| /* |
| * Copyright 2025 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/sdp_munging_detector.h" |
| |
| #include <cstddef> |
| #include <string> |
| |
| #include "absl/algorithm/container.h" |
| #include "api/jsep.h" |
| #include "api/media_types.h" |
| #include "api/uma_metrics.h" |
| #include "media/base/codec.h" |
| #include "media/base/media_constants.h" |
| #include "media/base/stream_params.h" |
| #include "p2p/base/transport_info.h" |
| #include "pc/session_description.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/logging.h" |
| |
| namespace webrtc { |
| |
| namespace { |
| |
| SdpMungingType DetermineTransportModification( |
| const cricket::TransportInfos& last_created_transport_infos, |
| const cricket::TransportInfos& transport_infos_to_set) { |
| if (last_created_transport_infos.size() != transport_infos_to_set.size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Number of transport-infos does not " |
| "match last created description."; |
| // Number of transports should always match number of contents so this |
| // should never happen. |
| return SdpMungingType::kNumberOfContents; |
| } |
| for (size_t i = 0; i < last_created_transport_infos.size(); i++) { |
| if (last_created_transport_infos[i].description.ice_ufrag != |
| transport_infos_to_set[i].description.ice_ufrag) { |
| RTC_LOG(LS_WARNING) |
| << "SDP munging: ice-ufrag does not match last created description."; |
| return SdpMungingType::kIceUfrag; |
| } |
| if (last_created_transport_infos[i].description.ice_pwd != |
| transport_infos_to_set[i].description.ice_pwd) { |
| RTC_LOG(LS_WARNING) |
| << "SDP munging: ice-pwd does not match last created description."; |
| return SdpMungingType::kIcePwd; |
| } |
| if (last_created_transport_infos[i].description.ice_mode != |
| transport_infos_to_set[i].description.ice_mode) { |
| RTC_LOG(LS_WARNING) |
| << "SDP munging: ice mode does not match last created description."; |
| return SdpMungingType::kIceMode; |
| } |
| if (last_created_transport_infos[i].description.connection_role != |
| transport_infos_to_set[i].description.connection_role) { |
| RTC_LOG(LS_WARNING) |
| << "SDP munging: DTLS role does not match last created description."; |
| return SdpMungingType::kDtlsSetup; |
| } |
| if (last_created_transport_infos[i].description.transport_options != |
| transport_infos_to_set[i].description.transport_options) { |
| RTC_LOG(LS_WARNING) << "SDP munging: ice_options does not match last " |
| "created description."; |
| return SdpMungingType::kIceOptions; |
| } |
| } |
| return SdpMungingType::kNoModification; |
| } |
| |
| SdpMungingType DetermineAudioSdpMungingType( |
| const cricket::MediaContentDescription* last_created_media_description, |
| const cricket::MediaContentDescription* media_description_to_set) { |
| RTC_DCHECK(last_created_media_description); |
| RTC_DCHECK(media_description_to_set); |
| // Removing codecs should be done via setCodecPreferences or negotiation, not |
| // munging. |
| if (last_created_media_description->codecs().size() > |
| media_description_to_set->codecs().size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: audio codecs removed."; |
| return SdpMungingType::kAudioCodecsRemoved; |
| } |
| // Adding audio codecs is measured after the more specific multiopus and L16 |
| // checks. |
| |
| // Opus stereo modification required to enabled stereo playout for opus. |
| bool created_opus_stereo = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamStereo, |
| &value) && |
| value == cricket::kParamValueTrue; |
| }) != last_created_media_description->codecs().end(); |
| bool set_opus_stereo = |
| absl::c_find_if( |
| media_description_to_set->codecs(), [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamStereo, &value) && |
| value == cricket::kParamValueTrue; |
| }) != media_description_to_set->codecs().end(); |
| if (!created_opus_stereo && set_opus_stereo) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Opus stereo enabled."; |
| return SdpMungingType::kAudioCodecsFmtpOpusStereo; |
| } |
| |
| // Nonstandard 5.1/7.1 opus variant. |
| bool created_multiopus = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| return codec.name == "multiopus"; |
| }) != last_created_media_description->codecs().end(); |
| bool set_multiopus = |
| absl::c_find_if(media_description_to_set->codecs(), |
| [](const cricket::Codec codec) { |
| return codec.name == "multiopus"; |
| }) != media_description_to_set->codecs().end(); |
| if (!created_multiopus && set_multiopus) { |
