| /* |
| * 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/tx/retransmission_queue.h" |
| |
| #include <algorithm> |
| #include <cstdint> |
| #include <functional> |
| #include <iterator> |
| #include <map> |
| #include <optional> |
| #include <set> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include "absl/algorithm/container.h" |
| #include "absl/strings/string_view.h" |
| #include "api/array_view.h" |
| #include "net/dcsctp/common/math.h" |
| #include "net/dcsctp/common/sequence_numbers.h" |
| #include "net/dcsctp/packet/chunk/data_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/idata_chunk.h" |
| #include "net/dcsctp/packet/chunk/iforward_tsn_chunk.h" |
| #include "net/dcsctp/packet/chunk/sack_chunk.h" |
| #include "net/dcsctp/packet/data.h" |
| #include "net/dcsctp/public/dcsctp_options.h" |
| #include "net/dcsctp/public/types.h" |
| #include "net/dcsctp/timer/timer.h" |
| #include "net/dcsctp/tx/outstanding_data.h" |
| #include "net/dcsctp/tx/send_queue.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/logging.h" |
| #include "rtc_base/strings/str_join.h" |
| #include "rtc_base/strings/string_builder.h" |
| |
| namespace dcsctp { |
| namespace { |
| using ::webrtc::TimeDelta; |
| using ::webrtc::Timestamp; |
| } // namespace |
| |
| RetransmissionQueue::RetransmissionQueue( |
| absl::string_view log_prefix, |
| DcSctpSocketCallbacks* callbacks, |
| TSN my_initial_tsn, |
| size_t a_rwnd, |
| SendQueue& send_queue, |
| std::function<void(TimeDelta rtt)> on_new_rtt, |
| std::function<void()> on_clear_retransmission_counter, |
| Timer& t3_rtx, |
| const DcSctpOptions& options, |
| bool supports_partial_reliability, |
| bool use_message_interleaving) |
| : callbacks_(*callbacks), |
| options_(options), |
| partial_reliability_(supports_partial_reliability), |
| log_prefix_(log_prefix), |
| data_chunk_header_size_(use_message_interleaving |
| ? IDataChunk::kHeaderSize |
| : DataChunk::kHeaderSize), |
| on_new_rtt_(std::move(on_new_rtt)), |
| on_clear_retransmission_counter_( |
| std::move(on_clear_retransmission_counter)), |
| t3_rtx_(t3_rtx), |
| cwnd_(options_.cwnd_mtus_initial * options_.mtu), |
| rwnd_(a_rwnd), |
| // https://tools.ietf.org/html/rfc4960#section-7.2.1 |
| // "The initial value of ssthresh MAY be arbitrarily high (for |
| // example, implementations MAY use the size of the receiver advertised |
| // window)."" |
| ssthresh_(rwnd_), |
| partial_bytes_acked_(0), |
| send_queue_(send_queue), |
| outstanding_data_( |
| data_chunk_header_size_, |
| tsn_unwrapper_.Unwrap(TSN(*my_initial_tsn - 1)), |
| [this](StreamID stream_id, OutgoingMessageId message_id) { |
| return send_queue_.Discard(stream_id, message_id); |
| }) {} |
| |
| bool RetransmissionQueue::IsConsistent() const { |
| return true; |
| } |
| |
| // Returns how large a chunk will be, serialized, carrying the data |
| size_t RetransmissionQueue::GetSerializedChunkSize(const Data& data) const { |
| return RoundUpTo4(data_chunk_header_size_ + data.size()); |
| } |
| |
| void RetransmissionQueue::MaybeExitFastRecovery( |
| UnwrappedTSN cumulative_tsn_ack) { |
| // https://tools.ietf.org/html/rfc4960#section-7.2.4 |
| // "When a SACK acknowledges all TSNs up to and including this [fast |
| // recovery] exit point, Fast Recovery is exited." |
| if (fast_recovery_exit_tsn_.has_value() && |
| cumulative_tsn_ack >= *fast_recovery_exit_tsn_) { |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ |
