sctp: Add DcsctpTransport based on dcSCTP

Bug: webrtc:12614
Change-Id: Ie710621610fff9f8bb6c7d800419675892d6a70c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215680
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33935}

media/BUILD.gn

@@ -387,6 +387,36 @@ rtc_source_set("rtc_data_sctp_transport_internal") {
   ]
 }
 
+if (rtc_build_dcsctp) {
+  rtc_library("rtc_data_dcsctp_transport") {
+    sources = [
+      "sctp/dcsctp_transport.cc",
+      "sctp/dcsctp_transport.h",
+    ]
+    deps = [
+      ":rtc_data_sctp_transport_internal",
+      "../api:array_view",
+      "../media:rtc_media_base",
+      "../net/dcsctp/public:socket",
+      "../net/dcsctp/public:types",
+      "../net/dcsctp/socket:dcsctp_socket",
+      "../net/dcsctp/timer:task_queue_timeout",
+      "../p2p:rtc_p2p",
+      "../rtc_base:checks",
+      "../rtc_base:rtc_base_approved",
+      "../rtc_base:threading",
+      "../rtc_base/task_utils:pending_task_safety_flag",
+      "../rtc_base/task_utils:to_queued_task",
+      "../rtc_base/third_party/sigslot:sigslot",
+      "../system_wrappers",
+    ]
+    absl_deps += [
+      "//third_party/abseil-cpp/absl/strings:strings",
+      "//third_party/abseil-cpp/absl/types:optional",
+    ]
+  }
+}
+
 if (rtc_build_usrsctp) {
   rtc_library("rtc_data_usrsctp_transport") {
     defines = [
@@ -426,11 +456,22 @@ rtc_library("rtc_data_sctp_transport_factory") {
     ":rtc_data_sctp_transport_internal",
     "../api/transport:sctp_transport_factory_interface",
     "../rtc_base:threading",
+    "../rtc_base/experiments:field_trial_parser",
     "../rtc_base/system:unused",
   ]
 
   if (rtc_enable_sctp) {
-    assert(rtc_build_usrsctp, "An SCTP backend is required to enable SCTP")
+    assert(rtc_build_dcsctp || rtc_build_usrsctp,
+           "An SCTP backend is required to enable SCTP")
+  }
+
+  if (rtc_build_dcsctp) {
+    defines += [ "WEBRTC_HAVE_DCSCTP" ]
+    deps += [
+      ":rtc_data_dcsctp_transport",
+      "../system_wrappers",
+      "../system_wrappers:field_trial",
+    ]
   }
 
   if (rtc_build_usrsctp) {

media/DEPS

@@ -11,6 +11,7 @@ include_rules = [
   "+modules/video_capture",
   "+modules/video_coding",
   "+modules/video_coding/utility",
+  "+net/dcsctp",
   "+p2p",
   "+sound",
   "+system_wrappers",

