From ae1ad04077c819ca3c3fff4a3432d1e1b7f6ff6f Mon Sep 17 00:00:00 2001
From: Per K <perkj@webrtc.org>
Date: Tue, 3 Dec 2024 15:54:58 +0000
Subject: [PATCH] Add support for receiving congestion control messages to rtcp
 transceiver

Congestion control feedback messages follow RFC 8888.

BUG: webrtc:42225697
Change-Id: If7e55249ac479636c0bab5cbcf96e70c1976a51d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/370161
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43486}
---
 .../rtp_rtcp/source/rtcp_transceiver_impl.cc  | 18 +++++++++++++
 .../rtp_rtcp/source/rtcp_transceiver_impl.h   |  3 +++
 .../source/rtcp_transceiver_impl_unittest.cc  | 26 +++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/modules/rtp_rtcp/source/rtcp_transceiver_impl.cc b/modules/rtp_rtcp/source/rtcp_transceiver_impl.cc
index f3f6d5142d..df6e625d41 100644
--- a/modules/rtp_rtcp/source/rtcp_transceiver_impl.cc
+++ b/modules/rtp_rtcp/source/rtcp_transceiver_impl.cc
@@ -23,6 +23,7 @@
 #include "modules/rtp_rtcp/source/rtcp_packet.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/bye.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
+#include "modules/rtp_rtcp/source/rtcp_packet/congestion_control_feedback.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/extended_reports.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/fir.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/nack.h"
@@ -464,6 +465,9 @@ void RtcpTransceiverImpl::HandleRtpFeedback(
     case rtcp::TransportFeedback::kFeedbackMessageType:
       HandleTransportFeedback(rtcp_packet_header, now);
       break;
+    case rtcp::CongestionControlFeedback::kFeedbackMessageType:
+      HandleCongestionControlFeedback(rtcp_packet_header, now);
+      break;
   }
 }
 
@@ -493,6 +497,20 @@ void RtcpTransceiverImpl::HandleTransportFeedback(
   }
 }
 
+void RtcpTransceiverImpl::HandleCongestionControlFeedback(
+    const rtcp::CommonHeader& rtcp_packet_header,
+    Timestamp now) {
+  RTC_DCHECK_EQ(rtcp_packet_header.fmt(),
+                rtcp::CongestionControlFeedback::kFeedbackMessageType);
+  if (config_.network_link_observer == nullptr) {
+    return;
+  }
+  rtcp::CongestionControlFeedback feedback;
+  if (feedback.Parse(rtcp_packet_header)) {
+    config_.network_link_observer->OnCongestionControlFeedback(now, feedback);
+  }
+}
+
 void RtcpTransceiverImpl::HandleExtendedReports(
     const rtcp::CommonHeader& rtcp_packet_header,
     Timestamp now) {
diff --git a/modules/rtp_rtcp/source/rtcp_transceiver_impl.h b/modules/rtp_rtcp/source/rtcp_transceiver_impl.h
index d4f12dc4ee..24710247de 100644
--- a/modules/rtp_rtcp/source/rtcp_transceiver_impl.h
+++ b/modules/rtp_rtcp/source/rtcp_transceiver_impl.h
@@ -114,6 +114,9 @@ class RtcpTransceiverImpl {
   void HandleNack(const rtcp::CommonHeader& rtcp_packet_header);
   void HandleTransportFeedback(const rtcp::CommonHeader& rtcp_packet_header,
                                Timestamp now);
+  void HandleCongestionControlFeedback(
+      const rtcp::CommonHeader& rtcp_packet_header,
+      Timestamp now);
   void HandleExtendedReports(const rtcp::CommonHeader& rtcp_packet_header,
                              Timestamp now);
   // Extended Reports blocks handlers.
diff --git a/modules/rtp_rtcp/source/rtcp_transceiver_impl_unittest.cc b/modules/rtp_rtcp/source/rtcp_transceiver_impl_unittest.cc
index 988bcccd5b..57f19d13b4 100644
--- a/modules/rtp_rtcp/source/rtcp_transceiver_impl_unittest.cc
+++ b/modules/rtp_rtcp/source/rtcp_transceiver_impl_unittest.cc
@@ -30,6 +30,7 @@
 #include "modules/rtp_rtcp/source/rtcp_packet/app.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/bye.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/compound_packet.h"
+#include "modules/rtp_rtcp/source/rtcp_packet/congestion_control_feedback.h"
 #include "system_wrappers/include/clock.h"
 #include "test/gmock.h"
 #include "test/gtest.h"
@@ -1403,6 +1404,31 @@ TEST_F(RtcpTransceiverImplTest, ParsesTransportFeedback) {
   rtcp_transceiver.ReceivePacket(tb.Build(), receive_time);
 }
 
+TEST_F(RtcpTransceiverImplTest, ParsesCongestionControlFeedback) {
+  MockNetworkLinkRtcpObserver link_observer;
+  RtcpTransceiverConfig config = DefaultTestConfig();
+  config.network_link_observer = &link_observer;
+  const uint32_t receive_time_ntp = 5678;
+  Timestamp receive_time = Timestamp::Seconds(9843);
+  RtcpTransceiverImpl rtcp_transceiver(config);
+
+  EXPECT_CALL(link_observer, OnCongestionControlFeedback(receive_time, _))
+      .WillOnce(WithArg<1>([](const rtcp::CongestionControlFeedback& message) {
+        EXPECT_EQ(message.report_timestamp_compact_ntp(), 5678u);
+        EXPECT_THAT(message.packets(), SizeIs(2));
+      }));
+
+  std::vector<rtcp::CongestionControlFeedback::PacketInfo> packets = {
+      {.ssrc = 1,
+       .sequence_number = 321,
+       .arrival_time_offset = TimeDelta::Millis(15)},
+      {.ssrc = 1,
+       .sequence_number = 322,
+       .arrival_time_offset = TimeDelta::Millis(17)}};
+  rtcp::CongestionControlFeedback ccfb(std::move(packets), receive_time_ntp);
+  rtcp_transceiver.ReceivePacket(ccfb.Build(), receive_time);
+}
+
 TEST_F(RtcpTransceiverImplTest, ParsesRemb) {
   MockNetworkLinkRtcpObserver link_observer;
   RtcpTransceiverConfig config = DefaultTestConfig();