1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
/*
* 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/functional/bind_front.h"
#include "absl/strings/string_view.h"
#include "api/task_queue/task_queue_base.h"
#include "net/dcsctp/common/sequence_numbers.h"
#include "net/dcsctp/packet/chunk/cookie_echo_chunk.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/packet_sender.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,
PacketSender& packet_sender,
std::function<bool()> is_connection_established);
// 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(webrtc::TimeDelta rtt) override;
webrtc::TimeDelta 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 {
packet_sender_.Send(builder,
/*write_checksum=*/!capabilities_.zero_checksum);
}
// 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_; }
size_t cwnd() const { return retransmission_queue_.cwnd(); }
webrtc::TimeDelta current_srtt() const { return rto_.srtt(); }
// 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();
// Sends a FORWARD-TSN, if it is needed and allowed (rate-limited).
void MaybeSendForwardTsn(SctpPacket::Builder& builder, webrtc::Timestamp now);
// Will be set while the socket is in kCookieEcho state. In this state, there
// can only be a single packet outstanding, and it must contain the COOKIE
// ECHO chunk as the first chunk in that packet, until the COOKIE ACK has been
// received, which will make the socket call `ClearCookieEchoChunk`.
void SetCookieEchoChunk(CookieEchoChunk chunk) {
cookie_echo_chunk_ = std::move(chunk);
}
// Called when the COOKIE ACK chunk has been received, to allow further
// packets to be sent.
void ClearCookieEchoChunk() { cookie_echo_chunk_ = absl::nullopt; }
bool has_cookie_echo_chunk() const { return cookie_echo_chunk_.has_value(); }
void MaybeSendFastRetransmit();
// Fills `builder` (which may already be filled with control chunks) with
// other control and data chunks, and sends packets as much as can be
// allowed by the congestion control algorithm.
void SendBufferedPackets(SctpPacket::Builder& builder, webrtc::Timestamp now);
// As above, but without passing in a builder. If `cookie_echo_chunk_` is
// present, then only one packet will be sent, with this chunk as the first
// chunk.
void SendBufferedPackets(webrtc::Timestamp now) {
SctpPacket::Builder builder(peer_verification_tag_, options_);
SendBufferedPackets(builder, now);
}
// Returns a textual representation of this object, for logging.
std::string ToString() const;
HandoverReadinessStatus GetHandoverReadiness() const;
void AddHandoverState(DcSctpSocketHandoverState& state);
void RestoreFromState(const DcSctpSocketHandoverState& handover_state);
private:
// Will be called when the retransmission timer (t3-rtx) expires.
webrtc::TimeDelta OnRtxTimerExpiry();
// Will be called when the delayed ack timer expires.
webrtc::TimeDelta OnDelayedAckTimerExpiry();
const absl::string_view 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_;
PacketSender& packet_sender_;
// Rate limiting of FORWARD-TSN. Next can be sent at or after this timestamp.
webrtc::Timestamp limit_forward_tsn_until_ = webrtc::Timestamp::Zero();
RetransmissionTimeout rto_;
RetransmissionErrorCounter tx_error_counter_;
DataTracker data_tracker_;
ReassemblyQueue reassembly_queue_;
RetransmissionQueue retransmission_queue_;
StreamResetHandler stream_reset_handler_;
HeartbeatHandler heartbeat_handler_;
// Only valid when the socket state == State::kCookieEchoed. In this state,
// the socket must wait for COOKIE ACK to continue sending any packets (not
// including a COOKIE ECHO). So if `cookie_echo_chunk_` is present, the
// SendBufferedChunks will always only just send one packet, with this chunk
// as the first chunk in the packet.
absl::optional<CookieEchoChunk> cookie_echo_chunk_ = absl::nullopt;
};
} // namespace dcsctp
#endif // NET_DCSCTP_SOCKET_TRANSMISSION_CONTROL_BLOCK_H_
|