media/sctp/dcsctp_transport.cc

@@ -0,0 +1,483 @@
+/*
+ *  Copyright 2021 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 "media/sctp/dcsctp_transport.h"
+
+#include <cstdint>
+#include <utility>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "media/base/media_channel.h"
+#include "net/dcsctp/public/types.h"
+#include "net/dcsctp/socket/dcsctp_socket.h"
+#include "p2p/base/packet_transport_internal.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/thread.h"
+#include "rtc_base/trace_event.h"
+#include "system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+namespace {
+
+enum class WebrtcPPID : dcsctp::PPID::UnderlyingType {
+  kNone = 0,  // No protocol is specified.
+  // https://www.rfc-editor.org/rfc/rfc8832.html#section-8.1
+  kDCEP = 50,
+  // https://www.rfc-editor.org/rfc/rfc8831.html#section-8
+  kString = 51,
+  kBinaryPartial = 52,  // Deprecated
+  kBinary = 53,
+  kStringPartial = 54,  // Deprecated
+  kStringEmpty = 56,
+  kBinaryEmpty = 57,
+};
+
+WebrtcPPID ToPPID(cricket::DataMessageType message_type, size_t size) {
+  switch (message_type) {
+    case cricket::DMT_CONTROL:
+      return WebrtcPPID::kDCEP;
+    case cricket::DMT_TEXT:
+      return size > 0 ? WebrtcPPID::kString : WebrtcPPID::kStringEmpty;
+    case cricket::DMT_BINARY:
+      return size > 0 ? WebrtcPPID::kBinary : WebrtcPPID::kBinaryEmpty;
+    default:
+      RTC_NOTREACHED();
+  }
+  return WebrtcPPID::kNone;
+}
+
+absl::optional<cricket::DataMessageType> ToDataMessageType(dcsctp::PPID ppid) {
+  switch (static_cast<WebrtcPPID>(ppid.value())) {
+    case WebrtcPPID::kNone:
+      return cricket::DMT_NONE;
+    case WebrtcPPID::kDCEP:
+      return cricket::DMT_CONTROL;
+    case WebrtcPPID::kString:
+    case WebrtcPPID::kStringPartial:
+    case WebrtcPPID::kStringEmpty:
+      return cricket::DMT_TEXT;
+    case WebrtcPPID::kBinary:
+    case WebrtcPPID::kBinaryPartial:
+    case WebrtcPPID::kBinaryEmpty:
+      return cricket::DMT_BINARY;
+  }
+  return absl::nullopt;
+}
+
+bool IsEmptyPPID(dcsctp::PPID ppid) {
+  WebrtcPPID webrtc_ppid = static_cast<WebrtcPPID>(ppid.value());
+  return webrtc_ppid == WebrtcPPID::kStringEmpty ||
+         webrtc_ppid == WebrtcPPID::kBinaryEmpty;
+}
+
+}  // namespace
+
+DcSctpTransport::DcSctpTransport(rtc::Thread* network_thread,
+                                 rtc::PacketTransportInternal* transport,
+                                 Clock* clock)
+    : network_thread_(network_thread),
+      transport_(transport),
+      clock_(clock),
+      random_(clock_->TimeInMicroseconds()),
+      task_queue_timeout_factory_(
+          *network_thread,
+          [this]() { return TimeMillis(); },
+          [this](dcsctp::TimeoutID timeout_id) {
+            socket_->HandleTimeout(timeout_id);
+          }) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  static int instance_count = 0;
+  rtc::StringBuilder sb;
+  sb << debug_name_ << instance_count++;
+  debug_name_ = sb.Release();
+  ConnectTransportSignals();
+}
+
+DcSctpTransport::~DcSctpTransport() {
+  if (socket_) {
+    socket_->Close();
+  }
+}
+
+void DcSctpTransport::SetDtlsTransport(
+    rtc::PacketTransportInternal* transport) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  DisconnectTransportSignals();
+  transport_ = transport;
+  ConnectTransportSignals();
+  MaybeConnectSocket();
+}
+
+bool DcSctpTransport::Start(int local_sctp_port,
+                            int remote_sctp_port,
+                            int max_message_size) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DCHECK(max_message_size > 0);
+
+  RTC_LOG(LS_INFO) << debug_name_ << "->Start(local=" << local_sctp_port
+                   << ", remote=" << remote_sctp_port
+                   << ", max_message_size=" << max_message_size << ")";
+
+  if (!socket_) {
+    dcsctp::DcSctpOptions options;
+    options.local_port = local_sctp_port;
+    options.remote_port = remote_sctp_port;
+    options.max_message_size = max_message_size;
+
+    socket_ = std::make_unique<dcsctp::DcSctpSocket>(debug_name_, *this,