| << "exit_point=" << *fast_recovery_exit_tsn_->Wrap() |
| << " reached - exiting fast recovery"; |
| fast_recovery_exit_tsn_ = std::nullopt; |
| } |
| } |
| |
| void RetransmissionQueue::HandleIncreasedCumulativeTsnAck( |
| size_t unacked_bytes, |
| size_t total_bytes_acked) { |
| // Allow some margin for classifying as fully utilized, due to e.g. that too |
| // small packets (less than kMinimumFragmentedPayload) are not sent + |
| // overhead. |
| bool is_fully_utilized = unacked_bytes + options_.mtu >= cwnd_; |
| size_t old_cwnd = cwnd_; |
| if (phase() == CongestionAlgorithmPhase::kSlowStart) { |
| if (is_fully_utilized && !is_in_fast_recovery()) { |
| // https://tools.ietf.org/html/rfc4960#section-7.2.1 |
| // "Only when these three conditions are met can the cwnd be |
| // increased; otherwise, the cwnd MUST not be increased. If these |
| // conditions are met, then cwnd MUST be increased by, at most, the |
| // lesser of 1) the total size of the previously outstanding DATA |
| // chunk(s) acknowledged, and 2) the destination's path MTU." |
| cwnd_ += std::min(total_bytes_acked, options_.mtu); |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "SS increase cwnd=" << cwnd_ |
| << " (" << old_cwnd << ")"; |
| } |
| } else if (phase() == CongestionAlgorithmPhase::kCongestionAvoidance) { |
| // https://tools.ietf.org/html/rfc4960#section-7.2.2 |
| // "Whenever cwnd is greater than ssthresh, upon each SACK arrival |
| // that advances the Cumulative TSN Ack Point, increase |
| // partial_bytes_acked by the total number of bytes of all new chunks |
| // acknowledged in that SACK including chunks acknowledged by the new |
| // Cumulative TSN Ack and by Gap Ack Blocks." |
| size_t old_pba = partial_bytes_acked_; |
| partial_bytes_acked_ += total_bytes_acked; |
| |
| if (partial_bytes_acked_ >= cwnd_ && is_fully_utilized) { |
| // https://tools.ietf.org/html/rfc4960#section-7.2.2 |
| // "When partial_bytes_acked is equal to or greater than cwnd and |
| // before the arrival of the SACK the sender had cwnd or more bytes of |
| // data outstanding (i.e., before arrival of the SACK, flightsize was |
| // greater than or equal to cwnd), increase cwnd by MTU, and reset |
| // partial_bytes_acked to (partial_bytes_acked - cwnd)." |
| |
| // Errata: https://datatracker.ietf.org/doc/html/rfc8540#section-3.12 |
| partial_bytes_acked_ -= cwnd_; |
| cwnd_ += options_.mtu; |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "CA increase cwnd=" << cwnd_ |
| << " (" << old_cwnd << ") ssthresh=" << ssthresh_ |
| << ", pba=" << partial_bytes_acked_ << " (" |
| << old_pba << ")"; |
| } else { |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "CA unchanged cwnd=" << cwnd_ |
| << " (" << old_cwnd << ") ssthresh=" << ssthresh_ |
| << ", pba=" << partial_bytes_acked_ << " (" |
| << old_pba << ")"; |
| } |
| } |
| } |
| |
| void RetransmissionQueue::HandlePacketLoss( |
| UnwrappedTSN /* highest_tsn_acked */) { |
| if (!is_in_fast_recovery()) { |
| // https://tools.ietf.org/html/rfc4960#section-7.2.4 |
| // "If not in Fast Recovery, adjust the ssthresh and cwnd of the |
| // destination address(es) to which the missing DATA chunks were last |
| // sent, according to the formula described in Section 7.2.3." |
| size_t old_cwnd = cwnd_; |
| size_t old_pba = partial_bytes_acked_; |
| ssthresh_ = std::max(cwnd_ / 2, options_.cwnd_mtus_min * options_.mtu); |
| cwnd_ = ssthresh_; |
| partial_bytes_acked_ = 0; |
| |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ |
