Reland of Create RtcpDemuxer

webrtc/call/rtcp_demuxer.h

Index: webrtc/call/rtcp_demuxer.h
diff --git a/webrtc/call/rtcp_demuxer.h b/webrtc/call/rtcp_demuxer.h
new file mode 100644
index 0000000000000000000000000000000000000000..c5c1621036b9efff731b1ac6a1370b32098284b0
--- /dev/null
+++ b/webrtc/call/rtcp_demuxer.h
@@ -0,0 +1,85 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_CALL_RTCP_DEMUXER_H_
+#define WEBRTC_CALL_RTCP_DEMUXER_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "webrtc/base/array_view.h"
+#include "webrtc/base/basictypes.h"
+#include "webrtc/call/rsid_resolution_observer.h"
+
+namespace webrtc {
+
+class RtcpPacketSinkInterface;
+
+// This class represents the RTCP demuxing, for a single RTP session (i.e., one
+// SSRC space, see RFC 7656). It isn't thread aware, leaving responsibility of
+// multithreading issues to the user of this class.
+class RtcpDemuxer : public RsidResolutionObserver {
+ public:
+  RtcpDemuxer();
+  ~RtcpDemuxer() override;
+
+  // Registers a sink. The sink will be notified of incoming RTCP packets with
+  // that sender-SSRC. The same sink can be registered for multiple SSRCs, and
+  // the same SSRC can have multiple sinks. Null pointer is not allowed.
+  // Sinks may be associated with both an SSRC and an RSID.
+  // Sinks may be registered as SSRC/RSID-specific or broadcast, but not both.
+  void AddSink(uint32_t sender_ssrc, RtcpPacketSinkInterface* sink);
+
+  // Registers a sink. Once the RSID is resolved to an SSRC, the sink will be
+  // notified of all RTCP packets with that sender-SSRC.
+  // The same sink can be registered for multiple RSIDs, and
+  // the same RSID can have multiple sinks. Null pointer is not allowed.
+  // Sinks may be associated with both an SSRC and an RSID.
+  // Sinks may be registered as SSRC/RSID-specific or broadcast, but not both.
+  void AddSink(const std::string& rsid, RtcpPacketSinkInterface* sink);
+
+  // Registers a sink. The sink will be notified of any incoming RTCP packet.
+  // Null pointer is not allowed.
+  // Sinks may be registered as SSRC/RSID-specific or broadcast, but not both.
+  void AddBroadcastSink(RtcpPacketSinkInterface* sink);
+
+  // Undo previous AddSink() calls with the given sink.
+  void RemoveSink(const RtcpPacketSinkInterface* sink);
+
+  // Undo AddBroadcastSink().
+  void RemoveBroadcastSink(const RtcpPacketSinkInterface* sink);
+
+  // Process a new RTCP packet and forward it to the appropriate sinks.
+  void OnRtcpPacket(rtc::ArrayView<const uint8_t> packet);
+
+  // Implement RsidResolutionObserver - become notified whenever RSIDs resolve
+  // to an SSRC.
+  void OnRsidResolved(const std::string& rsid, uint32_t ssrc) override;
+
+  // TODO(eladalon): Add the ability to resolve RSIDs and inform observers,
+  // like in the RtpDemuxer case, once the relevant standard is finalized.
+
+ private:
+  // Records the association SSRCs to sinks.
+  std::multimap<uint32_t, RtcpPacketSinkInterface*> ssrc_sinks_;
+
+  // Records the association RSIDs to sinks.
+  std::multimap<std::string, RtcpPacketSinkInterface*> rsid_sinks_;
+
+  // Sinks which will receive notifications of all incoming RTCP packets.
+  // Additional/removal of sinks is expected to be significantly less frequent
+  // than RTCP message reception; container chosen for iteration performance.
+  std::vector<RtcpPacketSinkInterface*> broadcast_sinks_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_CALL_RTCP_DEMUXER_H_