Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 1282 insertions, 0 deletions

diff --git a/third_party/libwebrtc/media/sctp/OWNERS b/third_party/libwebrtc/media/sctp/OWNERS
new file mode 100644
index 0000000000..da2f0178a8
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/OWNERS
@@ -0,0 +1,3 @@
+boivie@webrtc.org
+deadbeef@webrtc.org
+orphis@webrtc.org
diff --git a/third_party/libwebrtc/media/sctp/dcsctp_transport.cc b/third_party/libwebrtc/media/sctp/dcsctp_transport.cc
new file mode 100644
index 0000000000..062360d251
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/dcsctp_transport.cc
@@ -0,0 +1,679 @@
+/*
+ *  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 <atomic>
+#include <cstdint>
+#include <limits>
+#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/dcsctp_socket_factory.h"
+#include "net/dcsctp/public/packet_observer.h"
+#include "net/dcsctp/public/text_pcap_packet_observer.h"
+#include "net/dcsctp/public/types.h"
+#include "p2p/base/packet_transport_internal.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/socket.h"
+#include "rtc_base/strings/string_builder.h"
+#include "rtc_base/thread.h"
+#include "rtc_base/trace_event.h"
+#include "system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+namespace {
+using ::dcsctp::SendPacketStatus;
+
+// When there is packet loss for a long time, the SCTP retry timers will use
+// exponential backoff, which can grow to very long durations and when the
+// connection recovers, it may take a long time to reach the new backoff
+// duration. By limiting it to a reasonable limit, the time to recover reduces.
+constexpr dcsctp::DurationMs kMaxTimerBackoffDuration =
+    dcsctp::DurationMs(3000);
+
+enum class WebrtcPPID : dcsctp::PPID::UnderlyingType {
+  // 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(DataMessageType message_type, size_t size) {
+  switch (message_type) {
+    case webrtc::DataMessageType::kControl:
+      return WebrtcPPID::kDCEP;
+    case webrtc::DataMessageType::kText:
+      return size > 0 ? WebrtcPPID::kString : WebrtcPPID::kStringEmpty;
+    case webrtc::DataMessageType::kBinary:
+      return size > 0 ? WebrtcPPID::kBinary : WebrtcPPID::kBinaryEmpty;
+  }
+}
+
+absl::optional<DataMessageType> ToDataMessageType(dcsctp::PPID ppid) {
+  switch (static_cast<WebrtcPPID>(ppid.value())) {
+    case WebrtcPPID::kDCEP:
+      return webrtc::DataMessageType::kControl;
+    case WebrtcPPID::kString:
+    case WebrtcPPID::kStringPartial:
+    case WebrtcPPID::kStringEmpty:
+      return webrtc::DataMessageType::kText;
+    case WebrtcPPID::kBinary:
+    case WebrtcPPID::kBinaryPartial:
+    case WebrtcPPID::kBinaryEmpty:
+      return webrtc::DataMessageType::kBinary;
+  }
+  return absl::nullopt;
+}
+
+absl::optional<cricket::SctpErrorCauseCode> ToErrorCauseCode(
+    dcsctp::ErrorKind error) {
+  switch (error) {
+    case dcsctp::ErrorKind::kParseFailed:
+      return cricket::SctpErrorCauseCode::kUnrecognizedParameters;
+    case dcsctp::ErrorKind::kPeerReported:
+      return cricket::SctpErrorCauseCode::kUserInitiatedAbort;
+    case dcsctp::ErrorKind::kWrongSequence:
+    case dcsctp::ErrorKind::kProtocolViolation:
+      return cricket::SctpErrorCauseCode::kProtocolViolation;
+    case dcsctp::ErrorKind::kResourceExhaustion:
+      return cricket::SctpErrorCauseCode::kOutOfResource;
+    case dcsctp::ErrorKind::kTooManyRetries:
+    case dcsctp::ErrorKind::kUnsupportedOperation:
+    case dcsctp::ErrorKind::kNoError:
+    case dcsctp::ErrorKind::kNotConnected:
+      // No SCTP error cause code matches those
+      break;
+  }
+  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)
+    : DcSctpTransport(network_thread,
+                      transport,
+                      clock,
+                      std::make_unique<dcsctp::DcSctpSocketFactory>()) {}
+
+DcSctpTransport::DcSctpTransport(
+    rtc::Thread* network_thread,
+    rtc::PacketTransportInternal* transport,
+    Clock* clock,
+    std::unique_ptr<dcsctp::DcSctpSocketFactory> socket_factory)
+    : network_thread_(network_thread),
+      transport_(transport),
+      clock_(clock),
+      random_(clock_->TimeInMicroseconds()),
+      socket_factory_(std::move(socket_factory)),
+      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 std::atomic<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::SetOnConnectedCallback(std::function<void()> callback) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  on_connected_callback_ = std::move(callback);
+}
+
+void DcSctpTransport::SetDataChannelSink(DataChannelSink* sink) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  data_channel_sink_ = sink;
+  if (data_channel_sink_ && ready_to_send_data_) {
+    data_channel_sink_->OnReadyToSend();
+  }
+}
+
+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_DLOG(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;
+    options.max_timer_backoff_duration = kMaxTimerBackoffDuration;
+    // Don't close the connection automatically on too many retransmissions.
