diff options
Diffstat (limited to 'net/dcsctp/socket/transmission_control_block.cc')
| -rw-r--r-- | net/dcsctp/socket/transmission_control_block.cc | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/net/dcsctp/socket/transmission_control_block.cc b/net/dcsctp/socket/transmission_control_block.cc new file mode 100644 index 0000000000..4fde40cee9 --- /dev/null +++ b/net/dcsctp/socket/transmission_control_block.cc @@ -0,0 +1,168 @@ +/* + * 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/transmission_control_block.h" + +#include <algorithm> +#include <cstdint> +#include <memory> +#include <string> +#include <utility> +#include <vector> + +#include "absl/types/optional.h" +#include "net/dcsctp/packet/chunk/data_chunk.h" +#include "net/dcsctp/packet/chunk/forward_tsn_chunk.h" +#include "net/dcsctp/packet/chunk/idata_chunk.h" +#include "net/dcsctp/packet/chunk/iforward_tsn_chunk.h" +#include "net/dcsctp/packet/chunk/reconfig_chunk.h" +#include "net/dcsctp/packet/chunk/sack_chunk.h" +#include "net/dcsctp/packet/sctp_packet.h" +#include "net/dcsctp/public/dcsctp_options.h" +#include "net/dcsctp/rx/data_tracker.h" +#include "net/dcsctp/rx/reassembly_queue.h" +#include "net/dcsctp/socket/capabilities.h" +#include "net/dcsctp/socket/stream_reset_handler.h" +#include "net/dcsctp/timer/timer.h" +#include "net/dcsctp/tx/retransmission_queue.h" +#include "net/dcsctp/tx/retransmission_timeout.h" +#include "rtc_base/logging.h" +#include "rtc_base/strings/string_builder.h" + +namespace dcsctp { + +void TransmissionControlBlock::ObserveRTT(DurationMs rtt) { + DurationMs prev_rto = rto_.rto(); + rto_.ObserveRTT(rtt); + RTC_DLOG(LS_VERBOSE) << log_prefix_ << "new rtt=" << *rtt + << ", srtt=" << *rto_.srtt() << ", rto=" << *rto_.rto() + << " (" << *prev_rto << ")"; + t3_rtx_->set_duration(rto_.rto()); + + DurationMs delayed_ack_tmo = + std::min(rto_.rto() * 0.5, options_.delayed_ack_max_timeout); + delayed_ack_timer_->set_duration(delayed_ack_tmo); +} + +absl::optional<DurationMs> TransmissionControlBlock::OnRtxTimerExpiry() { + TimeMs now = callbacks_.TimeMillis(); + RTC_DLOG(LS_INFO) << log_prefix_ << "Timer " << t3_rtx_->name() + << " has expired"; + if (cookie_echo_chunk_.has_value()) { + // In the COOKIE_ECHO state, let the T1-COOKIE timer trigger + // retransmissions, to avoid having two timers doing that. + RTC_DLOG(LS_VERBOSE) << "Not retransmitting as T1-cookie is active."; + } else { + if (IncrementTxErrorCounter("t3-rtx expired")) { + retransmission_queue_.HandleT3RtxTimerExpiry(); + SendBufferedPackets(now); + } + } + return absl::nullopt; +} + +absl::optional<DurationMs> TransmissionControlBlock::OnDelayedAckTimerExpiry() { + data_tracker_.HandleDelayedAckTimerExpiry(); + MaybeSendSack(); + return absl::nullopt; +} + +void TransmissionControlBlock::MaybeSendSack() { + if (data_tracker_.ShouldSendAck(/*also_if_delayed=*/false)) { + SctpPacket::Builder builder = PacketBuilder(); + builder.Add( + data_tracker_.CreateSelectiveAck(reassembly_queue_.remaining_bytes())); + Send(builder); + } +} + +void TransmissionControlBlock::SendBufferedPackets(SctpPacket::Builder& builder, + TimeMs now) { + for (int packet_idx = 0;; ++packet_idx) { + // Only add control chunks to the first packet that is sent, if sending + // multiple packets in one go (as allowed by the congestion window). + if (packet_idx == 0) { + if (cookie_echo_chunk_.has_value()) { + // 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..." + RTC_DCHECK(builder.empty()); + builder.Add(*cookie_echo_chunk_); + } + + // https://tools.ietf.org/html/rfc4960#section-6 + // "Before an endpoint transmits a DATA chunk, if any received DATA + // chunks have not been acknowledged (e.g., due to delayed ack), the + // sender should create a SACK and bundle it with the outbound DATA chunk, + // as long as the size of the final SCTP packet does not exceed the + // current MTU." + if (data_tracker_.ShouldSendAck(/*also_if_delayed=*/true)) { + builder.Add(data_tracker_.CreateSelectiveAck( + reassembly_queue_.remaining_bytes())); + } + if (retransmission_queue_.ShouldSendForwardTsn(now)) { + if (capabilities_.message_interleaving) { + builder.Add(retransmission_queue_.CreateIForwardTsn()); + } else { + builder.Add(retransmission_queue_.CreateForwardTsn()); + } + } + absl::optional<ReConfigChunk> reconfig = + stream_reset_handler_.MakeStreamResetRequest(); + if (reconfig.has_value()) { + builder.Add(*reconfig); + } + } + + auto chunks = + retransmission_queue_.GetChunksToSend(now, builder.bytes_remaining()); + for (auto& elem : chunks) { + TSN tsn = elem.first; + Data data = std::move(elem.second); + if (capabilities_.message_interleaving) { + builder.Add(IDataChunk(tsn, std::move(data), false)); + } else { + builder.Add(DataChunk(tsn, std::move(data), false)); + } + } + if (builder.empty()) { + break; + } + Send(builder); + + if (cookie_echo_chunk_.has_value()) { + // https://tools.ietf.org/html/rfc4960#section-5.1 + // "... until the COOKIE ACK is returned the sender MUST NOT send any + // other packets to the peer." + break; + } + } +} + +std::string TransmissionControlBlock::ToString() const { + rtc::StringBuilder sb; + + sb.AppendFormat( + "verification_tag=%08x, last_cumulative_ack=%u, capabilities=", + *peer_verification_tag_, *data_tracker_.last_cumulative_acked_tsn()); + + if (capabilities_.partial_reliability) { + sb << "PR,"; + } + if (capabilities_.message_interleaving) { + sb << "IL,"; + } + if (capabilities_.reconfig) { + sb << "Reconfig,"; + } + + return sb.Release(); +} + +} // namespace dcsctp |