| /* |
| * 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/memory/memory.h" |
| #include "absl/strings/string_view.h" |
| #include "absl/types/optional.h" |
| #include "api/array_view.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/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 GetCapabilities(const DcSctpOptions& options, |
| 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; |
| } |
| 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)); |
| } |
| |
| } // 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]() { return callbacks_.CreateTimeout(); }), |
| t1_init_(timer_manager_.CreateTimer( |
| "t1-init", |
| [this]() { return OnInitTimerExpiry(); }, |
| TimerOptions(options.t1_init_timeout, |
| TimerBackoffAlgorithm::kExponential, |
| options.max_init_retransmits))), |
| t1_cookie_(timer_manager_.CreateTimer( |
| "t1-cookie", |
| [this]() { return OnCookieTimerExpiry(); }, |
| TimerOptions(options.t1_cookie_timeout, |
| TimerBackoffAlgorithm::kExponential, |
| options.max_init_retransmits))), |
| t2_shutdown_(timer_manager_.CreateTimer( |
| "t2-shutdown", |
| [this]() { return OnShutdownTimerExpiry(); }, |
| TimerOptions(options.t2_shutdown_timeout, |
| TimerBackoffAlgorithm::kExponential, |
| options.max_retransmissions))), |
| send_queue_( |
| log_prefix_, |
| options_.max_send_buffer_size, |
| [this](StreamID stream_id) { |
| callbacks_.OnBufferedAmountLow(stream_id); |
| }, |
| options_.total_buffered_amount_low_threshold, |
| [this]() { callbacks_.OnTotalBufferedAmountLow(); }) {} |
| |
| std::string DcSctpSocket::log_prefix() const { |
| return log_prefix_ + "[" + std::string(ToString(state_)) + "] "; |
| } |
| |
| bool DcSctpSocket::IsConsistent() const { |
| 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() && |
| cookie_echo_chunk_.has_value()); |
| 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); |
| SendPacket(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() { |
| 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()); |
| callbacks_.TriggerDeferred(); |
| } |
| |
| void DcSctpSocket::Shutdown() { |
| 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()); |
| callbacks_.TriggerDeferred(); |
| } |
| |
| void DcSctpSocket::Close() { |
| 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())); |
| SendPacket(b); |
| } |
| InternalClose(ErrorKind::kNoError, ""); |
| } else { |
| RTC_DLOG(LS_INFO) << log_prefix() << "Called Close on a closed socket"; |
| } |
| RTC_DCHECK(IsConsistent()); |
| callbacks_.TriggerDeferred(); |
| } |
| |
| void DcSctpSocket::CloseConnectionBecauseOfTooManyTransmissionErrors() { |
| SendPacket(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; |
| cookie_echo_chunk_ = absl::nullopt; |
| |
| 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()); |
| } |
| |
| SendStatus DcSctpSocket::Send(DcSctpMessage message, |
| const SendOptions& send_options) { |
| if (message.payload().empty()) { |
| callbacks_.OnError(ErrorKind::kProtocolViolation, |
| "Unable to send empty message"); |
| return SendStatus::kErrorMessageEmpty; |
| } |
| if (message.payload().size() > options_.max_message_size) { |
| 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." |
| callbacks_.OnError(ErrorKind::kWrongSequence, |
| "Unable to send message as the socket is shutting down"); |
| return SendStatus::kErrorShuttingDown; |
| } |
| if (send_queue_.IsFull()) { |
| callbacks_.OnError(ErrorKind::kResourceExhaustion, |
| "Unable to send message as the send queue is full"); |
| return SendStatus::kErrorResourceExhaustion; |
| } |
| |
| TimeMs now = callbacks_.TimeMillis(); |
| send_queue_.Add(now, std::move(message), send_options); |
| if (tcb_ != nullptr) { |
| tcb_->SendBufferedPackets(now); |
| } |
| |
| RTC_DCHECK(IsConsistent()); |
| callbacks_.TriggerDeferred(); |
| return SendStatus::kSuccess; |