+    options.max_retransmissions = absl::nullopt;
+    options.max_init_retransmits = absl::nullopt;
+
+    std::unique_ptr<dcsctp::PacketObserver> packet_observer;
+    if (RTC_LOG_CHECK_LEVEL(LS_VERBOSE)) {
+      packet_observer =
+          std::make_unique<dcsctp::TextPcapPacketObserver>(debug_name_);
+    }
+
+    socket_ = socket_factory_->Create(debug_name_, *this,
+                                      std::move(packet_observer), 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_DCHECK_RUN_ON(network_thread_);
+  RTC_DLOG(LS_INFO) << debug_name_ << "->OpenStream(" << sid << ").";
+
+  StreamState stream_state;
+  stream_states_.insert_or_assign(dcsctp::StreamID(static_cast<uint16_t>(sid)),
+                                  stream_state);
+  return true;
+}
+
+bool DcSctpTransport::ResetStream(int sid) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DLOG(LS_INFO) << debug_name_ << "->ResetStream(" << sid << ").";
+  if (!socket_) {
+    RTC_LOG(LS_ERROR) << debug_name_ << "->ResetStream(sid=" << sid
+                      << "): Transport is not started.";
+    return false;
+  }
+
+  dcsctp::StreamID streams[1] = {dcsctp::StreamID(static_cast<uint16_t>(sid))};
+
+  auto it = stream_states_.find(streams[0]);
+  if (it == stream_states_.end()) {
+    RTC_LOG(LS_ERROR) << debug_name_ << "->ResetStream(sid=" << sid
+                      << "): Stream is not open.";
+    return false;
+  }
+
+  StreamState& stream_state = it->second;
+  if (stream_state.closure_initiated || stream_state.incoming_reset_done ||
+      stream_state.outgoing_reset_done) {
+    // The closing procedure was already initiated by the remote, don't do
+    // anything.
+    return false;
+  }
+  stream_state.closure_initiated = true;
+  socket_->ResetStreams(streams);
+  return true;
+}
+
+bool DcSctpTransport::SendData(int sid,
+                               const SendDataParams& params,
+                               const rtc::CopyOnWriteBuffer& payload,
+                               cricket::SendDataResult* result) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DLOG(LS_VERBOSE) << debug_name_ << "->SendData(sid=" << sid
+                       << ", type=" << static_cast<int>(params.type)
+                       << ", length=" << payload.size() << ").";
+
+  if (!socket_) {
+    RTC_LOG(LS_ERROR) << debug_name_
+                      << "->SendData(...): Transport is not started.";
+    *result = cricket::SDR_ERROR;
+    return false;
+  }
+
+  // It is possible for a message to be sent from the signaling thread at the
+  // same time a data-channel is closing, but before the signaling thread is
+  // aware of it. So we need to keep track of currently active data channels and
+  // skip sending messages for the ones that are not open or closing.
+  // The sending errors are not impacting the data channel API contract as
+  // it is allowed to discard queued messages when the channel is closing.
+  auto stream_state =
+      stream_states_.find(dcsctp::StreamID(static_cast<uint16_t>(sid)));
+  if (stream_state == stream_states_.end()) {
+    RTC_LOG(LS_VERBOSE) << "Skipping message on non-open stream with sid: "
+                        << sid;
+    *result = cricket::SDR_ERROR;
+    return false;
+  }
+
+  if (stream_state->second.closure_initiated ||
+      stream_state->second.incoming_reset_done ||
+      stream_state->second.outgoing_reset_done) {
+    RTC_LOG(LS_VERBOSE) << "Skipping message on closing stream with sid: "
+                        << sid;
+    *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_WARNING) << 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>(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.has_value()) {
+    RTC_DCHECK(*params.max_rtx_ms >= 0 &&
+               *params.max_rtx_ms <= std::numeric_limits<uint16_t>::max());
+    send_options.lifetime = dcsctp::DurationMs(*params.max_rtx_ms);
+  }
+  if (params.max_rtx_count.has_value()) {
+    RTC_DCHECK(*params.max_rtx_count >= 0 &&
+               *params.max_rtx_count <= std::numeric_limits<uint16_t>::max());
+    send_options.max_retransmissions = *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;
+      break;
+  }
+
+  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;
+}
+
+SendPacketStatus DcSctpTransport::SendPacketWithStatus(
+    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 SendPacketStatus::kError;
+  }
+  TRACE_EVENT0("webrtc", "DcSctpTransport::SendPacket");
+
