; } // TODO(kron): This function is very similar to AddAudioContentForOffer. // Refactor to reuse shared code. bool MediaSessionDescriptionFactory::AddVideoContentForOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* current_content, const SessionDescription* current_description, const RtpHeaderExtensions& video_rtp_extensions, const VideoCodecs& video_codecs, StreamParamsVec* current_streams, SessionDescription* desc, IceCredentialsIterator* ice_credentials) const { // Filter video_codecs (which includes all codecs, with correctly remapped // payload types) based on transceiver direction. const VideoCodecs& supported_video_codecs = GetVideoCodecsForOffer(media_description_options.direction); VideoCodecs filtered_codecs; if (!media_description_options.codec_preferences.empty()) { // Add the codecs from the current transceiver's codec preferences. // They override any existing codecs from previous negotiations. filtered_codecs = MatchCodecPreference( media_description_options.codec_preferences, supported_video_codecs); } else { // Add the codecs from current content if it exists and is not rejected nor // recycled. if (current_content && !current_content->rejected && current_content->name == media_description_options.mid) { RTC_CHECK(IsMediaContentOfType(current_content, MEDIA_TYPE_VIDEO)); const VideoContentDescription* vcd = current_content->media_description()->as_video(); for (const VideoCodec& codec : vcd->codecs()) { if (FindMatchingCodec(vcd->codecs(), video_codecs, codec, nullptr)) { filtered_codecs.push_back(codec); } } } // Add other supported video codecs. VideoCodec found_codec; for (const VideoCodec& codec : supported_video_codecs) { if (FindMatchingCodec(supported_video_codecs, video_codecs, codec, &found_codec) && !FindMatchingCodec(supported_video_codecs, filtered_codecs, codec, nullptr)) { // Use the |found_codec| from |video_codecs| because it has the // correctly mapped payload type. filtered_codecs.push_back(found_codec); } } } if (session_options.raw_packetization_for_video) { for (VideoCodec& codec : filtered_codecs) { if (codec.GetCodecType() == VideoCodec::CODEC_VIDEO) { codec.packetization = kPacketizationParamRaw; } } } cricket::SecurePolicy sdes_policy = IsDtlsActive(current_content, current_description) ? cricket::SEC_DISABLED : secure(); auto video = std::make_unique(); std::vector crypto_suites; GetSupportedVideoSdesCryptoSuiteNames(session_options.crypto_options, &crypto_suites); if (!CreateMediaContentOffer(media_description_options, session_options, filtered_codecs, sdes_policy, GetCryptos(current_content), crypto_suites, video_rtp_extensions, ssrc_generator_, current_streams, video.get())) { return false; } video->set_bandwidth(kAutoBandwidth); bool secure_transport = (transport_desc_factory_->secure() != SEC_DISABLED); SetMediaProtocol(secure_transport, video.get()); video->set_direction(media_description_options.direction); desc->AddContent(media_description_options.mid, MediaProtocolType::kRtp, media_description_options.stopped, std::move(video)); if (!AddTransportOffer(media_description_options.mid, media_description_options.transport_options, current_description, desc, ice_credentials)) { return false; } return true; } bool MediaSessionDescriptionFactory::AddSctpDataContentForOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* current_content, const SessionDescription* current_description, StreamParamsVec* current_streams, SessionDescription* desc, IceCredentialsIterator* ice_credentials) const { auto data = std::make_unique(); bool secure_transport = (transport_desc_factory_->secure() != SEC_DISABLED); cricket::SecurePolicy sdes_policy = IsDtlsActive(current_content, current_description) ? cricket::SEC_DISABLED : secure(); std::vector crypto_suites; // SDES doesn't make sense for SCTP, so we disable it, and we only // get SDES crypto suites for RTP-based data