| << "packet loss detected (not fast recovery). cwnd=" |
| << cwnd_ << " (" << old_cwnd |
| << "), ssthresh=" << ssthresh_ |
| << ", pba=" << partial_bytes_acked_ << " (" << old_pba |
| << ")"; |
| |
| // https://tools.ietf.org/html/rfc4960#section-7.2.4 |
| // "If not in Fast Recovery, enter Fast Recovery and mark the highest |
| // outstanding TSN as the Fast Recovery exit point." |
| fast_recovery_exit_tsn_ = outstanding_data_.highest_outstanding_tsn(); |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ |
| << "fast recovery initiated with exit_point=" |
| << *fast_recovery_exit_tsn_->Wrap(); |
| } else { |
| // https://tools.ietf.org/html/rfc4960#section-7.2.4 |
| // "While in Fast Recovery, the ssthresh and cwnd SHOULD NOT change for |
| // any destinations due to a subsequent Fast Recovery event (i.e., one |
| // SHOULD NOT reduce the cwnd further due to a subsequent Fast Retransmit)." |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ |
| << "packet loss detected (fast recovery). No changes."; |
| } |
| } |
| |
| void RetransmissionQueue::UpdateReceiverWindow(uint32_t a_rwnd) { |
| rwnd_ = outstanding_data_.unacked_bytes() >= a_rwnd |
| ? 0 |
| : a_rwnd - outstanding_data_.unacked_bytes(); |
| } |
| |
| void RetransmissionQueue::StartT3RtxTimerIfOutstandingData() { |
| // Note: Can't use `unacked_bytes()` as that one doesn't count chunks to |
| // be retransmitted. |
| if (outstanding_data_.empty()) { |
| // https://tools.ietf.org/html/rfc4960#section-6.3.2 |
| // "Whenever all outstanding data sent to an address have been |
| // acknowledged, turn off the T3-rtx timer of that address. |
| // Note: Already stopped in `StopT3RtxTimerOnIncreasedCumulativeTsnAck`." |
| } else { |
| // https://tools.ietf.org/html/rfc4960#section-6.3.2 |
| // "Whenever a SACK is received that acknowledges the DATA chunk |
| // with the earliest outstanding TSN for that address, restart the T3-rtx |
| // timer for that address with its current RTO (if there is still |
| // outstanding data on that address)." |
| // "Whenever a SACK is received missing a TSN that was previously |
| // acknowledged via a Gap Ack Block, start the T3-rtx for the destination |
| // address to which the DATA chunk was originally transmitted if it is not |
| // already running." |
| if (!t3_rtx_.is_running()) { |
| t3_rtx_.Start(); |
| } |
| } |
| } |
| |
| bool RetransmissionQueue::IsSackValid(const SackChunk& sack) const { |
| // https://tools.ietf.org/html/rfc4960#section-6.2.1 |
| // "If Cumulative TSN Ack is less than the Cumulative TSN Ack Point, |
| // then drop the SACK. Since Cumulative TSN Ack is monotonically increasing, |
| // a SACK whose Cumulative TSN Ack is less than the Cumulative TSN Ack Point |
| // indicates an out-of- order SACK." |
| // |
| // Note: Important not to drop SACKs with identical TSN to that previously |
| // received, as the gap ack blocks or dup tsn fields may have changed. |
| UnwrappedTSN cumulative_tsn_ack = |
| tsn_unwrapper_.PeekUnwrap(sack.cumulative_tsn_ack()); |
| if (cumulative_tsn_ack < outstanding_data_.last_cumulative_tsn_ack()) { |
| // https://tools.ietf.org/html/rfc4960#section-6.2.1 |
| // "If Cumulative TSN Ack is less than the Cumulative TSN Ack Point, |
| // then drop the SACK. Since Cumulative TSN Ack is monotonically |
| // increasing, a SACK whose Cumulative TSN Ack is less than the Cumulative |
| // TSN Ack Point indicates an out-of- order SACK." |
| return false; |