+  if (!transport_ || !transport_->writable())
+    return SendPacketStatus::kError;
+
+  RTC_DLOG(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_WARNING) << debug_name_ << "->SendPacket(length=" << data.size()
+                        << ") failed with error: " << transport_->GetError()
+                        << ".";
+
+    if (rtc::IsBlockingError(transport_->GetError())) {
+      return SendPacketStatus::kTemporaryFailure;
+    }
+    return SendPacketStatus::kError;
+  }
+  return SendPacketStatus::kSuccess;
+}
+
+std::unique_ptr<dcsctp::Timeout> DcSctpTransport::CreateTimeout(
+    webrtc::TaskQueueBase::DelayPrecision precision) {
+  return task_queue_timeout_factory_.CreateTimeout(precision);
+}
+
+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::OnTotalBufferedAmountLow() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (!ready_to_send_data_) {
+    ready_to_send_data_ = true;
+    if (data_channel_sink_) {
+      data_channel_sink_->OnReadyToSend();
+    }
+  }
+}
+
+void DcSctpTransport::OnMessageReceived(dcsctp::DcSctpMessage message) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DLOG(LS_VERBOSE) << 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());
+
+  if (data_channel_sink_) {
+    data_channel_sink_->OnDataReceived(
+        receive_data_params.sid, receive_data_params.type, receive_buffer_);
+  }
+}
+
+void DcSctpTransport::OnError(dcsctp::ErrorKind error,
+                              absl::string_view message) {
+  if (error == dcsctp::ErrorKind::kResourceExhaustion) {
+    // Indicates that a message failed to be enqueued, because the send buffer
+    // is full, which is a very common (and wanted) state for high throughput
+    // sending/benchmarks.
+    RTC_LOG(LS_VERBOSE) << debug_name_
+                        << "->OnError(error=" << dcsctp::ToString(error)
+                        << ", message=" << message << ").";
+  } else {
+    RTC_LOG(LS_ERROR) << debug_name_
+                      << "->OnError(error=" << dcsctp::ToString(error)
+                      << ", message=" << message << ").";
+  }
+}
+
+void DcSctpTransport::OnAborted(dcsctp::ErrorKind error,
+                                absl::string_view message) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_LOG(LS_ERROR) << debug_name_
+                    << "->OnAborted(error=" << dcsctp::ToString(error)
+                    << ", message=" << message << ").";
+  ready_to_send_data_ = false;
+  RTCError rtc_error(RTCErrorType::OPERATION_ERROR_WITH_DATA,
+                     std::string(message));
+  rtc_error.set_error_detail(RTCErrorDetailType::SCTP_FAILURE);
+  auto code = ToErrorCauseCode(error);
+  if (code.has_value()) {
+    rtc_error.set_sctp_cause_code(static_cast<uint16_t>(*code));
+  }
+  if (data_channel_sink_) {
+    data_channel_sink_->OnTransportClosed(rtc_error);
+  }
+}
+
+void DcSctpTransport::OnConnected() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  RTC_DLOG(LS_INFO) << debug_name_ << "->OnConnected().";
+  ready_to_send_data_ = true;
+  if (data_channel_sink_) {
+    data_channel_sink_->OnReadyToSend();
+  }
+  if (on_connected_callback_) {
+    on_connected_callback_();
+  }
+}
+
+void DcSctpTransport::OnClosed() {
+  RTC_DLOG(LS_INFO) << debug_name_ << "->OnClosed().";
+  ready_to_send_data_ = false;
+}
+
+void DcSctpTransport::OnConnectionRestarted() {
+  RTC_DLOG(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_WARNING)
+        << debug_name_
+        << "->OnStreamsResetFailed(...): Outgoing stream reset failed"
+        << ", sid=" << stream_id.value() << ", reason: " << reason << ".";
+  }
+}
+
+void DcSctpTransport::OnStreamsResetPerformed(
+    rtc::ArrayView<const dcsctp::StreamID> outgoing_streams) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  for (auto& stream_id : outgoing_streams) {
+    RTC_LOG(LS_INFO) << debug_name_
+                     << "->OnStreamsResetPerformed(...): Outgoing stream reset"
+                     << ", sid=" << stream_id.value();
+
+    auto it = stream_states_.find(stream_id);
+    if (it == stream_states_.end()) {
+      // Ignoring an outgoing stream reset for a closed stream
+      return;
+    }
+
+    StreamState& stream_state = it->second;
+    stream_state.outgoing_reset_done = true;
+
+    if (stream_state.incoming_reset_done) {
+      //  When the close was not initiated locally, we can signal the end of the
+      //  data channel close procedure when the remote ACKs the reset.
