cfaba8fd2d
by storing [[LastCreatedOffer]] / [[LastCreatedAnswer]] which are similar to the W3C equivalent but as description objects instead of serialized SDP strings. While rejecting all SDP munging is not feasible, this lets us measure and reject certain modifications gradually. Chromium metrics CL: https://chromium-review.googlesource.com/c/chromium/src/+/6089633 This is measured at three points during the lifetime of a peerconnection: * for the first SLD call * when the connection is first established * when the connection was established and is being closed Note that the "first" SDP munging detected is returned which may hide that something uses more than one modification. BUG=chromium:40567530 Change-Id: I964e3ee6e75f73b777d90556fac8691a6f3dc27f Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/370680 Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Henrik Boström <hbos@webrtc.org> Reviewed-by: Johannes Kron <kron@webrtc.org> Commit-Queue: Henrik Boström <hbos@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43741}
350 lines
15 KiB
C++
350 lines
15 KiB
C++
/*
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* Copyright 2025 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "pc/sdp_munging_detector.h"
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#include <cstddef>
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#include <string>
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#include "absl/algorithm/container.h"
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#include "api/jsep.h"
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#include "api/uma_metrics.h"
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#include "media/base/codec.h"
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#include "media/base/media_constants.h"
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#include "media/base/stream_params.h"
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#include "p2p/base/transport_info.h"
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#include "pc/session_description.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/logging.h"
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namespace webrtc {
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namespace {
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SdpMungingType DetermineTransportModification(
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const cricket::TransportInfos& last_created_transport_infos,
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const cricket::TransportInfos& transport_infos_to_set) {
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if (last_created_transport_infos.size() != transport_infos_to_set.size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: Number of transport-infos does not "
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"match last created description.";
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// Number of transports should always match number of contents so this
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// should never happen.
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return SdpMungingType::kNumberOfContents;
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}
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for (size_t i = 0; i < last_created_transport_infos.size(); i++) {
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if (last_created_transport_infos[i].description.ice_ufrag !=
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transport_infos_to_set[i].description.ice_ufrag) {
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RTC_LOG(LS_WARNING)
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<< "SDP munging: ice-ufrag does not match last created description.";
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return SdpMungingType::kIceUfrag;
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}
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if (last_created_transport_infos[i].description.ice_pwd !=
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transport_infos_to_set[i].description.ice_pwd) {
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RTC_LOG(LS_WARNING)
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<< "SDP munging: ice-pwd does not match last created description.";
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return SdpMungingType::kIcePwd;
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}
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if (last_created_transport_infos[i].description.ice_mode !=
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transport_infos_to_set[i].description.ice_mode) {
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RTC_LOG(LS_WARNING)
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<< "SDP munging: ice mode does not match last created description.";
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return SdpMungingType::kIceMode;
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}
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if (last_created_transport_infos[i].description.connection_role !=
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transport_infos_to_set[i].description.connection_role) {
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RTC_LOG(LS_WARNING)
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<< "SDP munging: DTLS role does not match last created description.";
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return SdpMungingType::kDtlsSetup;
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}
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if (last_created_transport_infos[i].description.transport_options !=
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transport_infos_to_set[i].description.transport_options) {
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RTC_LOG(LS_WARNING) << "SDP munging: ice_options does not match last "
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"created description.";
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return SdpMungingType::kIceOptions;
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}
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}
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return SdpMungingType::kNoModification;
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}
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SdpMungingType DetermineAudioSdpMungingType(
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const cricket::MediaContentDescription* last_created_media_description,
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const cricket::MediaContentDescription* media_description_to_set) {
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RTC_DCHECK(last_created_media_description);
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RTC_DCHECK(media_description_to_set);
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// Removing codecs should be done via setCodecPreferences or negotiation, not
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// munging.
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if (last_created_media_description->codecs().size() >
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media_description_to_set->codecs().size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: audio codecs removed.";
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return SdpMungingType::kAudioCodecsRemoved;
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}
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// Adding audio codecs is measured after the more specific multiopus and L16
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// checks.
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// Opus stereo modification required to enabled stereo playout for opus.
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bool created_opus_stereo =
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absl::c_find_if(last_created_media_description->codecs(),
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[](const cricket::Codec codec) {
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std::string value;
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return codec.name == cricket::kOpusCodecName &&
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codec.GetParam(cricket::kCodecParamStereo,
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&value) &&
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value == cricket::kParamValueTrue;
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}) != last_created_media_description->codecs().end();
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bool set_opus_stereo =
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absl::c_find_if(
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media_description_to_set->codecs(), [](const cricket::Codec codec) {
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std::string value;
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return codec.name == cricket::kOpusCodecName &&
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codec.GetParam(cricket::kCodecParamStereo, &value) &&
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value == cricket::kParamValueTrue;
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}) != media_description_to_set->codecs().end();
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if (!created_opus_stereo && set_opus_stereo) {
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RTC_LOG(LS_WARNING) << "SDP munging: Opus stereo enabled.";
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return SdpMungingType::kAudioCodecsFmtpOpusStereo;
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}
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// Nonstandard 5.1/7.1 opus variant.
