Only answer with non-stopped RTP header extensions

This extends the RTP header extension API usage to generating answers.

Also re-adds unit tests removed by the revert.

BUG=chromium:1051821

Change-Id: Ib754284e9a77cb49e22bea7072c475d240f2563b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/298740
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#39800}

pc/media_session.cc

@@ -1411,8 +1411,24 @@ static bool CreateMediaContentAnswer(
       enable_encrypted_rtp_header_extensions
           ? webrtc::RtpExtension::Filter::kPreferEncryptedExtension
           : webrtc::RtpExtension::Filter::kDiscardEncryptedExtension;
+
+  // Filter local extensions by capabilities and direction.
+  RtpHeaderExtensions local_rtp_extensions_to_reply_with;
+  for (auto extension_with_id : local_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. For now, do not include stopped extensions.
+        // See also crbug.com/webrtc/7477 about the general lack of direction.
+        if (extension.direction != RtpTransceiverDirection::kStopped) {
+          local_rtp_extensions_to_reply_with.push_back(extension_with_id);
+        }
+      }
+    }
+  }
   RtpHeaderExtensions negotiated_rtp_extensions;
-  NegotiateRtpHeaderExtensions(local_rtp_extensions,
+  NegotiateRtpHeaderExtensions(local_rtp_extensions_to_reply_with,
                                offer->rtp_header_extensions(),
                                extensions_filter, &negotiated_rtp_extensions);
   answer->set_rtp_header_extensions(negotiated_rtp_extensions);
@@ -2591,7 +2607,7 @@ bool MediaSessionDescriptionFactory::AddAudioContentForAnswer(
     const SessionDescription* current_description,
     const TransportInfo* bundle_transport,
     const AudioCodecs& audio_codecs,
-    const RtpHeaderExtensions& default_audio_rtp_header_extensions,
+    const RtpHeaderExtensions& rtp_header_extensions,
     StreamParamsVec* current_streams,
     SessionDescription* answer,
     IceCredentialsIterator* ice_credentials) const {
@@ -2679,7 +2695,7 @@ bool MediaSessionDescriptionFactory::AddAudioContentForAnswer(
   if (!CreateMediaContentAnswer(
           offer_audio_description, media_description_options, session_options,
           sdes_policy, GetCryptos(current_content),
-          filtered_rtp_header_extensions(default_audio_rtp_header_extensions),
+          filtered_rtp_header_extensions(rtp_header_extensions),
           ssrc_generator(), enable_encrypted_rtp_header_extensions_,
           current_streams, bundle_enabled, audio_answer.get())) {
     return false;  // Fails the session setup.

pc/media_session.h

@@ -285,7 +285,7 @@ class MediaSessionDescriptionFactory {
       const SessionDescription* current_description,
       const TransportInfo* bundle_transport,
       const AudioCodecs& audio_codecs,
-      const RtpHeaderExtensions& default_audio_rtp_header_extensions,
+      const RtpHeaderExtensions& rtp_header_extensions,
       StreamParamsVec* current_streams,
       SessionDescription* answer,
       IceCredentialsIterator* ice_credentials) const;
@@ -299,7 +299,7 @@ class MediaSessionDescriptionFactory {
       const SessionDescription* current_description,
       const TransportInfo* bundle_transport,
       const VideoCodecs& video_codecs,
-      const RtpHeaderExtensions& default_video_rtp_header_extensions,
+      const RtpHeaderExtensions& rtp_header_extensions,
       StreamParamsVec* current_streams,
       SessionDescription* answer,
       IceCredentialsIterator* ice_credentials) const;

pc/peer_connection_header_extension_unittest.cc

@@ -199,6 +199,39 @@ TEST_P(PeerConnectionHeaderExtensionTest, OffersUnstoppedModifiedExtensions) {
                           Field(&RtpExtension::uri, "uri3")));
 }
 
