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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.
*/
#include "net/dcsctp/packet/chunk/forward_tsn_chunk.h"
#include <stddef.h>
#include <stdint.h>
#include <string>
#include <utility>
#include <vector>
#include "absl/types/optional.h"
#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/chunk/forward_tsn_common.h"
#include "net/dcsctp/packet/tlv_trait.h"
#include "rtc_base/strings/string_builder.h"
namespace dcsctp {
// https://tools.ietf.org/html/rfc3758#section-3.2
// 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 = 192 | Flags = 0x00 | Length = Variable |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | New Cumulative TSN |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Stream-1 | Stream Sequence-1 |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// \ /
// / \
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Stream-N | Stream Sequence-N |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
constexpr int ForwardTsnChunk::kType;
absl::optional<ForwardTsnChunk> ForwardTsnChunk::Parse(
rtc::ArrayView<const uint8_t> data) {
absl::optional<BoundedByteReader<kHeaderSize>> reader = ParseTLV(data);
if (!reader.has_value()) {
return absl::nullopt;
}
TSN new_cumulative_tsn(reader->Load32<4>());
size_t streams_skipped =
reader->variable_data_size() / kSkippedStreamBufferSize;
std::vector<SkippedStream> skipped_streams;
skipped_streams.reserve(streams_skipped);
for (size_t i = 0; i < streams_skipped; ++i) {
BoundedByteReader<kSkippedStreamBufferSize> sub_reader =
reader->sub_reader<kSkippedStreamBufferSize>(i *
kSkippedStreamBufferSize);
StreamID stream_id(sub_reader.Load16<0>());
SSN ssn(sub_reader.Load16<2>());
skipped_streams.emplace_back(stream_id, ssn);
}
return ForwardTsnChunk(new_cumulative_tsn, std::move(skipped_streams));
}
void ForwardTsnChunk::SerializeTo(std::vector<uint8_t>& out) const {
rtc::ArrayView<const SkippedStream> skipped = skipped_streams();
size_t variable_size = skipped.size() * kSkippedStreamBufferSize;
BoundedByteWriter<kHeaderSize> writer = AllocateTLV(out, variable_size);
writer.Store32<4>(*new_cumulative_tsn());
for (size_t i = 0; i < skipped.size(); ++i) {
BoundedByteWriter<kSkippedStreamBufferSize> sub_writer =
writer.sub_writer<kSkippedStreamBufferSize>(i *
kSkippedStreamBufferSize);
sub_writer.Store16<0>(*skipped[i].stream_id);
sub_writer.Store16<2>(*skipped[i].ssn);
}
}
std::string ForwardTsnChunk::ToString() const {
rtc::StringBuilder sb;
sb << "FORWARD-TSN, new_cumulative_tsn=" << *new_cumulative_tsn();
for (const auto& skipped : skipped_streams()) {
sb << ", skip " << skipped.stream_id.value() << ":" << *skipped.ssn;
}
return sb.str();
}
} // namespace dcsctp
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