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-rw-r--r--third_party/libwebrtc/net/dcsctp/socket/dcsctp_socket.cc1781
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diff --git a/third_party/libwebrtc/net/dcsctp/socket/dcsctp_socket.cc b/third_party/libwebrtc/net/dcsctp/socket/dcsctp_socket.cc
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index 0000000000..f831ba090c
--- /dev/null
+++ b/third_party/libwebrtc/net/dcsctp/socket/dcsctp_socket.cc
@@ -0,0 +1,1781 @@
+/*
+ * 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.
+ */
+#include "net/dcsctp/socket/dcsctp_socket.h"
+
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "absl/functional/bind_front.h"
+#include "absl/memory/memory.h"
+#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 "net/dcsctp/packet/chunk/abort_chunk.h"
+#include "net/dcsctp/packet/chunk/chunk.h"
+#include "net/dcsctp/packet/chunk/cookie_ack_chunk.h"
+#include "net/dcsctp/packet/chunk/cookie_echo_chunk.h"
+#include "net/dcsctp/packet/chunk/data_chunk.h"
+#include "net/dcsctp/packet/chunk/data_common.h"
+#include "net/dcsctp/packet/chunk/error_chunk.h"
+#include "net/dcsctp/packet/chunk/forward_tsn_chunk.h"
+#include "net/dcsctp/packet/chunk/forward_tsn_common.h"
+#include "net/dcsctp/packet/chunk/heartbeat_ack_chunk.h"
+#include "net/dcsctp/packet/chunk/heartbeat_request_chunk.h"
+#include "net/dcsctp/packet/chunk/idata_chunk.h"
+#include "net/dcsctp/packet/chunk/iforward_tsn_chunk.h"
+#include "net/dcsctp/packet/chunk/init_ack_chunk.h"
+#include "net/dcsctp/packet/chunk/init_chunk.h"
+#include "net/dcsctp/packet/chunk/reconfig_chunk.h"
+#include "net/dcsctp/packet/chunk/sack_chunk.h"
+#include "net/dcsctp/packet/chunk/shutdown_ack_chunk.h"
+#include "net/dcsctp/packet/chunk/shutdown_chunk.h"
+#include "net/dcsctp/packet/chunk/shutdown_complete_chunk.h"
+#include "net/dcsctp/packet/chunk_validators.h"
+#include "net/dcsctp/packet/data.h"
+#include "net/dcsctp/packet/error_cause/cookie_received_while_shutting_down_cause.h"
+#include "net/dcsctp/packet/error_cause/error_cause.h"
+#include "net/dcsctp/packet/error_cause/no_user_data_cause.h"
+#include "net/dcsctp/packet/error_cause/out_of_resource_error_cause.h"
+#include "net/dcsctp/packet/error_cause/protocol_violation_cause.h"
+#include "net/dcsctp/packet/error_cause/unrecognized_chunk_type_cause.h"
+#include "net/dcsctp/packet/error_cause/user_initiated_abort_cause.h"
+#include "net/dcsctp/packet/parameter/forward_tsn_supported_parameter.h"
+#include "net/dcsctp/packet/parameter/parameter.h"
+#include "net/dcsctp/packet/parameter/state_cookie_parameter.h"
+#include "net/dcsctp/packet/parameter/supported_extensions_parameter.h"
+#include "net/dcsctp/packet/sctp_packet.h"
+#include "net/dcsctp/packet/tlv_trait.h"
+#include "net/dcsctp/public/dcsctp_message.h"
+#include "net/dcsctp/public/dcsctp_options.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+#include "net/dcsctp/public/packet_observer.h"
+#include "net/dcsctp/public/types.h"
+#include "net/dcsctp/rx/data_tracker.h"
+#include "net/dcsctp/rx/reassembly_queue.h"
+#include "net/dcsctp/socket/callback_deferrer.h"
+#include "net/dcsctp/socket/capabilities.h"
+#include "net/dcsctp/socket/heartbeat_handler.h"
+#include "net/dcsctp/socket/state_cookie.h"
+#include "net/dcsctp/socket/stream_reset_handler.h"
+#include "net/dcsctp/socket/transmission_control_block.h"
+#include "net/dcsctp/timer/timer.h"
+#include "net/dcsctp/tx/retransmission_queue.h"
+#include "net/dcsctp/tx/send_queue.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/strings/string_builder.h"
+#include "rtc_base/strings/string_format.h"
+
+namespace dcsctp {
+namespace {
+
+// https://tools.ietf.org/html/rfc4960#section-5.1
+constexpr uint32_t kMinVerificationTag = 1;
+constexpr uint32_t kMaxVerificationTag = std::numeric_limits<uint32_t>::max();
+
+// https://tools.ietf.org/html/rfc4960#section-3.3.2
+constexpr uint32_t kMinInitialTsn = 0;
+constexpr uint32_t kMaxInitialTsn = std::numeric_limits<uint32_t>::max();
+
+Capabilities ComputeCapabilities(const DcSctpOptions& options,
+ uint16_t peer_nbr_outbound_streams,
+ uint16_t peer_nbr_inbound_streams,
+ const Parameters& parameters) {
+ Capabilities capabilities;
+ absl::optional<SupportedExtensionsParameter> supported_extensions =
+ parameters.get<SupportedExtensionsParameter>();
+
+ if (options.enable_partial_reliability) {
+ capabilities.partial_reliability =
+ parameters.get<ForwardTsnSupportedParameter>().has_value();
+ if (supported_extensions.has_value()) {
+ capabilities.partial_reliability |=
+ supported_extensions->supports(ForwardTsnChunk::kType);
+ }
+ }
+
+ if (options.enable_message_interleaving && supported_extensions.has_value()) {
+ capabilities.message_interleaving =
+ supported_extensions->supports(IDataChunk::kType) &&
+ supported_extensions->supports(IForwardTsnChunk::kType);
+ }
+ if (supported_extensions.has_value() &&
+ supported_extensions->supports(ReConfigChunk::kType)) {
+ capabilities.reconfig = true;
+ }
+
+ capabilities.negotiated_maximum_incoming_streams = std::min(
+ options.announced_maximum_incoming_streams, peer_nbr_outbound_streams);
+ capabilities.negotiated_maximum_outgoing_streams = std::min(
+ options.announced_maximum_outgoing_streams, peer_nbr_inbound_streams);
+
+ return capabilities;
+}
+
+void AddCapabilityParameters(const DcSctpOptions& options,
+ Parameters::Builder& builder) {
+ std::vector<uint8_t> chunk_types = {ReConfigChunk::kType};
+
+ if (options.enable_partial_reliability) {
+ builder.Add(ForwardTsnSupportedParameter());
+ chunk_types.push_back(ForwardTsnChunk::kType);
+ }
+ if (options.enable_message_interleaving) {
+ chunk_types.push_back(IDataChunk::kType);
+ chunk_types.push_back(IForwardTsnChunk::kType);
+ }
+ builder.Add(SupportedExtensionsParameter(std::move(chunk_types)));
+}
+
+TieTag MakeTieTag(DcSctpSocketCallbacks& cb) {
+ uint32_t tie_tag_upper =
+ cb.GetRandomInt(0, std::numeric_limits<uint32_t>::max());
+ uint32_t tie_tag_lower =
+ cb.GetRandomInt(1, std::numeric_limits<uint32_t>::max());
+ return TieTag(static_cast<uint64_t>(tie_tag_upper) << 32 |
+ static_cast<uint64_t>(tie_tag_lower));
+}
+
+SctpImplementation DeterminePeerImplementation(
+ rtc::ArrayView<const uint8_t> cookie) {
+ if (cookie.size() > 8) {
+ absl::string_view magic(reinterpret_cast<const char*>(cookie.data()), 8);
+ if (magic == "dcSCTP00") {
+ return SctpImplementation::kDcsctp;
+ }
+ if (magic == "KAME-BSD") {
+ return SctpImplementation::kUsrSctp;
+ }
+ }
+ return SctpImplementation::kOther;
+}
+} // namespace
+
+DcSctpSocket::DcSctpSocket(absl::string_view log_prefix,
+ DcSctpSocketCallbacks& callbacks,
+ std::unique_ptr<PacketObserver> packet_observer,
+ const DcSctpOptions& options)
+ : log_prefix_(std::string(log_prefix) + ": "),
+ packet_observer_(std::move(packet_observer)),
+ options_(options),
+ callbacks_(callbacks),
+ timer_manager_([this](webrtc::TaskQueueBase::DelayPrecision precision) {
+ return callbacks_.CreateTimeout(precision);
+ }),
+ t1_init_(timer_manager_.CreateTimer(
+ "t1-init",
+ absl::bind_front(&DcSctpSocket::OnInitTimerExpiry, this),
+ TimerOptions(options.t1_init_timeout,
+ TimerBackoffAlgorithm::kExponential,
+ options.max_init_retransmits))),
+ t1_cookie_(timer_manager_.CreateTimer(
+ "t1-cookie",
+ absl::bind_front(&DcSctpSocket::OnCookieTimerExpiry, this),
+ TimerOptions(options.t1_cookie_timeout,
+ TimerBackoffAlgorithm::kExponential,
+ options.max_init_retransmits))),
+ t2_shutdown_(timer_manager_.CreateTimer(
+ "t2-shutdown",
+ absl::bind_front(&DcSctpSocket::OnShutdownTimerExpiry, this),
