Reland of: Separating SCTP code from BaseChannel/MediaChannel.

webrtc/media/sctp/sctptransport.h

Index: webrtc/media/sctp/sctptransport.h
diff --git a/webrtc/media/sctp/sctptransport.h b/webrtc/media/sctp/sctptransport.h
new file mode 100644
index 0000000000000000000000000000000000000000..a5ae717cac48ef3d26c0104ccf0e471e689b3dd3
--- /dev/null
+++ b/webrtc/media/sctp/sctptransport.h
@@ -0,0 +1,195 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MEDIA_SCTP_SCTPTRANSPORT_H_
+#define WEBRTC_MEDIA_SCTP_SCTPTRANSPORT_H_
+
+#include <errno.h>
+
+#include <memory>  // for unique_ptr.
+#include <set>
+#include <string>
+#include <vector>
+
+#include "webrtc/base/asyncinvoker.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/base/copyonwritebuffer.h"
+#include "webrtc/base/sigslot.h"
+#include "webrtc/base/thread.h"
+// For SendDataParams/ReceiveDataParams.
+// TODO(deadbeef): Use something else for SCTP. It's confusing that we use an
+// SSRC field for SID.
+#include "webrtc/media/base/mediachannel.h"

[pthatcher1, 2016/12/23 01:39:31]

Just go ahead  and rename it to .sid and make the rtp data channel have the
oddity that a SID turns into an SSRC.  And you can probably move
SendDataParams/ReceiveDataParams out of mediachannel.h.

[Taylor Brandstetter, 2016/12/23 06:29:05]

I changed it to a union type. I'll leave moving the declarations as a TODO (we
should also probably move the sctptransport files out of media/)

