state_cookie.cc - mozsearch

/*

 *  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/socket/state_cookie.h"

#include <cstdint>

#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/socket/capabilities.h"

#include "rtc_base/logging.h"

namespace dcsctp {

// Magic values, which the state cookie is prefixed with.

constexpr uint32_t kMagic1 = 1684230979;

constexpr uint32_t kMagic2 = 1414541360;

constexpr size_t StateCookie::kCookieSize;

std::vector<uint8_t> StateCookie::Serialize() {

  std::vector<uint8_t> cookie;

  cookie.resize(kCookieSize);

  BoundedByteWriter<kCookieSize> buffer(cookie);

  buffer.Store32<0>(kMagic1);

  buffer.Store32<4>(kMagic2);

  buffer.Store32<8>(*peer_tag_);

  buffer.Store32<12>(*my_tag_);

  buffer.Store32<16>(*peer_initial_tsn_);

  buffer.Store32<20>(*my_initial_tsn_);

  buffer.Store32<24>(a_rwnd_);

  buffer.Store32<28>(static_cast<uint32_t>(*tie_tag_ >> 32));

  buffer.Store32<32>(static_cast<uint32_t>(*tie_tag_));

  buffer.Store8<36>(capabilities_.partial_reliability);

  buffer.Store8<37>(capabilities_.message_interleaving);

  buffer.Store8<38>(capabilities_.reconfig);

  buffer.Store8<39>(capabilities_.zero_checksum);

  buffer.Store16<40>(capabilities_.negotiated_maximum_incoming_streams);

  buffer.Store16<42>(capabilities_.negotiated_maximum_outgoing_streams);

  return cookie;

absl::optional<StateCookie> StateCookie::Deserialize(

    rtc::ArrayView<const uint8_t> cookie) {

  if (cookie.size() != kCookieSize) {

    RTC_DLOG(LS_WARNING) << "Invalid state cookie: " << cookie.size()

                         << " bytes";

    return absl::nullopt;

  BoundedByteReader<kCookieSize> buffer(cookie);

  uint32_t magic1 = buffer.Load32<0>();

  uint32_t magic2 = buffer.Load32<4>();

  if (magic1 != kMagic1 || magic2 != kMagic2) {

    RTC_DLOG(LS_WARNING) << "Invalid state cookie; wrong magic";

    return absl::nullopt;

  VerificationTag peer_tag(buffer.Load32<8>());

  VerificationTag my_tag(buffer.Load32<12>());

  TSN peer_initial_tsn(buffer.Load32<16>());

  TSN my_initial_tsn(buffer.Load32<20>());

  uint32_t a_rwnd = buffer.Load32<24>();

  uint32_t tie_tag_upper = buffer.Load32<28>();

  uint32_t tie_tag_lower = buffer.Load32<32>();

  TieTag tie_tag(static_cast<uint64_t>(tie_tag_upper) << 32 |

                 static_cast<uint64_t>(tie_tag_lower));

  Capabilities capabilities;

  capabilities.partial_reliability = buffer.Load8<36>() != 0;

  capabilities.message_interleaving = buffer.Load8<37>() != 0;

  capabilities.reconfig = buffer.Load8<38>() != 0;

  capabilities.zero_checksum = buffer.Load8<39>() != 0;

  capabilities.negotiated_maximum_incoming_streams = buffer.Load16<40>();

  capabilities.negotiated_maximum_outgoing_streams = buffer.Load16<42>();

  return StateCookie(peer_tag, my_tag, peer_initial_tsn, my_initial_tsn, a_rwnd,

                     tie_tag, capabilities);

}  // namespace dcsctp