+ TimerOptions(options.t2_shutdown_timeout,
+ TimerBackoffAlgorithm::kExponential,
+ options.max_retransmissions))),
+ packet_sender_(callbacks_,
+ absl::bind_front(&DcSctpSocket::OnSentPacket, this)),
+ send_queue_(log_prefix_,
+ &callbacks_,
+ options_.max_send_buffer_size,
+ options_.mtu,
+ options_.default_stream_priority,
+ options_.total_buffered_amount_low_threshold) {}
+
+std::string DcSctpSocket::log_prefix() const {
+ return log_prefix_ + "[" + std::string(ToString(state_)) + "] ";
+}
+
+bool DcSctpSocket::IsConsistent() const {
+ if (tcb_ != nullptr && tcb_->reassembly_queue().HasMessages()) {
+ return false;
+ }
+ switch (state_) {
+ case State::kClosed:
+ return (tcb_ == nullptr && !t1_init_->is_running() &&
+ !t1_cookie_->is_running() && !t2_shutdown_->is_running());
+ case State::kCookieWait:
+ return (tcb_ == nullptr && t1_init_->is_running() &&
+ !t1_cookie_->is_running() && !t2_shutdown_->is_running());
+ case State::kCookieEchoed:
+ return (tcb_ != nullptr && !t1_init_->is_running() &&
+ t1_cookie_->is_running() && !t2_shutdown_->is_running() &&
+ tcb_->has_cookie_echo_chunk());
+ case State::kEstablished:
+ return (tcb_ != nullptr && !t1_init_->is_running() &&
+ !t1_cookie_->is_running() && !t2_shutdown_->is_running());
+ case State::kShutdownPending:
+ return (tcb_ != nullptr && !t1_init_->is_running() &&
+ !t1_cookie_->is_running() && !t2_shutdown_->is_running());
+ case State::kShutdownSent:
+ return (tcb_ != nullptr && !t1_init_->is_running() &&
+ !t1_cookie_->is_running() && t2_shutdown_->is_running());
+ case State::kShutdownReceived:
+ return (tcb_ != nullptr && !t1_init_->is_running() &&
+ !t1_cookie_->is_running() && !t2_shutdown_->is_running());
+ case State::kShutdownAckSent:
+ return (tcb_ != nullptr && !t1_init_->is_running() &&
+ !t1_cookie_->is_running() && t2_shutdown_->is_running());
+ }
+}
+
+constexpr absl::string_view DcSctpSocket::ToString(DcSctpSocket::State state) {
+ switch (state) {
+ case DcSctpSocket::State::kClosed:
+ return "CLOSED";
+ case DcSctpSocket::State::kCookieWait:
+ return "COOKIE_WAIT";
+ case DcSctpSocket::State::kCookieEchoed:
+ return "COOKIE_ECHOED";
+ case DcSctpSocket::State::kEstablished:
+ return "ESTABLISHED";
+ case DcSctpSocket::State::kShutdownPending:
+ return "SHUTDOWN_PENDING";
+ case DcSctpSocket::State::kShutdownSent:
+ return "SHUTDOWN_SENT";
+ case DcSctpSocket::State::kShutdownReceived:
+ return "SHUTDOWN_RECEIVED";
+ case DcSctpSocket::State::kShutdownAckSent:
+ return "SHUTDOWN_ACK_SENT";
+ }
+}
+
+void DcSctpSocket::SetState(State state, absl::string_view reason) {
+ if (state_ != state) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix_ << "Socket state changed from "
+ << ToString(state_) << " to " << ToString(state)
+ << " due to " << reason;
+ state_ = state;
+ }
+}
+
+void DcSctpSocket::SendInit() {
+ Parameters::Builder params_builder;
+ AddCapabilityParameters(options_, params_builder);
+ InitChunk init(/*initiate_tag=*/connect_params_.verification_tag,
+ /*a_rwnd=*/options_.max_receiver_window_buffer_size,
+ options_.announced_maximum_outgoing_streams,
+ options_.announced_maximum_incoming_streams,
+ connect_params_.initial_tsn, params_builder.Build());
+ SctpPacket::Builder b(VerificationTag(0), options_);
+ b.Add(init);
+ packet_sender_.Send(b);
+}
+
+void DcSctpSocket::MakeConnectionParameters() {
+ VerificationTag new_verification_tag(
+ callbacks_.GetRandomInt(kMinVerificationTag, kMaxVerificationTag));
+ TSN initial_tsn(callbacks_.GetRandomInt(kMinInitialTsn, kMaxInitialTsn));
+ connect_params_.initial_tsn = initial_tsn;
+ connect_params_.verification_tag = new_verification_tag;
+}
+
+void DcSctpSocket::Connect() {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ if (state_ == State::kClosed) {
+ MakeConnectionParameters();
+ RTC_DLOG(LS_INFO)
+ << log_prefix()
+ << rtc::StringFormat(
+ "Connecting. my_verification_tag=%08x, my_initial_tsn=%u",
+ *connect_params_.verification_tag, *connect_params_.initial_tsn);
+ SendInit();
+ t1_init_->Start();
+ SetState(State::kCookieWait, "Connect called");
+ } else {
+ RTC_DLOG(LS_WARNING) << log_prefix()
+ << "Called Connect on a socket that is not closed";
+ }
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::CreateTransmissionControlBlock(
+ const Capabilities& capabilities,
+ VerificationTag my_verification_tag,
+ TSN my_initial_tsn,
+ VerificationTag peer_verification_tag,
+ TSN peer_initial_tsn,
+ size_t a_rwnd,
+ TieTag tie_tag) {
+ metrics_.uses_message_interleaving = capabilities.message_interleaving;
+ metrics_.negotiated_maximum_incoming_streams =
+ capabilities.negotiated_maximum_incoming_streams;
+ metrics_.negotiated_maximum_outgoing_streams =
+ capabilities.negotiated_maximum_outgoing_streams;
+ tcb_ = std::make_unique<TransmissionControlBlock>(
+ timer_manager_, log_prefix_, options_, capabilities, callbacks_,
+ send_queue_, my_verification_tag, my_initial_tsn, peer_verification_tag,
+ peer_initial_tsn, a_rwnd, tie_tag, packet_sender_,
+ [this]() { return state_ == State::kEstablished; });
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Created TCB: " << tcb_->ToString();
+}
+
+void DcSctpSocket::RestoreFromState(const DcSctpSocketHandoverState& state) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ if (state_ != State::kClosed) {
+ callbacks_.OnError(ErrorKind::kUnsupportedOperation,
+ "Only closed socket can be restored from state");
+ } else {
+ if (state.socket_state ==
+ DcSctpSocketHandoverState::SocketState::kConnected) {
+ VerificationTag my_verification_tag =
+ VerificationTag(state.my_verification_tag);
+ connect_params_.verification_tag = my_verification_tag;
+
+ Capabilities capabilities;
+ capabilities.partial_reliability = state.capabilities.partial_reliability;
+ capabilities.message_interleaving =
+ state.capabilities.message_interleaving;
+ capabilities.reconfig = state.capabilities.reconfig;
+ capabilities.negotiated_maximum_incoming_streams =
+ state.capabilities.negotiated_maximum_incoming_streams;
+ capabilities.negotiated_maximum_outgoing_streams =
+ state.capabilities.negotiated_maximum_outgoing_streams;
+
+ send_queue_.RestoreFromState(state);
+
+ CreateTransmissionControlBlock(
+ capabilities, my_verification_tag, TSN(state.my_initial_tsn),
+ VerificationTag(state.peer_verification_tag),
+ TSN(state.peer_initial_tsn), static_cast<size_t>(0),
+ TieTag(state.tie_tag));
+
+ tcb_->RestoreFromState(state);
+
+ SetState(State::kEstablished, "restored from handover state");
+ callbacks_.OnConnected();
+ }
+ }
+
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::Shutdown() {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ if (tcb_ != nullptr) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "Upon receipt of the SHUTDOWN primitive from its upper layer, the
+ // endpoint enters the SHUTDOWN-PENDING state and remains there until all
+ // outstanding data has been acknowledged by its peer."
+
+ // TODO(webrtc:12739): Remove this check, as it just hides the problem that
+ // the socket can transition from ShutdownSent to ShutdownPending, or
+ // ShutdownAckSent to ShutdownPending which is illegal.
+ if (state_ != State::kShutdownSent && state_ != State::kShutdownAckSent) {
+ SetState(State::kShutdownPending, "Shutdown called");
+ t1_init_->Stop();
+ t1_cookie_->Stop();
+ MaybeSendShutdownOrAck();
+ }
+ } else {
+ // Connection closed before even starting to connect, or during the initial
+ // connection phase. There is no outstanding data, so the socket can just
+ // be closed (stopping any connection timers, if any), as this is the
+ // client's intention, by calling Shutdown.