| RTC_LOG(LS_WARNING) << "SDP munging: multiopus enabled."; |
| return SdpMungingType::kAudioCodecsAddedMultiOpus; |
| } |
| |
| // L16. |
| bool created_l16 = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| return codec.name == cricket::kL16CodecName; |
| }) != last_created_media_description->codecs().end(); |
| bool set_l16 = absl::c_find_if(media_description_to_set->codecs(), |
| [](const cricket::Codec codec) { |
| return codec.name == cricket::kL16CodecName; |
| }) != media_description_to_set->codecs().end(); |
| if (!created_l16 && set_l16) { |
| RTC_LOG(LS_WARNING) << "SDP munging: L16 enabled."; |
| return SdpMungingType::kAudioCodecsAddedL16; |
| } |
| |
| // Audio NACK is not offered by default. |
| bool created_nack = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| return codec.HasFeedbackParam( |
| cricket::FeedbackParam(cricket::kRtcpFbParamNack)); |
| }) != last_created_media_description->codecs().end(); |
| bool set_nack = |
| absl::c_find_if(media_description_to_set->codecs(), |
| [](const cricket::Codec codec) { |
| return codec.HasFeedbackParam( |
| cricket::FeedbackParam(cricket::kRtcpFbParamNack)); |
| }) != media_description_to_set->codecs().end(); |
| if (!created_nack && set_nack) { |
| RTC_LOG(LS_WARNING) << "SDP munging: audio nack enabled."; |
| return SdpMungingType::kAudioCodecsRtcpFbAudioNack; |
| } |
| |
| if (last_created_media_description->codecs().size() < |
| media_description_to_set->codecs().size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: audio codecs added."; |
| return SdpMungingType::kAudioCodecsAdded; |
| } |
| |
| // Opus FEC is on by default. Should not be munged, can be controlled by |
| // the other side. |
| bool created_opus_fec = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamUseInbandFec, |
| &value) && |
| value == cricket::kParamValueTrue; |
| }) != last_created_media_description->codecs().end(); |
| bool set_opus_fec = |
| absl::c_find_if( |
| media_description_to_set->codecs(), [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamUseInbandFec, &value) && |
| value == cricket::kParamValueTrue; |
| }) != media_description_to_set->codecs().end(); |
| if (created_opus_fec && !set_opus_fec) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Opus FEC disabled."; |
| return SdpMungingType::kAudioCodecsFmtpOpusFec; |
| } |
| // Opus DTX is off by default. Should not be munged, can be controlled by |
| // the other side. |
| bool created_opus_dtx = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamUseDtx, |
| &value) && |
| value == cricket::kParamValueTrue; |
| }) != last_created_media_description->codecs().end(); |
| bool set_opus_dtx = |
| absl::c_find_if( |
| media_description_to_set->codecs(), [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamUseDtx, &value) && |
| value == cricket::kParamValueTrue; |
| }) != media_description_to_set->codecs().end(); |
| if (!created_opus_dtx && set_opus_dtx) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Opus DTX enabled."; |
| return SdpMungingType::kAudioCodecsFmtpOpusDtx; |
| } |
| |
| // Opus CBR is off by default. Should not be munged, can be controlled by |
| // the other side. |
| bool created_opus_cbr = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamCbr, |
| &value) && |
| value == cricket::kParamValueTrue; |
| }) != last_created_media_description->codecs().end(); |
| bool set_opus_cbr = |
| absl::c_find_if( |
| media_description_to_set->codecs(), [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kOpusCodecName && |
| codec.GetParam(cricket::kCodecParamCbr, &value) && |
| value == cricket::kParamValueTrue; |
| }) != media_description_to_set->codecs().end(); |
| if (!created_opus_cbr && set_opus_cbr) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Opus CBR enabled."; |
| return SdpMungingType::kAudioCodecsFmtpOpusCbr; |
| } |
| return SdpMungingType::kNoModification; |
| } |
| |
| SdpMungingType DetermineVideoSdpMungingType( |
| const cricket::MediaContentDescription* last_created_media_description, |
| const cricket::MediaContentDescription* media_description_to_set) { |
| RTC_DCHECK(last_created_media_description); |
| RTC_DCHECK(media_description_to_set); |
| // Removing codecs should be done via setCodecPreferences or negotiation, not |
| // munging. |
| if (last_created_media_description->codecs().size() > |
| media_description_to_set->codecs().size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: video codecs removed."; |