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bool created_multiopus =
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absl::c_find_if(last_created_media_description->codecs(),
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[](const cricket::Codec codec) {
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return codec.name == "multiopus";
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}) != last_created_media_description->codecs().end();
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bool set_multiopus =
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absl::c_find_if(media_description_to_set->codecs(),
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[](const cricket::Codec codec) {
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return codec.name == "multiopus";
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}) != media_description_to_set->codecs().end();
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if (!created_multiopus && set_multiopus) {
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RTC_LOG(LS_WARNING) << "SDP munging: multiopus enabled.";
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return SdpMungingType::kAudioCodecsAddedMultiOpus;
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}
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// L16.
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bool created_l16 =
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absl::c_find_if(last_created_media_description->codecs(),
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[](const cricket::Codec codec) {
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return codec.name == cricket::kL16CodecName;
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}) != last_created_media_description->codecs().end();
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bool set_l16 = absl::c_find_if(media_description_to_set->codecs(),
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[](const cricket::Codec codec) {
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return codec.name == cricket::kL16CodecName;
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}) != media_description_to_set->codecs().end();
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if (!created_l16 && set_l16) {
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RTC_LOG(LS_WARNING) << "SDP munging: L16 enabled.";
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return SdpMungingType::kAudioCodecsAddedL16;
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}
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if (last_created_media_description->codecs().size() <
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media_description_to_set->codecs().size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: audio codecs added.";
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return SdpMungingType::kAudioCodecsAdded;
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}
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return SdpMungingType::kNoModification;
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}
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SdpMungingType DetermineVideoSdpMungingType(
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const cricket::MediaContentDescription* last_created_media_description,
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const cricket::MediaContentDescription* media_description_to_set) {
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RTC_DCHECK(last_created_media_description);
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RTC_DCHECK(media_description_to_set);
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// Removing codecs should be done via setCodecPreferences or negotiation, not
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// munging.
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if (last_created_media_description->codecs().size() >
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media_description_to_set->codecs().size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: video codecs removed.";
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return SdpMungingType::kVideoCodecsRemoved;
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}
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if (last_created_media_description->codecs().size() <
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media_description_to_set->codecs().size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: video codecs added.";
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return SdpMungingType::kVideoCodecsAdded;
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}
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// Simulcast munging.
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if (last_created_media_description->streams().size() == 1 &&
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media_description_to_set->streams().size() == 1) {
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bool created_sim =
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absl::c_find_if(
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last_created_media_description->streams()[0].ssrc_groups,
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[](const cricket::SsrcGroup group) {
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return group.semantics == cricket::kSimSsrcGroupSemantics;
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}) !=
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last_created_media_description->streams()[0].ssrc_groups.end();
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bool set_sim =
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absl::c_find_if(
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media_description_to_set->streams()[0].ssrc_groups,
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[](const cricket::SsrcGroup group) {
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return group.semantics == cricket::kSimSsrcGroupSemantics;
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}) != media_description_to_set->streams()[0].ssrc_groups.end();
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if (!created_sim && set_sim) {
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RTC_LOG(LS_WARNING) << "SDP munging: legacy simulcast group created.";
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return SdpMungingType::kVideoCodecsLegacySimulcast;
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}
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}
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// sps-pps-idr-in-keyframe.
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bool created_sps_pps_idr_in_keyframe =
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absl::c_find_if(last_created_media_description->codecs(),
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[](const cricket::Codec codec) {
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std::string value;
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return codec.name == cricket::kH264CodecName &&
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codec.GetParam(
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cricket::kH264FmtpSpsPpsIdrInKeyframe,
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&value) &&
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value == cricket::kParamValueTrue;
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}) != last_created_media_description->codecs().end();
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bool set_sps_pps_idr_in_keyframe =
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absl::c_find_if(
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media_description_to_set->codecs(), [](const cricket::Codec codec) {
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std::string value;
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return codec.name == cricket::kH264CodecName &&
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codec.GetParam(cricket::kH264FmtpSpsPpsIdrInKeyframe,
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&value) &&
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value == cricket::kParamValueTrue;
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}) != media_description_to_set->codecs().end();
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if (!created_sps_pps_idr_in_keyframe && set_sps_pps_idr_in_keyframe) {
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RTC_LOG(LS_WARNING) << "SDP munging: sps-pps-idr-in-keyframe enabled.";
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return SdpMungingType::kVideoCodecsFmtpH264SpsPpsIdrInKeyframe;
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}
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return SdpMungingType::kNoModification;
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}
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} // namespace
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// Determine if the SDP was modified between createOffer and
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// setLocalDescription.