+ InternalClose(ErrorKind::kNoError, "");
+ }
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::Close() {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ if (state_ != State::kClosed) {
+ if (tcb_ != nullptr) {
+ SctpPacket::Builder b = tcb_->PacketBuilder();
+ b.Add(AbortChunk(/*filled_in_verification_tag=*/true,
+ Parameters::Builder()
+ .Add(UserInitiatedAbortCause("Close called"))
+ .Build()));
+ packet_sender_.Send(b);
+ }
+ InternalClose(ErrorKind::kNoError, "");
+ } else {
+ RTC_DLOG(LS_INFO) << log_prefix() << "Called Close on a closed socket";
+ }
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::CloseConnectionBecauseOfTooManyTransmissionErrors() {
+ packet_sender_.Send(tcb_->PacketBuilder().Add(AbortChunk(
+ true, Parameters::Builder()
+ .Add(UserInitiatedAbortCause("Too many retransmissions"))
+ .Build())));
+ InternalClose(ErrorKind::kTooManyRetries, "Too many retransmissions");
+}
+
+void DcSctpSocket::InternalClose(ErrorKind error, absl::string_view message) {
+ if (state_ != State::kClosed) {
+ t1_init_->Stop();
+ t1_cookie_->Stop();
+ t2_shutdown_->Stop();
+ tcb_ = nullptr;
+
+ if (error == ErrorKind::kNoError) {
+ callbacks_.OnClosed();
+ } else {
+ callbacks_.OnAborted(error, message);
+ }
+ SetState(State::kClosed, message);
+ }
+ // This method's purpose is to abort/close and make it consistent by ensuring
+ // that e.g. all timers really are stopped.
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::SetStreamPriority(StreamID stream_id,
+ StreamPriority priority) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ send_queue_.SetStreamPriority(stream_id, priority);
+}
+StreamPriority DcSctpSocket::GetStreamPriority(StreamID stream_id) const {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ return send_queue_.GetStreamPriority(stream_id);
+}
+
+SendStatus DcSctpSocket::Send(DcSctpMessage message,
+ const SendOptions& send_options) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+ LifecycleId lifecycle_id = send_options.lifecycle_id;
+
+ if (message.payload().empty()) {
+ if (lifecycle_id.IsSet()) {
+ callbacks_.OnLifecycleEnd(lifecycle_id);
+ }
+ callbacks_.OnError(ErrorKind::kProtocolViolation,
+ "Unable to send empty message");
+ return SendStatus::kErrorMessageEmpty;
+ }
+ if (message.payload().size() > options_.max_message_size) {
+ if (lifecycle_id.IsSet()) {
+ callbacks_.OnLifecycleEnd(lifecycle_id);
+ }
+ callbacks_.OnError(ErrorKind::kProtocolViolation,
+ "Unable to send too large message");
+ return SendStatus::kErrorMessageTooLarge;
+ }
+ if (state_ == State::kShutdownPending || state_ == State::kShutdownSent ||
+ state_ == State::kShutdownReceived || state_ == State::kShutdownAckSent) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "An endpoint should reject any new data request from its upper layer
+ // if it is in the SHUTDOWN-PENDING, SHUTDOWN-SENT, SHUTDOWN-RECEIVED, or
+ // SHUTDOWN-ACK-SENT state."
+ if (lifecycle_id.IsSet()) {
+ callbacks_.OnLifecycleEnd(lifecycle_id);
+ }
+ callbacks_.OnError(ErrorKind::kWrongSequence,
+ "Unable to send message as the socket is shutting down");
+ return SendStatus::kErrorShuttingDown;
+ }
+ if (send_queue_.IsFull()) {
+ if (lifecycle_id.IsSet()) {
+ callbacks_.OnLifecycleEnd(lifecycle_id);
+ }
+ callbacks_.OnError(ErrorKind::kResourceExhaustion,
+ "Unable to send message as the send queue is full");
+ return SendStatus::kErrorResourceExhaustion;
+ }
+
+ TimeMs now = callbacks_.TimeMillis();
+ ++metrics_.tx_messages_count;
+ send_queue_.Add(now, std::move(message), send_options);
+ if (tcb_ != nullptr) {
+ tcb_->SendBufferedPackets(now);
+ }
+
+ RTC_DCHECK(IsConsistent());
+ return SendStatus::kSuccess;
+}
+
+ResetStreamsStatus DcSctpSocket::ResetStreams(
+ rtc::ArrayView<const StreamID> outgoing_streams) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ if (tcb_ == nullptr) {
+ callbacks_.OnError(ErrorKind::kWrongSequence,
+ "Can't reset streams as the socket is not connected");
+ return ResetStreamsStatus::kNotConnected;
+ }
+ if (!tcb_->capabilities().reconfig) {
+ callbacks_.OnError(ErrorKind::kUnsupportedOperation,
+ "Can't reset streams as the peer doesn't support it");
+ return ResetStreamsStatus::kNotSupported;
+ }
+
+ tcb_->stream_reset_handler().ResetStreams(outgoing_streams);
+ MaybeSendResetStreamsRequest();
+
+ RTC_DCHECK(IsConsistent());
+ return ResetStreamsStatus::kPerformed;
+}
+
+SocketState DcSctpSocket::state() const {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ switch (state_) {
+ case State::kClosed:
+ return SocketState::kClosed;
+ case State::kCookieWait:
+ case State::kCookieEchoed:
+ return SocketState::kConnecting;
+ case State::kEstablished:
+ return SocketState::kConnected;
+ case State::kShutdownPending:
+ case State::kShutdownSent:
+ case State::kShutdownReceived:
+ case State::kShutdownAckSent:
+ return SocketState::kShuttingDown;
+ }
+}
+
+void DcSctpSocket::SetMaxMessageSize(size_t max_message_size) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ options_.max_message_size = max_message_size;
+}
+
+size_t DcSctpSocket::buffered_amount(StreamID stream_id) const {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ return send_queue_.buffered_amount(stream_id);
+}
+
+size_t DcSctpSocket::buffered_amount_low_threshold(StreamID stream_id) const {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ return send_queue_.buffered_amount_low_threshold(stream_id);
+}
+
+void DcSctpSocket::SetBufferedAmountLowThreshold(StreamID stream_id,
+ size_t bytes) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ send_queue_.SetBufferedAmountLowThreshold(stream_id, bytes);
+}
+
+absl::optional<Metrics> DcSctpSocket::GetMetrics() const {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+
+ if (tcb_ == nullptr) {
+ return absl::nullopt;
+ }
+
+ Metrics metrics = metrics_;
+ metrics.cwnd_bytes = tcb_->cwnd();
+ metrics.srtt_ms = tcb_->current_srtt().value();
+ size_t packet_payload_size =
+ options_.mtu - SctpPacket::kHeaderSize - DataChunk::kHeaderSize;
+ metrics.unack_data_count =
+ tcb_->retransmission_queue().outstanding_items() +
+ (send_queue_.total_buffered_amount() + packet_payload_size - 1) /
+ packet_payload_size;
+ metrics.peer_rwnd_bytes = tcb_->retransmission_queue().rwnd();
+ metrics.negotiated_maximum_incoming_streams =
+ tcb_->capabilities().negotiated_maximum_incoming_streams;
+ metrics.negotiated_maximum_incoming_streams =
+ tcb_->capabilities().negotiated_maximum_incoming_streams;
+
+ return metrics;
+}
+
+void DcSctpSocket::MaybeSendShutdownOnPacketReceived(const SctpPacket& packet) {
+ if (state_ == State::kShutdownSent) {
+ bool has_data_chunk =
+ std::find_if(packet.descriptors().begin(), packet.descriptors().end(),
+ [](const SctpPacket::ChunkDescriptor& descriptor) {
+ return descriptor.type == DataChunk::kType;
+ }) != packet.descriptors().end();
+ if (has_data_chunk) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "While in the SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
+ // respond to each received packet containing one or more DATA chunks with
+ // a SHUTDOWN chunk and restart the T2-shutdown timer.""
+ SendShutdown();
+ t2_shutdown_->set_duration(tcb_->current_rto());
+ t2_shutdown_->Start();
+ }
+ }
+}
+
+void DcSctpSocket::MaybeSendResetStreamsRequest() {
+ absl::optional<ReConfigChunk> reconfig =
+ tcb_->stream_reset_handler().MakeStreamResetRequest();
+ if (reconfig.has_value()) {
+ SctpPacket::Builder builder = tcb_->PacketBuilder();
+ builder.Add(*reconfig);
+ packet_sender_.Send(builder);
+ }
+}
+
+bool DcSctpSocket::ValidatePacket(const SctpPacket& packet) {
+ const CommonHeader& header = packet.common_header();
+ VerificationTag my_verification_tag =
+ tcb_ != nullptr ? tcb_->my_verification_tag() : VerificationTag(0);
+
+ if (header.verification_tag == VerificationTag(0)) {
+ if (packet.descriptors().size() == 1 &&
+ packet.descriptors()[0].type == InitChunk::kType) {
+ // https://tools.ietf.org/html/rfc4960#section-8.5.1
+ // "When an endpoint receives an SCTP packet with the Verification Tag
+ // set to 0, it should verify that the packet contains only an INIT chunk.