| } else if (cumulative_tsn_ack > outstanding_data_.highest_outstanding_tsn()) { |
| return false; |
| } |
| return true; |
| } |
| |
| bool RetransmissionQueue::HandleSack(Timestamp now, const SackChunk& sack) { |
| if (!IsSackValid(sack)) { |
| return false; |
| } |
| |
| UnwrappedTSN old_last_cumulative_tsn_ack = |
| outstanding_data_.last_cumulative_tsn_ack(); |
| size_t old_unacked_bytes = outstanding_data_.unacked_bytes(); |
| size_t old_rwnd = rwnd_; |
| UnwrappedTSN cumulative_tsn_ack = |
| tsn_unwrapper_.Unwrap(sack.cumulative_tsn_ack()); |
| |
| if (sack.gap_ack_blocks().empty()) { |
| UpdateRTT(now, cumulative_tsn_ack); |
| } |
| |
| // Exit fast recovery before continuing processing, in case it needs to go |
| // into fast recovery again due to new reported packet loss. |
| MaybeExitFastRecovery(cumulative_tsn_ack); |
| |
| OutstandingData::AckInfo ack_info = outstanding_data_.HandleSack( |
| cumulative_tsn_ack, sack.gap_ack_blocks(), is_in_fast_recovery()); |
| |
| // Add lifecycle events for delivered messages. |
| for (LifecycleId lifecycle_id : ack_info.acked_lifecycle_ids) { |
| RTC_DLOG(LS_VERBOSE) << "Triggering OnLifecycleMessageDelivered(" |
| << lifecycle_id.value() << ")"; |
| callbacks_.OnLifecycleMessageDelivered(lifecycle_id); |
| callbacks_.OnLifecycleEnd(lifecycle_id); |
| } |
| for (LifecycleId lifecycle_id : ack_info.abandoned_lifecycle_ids) { |
| RTC_DLOG(LS_VERBOSE) << "Triggering OnLifecycleMessageExpired(" |
| << lifecycle_id.value() << ", true)"; |
| callbacks_.OnLifecycleMessageExpired(lifecycle_id, |
| /*maybe_delivered=*/true); |
| callbacks_.OnLifecycleEnd(lifecycle_id); |
| } |
| |
| // Update of outstanding_data_ is now done. Congestion control remains. |
| UpdateReceiverWindow(sack.a_rwnd()); |
| |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "Received SACK, cum_tsn_ack=" |
| << *cumulative_tsn_ack.Wrap() << " (" |
| << *old_last_cumulative_tsn_ack.Wrap() |
| << "), unacked_bytes=" |
| << outstanding_data_.unacked_bytes() << " (" |
| << old_unacked_bytes << "), rwnd=" << rwnd_ << " (" |
| << old_rwnd << ")"; |
| |
| if (cumulative_tsn_ack > old_last_cumulative_tsn_ack) { |
| // https://tools.ietf.org/html/rfc4960#section-6.3.2 |
| // "Whenever a SACK is received that acknowledges the DATA chunk |
| // with the earliest outstanding TSN for that address, restart the T3-rtx |
| // timer for that address with its current RTO (if there is still |
| // outstanding data on that address)." |
| // Note: It may be started again in a bit further down. |
| t3_rtx_.Stop(); |
| |
| HandleIncreasedCumulativeTsnAck(old_unacked_bytes, ack_info.bytes_acked); |
| } |
| |
| if (ack_info.has_packet_loss) { |
| HandlePacketLoss(ack_info.highest_tsn_acked); |
| } |
| |
| // https://tools.ietf.org/html/rfc4960#section-8.2 |
| // "When an outstanding TSN is acknowledged [...] the endpoint shall clear |
| // the error counter ..." |
| if (ack_info.bytes_acked > 0) { |
| on_clear_retransmission_counter_(); |
| } |
| |
| StartT3RtxTimerIfOutstandingData(); |
| RTC_DCHECK(IsConsistent()); |
| return true; |
| } |
| |
| void RetransmissionQueue::UpdateRTT(Timestamp now, |
| UnwrappedTSN cumulative_tsn_ack) { |
| // RTT updating is flawed in SCTP, as explained in e.g. Pedersen J, Griwodz C, |
| // Halvorsen P (2006) Considerations of SCTP retransmission delays for thin |
| // streams. |
| // Due to delayed acknowledgement, the SACK may be sent much later which |
| // increases the calculated RTT. |