+TEST_P(PeerConnectionHeaderExtensionTest, AnswersUnstoppedModifiedExtensions) {
+  cricket::MediaType media_type;
+  SdpSemantics semantics;
+  std::tie(media_type, semantics) = GetParam();
+  if (semantics != SdpSemantics::kUnifiedPlan)
+    return;
+  std::unique_ptr<PeerConnectionWrapper> pc1 =
+      CreatePeerConnection(media_type, semantics);
+  std::unique_ptr<PeerConnectionWrapper> pc2 =
+      CreatePeerConnection(media_type, semantics);
+  auto transceiver1 = pc1->AddTransceiver(media_type);
+
+  auto offer = pc1->CreateOfferAndSetAsLocal(
+      PeerConnectionInterface::RTCOfferAnswerOptions());
+  pc2->SetRemoteDescription(std::move(offer));
+
+  ASSERT_EQ(pc2->pc()->GetTransceivers().size(), 1u);
+  auto transceiver2 = pc2->pc()->GetTransceivers()[0];
+  auto modified_extensions = transceiver2->GetHeaderExtensionsToNegotiate();
+  // Don't offer uri4.
+  modified_extensions[3].direction = RtpTransceiverDirection::kStopped;
+  transceiver2->SetHeaderExtensionsToNegotiate(modified_extensions);
+
+  auto answer = pc2->CreateAnswerAndSetAsLocal(
+      PeerConnectionInterface::RTCOfferAnswerOptions());
+  EXPECT_THAT(answer->description()
+                  ->contents()[0]
+                  .media_description()
+                  ->rtp_header_extensions(),
+              ElementsAre(Field(&RtpExtension::uri, "uri2"),
+                          Field(&RtpExtension::uri, "uri3")));
+}
+
 TEST_P(PeerConnectionHeaderExtensionTest, NegotiatedExtensionsAreAccessible) {
   cricket::MediaType media_type;
   SdpSemantics semantics;
@@ -235,6 +268,67 @@ TEST_P(PeerConnectionHeaderExtensionTest, NegotiatedExtensionsAreAccessible) {
                                 RtpTransceiverDirection::kStopped)));
 }
 
+TEST_P(PeerConnectionHeaderExtensionTest, OfferedExtensionsArePerTransceiver) {
+  cricket::MediaType media_type;
+  SdpSemantics semantics;
+  std::tie(media_type, semantics) = GetParam();
+  if (semantics != SdpSemantics::kUnifiedPlan)
+    return;
+  std::unique_ptr<PeerConnectionWrapper> pc1 =
+      CreatePeerConnection(media_type, semantics);
+  auto transceiver1 = pc1->AddTransceiver(media_type);
+  auto modified_extensions = transceiver1->GetHeaderExtensionsToNegotiate();
+  modified_extensions[3].direction = RtpTransceiverDirection::kStopped;
+  transceiver1->SetHeaderExtensionsToNegotiate(modified_extensions);
+  auto transceiver2 = pc1->AddTransceiver(media_type);
+
+  auto session_description = pc1->CreateOffer();
+  EXPECT_THAT(session_description->description()
+                  ->contents()[0]
+                  .media_description()
+                  ->rtp_header_extensions(),
+              ElementsAre(Field(&RtpExtension::uri, "uri2"),
+                          Field(&RtpExtension::uri, "uri3")));
+  EXPECT_THAT(session_description->description()
+                  ->contents()[1]
+                  .media_description()
+                  ->rtp_header_extensions(),
+              ElementsAre(Field(&RtpExtension::uri, "uri2"),
+                          Field(&RtpExtension::uri, "uri3"),
+                          Field(&RtpExtension::uri, "uri4")));
+}
+
+TEST_P(PeerConnectionHeaderExtensionTest, RemovalAfterRenegotiation) {
+  cricket::MediaType media_type;
+  SdpSemantics semantics;
+  std::tie(media_type, semantics) = GetParam();
+  if (semantics != SdpSemantics::kUnifiedPlan)
+    return;
+  std::unique_ptr<PeerConnectionWrapper> pc1 =
+      CreatePeerConnection(media_type, semantics);
+  std::unique_ptr<PeerConnectionWrapper> pc2 =
+      CreatePeerConnection(media_type, semantics);
+  auto transceiver1 = pc1->AddTransceiver(media_type);
+
+  auto offer = pc1->CreateOfferAndSetAsLocal(
+      PeerConnectionInterface::RTCOfferAnswerOptions());
+  pc2->SetRemoteDescription(std::move(offer));
+  auto answer = pc2->CreateAnswerAndSetAsLocal(
+      PeerConnectionInterface::RTCOfferAnswerOptions());
+  pc1->SetRemoteDescription(std::move(answer));
+
+  auto modified_extensions = transceiver1->GetHeaderExtensionsToNegotiate();
+  modified_extensions[3].direction = RtpTransceiverDirection::kStopped;
+  transceiver1->SetHeaderExtensionsToNegotiate(modified_extensions);
+  auto session_description = pc1->CreateOffer();
+  EXPECT_THAT(session_description->description()
+                  ->contents()[0]
+                  .media_description()
+                  ->rtp_header_extensions(),
+              ElementsAre(Field(&RtpExtension::uri, "uri2"),
+                          Field(&RtpExtension::uri, "uri3")));
+}
+
 TEST_P(PeerConnectionHeaderExtensionTest,
        StoppedByDefaultExtensionCanBeActivatedByRemoteSdp) {
   cricket::MediaType media_type;