+ // Otherwise, the receiver MUST silently discard the packet.""
+ return true;
+ }
+ callbacks_.OnError(
+ ErrorKind::kParseFailed,
+ "Only a single INIT chunk can be present in packets sent on "
+ "verification_tag = 0");
+ return false;
+ }
+
+ if (packet.descriptors().size() == 1 &&
+ packet.descriptors()[0].type == AbortChunk::kType) {
+ // https://tools.ietf.org/html/rfc4960#section-8.5.1
+ // "The receiver of an ABORT MUST accept the packet if the Verification
+ // Tag field of the packet matches its own tag and the T bit is not set OR
+ // if it is set to its peer's tag and the T bit is set in the Chunk Flags.
+ // Otherwise, the receiver MUST silently discard the packet and take no
+ // further action."
+ bool t_bit = (packet.descriptors()[0].flags & 0x01) != 0;
+ if (t_bit && tcb_ == nullptr) {
+ // Can't verify the tag - assume it's okey.
+ return true;
+ }
+ if ((!t_bit && header.verification_tag == my_verification_tag) ||
+ (t_bit && header.verification_tag == tcb_->peer_verification_tag())) {
+ return true;
+ }
+ callbacks_.OnError(ErrorKind::kParseFailed,
+ "ABORT chunk verification tag was wrong");
+ return false;
+ }
+
+ if (packet.descriptors()[0].type == InitAckChunk::kType) {
+ if (header.verification_tag == connect_params_.verification_tag) {
+ return true;
+ }
+ callbacks_.OnError(
+ ErrorKind::kParseFailed,
+ rtc::StringFormat(
+ "Packet has invalid verification tag: %08x, expected %08x",
+ *header.verification_tag, *connect_params_.verification_tag));
+ return false;
+ }
+
+ if (packet.descriptors()[0].type == CookieEchoChunk::kType) {
+ // Handled in chunk handler (due to RFC 4960, section 5.2.4).
+ return true;
+ }
+
+ if (packet.descriptors().size() == 1 &&
+ packet.descriptors()[0].type == ShutdownCompleteChunk::kType) {
+ // https://tools.ietf.org/html/rfc4960#section-8.5.1
+ // "The receiver of a SHUTDOWN COMPLETE shall accept the packet if the
+ // Verification Tag field of the packet matches its own tag and the T bit is
+ // not set OR if it is set to its peer's tag and the T bit is set in the
+ // Chunk Flags. Otherwise, the receiver MUST silently discard the packet
+ // and take no further action."
+ bool t_bit = (packet.descriptors()[0].flags & 0x01) != 0;
+ if (t_bit && tcb_ == nullptr) {
+ // Can't verify the tag - assume it's okey.
+ return true;
+ }
+ if ((!t_bit && header.verification_tag == my_verification_tag) ||
+ (t_bit && header.verification_tag == tcb_->peer_verification_tag())) {
+ return true;
+ }
+ callbacks_.OnError(ErrorKind::kParseFailed,
+ "SHUTDOWN_COMPLETE chunk verification tag was wrong");
+ return false;
+ }
+
+ // https://tools.ietf.org/html/rfc4960#section-8.5
+ // "When receiving an SCTP packet, the endpoint MUST ensure that the value
+ // in the Verification Tag field of the received SCTP packet matches its own
+ // tag. If the received Verification Tag value does not match the receiver's
+ // own tag value, the receiver shall silently discard the packet and shall not
+ // process it any further..."
+ if (header.verification_tag == my_verification_tag) {
+ return true;
+ }
+
+ callbacks_.OnError(
+ ErrorKind::kParseFailed,
+ rtc::StringFormat(
+ "Packet has invalid verification tag: %08x, expected %08x",
+ *header.verification_tag, *my_verification_tag));
+ return false;
+}
+
+void DcSctpSocket::HandleTimeout(TimeoutID timeout_id) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ timer_manager_.HandleTimeout(timeout_id);
+
+ if (tcb_ != nullptr && tcb_->HasTooManyTxErrors()) {
+ // Tearing down the TCB has to be done outside the handlers.
+ CloseConnectionBecauseOfTooManyTransmissionErrors();
+ }
+
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::ReceivePacket(rtc::ArrayView<const uint8_t> data) {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ ++metrics_.rx_packets_count;
+
+ if (packet_observer_ != nullptr) {
+ packet_observer_->OnReceivedPacket(callbacks_.TimeMillis(), data);
+ }
+
+ absl::optional<SctpPacket> packet =
+ SctpPacket::Parse(data, options_.disable_checksum_verification);
+ if (!packet.has_value()) {
+ // https://tools.ietf.org/html/rfc4960#section-6.8
+ // "The default procedure for handling invalid SCTP packets is to
+ // silently discard them."
+ callbacks_.OnError(ErrorKind::kParseFailed,
+ "Failed to parse received SCTP packet");
+ RTC_DCHECK(IsConsistent());
+ return;
+ }
+
+ if (RTC_DLOG_IS_ON) {
+ for (const auto& descriptor : packet->descriptors()) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Received "
+ << DebugConvertChunkToString(descriptor.data);
+ }
+ }
+
+ if (!ValidatePacket(*packet)) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Packet failed verification tag check - dropping";
+ RTC_DCHECK(IsConsistent());
+ return;
+ }
+
+ MaybeSendShutdownOnPacketReceived(*packet);
+
+ for (const auto& descriptor : packet->descriptors()) {
+ if (!Dispatch(packet->common_header(), descriptor)) {
+ break;
+ }
+ }
+
+ if (tcb_ != nullptr) {
+ tcb_->data_tracker().ObservePacketEnd();
+ tcb_->MaybeSendSack();
+ }
+
+ RTC_DCHECK(IsConsistent());
+}
+
+void DcSctpSocket::DebugPrintOutgoing(rtc::ArrayView<const uint8_t> payload) {
+ auto packet = SctpPacket::Parse(payload);
+ RTC_DCHECK(packet.has_value());
+
+ for (const auto& desc : packet->descriptors()) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Sent "
+ << DebugConvertChunkToString(desc.data);
+ }
+}
+
+bool DcSctpSocket::Dispatch(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ switch (descriptor.type) {
+ case DataChunk::kType:
+ HandleData(header, descriptor);
+ break;
+ case InitChunk::kType:
+ HandleInit(header, descriptor);
+ break;
+ case InitAckChunk::kType:
+ HandleInitAck(header, descriptor);
+ break;
+ case SackChunk::kType:
+ HandleSack(header, descriptor);
+ break;
+ case HeartbeatRequestChunk::kType:
+ HandleHeartbeatRequest(header, descriptor);
+ break;
+ case HeartbeatAckChunk::kType:
+ HandleHeartbeatAck(header, descriptor);
+ break;
+ case AbortChunk::kType:
+ HandleAbort(header, descriptor);
+ break;
+ case ErrorChunk::kType:
+ HandleError(header, descriptor);
+ break;
+ case CookieEchoChunk::kType:
+ HandleCookieEcho(header, descriptor);
+ break;
+ case CookieAckChunk::kType:
+ HandleCookieAck(header, descriptor);
+ break;
+ case ShutdownChunk::kType:
+ HandleShutdown(header, descriptor);
+ break;
+ case ShutdownAckChunk::kType:
+ HandleShutdownAck(header, descriptor);
+ break;
+ case ShutdownCompleteChunk::kType:
+ HandleShutdownComplete(header, descriptor);
+ break;
+ case ReConfigChunk::kType:
+ HandleReconfig(header, descriptor);
+ break;
+ case ForwardTsnChunk::kType:
+ HandleForwardTsn(header, descriptor);
+ break;
+ case IDataChunk::kType:
+ HandleIData(header, descriptor);
+ break;
+ case IForwardTsnChunk::kType:
+ HandleIForwardTsn(header, descriptor);
+ break;
+ default:
+ return HandleUnrecognizedChunk(descriptor);
+ }
+ return true;
+}
+
+bool DcSctpSocket::HandleUnrecognizedChunk(
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ bool report_as_error = (descriptor.type & 0x40) != 0;
+ bool continue_processing = (descriptor.type & 0x80) != 0;
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Received unknown chunk: "
+ << static_cast<int>(descriptor.type);
+ if (report_as_error) {
+ rtc::StringBuilder sb;
+ sb << "Received unknown chunk of type: "
+ << static_cast<int>(descriptor.type) << " with report-error bit set";
+ callbacks_.OnError(ErrorKind::kParseFailed, sb.str());
+ RTC_DLOG(LS_VERBOSE)
+ << log_prefix()
+ << "Unknown chunk, with type indicating it should be reported.";
+
+ // https://tools.ietf.org/html/rfc4960#section-3.2
+ // "... report in an ERROR chunk using the 'Unrecognized Chunk Type'
+ // cause."
+ if (tcb_ != nullptr) {
+ // Need TCB - this chunk must be sent with a correct verification tag.
