Revert of Separating SCTP code from BaseChannel/MediaChannel.

webrtc/media/sctp/sctptransport.cc

Index: webrtc/media/sctp/sctptransport.cc
diff --git a/webrtc/media/sctp/sctptransport.cc b/webrtc/media/sctp/sctptransport.cc
deleted file mode 100644
index b95cf8a4baf444bc3f14aee79e47e9a9e2983d0a..0000000000000000000000000000000000000000
--- a/webrtc/media/sctp/sctptransport.cc
+++ /dev/null
@@ -1,1090 +0,0 @@
-/*
- *  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 <errno.h>
-namespace {
-// Some ERRNO values get re-#defined to WSA* equivalents in some talk/
-// headers. We save the original ones in an enum.
-enum PreservedErrno {
-  SCTP_EINPROGRESS = EINPROGRESS,
-  SCTP_EWOULDBLOCK = EWOULDBLOCK
-};
-}
-
-#include "webrtc/media/sctp/sctptransport.h"
-
-#include <stdarg.h>
-#include <stdio.h>
-
-#include <memory>
-#include <sstream>
-
-#include "usrsctplib/usrsctp.h"
-#include "webrtc/base/arraysize.h"
-#include "webrtc/base/copyonwritebuffer.h"
-#include "webrtc/base/criticalsection.h"
-#include "webrtc/base/helpers.h"
-#include "webrtc/base/logging.h"
-#include "webrtc/base/safe_conversions.h"
-#include "webrtc/base/thread_checker.h"
-#include "webrtc/base/trace_event.h"
-#include "webrtc/media/base/codec.h"
-#include "webrtc/media/base/mediaconstants.h"
-#include "webrtc/media/base/rtputils.h"  // For IsRtpPacket
-#include "webrtc/media/base/streamparams.h"
-
-namespace {
-
-// The biggest SCTP packet. Starting from a 'safe' wire MTU value of 1280,
-// take off 80 bytes for DTLS/TURN/TCP/IP overhead.
-static constexpr size_t kSctpMtu = 1200;
-
-// The size of the SCTP association send buffer.  256kB, the usrsctp default.
-static constexpr int kSendBufferSize = 262144;
-
-// Set the initial value of the static SCTP Data Engines reference count.
-int g_usrsctp_usage_count = 0;
-rtc::GlobalLockPod g_usrsctp_lock_;
-
-// DataMessageType is used for the SCTP "Payload Protocol Identifier", as
-// defined in http://tools.ietf.org/html/rfc4960#section-14.4
-//
-// For the list of IANA approved values see:
-// http://www.iana.org/assignments/sctp-parameters/sctp-parameters.xml
-// The value is not used by SCTP itself. It indicates the protocol running
-// on top of SCTP.
-enum PayloadProtocolIdentifier {
-  PPID_NONE = 0,  // No protocol is specified.
-  // Matches the PPIDs in mozilla source and
-  // https://datatracker.ietf.org/doc/draft-ietf-rtcweb-data-protocol Sec. 9
-  // They're not yet assigned by IANA.
-  PPID_CONTROL = 50,
-  PPID_BINARY_PARTIAL = 52,
-  PPID_BINARY_LAST = 53,
-  PPID_TEXT_PARTIAL = 54,
-  PPID_TEXT_LAST = 51
-};
-
-typedef std::set<uint32_t> StreamSet;
-
-// Returns a comma-separated, human-readable list of the stream IDs in 's'
-std::string ListStreams(const StreamSet& s) {
-  std::stringstream result;
-  bool first = true;
-  for (StreamSet::const_iterator it = s.begin(); it != s.end(); ++it) {
-    if (!first) {
-      result << ", " << *it;
-    } else {
-      result << *it;
-      first = false;
-    }
-  }
-  return result.str();
-}
-
-// Returns a pipe-separated, human-readable list of the SCTP_STREAM_RESET
-// flags in 'flags'
-std::string ListFlags(int flags) {
-  std::stringstream result;
-  bool first = true;
-// Skip past the first 12 chars (strlen("SCTP_STREAM_"))
-#define MAKEFLAG(X) \
-  { X, #X + 12 }
-  struct flaginfo_t {
-    int value;
-    const char* name;
-  } flaginfo[] = {MAKEFLAG(SCTP_STREAM_RESET_INCOMING_SSN),
-                  MAKEFLAG(SCTP_STREAM_RESET_OUTGOING_SSN),
-                  MAKEFLAG(SCTP_STREAM_RESET_DENIED),
-                  MAKEFLAG(SCTP_STREAM_RESET_FAILED),
-                  MAKEFLAG(SCTP_STREAM_CHANGE_DENIED)};
-#undef MAKEFLAG
-  for (uint32_t i = 0; i < arraysize(flaginfo); ++i) {
-    if (flags & flaginfo[i].value) {
-      if (!first)
-        result << " | ";
-      result << flaginfo[i].name;
-      first = false;
-    }
-  }
-  return result.str();
-}
-
-// Returns a comma-separated, human-readable list of the integers in 'array'.
-// All 'num_elems' of them.
-std::string ListArray(const uint16_t* array, int num_elems) {
-  std::stringstream result;
-  for (int i = 0; i < num_elems; ++i) {
-    if (i) {
-      result << ", " << array[i];
-    } else {
-      result << array[i];
-    }
-  }
-  return result.str();
-}
-
-// Helper for logging SCTP messages.
-void DebugSctpPrintf(const char* format, ...) {
-#if RTC_DCHECK_IS_ON
-  char s[255];
-  va_list ap;
-  va_start(ap, format);
-  vsnprintf(s, sizeof(s), format, ap);
-  LOG(LS_INFO) << "SCTP: " << s;
-  va_end(ap);
-#endif
-}
-
-// Get the PPID to use for the terminating fragment of this type.