+      if (data_channel_sink_) {
+        data_channel_sink_->OnChannelClosed(stream_id.value());
+      }
+      stream_states_.erase(stream_id);
+    }
+  }
+}
+
+void DcSctpTransport::OnIncomingStreamsReset(
+    rtc::ArrayView<const dcsctp::StreamID> incoming_streams) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  for (auto& stream_id : incoming_streams) {
+    RTC_LOG(LS_INFO) << debug_name_
+                     << "->OnIncomingStreamsReset(...): Incoming stream reset"
+                     << ", sid=" << stream_id.value();
+
+    auto it = stream_states_.find(stream_id);
+    if (it == stream_states_.end())
+      return;
+
+    StreamState& stream_state = it->second;
+    stream_state.incoming_reset_done = true;
+
+    if (!stream_state.closure_initiated) {
+      // When receiving an incoming stream reset event for a non local close
+      // procedure, the transport needs to reset the stream in the other
+      // direction too.
+      dcsctp::StreamID streams[1] = {stream_id};
+      socket_->ResetStreams(streams);
+      if (data_channel_sink_) {
+        data_channel_sink_->OnChannelClosing(stream_id.value());
+      }
+    }
+
+    if (stream_state.outgoing_reset_done) {
+      // The close procedure that was initiated locally is complete when we
+      // receive and incoming reset event.
+      if (data_channel_sink_) {
+        data_channel_sink_->OnChannelClosed(stream_id.value());
+      }
+      stream_states_.erase(stream_id);
+    }
+  }
+}
+
+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_DLOG(LS_VERBOSE) << 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) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (flags) {
+    // We are only interested in SCTP packets.
+    return;
+  }
+
+  RTC_DLOG(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_DCHECK_RUN_ON(network_thread_);
+  RTC_DLOG(LS_VERBOSE) << debug_name_ << "->OnTransportClosed().";
+  if (data_channel_sink_) {
+    data_channel_sink_->OnTransportClosed({});
+  }
+}
+
+void DcSctpTransport::MaybeConnectSocket() {
+  if (transport_ && transport_->writable() && socket_ &&
+      socket_->state() == dcsctp::SocketState::kClosed) {
+    socket_->Connect();
+  }
+}
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/media/sctp/dcsctp_transport.h b/third_party/libwebrtc/media/sctp/dcsctp_transport.h
new file mode 100644
index 0000000000..f86ac5a23a
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/dcsctp_transport.h
@@ -0,0 +1,142 @@
+/*
+ *  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 "api/task_queue/task_queue_base.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/dcsctp_socket_factory.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/containers/flat_map.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 "rtc_base/thread_annotations.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(rtc::Thread* network_thread,
+                  rtc::PacketTransportInternal* transport,
+                  Clock* clock,
+                  std::unique_ptr<dcsctp::DcSctpSocketFactory> socket_factory);
+  ~DcSctpTransport() override;
+
+  // cricket::SctpTransportInternal
+  void SetOnConnectedCallback(std::function<void()> callback) override;
+  void SetDataChannelSink(DataChannelSink* sink) override;
+  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(int sid,
+                const 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
+  dcsctp::SendPacketStatus SendPacketWithStatus(
+      rtc::ArrayView<const uint8_t> data) override;
+  std::unique_ptr<dcsctp::Timeout> CreateTimeout(
+      webrtc::TaskQueueBase::DelayPrecision precision) override;
+  dcsctp::TimeMs TimeMillis() override;
+  uint32_t GetRandomInt(uint32_t low, uint32_t high) override;
+  void OnTotalBufferedAmountLow() 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_;
+
+  std::unique_ptr<dcsctp::DcSctpSocketFactory> socket_factory_;
+  dcsctp::TaskQueueTimeoutFactory task_queue_timeout_factory_;
+  std::unique_ptr<dcsctp::DcSctpSocketInterface> socket_;
+  std::string debug_name_ = "DcSctpTransport";
+  rtc::CopyOnWriteBuffer receive_buffer_;
+
+  // Used to keep track of the state of data channels.
+  // Reset needs to happen both ways before signaling the transport
+  // is closed.
+  struct StreamState {
+    // True when the local connection has initiated the reset.
+    // If a connection receives a reset for a stream that isn't
+    // already being reset locally, it needs to fire the signal
+    // SignalClosingProcedureStartedRemotely.