+ packet_sender_.Send(tcb_->PacketBuilder().Add(
+ ErrorChunk(Parameters::Builder()
+ .Add(UnrecognizedChunkTypeCause(std::vector<uint8_t>(
+ descriptor.data.begin(), descriptor.data.end())))
+ .Build())));
+ }
+ }
+ if (!continue_processing) {
+ // https://tools.ietf.org/html/rfc4960#section-3.2
+ // "Stop processing this SCTP packet and discard it, do not process any
+ // further chunks within it."
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Unknown chunk, with type indicating not to "
+ "process any further chunks";
+ }
+
+ return continue_processing;
+}
+
+absl::optional<DurationMs> DcSctpSocket::OnInitTimerExpiry() {
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Timer " << t1_init_->name()
+ << " has expired: " << t1_init_->expiration_count()
+ << "/" << t1_init_->options().max_restarts.value_or(-1);
+ RTC_DCHECK(state_ == State::kCookieWait);
+
+ if (t1_init_->is_running()) {
+ SendInit();
+ } else {
+ InternalClose(ErrorKind::kTooManyRetries, "No INIT_ACK received");
+ }
+ RTC_DCHECK(IsConsistent());
+ return absl::nullopt;
+}
+
+absl::optional<DurationMs> DcSctpSocket::OnCookieTimerExpiry() {
+ // https://tools.ietf.org/html/rfc4960#section-4
+ // "If the T1-cookie timer expires, the endpoint MUST retransmit COOKIE
+ // ECHO and restart the T1-cookie timer without changing state. This MUST
+ // be repeated up to 'Max.Init.Retransmits' times. After that, the endpoint
+ // MUST abort the initialization process and report the error to the SCTP
+ // user."
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Timer " << t1_cookie_->name()
+ << " has expired: " << t1_cookie_->expiration_count()
+ << "/"
+ << t1_cookie_->options().max_restarts.value_or(-1);
+
+ RTC_DCHECK(state_ == State::kCookieEchoed);
+
+ if (t1_cookie_->is_running()) {
+ tcb_->SendBufferedPackets(callbacks_.TimeMillis());
+ } else {
+ InternalClose(ErrorKind::kTooManyRetries, "No COOKIE_ACK received");
+ }
+
+ RTC_DCHECK(IsConsistent());
+ return absl::nullopt;
+}
+
+absl::optional<DurationMs> DcSctpSocket::OnShutdownTimerExpiry() {
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Timer " << t2_shutdown_->name()
+ << " has expired: " << t2_shutdown_->expiration_count()
+ << "/"
+ << t2_shutdown_->options().max_restarts.value_or(-1);
+
+ if (!t2_shutdown_->is_running()) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "An endpoint should limit the number of retransmissions of the SHUTDOWN
+ // chunk to the protocol parameter 'Association.Max.Retrans'. If this
+ // threshold is exceeded, the endpoint should destroy the TCB..."
+
+ packet_sender_.Send(tcb_->PacketBuilder().Add(
+ AbortChunk(true, Parameters::Builder()
+ .Add(UserInitiatedAbortCause(
+ "Too many retransmissions of SHUTDOWN"))
+ .Build())));
+
+ InternalClose(ErrorKind::kTooManyRetries, "No SHUTDOWN_ACK received");
+ RTC_DCHECK(IsConsistent());
+ return absl::nullopt;
+ }
+
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "If the timer expires, the endpoint must resend the SHUTDOWN with the
+ // updated last sequential TSN received from its peer."
+ SendShutdown();
+ RTC_DCHECK(IsConsistent());
+ return tcb_->current_rto();
+}
+
+void DcSctpSocket::OnSentPacket(rtc::ArrayView<const uint8_t> packet,
+ SendPacketStatus status) {
+ // The packet observer is invoked even if the packet was failed to be sent, to
+ // indicate an attempt was made.
+ if (packet_observer_ != nullptr) {
+ packet_observer_->OnSentPacket(callbacks_.TimeMillis(), packet);
+ }
+
+ if (status == SendPacketStatus::kSuccess) {
+ if (RTC_DLOG_IS_ON) {
+ DebugPrintOutgoing(packet);
+ }
+
+ // The heartbeat interval timer is restarted for every sent packet, to
+ // fire when the outgoing channel is inactive.
+ if (tcb_ != nullptr) {
+ tcb_->heartbeat_handler().RestartTimer();
+ }
+
+ ++metrics_.tx_packets_count;
+ }
+}
+
+bool DcSctpSocket::ValidateHasTCB() {
+ if (tcb_ != nullptr) {
+ return true;
+ }
+
+ callbacks_.OnError(
+ ErrorKind::kNotConnected,
+ "Received unexpected commands on socket that is not connected");
+ return false;
+}
+
+void DcSctpSocket::ReportFailedToParseChunk(int chunk_type) {
+ rtc::StringBuilder sb;
+ sb << "Failed to parse chunk of type: " << chunk_type;
+ callbacks_.OnError(ErrorKind::kParseFailed, sb.str());
+}
+
+void DcSctpSocket::HandleData(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<DataChunk> chunk = DataChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ HandleDataCommon(*chunk);
+ }
+}
+
+void DcSctpSocket::HandleIData(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<IDataChunk> chunk = IDataChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ HandleDataCommon(*chunk);
+ }
+}
+
+void DcSctpSocket::HandleDataCommon(AnyDataChunk& chunk) {
+ TSN tsn = chunk.tsn();
+ AnyDataChunk::ImmediateAckFlag immediate_ack = chunk.options().immediate_ack;
+ Data data = std::move(chunk).extract();
+
+ if (data.payload.empty()) {
+ // Empty DATA chunks are illegal.
+ packet_sender_.Send(tcb_->PacketBuilder().Add(
+ ErrorChunk(Parameters::Builder().Add(NoUserDataCause(tsn)).Build())));
+ callbacks_.OnError(ErrorKind::kProtocolViolation,
+ "Received DATA chunk with no user data");
+ return;
+ }
+
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Handle DATA, queue_size="
+ << tcb_->reassembly_queue().queued_bytes()
+ << ", water_mark="
+ << tcb_->reassembly_queue().watermark_bytes()
+ << ", full=" << tcb_->reassembly_queue().is_full()
+ << ", above="
+ << tcb_->reassembly_queue().is_above_watermark();
+
+ if (tcb_->reassembly_queue().is_full()) {
+ // If the reassembly queue is full, there is nothing that can be done. The
+ // specification only allows dropping gap-ack-blocks, and that's not
+ // likely to help as the socket has been trying to fill gaps since the
+ // watermark was reached.
+ packet_sender_.Send(tcb_->PacketBuilder().Add(AbortChunk(
+ true, Parameters::Builder().Add(OutOfResourceErrorCause()).Build())));
+ InternalClose(ErrorKind::kResourceExhaustion,
+ "Reassembly Queue is exhausted");
+ return;
+ }
+
+ if (tcb_->reassembly_queue().is_above_watermark()) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Is above high watermark";
+ // If the reassembly queue is above its high watermark, only accept data
+ // chunks that increase its cumulative ack tsn in an attempt to fill gaps
+ // to deliver messages.
+ if (!tcb_->data_tracker().will_increase_cum_ack_tsn(tsn)) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Rejected data because of exceeding watermark";
+ tcb_->data_tracker().ForceImmediateSack();
+ return;
+ }
+ }
+
+ if (!tcb_->data_tracker().IsTSNValid(tsn)) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Rejected data because of failing TSN validity";
+ return;
+ }
+
+ if (tcb_->data_tracker().Observe(tsn, immediate_ack)) {
+ tcb_->reassembly_queue().Add(tsn, std::move(data));
+ tcb_->reassembly_queue().MaybeResetStreamsDeferred(
+ tcb_->data_tracker().last_cumulative_acked_tsn());
+ DeliverReassembledMessages();
+ }
+}
+
+void DcSctpSocket::HandleInit(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<InitChunk> chunk = InitChunk::Parse(descriptor.data);
+ if (!ValidateParseSuccess(chunk)) {
+ return;
+ }
+
+ if (chunk->initiate_tag() == VerificationTag(0) ||
+ chunk->nbr_outbound_streams() == 0 || chunk->nbr_inbound_streams() == 0) {
+ // https://tools.ietf.org/html/rfc4960#section-3.3.2
+ // "If the value of the Initiate Tag in a received INIT chunk is found
+ // to be 0, the receiver MUST treat it as an error and close the
+ // association by transmitting an ABORT."
+
+ // "A receiver of an INIT with the OS value set to 0 SHOULD abort the
+ // association."
+
+ // "A receiver of an INIT with the MIS value of 0 SHOULD abort the
+ // association."
+
+ packet_sender_.Send(
+ SctpPacket::Builder(VerificationTag(0), options_)
+ .Add(AbortChunk(
+ /*filled_in_verification_tag=*/false,
+ Parameters::Builder()
+ .Add(ProtocolViolationCause("INIT malformed"))
+ .Build())));
+ InternalClose(ErrorKind::kProtocolViolation, "Received invalid INIT");
+ return;
+ }
+
+ if (state_ == State::kShutdownAckSent) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "If an endpoint is in the SHUTDOWN-ACK-SENT state and receives an
+ // INIT chunk (e.g., if the SHUTDOWN COMPLETE was lost) with source and
+ // destination transport addresses (either in the IP addresses or in the
+ // INIT chunk) that belong to this association, it should discard the INIT
+ // chunk and retransmit the SHUTDOWN ACK chunk."
