| /* |
| * 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/rx/reassembly_queue.h" |
| |
| #include <stddef.h> |
| |
| #include <algorithm> |
| #include <cstdint> |
| #include <memory> |
| #include <set> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include "absl/strings/string_view.h" |
| #include "absl/types/optional.h" |
| #include "api/array_view.h" |
| #include "net/dcsctp/common/sequence_numbers.h" |
| #include "net/dcsctp/common/str_join.h" |
| #include "net/dcsctp/packet/chunk/forward_tsn_common.h" |
| #include "net/dcsctp/packet/data.h" |
| #include "net/dcsctp/packet/parameter/outgoing_ssn_reset_request_parameter.h" |
| #include "net/dcsctp/packet/parameter/reconfiguration_response_parameter.h" |
| #include "net/dcsctp/public/dcsctp_message.h" |
| #include "net/dcsctp/rx/reassembly_streams.h" |
| #include "net/dcsctp/rx/traditional_reassembly_streams.h" |
| #include "rtc_base/logging.h" |
| |
| namespace dcsctp { |
| ReassemblyQueue::ReassemblyQueue( |
| absl::string_view log_prefix, |
| TSN peer_initial_tsn, |
| size_t max_size_bytes, |
| const DcSctpSocketHandoverState* handover_state) |
| : log_prefix_(std::string(log_prefix) + "reasm: "), |
| max_size_bytes_(max_size_bytes), |
| watermark_bytes_(max_size_bytes * kHighWatermarkLimit), |
| last_assembled_tsn_watermark_(tsn_unwrapper_.Unwrap( |
| handover_state ? TSN(handover_state->rx.last_assembled_tsn) |
| : TSN(*peer_initial_tsn - 1))), |
| last_completed_reset_req_seq_nbr_( |
| handover_state |
| ? ReconfigRequestSN( |
| handover_state->rx.last_completed_deferred_reset_req_sn) |
| : ReconfigRequestSN(0)), |
| streams_(std::make_unique<TraditionalReassemblyStreams>( |
| log_prefix_, |
| [this](rtc::ArrayView<const UnwrappedTSN> tsns, |
| DcSctpMessage message) { |
| AddReassembledMessage(tsns, std::move(message)); |
| }, |
| handover_state)) {} |
| |
| void ReassemblyQueue::Add(TSN tsn, Data data) { |
| RTC_DCHECK(IsConsistent()); |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "added tsn=" << *tsn |
| << ", stream=" << *data.stream_id << ":" |
| << *data.message_id << ":" << *data.fsn << ", type=" |
| << (data.is_beginning && data.is_end |
| ? "complete" |
| : data.is_beginning |
| ? "first" |
| : data.is_end ? "last" : "middle"); |
| |
| UnwrappedTSN unwrapped_tsn = tsn_unwrapper_.Unwrap(tsn); |
| |
| if (unwrapped_tsn <= last_assembled_tsn_watermark_ || |
| delivered_tsns_.find(unwrapped_tsn) != delivered_tsns_.end()) { |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ |
| << "Chunk has already been delivered - skipping"; |
| return; |
| } |
| |
| // If a stream reset has been received with a "sender's last assigned tsn" in |
| // the future, the socket is in "deferred reset processing" mode and must |
| // buffer chunks until it's exited. |
| if (deferred_reset_streams_.has_value() && |
| unwrapped_tsn > |
| tsn_unwrapper_.Unwrap( |
| deferred_reset_streams_->req.sender_last_assigned_tsn())) { |
| RTC_DLOG(LS_VERBOSE) |
| << log_prefix_ << "Deferring chunk with tsn=" << *tsn |
| << " until cum_ack_tsn=" |
| << *deferred_reset_streams_->req.sender_last_assigned_tsn(); |
| // https://tools.ietf.org/html/rfc6525#section-5.2.2 |
| // "In this mode, any data arriving with a TSN larger than the |
| // Sender's Last Assigned TSN for the affected stream(s) MUST be queued |
| // locally and held until the cumulative acknowledgment point reaches the |
| // Sender's Last Assigned TSN." |
| queued_bytes_ += data.size(); |
| deferred_reset_streams_->deferred_chunks.emplace_back( |
| std::make_pair(tsn, std::move(data))); |
| } else { |
| queued_bytes_ += streams_->Add(unwrapped_tsn, std::move(data)); |
| } |
| |
| // https://tools.ietf.org/html/rfc4960#section-6.9 |
| // "Note: If the data receiver runs out of buffer space while still |