-PayloadProtocolIdentifier GetPpid(cricket::DataMessageType type) {
-  switch (type) {
-    default:
-    case cricket::DMT_NONE:
-      return PPID_NONE;
-    case cricket::DMT_CONTROL:
-      return PPID_CONTROL;
-    case cricket::DMT_BINARY:
-      return PPID_BINARY_LAST;
-    case cricket::DMT_TEXT:
-      return PPID_TEXT_LAST;
-  }
-}
-
-bool GetDataMediaType(PayloadProtocolIdentifier ppid,
-                      cricket::DataMessageType* dest) {
-  RTC_DCHECK(dest != NULL);
-  switch (ppid) {
-    case PPID_BINARY_PARTIAL:
-    case PPID_BINARY_LAST:
-      *dest = cricket::DMT_BINARY;
-      return true;
-
-    case PPID_TEXT_PARTIAL:
-    case PPID_TEXT_LAST:
-      *dest = cricket::DMT_TEXT;
-      return true;
-
-    case PPID_CONTROL:
-      *dest = cricket::DMT_CONTROL;
-      return true;
-
-    case PPID_NONE:
-      *dest = cricket::DMT_NONE;
-      return true;
-
-    default:
-      return false;
-  }
-}
-
-// Log the packet in text2pcap format, if log level is at LS_VERBOSE.
-void VerboseLogPacket(const void* data, size_t length, int direction) {
-  if (LOG_CHECK_LEVEL(LS_VERBOSE) && length > 0) {
-    char* dump_buf;
-    // Some downstream project uses an older version of usrsctp that expects
-    // a non-const "void*" as first parameter when dumping the packet, so we
-    // need to cast the const away here to avoid a compiler error.
-    if ((dump_buf = usrsctp_dumppacket(const_cast<void*>(data), length,
-                                       direction)) != NULL) {
-      LOG(LS_VERBOSE) << dump_buf;
-      usrsctp_freedumpbuffer(dump_buf);
-    }
-  }
-}
-
-}  // namespace
-
-namespace cricket {
-
-// Handles global init/deinit, and mapping from usrsctp callbacks to
-// SctpTransport calls.
-class SctpTransport::UsrSctpWrapper {
- public:
-  static void InitializeUsrSctp() {
-    LOG(LS_INFO) << __FUNCTION__;
-    // First argument is udp_encapsulation_port, which is not releveant for our
-    // AF_CONN use of sctp.
-    usrsctp_init(0, &UsrSctpWrapper::OnSctpOutboundPacket, &DebugSctpPrintf);
-
-    // To turn on/off detailed SCTP debugging. You will also need to have the
-    // SCTP_DEBUG cpp defines flag.
-    // usrsctp_sysctl_set_sctp_debug_on(SCTP_DEBUG_ALL);
-
-    // TODO(ldixon): Consider turning this on/off.
-    usrsctp_sysctl_set_sctp_ecn_enable(0);
-
-    // This is harmless, but we should find out when the library default
-    // changes.
-    int send_size = usrsctp_sysctl_get_sctp_sendspace();
-    if (send_size != kSendBufferSize) {
-      LOG(LS_ERROR) << "Got different send size than expected: " << send_size;
-    }
-
-    // TODO(ldixon): Consider turning this on/off.
-    // This is not needed right now (we don't do dynamic address changes):
-    // If SCTP Auto-ASCONF is enabled, the peer is informed automatically
-    // when a new address is added or removed. This feature is enabled by
-    // default.
-    // usrsctp_sysctl_set_sctp_auto_asconf(0);
-
-    // TODO(ldixon): Consider turning this on/off.
-    // Add a blackhole sysctl. Setting it to 1 results in no ABORTs
-    // being sent in response to INITs, setting it to 2 results
-    // in no ABORTs being sent for received OOTB packets.
-    // This is similar to the TCP sysctl.
-    //
-    // See: http://lakerest.net/pipermail/sctp-coders/2012-January/009438.html
-    // See: http://svnweb.freebsd.org/base?view=revision&revision=229805
-    // usrsctp_sysctl_set_sctp_blackhole(2);
-
-    // Set the number of default outgoing streams. This is the number we'll
-    // send in the SCTP INIT message.
-    usrsctp_sysctl_set_sctp_nr_outgoing_streams_default(kMaxSctpStreams);
-  }
-
-  static void UninitializeUsrSctp() {
-    LOG(LS_INFO) << __FUNCTION__;
-    // usrsctp_finish() may fail if it's called too soon after the transports
-    // are
-    // closed. Wait and try again until it succeeds for up to 3 seconds.
-    for (size_t i = 0; i < 300; ++i) {
-      if (usrsctp_finish() == 0) {
-        return;
-      }
-
-      rtc::Thread::SleepMs(10);
-    }
-    LOG(LS_ERROR) << "Failed to shutdown usrsctp.";
-  }
-
-  static void IncrementUsrSctpUsageCount() {
-    rtc::GlobalLockScope lock(&g_usrsctp_lock_);
-    if (!g_usrsctp_usage_count) {
-      InitializeUsrSctp();
-    }
-    ++g_usrsctp_usage_count;
-  }
-
-  static void DecrementUsrSctpUsageCount() {
-    rtc::GlobalLockScope lock(&g_usrsctp_lock_);
-    --g_usrsctp_usage_count;
-    if (!g_usrsctp_usage_count) {
-      UninitializeUsrSctp();
-    }
-  }
-
-  // This is the callback usrsctp uses when there's data to send on the network
-  // that has been wrapped appropriatly for the SCTP protocol.