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received Init indicating lost ShutdownComplete";
+ SendShutdownAck();
+ return;
+ }
+
+ TieTag tie_tag(0);
+ if (state_ == State::kClosed) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received Init in closed state (normal)";
+
+ MakeConnectionParameters();
+ } else if (state_ == State::kCookieWait || state_ == State::kCookieEchoed) {
+ // https://tools.ietf.org/html/rfc4960#section-5.2.1
+ // "This usually indicates an initialization collision, i.e., each
+ // endpoint is attempting, at about the same time, to establish an
+ // association with the other endpoint. Upon receipt of an INIT in the
+ // COOKIE-WAIT state, an endpoint MUST respond with an INIT ACK using the
+ // same parameters it sent in its original INIT chunk (including its
+ // Initiate Tag, unchanged). When responding, the endpoint MUST send the
+ // INIT ACK back to the same address that the original INIT (sent by this
+ // endpoint) was sent."
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received Init indicating simultaneous connections";
+ } else {
+ RTC_DCHECK(tcb_ != nullptr);
+ // https://tools.ietf.org/html/rfc4960#section-5.2.2
+ // "The outbound SCTP packet containing this INIT ACK MUST carry a
+ // Verification Tag value equal to the Initiate Tag found in the
+ // unexpected INIT. And the INIT ACK MUST contain a new Initiate Tag
+ // (randomly generated; see Section 5.3.1). Other parameters for the
+ // endpoint SHOULD be copied from the existing parameters of the
+ // association (e.g., number of outbound streams) into the INIT ACK and
+ // cookie."
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received Init indicating restarted connection";
+ // Create a new verification tag - different from the previous one.
+ for (int tries = 0; tries < 10; ++tries) {
+ connect_params_.verification_tag = VerificationTag(
+ callbacks_.GetRandomInt(kMinVerificationTag, kMaxVerificationTag));
+ if (connect_params_.verification_tag != tcb_->my_verification_tag()) {
+ break;
+ }
+ }
+
+ // Make the initial TSN make a large jump, so that there is no overlap
+ // with the old and new association.
+ connect_params_.initial_tsn =
+ TSN(*tcb_->retransmission_queue().next_tsn() + 1000000);
+ tie_tag = tcb_->tie_tag();
+ }
+
+ RTC_DLOG(LS_VERBOSE)
+ << log_prefix()
+ << rtc::StringFormat(
+ "Proceeding with connection. my_verification_tag=%08x, "
+ "my_initial_tsn=%u, peer_verification_tag=%08x, "
+ "peer_initial_tsn=%u",
+ *connect_params_.verification_tag, *connect_params_.initial_tsn,
+ *chunk->initiate_tag(), *chunk->initial_tsn());
+
+ Capabilities capabilities =
+ ComputeCapabilities(options_, chunk->nbr_outbound_streams(),
+ chunk->nbr_inbound_streams(), chunk->parameters());
+
+ SctpPacket::Builder b(chunk->initiate_tag(), options_);
+ Parameters::Builder params_builder =
+ Parameters::Builder().Add(StateCookieParameter(
+ StateCookie(chunk->initiate_tag(), chunk->initial_tsn(),
+ chunk->a_rwnd(), tie_tag, capabilities)
+ .Serialize()));
+ AddCapabilityParameters(options_, params_builder);
+
+ InitAckChunk init_ack(/*initiate_tag=*/connect_params_.verification_tag,
+ options_.max_receiver_window_buffer_size,
+ options_.announced_maximum_outgoing_streams,
+ options_.announced_maximum_incoming_streams,
+ connect_params_.initial_tsn, params_builder.Build());
+ b.Add(init_ack);
+ packet_sender_.Send(b);
+}
+
+void DcSctpSocket::HandleInitAck(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<InitAckChunk> chunk = InitAckChunk::Parse(descriptor.data);
+ if (!ValidateParseSuccess(chunk)) {
+ return;
+ }
+
+ if (state_ != State::kCookieWait) {
+ // https://tools.ietf.org/html/rfc4960#section-5.2.3
+ // "If an INIT ACK is received by an endpoint in any state other than
+ // the COOKIE-WAIT state, the endpoint should discard the INIT ACK chunk."
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received INIT_ACK in unexpected state";
+ return;
+ }
+
+ auto cookie = chunk->parameters().get<StateCookieParameter>();
+ if (!cookie.has_value()) {
+ packet_sender_.Send(
+ SctpPacket::Builder(connect_params_.verification_tag, options_)
+ .Add(AbortChunk(
+ /*filled_in_verification_tag=*/false,
+ Parameters::Builder()
+ .Add(ProtocolViolationCause("INIT-ACK malformed"))
+ .Build())));
+ InternalClose(ErrorKind::kProtocolViolation,
+ "InitAck chunk doesn't contain a cookie");
+ return;
+ }
+ Capabilities capabilities =
+ ComputeCapabilities(options_, chunk->nbr_outbound_streams(),
+ chunk->nbr_inbound_streams(), chunk->parameters());
+ t1_init_->Stop();
+
+ metrics_.peer_implementation = DeterminePeerImplementation(cookie->data());
+
+ // If the connection is re-established (peer restarted, but re-used old
+ // connection), make sure that all message identifiers are reset and any
+ // partly sent message is re-sent in full. The same is true when the socket
+ // is closed and later re-opened, which never happens in WebRTC, but is a
+ // valid operation on the SCTP level. Note that in case of handover, the
+ // send queue is already re-configured, and shouldn't be reset.
+ send_queue_.Reset();
+
+ CreateTransmissionControlBlock(capabilities, connect_params_.verification_tag,
+ connect_params_.initial_tsn,
+ chunk->initiate_tag(), chunk->initial_tsn(),
+ chunk->a_rwnd(), MakeTieTag(callbacks_));
+
+ SetState(State::kCookieEchoed, "INIT_ACK received");
+
+ // The connection isn't fully established just yet.
+ tcb_->SetCookieEchoChunk(CookieEchoChunk(cookie->data()));
+ tcb_->SendBufferedPackets(callbacks_.TimeMillis());
+ t1_cookie_->Start();
+}
+
+void DcSctpSocket::HandleCookieEcho(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<CookieEchoChunk> chunk =
+ CookieEchoChunk::Parse(descriptor.data);
+ if (!ValidateParseSuccess(chunk)) {
+ return;
+ }
+
+ absl::optional<StateCookie> cookie =
+ StateCookie::Deserialize(chunk->cookie());
+ if (!cookie.has_value()) {
+ callbacks_.OnError(ErrorKind::kParseFailed, "Failed to parse state cookie");
+ return;
+ }
+
+ if (tcb_ != nullptr) {
+ if (!HandleCookieEchoWithTCB(header, *cookie)) {
+ return;
+ }
+ } else {
+ if (header.verification_tag != connect_params_.verification_tag) {
+ callbacks_.OnError(
+ ErrorKind::kParseFailed,
+ rtc::StringFormat(
+ "Received CookieEcho with invalid verification tag: %08x, "
+ "expected %08x",
+ *header.verification_tag, *connect_params_.verification_tag));
+ return;
+ }
+ }
+
+ // The init timer can be running on simultaneous connections.
+ t1_init_->Stop();
+ t1_cookie_->Stop();
+ if (state_ != State::kEstablished) {
+ if (tcb_ != nullptr) {
+ tcb_->ClearCookieEchoChunk();
+ }
+ SetState(State::kEstablished, "COOKIE_ECHO received");
+ callbacks_.OnConnected();
+ }
+
+ if (tcb_ == nullptr) {
+ // If the connection is re-established (peer restarted, but re-used old
+ // connection), make sure that all message identifiers are reset and any
+ // partly sent message is re-sent in full. The same is true when the socket
+ // is closed and later re-opened, which never happens in WebRTC, but is a
+ // valid operation on the SCTP level. Note that in case of handover, the
+ // send queue is already re-configured, and shouldn't be reset.
+ send_queue_.Reset();
+
+ CreateTransmissionControlBlock(
+ cookie->capabilities(), connect_params_.verification_tag,
+ connect_params_.initial_tsn, cookie->initiate_tag(),
+ cookie->initial_tsn(), cookie->a_rwnd(), MakeTieTag(callbacks_));
+ }
+
+ SctpPacket::Builder b = tcb_->PacketBuilder();
+ b.Add(CookieAckChunk());
+
+ // https://tools.ietf.org/html/rfc4960#section-5.1
+ // "A COOKIE ACK chunk may be bundled with any pending DATA chunks (and/or
+ // SACK chunks), but the COOKIE ACK chunk MUST be the first chunk in the
+ // packet."