| } |
| |
| ResetStreamsStatus DcSctpSocket::ResetStreams( |
| rtc::ArrayView<const StreamID> outgoing_streams) { |
| 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); |
| absl::optional<ReConfigChunk> reconfig = |
| tcb_->stream_reset_handler().MakeStreamResetRequest(); |
| if (reconfig.has_value()) { |
| SctpPacket::Builder builder = tcb_->PacketBuilder(); |
| builder.Add(*reconfig); |
| SendPacket(builder); |
| } |
| |
| RTC_DCHECK(IsConsistent()); |
| callbacks_.TriggerDeferred(); |
| return ResetStreamsStatus::kPerformed; |
| } |
| |
| SocketState DcSctpSocket::state() const { |
| switch (state_) { |
| case State::kClosed: |
| return SocketState::kClosed; |
| case State::kCookieWait: |
| ABSL_FALLTHROUGH_INTENDED; |
| case State::kCookieEchoed: |
| return SocketState::kConnecting; |
| case State::kEstablished: |
| return SocketState::kConnected; |
| case State::kShutdownPending: |
| ABSL_FALLTHROUGH_INTENDED; |
| case State::kShutdownSent: |
| ABSL_FALLTHROUGH_INTENDED; |
| case State::kShutdownReceived: |
| ABSL_FALLTHROUGH_INTENDED; |
| case State::kShutdownAckSent: |
| return SocketState::kShuttingDown; |
| } |
| } |
| |
| void DcSctpSocket::SetMaxMessageSize(size_t max_message_size) { |
| options_.max_message_size = max_message_size; |
| } |
| |
| size_t DcSctpSocket::buffered_amount(StreamID stream_id) const { |
| return send_queue_.buffered_amount(stream_id); |
| } |
| |
| size_t DcSctpSocket::buffered_amount_low_threshold(StreamID stream_id) const { |
| return send_queue_.buffered_amount_low_threshold(stream_id); |
| } |
| |
| void DcSctpSocket::SetBufferedAmountLowThreshold(StreamID stream_id, |
| size_t bytes) { |
| send_queue_.SetBufferedAmountLowThreshold(stream_id, bytes); |
| } |
| |
| 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(); |
| } |
| } |
| } |
| |
| 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) { |
| 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()); |
| callbacks_.TriggerDeferred(); |
| } |
| |
| void DcSctpSocket::ReceivePacket(rtc::ArrayView<const uint8_t> data) { |
| 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()); |
| callbacks_.TriggerDeferred(); |
| 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()); |
| callbacks_.TriggerDeferred(); |
| 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()); |
| callbacks_.TriggerDeferred(); |
| } |
| |
| 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: |
| HandleForwardTsn(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. |
| SendPacket(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; |
| 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; |
| |
| RTC_DCHECK(state_ == State::kCookieEchoed); |
| |
| if (t1_cookie_->is_running()) { |
| SendCookieEcho(); |
| } 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; |
| |
| 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..." |
| |
| SendPacket(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::SendPacket(SctpPacket::Builder& builder) { |
| if (builder.empty()) { |
| return; |
| } |
| |
| std::vector<uint8_t> payload = builder.Build(); |
| |
| if (RTC_DLOG_IS_ON) { |
| DebugPrintOutgoing(payload); |
| } |
| |
| // 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(); |
| } |
| |
| if (packet_observer_ != nullptr) { |
| packet_observer_->OnSentPacket(callbacks_.TimeMillis(), payload); |
| } |
| callbacks_.SendPacket(payload); |
| } |
| |
| 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. |
| SendPacket(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. |
| SendPacket(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; |
| } |
| |
| tcb_->data_tracker().Observe(tsn, immediate_ack); |
| tcb_->reassembly_queue().MaybeResetStreamsDeferred( |
| tcb_->data_tracker().last_cumulative_acked_tsn()); |
| tcb_->reassembly_queue().Add(tsn, std::move(data)); |