-  static int OnSctpOutboundPacket(void* addr,
-                                  void* data,
-                                  size_t length,
-                                  uint8_t tos,
-                                  uint8_t set_df) {
-    SctpTransport* transport = static_cast<SctpTransport*>(addr);
-    LOG(LS_VERBOSE) << "global OnSctpOutboundPacket():"
-                    << "addr: " << addr << "; length: " << length
-                    << "; tos: " << std::hex << static_cast<int>(tos)
-                    << "; set_df: " << std::hex << static_cast<int>(set_df);
-
-    VerboseLogPacket(data, length, SCTP_DUMP_OUTBOUND);
-    // Note: We have to copy the data; the caller will delete it.
-    rtc::CopyOnWriteBuffer buf(reinterpret_cast<uint8_t*>(data), length);
-    // TODO(deadbeef): Why do we need an AsyncInvoke here? We're already on the
-    // right thread and don't need to unwind the stack.
-    transport->invoker_.AsyncInvoke<void>(
-        RTC_FROM_HERE, transport->network_thread_,
-        rtc::Bind(&SctpTransport::OnPacketFromSctpToNetwork, transport, buf));
-    return 0;
-  }
-
-  // This is the callback called from usrsctp when data has been received, after
-  // a packet has been interpreted and parsed by usrsctp and found to contain
-  // payload data. It is called by a usrsctp thread. It is assumed this function
-  // will free the memory used by 'data'.
-  static int OnSctpInboundPacket(struct socket* sock,
-                                 union sctp_sockstore addr,
-                                 void* data,
-                                 size_t length,
-                                 struct sctp_rcvinfo rcv,
-                                 int flags,
-                                 void* ulp_info) {
-    SctpTransport* transport = static_cast<SctpTransport*>(ulp_info);
-    // Post data to the transport's receiver thread (copying it).
-    // TODO(ldixon): Unclear if copy is needed as this method is responsible for
-    // memory cleanup. But this does simplify code.
-    const PayloadProtocolIdentifier ppid =
-        static_cast<PayloadProtocolIdentifier>(
-            rtc::HostToNetwork32(rcv.rcv_ppid));
-    DataMessageType type = DMT_NONE;
-    if (!GetDataMediaType(ppid, &type) && !(flags & MSG_NOTIFICATION)) {
-      // It's neither a notification nor a recognized data packet.  Drop it.
-      LOG(LS_ERROR) << "Received an unknown PPID " << ppid
-                    << " on an SCTP packet.  Dropping.";
-    } else {
-      rtc::CopyOnWriteBuffer buffer;
-      ReceiveDataParams params;
-      buffer.SetData(reinterpret_cast<uint8_t*>(data), length);
-      params.sid = rcv.rcv_sid;
-      params.seq_num = rcv.rcv_ssn;
-      params.timestamp = rcv.rcv_tsn;
-      params.type = type;
-      // The ownership of the packet transfers to |invoker_|. Using
-      // CopyOnWriteBuffer is the most convenient way to do this.
-      transport->invoker_.AsyncInvoke<void>(
-          RTC_FROM_HERE, transport->network_thread_,
-          rtc::Bind(&SctpTransport::OnInboundPacketFromSctpToChannel, transport,
-                    buffer, params, flags));
-    }
-    free(data);
-    return 1;
-  }
-
-  static SctpTransport* GetTransportFromSocket(struct socket* sock) {
-    struct sockaddr* addrs = nullptr;
-    int naddrs = usrsctp_getladdrs(sock, 0, &addrs);
-    if (naddrs <= 0 || addrs[0].sa_family != AF_CONN) {
-      return nullptr;
-    }
-    // usrsctp_getladdrs() returns the addresses bound to this socket, which
-    // contains the SctpTransport* as sconn_addr.  Read the pointer,
-    // then free the list of addresses once we have the pointer.  We only open
-    // AF_CONN sockets, and they should all have the sconn_addr set to the
-    // pointer that created them, so [0] is as good as any other.
-    struct sockaddr_conn* sconn =
-        reinterpret_cast<struct sockaddr_conn*>(&addrs[0]);
-    SctpTransport* transport =
-        reinterpret_cast<SctpTransport*>(sconn->sconn_addr);
-    usrsctp_freeladdrs(addrs);
-
-    return transport;
-  }
-
-  static int SendThresholdCallback(struct socket* sock, uint32_t sb_free) {
-    // Fired on our I/O thread. SctpTransport::OnPacketReceived() gets
-    // a packet containing acknowledgments, which goes into usrsctp_conninput,
-    // and then back here.
-    SctpTransport* transport = GetTransportFromSocket(sock);
-    if (!transport) {
-      LOG(LS_ERROR)
-          << "SendThresholdCallback: Failed to get transport for socket "
-          << sock;
-      return 0;
-    }
-    transport->OnSendThresholdCallback();
-    return 0;
-  }
-};
-
-SctpTransport::SctpTransport(rtc::Thread* network_thread,
-                             TransportChannel* channel)
-    : network_thread_(network_thread),
-      transport_channel_(channel),
-      was_ever_writable_(channel->writable()) {
-  RTC_DCHECK(network_thread_);
-  RTC_DCHECK(transport_channel_);
-  RTC_DCHECK_RUN_ON(network_thread_);
-  ConnectTransportChannelSignals();
-}
-
-SctpTransport::~SctpTransport() {
-  // Close abruptly; no reset procedure.
-  CloseSctpSocket();
-}
-
-void SctpTransport::SetTransportChannel(cricket::TransportChannel* channel) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  RTC_DCHECK(channel);
-  DisconnectTransportChannelSignals();
-  transport_channel_ = channel;
-  ConnectTransportChannelSignals();
-  if (!was_ever_writable_ && channel->writable()) {
-    was_ever_writable_ = true;
-    // New channel is writable, now we can start the SCTP connection if Start
-    // was called already.
