Reland of Only compare sequence numbers from the same SSRC in ForwardErrorCorrection.

webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/modules/rtp_rtcp/source/ulpfec_receiver_impl.h"
 
 #include <memory>
 #include <utility>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h"
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
 
-UlpfecReceiver* UlpfecReceiver::Create(RecoveredPacketReceiver* callback) {
-  return new UlpfecReceiverImpl(callback);
+UlpfecReceiver* UlpfecReceiver::Create(uint32_t ssrc,
+                                       RecoveredPacketReceiver* callback) {
+  return new UlpfecReceiverImpl(ssrc, callback);
 }
 
-UlpfecReceiverImpl::UlpfecReceiverImpl(RecoveredPacketReceiver* callback)
-    : recovered_packet_callback_(callback),
-      fec_(ForwardErrorCorrection::CreateUlpfec()) {}
+UlpfecReceiverImpl::UlpfecReceiverImpl(uint32_t ssrc,
+                                       RecoveredPacketReceiver* callback)
+    : ssrc_(ssrc),
+      recovered_packet_callback_(callback),
+      fec_(ForwardErrorCorrection::CreateUlpfec(ssrc_)) {}
 
 UlpfecReceiverImpl::~UlpfecReceiverImpl() {
   received_packets_.clear();
   fec_->ResetState(&recovered_packets_);
 }
 
 FecPacketCounter UlpfecReceiverImpl::GetPacketCounter() const {
   rtc::CritScope cs(&crit_sect_);
   return packet_counter_;
 }
@@ skipping 24 matching lines @@
 //        block is the redundancy.
 //
 //    block length:  10 bits Length in bytes of the corresponding data
 //        block excluding header.
 
 int32_t UlpfecReceiverImpl::AddReceivedRedPacket(
     const RTPHeader& header,
     const uint8_t* incoming_rtp_packet,
     size_t packet_length,
     uint8_t ulpfec_payload_type) {
+  if (header.ssrc != ssrc_) {
+    LOG(LS_INFO)

[holmer, 2017/06/28 13:53:06]

Should this be a warning?

[brandtr_google, 2017/06/28 14:01:56]

I was thinking that could be a bit spammy. If we receive one of these packets,
we might receive several.

[holmer, 2017/06/29 10:50:11]

But we don't expect to ever do that, right? I'd want to know if my sender sends
broken packets.

You could throttle them if you are worried about frequency.

[brandtr, 2017/06/30 08:24:40]

Right, this should never happen. Updating the logging severity in
https://codereview.webrtc.org/2965533003/.

+        << "Received RED packet with different SSRC than expected; dropping.";
+    return -1;
+  }
+
   rtc::CritScope cs(&crit_sect_);
 
   uint8_t red_header_length = 1;
   size_t payload_data_length = packet_length - header.headerLength;
 
   if (payload_data_length == 0) {
     LOG(LS_WARNING) << "Corrupt/truncated FEC packet.";
     return -1;
   }
 
   // Remove RED header of incoming packet and store as a virtual RTP packet.
   std::unique_ptr<ForwardErrorCorrection::ReceivedPacket> received_packet(
       new ForwardErrorCorrection::ReceivedPacket());
   received_packet->pkt = new ForwardErrorCorrection::Packet();
 
   // Get payload type from RED header and sequence number from RTP header.
   uint8_t payload_type = incoming_rtp_packet[header.headerLength] & 0x7f;
   received_packet->is_fec = payload_type == ulpfec_payload_type;
+  received_packet->ssrc = header.ssrc;
   received_packet->seq_num = header.sequenceNumber;
 
   uint16_t block_length = 0;
   if (incoming_rtp_packet[header.headerLength] & 0x80) {
     // f bit set in RED header, i.e. there are more than one RED header blocks.
     red_header_length = 4;
     if (payload_data_length < red_header_length + 1u) {
       LOG(LS_WARNING) << "Corrupt/truncated FEC packet.";
       return -1;
     }
@@ skipping 45 matching lines @@
     // Copy payload data.
     memcpy(received_packet->pkt->data + header.headerLength,
            incoming_rtp_packet + header.headerLength + red_header_length,
            block_length);
     received_packet->pkt->length = block_length;
 
     second_received_packet.reset(new ForwardErrorCorrection::ReceivedPacket);
     second_received_packet->pkt = new ForwardErrorCorrection::Packet;
 
     second_received_packet->is_fec = true;
+    second_received_packet->ssrc = header.ssrc;
     second_received_packet->seq_num = header.sequenceNumber;
     ++packet_counter_.num_fec_packets;
 
     // Copy FEC payload data.
     memcpy(second_received_packet->pkt->data,
            incoming_rtp_packet + header.headerLength + red_header_length +
                block_length,
            payload_data_length - red_header_length - block_length);
 
     second_received_packet->pkt->length =
@@ skipping 66 matching lines @@
     recovered_packet_callback_->OnRecoveredPacket(packet->data,
                                                   packet->length);
     crit_sect_.Enter();
     recovered_packet->returned = true;
   }
   crit_sect_.Leave();
   return 0;
 }
 
 }  // namespace webrtc