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/*
* 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.
*/
#ifndef NET_DCSCTP_SOCKET_TRANSMISSION_CONTROL_BLOCK_H_
#define NET_DCSCTP_SOCKET_TRANSMISSION_CONTROL_BLOCK_H_
#include <cstdint>
#include <functional>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "absl/strings/string_view.h"
#include "net/dcsctp/common/sequence_numbers.h"
#include "net/dcsctp/packet/sctp_packet.h"
#include "net/dcsctp/public/dcsctp_options.h"
#include "net/dcsctp/public/dcsctp_socket.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/context.h"
#include "net/dcsctp/socket/heartbeat_handler.h"
#include "net/dcsctp/socket/stream_reset_handler.h"
#include "net/dcsctp/timer/timer.h"
#include "net/dcsctp/tx/retransmission_error_counter.h"
#include "net/dcsctp/tx/retransmission_queue.h"
#include "net/dcsctp/tx/retransmission_timeout.h"
#include "net/dcsctp/tx/send_queue.h"
namespace dcsctp {
// The TransmissionControlBlock (TCB) represents an open connection to a peer,
// and holds all the resources for that. If the connection is e.g. shutdown,
// closed or restarted, this object will be deleted and/or replaced.
class TransmissionControlBlock : public Context {
public:
TransmissionControlBlock(TimerManager& timer_manager,
absl::string_view log_prefix,
const DcSctpOptions& options,
const Capabilities& capabilities,
DcSctpSocketCallbacks& callbacks,
SendQueue& send_queue,
VerificationTag my_verification_tag,
TSN my_initial_tsn,
VerificationTag peer_verification_tag,
TSN peer_initial_tsn,
size_t a_rwnd,
TieTag tie_tag,
std::function<bool()> is_connection_established,
std::function<void(SctpPacket::Builder&)> send_fn)
: log_prefix_(log_prefix),
options_(options),
timer_manager_(timer_manager),
capabilities_(capabilities),
callbacks_(callbacks),
t3_rtx_(timer_manager_.CreateTimer(
"t3-rtx",
[this]() { return OnRtxTimerExpiry(); },
TimerOptions(options.rto_initial))),
delayed_ack_timer_(timer_manager_.CreateTimer(
"delayed-ack",
[this]() { return OnDelayedAckTimerExpiry(); },
TimerOptions(options.delayed_ack_max_timeout,
TimerBackoffAlgorithm::kExponential,
/*max_restarts=*/0))),
my_verification_tag_(my_verification_tag),
my_initial_tsn_(my_initial_tsn),
peer_verification_tag_(peer_verification_tag),
peer_initial_tsn_(peer_initial_tsn),
tie_tag_(tie_tag),
is_connection_established_(std::move(is_connection_established)),
send_fn_(std::move(send_fn)),
rto_(options),
tx_error_counter_(log_prefix, options),
data_tracker_(log_prefix, delayed_ack_timer_.get(), peer_initial_tsn),
reassembly_queue_(log_prefix,
peer_initial_tsn,
options.max_receiver_window_buffer_size),
retransmission_queue_(
log_prefix,
my_initial_tsn,
a_rwnd,
send_queue,
[this](DurationMs rtt) { return ObserveRTT(rtt); },
[this]() { callbacks_.NotifyOutgoingMessageBufferEmpty(); },
[this]() { tx_error_counter_.Clear(); },
*t3_rtx_,
options,
capabilities.partial_reliability,
capabilities.message_interleaving),
stream_reset_handler_(log_prefix,
this,
&timer_manager,
&data_tracker_,
&reassembly_queue_,
&retransmission_queue_),
heartbeat_handler_(log_prefix, options, this, &timer_manager_) {}
// Implementation of `Context`.