-    if (started_) {
-      RTC_DCHECK(!sock_);
-      Connect();
-    }
-  }
-}
-
-bool SctpTransport::Start(int local_sctp_port, int remote_sctp_port) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (local_sctp_port == -1) {
-    local_sctp_port = kSctpDefaultPort;
-  }
-  if (remote_sctp_port == -1) {
-    remote_sctp_port = kSctpDefaultPort;
-  }
-  if (started_) {
-    if (local_sctp_port != local_port_ || remote_sctp_port != remote_port_) {
-      LOG(LS_ERROR) << "Can't change SCTP port after SCTP association formed.";
-      return false;
-    }
-    return true;
-  }
-  local_port_ = local_sctp_port;
-  remote_port_ = remote_sctp_port;
-  started_ = true;
-  RTC_DCHECK(!sock_);
-  // Only try to connect if the DTLS channel has been writable before
-  // (indicating that the DTLS handshake is complete).
-  if (was_ever_writable_) {
-    return Connect();
-  }
-  return true;
-}
-
-bool SctpTransport::OpenStream(int sid) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (sid > kMaxSctpSid) {
-    LOG(LS_WARNING) << debug_name_ << "->OpenStream(...): "
-                    << "Not adding data stream "
-                    << "with sid=" << sid << " because sid is too high.";
-    return false;
-  } else if (open_streams_.find(sid) != open_streams_.end()) {
-    LOG(LS_WARNING) << debug_name_ << "->OpenStream(...): "
-                    << "Not adding data stream "
-                    << "with sid=" << sid << " because stream is already open.";
-    return false;
-  } else if (queued_reset_streams_.find(sid) != queued_reset_streams_.end() ||
-             sent_reset_streams_.find(sid) != sent_reset_streams_.end()) {
-    LOG(LS_WARNING) << debug_name_ << "->OpenStream(...): "
-                    << "Not adding data stream "
-                    << " with sid=" << sid
-                    << " because stream is still closing.";
-    return false;
-  }
-
-  open_streams_.insert(sid);
-  return true;
-}
-
-bool SctpTransport::ResetStream(int sid) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  StreamSet::iterator found = open_streams_.find(sid);
-  if (found == open_streams_.end()) {
-    LOG(LS_WARNING) << debug_name_ << "->ResetStream(" << sid << "): "
-                    << "stream not found.";
-    return false;
-  } else {
-    LOG(LS_VERBOSE) << debug_name_ << "->ResetStream(" << sid << "): "
-                    << "Removing and queuing RE-CONFIG chunk.";
-    open_streams_.erase(found);
-  }
-
-  // SCTP won't let you have more than one stream reset pending at a time, but
-  // you can close multiple streams in a single reset.  So, we keep an internal
-  // queue of streams-to-reset, and send them as one reset message in
-  // SendQueuedStreamResets().
-  queued_reset_streams_.insert(sid);
-
-  // Signal our stream-reset logic that it should try to send now, if it can.
-  SendQueuedStreamResets();
-
-  // The stream will actually get removed when we get the acknowledgment.
-  return true;
-}
-
-bool SctpTransport::SendData(const SendDataParams& params,
-                             const rtc::CopyOnWriteBuffer& payload,
-                             SendDataResult* result) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (result) {
-    // Preset |result| to assume an error.  If SendData succeeds, we'll
-    // overwrite |*result| once more at the end.
-    *result = SDR_ERROR;
-  }
-
-  if (!sock_) {
-    LOG(LS_WARNING) << debug_name_ << "->SendData(...): "
-                    << "Not sending packet with sid=" << params.sid
-                    << " len=" << payload.size() << " before Start().";
-    return false;
-  }
-
-  if (params.type != DMT_CONTROL &&
-      open_streams_.find(params.sid) == open_streams_.end()) {
-    LOG(LS_WARNING) << debug_name_ << "->SendData(...): "
-                    << "Not sending data because sid is unknown: "
-                    << params.sid;
-    return false;
-  }
-
-  // Send data using SCTP.
-  ssize_t send_res = 0;  // result from usrsctp_sendv.
-  struct sctp_sendv_spa spa = {0};
-  spa.sendv_flags |= SCTP_SEND_SNDINFO_VALID;
-  spa.sendv_sndinfo.snd_sid = params.sid;
-  spa.sendv_sndinfo.snd_ppid = rtc::HostToNetwork32(GetPpid(params.type));
-
-  // Ordered implies reliable.
-  if (!params.ordered) {
-    spa.sendv_sndinfo.snd_flags |= SCTP_UNORDERED;
-    if (params.max_rtx_count >= 0 || params.max_rtx_ms == 0) {
-      spa.sendv_flags |= SCTP_SEND_PRINFO_VALID;
-      spa.sendv_prinfo.pr_policy = SCTP_PR_SCTP_RTX;
-      spa.sendv_prinfo.pr_value = params.max_rtx_count;
-    } else {
-      spa.sendv_flags |= SCTP_SEND_PRINFO_VALID;
-      spa.sendv_prinfo.pr_policy = SCTP_PR_SCTP_TTL;
-      spa.sendv_prinfo.pr_value = params.max_rtx_ms;
-    }
-  }
-
-  // We don't fragment.
-  send_res = usrsctp_sendv(
-      sock_, payload.data(), static_cast<size_t>(payload.size()), NULL, 0, &spa,
-      rtc::checked_cast<socklen_t>(sizeof(spa)), SCTP_SENDV_SPA, 0);
-  if (send_res < 0) {
-    if (errno == SCTP_EWOULDBLOCK) {
-      *result = SDR_BLOCK;
-      ready_to_send_data_ = false;
-      LOG(LS_INFO) << debug_name_ << "->SendData(...): EWOULDBLOCK returned";
-    } else {
-      LOG_ERRNO(LS_ERROR) << "ERROR:" << debug_name_ << "->SendData(...): "
-                          << " usrsctp_sendv: ";
-    }
-    return false;
-  }
-  if (result) {
-    // Only way out now is success.
