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Dynamically assign ids to header extensions not enabled by default

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by creating an id collision and letting UsedIds resolve it.

Also avoid id=15 which is forbidden by
  https://www.rfc-editor.org/rfc/rfc8285#section-4.2
so might cause interop issues in offers to implementations
not supporting two-byte extensions.

BUG=webrtc:15378

Change-Id: I27926f065f8e396257294da7acf2be9802169805
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/319280
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#41696}
This commit is contained in:
Philipp Hancke 2024-02-07 18:01:39 +01:00 committed by WebRTC LUCI CQ
parent 3e613c2590
commit cea1c0b9a9
4 changed files with 21 additions and 16 deletions
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13
media/engine/webrtc_video_engine.cc
View file

@ -811,6 +811,8 @@ std::vector<VideoCodec> WebRtcVideoEngine::recv_codecs(bool include_rtx) const {
std::vector<webrtc::RtpHeaderExtensionCapability>
WebRtcVideoEngine::GetRtpHeaderExtensions() const {
std::vector<webrtc::RtpHeaderExtensionCapability> result;
// id is *not* incremented for non-default extensions, UsedIds needs to
// resolve conflicts.
int id = 1;
for (const auto& uri :
{webrtc::RtpExtension::kTimestampOffsetUri,
@ -825,27 +827,26 @@ WebRtcVideoEngine::GetRtpHeaderExtensions() const {
result.emplace_back(uri, id++, webrtc::RtpTransceiverDirection::kSendRecv);
}
for (const auto& uri : {webrtc::RtpExtension::kAbsoluteCaptureTimeUri}) {
result.emplace_back(uri, id++, webrtc::RtpTransceiverDirection::kStopped);
result.emplace_back(uri, id, webrtc::RtpTransceiverDirection::kStopped);
}
result.emplace_back(webrtc::RtpExtension::kGenericFrameDescriptorUri00, id++,
result.emplace_back(webrtc::RtpExtension::kGenericFrameDescriptorUri00, id,
IsEnabled(trials_, "WebRTC-GenericDescriptorAdvertised")
? webrtc::RtpTransceiverDirection::kSendRecv
: webrtc::RtpTransceiverDirection::kStopped);
result.emplace_back(
webrtc::RtpExtension::kDependencyDescriptorUri, id++,
webrtc::RtpExtension::kDependencyDescriptorUri, id,
IsEnabled(trials_, "WebRTC-DependencyDescriptorAdvertised")
? webrtc::RtpTransceiverDirection::kSendRecv
: webrtc::RtpTransceiverDirection::kStopped);
result.emplace_back(
webrtc::RtpExtension::kVideoLayersAllocationUri, id++,
webrtc::RtpExtension::kVideoLayersAllocationUri, id,
IsEnabled(trials_, "WebRTC-VideoLayersAllocationAdvertised")
? webrtc::RtpTransceiverDirection::kSendRecv
: webrtc::RtpTransceiverDirection::kStopped);
// VideoFrameTrackingId is a test-only extension.
if (IsEnabled(trials_, "WebRTC-VideoFrameTrackingIdAdvertised")) {
result.emplace_back(webrtc::RtpExtension::kVideoFrameTrackingIdUri, id++,
result.emplace_back(webrtc::RtpExtension::kVideoFrameTrackingIdUri, id,
webrtc::RtpTransceiverDirection::kSendRecv);
}
return result;

4
media/engine/webrtc_voice_engine.cc
View file

@ -643,6 +643,8 @@ std::vector<webrtc::RtpHeaderExtensionCapability>
WebRtcVoiceEngine::GetRtpHeaderExtensions() const {
RTC_DCHECK(signal_thread_checker_.IsCurrent());
std::vector<webrtc::RtpHeaderExtensionCapability> result;
// id is *not* incremented for non-default extensions, UsedIds needs to
// resolve conflicts.
int id = 1;
for (const auto& uri : {webrtc::RtpExtension::kAudioLevelUri,
webrtc::RtpExtension::kAbsSendTimeUri,
@ -651,7 +653,7 @@ WebRtcVoiceEngine::GetRtpHeaderExtensions() const {
result.emplace_back(uri, id++, webrtc::RtpTransceiverDirection::kSendRecv);
}
for (const auto& uri : {webrtc::RtpExtension::kAbsoluteCaptureTimeUri}) {
result.emplace_back(uri, id++, webrtc::RtpTransceiverDirection::kStopped);
result.emplace_back(uri, id, webrtc::RtpTransceiverDirection::kStopped);
}
return result;
}

11
pc/used_ids.h
View file

@ -147,15 +147,15 @@ class UsedRtpHeaderExtensionIds : public UsedIds<webrtc::RtpExtension> {
private:
// Returns the first unused id in reverse order from the max id of one byte
// header extensions. This hopefully reduce the risk of more collisions. We
// header extensions. This hopefully reduces the risk of more collisions. We
// want to change the default ids as little as possible. If no unused id is
// found and two byte header extensions are enabled (i.e.,
// `extmap_allow_mixed_` is true), search for unused ids from 15 to 255.
// `extmap_allow_mixed_` is true), search for unused ids from 16 to 255.
int FindUnusedId() override {
if (next_extension_id_ <=
webrtc::RtpExtension::kOneByteHeaderExtensionMaxId) {
// First search in reverse order from the max id of one byte header
// extensions.
// extensions (14).
while (IsIdUsed(next_extension_id_) &&
next_extension_id_ >= min_allowed_id_) {
--next_extension_id_;
@ -165,9 +165,10 @@ class UsedRtpHeaderExtensionIds : public UsedIds<webrtc::RtpExtension> {
if (id_domain_ == IdDomain::kTwoByteAllowed) {
if (next_extension_id_ < min_allowed_id_) {
// We have searched among all one-byte IDs without finding an unused ID,
// continue at the first two-byte ID.
// continue at the first two-byte ID (16; avoid 15 since it is somewhat
// special per https://www.rfc-editor.org/rfc/rfc8285#section-4.2
next_extension_id_ =
webrtc::RtpExtension::kOneByteHeaderExtensionMaxId + 1;
webrtc::RtpExtension::kOneByteHeaderExtensionMaxId + 2;
}
if (next_extension_id_ >

9
pc/used_ids_unittest.cc
View file

@ -119,7 +119,8 @@ TEST_F(UsedRtpHeaderExtensionIdsTest, TwoByteIdsAllowed) {
UsedRtpHeaderExtensionIds::IdDomain::kTwoByteAllowed);
// Fill all one byte IDs.
for (int i = 1; i < 15; ++i) {
for (int i = 1; i <= webrtc::RtpExtension::kOneByteHeaderExtensionMaxId;
++i) {
webrtc::RtpExtension id("", i);
used_ids.FindAndSetIdUsed(&id);
}
@ -131,11 +132,11 @@ TEST_F(UsedRtpHeaderExtensionIdsTest, TwoByteIdsAllowed) {
// Expect to reassign to two-byte header extension IDs.
used_ids.FindAndSetIdUsed(&id1_collision);
EXPECT_EQ(id1_collision.id, 15);
EXPECT_EQ(id1_collision.id, 16);
used_ids.FindAndSetIdUsed(&id2_collision);
EXPECT_EQ(id2_collision.id, 16);
EXPECT_EQ(id2_collision.id, 17);
used_ids.FindAndSetIdUsed(&id3_collision);
EXPECT_EQ(id3_collision.id, 17);
EXPECT_EQ(id3_collision.id, 18);
}
// Death tests.