| // waiting for more fragments to complete the reassembly of the message, it |
| // should dispatch part of its inbound message through a partial delivery |
| // API (see Section 10), freeing some of its receive buffer space so that |
| // the rest of the message may be received." |
| |
| // TODO(boivie): Support EOR flag and partial delivery? |
| RTC_DCHECK(IsConsistent()); |
| } |
| |
| ReconfigurationResponseParameter::Result ReassemblyQueue::ResetStreams( |
| const OutgoingSSNResetRequestParameter& req, |
| TSN cum_tsn_ack) { |
| RTC_DCHECK(IsConsistent()); |
| if (deferred_reset_streams_.has_value()) { |
| // In deferred mode already. |
| return ReconfigurationResponseParameter::Result::kInProgress; |
| } else if (req.request_sequence_number() <= |
| last_completed_reset_req_seq_nbr_) { |
| // Already performed at some time previously. |
| return ReconfigurationResponseParameter::Result::kSuccessPerformed; |
| } |
| |
| UnwrappedTSN sla_tsn = tsn_unwrapper_.Unwrap(req.sender_last_assigned_tsn()); |
| UnwrappedTSN unwrapped_cum_tsn_ack = tsn_unwrapper_.Unwrap(cum_tsn_ack); |
| |
| // https://tools.ietf.org/html/rfc6525#section-5.2.2 |
| // "If the Sender's Last Assigned TSN is greater than the |
| // cumulative acknowledgment point, then the endpoint MUST enter "deferred |
| // reset processing"." |
| if (sla_tsn > unwrapped_cum_tsn_ack) { |
| RTC_DLOG(LS_VERBOSE) |
| << log_prefix_ |
| << "Entering deferred reset processing mode until cum_tsn_ack=" |
| << *req.sender_last_assigned_tsn(); |
| deferred_reset_streams_ = absl::make_optional<DeferredResetStreams>(req); |
| return ReconfigurationResponseParameter::Result::kInProgress; |
| } |
| |
| // https://tools.ietf.org/html/rfc6525#section-5.2.2 |
| // "... streams MUST be reset to 0 as the next expected SSN." |
| streams_->ResetStreams(req.stream_ids()); |
| last_completed_reset_req_seq_nbr_ = req.request_sequence_number(); |
| RTC_DCHECK(IsConsistent()); |
| return ReconfigurationResponseParameter::Result::kSuccessPerformed; |
| } |
| |
| bool ReassemblyQueue::MaybeResetStreamsDeferred(TSN cum_ack_tsn) { |
| RTC_DCHECK(IsConsistent()); |
| if (deferred_reset_streams_.has_value()) { |
| UnwrappedTSN unwrapped_cum_ack_tsn = tsn_unwrapper_.Unwrap(cum_ack_tsn); |
| UnwrappedTSN unwrapped_sla_tsn = tsn_unwrapper_.Unwrap( |
| deferred_reset_streams_->req.sender_last_assigned_tsn()); |
| if (unwrapped_cum_ack_tsn >= unwrapped_sla_tsn) { |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ |
| << "Leaving deferred reset processing with tsn=" |
| << *cum_ack_tsn << ", feeding back " |
| << deferred_reset_streams_->deferred_chunks.size() |
| << " chunks"; |
| // https://tools.ietf.org/html/rfc6525#section-5.2.2 |
| // "... streams MUST be reset to 0 as the next expected SSN." |
| streams_->ResetStreams(deferred_reset_streams_->req.stream_ids()); |
| std::vector<std::pair<TSN, Data>> deferred_chunks = |
| std::move(deferred_reset_streams_->deferred_chunks); |
| // The response will not be sent now, but as a reply to the retried |
| // request, which will come as "in progress" has been sent prior. |
| last_completed_reset_req_seq_nbr_ = |
| deferred_reset_streams_->req.request_sequence_number(); |
| deferred_reset_streams_ = absl::nullopt; |
| |
| // https://tools.ietf.org/html/rfc6525#section-5.2.2 |
| // "Any queued TSNs (queued at step E2) MUST now be released and processed |
| // normally." |
| for (auto& [tsn, data] : deferred_chunks) { |
| queued_bytes_ -= data.size(); |
| Add(tsn, std::move(data)); |
| } |
| |
| RTC_DCHECK(IsConsistent()); |
| return true; |
| } else { |
| RTC_DLOG(LS_VERBOSE) << "Staying in deferred reset processing. tsn=" |
| << *cum_ack_tsn; |
| } |
| } |
| |
| return false; |
| } |
| |
| std::vector<DcSctpMessage> ReassemblyQueue::FlushMessages() { |