| return SdpMungingType::kVideoCodecsRemoved; |
| } |
| if (last_created_media_description->codecs().size() < |
| media_description_to_set->codecs().size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: video codecs added."; |
| return SdpMungingType::kVideoCodecsAdded; |
| } |
| |
| // Simulcast munging. |
| if (last_created_media_description->streams().size() == 1 && |
| media_description_to_set->streams().size() == 1) { |
| bool created_sim = |
| absl::c_find_if( |
| last_created_media_description->streams()[0].ssrc_groups, |
| [](const cricket::SsrcGroup group) { |
| return group.semantics == cricket::kSimSsrcGroupSemantics; |
| }) != |
| last_created_media_description->streams()[0].ssrc_groups.end(); |
| bool set_sim = |
| absl::c_find_if( |
| media_description_to_set->streams()[0].ssrc_groups, |
| [](const cricket::SsrcGroup group) { |
| return group.semantics == cricket::kSimSsrcGroupSemantics; |
| }) != media_description_to_set->streams()[0].ssrc_groups.end(); |
| if (!created_sim && set_sim) { |
| RTC_LOG(LS_WARNING) << "SDP munging: legacy simulcast group created."; |
| return SdpMungingType::kVideoCodecsLegacySimulcast; |
| } |
| } |
| |
| // sps-pps-idr-in-keyframe. |
| bool created_sps_pps_idr_in_keyframe = |
| absl::c_find_if(last_created_media_description->codecs(), |
| [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kH264CodecName && |
| codec.GetParam( |
| cricket::kH264FmtpSpsPpsIdrInKeyframe, |
| &value) && |
| value == cricket::kParamValueTrue; |
| }) != last_created_media_description->codecs().end(); |
| bool set_sps_pps_idr_in_keyframe = |
| absl::c_find_if( |
| media_description_to_set->codecs(), [](const cricket::Codec codec) { |
| std::string value; |
| return codec.name == cricket::kH264CodecName && |
| codec.GetParam(cricket::kH264FmtpSpsPpsIdrInKeyframe, |
| &value) && |
| value == cricket::kParamValueTrue; |
| }) != media_description_to_set->codecs().end(); |
| if (!created_sps_pps_idr_in_keyframe && set_sps_pps_idr_in_keyframe) { |
| RTC_LOG(LS_WARNING) << "SDP munging: sps-pps-idr-in-keyframe enabled."; |
| return SdpMungingType::kVideoCodecsFmtpH264SpsPpsIdrInKeyframe; |
| } |
| |
| return SdpMungingType::kNoModification; |
| } |
| |
| } // namespace |
| |
| // Determine if the SDP was modified between createOffer and |
| // setLocalDescription. |
| SdpMungingType DetermineSdpMungingType( |
| const SessionDescriptionInterface* sdesc, |
| const SessionDescriptionInterface* last_created_desc) { |
| if (!sdesc || !sdesc->description()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Failed to parse session description."; |
| return SdpMungingType::kUnknownModification; |
| } |
| |
| if (!last_created_desc || !last_created_desc->description()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: SetLocalDescription called without " |
| "CreateOffer or CreateAnswer."; |
| if (sdesc->GetType() == SdpType::kOffer) { |
| return SdpMungingType::kWithoutCreateOffer; |
| } else { // answer or pranswer. |
| return SdpMungingType::kWithoutCreateAnswer; |
| } |
| } |
| |
| // TODO: crbug.com/40567530 - we currently allow answer->pranswer |
| // so can not check sdesc->GetType() == last_created_desc->GetType(). |
| |
| SdpMungingType type; |
| |
| // TODO: crbug.com/40567530 - change Chromium so that pointer comparison works |
| // at least for implicit local description. |
| if (sdesc->description() == last_created_desc->description()) { |
| return SdpMungingType::kNoModification; |
| } |
| |
| // Validate contents. |
| const auto& last_created_contents = |
| last_created_desc->description()->contents(); |
| const auto& contents_to_set = sdesc->description()->contents(); |
| if (last_created_contents.size() != contents_to_set.size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: Number of m= sections does not match " |
| "last created description."; |
| return SdpMungingType::kNumberOfContents; |
| } |
| for (size_t i = 0; i < last_created_contents.size(); i++) { |
| // TODO: crbug.com/40567530 - more checks are needed here. |
| if (last_created_contents[i].mid() != contents_to_set[i].mid()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: mid does not match " |
| "last created description."; |
| return SdpMungingType::kMid; |
| } |
| |
| auto* last_created_media_description = |
| last_created_contents[i].media_description(); |
| auto* media_description_to_set = contents_to_set[i].media_description(); |
| if (!(last_created_media_description && media_description_to_set)) { |
| continue; |
| } |