channels. sdes_policy = cricket::SEC_DISABLED; // Unlike SetMediaProtocol below, we need to set the protocol // before we call CreateMediaContentOffer. Otherwise, // CreateMediaContentOffer won't know this is SCTP and will // generate SSRCs rather than SIDs. data->set_protocol(secure_transport ? kMediaProtocolUdpDtlsSctp : kMediaProtocolSctp); data->set_use_sctpmap(session_options.use_obsolete_sctp_sdp); data->set_max_message_size(kSctpSendBufferSize); if (!CreateContentOffer(media_description_options, session_options, sdes_policy, GetCryptos(current_content), crypto_suites, RtpHeaderExtensions(), ssrc_generator_, current_streams, data.get())) { return false; } desc->AddContent(media_description_options.mid, MediaProtocolType::kSctp, media_description_options.stopped, std::move(data)); if (!AddTransportOffer(media_description_options.mid, media_description_options.transport_options, current_description, desc, ice_credentials)) { return false; } return true; } bool MediaSessionDescriptionFactory::AddRtpDataContentForOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* current_content, const SessionDescription* current_description, const RtpDataCodecs& rtp_data_codecs, StreamParamsVec* current_streams, SessionDescription* desc, IceCredentialsIterator* ice_credentials) const { auto data = std::make_unique(); bool secure_transport = (transport_desc_factory_->secure() != SEC_DISABLED); cricket::SecurePolicy sdes_policy = IsDtlsActive(current_content, current_description) ? cricket::SEC_DISABLED : secure(); std::vector crypto_suites; GetSupportedDataSdesCryptoSuiteNames(session_options.crypto_options, &crypto_suites); if (!CreateMediaContentOffer(media_description_options, session_options, rtp_data_codecs, sdes_policy, GetCryptos(current_content), crypto_suites, RtpHeaderExtensions(), ssrc_generator_, current_streams, data.get())) { return false; } data->set_bandwidth(kDataMaxBandwidth); SetMediaProtocol(secure_transport, data.get()); desc->AddContent(media_description_options.mid, MediaProtocolType::kRtp, media_description_options.stopped, std::move(data)); if (!AddTransportOffer(media_description_options.mid, media_description_options.transport_options, current_description, desc, ice_credentials)) { return false; } return true; } bool MediaSessionDescriptionFactory::AddDataContentForOffer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* current_content, const SessionDescription* current_description, const RtpDataCodecs& rtp_data_codecs, StreamParamsVec* current_streams, SessionDescription* desc, IceCredentialsIterator* ice_credentials) const { bool is_sctp = (session_options.data_channel_type == DCT_SCTP); // If the DataChannel type is not specified, use the DataChannel type in // the current description. if (session_options.data_channel_type == DCT_NONE && current_content) { RTC_CHECK(IsMediaContentOfType(current_content, MEDIA_TYPE_DATA)); is_sctp = (current_content->media_description()->protocol() == kMediaProtocolSctp); } if (is_sctp) { return AddSctpDataContentForOffer( media_description_options, session_options, current_content, current_description, current_streams, desc, ice_credentials); } else { return AddRtpDataContentForOffer(media_description_options, session_options, current_content, current_description, rtp_data_codecs, current_streams, desc, ice_credentials); } } // |audio_codecs| = set of all possible codecs that can be used, with correct // payload type mappings // // |supported_audio_codecs| = set of codecs that are supported for the direction // of this m= section // // acd->codecs() = set of previously negotiated codecs for this m= section // // The payload types should come from audio_codecs, but the order should come // from acd->codecs() and then supported_codecs, to ensure that re-offers don't // change existing codec priority, and that new codecs are added with the right // priority. bool MediaSessionDescriptionFactory::AddAudioContentForAnswer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* offer_content, const SessionDescription* offer_description, const ContentInfo* current_content, const SessionDescription* current_description, const TransportInfo* bundle_transport, const AudioCodecs& audio_codecs, const RtpHeaderExtensions& default_audio_rtp_header_extensions, StreamParamsVec* current_streams, SessionDescription* answer, IceCredentialsIterator* ice_credentials) const { RTC_CHECK(IsMediaContentOfType(offer_content, MEDIA_TYPE_AUDIO)); const AudioContentDescription* offer_audio_description = offer_content->media_description()->as_audio(); std::unique_ptr audio_transport = CreateTransportAnswer( media_description_options.mid, offer_description, media_description_options.transport_options, current_description, bundle_transport != nullptr, ice_credentials); if (!audio_transport) { return false; } // Pick codecs based on the requested communications direction in the offer // and the selected direction in the answer. // Note these will be filtered one final time in CreateMediaContentAnswer. auto wants_rtd = media_description_options.direction; auto offer_rtd = offer_audio_description->direction(); auto answer_rtd = NegotiateRtpTransceiverDirection(offer_rtd, wants_rtd); AudioCodecs supported_audio_codecs = GetAudioCodecsForAnswer(offer_rtd, answer_rtd); AudioCodecs filtered_codecs; if (!media_description_options.codec_preferences.empty()) { filtered_codecs = MatchCodecPreference( media_description_options.codec_preferences, supported_audio_codecs); } else { // Add the codecs from current content if it exists and is not rejected nor // recycled. if (current_content && !current_content->rejected && current_content->name == media_description_options.mid) { RTC_CHECK(IsMediaContentOfType(current_content, MEDIA_TYPE_AUDIO)); const AudioContentDescription* acd = current_content->media_description()->as_audio(); for (const AudioCodec& codec : acd->codecs()) { if (FindMatchingCodec(acd->codecs(), audio_codecs, codec, nullptr)) { filtered_codecs.push_back(codec); } } } // Add other supported audio codecs. for (const AudioCodec& codec : supported_audio_codecs) { if (FindMatchingCodec(supported_audio_codecs, audio_codecs, codec, nullptr) && !FindMatchingCodec(supported_audio_codecs, filtered_codecs, codec, nullptr)) { // We should use the local codec with local parameters and the codec id // would be correctly mapped in |NegotiateCodecs|. filtered_codecs.push_back(codec); } } } bool bundle_enabled = offer_description->HasGroup(GROUP_TYPE_BUNDLE) && session_options.bundle_enabled; auto audio_answer = std::make_unique(); // Do not require or create SDES cryptos if DTLS is used. cricket::SecurePolicy sdes_policy = audio_transport->secure() ? cricket::SEC_DISABLED : secure(); if (!SetCodecsInAnswer(offer_audio_description, filtered_codecs, media_description_options, session_options, ssrc_generator_, current_streams, audio_answer.get())) { return false; } if (!CreateMediaContentAnswer( offer_audio_description, media_description_options, session_options, sdes_policy, GetCryptos(current_content), filtered_rtp_header_extensions(default_audio_rtp_header_extensions), ssrc_generator_, enable_encrypted_rtp_header_extensions_, current_streams, bundle_enabled, audio_answer.get())) { return false; // Fails the session setup. } bool secure = bundle_transport ? bundle_transport->description.secure() : audio_transport->secure(); bool rejected = media_description_options.stopped || offer_content->rejected || !IsMediaProtocolSupported(MEDIA_TYPE_AUDIO, audio_answer->protocol(), secure); if (!AddTransportAnswer(media_description_options.mid, *(audio_transport.get()), answer)) { return false; } if (rejected) { RTC_LOG(LS_INFO) << "Audio m= section '" << media_description_options.mid << "' being rejected in