webrtc/modules/rtp_rtcp/source/rtcp_packet.cc

/*
 *  Copyright (c) 2014 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 "webrtc/modules/rtp_rtcp/source/rtcp_packet.h"

#include "webrtc/base/checks.h"
#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
#include "webrtc/system_wrappers/interface/logging.h"

using webrtc::RTCPUtility::kBtDlrr;
using webrtc::RTCPUtility::kBtReceiverReferenceTime;
using webrtc::RTCPUtility::kBtVoipMetric;

using webrtc::RTCPUtility::PT_APP;
using webrtc::RTCPUtility::PT_BYE;
using webrtc::RTCPUtility::PT_IJ;
using webrtc::RTCPUtility::PT_PSFB;
using webrtc::RTCPUtility::PT_RR;
using webrtc::RTCPUtility::PT_RTPFB;
using webrtc::RTCPUtility::PT_SDES;
using webrtc::RTCPUtility::PT_SR;
using webrtc::RTCPUtility::PT_XR;

using webrtc::RTCPUtility::RTCPPacketAPP;
using webrtc::RTCPUtility::RTCPPacketBYE;
using webrtc::RTCPUtility::RTCPPacketPSFBAPP;
using webrtc::RTCPUtility::RTCPPacketPSFBFIR;
using webrtc::RTCPUtility::RTCPPacketPSFBFIRItem;
using webrtc::RTCPUtility::RTCPPacketPSFBPLI;
using webrtc::RTCPUtility::RTCPPacketPSFBREMBItem;
using webrtc::RTCPUtility::RTCPPacketPSFBRPSI;
using webrtc::RTCPUtility::RTCPPacketPSFBSLI;
using webrtc::RTCPUtility::RTCPPacketPSFBSLIItem;
using webrtc::RTCPUtility::RTCPPacketReportBlockItem;
using webrtc::RTCPUtility::RTCPPacketRR;
using webrtc::RTCPUtility::RTCPPacketRTPFBNACK;
using webrtc::RTCPUtility::RTCPPacketRTPFBNACKItem;
using webrtc::RTCPUtility::RTCPPacketRTPFBTMMBN;
using webrtc::RTCPUtility::RTCPPacketRTPFBTMMBNItem;
using webrtc::RTCPUtility::RTCPPacketRTPFBTMMBR;
using webrtc::RTCPUtility::RTCPPacketRTPFBTMMBRItem;
using webrtc::RTCPUtility::RTCPPacketSR;
using webrtc::RTCPUtility::RTCPPacketXRDLRRReportBlockItem;
using webrtc::RTCPUtility::RTCPPacketXRReceiverReferenceTimeItem;
using webrtc::RTCPUtility::RTCPPacketXR;
using webrtc::RTCPUtility::RTCPPacketXRVOIPMetricItem;

namespace webrtc {
namespace rtcp {
namespace {
// Unused SSRC of media source, set to 0.
const uint32_t kUnusedMediaSourceSsrc0 = 0;

void AssignUWord8(uint8_t* buffer, size_t* offset, uint8_t value) {
  buffer[(*offset)++] = value;
}
void AssignUWord16(uint8_t* buffer, size_t* offset, uint16_t value) {
  ByteWriter<uint16_t>::WriteBigEndian(buffer + *offset, value);
  *offset += 2;
}
void AssignUWord24(uint8_t* buffer, size_t* offset, uint32_t value) {
  ByteWriter<uint32_t, 3>::WriteBigEndian(buffer + *offset, value);
  *offset += 3;
}
void AssignUWord32(uint8_t* buffer, size_t* offset, uint32_t value) {
  ByteWriter<uint32_t>::WriteBigEndian(buffer + *offset, value);
  *offset += 4;
}

void ComputeMantissaAnd6bitBase2Exponent(uint32_t input_base10,
                                         uint8_t bits_mantissa,
                                         uint32_t* mantissa,
                                         uint8_t* exp) {
  // input_base10 = mantissa * 2^exp
  assert(bits_mantissa <= 32);
  uint32_t mantissa_max = (1 << bits_mantissa) - 1;
  uint8_t exponent = 0;
  for (uint32_t i = 0; i < 64; ++i) {
    if (input_base10 <= (mantissa_max << i)) {
      exponent = i;
      break;
    }
  }
  *exp = exponent;
  *mantissa = (input_base10 >> exponent);
}

size_t BlockToHeaderLength(size_t length_in_bytes) {
  // Length in 32-bit words minus 1.
  assert(length_in_bytes > 0);
  assert(length_in_bytes % 4 == 0);
  return (length_in_bytes / 4) - 1;
}