| // TODO(boivie): Consider occasionally sending DATA chunks with I-bit set and |
| // use only those packets for measurement. |
| |
| TimeDelta rtt = outstanding_data_.MeasureRTT(now, cumulative_tsn_ack); |
| |
| if (rtt.IsFinite()) { |
| on_new_rtt_(rtt); |
| } |
| } |
| |
| void RetransmissionQueue::HandleT3RtxTimerExpiry() { |
| size_t old_cwnd = cwnd_; |
| size_t old_unacked_bytes = unacked_bytes(); |
| // https://tools.ietf.org/html/rfc4960#section-6.3.3 |
| // "For the destination address for which the timer expires, adjust |
| // its ssthresh with rules defined in Section 7.2.3 and set the cwnd <- MTU." |
| ssthresh_ = std::max(cwnd_ / 2, 4 * options_.mtu); |
| cwnd_ = 1 * options_.mtu; |
| // Errata: https://datatracker.ietf.org/doc/html/rfc8540#section-3.11 |
| partial_bytes_acked_ = 0; |
| |
| // https://tools.ietf.org/html/rfc4960#section-6.3.3 |
| // "For the destination address for which the timer expires, set RTO |
| // <- RTO * 2 ("back off the timer"). The maximum value discussed in rule C7 |
| // above (RTO.max) may be used to provide an upper bound to this doubling |
| // operation." |
| |
| // Already done by the Timer implementation. |
| |
| // https://tools.ietf.org/html/rfc4960#section-6.3.3 |
| // "Determine how many of the earliest (i.e., lowest TSN) outstanding |
| // DATA chunks for the address for which the T3-rtx has expired will fit into |
| // a single packet" |
| |
| // https://tools.ietf.org/html/rfc4960#section-6.3.3 |
| // "Note: Any DATA chunks that were sent to the address for which the |
| // T3-rtx timer expired but did not fit in one MTU (rule E3 above) should be |
| // marked for retransmission and sent as soon as cwnd allows (normally, when a |
| // SACK arrives)." |
| outstanding_data_.NackAll(); |
| |
| // https://tools.ietf.org/html/rfc4960#section-6.3.3 |
| // "Start the retransmission timer T3-rtx on the destination address |
| // to which the retransmission is sent, if rule R1 above indicates to do so." |
| |
| // Already done by the Timer implementation. |
| |
| RTC_DLOG(LS_INFO) << log_prefix_ << "t3-rtx expired. new cwnd=" << cwnd_ |
| << " (" << old_cwnd << "), ssthresh=" << ssthresh_ |
| << ", unacked_bytes " << unacked_bytes() << " (" |
| << old_unacked_bytes << ")"; |
| RTC_DCHECK(IsConsistent()); |
| } |
| |
| std::vector<std::pair<TSN, Data>> |
| RetransmissionQueue::GetChunksForFastRetransmit(size_t bytes_in_packet) { |
| RTC_DCHECK(outstanding_data_.has_data_to_be_fast_retransmitted()); |
| RTC_DCHECK(IsDivisibleBy4(bytes_in_packet)); |
| std::vector<std::pair<TSN, Data>> to_be_sent; |
| size_t old_unacked_bytes = unacked_bytes(); |
| |
| to_be_sent = |
| outstanding_data_.GetChunksToBeFastRetransmitted(bytes_in_packet); |
| RTC_DCHECK(!to_be_sent.empty()); |
| |
| // https://tools.ietf.org/html/rfc4960#section-7.2.4 |
| // "4) Restart the T3-rtx timer only if ... the endpoint is retransmitting |
| // the first outstanding DATA chunk sent to that address." |
| if (to_be_sent[0].first == |
| outstanding_data_.last_cumulative_tsn_ack().next_value().Wrap()) { |
| RTC_DLOG(LS_VERBOSE) |
| << log_prefix_ |
| << "First outstanding DATA to be retransmitted - restarting T3-RTX"; |
| t3_rtx_.Stop(); |
| } |
| |
| // https://tools.ietf.org/html/rfc4960#section-6.3.2 |
| // "Every time a DATA chunk is sent to any address (including a |
| // retransmission), if the T3-rtx timer of that address is not running, |
| // start it running so that it will expire after the RTO of that address." |