+                                                     nullptr, options);
+  } else {
+    if (local_sctp_port != socket_->options().local_port ||
+        remote_sctp_port != socket_->options().remote_port) {
+      RTC_LOG(LS_ERROR)
+          << debug_name_ << "->Start(local=" << local_sctp_port
+          << ", remote=" << remote_sctp_port
+          << "): Can't change ports on already started transport.";
+      return false;
+    }
+    socket_->SetMaxMessageSize(max_message_size);
+  }
+
+  MaybeConnectSocket();
+
+  return true;
+}
+
+bool DcSctpTransport::OpenStream(int sid) {
+  RTC_LOG(LS_INFO) << debug_name_ << "->OpenStream(" << sid << ").";
+  if (!socket_) {
+    RTC_LOG(LS_ERROR) << debug_name_ << "->OpenStream(sid=" << sid
+                      << "): Transport is not started.";
+    return false;
+  }
+  return true;
+}
+
+bool DcSctpTransport::ResetStream(int sid) {
+  RTC_LOG(LS_INFO) << debug_name_ << "->ResetStream(" << sid << ").";
+  if (!socket_) {
+    RTC_LOG(LS_ERROR) << debug_name_ << "->OpenStream(sid=" << sid
+                      << "): Transport is not started.";
+    return false;
+  }
+  dcsctp::StreamID streams[1] = {dcsctp::StreamID(static_cast<uint16_t>(sid))};
+  socket_->ResetStreams(streams);
+  return true;
+}
+
+bool DcSctpTransport::SendData(const cricket::SendDataParams& params,
+                               const rtc::CopyOnWriteBuffer& payload,
+                               cricket::SendDataResult* result) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+
+  RTC_LOG(LS_VERBOSE) << debug_name_ << "->SendData(sid=" << params.sid
+                      << ", type=" << params.type
+                      << ", length=" << payload.size() << ").";
+
+  if (!socket_) {
+    RTC_LOG(LS_ERROR) << debug_name_
+                      << "->SendData(...): Transport is not started.";
+    *result = cricket::SDR_ERROR;
+    return false;
+  }
+
+  auto max_message_size = socket_->options().max_message_size;
+  if (max_message_size > 0 && payload.size() > max_message_size) {
+    RTC_LOG(LS_ERROR) << debug_name_
+                      << "->SendData(...): "
+                         "Trying to send packet bigger "
+                         "than the max message size: "
+                      << payload.size() << " vs max of " << max_message_size;
+    *result = cricket::SDR_ERROR;
+    return false;
+  }
+
+  std::vector<uint8_t> message_payload(payload.cdata(),
+                                       payload.cdata() + payload.size());
+  if (message_payload.empty()) {
+    // https://www.rfc-editor.org/rfc/rfc8831.html#section-6.6
+    // SCTP does not support the sending of empty user messages. Therefore, if
+    // an empty message has to be sent, the appropriate PPID (WebRTC String
+    // Empty or WebRTC Binary Empty) is used, and the SCTP user message of one
+    // zero byte is sent.
+    message_payload.push_back('\0');
+  }
+
+  dcsctp::DcSctpMessage message(
+      dcsctp::StreamID(static_cast<uint16_t>(params.sid)),
+      dcsctp::PPID(static_cast<uint16_t>(ToPPID(params.type, payload.size()))),
+      std::move(message_payload));
+
+  dcsctp::SendOptions send_options;
+  send_options.unordered = dcsctp::IsUnordered(!params.ordered);
+  if (params.max_rtx_ms > 0)
+    send_options.lifetime = dcsctp::DurationMs(params.max_rtx_ms);
+  if (params.max_rtx_count > 0)
+    send_options.max_retransmissions =
+        static_cast<size_t>(params.max_rtx_count);
+
+  auto error = socket_->Send(std::move(message), send_options);
+  switch (error) {
+    case dcsctp::SendStatus::kSuccess:
+      *result = cricket::SDR_SUCCESS;
+      break;
+    case dcsctp::SendStatus::kErrorResourceExhaustion:
+      *result = cricket::SDR_BLOCK;
+      ready_to_send_data_ = false;
+      break;
+    default:
+      RTC_LOG(LS_ERROR) << debug_name_
+                        << "->SendData(...): send() failed with error "
+                        << dcsctp::ToString(error) << ".";
+      *result = cricket::SDR_ERROR;
+  }
+