// From RFC 3550, RTP: A Transport Protocol for Real-Time Applications.
//
// RTP header format.
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |V=2|P| RC/FMT  |      PT       |             length            |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateHeader(uint8_t count_or_format,  // Depends on packet type.
                  uint8_t packet_type,
                  size_t length,
                  uint8_t* buffer,
                  size_t* pos) {
  assert(length <= 0xffff);
  const uint8_t kVersion = 2;
  AssignUWord8(buffer, pos, (kVersion << 6) + count_or_format);
  AssignUWord8(buffer, pos, packet_type);
  AssignUWord16(buffer, pos, length);
}

//  Sender report (SR) (RFC 3550).
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |V=2|P|    RC   |   PT=SR=200   |             length            |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                         SSRC of sender                        |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//  |              NTP timestamp, most significant word             |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |             NTP timestamp, least significant word             |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                         RTP timestamp                         |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                     sender's packet count                     |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                      sender's octet count                     |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+

void CreateSenderReport(const RTCPPacketSR& sr,
                        size_t length,
                        uint8_t* buffer,
                        size_t* pos) {
  CreateHeader(sr.NumberOfReportBlocks, PT_SR, length, buffer, pos);
  AssignUWord32(buffer, pos, sr.SenderSSRC);
  AssignUWord32(buffer, pos, sr.NTPMostSignificant);
  AssignUWord32(buffer, pos, sr.NTPLeastSignificant);
  AssignUWord32(buffer, pos, sr.RTPTimestamp);
  AssignUWord32(buffer, pos, sr.SenderPacketCount);
  AssignUWord32(buffer, pos, sr.SenderOctetCount);
}

//  Receiver report (RR), header (RFC 3550).
//
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |V=2|P|    RC   |   PT=RR=201   |             length            |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                     SSRC of packet sender                     |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+

void CreateReceiverReport(const RTCPPacketRR& rr,
                          size_t length,
                          uint8_t* buffer,
                          size_t* pos) {
  CreateHeader(rr.NumberOfReportBlocks, PT_RR, length, buffer, pos);
  AssignUWord32(buffer, pos, rr.SenderSSRC);
}

//  Report block (RFC 3550).
//
//   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
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//  |                 SSRC_1 (SSRC of first source)                 |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  | fraction lost |       cumulative number of packets lost       |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |           extended highest sequence number received           |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                      interarrival jitter                      |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                         last SR (LSR)                         |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                   delay since last SR (DLSR)                  |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+

void CreateReportBlocks(const std::vector<RTCPPacketReportBlockItem>& blocks,
                        uint8_t* buffer,
                        size_t* pos) {
  for (std::vector<RTCPPacketReportBlockItem>::const_iterator
       it = blocks.begin(); it != blocks.end(); ++it) {
    AssignUWord32(buffer, pos, (*it).SSRC);
    AssignUWord8(buffer, pos, (*it).FractionLost);
    AssignUWord24(buffer, pos, (*it).CumulativeNumOfPacketsLost);
    AssignUWord32(buffer, pos, (*it).ExtendedHighestSequenceNumber);
    AssignUWord32(buffer, pos, (*it).Jitter);
    AssignUWord32(buffer, pos, (*it).LastSR);
    AssignUWord32(buffer, pos, (*it).DelayLastSR);
  }
}

// Transmission Time Offsets in RTP Streams (RFC 5450).
//
//      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
//     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// hdr |V=2|P|    RC   |   PT=IJ=195   |             length            |
//     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//     |                      inter-arrival jitter                     |
//     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//     .                                                               .
//     .                                                               .
//     .                                                               .
//     |                      inter-arrival jitter                     |
//     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateIj(const std::vector<uint32_t>& ij_items,
              uint8_t* buffer,
              size_t* pos) {
  size_t length = ij_items.size();
  CreateHeader(length, PT_IJ, length, buffer, pos);
  for (std::vector<uint32_t>::const_iterator it = ij_items.begin();
       it != ij_items.end(); ++it) {
    AssignUWord32(buffer, pos, *it);
  }
}