| 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." |
| |
| SendPacket(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 = GetCapabilities(options_, 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); |
| SendPacket(b); |
| } |
| |
| void DcSctpSocket::SendCookieEcho() { |
| RTC_DCHECK(tcb_ != nullptr); |
| TimeMs now = callbacks_.TimeMillis(); |
| SctpPacket::Builder b = tcb_->PacketBuilder(); |
| b.Add(*cookie_echo_chunk_); |
| |
| // https://tools.ietf.org/html/rfc4960#section-5.1 |
| // "The COOKIE ECHO chunk can be bundled with any pending outbound DATA |
| // chunks, but it MUST be the first chunk in the packet and until the COOKIE |
| // ACK is returned the sender MUST NOT send any other packets to the peer." |
| tcb_->SendBufferedPackets(b, now, /*only_one_packet=*/true); |
| } |
| |
| 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()) { |
| SendPacket(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 = GetCapabilities(options_, chunk->parameters()); |
| t1_init_->Stop(); |
| |
| tcb_ = std::make_unique<TransmissionControlBlock>( |
| timer_manager_, log_prefix_, options_, capabilities, callbacks_, |
| send_queue_, connect_params_.verification_tag, |
| connect_params_.initial_tsn, chunk->initiate_tag(), chunk->initial_tsn(), |
| chunk->a_rwnd(), MakeTieTag(callbacks_), |
| [this]() { return state_ == State::kEstablished; }, |
| [this](SctpPacket::Builder& builder) { return SendPacket(builder); }); |
| RTC_DLOG(LS_VERBOSE) << log_prefix() |
| << "Created peer TCB: " << tcb_->ToString(); |
| |
| SetState(State::kCookieEchoed, "INIT_ACK received"); |
| |
| // The connection isn't fully established just yet. |
| cookie_echo_chunk_ = CookieEchoChunk(cookie->data()); |
| SendCookieEcho(); |
| 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) { |
| cookie_echo_chunk_ = absl::nullopt; |
| SetState(State::kEstablished, "COOKIE_ECHO received"); |
| callbacks_.OnConnected(); |
| } |
| |
| if (tcb_ == nullptr) { |
| tcb_ = std::make_unique<TransmissionControlBlock>( |
| timer_manager_, log_prefix_, options_, cookie->capabilities(), |
| callbacks_, send_queue_, connect_params_.verification_tag, |
| connect_params_.initial_tsn, cookie->initiate_tag(), |
| cookie->initial_tsn(), cookie->a_rwnd(), MakeTieTag(callbacks_), |
| [this]() { return state_ == State::kEstablished; }, |
| [this](SctpPacket::Builder& builder) { return SendPacket(builder); }); |
| RTC_DLOG(LS_VERBOSE) << log_prefix() |
| << "Created peer TCB: " << tcb_->ToString(); |
| } |
| |
| 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())); |
| SendPacket(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"; |
| |
| // If a message was partly sent, and the peer restarted, resend it in |
| // full by resetting the send queue. |
| send_queue_.Reset(); |
| 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(); |
| cookie_echo_chunk_ = absl::nullopt; |
| 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()) { |
| 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 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) { |
| absl::optional<ReConfigChunk> chunk = ReConfigChunk::Parse(descriptor.data); |
| if (ValidateParseSuccess(chunk) && ValidateHasTCB()) { |
| tcb_->stream_reset_handler().HandleReConfig(*std::move(chunk)); |
| } |
| } |
| |
| 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)); |
| SendPacket(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)); |
| SendPacket(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())); |
| SendPacket(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())); |
| SendPacket(b); |
| } |
| |
| void DcSctpSocket::SendShutdownAck() { |
| SendPacket(tcb_->PacketBuilder().Add(ShutdownAckChunk())); |
| t2_shutdown_->set_duration(tcb_->current_rto()); |
| t2_shutdown_->Start(); |
| } |
| |
| } // namespace dcsctp |