+  return *result == cricket::SDR_SUCCESS;
+}
+
+bool DcSctpTransport::ReadyToSendData() {
+  return ready_to_send_data_;
+}
+
+int DcSctpTransport::max_message_size() const {
+  if (!socket_) {
+    RTC_LOG(LS_ERROR) << debug_name_
+                      << "->max_message_size(...): Transport is not started.";
+    return 0;
+  }
+  return socket_->options().max_message_size;
+}
+
+absl::optional<int> DcSctpTransport::max_outbound_streams() const {
+  if (!socket_)
+    return absl::nullopt;
+  return socket_->options().announced_maximum_outgoing_streams;
+}
+
+absl::optional<int> DcSctpTransport::max_inbound_streams() const {
+  if (!socket_)
+    return absl::nullopt;
+  return socket_->options().announced_maximum_incoming_streams;
+}
+
+void DcSctpTransport::set_debug_name_for_testing(const char* debug_name) {
+  debug_name_ = debug_name;
+}
+
+void DcSctpTransport::SendPacket(rtc::ArrayView<const uint8_t> data) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DCHECK(socket_);
+
+  if (data.size() > (socket_->options().mtu)) {
+    RTC_LOG(LS_ERROR) << debug_name_
+                      << "->SendPacket(...): "
+                         "SCTP seems to have made a packet that is bigger "
+                         "than its official MTU: "
+                      << data.size() << " vs max of " << socket_->options().mtu;
+    return;
+  }
+  TRACE_EVENT0("webrtc", "DcSctpTransport::SendPacket");
+
+  if (!transport_ || !transport_->writable())
+    return;
+
+  RTC_LOG(LS_VERBOSE) << debug_name_ << "->SendPacket(length=" << data.size()
+                      << ")";
+
+  auto result =
+      transport_->SendPacket(reinterpret_cast<const char*>(data.data()),
+                             data.size(), rtc::PacketOptions(), 0);
+
+  if (result < 0) {
+    RTC_LOG(LS_ERROR) << debug_name_ << "->SendPacket(length=" << data.size()
+                      << ") failed with error: " << transport_->GetError()
+                      << ".";
+  }
+}
+
+std::unique_ptr<dcsctp::Timeout> DcSctpTransport::CreateTimeout() {
+  return task_queue_timeout_factory_.CreateTimeout();
+}
+
+dcsctp::TimeMs DcSctpTransport::TimeMillis() {
+  return dcsctp::TimeMs(clock_->TimeInMilliseconds());
+}
+
+uint32_t DcSctpTransport::GetRandomInt(uint32_t low, uint32_t high) {
+  return random_.Rand(low, high);
+}
+
+void DcSctpTransport::NotifyOutgoingMessageBufferEmpty() {
+  RTC_LOG(LS_VERBOSE) << debug_name_ << "->NotifyOutgoingMessageBufferEmpty()";
+  if (!ready_to_send_data_) {
+    ready_to_send_data_ = true;
+    SignalReadyToSendData();
+  }
+}
+
+void DcSctpTransport::OnMessageReceived(dcsctp::DcSctpMessage message) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_LOG(LS_INFO) << debug_name_
+                   << "->OnMessageReceived(sid=" << message.stream_id().value()
+                   << ", ppid=" << message.ppid().value()
+                   << ", length=" << message.payload().size() << ").";
+  cricket::ReceiveDataParams receive_data_params;
+  receive_data_params.sid = message.stream_id().value();
+  auto type = ToDataMessageType(message.ppid());
+  if (!type.has_value()) {
+    RTC_LOG(LS_VERBOSE) << debug_name_
+                        << "->OnMessageReceived(): Received an unknown PPID "
+                        << message.ppid().value()
+                        << " on an SCTP packet. Dropping.";
+  }
+  receive_data_params.type = *type;
+  // No seq_num available from dcSCTP
+  receive_data_params.seq_num = 0;
+  receive_buffer_.Clear();
+  if (!IsEmptyPPID(message.ppid()))
+    receive_buffer_.AppendData(message.payload().data(),
+                               message.payload().size());
+
+  SignalDataReceived(receive_data_params, receive_buffer_);
+}
+
+void DcSctpTransport::OnError(dcsctp::ErrorKind error,
+                              absl::string_view message) {
+  RTC_LOG(LS_ERROR) << debug_name_
+                    << "->OnError(error=" << dcsctp::ToString(error)
+                    << ", message=" << message << ").";
+}
+
+void DcSctpTransport::OnAborted(dcsctp::ErrorKind error,