-    *result = SDR_SUCCESS;
-  }
-  return true;
-}
-
-bool SctpTransport::ReadyToSendData() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  return ready_to_send_data_;
-}
-
-void SctpTransport::ConnectTransportChannelSignals() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  transport_channel_->SignalWritableState.connect(
-      this, &SctpTransport::OnWritableState);
-  transport_channel_->SignalReadPacket.connect(this,
-                                               &SctpTransport::OnPacketRead);
-}
-
-void SctpTransport::DisconnectTransportChannelSignals() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  transport_channel_->SignalWritableState.disconnect(this);
-  transport_channel_->SignalReadPacket.disconnect(this);
-}
-
-bool SctpTransport::Connect() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  LOG(LS_VERBOSE) << debug_name_ << "->Connect().";
-
-  // If we already have a socket connection (which shouldn't ever happen), just
-  // return.
-  RTC_DCHECK(!sock_);
-  if (sock_) {
-    LOG(LS_ERROR) << debug_name_ << "->Connect(): Ignored as socket "
-                                    "is already established.";
-    return true;
-  }
-
-  // If no socket (it was closed) try to start it again. This can happen when
-  // the socket we are connecting to closes, does an sctp shutdown handshake,
-  // or behaves unexpectedly causing us to perform a CloseSctpSocket.
-  if (!OpenSctpSocket()) {
-    return false;
-  }
-
-  // Note: conversion from int to uint16_t happens on assignment.
-  sockaddr_conn local_sconn = GetSctpSockAddr(local_port_);
-  if (usrsctp_bind(sock_, reinterpret_cast<sockaddr*>(&local_sconn),
-                   sizeof(local_sconn)) < 0) {
-    LOG_ERRNO(LS_ERROR) << debug_name_
-                        << "->Connect(): " << ("Failed usrsctp_bind");
-    CloseSctpSocket();
-    return false;
-  }
-
-  // Note: conversion from int to uint16_t happens on assignment.
-  sockaddr_conn remote_sconn = GetSctpSockAddr(remote_port_);
-  int connect_result = usrsctp_connect(
-      sock_, reinterpret_cast<sockaddr*>(&remote_sconn), sizeof(remote_sconn));
-  if (connect_result < 0 && errno != SCTP_EINPROGRESS) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->Connect(): "
-                        << "Failed usrsctp_connect. got errno=" << errno
-                        << ", but wanted " << SCTP_EINPROGRESS;
-    CloseSctpSocket();
-    return false;
-  }
-  // Set the MTU and disable MTU discovery.
-  // We can only do this after usrsctp_connect or it has no effect.
-  sctp_paddrparams params = {{0}};
-  memcpy(&params.spp_address, &remote_sconn, sizeof(remote_sconn));
-  params.spp_flags = SPP_PMTUD_DISABLE;
-  params.spp_pathmtu = kSctpMtu;
-  if (usrsctp_setsockopt(sock_, IPPROTO_SCTP, SCTP_PEER_ADDR_PARAMS, &params,
-                         sizeof(params))) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->Connect(): "
-                        << "Failed to set SCTP_PEER_ADDR_PARAMS.";
-  }
-  // Since this is a fresh SCTP association, we'll always start out with empty
-  // queues, so "ReadyToSendData" should be true.
-  SetReadyToSendData();
-  return true;
-}
-
-bool SctpTransport::OpenSctpSocket() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (sock_) {
-    LOG(LS_WARNING) << debug_name_ << "->OpenSctpSocket(): "
-                    << "Ignoring attempt to re-create existing socket.";
-    return false;
-  }
-
-  UsrSctpWrapper::IncrementUsrSctpUsageCount();
-
-  // If kSendBufferSize isn't reflective of reality, we log an error, but we
-  // still have to do something reasonable here.  Look up what the buffer's
-  // real size is and set our threshold to something reasonable.
-  static const int kSendThreshold = usrsctp_sysctl_get_sctp_sendspace() / 2;
-
-  sock_ = usrsctp_socket(
-      AF_CONN, SOCK_STREAM, IPPROTO_SCTP, &UsrSctpWrapper::OnSctpInboundPacket,
-      &UsrSctpWrapper::SendThresholdCallback, kSendThreshold, this);
-  if (!sock_) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->OpenSctpSocket(): "
-                        << "Failed to create SCTP socket.";
-    UsrSctpWrapper::DecrementUsrSctpUsageCount();
-    return false;
-  }
-
-  if (!ConfigureSctpSocket()) {
-    usrsctp_close(sock_);
-    sock_ = nullptr;
-    UsrSctpWrapper::DecrementUsrSctpUsageCount();
-    return false;
-  }
-  // Register this class as an address for usrsctp. This is used by SCTP to
-  // direct the packets received (by the created socket) to this class.
-  usrsctp_register_address(this);
-  return true;
-}
-
-bool SctpTransport::ConfigureSctpSocket() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  RTC_DCHECK(sock_);
-  // Make the socket non-blocking. Connect, close, shutdown etc will not block
-  // the thread waiting for the socket operation to complete.
-  if (usrsctp_set_non_blocking(sock_, 1) < 0) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->ConfigureSctpSocket(): "
-                        << "Failed to set SCTP to non blocking.";
-    return false;
-  }
-
-  // This ensures that the usrsctp close call deletes the association. This
-  // prevents usrsctp from calling OnSctpOutboundPacket with references to
-  // this class as the address.
-  linger linger_opt;
-  linger_opt.l_onoff = 1;
-  linger_opt.l_linger = 0;
-  if (usrsctp_setsockopt(sock_, SOL_SOCKET, SO_LINGER, &linger_opt,
-                         sizeof(linger_opt))) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->ConfigureSctpSocket(): "
-                        << "Failed to set SO_LINGER.";
-    return false;
-  }
-
-  // Enable stream ID resets.