| // Validate video and audio contents. |
| cricket::MediaType media_type = last_created_media_description->type(); |
| if (media_type == cricket::MEDIA_TYPE_VIDEO) { |
| type = DetermineVideoSdpMungingType(last_created_media_description, |
| media_description_to_set); |
| if (type != SdpMungingType::kNoModification) { |
| return type; |
| } |
| } else if (media_type == cricket::MEDIA_TYPE_AUDIO) { |
| type = DetermineAudioSdpMungingType(last_created_media_description, |
| media_description_to_set); |
| if (type != SdpMungingType::kNoModification) { |
| return type; |
| } |
| } |
| |
| // Validate codecs. We should have bailed out earlier if codecs were added |
| // or removed. |
| auto last_created_codecs = last_created_media_description->codecs(); |
| auto codecs_to_set = media_description_to_set->codecs(); |
| if (last_created_codecs.size() == codecs_to_set.size()) { |
| for (size_t i = 0; i < last_created_codecs.size(); i++) { |
| if (last_created_codecs[i] == codecs_to_set[i]) { |
| continue; |
| } |
| // Codec position swapped. |
| for (size_t j = i + 1; j < last_created_codecs.size(); j++) { |
| if (last_created_codecs[i] == codecs_to_set[j]) { |
| return media_type == cricket::MEDIA_TYPE_AUDIO |
| ? SdpMungingType::kAudioCodecsReordered |
| : SdpMungingType::kVideoCodecsReordered; |
| } |
| } |
| // Same codec but id changed. |
| if (last_created_codecs[i].name == codecs_to_set[i].name && |
| last_created_codecs[i].id != codecs_to_set[i].id) { |
| return SdpMungingType::kPayloadTypes; |
| } |
| if (last_created_codecs[i].params != codecs_to_set[i].params) { |
| return media_type == cricket::MEDIA_TYPE_AUDIO |
| ? SdpMungingType::kAudioCodecsFmtp |
| : SdpMungingType::kVideoCodecsFmtp; |
| } |
| if (last_created_codecs[i].feedback_params != |
| codecs_to_set[i].feedback_params) { |
| return media_type == cricket::MEDIA_TYPE_AUDIO |
| ? SdpMungingType::kAudioCodecsRtcpFb |
| : SdpMungingType::kVideoCodecsRtcpFb; |
| } |
| // At this point clockrate or channels changed. This should already be |
| // rejected later in the process so ignore for munging. |
| } |
| } |
| |
| // Validate media streams. |
| if (last_created_media_description->streams().size() != |
| media_description_to_set->streams().size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: streams size does not match last " |
| "created description."; |
| return SdpMungingType::kSsrcs; |
| } |
| for (size_t i = 0; i < last_created_media_description->streams().size(); |
| i++) { |
| if (last_created_media_description->streams()[i].ssrcs != |
| media_description_to_set->streams()[i].ssrcs) { |
| RTC_LOG(LS_WARNING) |
| << "SDP munging: SSRCs do not match last created description."; |
| return SdpMungingType::kSsrcs; |
| } |
| } |
| |
| // Validate RTP header extensions. |
| auto last_created_extensions = |
| last_created_media_description->rtp_header_extensions(); |
| auto extensions_to_set = media_description_to_set->rtp_header_extensions(); |
| if (last_created_extensions.size() < extensions_to_set.size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: RTP header extension added."; |
| return SdpMungingType::kRtpHeaderExtensionAdded; |
| } |
| if (last_created_extensions.size() > extensions_to_set.size()) { |
| RTC_LOG(LS_WARNING) << "SDP munging: RTP header extension removed."; |
| return SdpMungingType::kRtpHeaderExtensionRemoved; |
| } |
| for (size_t i = 0; i < last_created_extensions.size(); i++) { |
| if (!(last_created_extensions[i].id == extensions_to_set[i].id)) { |
| RTC_LOG(LS_WARNING) << "SDP munging: header extension modified."; |
| return SdpMungingType::kRtpHeaderExtensionModified; |
| } |
| } |
| } |
| |
| // Validate transport descriptions. |
| type = DetermineTransportModification( |
| last_created_desc->description()->transport_infos(), |
| sdesc->description()->transport_infos()); |
| if (type != SdpMungingType::kNoModification) { |
| return type; |
| } |
| |
| // TODO: crbug.com/40567530 - this serializes the descriptions back to a SDP |
| // string which is very complex and we not should be be forced to rely on |
| // string equality. |
| std::string serialized_description; |
| std::string serialized_last_description; |
| if (sdesc->ToString(&serialized_description) && |
| last_created_desc->ToString(&serialized_last_description) && |
| serialized_description == serialized_last_description) { |
| return SdpMungingType::kNoModification; |
| } |
| return SdpMungingType::kUnknownModification; |
| } |
| |
| } // namespace webrtc |