bool is_connection_established() const override {
return is_connection_established_();
}
TSN my_initial_tsn() const override { return my_initial_tsn_; }
TSN peer_initial_tsn() const override { return peer_initial_tsn_; }
DcSctpSocketCallbacks& callbacks() const override { return callbacks_; }
void ObserveRTT(DurationMs rtt) override;
DurationMs current_rto() const override { return rto_.rto(); }
bool IncrementTxErrorCounter(absl::string_view reason) override {
return tx_error_counter_.Increment(reason);
}
void ClearTxErrorCounter() override { tx_error_counter_.Clear(); }
SctpPacket::Builder PacketBuilder() const override {
return SctpPacket::Builder(peer_verification_tag_, options_);
}
bool HasTooManyTxErrors() const override {
return tx_error_counter_.IsExhausted();
}
void Send(SctpPacket::Builder& builder) override { send_fn_(builder); }
// Other accessors
DataTracker& data_tracker() { return data_tracker_; }
ReassemblyQueue& reassembly_queue() { return reassembly_queue_; }
RetransmissionQueue& retransmission_queue() { return retransmission_queue_; }
StreamResetHandler& stream_reset_handler() { return stream_reset_handler_; }
HeartbeatHandler& heartbeat_handler() { return heartbeat_handler_; }
// Returns this socket's verification tag, set in all packet headers.
VerificationTag my_verification_tag() const { return my_verification_tag_; }
// Returns the peer's verification tag, which should be in received packets.
VerificationTag peer_verification_tag() const {
return peer_verification_tag_;
}
// All negotiated supported capabilities.
const Capabilities& capabilities() const { return capabilities_; }
// A 64-bit tie-tag, used to e.g. detect reconnections.
TieTag tie_tag() const { return tie_tag_; }
// Sends a SACK, if there is a need to.
void MaybeSendSack();
// Fills `builder` (which may already be filled with control chunks) with
// with other control and data chunks, and sends packets as much as can be
// allowed by the congestion control algorithm. If `only_one_packet` is true,
// only a single packet will be sent. Otherwise, zero, one or multiple may be
// sent.
void SendBufferedPackets(SctpPacket::Builder& builder,
bool only_one_packet = false);
// As above, but without passing in a builder and allowing sending many
// packets.
void SendBufferedPackets() {
SctpPacket::Builder builder(peer_verification_tag_, options_);
SendBufferedPackets(builder, /*only_one_packet=*/false);
}
// Returns a textual representation of this object, for logging.
std::string ToString() const;
private:
// Will be called when the retransmission timer (t3-rtx) expires.
absl::optional<DurationMs> OnRtxTimerExpiry();
// Will be called when the delayed ack timer expires.
absl::optional<DurationMs> OnDelayedAckTimerExpiry();
const std::string log_prefix_;
const DcSctpOptions options_;
TimerManager& timer_manager_;
// Negotiated capabilities that both peers support.
const Capabilities capabilities_;
DcSctpSocketCallbacks& callbacks_;
// The data retransmission timer, called t3-rtx in SCTP.
const std::unique_ptr<Timer> t3_rtx_;
// Delayed ack timer, which triggers when acks should be sent (when delayed).
const std::unique_ptr<Timer> delayed_ack_timer_;
const VerificationTag my_verification_tag_;
const TSN my_initial_tsn_;
const VerificationTag peer_verification_tag_;
const TSN peer_initial_tsn_;
// Nonce, used to detect reconnections.
const TieTag tie_tag_;
const std::function<bool()> is_connection_established_;
const std::function<void(SctpPacket::Builder&)> send_fn_;
RetransmissionTimeout rto_;
RetransmissionErrorCounter tx_error_counter_;
DataTracker data_tracker_;
ReassemblyQueue reassembly_queue_;
RetransmissionQueue retransmission_queue_;
StreamResetHandler stream_reset_handler_;
HeartbeatHandler heartbeat_handler_;
};
} // namespace dcsctp
#endif // NET_DCSCTP_SOCKET_TRANSMISSION_CONTROL_BLOCK_H_