| if (!t3_rtx_.is_running()) { |
| t3_rtx_.Start(); |
| } |
| |
| size_t bytes_retransmitted = absl::c_accumulate( |
| to_be_sent, 0, [&](size_t r, const std::pair<TSN, Data>& d) { |
| return r + GetSerializedChunkSize(d.second); |
| }); |
| ++rtx_packets_count_; |
| rtx_bytes_count_ += bytes_retransmitted; |
| |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "Fast-retransmitting TSN " |
| << webrtc::StrJoin(to_be_sent, ",", |
| [&](rtc::StringBuilder& sb, |
| const std::pair<TSN, Data>& c) { |
| sb << *c.first; |
| }) |
| << " - " << bytes_retransmitted |
| << " bytes. unacked_bytes=" << unacked_bytes() << " (" |
| << old_unacked_bytes << ")"; |
| |
| RTC_DCHECK(IsConsistent()); |
| return to_be_sent; |
| } |
| |
| std::vector<std::pair<TSN, Data>> RetransmissionQueue::GetChunksToSend( |
| Timestamp now, |
| size_t bytes_remaining_in_packet) { |
| // Chunks are always padded to even divisible by four. |
| RTC_DCHECK(IsDivisibleBy4(bytes_remaining_in_packet)); |
| |
| std::vector<std::pair<TSN, Data>> to_be_sent; |
| size_t old_unacked_bytes = unacked_bytes(); |
| size_t old_rwnd = rwnd_; |
| |
| // Calculate the bandwidth budget (how many bytes that is |
| // allowed to be sent), and fill that up first with chunks that are |
| // scheduled to be retransmitted. If there is still budget, send new chunks |
| // (which will have their TSN assigned here.) |
| size_t max_bytes = |
| RoundDownTo4(std::min(max_bytes_to_send(), bytes_remaining_in_packet)); |
| |
| to_be_sent = outstanding_data_.GetChunksToBeRetransmitted(max_bytes); |
| |
| size_t bytes_retransmitted = absl::c_accumulate( |
| to_be_sent, 0, [&](size_t r, const std::pair<TSN, Data>& d) { |
| return r + GetSerializedChunkSize(d.second); |
| }); |
| max_bytes -= bytes_retransmitted; |
| |
| if (!to_be_sent.empty()) { |
| ++rtx_packets_count_; |
| rtx_bytes_count_ += bytes_retransmitted; |
| } |
| |
| while (max_bytes > data_chunk_header_size_) { |
| RTC_DCHECK(IsDivisibleBy4(max_bytes)); |
| std::optional<SendQueue::DataToSend> chunk_opt = |
| send_queue_.Produce(now, max_bytes - data_chunk_header_size_); |
| if (!chunk_opt.has_value()) { |
| break; |
| } |
| |
| size_t chunk_size = GetSerializedChunkSize(chunk_opt->data); |
| max_bytes -= chunk_size; |
| rwnd_ -= chunk_size; |
| |
| std::optional<UnwrappedTSN> tsn = outstanding_data_.Insert( |
| chunk_opt->message_id, chunk_opt->data, now, |
| partial_reliability_ ? chunk_opt->max_retransmissions |
| : MaxRetransmits::NoLimit(), |
| partial_reliability_ ? chunk_opt->expires_at |
| : Timestamp::PlusInfinity(), |
| chunk_opt->lifecycle_id); |
| |
| if (tsn.has_value()) { |
| if (chunk_opt->lifecycle_id.IsSet()) { |
| RTC_DCHECK(chunk_opt->data.is_end); |
| callbacks_.OnLifecycleMessageFullySent(chunk_opt->lifecycle_id); |
| } |
| to_be_sent.emplace_back(tsn->Wrap(), std::move(chunk_opt->data)); |
| } |
| } |
| |
| if (!to_be_sent.empty()) { |
| // https://tools.ietf.org/html/rfc4960#section-6.3.2 |
| // "Every time a DATA chunk is sent to any address (including a |
| // retransmission), if the T3-rtx timer of that address is not running, |
| // start it running so that it will expire after the RTO of that address." |
| if (!t3_rtx_.is_running()) { |
| t3_rtx_.Start(); |
| } |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "Sending TSN " |
| << webrtc::StrJoin(to_be_sent, ",", |
| [&](rtc::StringBuilder& sb, |
| const std::pair<TSN, Data>& c) { |
| sb << *c.first; |
| }) |
| << " - " |
