Reland of Create RtcpDemuxer

webrtc/call/rtcp_demuxer.cc

Index: webrtc/call/rtcp_demuxer.cc
diff --git a/webrtc/call/rtcp_demuxer.cc b/webrtc/call/rtcp_demuxer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6054fc0541b3f9fae3a25b13008d53cc9ae75712
--- /dev/null
+++ b/webrtc/call/rtcp_demuxer.cc
@@ -0,0 +1,100 @@
+/*
+ *  Copyright (c) 2017 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/call/rtcp_demuxer.h"
+
+#include "webrtc/base/checks.h"
+#include "webrtc/call/rtcp_packet_sink_interface.h"
+#include "webrtc/call/rtp_rtcp_demuxer_helper.h"
+#include "webrtc/common_types.h"
+
+namespace webrtc {
+
+RtcpDemuxer::RtcpDemuxer() = default;
+
+RtcpDemuxer::~RtcpDemuxer() {
+  RTC_DCHECK(ssrc_sinks_.empty());
+  RTC_DCHECK(rsid_sinks_.empty());
+  RTC_DCHECK(broadcast_sinks_.empty());
+}
+
+void RtcpDemuxer::AddSink(uint32_t sender_ssrc, RtcpPacketSinkInterface* sink) {
+  RTC_DCHECK(sink);
+  RTC_DCHECK(!ContainerHasKey(broadcast_sinks_, sink));
+  RTC_DCHECK(!MultimapAssociationExists(ssrc_sinks_, sender_ssrc, sink));
+  ssrc_sinks_.emplace(sender_ssrc, sink);
+}
+
+void RtcpDemuxer::AddSink(const std::string& rsid,
+                          RtcpPacketSinkInterface* sink) {
+  RTC_DCHECK(StreamId::IsLegalName(rsid));
+  RTC_DCHECK(sink);
+  RTC_DCHECK(!ContainerHasKey(broadcast_sinks_, sink));
+  RTC_DCHECK(!MultimapAssociationExists(rsid_sinks_, rsid, sink));
+  rsid_sinks_.emplace(rsid, sink);
+}
+
+void RtcpDemuxer::AddBroadcastSink(RtcpPacketSinkInterface* sink) {
+  RTC_DCHECK(sink);
+  RTC_DCHECK(!MultimapHasValue(ssrc_sinks_, sink));
+  RTC_DCHECK(!MultimapHasValue(rsid_sinks_, sink));
+  RTC_DCHECK(!ContainerHasKey(broadcast_sinks_, sink));
+  broadcast_sinks_.push_back(sink);
+}
+
+void RtcpDemuxer::RemoveSink(const RtcpPacketSinkInterface* sink) {
+  RTC_DCHECK(sink);
+  size_t removal_count = RemoveFromMultimapByValue(&ssrc_sinks_, sink) +
+                         RemoveFromMultimapByValue(&rsid_sinks_, sink);
+  RTC_DCHECK_GT(removal_count, 0);
+}
+
+void RtcpDemuxer::RemoveBroadcastSink(const RtcpPacketSinkInterface* sink) {
+  RTC_DCHECK(sink);
+  auto it = std::find(broadcast_sinks_.begin(), broadcast_sinks_.end(), sink);
+  RTC_DCHECK(it != broadcast_sinks_.end());
+  broadcast_sinks_.erase(it);
+}
+
+void RtcpDemuxer::OnRtcpPacket(rtc::ArrayView<const uint8_t> packet) {
+  // Perform sender-SSRC-based demuxing for packets with a sender-SSRC.
+  rtc::Optional<uint32_t> sender_ssrc = ParseRtcpPacketSenderSsrc(packet);
+  if (sender_ssrc) {
+    auto it_range = ssrc_sinks_.equal_range(*sender_ssrc);
+    for (auto it = it_range.first; it != it_range.second; ++it) {
+      it->second->OnRtcpPacket(packet);
+    }
+  }
+
+  // All packets, even those without a sender-SSRC, are broadcast to sinks
+  // which listen to broadcasts.
+  for (RtcpPacketSinkInterface* sink : broadcast_sinks_) {
+    sink->OnRtcpPacket(packet);
+  }
+}
+
+void RtcpDemuxer::OnRsidResolved(const std::string& rsid, uint32_t ssrc) {
+  // Record the new SSRC association for all of the sinks that were associated
+  // with the RSID.
+  auto it_range = rsid_sinks_.equal_range(rsid);
+  for (auto it = it_range.first; it != it_range.second; ++it) {
+    RtcpPacketSinkInterface* sink = it->second;
+    // Watch out for pre-existing SSRC-based associations.
+    if (!MultimapAssociationExists(ssrc_sinks_, ssrc, sink)) {
+      AddSink(ssrc, sink);
+    }
+  }
+
+  // RSIDs are uniquely associated with SSRCs; no need to keep in memory
+  // the RSID-to-sink association of resolved RSIDs.
+  rsid_sinks_.erase(it_range.first, it_range.second);
+}
+
+}  // namespace webrtc