+                                absl::string_view message) {
+  RTC_LOG(LS_ERROR) << debug_name_
+                    << "->OnAborted(error=" << dcsctp::ToString(error)
+                    << ", message=" << message << ").";
+  ready_to_send_data_ = false;
+}
+
+void DcSctpTransport::OnConnected() {
+  RTC_LOG(LS_INFO) << debug_name_ << "->OnConnected().";
+  ready_to_send_data_ = true;
+  SignalReadyToSendData();
+  SignalAssociationChangeCommunicationUp();
+}
+
+void DcSctpTransport::OnClosed() {
+  RTC_LOG(LS_INFO) << debug_name_ << "->OnClosed().";
+  ready_to_send_data_ = false;
+}
+
+void DcSctpTransport::OnConnectionRestarted() {
+  RTC_LOG(LS_INFO) << debug_name_ << "->OnConnectionRestarted().";
+}
+
+void DcSctpTransport::OnStreamsResetFailed(
+    rtc::ArrayView<const dcsctp::StreamID> outgoing_streams,
+    absl::string_view reason) {
+  // TODO(orphis): Need a test to check for correct behavior
+  for (auto& stream_id : outgoing_streams) {
+    RTC_LOG(LS_ERROR)
+        << debug_name_
+        << "->OnStreamsResetFailed(...): Outgoing stream reset failed"
+        << ", sid=" << stream_id.value() << ", reason: " << reason << ".";
+  }
+}
+
+void DcSctpTransport::OnStreamsResetPerformed(
+    rtc::ArrayView<const dcsctp::StreamID> outgoing_streams) {
+  for (auto& stream_id : outgoing_streams) {
+    RTC_LOG(LS_INFO) << debug_name_
+                     << "->OnStreamsResetPerformed(...): Outgoing stream reset"
+                     << ", sid=" << stream_id.value();
+    SignalClosingProcedureComplete(stream_id.value());
+  }
+}
+
+void DcSctpTransport::OnIncomingStreamsReset(
+    rtc::ArrayView<const dcsctp::StreamID> incoming_streams) {
+  for (auto& stream_id : incoming_streams) {
+    RTC_LOG(LS_INFO) << debug_name_
+                     << "->OnIncomingStreamsReset(...): Incoming stream reset"
+                     << ", sid=" << stream_id.value();
+    SignalClosingProcedureStartedRemotely(stream_id.value());
+    SignalClosingProcedureComplete(stream_id.value());
+  }
+}
+
+void DcSctpTransport::ConnectTransportSignals() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (!transport_) {
+    return;
+  }
+  transport_->SignalWritableState.connect(
+      this, &DcSctpTransport::OnTransportWritableState);
+  transport_->SignalReadPacket.connect(this,
+                                       &DcSctpTransport::OnTransportReadPacket);
+  transport_->SignalClosed.connect(this, &DcSctpTransport::OnTransportClosed);
+}
+
+void DcSctpTransport::DisconnectTransportSignals() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (!transport_) {
+    return;
+  }
+  transport_->SignalWritableState.disconnect(this);
+  transport_->SignalReadPacket.disconnect(this);
+  transport_->SignalClosed.disconnect(this);
+}
+
+void DcSctpTransport::OnTransportWritableState(
+    rtc::PacketTransportInternal* transport) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DCHECK_EQ(transport_, transport);
+
+  RTC_LOG(LS_INFO) << debug_name_ << "->OnTransportWritableState(), writable="
+                   << transport->writable();
+
+  MaybeConnectSocket();
+}
+
+void DcSctpTransport::OnTransportReadPacket(
+    rtc::PacketTransportInternal* transport,
+    const char* data,
+    size_t length,
+    const int64_t& /* packet_time_us */,
+    int flags) {
+  if (flags) {
+    // We are only interested in SCTP packets.
+    return;
+  }
+
+  RTC_LOG(LS_VERBOSE) << debug_name_
+                      << "->OnTransportReadPacket(), length=" << length;
+  if (socket_) {
+    socket_->ReceivePacket(rtc::ArrayView<const uint8_t>(
+        reinterpret_cast<const uint8_t*>(data), length));
+  }
+}
+
+void DcSctpTransport::OnTransportClosed(
+    rtc::PacketTransportInternal* transport) {
+  RTC_LOG(LS_VERBOSE) << debug_name_ << "->OnTransportClosed().";
+  SignalClosedAbruptly();
+}
+
+void DcSctpTransport::MaybeConnectSocket() {
+  if (transport_ && transport_->writable() && socket_ &&
+      socket_->state() == dcsctp::SocketState::kClosed) {
+    socket_->Connect();
+  }
+}
+}  // namespace webrtc