+    bool closure_initiated = false;
+    // True when the local connection received OnIncomingStreamsReset
+    bool incoming_reset_done = false;
+    // True when the local connection received OnStreamsResetPerformed
+    bool outgoing_reset_done = false;
+  };
+
+  // Map of all currently open or closing data channels
+  flat_map<dcsctp::StreamID, StreamState> stream_states_
+      RTC_GUARDED_BY(network_thread_);
+  bool ready_to_send_data_ = false;
+  std::function<void()> on_connected_callback_ RTC_GUARDED_BY(network_thread_);
+  DataChannelSink* data_channel_sink_ RTC_GUARDED_BY(network_thread_) = nullptr;
+};
+
+}  // namespace webrtc
+
+#endif  // MEDIA_SCTP_DCSCTP_TRANSPORT_H_
diff --git a/third_party/libwebrtc/media/sctp/dcsctp_transport_unittest.cc b/third_party/libwebrtc/media/sctp/dcsctp_transport_unittest.cc
new file mode 100644
index 0000000000..08dc2ec0b6
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/dcsctp_transport_unittest.cc
@@ -0,0 +1,233 @@
+/*
+ *  Copyright 2022 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 <memory>
+#include <utility>
+
+#include "net/dcsctp/public/mock_dcsctp_socket.h"
+#include "net/dcsctp/public/mock_dcsctp_socket_factory.h"
+#include "p2p/base/fake_packet_transport.h"
+#include "test/gtest.h"
+
+using ::testing::_;
+using ::testing::ByMove;
+using ::testing::DoAll;
+using ::testing::ElementsAre;
+using ::testing::InSequence;
+using ::testing::Invoke;
+using ::testing::NiceMock;
+using ::testing::Return;
+using ::testing::ReturnPointee;
+
+namespace webrtc {
+
+namespace {
+class MockDataChannelObserver : public DataChannelSink {
+ public:
+  MOCK_METHOD(void, OnConnected, ());
+
+  // DataChannelSink
+  MOCK_METHOD(void,
+              OnDataReceived,
+              (int, DataMessageType, const rtc::CopyOnWriteBuffer&));
+  MOCK_METHOD(void, OnChannelClosing, (int));
+  MOCK_METHOD(void, OnChannelClosed, (int));
+  MOCK_METHOD(void, OnReadyToSend, ());
+  MOCK_METHOD(void, OnTransportClosed, (RTCError));
+};
+
+class Peer {
+ public:
+  Peer() : fake_packet_transport_("transport"), simulated_clock_(1000) {
+    auto socket_ptr = std::make_unique<dcsctp::MockDcSctpSocket>();
+    socket_ = socket_ptr.get();
+
+    auto mock_dcsctp_socket_factory =
+        std::make_unique<dcsctp::MockDcSctpSocketFactory>();
+    EXPECT_CALL(*mock_dcsctp_socket_factory, Create)
+        .Times(1)
+        .WillOnce(Return(ByMove(std::move(socket_ptr))));
+
+    sctp_transport_ = std::make_unique<webrtc::DcSctpTransport>(
+        rtc::Thread::Current(), &fake_packet_transport_, &simulated_clock_,
+        std::move(mock_dcsctp_socket_factory));
+    sctp_transport_->SetDataChannelSink(&observer_);
+    sctp_transport_->SetOnConnectedCallback(
+        [this]() { observer_.OnConnected(); });
+  }
+
+  rtc::FakePacketTransport fake_packet_transport_;
+  webrtc::SimulatedClock simulated_clock_;
+  dcsctp::MockDcSctpSocket* socket_;
+  std::unique_ptr<webrtc::DcSctpTransport> sctp_transport_;
+  NiceMock<MockDataChannelObserver> observer_;
+};
+}  // namespace
+
+TEST(DcSctpTransportTest, OpenSequence) {
+  rtc::AutoThread main_thread;
+  Peer peer_a;
+  peer_a.fake_packet_transport_.SetWritable(true);
+
+  EXPECT_CALL(*peer_a.socket_, Connect)
+      .Times(1)
+      .WillOnce(Invoke(peer_a.sctp_transport_.get(),
+                       &dcsctp::DcSctpSocketCallbacks::OnConnected));
+  EXPECT_CALL(peer_a.observer_, OnReadyToSend);
+  EXPECT_CALL(peer_a.observer_, OnConnected);
+
+  peer_a.sctp_transport_->Start(5000, 5000, 256 * 1024);
+}
+
+// Tests that the close sequence invoked from one end results in the stream to
+// be reset from both ends and all the proper signals are sent.
+TEST(DcSctpTransportTest, CloseSequence) {
+  rtc::AutoThread main_thread;
+  Peer peer_a;
+  Peer peer_b;
+  peer_a.fake_packet_transport_.SetDestination(&peer_b.fake_packet_transport_,
+                                               false);
+  {
+    InSequence sequence;
+
+    EXPECT_CALL(*peer_a.socket_, ResetStreams(ElementsAre(dcsctp::StreamID(1))))
+        .WillOnce(Return(dcsctp::ResetStreamsStatus::kPerformed));
+
+    EXPECT_CALL(*peer_b.socket_, ResetStreams(ElementsAre(dcsctp::StreamID(1))))
+        .WillOnce(Return(dcsctp::ResetStreamsStatus::kPerformed));
+
+    EXPECT_CALL(peer_a.observer_, OnChannelClosing(1)).Times(0);
+    EXPECT_CALL(peer_b.observer_, OnChannelClosing(1));
+    EXPECT_CALL(peer_a.observer_, OnChannelClosed(1));
+    EXPECT_CALL(peer_b.observer_, OnChannelClosed(1));
+  }
+
+  peer_a.sctp_transport_->Start(5000, 5000, 256 * 1024);
+  peer_b.sctp_transport_->Start(5000, 5000, 256 * 1024);
+  peer_a.sctp_transport_->OpenStream(1);
+  peer_b.sctp_transport_->OpenStream(1);
+  peer_a.sctp_transport_->ResetStream(1);
+
+  // Simulate the callbacks from the stream resets
+  dcsctp::StreamID streams[1] = {dcsctp::StreamID(1)};
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_a.sctp_transport_.get())
+      ->OnStreamsResetPerformed(streams);
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_b.sctp_transport_.get())
+      ->OnIncomingStreamsReset(streams);
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_a.sctp_transport_.get())
+      ->OnIncomingStreamsReset(streams);
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_b.sctp_transport_.get())
+      ->OnStreamsResetPerformed(streams);
+}
+
+// Tests that the close sequence initiated from both peers at the same time
+// terminates properly. Both peers will think they initiated it, so no
+// OnClosingProcedureStartedRemotely should be called.