| << absl::c_accumulate( |
| to_be_sent, 0, |
| [&](size_t r, const std::pair<TSN, Data>& d) { |
| return r + GetSerializedChunkSize(d.second); |
| }) |
| << " bytes. unacked_bytes=" << unacked_bytes() << " (" |
| << old_unacked_bytes << "), cwnd=" << cwnd_ |
| << ", rwnd=" << rwnd_ << " (" << old_rwnd << ")"; |
| } |
| RTC_DCHECK(IsConsistent()); |
| return to_be_sent; |
| } |
| |
| bool RetransmissionQueue::ShouldSendForwardTsn(Timestamp now) { |
| if (!partial_reliability_) { |
| return false; |
| } |
| outstanding_data_.ExpireOutstandingChunks(now); |
| bool ret = outstanding_data_.ShouldSendForwardTsn(); |
| RTC_DCHECK(IsConsistent()); |
| return ret; |
| } |
| |
| size_t RetransmissionQueue::max_bytes_to_send() const { |
| size_t left = unacked_bytes() >= cwnd_ ? 0 : cwnd_ - unacked_bytes(); |
| |
| if (unacked_bytes() == 0) { |
| // https://datatracker.ietf.org/doc/html/rfc4960#section-6.1 |
| // ... However, regardless of the value of rwnd (including if it is 0), the |
| // data sender can always have one DATA chunk in flight to the receiver if |
| // allowed by cwnd (see rule B, below). |
| return left; |
| } |
| |
| return std::min(rwnd(), left); |
| } |
| |
| void RetransmissionQueue::PrepareResetStream(StreamID stream_id) { |
| // TODO(boivie): These calls are now only affecting the send queue. The |
| // packet buffer can also change behavior - for example draining the chunk |
| // producer and eagerly assign TSNs so that an "Outgoing SSN Reset Request" |
| // can be sent quickly, with a known `sender_last_assigned_tsn`. |
| send_queue_.PrepareResetStream(stream_id); |
| } |
| bool RetransmissionQueue::HasStreamsReadyToBeReset() const { |
| return send_queue_.HasStreamsReadyToBeReset(); |
| } |
| std::vector<StreamID> RetransmissionQueue::BeginResetStreams() { |
| outstanding_data_.BeginResetStreams(); |
| return send_queue_.GetStreamsReadyToBeReset(); |
| } |
| void RetransmissionQueue::CommitResetStreams() { |
| send_queue_.CommitResetStreams(); |
| } |
| void RetransmissionQueue::RollbackResetStreams() { |
| send_queue_.RollbackResetStreams(); |
| } |
| |
| HandoverReadinessStatus RetransmissionQueue::GetHandoverReadiness() const { |
| HandoverReadinessStatus status; |
| if (!outstanding_data_.empty()) { |
| status.Add(HandoverUnreadinessReason::kRetransmissionQueueOutstandingData); |
| } |
| if (fast_recovery_exit_tsn_.has_value()) { |
| status.Add(HandoverUnreadinessReason::kRetransmissionQueueFastRecovery); |
| } |
| if (outstanding_data_.has_data_to_be_retransmitted()) { |
| status.Add(HandoverUnreadinessReason::kRetransmissionQueueNotEmpty); |
| } |
| return status; |
| } |
| |
| void RetransmissionQueue::AddHandoverState(DcSctpSocketHandoverState& state) { |
| state.tx.next_tsn = next_tsn().value(); |
| state.tx.rwnd = rwnd_; |
| state.tx.cwnd = cwnd_; |
| state.tx.ssthresh = ssthresh_; |
| state.tx.partial_bytes_acked = partial_bytes_acked_; |
| } |
| |
| void RetransmissionQueue::RestoreFromState( |
| const DcSctpSocketHandoverState& state) { |
| // Validate that the component is in pristine state. |
| RTC_DCHECK(outstanding_data_.empty()); |
| RTC_DCHECK(!t3_rtx_.is_running()); |
| RTC_DCHECK(partial_bytes_acked_ == 0); |
| |
| cwnd_ = state.tx.cwnd; |
| rwnd_ = state.tx.rwnd; |
| ssthresh_ = state.tx.ssthresh; |
| partial_bytes_acked_ = state.tx.partial_bytes_acked; |
| |
| outstanding_data_.ResetSequenceNumbers( |
| tsn_unwrapper_.Unwrap(TSN(state.tx.next_tsn - 1))); |
| } |
| } // namespace dcsctp |
