1 /* 2 * Copyright (c) 2021 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 #include "net/dcsctp/packet/chunk/forward_tsn_chunk.h" 11 12 #include <stddef.h> 13 #include <stdint.h> 14 15 #include <string> 16 #include <utility> 17 #include <vector> 18 19 #include "absl/types/optional.h" 20 #include "api/array_view.h" 21 #include "net/dcsctp/packet/bounded_byte_reader.h" 22 #include "net/dcsctp/packet/bounded_byte_writer.h" 23 #include "net/dcsctp/packet/chunk/forward_tsn_common.h" 24 #include "net/dcsctp/packet/tlv_trait.h" 25 #include "rtc_base/strings/string_builder.h" 26 27 namespace dcsctp { 28 29 // https://tools.ietf.org/html/rfc3758#section-3.2 30 31 // 0 1 2 3 32 // 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 33 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 34 // | Type = 192 | Flags = 0x00 | Length = Variable | 35 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 36 // | New Cumulative TSN | 37 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 38 // | Stream-1 | Stream Sequence-1 | 39 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 40 // \ / 41 // / \ 42 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 43 // | Stream-N | Stream Sequence-N | 44 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 45 constexpr int ForwardTsnChunk::kType; 46 Parse(rtc::ArrayView<const uint8_t> data)47absl::optional<ForwardTsnChunk> ForwardTsnChunk::Parse( 48 rtc::ArrayView<const uint8_t> data) { 49 absl::optional<BoundedByteReader<kHeaderSize>> reader = ParseTLV(data); 50 if (!reader.has_value()) { 51 return absl::nullopt; 52 } 53 TSN new_cumulative_tsn(reader->Load32<4>()); 54 55 size_t streams_skipped = 56 reader->variable_data_size() / kSkippedStreamBufferSize; 57 58 std::vector<SkippedStream> skipped_streams; 59 skipped_streams.reserve(streams_skipped); 60 for (size_t i = 0; i < streams_skipped; ++i) { 61 BoundedByteReader<kSkippedStreamBufferSize> sub_reader = 62 reader->sub_reader<kSkippedStreamBufferSize>(i * 63 kSkippedStreamBufferSize); 64 65 StreamID stream_id(sub_reader.Load16<0>()); 66 SSN ssn(sub_reader.Load16<2>()); 67 skipped_streams.emplace_back(stream_id, ssn); 68 } 69 return ForwardTsnChunk(new_cumulative_tsn, std::move(skipped_streams)); 70 } 71 SerializeTo(std::vector<uint8_t> & out) const72void ForwardTsnChunk::SerializeTo(std::vector<uint8_t>& out) const { 73 rtc::ArrayView<const SkippedStream> skipped = skipped_streams(); 74 size_t variable_size = skipped.size() * kSkippedStreamBufferSize; 75 BoundedByteWriter<kHeaderSize> writer = AllocateTLV(out, variable_size); 76 77 writer.Store32<4>(*new_cumulative_tsn()); 78 for (size_t i = 0; i < skipped.size(); ++i) { 79 BoundedByteWriter<kSkippedStreamBufferSize> sub_writer = 80 writer.sub_writer<kSkippedStreamBufferSize>(i * 81 kSkippedStreamBufferSize); 82 sub_writer.Store16<0>(*skipped[i].stream_id); 83 sub_writer.Store16<2>(*skipped[i].ssn); 84 } 85 } 86 ToString() const87std::string ForwardTsnChunk::ToString() const { 88 rtc::StringBuilder sb; 89 sb << "FORWARD-TSN, new_cumulative_tsn=" << *new_cumulative_tsn(); 90 for (const auto& skipped : skipped_streams()) { 91 sb << ", skip " << skipped.stream_id.value() << ":" << *skipped.ssn; 92 } 93 return sb.str(); 94 } 95 } // namespace dcsctp 96