| /* |
| * 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 (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, |
| bool only_one_packet) { |
| 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) { |
| // 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 (only_one_packet) { |
| 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 |