-  struct sctp_assoc_value stream_rst;
-  stream_rst.assoc_id = SCTP_ALL_ASSOC;
-  stream_rst.assoc_value = 1;
-  if (usrsctp_setsockopt(sock_, IPPROTO_SCTP, SCTP_ENABLE_STREAM_RESET,
-                         &stream_rst, sizeof(stream_rst))) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->ConfigureSctpSocket(): "
-
-                        << "Failed to set SCTP_ENABLE_STREAM_RESET.";
-    return false;
-  }
-
-  // Nagle.
-  uint32_t nodelay = 1;
-  if (usrsctp_setsockopt(sock_, IPPROTO_SCTP, SCTP_NODELAY, &nodelay,
-                         sizeof(nodelay))) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->ConfigureSctpSocket(): "
-                        << "Failed to set SCTP_NODELAY.";
-    return false;
-  }
-
-  // Subscribe to SCTP event notifications.
-  int event_types[] = {SCTP_ASSOC_CHANGE, SCTP_PEER_ADDR_CHANGE,
-                       SCTP_SEND_FAILED_EVENT, SCTP_SENDER_DRY_EVENT,
-                       SCTP_STREAM_RESET_EVENT};
-  struct sctp_event event = {0};
-  event.se_assoc_id = SCTP_ALL_ASSOC;
-  event.se_on = 1;
-  for (size_t i = 0; i < arraysize(event_types); i++) {
-    event.se_type = event_types[i];
-    if (usrsctp_setsockopt(sock_, IPPROTO_SCTP, SCTP_EVENT, &event,
-                           sizeof(event)) < 0) {
-      LOG_ERRNO(LS_ERROR) << debug_name_ << "->ConfigureSctpSocket(): "
-
-                          << "Failed to set SCTP_EVENT type: " << event.se_type;
-      return false;
-    }
-  }
-  return true;
-}
-
-void SctpTransport::CloseSctpSocket() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (sock_) {
-    // We assume that SO_LINGER option is set to close the association when
-    // close is called. This means that any pending packets in usrsctp will be
-    // discarded instead of being sent.
-    usrsctp_close(sock_);
-    sock_ = nullptr;
-    usrsctp_deregister_address(this);
-    UsrSctpWrapper::DecrementUsrSctpUsageCount();
-    ready_to_send_data_ = false;
-  }
-}
-
-bool SctpTransport::SendQueuedStreamResets() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (!sent_reset_streams_.empty() || queued_reset_streams_.empty()) {
-    return true;
-  }
-
-  LOG(LS_VERBOSE) << "SendQueuedStreamResets[" << debug_name_ << "]: Sending ["
-                  << ListStreams(queued_reset_streams_) << "], Open: ["
-                  << ListStreams(open_streams_) << "], Sent: ["
-                  << ListStreams(sent_reset_streams_) << "]";
-
-  const size_t num_streams = queued_reset_streams_.size();
-  const size_t num_bytes =
-      sizeof(struct sctp_reset_streams) + (num_streams * sizeof(uint16_t));
-
-  std::vector<uint8_t> reset_stream_buf(num_bytes, 0);
-  struct sctp_reset_streams* resetp =
-      reinterpret_cast<sctp_reset_streams*>(&reset_stream_buf[0]);
-  resetp->srs_assoc_id = SCTP_ALL_ASSOC;
-  resetp->srs_flags = SCTP_STREAM_RESET_INCOMING | SCTP_STREAM_RESET_OUTGOING;
-  resetp->srs_number_streams = rtc::checked_cast<uint16_t>(num_streams);
-  int result_idx = 0;
-  for (StreamSet::iterator it = queued_reset_streams_.begin();
-       it != queued_reset_streams_.end(); ++it) {
-    resetp->srs_stream_list[result_idx++] = *it;
-  }
-
-  int ret =
-      usrsctp_setsockopt(sock_, IPPROTO_SCTP, SCTP_RESET_STREAMS, resetp,
-                         rtc::checked_cast<socklen_t>(reset_stream_buf.size()));
-  if (ret < 0) {
-    LOG_ERRNO(LS_ERROR) << debug_name_ << "->SendQueuedStreamResets(): "
-                                          "Failed to send a stream reset for "
-                        << num_streams << " streams";
-    return false;
-  }
-
-  // sent_reset_streams_ is empty, and all the queued_reset_streams_ go into
-  // it now.
-  queued_reset_streams_.swap(sent_reset_streams_);
-  return true;
-}
-
-void SctpTransport::SetReadyToSendData() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (!ready_to_send_data_) {
-    ready_to_send_data_ = true;
-    SignalReadyToSendData();
-  }
-}
-
-void SctpTransport::OnWritableState(rtc::PacketTransportInterface* transport) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  RTC_DCHECK_EQ(transport_channel_, transport);
-  if (!was_ever_writable_ && transport->writable()) {
-    was_ever_writable_ = true;
-    if (started_) {
-      Connect();
-    }
-  }
-}
-
-// Called by network interface when a packet has been received.
-void SctpTransport::OnPacketRead(rtc::PacketTransportInterface* transport,
-                                 const char* data,
-                                 size_t len,
-                                 const rtc::PacketTime& packet_time,
-                                 int flags) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  RTC_DCHECK_EQ(transport_channel_, transport);
-  TRACE_EVENT0("webrtc", "SctpTransport::OnPacketRead");
-
-  // TODO(pthatcher): Do this in a more robust way by checking for
-  // SCTP or DTLS.
-  if (IsRtpPacket(data, len)) {
-    return;
-  }
-
-  LOG(LS_VERBOSE) << debug_name_ << "->OnPacketRead(...): "
-                  << " length=" << len << ", started: " << started_;
-  // Only give receiving packets to usrsctp after if connected. This enables two
-  // peers to each make a connect call, but for them not to receive an INIT
-  // packet before they have called connect; least the last receiver of the INIT
-  // packet will have called connect, and a connection will be established.