+#include "webrtc/media/sctp/sctptransportinternal.h"
+#include "webrtc/p2p/base/transportchannel.h"
+
+// Defined by "usrsctplib/usrsctp.h"
+struct sockaddr_conn;
+struct sctp_assoc_change;
+struct sctp_stream_reset_event;
+// Defined by <sys/socket.h>
+struct socket;
+namespace cricket {
+
+// Holds data to be passed on to a channel.
+struct SctpInboundPacket;
+
+// From channel calls, data flows like this:
+// [network thread (although it can in princple be another thread)]
+//  1.  SctpTransport::SendData(data)
+//  2.  usrsctp_sendv(data)
+// [network thread returns; sctp thread then calls the following]
+//  3.  OnSctpOutboundPacket(wrapped_data)
+// [sctp thread returns having async invoked on the network thread]
+//  4.  SctpTransport::OnPacketFromSctpToNetwork(wrapped_data)
+//  5.  TransportChannel::SendPacket(wrapped_data)
+//  6.  ... across network ... a packet is sent back ...
+//  7.  SctpTransport::OnPacketReceived(wrapped_data)
+//  8.  usrsctp_conninput(wrapped_data)
+// [network thread returns; sctp thread then calls the following]
+//  9.  OnSctpInboundData(data)
+// [sctp thread returns having async invoked on the network thread]
+//  10. SctpTransport::OnInboundPacketFromSctpToChannel(inboundpacket)
+//  11. SctpTransport::OnDataFromSctpToChannel(data)
+//  12. SctpTransport::SignalDataReceived(data)
+// [from the same thread, methods registered/connected to
+//  SctpTransport are called with the recieved data]
+class SctpTransport : public SctpTransportInternal,
+                      public sigslot::has_slots<> {
+ public:
+  // |network_thread| is where packets will be processed and callbacks from
+  // this transport will be posted, and is the only thread on which public
+  // methods can be called.
+  // |channel| is required (must not be null).
+  SctpTransport(rtc::Thread* network_thread,
+                cricket::TransportChannel* channel);
+  ~SctpTransport() override;
+
+  // SctpTransportInternal overrides (see sctptransportinternal.h for comments).
+  void SetTransportChannel(cricket::TransportChannel* channel) override;
+  bool Start(int local_port, int remote_port) override;
+  bool OpenStream(int sid) override;
+  bool ResetStream(int sid) override;
+  bool SendData(const SendDataParams& params,
+                const rtc::CopyOnWriteBuffer& payload,
+                SendDataResult* result = nullptr) override;
+  bool ReadyToSendData() override;
+  void set_debug_name_for_testing(const char* debug_name) override {
+    debug_name_ = debug_name;
+  }
+
+  // Exposed to allow Post call from c-callbacks.
+  // TODO(deadbeef): Remove this or at least make it return a const pointer.
+  rtc::Thread* network_thread() const { return network_thread_; }
+
+ private:
+  void ConnectTransportChannelSignals();
+  void DisconnectTransportChannelSignals();
+
+  // Creates the socket and connects.
+  bool Connect();
+
+  // Returns false when opening the socket failed.
+  bool OpenSctpSocket();
+  // Helpet method to set socket options.
+  bool ConfigureSctpSocket();
+  // Sets |sock_ |to nullptr.
+  void CloseSctpSocket();
+
+  // Sends a SCTP_RESET_STREAM for all streams in closing_ssids_.
+  bool SendQueuedStreamResets();
+
+  // Sets the "ready to send" flag and fires signal if needed.
+  void SetReadyToSendData();
+
+  // Callbacks from DTLS channel.
+  void OnWritableState(rtc::PacketTransportInterface* transport);
+  virtual void OnPacketRead(rtc::PacketTransportInterface* transport,
+                            const char* data,
+                            size_t len,
+                            const rtc::PacketTime& packet_time,
+                            int flags);
+
+  // Methods related to usrsctp callbacks.
+  void OnSendThresholdCallback();
+  sockaddr_conn GetSctpSockAddr(int port);
+
+  // Called using |invoker_| to send packet on the network.
+  void OnPacketFromSctpToNetwork(const rtc::CopyOnWriteBuffer& buffer);
+  // Called using |invoker_| to decide what to do with the packet.
+  // The |flags| parameter is used by SCTP to distinguish notification packets
+  // from other types of packets.
+  void OnInboundPacketFromSctpToChannel(const rtc::CopyOnWriteBuffer& buffer,
+                                        ReceiveDataParams params,
+                                        int flags);
+  void OnDataFromSctpToChannel(const ReceiveDataParams& params,
+                               const rtc::CopyOnWriteBuffer& buffer);
+  void OnNotificationFromSctp(const rtc::CopyOnWriteBuffer& buffer);
+  void OnNotificationAssocChange(const sctp_assoc_change& change);
+
+  void OnStreamResetEvent(const struct sctp_stream_reset_event* evt);
+
+  // Responsible for marshalling incoming data to the channels listeners, and
+  // outgoing data to the network interface.
+  rtc::Thread* network_thread_;
+  // Helps pass inbound/outbound packets asynchronously to the network thread.
+  rtc::AsyncInvoker invoker_;
+  // Underlying DTLS channel.
+  TransportChannel* transport_channel_;
+  bool was_ever_writable_ = false;
+  int local_port_ = kSctpDefaultPort;
+  int remote_port_ = kSctpDefaultPort;
+  struct socket* sock_ = nullptr;  // The socket created by usrsctp_socket(...).
+
+  // Has Start been called? Don't create SCTP socket until it has.
+  bool started_ = false;
+  // Are we ready to queue data (SCTP socket created, and not blocked due to
+  // congestion control)? Different than |transport_channel_|'s "ready to
+  // send".
+  bool ready_to_send_data_ = false;
+
+  typedef std::set<uint32_t> StreamSet;
+  // When a data channel opens a stream, it goes into open_streams_.  When we
+  // want to close it, the stream's ID goes into queued_reset_streams_.  When
+  // we actually transmit a RE-CONFIG chunk with that stream ID, the ID goes
+  // into sent_reset_streams_.  When we get a response RE-CONFIG chunk back
+  // acknowledging the reset, we remove the stream ID from
+  // sent_reset_streams_.  We use sent_reset_streams_ to differentiate
+  // between acknowledgment RE-CONFIG and peer-initiated RE-CONFIGs.
+  StreamSet open_streams_;
+  StreamSet queued_reset_streams_;
+  StreamSet sent_reset_streams_;
+
+  // A static human-readable name for debugging messages.
+  const char* debug_name_ = "SctpTransport";
+  // Hides usrsctp interactions from this header file.
+  class UsrSctpWrapper;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(SctpTransport);
+};
+
+class SctpTransportFactory : public SctpTransportInternalFactory {
+ public:
+  explicit SctpTransportFactory(rtc::Thread* network_thread)
+      : network_thread_(network_thread) {}
+
+  std::unique_ptr<SctpTransportInternal> CreateSctpTransport(
+      TransportChannel* channel) override {
+    return std::unique_ptr<SctpTransportInternal>(
+        new SctpTransport(network_thread_, channel));
+  }
+
+ private:
+  rtc::Thread* network_thread_;
+};
+
+}  // namespace cricket
+
+#endif  // WEBRTC_MEDIA_SCTP_SCTPTRANSPORT_H_