| std::vector<DcSctpMessage> ret; |
| reassembled_messages_.swap(ret); |
| return ret; |
| } |
| |
| void ReassemblyQueue::AddReassembledMessage( |
| rtc::ArrayView<const UnwrappedTSN> tsns, |
| DcSctpMessage message) { |
| RTC_DLOG(LS_VERBOSE) << log_prefix_ << "Assembled message from TSN=[" |
| << StrJoin(tsns, ",", |
| [](rtc::StringBuilder& sb, UnwrappedTSN tsn) { |
| sb << *tsn.Wrap(); |
| }) |
| << "], message; stream_id=" << *message.stream_id() |
| << ", ppid=" << *message.ppid() |
| << ", payload=" << message.payload().size() << " bytes"; |
| |
| for (const UnwrappedTSN tsn : tsns) { |
| if (tsn <= last_assembled_tsn_watermark_) { |
| // This can be provoked by a misbehaving peer by sending FORWARD-TSN with |
| // invalid SSNs, allowing ordered messages to stay in the queue that |
| // should've been discarded. |
| RTC_DLOG(LS_VERBOSE) |
| << log_prefix_ |
| << "Message is built from fragments already seen - skipping"; |
| return; |
| } else if (tsn == last_assembled_tsn_watermark_.next_value()) { |
| // Update watermark, or insert into delivered_tsns_ |
| last_assembled_tsn_watermark_.Increment(); |
| } else { |
| delivered_tsns_.insert(tsn); |
| } |
| } |
| |
| // With new TSNs in delivered_tsns, gaps might be filled. |
| MaybeMoveLastAssembledWatermarkFurther(); |
| |
| reassembled_messages_.emplace_back(std::move(message)); |
| } |
| |
| void ReassemblyQueue::MaybeMoveLastAssembledWatermarkFurther() { |
| // `delivered_tsns_` contain TSNS when there is a gap between ranges of |
| // assembled TSNs. `last_assembled_tsn_watermark_` should not be adjacent to |
| // that list, because if so, it can be moved. |
| while (!delivered_tsns_.empty() && |
| *delivered_tsns_.begin() == |
| last_assembled_tsn_watermark_.next_value()) { |
| last_assembled_tsn_watermark_.Increment(); |
| delivered_tsns_.erase(delivered_tsns_.begin()); |
| } |
| } |
| |
| void ReassemblyQueue::Handle(const AnyForwardTsnChunk& forward_tsn) { |
| RTC_DCHECK(IsConsistent()); |
| UnwrappedTSN tsn = tsn_unwrapper_.Unwrap(forward_tsn.new_cumulative_tsn()); |
| |
| last_assembled_tsn_watermark_ = std::max(last_assembled_tsn_watermark_, tsn); |
| delivered_tsns_.erase(delivered_tsns_.begin(), |
| delivered_tsns_.upper_bound(tsn)); |
| |
| MaybeMoveLastAssembledWatermarkFurther(); |
| |
| queued_bytes_ -= |
| streams_->HandleForwardTsn(tsn, forward_tsn.skipped_streams()); |
| RTC_DCHECK(IsConsistent()); |
| } |
| |
| bool ReassemblyQueue::IsConsistent() const { |
| // `delivered_tsns_` and `last_assembled_tsn_watermark_` mustn't overlap or be |
| // adjacent. |
| if (!delivered_tsns_.empty() && |
| last_assembled_tsn_watermark_.next_value() >= *delivered_tsns_.begin()) { |
| return false; |
| } |
| |
| // Allow queued_bytes_ to be larger than max_size_bytes, as it's not actively |
| // enforced in this class. This comparison will still trigger if queued_bytes_ |
| // became "negative". |
| return (queued_bytes_ >= 0 && queued_bytes_ <= 2 * max_size_bytes_); |
| } |
| |
| HandoverReadinessStatus ReassemblyQueue::GetHandoverReadiness() const { |
| HandoverReadinessStatus status = streams_->GetHandoverReadiness(); |
| if (!delivered_tsns_.empty()) { |
| status.Add(HandoverUnreadinessReason::kReassemblyQueueDeliveredTSNsGap); |
| } |
| if (deferred_reset_streams_.has_value()) { |
| status.Add(HandoverUnreadinessReason::kStreamResetDeferred); |
| } |
| return status; |
| } |
| |
| void ReassemblyQueue::AddHandoverState(DcSctpSocketHandoverState& state) { |
| state.rx.last_assembled_tsn = last_assembled_tsn_watermark_.Wrap().value(); |
| state.rx.last_completed_deferred_reset_req_sn = |
| last_completed_reset_req_seq_nbr_.value(); |
| streams_->AddHandoverState(state); |
| } |
| |
| } // namespace dcsctp |