media/sctp/dcsctp_transport.h

@@ -0,0 +1,108 @@
+/*
+ *  Copyright (c) 2021 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 MEDIA_SCTP_DCSCTP_TRANSPORT_H_
+#define MEDIA_SCTP_DCSCTP_TRANSPORT_H_
+
+#include <memory>
+#include <string>
+
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "media/sctp/sctp_transport_internal.h"
+#include "net/dcsctp/public/dcsctp_options.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+#include "net/dcsctp/public/types.h"
+#include "net/dcsctp/timer/task_queue_timeout.h"
+#include "p2p/base/packet_transport_internal.h"
+#include "rtc_base/copy_on_write_buffer.h"
+#include "rtc_base/random.h"
+#include "rtc_base/third_party/sigslot/sigslot.h"
+#include "rtc_base/thread.h"
+#include "system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+class DcSctpTransport : public cricket::SctpTransportInternal,
+                        public dcsctp::DcSctpSocketCallbacks,
+                        public sigslot::has_slots<> {
+ public:
+  DcSctpTransport(rtc::Thread* network_thread,
+                  rtc::PacketTransportInternal* transport,
+                  Clock* clock);
+  ~DcSctpTransport() override;
+
+  // cricket::SctpTransportInternal
+  void SetDtlsTransport(rtc::PacketTransportInternal* transport) override;
+  bool Start(int local_sctp_port,
+             int remote_sctp_port,
+             int max_message_size) override;
+  bool OpenStream(int sid) override;
+  bool ResetStream(int sid) override;
+  bool SendData(const cricket::SendDataParams& params,
+                const rtc::CopyOnWriteBuffer& payload,
+                cricket::SendDataResult* result = nullptr) override;
+  bool ReadyToSendData() override;
+  int max_message_size() const override;
+  absl::optional<int> max_outbound_streams() const override;
+  absl::optional<int> max_inbound_streams() const override;
+  void set_debug_name_for_testing(const char* debug_name) override;
+
+ private:
+  // dcsctp::DcSctpSocketCallbacks
+  void SendPacket(rtc::ArrayView<const uint8_t> data) override;
+  std::unique_ptr<dcsctp::Timeout> CreateTimeout() override;
+  dcsctp::TimeMs TimeMillis() override;
+  uint32_t GetRandomInt(uint32_t low, uint32_t high) override;
+  void NotifyOutgoingMessageBufferEmpty() override;
+  void OnMessageReceived(dcsctp::DcSctpMessage message) override;
+  void OnError(dcsctp::ErrorKind error, absl::string_view message) override;
+  void OnAborted(dcsctp::ErrorKind error, absl::string_view message) override;
+  void OnConnected() override;
+  void OnClosed() override;
+  void OnConnectionRestarted() override;
+  void OnStreamsResetFailed(
+      rtc::ArrayView<const dcsctp::StreamID> outgoing_streams,
+      absl::string_view reason) override;
+  void OnStreamsResetPerformed(
+      rtc::ArrayView<const dcsctp::StreamID> outgoing_streams) override;
+  void OnIncomingStreamsReset(
+      rtc::ArrayView<const dcsctp::StreamID> incoming_streams) override;
+
+  // Transport callbacks
+  void ConnectTransportSignals();
+  void DisconnectTransportSignals();
+  void OnTransportWritableState(rtc::PacketTransportInternal* transport);
+  void OnTransportReadPacket(rtc::PacketTransportInternal* transport,
+                             const char* data,
+                             size_t length,
+                             const int64_t& /* packet_time_us */,
+                             int flags);
+  void OnTransportClosed(rtc::PacketTransportInternal* transport);
+
+  void MaybeConnectSocket();
+
+  rtc::Thread* network_thread_;
+  rtc::PacketTransportInternal* transport_;
+  Clock* clock_;
+  Random random_;
+
+  dcsctp::TaskQueueTimeoutFactory task_queue_timeout_factory_;
+  std::unique_ptr<dcsctp::DcSctpSocketInterface> socket_;
+  std::string debug_name_ = "DcSctpTransport";
+  rtc::CopyOnWriteBuffer receive_buffer_;
+
+  bool ready_to_send_data_ = false;
+};
+
+}  // namespace webrtc
+
+#endif  // MEDIA_SCTP_DCSCTP_TRANSPORT_H_

