Add support for TransportSequenceNumberV2 in SDP negotiation

TransportSequenceNumberV2 is an experimental feature that should
not be part of the default offer. However, if we receive an offer
with this extension we should respond that we support it.

Bug: webrtc:10264
Change-Id: Id2424d421361e5d71f3a608cb8f74b63645c264a
Reviewed-on: https://webrtc-review.googlesource.com/c/123783
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26817}

api/rtp_parameters.cc

@@ -167,6 +167,7 @@ constexpr int RtpExtension::kOneByteHeaderExtensionMaxValueSize;
 bool RtpExtension::IsSupportedForAudio(const std::string& uri) {
   return uri == webrtc::RtpExtension::kAudioLevelUri ||
          uri == webrtc::RtpExtension::kTransportSequenceNumberUri ||
+         uri == webrtc::RtpExtension::kTransportSequenceNumberV2Uri ||
          uri == webrtc::RtpExtension::kMidUri ||
          uri == webrtc::RtpExtension::kRidUri ||
          uri == webrtc::RtpExtension::kRepairedRidUri;
@@ -177,6 +178,7 @@ bool RtpExtension::IsSupportedForVideo(const std::string& uri) {
          uri == webrtc::RtpExtension::kAbsSendTimeUri ||
          uri == webrtc::RtpExtension::kVideoRotationUri ||
          uri == webrtc::RtpExtension::kTransportSequenceNumberUri ||
+         uri == webrtc::RtpExtension::kTransportSequenceNumberV2Uri ||
          uri == webrtc::RtpExtension::kPlayoutDelayUri ||
          uri == webrtc::RtpExtension::kVideoContentTypeUri ||
          uri == webrtc::RtpExtension::kVideoTimingUri ||
@@ -202,6 +204,7 @@ bool RtpExtension::IsEncryptionSupported(const std::string& uri) {
 #endif
          uri == webrtc::RtpExtension::kVideoRotationUri ||
          uri == webrtc::RtpExtension::kTransportSequenceNumberUri ||
+         uri == webrtc::RtpExtension::kTransportSequenceNumberV2Uri ||
          uri == webrtc::RtpExtension::kPlayoutDelayUri ||
          uri == webrtc::RtpExtension::kVideoContentTypeUri ||
          uri == webrtc::RtpExtension::kMidUri ||

pc/media_session.cc

@@ -1091,16 +1091,41 @@ static void NegotiateRtpHeaderExtensions(
     const RtpHeaderExtensions& local_extensions,
     const RtpHeaderExtensions& offered_extensions,
     bool enable_encrypted_rtp_header_extensions,
-    RtpHeaderExtensions* negotiated_extenstions) {
+    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);
+
   for (const webrtc::RtpExtension& ours : local_extensions) {
     webrtc::RtpExtension theirs;
     if (FindByUriWithEncryptionPreference(
             offered_extensions, ours, enable_encrypted_rtp_header_extensions,
             &theirs)) {
-      // We respond with their RTP header extension id.
+      if (transport_sequence_number_v2_offer &&
-      negotiated_extenstions->push_back(theirs);
+          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.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-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);
+  }
 }
 
 static void StripCNCodecs(AudioCodecs* audio_codecs) {

pc/media_session_unittest.cc

@@ -213,6 +213,27 @@ static const RtpExtension kVideoRtpExtensionEncryptedAnswer[] = {
     RtpExtension("urn:ietf:params:rtp-hdrext:toffset", 11, true),
 };
 