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SdpMungingType DetermineSdpMungingType(
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const SessionDescriptionInterface* sdesc,
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const SessionDescriptionInterface* last_created_desc) {
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if (!sdesc || !sdesc->description()) {
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RTC_LOG(LS_WARNING) << "SDP munging: Failed to parse session description.";
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return SdpMungingType::kUnknownModification;
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}
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if (!last_created_desc || !last_created_desc->description()) {
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RTC_LOG(LS_WARNING) << "SDP munging: SetLocalDescription called without "
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"CreateOffer or CreateAnswer.";
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if (sdesc->GetType() == SdpType::kOffer) {
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return SdpMungingType::kWithoutCreateOffer;
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} else { // answer or pranswer.
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return SdpMungingType::kWithoutCreateAnswer;
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}
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}
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// TODO: crbug.com/40567530 - we currently allow answer->pranswer
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// so can not check sdesc->GetType() == last_created_desc->GetType().
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SdpMungingType type;
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// TODO: crbug.com/40567530 - change Chromium so that pointer comparison works
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// at least for implicit local description.
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if (sdesc->description() == last_created_desc->description()) {
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return SdpMungingType::kNoModification;
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}
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// Validate contents.
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const auto& last_created_contents =
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last_created_desc->description()->contents();
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const auto& contents_to_set = sdesc->description()->contents();
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if (last_created_contents.size() != contents_to_set.size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: Number of m= sections does not match "
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"last created description.";
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return SdpMungingType::kNumberOfContents;
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}
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for (size_t i = 0; i < last_created_contents.size(); i++) {
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// TODO: crbug.com/40567530 - more checks are needed here.
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if (last_created_contents[i].name != contents_to_set[i].name) {
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RTC_LOG(LS_WARNING) << "SDP munging: mid does not match "
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"last created description.";
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return SdpMungingType::kMid;
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}
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auto* last_created_media_description =
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last_created_contents[i].media_description();
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auto* media_description_to_set = contents_to_set[i].media_description();
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if (!(last_created_media_description && media_description_to_set)) {
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continue;
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}
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// Validate video and audio contents.
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if (last_created_media_description->as_video() != nullptr) {
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type = DetermineVideoSdpMungingType(last_created_media_description,
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media_description_to_set);
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if (type != SdpMungingType::kNoModification) {
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return type;
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}
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} else if (last_created_media_description->as_audio() != nullptr) {
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type = DetermineAudioSdpMungingType(last_created_media_description,
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media_description_to_set);
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if (type != SdpMungingType::kNoModification) {
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return type;
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}
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}
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// Validate media streams.
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if (last_created_media_description->streams().size() !=
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media_description_to_set->streams().size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: streams size does not match last "
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"created description.";
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return SdpMungingType::kSsrcs;
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}
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for (size_t i = 0; i < last_created_media_description->streams().size();
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i++) {
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if (last_created_media_description->streams()[i].ssrcs !=
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media_description_to_set->streams()[i].ssrcs) {
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RTC_LOG(LS_WARNING)
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<< "SDP munging: SSRCs do not match last created description.";
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return SdpMungingType::kSsrcs;
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}
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}
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// Validate RTP header extensions.
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auto last_created_extensions =
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last_created_media_description->rtp_header_extensions();
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auto extensions_to_set = media_description_to_set->rtp_header_extensions();
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if (last_created_extensions.size() < extensions_to_set.size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: RTP header extension added.";
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return SdpMungingType::kRtpHeaderExtensionAdded;
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}
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if (last_created_extensions.size() > extensions_to_set.size()) {
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RTC_LOG(LS_WARNING) << "SDP munging: RTP header extension removed.";
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return SdpMungingType::kRtpHeaderExtensionRemoved;
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}
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for (size_t i = 0; i < last_created_extensions.size(); i++) {
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if (!(last_created_extensions[i].id == extensions_to_set[i].id)) {
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RTC_LOG(LS_WARNING) << "SDP munging: header extension modified.";
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return SdpMungingType::kRtpHeaderExtensionModified;
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}
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}
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}
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// Validate transport descriptions.
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type = DetermineTransportModification(
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last_created_desc->description()->transport_infos(),
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sdesc->description()->transport_infos());
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if (type != SdpMungingType::kNoModification) {
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return type;
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}
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// TODO: crbug.com/40567530 - this serializes the descriptions back to a SDP
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// string which is very complex and we not should be be forced to rely on
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// string equality.
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std::string serialized_description;
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std::string serialized_last_description;
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if (sdesc->ToString(&serialized_description) &&
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last_created_desc->ToString(&serialized_last_description) &&
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serialized_description == serialized_last_description) {
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return SdpMungingType::kNoModification;
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}
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return SdpMungingType::kUnknownModification;
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}
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} // namespace webrtc
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