+TEST(DcSctpTransportTest, CloseSequenceSimultaneous) {
+  rtc::AutoThread main_thread;
+  Peer peer_a;
+  Peer peer_b;
+  peer_a.fake_packet_transport_.SetDestination(&peer_b.fake_packet_transport_,
+                                               false);
+  {
+    InSequence sequence;
+
+    EXPECT_CALL(*peer_a.socket_, ResetStreams(ElementsAre(dcsctp::StreamID(1))))
+        .WillOnce(Return(dcsctp::ResetStreamsStatus::kPerformed));
+
+    EXPECT_CALL(*peer_b.socket_, ResetStreams(ElementsAre(dcsctp::StreamID(1))))
+        .WillOnce(Return(dcsctp::ResetStreamsStatus::kPerformed));
+
+    EXPECT_CALL(peer_a.observer_, OnChannelClosing(1)).Times(0);
+    EXPECT_CALL(peer_b.observer_, OnChannelClosing(1)).Times(0);
+    EXPECT_CALL(peer_a.observer_, OnChannelClosed(1));
+    EXPECT_CALL(peer_b.observer_, OnChannelClosed(1));
+  }
+
+  peer_a.sctp_transport_->Start(5000, 5000, 256 * 1024);
+  peer_b.sctp_transport_->Start(5000, 5000, 256 * 1024);
+  peer_a.sctp_transport_->OpenStream(1);
+  peer_b.sctp_transport_->OpenStream(1);
+  peer_a.sctp_transport_->ResetStream(1);
+  peer_b.sctp_transport_->ResetStream(1);
+
+  // Simulate the callbacks from the stream resets
+  dcsctp::StreamID streams[1] = {dcsctp::StreamID(1)};
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_a.sctp_transport_.get())
+      ->OnStreamsResetPerformed(streams);
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_b.sctp_transport_.get())
+      ->OnStreamsResetPerformed(streams);
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_a.sctp_transport_.get())
+      ->OnIncomingStreamsReset(streams);
+  static_cast<dcsctp::DcSctpSocketCallbacks*>(peer_b.sctp_transport_.get())
+      ->OnIncomingStreamsReset(streams);
+}
+
+TEST(DcSctpTransportTest, DiscardMessageClosedChannel) {
+  rtc::AutoThread main_thread;
+  Peer peer_a;
+
+  EXPECT_CALL(*peer_a.socket_, Send(_, _)).Times(0);
+
+  peer_a.sctp_transport_->Start(5000, 5000, 256 * 1024);
+
+  cricket::SendDataResult result;
+  SendDataParams params;
+  rtc::CopyOnWriteBuffer payload;
+  bool send_data_return =
+      peer_a.sctp_transport_->SendData(1, params, payload, &result);
+  EXPECT_FALSE(send_data_return);
+  EXPECT_EQ(cricket::SDR_ERROR, result);
+}
+
+TEST(DcSctpTransportTest, DiscardMessageClosingChannel) {
+  rtc::AutoThread main_thread;
+  Peer peer_a;
+
+  EXPECT_CALL(*peer_a.socket_, Send(_, _)).Times(0);
+
+  peer_a.sctp_transport_->OpenStream(1);
+  peer_a.sctp_transport_->Start(5000, 5000, 256 * 1024);
+  peer_a.sctp_transport_->ResetStream(1);
+
+  cricket::SendDataResult result;
+  SendDataParams params;
+  rtc::CopyOnWriteBuffer payload;
+
+  bool send_data_return =
+      peer_a.sctp_transport_->SendData(1, params, payload, &result);
+  EXPECT_FALSE(send_data_return);
+  EXPECT_EQ(cricket::SDR_ERROR, result);
+}
+
+TEST(DcSctpTransportTest, SendDataOpenChannel) {
+  rtc::AutoThread main_thread;
+  Peer peer_a;
+  dcsctp::DcSctpOptions options;
+
+  EXPECT_CALL(*peer_a.socket_, Send(_, _)).Times(1);
+  EXPECT_CALL(*peer_a.socket_, options()).WillOnce(ReturnPointee(&options));
+
+  peer_a.sctp_transport_->OpenStream(1);
+  peer_a.sctp_transport_->Start(5000, 5000, 256 * 1024);
+
+  cricket::SendDataResult result;
+  SendDataParams params;
+  rtc::CopyOnWriteBuffer payload;
+
+  bool send_data_return =
+      peer_a.sctp_transport_->SendData(1, params, payload, &result);
+  EXPECT_TRUE(send_data_return);
+  EXPECT_EQ(cricket::SDR_SUCCESS, result);
+}
+
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/media/sctp/sctp_transport_factory.cc b/third_party/libwebrtc/media/sctp/sctp_transport_factory.cc
new file mode 100644
