From 7d5418233d794cc42e64ac44b1fd388a45e811de Mon Sep 17 00:00:00 2001
From: Danil Chapovalov <danilchap@webrtc.org>
Date: Thu, 17 Jun 2021 15:27:12 +0200
Subject: [PATCH] Avoid assembling complicated but unused video rtp header
 extensions

Bug: chromium:1219407
Change-Id: I017de10813a1e80f4af0ba55d8d1aa73077dd131
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/222615
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34326}
---
 modules/rtp_rtcp/source/rtp_packet.h          | 10 +++++++
 .../rtp_rtcp/source/rtp_packet_unittest.cc    | 29 +++++++++++++++++++
 modules/rtp_rtcp/source/rtp_sender_video.cc   |  9 ++++--
 3 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/modules/rtp_rtcp/source/rtp_packet.h b/modules/rtp_rtcp/source/rtp_packet.h
index 1c31f92ce9..81ca02c851 100644
--- a/modules/rtp_rtcp/source/rtp_packet.h
+++ b/modules/rtp_rtcp/source/rtp_packet.h
@@ -114,6 +114,11 @@ class RtpPacket {
   bool HasExtension() const;
   bool HasExtension(ExtensionType type) const;
 
+  // Returns whether there is an associated id for the extension and thus it is
+  // possible to set the extension.
+  template <typename Extension>
+  bool IsRegistered() const;
+
   template <typename Extension, typename FirstValue, typename... Values>
   bool GetExtension(FirstValue, Values...) const;
 
@@ -207,6 +212,11 @@ bool RtpPacket::HasExtension() const {
   return HasExtension(Extension::kId);
 }
 
+template <typename Extension>
+bool RtpPacket::IsRegistered() const {
+  return extensions_.IsRegistered(Extension::kId);
+}
+
 template <typename Extension, typename FirstValue, typename... Values>
 bool RtpPacket::GetExtension(FirstValue first, Values... values) const {
   auto raw = FindExtension(Extension::kId);
diff --git a/modules/rtp_rtcp/source/rtp_packet_unittest.cc b/modules/rtp_rtcp/source/rtp_packet_unittest.cc
index f7f21af41d..533e509d33 100644
--- a/modules/rtp_rtcp/source/rtp_packet_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_packet_unittest.cc
@@ -354,6 +354,35 @@ TEST(RtpPacketTest, CreateWithMaxSizeHeaderExtension) {
   EXPECT_EQ(read, kValue);
 }
 
+TEST(RtpPacketTest, SetsRegisteredExtension) {
+  RtpPacketToSend::ExtensionManager extensions;
+  extensions.Register<TransmissionOffset>(kTransmissionOffsetExtensionId);
+  RtpPacketToSend packet(&extensions);
+
+  EXPECT_TRUE(packet.IsRegistered<TransmissionOffset>());
+  EXPECT_FALSE(packet.HasExtension<TransmissionOffset>());
+
+  // Try to set the extensions.
+  EXPECT_TRUE(packet.SetExtension<TransmissionOffset>(kTimeOffset));
+
+  EXPECT_TRUE(packet.HasExtension<TransmissionOffset>());
+  EXPECT_EQ(packet.GetExtension<TransmissionOffset>(), kTimeOffset);
+}
+
+TEST(RtpPacketTest, FailsToSetUnregisteredExtension) {
+  RtpPacketToSend::ExtensionManager extensions;
+  extensions.Register<TransmissionOffset>(kTransmissionOffsetExtensionId);
+  RtpPacketToSend packet(&extensions);
+
+  EXPECT_FALSE(packet.IsRegistered<TransportSequenceNumber>());
+  EXPECT_FALSE(packet.HasExtension<TransportSequenceNumber>());
+
+  EXPECT_FALSE(packet.SetExtension<TransportSequenceNumber>(42));
+
+  EXPECT_FALSE(packet.HasExtension<TransportSequenceNumber>());
+  EXPECT_EQ(packet.GetExtension<TransportSequenceNumber>(), absl::nullopt);
+}
+
 TEST(RtpPacketTest, SetReservedExtensionsAfterPayload) {
   const size_t kPayloadSize = 4;
   RtpPacketToSend::ExtensionManager extensions;
diff --git a/modules/rtp_rtcp/source/rtp_sender_video.cc b/modules/rtp_rtcp/source/rtp_sender_video.cc
index d344695fdf..4919e3ebf4 100644
--- a/modules/rtp_rtcp/source/rtp_sender_video.cc
+++ b/modules/rtp_rtcp/source/rtp_sender_video.cc
@@ -361,7 +361,8 @@ void RTPSenderVideo::AddRtpHeaderExtensions(
 
   if (video_header.generic) {
     bool extension_is_set = false;
-    if (video_structure_ != nullptr) {
+    if (packet->IsRegistered<RtpDependencyDescriptorExtension>() &&
+        video_structure_ != nullptr) {
       DependencyDescriptor descriptor;
       descriptor.first_packet_in_frame = first_packet;
       descriptor.last_packet_in_frame = last_packet;
@@ -407,7 +408,8 @@ void RTPSenderVideo::AddRtpHeaderExtensions(
     }
 
     // Do not use generic frame descriptor when dependency descriptor is stored.
-    if (!extension_is_set) {
+    if (packet->IsRegistered<RtpGenericFrameDescriptorExtension00>() &&
+        !extension_is_set) {
       RtpGenericFrameDescriptor generic_descriptor;
       generic_descriptor.SetFirstPacketInSubFrame(first_packet);
       generic_descriptor.SetLastPacketInSubFrame(last_packet);
@@ -437,7 +439,8 @@ void RTPSenderVideo::AddRtpHeaderExtensions(
     }
   }
 
-  if (first_packet &&
+  if (packet->IsRegistered<RtpVideoLayersAllocationExtension>() &&
+      first_packet &&
       send_allocation_ != SendVideoLayersAllocation::kDontSend &&
       (video_header.frame_type == VideoFrameType::kVideoFrameKey ||
        PacketWillLikelyBeRequestedForRestransmitionIfLost(video_header))) {