answer."; } answer->AddContent(media_description_options.mid, offer_content->type, rejected, std::move(audio_answer)); return true; } // TODO(kron): This function is very similar to AddAudioContentForAnswer. // Refactor to reuse shared code. bool MediaSessionDescriptionFactory::AddVideoContentForAnswer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* offer_content, const SessionDescription* offer_description, const ContentInfo* current_content, const SessionDescription* current_description, const TransportInfo* bundle_transport, const VideoCodecs& video_codecs, const RtpHeaderExtensions& default_video_rtp_header_extensions, StreamParamsVec* current_streams, SessionDescription* answer, IceCredentialsIterator* ice_credentials) const { RTC_CHECK(IsMediaContentOfType(offer_content, MEDIA_TYPE_VIDEO)); const VideoContentDescription* offer_video_description = offer_content->media_description()->as_video(); std::unique_ptr video_transport = CreateTransportAnswer( media_description_options.mid, offer_description, media_description_options.transport_options, current_description, bundle_transport != nullptr, ice_credentials); if (!video_transport) { return false; } // Pick codecs based on the requested communications direction in the offer // and the selected direction in the answer. // Note these will be filtered one final time in CreateMediaContentAnswer. auto wants_rtd = media_description_options.direction; auto offer_rtd = offer_video_description->direction(); auto answer_rtd = NegotiateRtpTransceiverDirection(offer_rtd, wants_rtd); VideoCodecs supported_video_codecs = GetVideoCodecsForAnswer(offer_rtd, answer_rtd); VideoCodecs filtered_codecs; if (!media_description_options.codec_preferences.empty()) { filtered_codecs = MatchCodecPreference( media_description_options.codec_preferences, supported_video_codecs); } else { // Add the codecs from current content if it exists and is not rejected nor // recycled. if (current_content && !current_content->rejected && current_content->name == media_description_options.mid) { RTC_CHECK(IsMediaContentOfType(current_content, MEDIA_TYPE_VIDEO)); const VideoContentDescription* vcd = current_content->media_description()->as_video(); for (const VideoCodec& codec : vcd->codecs()) { if (FindMatchingCodec(vcd->codecs(), video_codecs, codec, nullptr)) { filtered_codecs.push_back(codec); } } } // Add other supported video codecs. for (const VideoCodec& codec : supported_video_codecs) { if (FindMatchingCodec(supported_video_codecs, video_codecs, codec, nullptr) && !FindMatchingCodec(supported_video_codecs, filtered_codecs, codec, nullptr)) { // We should use the local codec with local parameters and the codec id // would be correctly mapped in |NegotiateCodecs|. filtered_codecs.push_back(codec); } } } if (session_options.raw_packetization_for_video) { for (VideoCodec& codec : filtered_codecs) { if (codec.GetCodecType() == VideoCodec::CODEC_VIDEO) { codec.packetization = kPacketizationParamRaw; } } } bool bundle_enabled = offer_description->HasGroup(GROUP_TYPE_BUNDLE) && session_options.bundle_enabled; auto video_answer = std::make_unique(); // Do not require or create SDES cryptos if DTLS is used. cricket::SecurePolicy sdes_policy = video_transport->secure() ? cricket::SEC_DISABLED : secure(); if (!SetCodecsInAnswer(offer_video_description, filtered_codecs, media_description_options, session_options, ssrc_generator_, current_streams, video_answer.get())) { return false; } if (!CreateMediaContentAnswer( offer_video_description, media_description_options, session_options, sdes_policy, GetCryptos(current_content), filtered_rtp_header_extensions(default_video_rtp_header_extensions), ssrc_generator_, enable_encrypted_rtp_header_extensions_, current_streams, bundle_enabled, video_answer.get())) { return false; // Failed the sessin setup. } bool secure = bundle_transport ? bundle_transport->description.secure() : video_transport->secure(); bool rejected = media_description_options.stopped || offer_content->rejected || !IsMediaProtocolSupported(MEDIA_TYPE_VIDEO, video_answer->protocol(), secure); if (!AddTransportAnswer(media_description_options.mid, *(video_transport.get()), answer)) { return false; } if (!rejected) { video_answer->set_bandwidth(kAutoBandwidth); } else { RTC_LOG(LS_INFO) << "Video m= section '" << media_description_options.mid << "' being rejected in answer."; } answer->AddContent(media_description_options.mid, offer_content->type, rejected, std::move(video_answer)); return true; } bool MediaSessionDescriptionFactory::AddDataContentForAnswer( const MediaDescriptionOptions& media_description_options, const MediaSessionOptions& session_options, const ContentInfo* offer_content, const SessionDescription* offer_description, const ContentInfo* current_content, const SessionDescription* current_description, const TransportInfo* bundle_transport, const RtpDataCodecs& rtp_data_codecs, StreamParamsVec* current_streams, SessionDescription* answer, IceCredentialsIterator* ice_credentials) const { std::unique_ptr data_transport = CreateTransportAnswer( media_description_options.mid, offer_description, media_description_options.transport_options, current_description, bundle_transport != nullptr, ice_credentials); if (!data_transport) { return false; } // Do not require or create SDES cryptos if DTLS is used. cricket::SecurePolicy sdes_policy = data_transport->secure() ? cricket::SEC_DISABLED : secure(); bool bundle_enabled = offer_description->HasGroup(GROUP_TYPE_BUNDLE) && session_options.bundle_enabled; RTC_CHECK(IsMediaContentOfType(offer_content, MEDIA_TYPE_DATA)); std::unique_ptr data_answer; if (offer_content->media_description()->as_sctp()) { // SCTP data content data_answer = std::make_unique(); const SctpDataContentDescription* offer_data_description = offer_content->media_description()->as_sctp(); // Respond with the offerer's proto, whatever it is. data_answer->as_sctp()->set_protocol(offer_data_description->protocol()); // Respond with our max message size or the remote max messsage size, // whichever is smaller. // 0 is treated specially - it means "I can accept any size". Since // we do not implement infinite size messages, reply with // kSctpSendBufferSize. if (offer_data_description->max_message_size() == 0) { data_answer->as_sctp()->set_max_message_size(kSctpSendBufferSize); } else { data_answer->as_sctp()->set_max_message_size(std::min( offer_data_description->max_message_size(), kSctpSendBufferSize)); } if (!CreateMediaContentAnswer( offer_data_description, media_description_options, session_options, sdes_policy, GetCryptos(current_content), RtpHeaderExtensions(), ssrc_generator_, enable_encrypted_rtp_header_extensions_, current_streams, bundle_enabled, data_answer.get())) { return false; // Fails the session setup. } // Respond with sctpmap if the offer uses sctpmap. bool offer_uses_sctpmap = offer_data_description->use_sctpmap(); data_answer->as_sctp()->set_use_sctpmap(offer_uses_sctpmap); } else { // RTP offer data_answer = std::make_unique(); const RtpDataContentDescription* offer_data_description = offer_content->media_description()->as_rtp_data(); RTC_CHECK(offer_data_description); if (!SetCodecsInAnswer(offer_data_description, rtp_data_codecs, media_description_options, session_options, ssrc_generator_, current_streams, data_answer->as_rtp_data())) { return false; } if (!CreateMediaContentAnswer( offer_data_description, media_description_options, session_options, sdes_policy, GetCryptos(current_content), RtpHeaderExtensions(), ssrc_generator_, enable_encrypted_rtp_header_extensions_, current_streams, bundle_enabled, data_answer.get())) { return false; // Fails the session setup. } } bool secure = bundle_transport ? bundle_transport->description.secure() : data_transport->secure(); bool