index 0000000000..457bc5f889
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/sctp_transport_factory.cc
@@ -0,0 +1,38 @@
+/*
+ *  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/sctp_transport_factory.h"
+
+#include "rtc_base/system/unused.h"
+
+#ifdef WEBRTC_HAVE_DCSCTP
+#include "media/sctp/dcsctp_transport.h"    // nogncheck
+#include "system_wrappers/include/clock.h"  // nogncheck
+#endif
+
+namespace cricket {
+
+SctpTransportFactory::SctpTransportFactory(rtc::Thread* network_thread)
+    : network_thread_(network_thread) {
+  RTC_UNUSED(network_thread_);
+}
+
+std::unique_ptr<SctpTransportInternal>
+SctpTransportFactory::CreateSctpTransport(
+    rtc::PacketTransportInternal* transport) {
+  std::unique_ptr<SctpTransportInternal> result;
+#ifdef WEBRTC_HAVE_DCSCTP
+  result = std::unique_ptr<SctpTransportInternal>(new webrtc::DcSctpTransport(
+      network_thread_, transport, webrtc::Clock::GetRealTimeClock()));
+#endif
+  return result;
+}
+
+}  // namespace cricket
diff --git a/third_party/libwebrtc/media/sctp/sctp_transport_factory.h b/third_party/libwebrtc/media/sctp/sctp_transport_factory.h
new file mode 100644
index 0000000000..4fff214129
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/sctp_transport_factory.h
@@ -0,0 +1,35 @@
+/*
+ *  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_SCTP_TRANSPORT_FACTORY_H_
+#define MEDIA_SCTP_SCTP_TRANSPORT_FACTORY_H_
+
+#include <memory>
+
+#include "api/transport/sctp_transport_factory_interface.h"
+#include "media/sctp/sctp_transport_internal.h"
+#include "rtc_base/thread.h"
+
+namespace cricket {
+
+class SctpTransportFactory : public webrtc::SctpTransportFactoryInterface {
+ public:
+  explicit SctpTransportFactory(rtc::Thread* network_thread);
+
+  std::unique_ptr<SctpTransportInternal> CreateSctpTransport(
+      rtc::PacketTransportInternal* transport) override;
+
+ private:
+  rtc::Thread* network_thread_;
+};
+
+}  // namespace cricket
+
+#endif  // MEDIA_SCTP_SCTP_TRANSPORT_FACTORY_H__
diff --git a/third_party/libwebrtc/media/sctp/sctp_transport_internal.h b/third_party/libwebrtc/media/sctp/sctp_transport_internal.h
new file mode 100644
index 0000000000..38da554911
--- /dev/null
+++ b/third_party/libwebrtc/media/sctp/sctp_transport_internal.h
@@ -0,0 +1,152 @@
+/*
+ *  Copyright (c) 2016 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_SCTP_TRANSPORT_INTERNAL_H_
+#define MEDIA_SCTP_SCTP_TRANSPORT_INTERNAL_H_
+
+// TODO(deadbeef): Move SCTP code out of media/, and make it not depend on
+// anything in media/.
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "api/transport/data_channel_transport_interface.h"
+// For SendDataParams/ReceiveDataParams.
+// TODO(deadbeef): Use something else for SCTP. It's confusing that we use an
+// SSRC field for SID.
+#include "media/base/media_channel.h"
+#include "p2p/base/packet_transport_internal.h"
+#include "rtc_base/copy_on_write_buffer.h"
+#include "rtc_base/thread.h"
+
+namespace cricket {
+
+// Constants that are important to API users
+// The size of the SCTP association send buffer. 256kB, the usrsctp default.
+constexpr int kSctpSendBufferSize = 256 * 1024;
+
+// The number of outgoing streams that we'll negotiate. Since stream IDs (SIDs)
+// are 0-based, the highest usable SID is 1023.
+//
+// It's recommended to use the maximum of 65535 in:
+// https://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-13#section-6.2
+// However, we use 1024 in order to save memory. usrsctp allocates 104 bytes
+// for each pair of incoming/outgoing streams (on a 64-bit system), so 65535
+// streams would waste ~6MB.
+//
+// Note: "max" and "min" here are inclusive.
