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
|
/*
* 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/packet/chunk/sack_chunk.h"
#include <stddef.h>
#include <cstdint>
#include <optional>
#include <string>
#include <type_traits>
#include <vector>
#include "api/array_view.h"
#include "net/dcsctp/packet/bounded_byte_reader.h"
#include "net/dcsctp/packet/bounded_byte_writer.h"
#include "net/dcsctp/packet/tlv_trait.h"
#include "rtc_base/logging.h"
#include "rtc_base/strings/str_join.h"
#include "rtc_base/strings/string_builder.h"
namespace dcsctp {
// https://tools.ietf.org/html/rfc4960#section-3.3.4
// 0 1 2 3
// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Type = 3 |Chunk Flags | Chunk Length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Cumulative TSN Ack |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Advertised Receiver Window Credit (a_rwnd) |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Number of Gap Ack Blocks = N | Number of Duplicate TSNs = X |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Gap Ack Block #1 Start | Gap Ack Block #1 End |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// / /
// \ ... \
// / /
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Gap Ack Block #N Start | Gap Ack Block #N End |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Duplicate TSN 1 |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// / /
// \ ... \
// / /
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Duplicate TSN X |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
constexpr int SackChunk::kType;
std::optional<SackChunk> SackChunk::Parse(
webrtc::ArrayView<const uint8_t> data) {
std::optional<BoundedByteReader<kHeaderSize>> reader = ParseTLV(data);
if (!reader.has_value()) {
return std::nullopt;
}
TSN tsn_ack(reader->Load32<4>());
uint32_t a_rwnd = reader->Load32<8>();
uint16_t nbr_of_gap_blocks = reader->Load16<12>();
uint16_t nbr_of_dup_tsns = reader->Load16<14>();
if (reader->variable_data_size() != nbr_of_gap_blocks * kGapAckBlockSize +
nbr_of_dup_tsns * kDupTsnBlockSize) {
RTC_DLOG(LS_WARNING) << "Invalid number of gap blocks or duplicate TSNs";
return std::nullopt;
}
std::vector<GapAckBlock> gap_ack_blocks;
gap_ack_blocks.reserve(nbr_of_gap_blocks);
size_t offset = 0;
for (int i = 0; i < nbr_of_gap_blocks; ++i) {
BoundedByteReader<kGapAckBlockSize> sub_reader =
reader->sub_reader<kGapAckBlockSize>(offset);
uint16_t start = sub_reader.Load16<0>();
uint16_t end = sub_reader.Load16<2>();
gap_ack_blocks.emplace_back(start, end);
offset += kGapAckBlockSize;
}
std::set<TSN> duplicate_tsns;
for (int i = 0; i < nbr_of_dup_tsns; ++i) {
BoundedByteReader<kDupTsnBlockSize> sub_reader =
reader->sub_reader<kDupTsnBlockSize>(offset);
duplicate_tsns.insert(TSN(sub_reader.Load32<0>()));
offset += kDupTsnBlockSize;
}
RTC_DCHECK(offset == reader->variable_data_size());
return SackChunk(tsn_ack, a_rwnd, gap_ack_blocks, duplicate_tsns);
}
void SackChunk::SerializeTo(std::vector<uint8_t>& out) const {
int nbr_of_gap_blocks = gap_ack_blocks_.size();
int nbr_of_dup_tsns = duplicate_tsns_.size();
size_t variable_size =
nbr_of_gap_blocks * kGapAckBlockSize + nbr_of_dup_tsns * kDupTsnBlockSize;
BoundedByteWriter<kHeaderSize> writer = AllocateTLV(out, variable_size);
writer.Store32<4>(*cumulative_tsn_ack_);
writer.Store32<8>(a_rwnd_);
writer.Store16<12>(nbr_of_gap_blocks);
writer.Store16<14>(nbr_of_dup_tsns);
size_t offset = 0;
for (int i = 0; i < nbr_of_gap_blocks; ++i) {
BoundedByteWriter<kGapAckBlockSize> sub_writer =
writer.sub_writer<kGapAckBlockSize>(offset);
sub_writer.Store16<0>(gap_ack_blocks_[i].start);
sub_writer.Store16<2>(gap_ack_blocks_[i].end);
offset += kGapAckBlockSize;
}
for (TSN tsn : duplicate_tsns_) {
BoundedByteWriter<kDupTsnBlockSize> sub_writer =
writer.sub_writer<kDupTsnBlockSize>(offset);
sub_writer.Store32<0>(*tsn);
offset += kDupTsnBlockSize;
}
RTC_DCHECK(offset == variable_size);
}
std::string SackChunk::ToString() const {
webrtc::StringBuilder sb;
sb << "SACK, cum_ack_tsn=" << *cumulative_tsn_ack()
<< ", a_rwnd=" << a_rwnd();
for (const GapAckBlock& gap : gap_ack_blocks_) {
uint32_t first = *cumulative_tsn_ack_ + gap.start;
uint32_t last = *cumulative_tsn_ack_ + gap.end;
sb << ", gap=" << first << "--" << last;
}
if (!duplicate_tsns_.empty()) {
sb << ", dup_tsns="
<< webrtc::StrJoin(
duplicate_tsns(), ",",
[](webrtc::StringBuilder& sb, TSN tsn) { sb << *tsn; });
}
return sb.Release();
}
} // namespace dcsctp
|