-  if (sock_) {
-    // Pass received packet to SCTP stack. Once processed by usrsctp, the data
-    // will be will be given to the global OnSctpInboundData, and then,
-    // marshalled by the AsyncInvoker.
-    VerboseLogPacket(data, len, SCTP_DUMP_INBOUND);
-    usrsctp_conninput(this, data, len, 0);
-  } else {
-    // TODO(ldixon): Consider caching the packet for very slightly better
-    // reliability.
-  }
-}
-
-void SctpTransport::OnSendThresholdCallback() {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  SetReadyToSendData();
-}
-
-sockaddr_conn SctpTransport::GetSctpSockAddr(int port) {
-  sockaddr_conn sconn = {0};
-  sconn.sconn_family = AF_CONN;
-#ifdef HAVE_SCONN_LEN
-  sconn.sconn_len = sizeof(sockaddr_conn);
-#endif
-  // Note: conversion from int to uint16_t happens here.
-  sconn.sconn_port = rtc::HostToNetwork16(port);
-  sconn.sconn_addr = this;
-  return sconn;
-}
-
-void SctpTransport::OnPacketFromSctpToNetwork(
-    const rtc::CopyOnWriteBuffer& buffer) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  if (buffer.size() > (kSctpMtu)) {
-    LOG(LS_ERROR) << debug_name_ << "->OnPacketFromSctpToNetwork(...): "
-                  << "SCTP seems to have made a packet that is bigger "
-                  << "than its official MTU: " << buffer.size() << " vs max of "
-                  << kSctpMtu;
-  }
-  TRACE_EVENT0("webrtc", "SctpTransport::OnPacketFromSctpToNetwork");
-
-  // Don't create noise by trying to send a packet when the DTLS channel isn't
-  // even writable.
-  if (!transport_channel_->writable()) {
-    return;
-  }
-
-  // Bon voyage.
-  transport_channel_->SendPacket(buffer.data<char>(), buffer.size(),
-                                 rtc::PacketOptions(), PF_NORMAL);
-}
-
-void SctpTransport::OnInboundPacketFromSctpToChannel(
-    const rtc::CopyOnWriteBuffer& buffer,
-    ReceiveDataParams params,
-    int flags) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  LOG(LS_VERBOSE) << debug_name_ << "->OnInboundPacketFromSctpToChannel(...): "
-                  << "Received SCTP data:"
-                  << " sid=" << params.sid
-                  << " notification: " << (flags & MSG_NOTIFICATION)
-                  << " length=" << buffer.size();
-  // Sending a packet with data == NULL (no data) is SCTPs "close the
-  // connection" message. This sets sock_ = NULL;
-  if (!buffer.size() || !buffer.data()) {
-    LOG(LS_INFO) << debug_name_ << "->OnInboundPacketFromSctpToChannel(...): "
-                                   "No data, closing.";
-    return;
-  }
-  if (flags & MSG_NOTIFICATION) {
-    OnNotificationFromSctp(buffer);
-  } else {
-    OnDataFromSctpToChannel(params, buffer);
-  }
-}
-
-void SctpTransport::OnDataFromSctpToChannel(
-    const ReceiveDataParams& params,
-    const rtc::CopyOnWriteBuffer& buffer) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  LOG(LS_VERBOSE) << debug_name_ << "->OnDataFromSctpToChannel(...): "
-                  << "Posting with length: " << buffer.size() << " on stream "
-                  << params.sid;
-  // Reports all received messages to upper layers, no matter whether the sid
-  // is known.
-  SignalDataReceived(params, buffer);
-}
-
-void SctpTransport::OnNotificationFromSctp(
-    const rtc::CopyOnWriteBuffer& buffer) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  const sctp_notification& notification =
-      reinterpret_cast<const sctp_notification&>(*buffer.data());
-  RTC_DCHECK(notification.sn_header.sn_length == buffer.size());
-
-  // TODO(ldixon): handle notifications appropriately.
-  switch (notification.sn_header.sn_type) {
-    case SCTP_ASSOC_CHANGE:
-      LOG(LS_VERBOSE) << "SCTP_ASSOC_CHANGE";
-      OnNotificationAssocChange(notification.sn_assoc_change);
-      break;
-    case SCTP_REMOTE_ERROR:
-      LOG(LS_INFO) << "SCTP_REMOTE_ERROR";
-      break;
-    case SCTP_SHUTDOWN_EVENT:
-      LOG(LS_INFO) << "SCTP_SHUTDOWN_EVENT";
-      break;
-    case SCTP_ADAPTATION_INDICATION:
-      LOG(LS_INFO) << "SCTP_ADAPTATION_INDICATION";
-      break;
-    case SCTP_PARTIAL_DELIVERY_EVENT:
-      LOG(LS_INFO) << "SCTP_PARTIAL_DELIVERY_EVENT";
-      break;
-    case SCTP_AUTHENTICATION_EVENT:
-      LOG(LS_INFO) << "SCTP_AUTHENTICATION_EVENT";
-      break;
-    case SCTP_SENDER_DRY_EVENT:
-      LOG(LS_VERBOSE) << "SCTP_SENDER_DRY_EVENT";
-      SetReadyToSendData();
-      break;
-    // TODO(ldixon): Unblock after congestion.
-    case SCTP_NOTIFICATIONS_STOPPED_EVENT:
-      LOG(LS_INFO) << "SCTP_NOTIFICATIONS_STOPPED_EVENT";
-      break;
-    case SCTP_SEND_FAILED_EVENT:
-      LOG(LS_INFO) << "SCTP_SEND_FAILED_EVENT";
-      break;
-    case SCTP_STREAM_RESET_EVENT:
-      OnStreamResetEvent(&notification.sn_strreset_event);
-      break;
-    case SCTP_ASSOC_RESET_EVENT:
-      LOG(LS_INFO) << "SCTP_ASSOC_RESET_EVENT";
-      break;
-    case SCTP_STREAM_CHANGE_EVENT:
-      LOG(LS_INFO) << "SCTP_STREAM_CHANGE_EVENT";
-      // An acknowledgment we get after our stream resets have gone through,
-      // if they've failed.  We log the message, but don't react -- we don't
-      // keep around the last-transmitted set of SSIDs we wanted to close for
-      // error recovery.  It doesn't seem likely to occur, and if so, likely
-      // harmless within the lifetime of a single SCTP association.