media/sctp/sctp_transport_factory.cc

@@ -12,6 +12,12 @@
 
 #include "rtc_base/system/unused.h"
 
+#ifdef WEBRTC_HAVE_DCSCTP
+#include "media/sctp/dcsctp_transport.h"          // nogncheck
+#include "system_wrappers/include/clock.h"        // nogncheck
+#include "system_wrappers/include/field_trial.h"  // nogncheck
+#endif
+
 #ifdef WEBRTC_HAVE_USRSCTP
 #include "media/sctp/usrsctp_transport.h"  // nogncheck
 #endif
@@ -19,14 +25,24 @@
 namespace cricket {
 
 SctpTransportFactory::SctpTransportFactory(rtc::Thread* network_thread)
-    : network_thread_(network_thread) {
+    : network_thread_(network_thread), use_dcsctp_("Enabled", false) {
   RTC_UNUSED(network_thread_);
+#ifdef WEBRTC_HAVE_DCSCTP
+  webrtc::ParseFieldTrial({&use_dcsctp_}, webrtc::field_trial::FindFullName(
+                                              "WebRTC-DataChannel-Dcsctp"));
+#endif
 }
 
 std::unique_ptr<SctpTransportInternal>
 SctpTransportFactory::CreateSctpTransport(
     rtc::PacketTransportInternal* transport) {
   std::unique_ptr<SctpTransportInternal> result;
+#ifdef WEBRTC_HAVE_DCSCTP
+  if (use_dcsctp_.Get()) {
+    result = std::unique_ptr<SctpTransportInternal>(new webrtc::DcSctpTransport(
+        network_thread_, transport, webrtc::Clock::GetRealTimeClock()));
+  }
+#endif
 #ifdef WEBRTC_HAVE_USRSCTP
   if (!result) {
     result = std::unique_ptr<SctpTransportInternal>(

media/sctp/sctp_transport_factory.h

@@ -15,6 +15,7 @@
 
 #include "api/transport/sctp_transport_factory_interface.h"
 #include "media/sctp/sctp_transport_internal.h"
+#include "rtc_base/experiments/field_trial_parser.h"
 #include "rtc_base/thread.h"
 
 namespace cricket {
@@ -28,6 +29,7 @@ class SctpTransportFactory : public webrtc::SctpTransportFactoryInterface {
 
  private:
   rtc::Thread* network_thread_;
+  webrtc::FieldTrialFlag use_dcsctp_;
 };
 
 }  // namespace cricket

pc/data_channel_integrationtest.cc

@@ -27,17 +27,19 @@
 #include "rtc_base/gunit.h"
 #include "rtc_base/ref_counted_object.h"
 #include "rtc_base/virtual_socket_server.h"
+#include "test/gtest.h"
 
 namespace webrtc {
 
 namespace {
 
-class DataChannelIntegrationTest
-    : public PeerConnectionIntegrationBaseTest,
-      public ::testing::WithParamInterface<SdpSemantics> {
+class DataChannelIntegrationTest : public PeerConnectionIntegrationBaseTest,
+                                   public ::testing::WithParamInterface<
+                                       std::tuple<SdpSemantics, std::string>> {
  protected:
   DataChannelIntegrationTest()
-      : PeerConnectionIntegrationBaseTest(GetParam()) {}
+      : PeerConnectionIntegrationBaseTest(std::get<0>(GetParam()),
+                                          std::get<1>(GetParam())) {}
 };
 
 GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(DataChannelIntegrationTest);
@@ -657,15 +659,19 @@ TEST_P(DataChannelIntegrationTest, QueuedPacketsGetDeliveredInUnReliableMode) {
   EXPECT_EQ(2u, callee()->data_observer()->received_message_count());
 }
 
-INSTANTIATE_TEST_SUITE_P(DataChannelIntegrationTest,
-                         DataChannelIntegrationTest,
-                         Values(SdpSemantics::kPlanB,
-                                SdpSemantics::kUnifiedPlan));
+INSTANTIATE_TEST_SUITE_P(
+    DataChannelIntegrationTest,
+    DataChannelIntegrationTest,
+    Combine(Values(SdpSemantics::kPlanB, SdpSemantics::kUnifiedPlan),
+            Values("WebRTC-DataChannel-Dcsctp/Enabled/",
+                   "WebRTC-DataChannel-Dcsctp/Disabled/")));
 
-INSTANTIATE_TEST_SUITE_P(DataChannelIntegrationTest,
-                         DataChannelIntegrationTestWithFakeClock,
-                         Values(SdpSemantics::kPlanB,
-                                SdpSemantics::kUnifiedPlan));
+INSTANTIATE_TEST_SUITE_P(
+    DataChannelIntegrationTest,
+    DataChannelIntegrationTestWithFakeClock,
+    Combine(Values(SdpSemantics::kPlanB, SdpSemantics::kUnifiedPlan),
+            Values("WebRTC-DataChannel-Dcsctp/Enabled/",
+                   "WebRTC-DataChannel-Dcsctp/Disabled/")));
 
 TEST_F(DataChannelIntegrationTestUnifiedPlan,
        EndToEndCallWithBundledSctpDataChannel) {

pc/test/integration_test_helpers.h

@@ -1330,12 +1330,17 @@ class MockIceTransportFactory : public IceTransportFactory {
 // of everything else (including "PeerConnectionFactory"s).
 class PeerConnectionIntegrationBaseTest : public ::testing::Test {
  public:
-  explicit PeerConnectionIntegrationBaseTest(SdpSemantics sdp_semantics)
+  PeerConnectionIntegrationBaseTest(
+      SdpSemantics sdp_semantics,
+      absl::optional<std::string> field_trials = absl::nullopt)
       : sdp_semantics_(sdp_semantics),
         ss_(new rtc::VirtualSocketServer()),
         fss_(new rtc::FirewallSocketServer(ss_.get())),
         network_thread_(new rtc::Thread(fss_.get())),
-        worker_thread_(rtc::Thread::Create()) {
+        worker_thread_(rtc::Thread::Create()),
+        field_trials_(field_trials.has_value()
+                          ? new test::ScopedFieldTrials(*field_trials)
+                          : nullptr) {
     network_thread_->SetName("PCNetworkThread", this);
     worker_thread_->SetName("PCWorkerThread", this);
     RTC_CHECK(network_thread_->Start());
@@ -1839,6 +1844,7 @@ class PeerConnectionIntegrationBaseTest : public ::testing::Test {
   std::vector<std::unique_ptr<cricket::TestTurnCustomizer>> turn_customizers_;
   std::unique_ptr<PeerConnectionIntegrationWrapper> caller_;
   std::unique_ptr<PeerConnectionIntegrationWrapper> callee_;
+  std::unique_ptr<test::ScopedFieldTrials> field_trials_;
 };
 
 }  // namespace webrtc

webrtc.gni

@@ -286,6 +286,9 @@ declare_args() {
 }
 
 declare_args() {
+  # Enable the dcsctp backend for DataChannels and related unittests
+  rtc_build_dcsctp = !build_with_mozilla && rtc_enable_sctp
+
   # Enable the usrsctp backend for DataChannels and related unittests
   rtc_build_usrsctp = !build_with_mozilla && rtc_enable_sctp
 }