+static const RtpExtension kRtpExtensionTransportSequenceNumber01[] = {
+    RtpExtension("http://www.ietf.org/id/"
+                 "draft-holmer-rmcat-transport-wide-cc-extensions-01",
+                 1),
+};
+
+static const RtpExtension kRtpExtensionTransportSequenceNumber01And02[] = {
+    RtpExtension("http://www.ietf.org/id/"
+                 "draft-holmer-rmcat-transport-wide-cc-extensions-01",
+                 1),
+    RtpExtension("http://www.ietf.org/id/"
+                 "draft-holmer-rmcat-transport-wide-cc-extensions-02",
+                 2),
+};
+
+static const RtpExtension kRtpExtensionTransportSequenceNumber02[] = {
+    RtpExtension("http://www.ietf.org/id/"
+                 "draft-holmer-rmcat-transport-wide-cc-extensions-02",
+                 2),
+};
+
 static const uint32_t kSimulcastParamsSsrc[] = {10, 11, 20, 21, 30, 31};
 static const uint32_t kSimSsrc[] = {10, 20, 30};
 static const uint32_t kFec1Ssrc[] = {10, 11};
@@ -689,6 +710,30 @@ class MediaSessionDescriptionFactoryTest : public testing::Test {
     EXPECT_EQ(cricket::kMediaProtocolSavpf, vcd->protocol());
   }
 
+  void TestTransportSequenceNumberNegotiation(
+      const cricket::RtpHeaderExtensions& local,
+      const cricket::RtpHeaderExtensions& offered,
+      const cricket::RtpHeaderExtensions& expectedAnswer) {
+    MediaSessionOptions opts;
+    AddAudioVideoSections(RtpTransceiverDirection::kRecvOnly, &opts);
+    f1_.set_audio_rtp_header_extensions(offered);
+    f1_.set_video_rtp_header_extensions(offered);
+    f2_.set_audio_rtp_header_extensions(local);
+    f2_.set_video_rtp_header_extensions(local);
+
+    std::unique_ptr<SessionDescription> offer = f1_.CreateOffer(opts, NULL);
+    ASSERT_TRUE(offer.get() != NULL);
+    std::unique_ptr<SessionDescription> answer =
+        f2_.CreateAnswer(offer.get(), opts, NULL);
+
+    EXPECT_EQ(
+        expectedAnswer,
+        GetFirstAudioContentDescription(answer.get())->rtp_header_extensions());
+    EXPECT_EQ(
+        expectedAnswer,
+        GetFirstVideoContentDescription(answer.get())->rtp_header_extensions());
+  }
+
  protected:
   UniqueRandomIdGenerator ssrc_generator1;
   UniqueRandomIdGenerator ssrc_generator2;
@@ -1506,6 +1551,32 @@ TEST_F(MediaSessionDescriptionFactoryTest, TestOfferAnswerWithRtpExtensions) {
       GetFirstVideoContentDescription(answer.get())->rtp_header_extensions());
 }
 
+// Create a audio/video offer and answer and ensure that the
+// TransportSequenceNumber RTP header extensions are handled correctly. 02 is
+// supported and should take precedence even though not listed among locally
+// supported extensions.
+TEST_F(MediaSessionDescriptionFactoryTest,
+       TestOfferAnswerWithTransportSequenceNumberInOffer) {
+  TestTransportSequenceNumberNegotiation(
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber01),   // Local.
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber01),   // Offer.
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber01));  // Expected answer.
+}
+TEST_F(MediaSessionDescriptionFactoryTest,
+       TestOfferAnswerWithTransportSequenceNumber01And02InOffer) {
+  TestTransportSequenceNumberNegotiation(
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber01),       // Local.
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber01And02),  // Offer.
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber02));  // Expected answer.
+}
+TEST_F(MediaSessionDescriptionFactoryTest,
+       TestOfferAnswerWithTransportSequenceNumber02InOffer) {
+  TestTransportSequenceNumberNegotiation(
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber01),   // Local.
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber02),   // Offer.
+      MAKE_VECTOR(kRtpExtensionTransportSequenceNumber02));  // Expected answer.
+}
+
 TEST_F(MediaSessionDescriptionFactoryTest,
        TestOfferAnswerWithEncryptedRtpExtensionsBoth) {
   MediaSessionOptions opts;