rejected = session_options.data_channel_type == DCT_NONE || media_description_options.stopped || offer_content->rejected || !IsMediaProtocolSupported(MEDIA_TYPE_DATA, data_answer->protocol(), secure); if (!AddTransportAnswer(media_description_options.mid, *(data_transport.get()), answer)) { return false; } if (!rejected) { data_answer->set_bandwidth(kDataMaxBandwidth); } else { // RFC 3264 // The answer MUST contain the same number of m-lines as the offer. RTC_LOG(LS_INFO) << "Data is not supported in the answer."; } answer->AddContent(media_description_options.mid, offer_content->type, rejected, std::move(data_answer)); return true; } void MediaSessionDescriptionFactory::ComputeAudioCodecsIntersectionAndUnion() { audio_sendrecv_codecs_.clear(); all_audio_codecs_.clear(); // Compute the audio codecs union. for (const AudioCodec& send : audio_send_codecs_) { all_audio_codecs_.push_back(send); if (!FindMatchingCodec(audio_send_codecs_, audio_recv_codecs_, send, nullptr)) { // It doesn't make sense to have an RTX codec we support sending but not // receiving. RTC_DCHECK(!IsRtxCodec(send)); } } for (const AudioCodec& recv : audio_recv_codecs_) { if (!FindMatchingCodec(audio_recv_codecs_, audio_send_codecs_, recv, nullptr)) { all_audio_codecs_.push_back(recv); } } // Use NegotiateCodecs to merge our codec lists, since the operation is // essentially the same. Put send_codecs as the offered_codecs, which is the // order we'd like to follow. The reasoning is that encoding is usually more // expensive than decoding, and prioritizing a codec in the send list probably // means it's a codec we can handle efficiently. NegotiateCodecs(audio_recv_codecs_, audio_send_codecs_, &audio_sendrecv_codecs_, true); } void MediaSessionDescriptionFactory::ComputeVideoCodecsIntersectionAndUnion() { video_sendrecv_codecs_.clear(); all_video_codecs_.clear(); // Compute the video codecs union. for (const VideoCodec& send : video_send_codecs_) { all_video_codecs_.push_back(send); if (!FindMatchingCodec(video_send_codecs_, video_recv_codecs_, send, nullptr)) { // TODO(kron): This check is violated by the unit test: // MediaSessionDescriptionFactoryTest.RtxWithoutApt // Remove either the test or the check. // It doesn't make sense to have an RTX codec we support sending but not // receiving. // RTC_DCHECK(!IsRtxCodec(send)); } } for (const VideoCodec& recv : video_recv_codecs_) { if (!FindMatchingCodec(video_recv_codecs_, video_send_codecs_, recv, nullptr)) { all_video_codecs_.push_back(recv); } } // Use NegotiateCodecs to merge our codec lists, since the operation is // essentially the same. Put send_codecs as the offered_codecs, which is the // order we'd like to follow. The reasoning is that encoding is usually more // expensive than decoding, and prioritizing a codec in the send list probably // means it's a codec we can handle efficiently. NegotiateCodecs(video_recv_codecs_, video_send_codecs_, &video_sendrecv_codecs_, true); } bool IsMediaContent(const ContentInfo* content) { return (content && (content->type == MediaProtocolType::kRtp || content->type == MediaProtocolType::kSctp)); } bool IsAudioContent(const ContentInfo* content) { return IsMediaContentOfType(content, MEDIA_TYPE_AUDIO); } bool IsVideoContent(const ContentInfo* content) { return IsMediaContentOfType(content, MEDIA_TYPE_VIDEO); } bool IsDataContent(const ContentInfo* content) { return IsMediaContentOfType(content, MEDIA_TYPE_DATA); } const ContentInfo* GetFirstMediaContent(const ContentInfos& contents, MediaType media_type) { for (const ContentInfo& content : contents) { if (IsMediaContentOfType(&content, media_type)) { return &content; } } return nullptr; } const ContentInfo* GetFirstAudioContent(const ContentInfos& contents) { return GetFirstMediaContent(contents, MEDIA_TYPE_AUDIO); } const ContentInfo* GetFirstVideoContent(const