+constexpr uint16_t kMaxSctpStreams = 1024;
+constexpr uint16_t kMaxSctpSid = kMaxSctpStreams - 1;
+constexpr uint16_t kMinSctpSid = 0;
+
+// This is the default SCTP port to use. It is passed along the wire and the
+// connectee and connector must be using the same port. It is not related to the
+// ports at the IP level. (Corresponds to: sockaddr_conn.sconn_port in
+// usrsctp.h)
+const int kSctpDefaultPort = 5000;
+
+// Error cause codes defined at
+// https://www.iana.org/assignments/sctp-parameters/sctp-parameters.xhtml#sctp-parameters-24
+enum class SctpErrorCauseCode : uint16_t {
+  kInvalidStreamIdentifier = 1,
+  kMissingMandatoryParameter = 2,
+  kStaleCookieError = 3,
+  kOutOfResource = 4,
+  kUnresolvableAddress = 5,
+  kUnrecognizedChunkType = 6,
+  kInvalidMandatoryParameter = 7,
+  kUnrecognizedParameters = 8,
+  kNoUserData = 9,
+  kCookieReceivedWhileShuttingDown = 10,
+  kRestartWithNewAddresses = 11,
+  kUserInitiatedAbort = 12,
+  kProtocolViolation = 13,
+};
+
+// Abstract SctpTransport interface for use internally (by PeerConnection etc.).
+// Exists to allow mock/fake SctpTransports to be created.
+class SctpTransportInternal {
+ public:
+  virtual ~SctpTransportInternal() {}
+
+  virtual void SetOnConnectedCallback(std::function<void()> callback) = 0;
+  virtual void SetDataChannelSink(webrtc::DataChannelSink* sink) = 0;
+
+  // Changes what underlying DTLS transport is uses. Used when switching which
+  // bundled transport the SctpTransport uses.
+  virtual void SetDtlsTransport(rtc::PacketTransportInternal* transport) = 0;
+
+  // When Start is called, connects as soon as possible; this can be called
+  // before DTLS completes, in which case the connection will begin when DTLS
+  // completes. This method can be called multiple times, though not if either
+  // of the ports are changed.
+  //
+  // `local_sctp_port` and `remote_sctp_port` are passed along the wire and the
+  // listener and connector must be using the same port. They are not related
+  // to the ports at the IP level. If set to -1, we default to
+  // kSctpDefaultPort.
+  // `max_message_size_` sets the max message size on the connection.
+  // It must be smaller than or equal to kSctpSendBufferSize.
+  // It can be changed by a secons Start() call.
+  //
+  // TODO(deadbeef): Support calling Start with different local/remote ports
+  // and create a new association? Not clear if this is something we need to
+  // support though. See: https://github.com/w3c/webrtc-pc/issues/979
+  virtual bool Start(int local_sctp_port,
+                     int remote_sctp_port,
+                     int max_message_size) = 0;
+
+  // NOTE: Initially there was a "Stop" method here, but it was never used, so
+  // it was removed.
+
+  // Informs SctpTransport that `sid` will start being used. Returns false if
+  // it is impossible to use `sid`, or if it's already in use.
+  // Until calling this, can't send data using `sid`.
+  // TODO(deadbeef): Actually implement the "returns false if `sid` can't be
+  // used" part. See:
+  // https://bugs.chromium.org/p/chromium/issues/detail?id=619849
+  virtual bool OpenStream(int sid) = 0;
+  // The inverse of OpenStream. Begins the closing procedure, which will
+  // eventually result in SignalClosingProcedureComplete on the side that
+  // initiates it, and both SignalClosingProcedureStartedRemotely and
+  // SignalClosingProcedureComplete on the other side.
+  virtual bool ResetStream(int sid) = 0;
+  // Send data down this channel (will be wrapped as SCTP packets then given to
+  // usrsctp that will then post the network interface).
+  // Returns true iff successful data somewhere on the send-queue/network.
+  // Uses `params.ssrc` as the SCTP sid.
+  virtual bool SendData(int sid,
+                        const webrtc::SendDataParams& params,
+                        const rtc::CopyOnWriteBuffer& payload,
+                        SendDataResult* result = nullptr) = 0;
+
+  // Indicates when the SCTP socket is created and not blocked by congestion
+  // control. This changes to false when SDR_BLOCK is returned from SendData,
+  // and
+  // changes to true when SignalReadyToSendData is fired. The underlying DTLS/
+  // ICE channels may be unwritable while ReadyToSendData is true, because data
+  // can still be queued in usrsctp.
+  virtual bool ReadyToSendData() = 0;
+  // Returns the current max message size, set with Start().
+  virtual int max_message_size() const = 0;
+  // Returns the current negotiated max # of outbound streams.
+  // Will return absl::nullopt if negotiation is incomplete.
+  virtual absl::optional<int> max_outbound_streams() const = 0;
+  // Returns the current negotiated max # of inbound streams.
+  virtual absl::optional<int> max_inbound_streams() const = 0;
+
+  // Helper for debugging.
+  virtual void set_debug_name_for_testing(const char* debug_name) = 0;
+};
+
+}  // namespace cricket
+
+#endif  // MEDIA_SCTP_SCTP_TRANSPORT_INTERNAL_H_