net/dcsctp/packet/error_cause/no_user_data_cause.cc

/*
 *  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/error_cause/no_user_data_cause.h"

#include <cstdint>
#include <optional>
#include <span>
#include <string>
#include <vector>

#include "net/dcsctp/common/internal_types.h"
#include "net/dcsctp/packet/bounded_byte_reader.h"
#include "net/dcsctp/packet/bounded_byte_writer.h"
#include "rtc_base/strings/string_builder.h"

namespace dcsctp {

// https://tools.ietf.org/html/rfc4960#section-3.3.10.9

//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |     Cause Code=9              |      Cause Length=8           |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  /                  TSN value                                    /
//  \                                                               \
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

std::optional<NoUserDataCause> NoUserDataCause::Parse(
    std::span<const uint8_t> data) {
  std::optional<BoundedByteReader<kHeaderSize>> reader = ParseTLV(data);
  if (!reader.has_value()) {
    return std::nullopt;
  }
  TSN tsn(reader->Load32<4>());
  return NoUserDataCause(tsn);
}

void NoUserDataCause::SerializeTo(std::vector<uint8_t>& out) const {
  BoundedByteWriter<kHeaderSize> writer = AllocateTLV(out);
  writer.Store32<4>(*tsn_);
}

std::string NoUserDataCause::ToString() const {
  webrtc::StringBuilder sb;
  sb << "No User Data, tsn=" << *tsn_;
  return sb.Release();
}
}  // namespace dcsctp