+ tcb_->SendBufferedPackets(b, callbacks_.TimeMillis());
+}
+
+bool DcSctpSocket::HandleCookieEchoWithTCB(const CommonHeader& header,
+ const StateCookie& cookie) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Handling CookieEchoChunk with TCB. local_tag="
+ << *tcb_->my_verification_tag()
+ << ", peer_tag=" << *header.verification_tag
+ << ", tcb_tag=" << *tcb_->peer_verification_tag()
+ << ", cookie_tag=" << *cookie.initiate_tag()
+ << ", local_tie_tag=" << *tcb_->tie_tag()
+ << ", peer_tie_tag=" << *cookie.tie_tag();
+ // https://tools.ietf.org/html/rfc4960#section-5.2.4
+ // "Handle a COOKIE ECHO when a TCB Exists"
+ if (header.verification_tag != tcb_->my_verification_tag() &&
+ tcb_->peer_verification_tag() != cookie.initiate_tag() &&
+ cookie.tie_tag() == tcb_->tie_tag()) {
+ // "A) In this case, the peer may have restarted."
+ if (state_ == State::kShutdownAckSent) {
+ // "If the endpoint is in the SHUTDOWN-ACK-SENT state and recognizes
+ // that the peer has restarted ... it MUST NOT set up a new association
+ // but instead resend the SHUTDOWN ACK and send an ERROR chunk with a
+ // "Cookie Received While Shutting Down" error cause to its peer."
+ SctpPacket::Builder b(cookie.initiate_tag(), options_);
+ b.Add(ShutdownAckChunk());
+ b.Add(ErrorChunk(Parameters::Builder()
+ .Add(CookieReceivedWhileShuttingDownCause())
+ .Build()));
+ packet_sender_.Send(b);
+ callbacks_.OnError(ErrorKind::kWrongSequence,
+ "Received COOKIE-ECHO while shutting down");
+ return false;
+ }
+
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received COOKIE-ECHO indicating a restarted peer";
+
+ tcb_ = nullptr;
+ callbacks_.OnConnectionRestarted();
+ } else if (header.verification_tag == tcb_->my_verification_tag() &&
+ tcb_->peer_verification_tag() != cookie.initiate_tag()) {
+ // TODO(boivie): Handle the peer_tag == 0?
+ // "B) In this case, both sides may be attempting to start an
+ // association at about the same time, but the peer endpoint started its
+ // INIT after responding to the local endpoint's INIT."
+ RTC_DLOG(LS_VERBOSE)
+ << log_prefix()
+ << "Received COOKIE-ECHO indicating simultaneous connections";
+ tcb_ = nullptr;
+ } else if (header.verification_tag != tcb_->my_verification_tag() &&
+ tcb_->peer_verification_tag() == cookie.initiate_tag() &&
+ cookie.tie_tag() == TieTag(0)) {
+ // "C) In this case, the local endpoint's cookie has arrived late.
+ // Before it arrived, the local endpoint sent an INIT and received an
+ // INIT ACK and finally sent a COOKIE ECHO with the peer's same tag but
+ // a new tag of its own. The cookie should be silently discarded. The
+ // endpoint SHOULD NOT change states and should leave any timers
+ // running."
+ RTC_DLOG(LS_VERBOSE)
+ << log_prefix()
+ << "Received COOKIE-ECHO indicating a late COOKIE-ECHO. Discarding";
+ return false;
+ } else if (header.verification_tag == tcb_->my_verification_tag() &&
+ tcb_->peer_verification_tag() == cookie.initiate_tag()) {
+ // "D) When both local and remote tags match, the endpoint should enter
+ // the ESTABLISHED state, if it is in the COOKIE-ECHOED state. It
+ // should stop any cookie timer that may be running and send a COOKIE
+ // ACK."
+ RTC_DLOG(LS_VERBOSE)
+ << log_prefix()
+ << "Received duplicate COOKIE-ECHO, probably because of peer not "
+ "receiving COOKIE-ACK and retransmitting COOKIE-ECHO. Continuing.";
+ }
+ return true;
+}
+
+void DcSctpSocket::HandleCookieAck(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<CookieAckChunk> chunk = CookieAckChunk::Parse(descriptor.data);
+ if (!ValidateParseSuccess(chunk)) {
+ return;
+ }
+
+ if (state_ != State::kCookieEchoed) {
+ // https://tools.ietf.org/html/rfc4960#section-5.2.5
+ // "At any state other than COOKIE-ECHOED, an endpoint should silently
+ // discard a received COOKIE ACK chunk."
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received COOKIE_ACK not in COOKIE_ECHOED state";
+ return;
+ }
+
+ // RFC 4960, Errata ID: 4400
+ t1_cookie_->Stop();
+ tcb_->ClearCookieEchoChunk();
+ SetState(State::kEstablished, "COOKIE_ACK received");
+ tcb_->SendBufferedPackets(callbacks_.TimeMillis());
+ callbacks_.OnConnected();
+}
+
+void DcSctpSocket::DeliverReassembledMessages() {
+ if (tcb_->reassembly_queue().HasMessages()) {
+ for (auto& message : tcb_->reassembly_queue().FlushMessages()) {
+ ++metrics_.rx_messages_count;
+ callbacks_.OnMessageReceived(std::move(message));
+ }
+ }
+}
+
+void DcSctpSocket::HandleSack(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<SackChunk> chunk = SackChunk::Parse(descriptor.data);
+
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ TimeMs now = callbacks_.TimeMillis();
+ SackChunk sack = ChunkValidators::Clean(*std::move(chunk));
+
+ if (tcb_->retransmission_queue().HandleSack(now, sack)) {
+ MaybeSendShutdownOrAck();
+ // Receiving an ACK may make the socket go into fast recovery mode.
+ // https://datatracker.ietf.org/doc/html/rfc4960#section-7.2.4
+ // "Determine how many of the earliest (i.e., lowest TSN) DATA chunks
+ // marked for retransmission will fit into a single packet, subject to
+ // constraint of the path MTU of the destination transport address to
+ // which the packet is being sent. Call this value K. Retransmit those K
+ // DATA chunks in a single packet. When a Fast Retransmit is being
+ // performed, the sender SHOULD ignore the value of cwnd and SHOULD NOT
+ // delay retransmission for this single packet."
+ tcb_->MaybeSendFastRetransmit();
+
+ // Receiving an ACK will decrease outstanding bytes (maybe now below
+ // cwnd?) or indicate packet loss that may result in sending FORWARD-TSN.
+ tcb_->SendBufferedPackets(now);
+ } else {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Dropping out-of-order SACK with TSN "
+ << *sack.cumulative_tsn_ack();
+ }
+ }
+}
+
+void DcSctpSocket::HandleHeartbeatRequest(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<HeartbeatRequestChunk> chunk =
+ HeartbeatRequestChunk::Parse(descriptor.data);
+
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ tcb_->heartbeat_handler().HandleHeartbeatRequest(*std::move(chunk));
+ }
+}
+
+void DcSctpSocket::HandleHeartbeatAck(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<HeartbeatAckChunk> chunk =
+ HeartbeatAckChunk::Parse(descriptor.data);
+
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ tcb_->heartbeat_handler().HandleHeartbeatAck(*std::move(chunk));
+ }
+}
+
+void DcSctpSocket::HandleAbort(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<AbortChunk> chunk = AbortChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk)) {
+ std::string error_string = ErrorCausesToString(chunk->error_causes());
+ if (tcb_ == nullptr) {
+ // https://tools.ietf.org/html/rfc4960#section-3.3.7
+ // "If an endpoint receives an ABORT with a format error or no TCB is
+ // found, it MUST silently discard it."
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Received ABORT (" << error_string
+ << ") on a connection with no TCB. Ignoring";
+ return;
+ }
+
+ RTC_DLOG(LS_WARNING) << log_prefix() << "Received ABORT (" << error_string
+ << ") - closing connection.";
+ InternalClose(ErrorKind::kPeerReported, error_string);
+ }
+}
+
+void DcSctpSocket::HandleError(const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<ErrorChunk> chunk = ErrorChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk)) {
+ std::string error_string = ErrorCausesToString(chunk->error_causes());
+ if (tcb_ == nullptr) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix() << "Received ERROR (" << error_string
+ << ") on a connection with no TCB. Ignoring";
+ return;
+ }
+
+ RTC_DLOG(LS_WARNING) << log_prefix() << "Received ERROR: " << error_string;
+ callbacks_.OnError(ErrorKind::kPeerReported,
+ "Peer reported error: " + error_string);
+ }
+}
+
+void DcSctpSocket::HandleReconfig(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ TimeMs now = callbacks_.TimeMillis();
+ absl::optional<ReConfigChunk> chunk = ReConfigChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ tcb_->stream_reset_handler().HandleReConfig(*std::move(chunk));
+ // Handling this response may result in outgoing stream resets finishing
+ // (either successfully or with failure). If there still are pending streams
+ // that were waiting for this request to finish, continue resetting them.
+ MaybeSendResetStreamsRequest();
+
+ // If a response was processed, pending to-be-reset streams may now have
+ // become unpaused. Try to send more DATA chunks.
+ tcb_->SendBufferedPackets(now);
+ }
+}
+
+void DcSctpSocket::HandleShutdown(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ if (!ValidateParseSuccess(ShutdownChunk::Parse(descriptor.data))) {
+ return;
+ }
+
+ if (state_ == State::kClosed) {
+ return;
+ } else if (state_ == State::kCookieWait || state_ == State::kCookieEchoed) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "If a SHUTDOWN is received in the COOKIE-WAIT or COOKIE ECHOED state,
+ // the SHUTDOWN chunk SHOULD be silently discarded."
