/*
 *  Copyright (c) 2017 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 <algorithm>

#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "modules/rtp_rtcp/include/ulpfec_receiver.h"
#include "modules/rtp_rtcp/source/byte_io.h"
#include "modules/rtp_rtcp/source/rtp_packet_received.h"

namespace webrtc {

namespace {
class DummyCallback : public RecoveredPacketReceiver {
  void OnRecoveredPacket(const uint8_t* packet, size_t length) override {}
};
}  // namespace

void FuzzOneInput(const uint8_t* data, size_t size) {
  constexpr size_t kMinDataNeeded = 12;
  if (size < kMinDataNeeded || size > 2000) {
    return;
  }

  uint32_t ulpfec_ssrc = ByteReader<uint32_t>::ReadLittleEndian(data + 0);
  uint16_t ulpfec_seq_num = ByteReader<uint16_t>::ReadLittleEndian(data + 4);
  uint32_t media_ssrc = ByteReader<uint32_t>::ReadLittleEndian(data + 6);
  uint16_t media_seq_num = ByteReader<uint16_t>::ReadLittleEndian(data + 10);

  DummyCallback callback;
  std::unique_ptr<UlpfecReceiver> receiver(
      UlpfecReceiver::Create(ulpfec_ssrc, &callback, {}));

  std::unique_ptr<uint8_t[]> packet;
  size_t packet_length;
  size_t i = kMinDataNeeded;
  while (i < size) {
    packet_length = kRtpHeaderSize + data[i++];
    packet = std::unique_ptr<uint8_t[]>(new uint8_t[packet_length]);
    if (i + packet_length >= size) {
      break;
    }
    memcpy(packet.get(), data + i, packet_length);
    i += packet_length;
    // Overwrite the RTPHeader fields for the sequence number and SSRC with
    // consistent values for either a received UlpFEC packet or received media
    // packet. (We're still relying on libfuzzer to manage to generate packet
    // headers that interact together; this just ensures that we have two
    // consistent streams).
    if (i < size && data[i++] % 2 == 0) {
      // Simulate UlpFEC packet.
      ByteWriter<uint16_t>::WriteBigEndian(packet.get() + 2, ulpfec_seq_num++);
      ByteWriter<uint32_t>::WriteBigEndian(packet.get() + 8, ulpfec_ssrc);
    } else {
      // Simulate media packet.
      ByteWriter<uint16_t>::WriteBigEndian(packet.get() + 2, media_seq_num++);
      ByteWriter<uint32_t>::WriteBigEndian(packet.get() + 8, media_ssrc);
    }
    RtpPacketReceived parsed_packet;
    RTPHeader parsed_header;
    if (parsed_packet.Parse(packet.get(), packet_length)) {
      parsed_packet.GetHeader(&parsed_header);
      receiver->AddReceivedRedPacket(parsed_header, packet.get(), packet_length,
                                     0);
    }
  }

  receiver->ProcessReceivedFec();
}

}  // namespace webrtc