-      break;
-    default:
-      LOG(LS_WARNING) << "Unknown SCTP event: "
-                      << notification.sn_header.sn_type;
-      break;
-  }
-}
-
-void SctpTransport::OnNotificationAssocChange(const sctp_assoc_change& change) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  switch (change.sac_state) {
-    case SCTP_COMM_UP:
-      LOG(LS_VERBOSE) << "Association change SCTP_COMM_UP";
-      break;
-    case SCTP_COMM_LOST:
-      LOG(LS_INFO) << "Association change SCTP_COMM_LOST";
-      break;
-    case SCTP_RESTART:
-      LOG(LS_INFO) << "Association change SCTP_RESTART";
-      break;
-    case SCTP_SHUTDOWN_COMP:
-      LOG(LS_INFO) << "Association change SCTP_SHUTDOWN_COMP";
-      break;
-    case SCTP_CANT_STR_ASSOC:
-      LOG(LS_INFO) << "Association change SCTP_CANT_STR_ASSOC";
-      break;
-    default:
-      LOG(LS_INFO) << "Association change UNKNOWN";
-      break;
-  }
-}
-
-void SctpTransport::OnStreamResetEvent(
-    const struct sctp_stream_reset_event* evt) {
-  RTC_DCHECK_RUN_ON(network_thread_);
-  // A stream reset always involves two RE-CONFIG chunks for us -- we always
-  // simultaneously reset a sid's sequence number in both directions.  The
-  // requesting side transmits a RE-CONFIG chunk and waits for the peer to send
-  // one back.  Both sides get this SCTP_STREAM_RESET_EVENT when they receive
-  // RE-CONFIGs.
-  const int num_sids = (evt->strreset_length - sizeof(*evt)) /
-                       sizeof(evt->strreset_stream_list[0]);
-  LOG(LS_VERBOSE) << "SCTP_STREAM_RESET_EVENT(" << debug_name_
-                  << "): Flags = 0x" << std::hex << evt->strreset_flags << " ("
-                  << ListFlags(evt->strreset_flags) << ")";
-  LOG(LS_VERBOSE) << "Assoc = " << evt->strreset_assoc_id << ", Streams = ["
-                  << ListArray(evt->strreset_stream_list, num_sids)
-                  << "], Open: [" << ListStreams(open_streams_) << "], Q'd: ["
-                  << ListStreams(queued_reset_streams_) << "], Sent: ["
-                  << ListStreams(sent_reset_streams_) << "]";
-
-  // If both sides try to reset some streams at the same time (even if they're
-  // disjoint sets), we can get reset failures.
-  if (evt->strreset_flags & SCTP_STREAM_RESET_FAILED) {
-    // OK, just try again.  The stream IDs sent over when the RESET_FAILED flag
-    // is set seem to be garbage values.  Ignore them.
-    queued_reset_streams_.insert(sent_reset_streams_.begin(),
-                                 sent_reset_streams_.end());
-    sent_reset_streams_.clear();
-
-  } else if (evt->strreset_flags & SCTP_STREAM_RESET_INCOMING_SSN) {
-    // Each side gets an event for each direction of a stream.  That is,
-    // closing sid k will make each side receive INCOMING and OUTGOING reset
-    // events for k.  As per RFC6525, Section 5, paragraph 2, each side will
-    // get an INCOMING event first.
-    for (int i = 0; i < num_sids; i++) {
-      const int stream_id = evt->strreset_stream_list[i];
-
-      // See if this stream ID was closed by our peer or ourselves.
-      StreamSet::iterator it = sent_reset_streams_.find(stream_id);
-
-      // The reset was requested locally.
-      if (it != sent_reset_streams_.end()) {
-        LOG(LS_VERBOSE) << "SCTP_STREAM_RESET_EVENT(" << debug_name_
-                        << "): local sid " << stream_id << " acknowledged.";
-        sent_reset_streams_.erase(it);
-
-      } else if ((it = open_streams_.find(stream_id)) != open_streams_.end()) {
-        // The peer requested the reset.
-        LOG(LS_VERBOSE) << "SCTP_STREAM_RESET_EVENT(" << debug_name_
-                        << "): closing sid " << stream_id;
-        open_streams_.erase(it);
-        SignalStreamClosedRemotely(stream_id);
-
-      } else if ((it = queued_reset_streams_.find(stream_id)) !=
-                 queued_reset_streams_.end()) {
-        // The peer requested the reset, but there was a local reset
-        // queued.
-        LOG(LS_VERBOSE) << "SCTP_STREAM_RESET_EVENT(" << debug_name_
-                        << "): double-sided close for sid " << stream_id;
-        // Both sides want the stream closed, and the peer got to send the
-        // RE-CONFIG first.  Treat it like the local Remove(Send|Recv)Stream
-        // finished quickly.
-        queued_reset_streams_.erase(it);
-
-      } else {
-        // This stream is unknown.  Sometimes this can be from an
-        // RESET_FAILED-related retransmit.
-        LOG(LS_VERBOSE) << "SCTP_STREAM_RESET_EVENT(" << debug_name_
-                        << "): Unknown sid " << stream_id;
-      }
-    }
-  }
-
-  // Always try to send the queued RESET because this call indicates that the
-  // last local RESET or remote RESET has made some progress.
-  SendQueuedStreamResets();
-}
-
-}  // namespace cricket