+ } else if (state_ == State::kShutdownSent) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "If an endpoint is in the SHUTDOWN-SENT state and receives a
+ // SHUTDOWN chunk from its peer, the endpoint shall respond immediately
+ // with a SHUTDOWN ACK to its peer, and move into the SHUTDOWN-ACK-SENT
+ // state restarting its T2-shutdown timer."
+ SendShutdownAck();
+ SetState(State::kShutdownAckSent, "SHUTDOWN received");
+ } else if (state_ == State::kShutdownAckSent) {
+ // TODO(webrtc:12739): This condition should be removed and handled by the
+ // next (state_ != State::kShutdownReceived).
+ return;
+ } else if (state_ != State::kShutdownReceived) {
+ RTC_DLOG(LS_VERBOSE) << log_prefix()
+ << "Received SHUTDOWN - shutting down the socket";
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "Upon reception of the SHUTDOWN, the peer endpoint shall enter the
+ // SHUTDOWN-RECEIVED state, stop accepting new data from its SCTP user,
+ // and verify, by checking the Cumulative TSN Ack field of the chunk, that
+ // all its outstanding DATA chunks have been received by the SHUTDOWN
+ // sender."
+ SetState(State::kShutdownReceived, "SHUTDOWN received");
+ MaybeSendShutdownOrAck();
+ }
+}
+
+void DcSctpSocket::HandleShutdownAck(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ if (!ValidateParseSuccess(ShutdownAckChunk::Parse(descriptor.data))) {
+ return;
+ }
+
+ if (state_ == State::kShutdownSent || state_ == State::kShutdownAckSent) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall stop
+ // the T2-shutdown timer, send a SHUTDOWN COMPLETE chunk to its peer, and
+ // remove all record of the association."
+
+ // "If an endpoint is in the SHUTDOWN-ACK-SENT state and receives a
+ // SHUTDOWN ACK, it shall stop the T2-shutdown timer, send a SHUTDOWN
+ // COMPLETE chunk to its peer, and remove all record of the association."
+
+ SctpPacket::Builder b = tcb_->PacketBuilder();
+ b.Add(ShutdownCompleteChunk(/*tag_reflected=*/false));
+ packet_sender_.Send(b);
+ InternalClose(ErrorKind::kNoError, "");
+ } else {
+ // https://tools.ietf.org/html/rfc4960#section-8.5.1
+ // "If the receiver is in COOKIE-ECHOED or COOKIE-WAIT state
+ // the procedures in Section 8.4 SHOULD be followed; in other words, it
+ // should be treated as an Out Of The Blue packet."
+
+ // https://tools.ietf.org/html/rfc4960#section-8.4
+ // "If the packet contains a SHUTDOWN ACK chunk, the receiver
+ // should respond to the sender of the OOTB packet with a SHUTDOWN
+ // COMPLETE. When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
+ // packet must fill in the Verification Tag field of the outbound packet
+ // with the Verification Tag received in the SHUTDOWN ACK and set the T
+ // bit in the Chunk Flags to indicate that the Verification Tag is
+ // reflected."
+
+ SctpPacket::Builder b(header.verification_tag, options_);
+ b.Add(ShutdownCompleteChunk(/*tag_reflected=*/true));
+ packet_sender_.Send(b);
+ }
+}
+
+void DcSctpSocket::HandleShutdownComplete(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ if (!ValidateParseSuccess(ShutdownCompleteChunk::Parse(descriptor.data))) {
+ return;
+ }
+
+ if (state_ == State::kShutdownAckSent) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "Upon reception of the SHUTDOWN COMPLETE chunk, the endpoint will
+ // verify that it is in the SHUTDOWN-ACK-SENT state; if it is not, the
+ // chunk should be discarded. If the endpoint is in the SHUTDOWN-ACK-SENT
+ // state, the endpoint should stop the T2-shutdown timer and remove all
+ // knowledge of the association (and thus the association enters the
+ // CLOSED state)."
+ InternalClose(ErrorKind::kNoError, "");
+ }
+}
+
+void DcSctpSocket::HandleForwardTsn(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<ForwardTsnChunk> chunk =
+ ForwardTsnChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ HandleForwardTsnCommon(*chunk);
+ }
+}
+
+void DcSctpSocket::HandleIForwardTsn(
+ const CommonHeader& header,
+ const SctpPacket::ChunkDescriptor& descriptor) {
+ absl::optional<IForwardTsnChunk> chunk =
+ IForwardTsnChunk::Parse(descriptor.data);
+ if (ValidateParseSuccess(chunk) && ValidateHasTCB()) {
+ HandleForwardTsnCommon(*chunk);
+ }
+}
+
+void DcSctpSocket::HandleForwardTsnCommon(const AnyForwardTsnChunk& chunk) {
+ if (!tcb_->capabilities().partial_reliability) {
+ SctpPacket::Builder b = tcb_->PacketBuilder();
+ b.Add(AbortChunk(/*filled_in_verification_tag=*/true,
+ Parameters::Builder()
+ .Add(ProtocolViolationCause(
+ "I-FORWARD-TSN received, but not indicated "
+ "during connection establishment"))
+ .Build()));
+ packet_sender_.Send(b);
+
+ callbacks_.OnError(ErrorKind::kProtocolViolation,
+ "Received a FORWARD_TSN without announced peer support");
+ return;
+ }
+ tcb_->data_tracker().HandleForwardTsn(chunk.new_cumulative_tsn());
+ tcb_->reassembly_queue().Handle(chunk);
+ // A forward TSN - for ordered streams - may allow messages to be
+ // delivered.
+ DeliverReassembledMessages();
+
+ // Processing a FORWARD_TSN might result in sending a SACK.
+ tcb_->MaybeSendSack();
+}
+
+void DcSctpSocket::MaybeSendShutdownOrAck() {
+ if (tcb_->retransmission_queue().outstanding_bytes() != 0) {
+ return;
+ }
+
+ if (state_ == State::kShutdownPending) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "Once all its outstanding data has been acknowledged, the endpoint
+ // shall send a SHUTDOWN chunk to its peer including in the Cumulative TSN
+ // Ack field the last sequential TSN it has received from the peer. It
+ // shall then start the T2-shutdown timer and enter the SHUTDOWN-SENT
+ // state.""
+
+ SendShutdown();
+ t2_shutdown_->set_duration(tcb_->current_rto());
+ t2_shutdown_->Start();
+ SetState(State::kShutdownSent, "No more outstanding data");
+ } else if (state_ == State::kShutdownReceived) {
+ // https://tools.ietf.org/html/rfc4960#section-9.2
+ // "If the receiver of the SHUTDOWN has no more outstanding DATA
+ // chunks, the SHUTDOWN receiver MUST send a SHUTDOWN ACK and start a
+ // T2-shutdown timer of its own, entering the SHUTDOWN-ACK-SENT state. If
+ // the timer expires, the endpoint must resend the SHUTDOWN ACK."
+
+ SendShutdownAck();
+ SetState(State::kShutdownAckSent, "No more outstanding data");
+ }
+}
+
+void DcSctpSocket::SendShutdown() {
+ SctpPacket::Builder b = tcb_->PacketBuilder();
+ b.Add(ShutdownChunk(tcb_->data_tracker().last_cumulative_acked_tsn()));
+ packet_sender_.Send(b);
+}
+
+void DcSctpSocket::SendShutdownAck() {
+ packet_sender_.Send(tcb_->PacketBuilder().Add(ShutdownAckChunk()));
+ t2_shutdown_->set_duration(tcb_->current_rto());
+ t2_shutdown_->Start();
+}
+
+HandoverReadinessStatus DcSctpSocket::GetHandoverReadiness() const {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ HandoverReadinessStatus status;
+ if (state_ != State::kClosed && state_ != State::kEstablished) {
+ status.Add(HandoverUnreadinessReason::kWrongConnectionState);
+ }
+ status.Add(send_queue_.GetHandoverReadiness());
+ if (tcb_) {
+ status.Add(tcb_->GetHandoverReadiness());
+ }
+ return status;
+}
+
+absl::optional<DcSctpSocketHandoverState>
+DcSctpSocket::GetHandoverStateAndClose() {
+ RTC_DCHECK_RUN_ON(&thread_checker_);
+ CallbackDeferrer::ScopedDeferrer deferrer(callbacks_);
+
+ if (!GetHandoverReadiness().IsReady()) {
+ return absl::nullopt;
+ }
+
+ DcSctpSocketHandoverState state;
+
+ if (state_ == State::kClosed) {
+ state.socket_state = DcSctpSocketHandoverState::SocketState::kClosed;
+ } else if (state_ == State::kEstablished) {
+ state.socket_state = DcSctpSocketHandoverState::SocketState::kConnected;
+ tcb_->AddHandoverState(state);
+ send_queue_.AddHandoverState(state);
+ InternalClose(ErrorKind::kNoError, "handover");
+ }
+
+ return std::move(state);
+}
+
+} // namespace dcsctp