ContentInfos& contents) { return GetFirstMediaContent(contents, MEDIA_TYPE_VIDEO); } const ContentInfo* GetFirstDataContent(const ContentInfos& contents) { return GetFirstMediaContent(contents, MEDIA_TYPE_DATA); } const ContentInfo* GetFirstMediaContent(const SessionDescription* sdesc, MediaType media_type) { if (sdesc == nullptr) { return nullptr; } return GetFirstMediaContent(sdesc->contents(), media_type); } const ContentInfo* GetFirstAudioContent(const SessionDescription* sdesc) { return GetFirstMediaContent(sdesc, MEDIA_TYPE_AUDIO); } const ContentInfo* GetFirstVideoContent(const SessionDescription* sdesc) { return GetFirstMediaContent(sdesc, MEDIA_TYPE_VIDEO); } const ContentInfo* GetFirstDataContent(const SessionDescription* sdesc) { return GetFirstMediaContent(sdesc, MEDIA_TYPE_DATA); } const MediaContentDescription* GetFirstMediaContentDescription( const SessionDescription* sdesc, MediaType media_type) { const ContentInfo* content = GetFirstMediaContent(sdesc, media_type); return (content ? content->media_description() : nullptr); } const AudioContentDescription* GetFirstAudioContentDescription( const SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_AUDIO); return desc ? desc->as_audio() : nullptr; } const VideoContentDescription* GetFirstVideoContentDescription( const SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_VIDEO); return desc ? desc->as_video() : nullptr; } const RtpDataContentDescription* GetFirstRtpDataContentDescription( const SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA); return desc ? desc->as_rtp_data() : nullptr; } const SctpDataContentDescription* GetFirstSctpDataContentDescription( const SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA); return desc ? desc->as_sctp() : nullptr; } // // Non-const versions of the above functions. // ContentInfo* GetFirstMediaContent(ContentInfos* contents, MediaType media_type) { for (ContentInfo& content : *contents) { if (IsMediaContentOfType(&content, media_type)) { return &content; } } return nullptr; } ContentInfo* GetFirstAudioContent(ContentInfos* contents) { return GetFirstMediaContent(contents, MEDIA_TYPE_AUDIO); } ContentInfo* GetFirstVideoContent(ContentInfos* contents) { return GetFirstMediaContent(contents, MEDIA_TYPE_VIDEO); } ContentInfo* GetFirstDataContent(ContentInfos* contents) { return GetFirstMediaContent(contents, MEDIA_TYPE_DATA); } ContentInfo* GetFirstMediaContent(SessionDescription* sdesc, MediaType media_type) { if (sdesc == nullptr) { return nullptr; } return GetFirstMediaContent(&sdesc->contents(), media_type); } ContentInfo* GetFirstAudioContent(SessionDescription* sdesc) { return GetFirstMediaContent(sdesc, MEDIA_TYPE_AUDIO); } ContentInfo* GetFirstVideoContent(SessionDescription* sdesc) { return GetFirstMediaContent(sdesc, MEDIA_TYPE_VIDEO); } ContentInfo* GetFirstDataContent(SessionDescription* sdesc) { return GetFirstMediaContent(sdesc, MEDIA_TYPE_DATA); } MediaContentDescription* GetFirstMediaContentDescription( SessionDescription* sdesc, MediaType media_type) { ContentInfo* content = GetFirstMediaContent(sdesc, media_type); return (content ? content->media_description() : nullptr); } AudioContentDescription* GetFirstAudioContentDescription( SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_AUDIO); return desc ? desc->as_audio() : nullptr; } VideoContentDescription* GetFirstVideoContentDescription( SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_VIDEO); return desc ? desc->as_video() : nullptr; } RtpDataContentDescription* GetFirstRtpDataContentDescription( SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA); return desc ? desc->as_rtp_data() : nullptr; } SctpDataContentDescription* GetFirstSctpDataContentDescription( SessionDescription* sdesc) { auto desc = GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA); return desc ? desc->as_sctp() : nullptr; } } // namespace cricket