// Source Description (SDES) (RFC 3550).
//
//         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
//        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// header |V=2|P|    SC   |  PT=SDES=202  |             length            |
//        +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
// chunk  |                          SSRC/CSRC_1                          |
//   1    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//        |                           SDES items                          |
//        |                              ...                              |
//        +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
// chunk  |                          SSRC/CSRC_2                          |
//   2    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//        |                           SDES items                          |
//        |                              ...                              |
//        +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//
// Canonical End-Point Identifier SDES Item (CNAME)
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |    CNAME=1    |     length    | user and domain name        ...
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateSdes(const std::vector<Sdes::Chunk>& chunks,
                size_t length,
                uint8_t* buffer,
                size_t* pos) {
  CreateHeader(chunks.size(), PT_SDES, length, buffer, pos);
  const uint8_t kSdesItemType = 1;
  for (std::vector<Sdes::Chunk>::const_iterator it = chunks.begin();
       it != chunks.end(); ++it) {
    AssignUWord32(buffer, pos, (*it).ssrc);
    AssignUWord8(buffer, pos, kSdesItemType);
    AssignUWord8(buffer, pos, (*it).name.length());
    memcpy(buffer + *pos, (*it).name.data(), (*it).name.length());
    *pos += (*it).name.length();
    memset(buffer + *pos, 0, (*it).null_octets);
    *pos += (*it).null_octets;
  }
}

// Bye packet (BYE) (RFC 3550).
//
//        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
//       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//       |V=2|P|    SC   |   PT=BYE=203  |             length            |
//       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//       |                           SSRC/CSRC                           |
//       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//       :                              ...                              :
//       +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
// (opt) |     length    |               reason for leaving            ...
//       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateBye(const RTCPPacketBYE& bye,
               const std::vector<uint32_t>& csrcs,
               size_t length,
               uint8_t* buffer,
               size_t* pos) {
  CreateHeader(length, PT_BYE, length, buffer, pos);
  AssignUWord32(buffer, pos, bye.SenderSSRC);
  for (uint32_t csrc : csrcs)
    AssignUWord32(buffer, pos, csrc);
}

// Application-Defined packet (APP) (RFC 3550).
//
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |V=2|P| subtype |   PT=APP=204  |             length            |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                           SSRC/CSRC                           |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                          name (ASCII)                         |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                   application-dependent data                ...
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateApp(const RTCPPacketAPP& app,
               uint32_t ssrc,
               size_t length,
               uint8_t* buffer,
               size_t* pos) {
  CreateHeader(app.SubType, PT_APP, length, buffer, pos);
  AssignUWord32(buffer, pos, ssrc);
  AssignUWord32(buffer, pos, app.Name);
  memcpy(buffer + *pos, app.Data, app.Size);
  *pos += app.Size;
}

// RFC 4585: Feedback format.
//
// Common packet format:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |V=2|P|   FMT   |       PT      |          length               |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                  SSRC of packet sender                        |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                  SSRC of media source                         |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   :            Feedback Control Information (FCI)                 :
//   :
//

// Picture loss indication (PLI) (RFC 4585).
//
// FCI: no feedback control information.

void CreatePli(const RTCPPacketPSFBPLI& pli,
               size_t length,
               uint8_t* buffer,
               size_t* pos) {
  const uint8_t kFmt = 1;
  CreateHeader(kFmt, PT_PSFB, length, buffer, pos);
  AssignUWord32(buffer, pos, pli.SenderSSRC);
  AssignUWord32(buffer, pos, pli.MediaSSRC);
}

// Slice loss indication (SLI) (RFC 4585).
//
// FCI:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |            First        |        Number           | PictureID |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateSli(const RTCPPacketPSFBSLI& sli,
               const RTCPPacketPSFBSLIItem& sli_item,
               size_t length,
               uint8_t* buffer,
               size_t* pos) {
  const uint8_t kFmt = 2;
  CreateHeader(kFmt, PT_PSFB, length, buffer, pos);
  AssignUWord32(buffer, pos, sli.SenderSSRC);
  AssignUWord32(buffer, pos, sli.MediaSSRC);

  AssignUWord8(buffer, pos, sli_item.FirstMB >> 5);
  AssignUWord8(buffer, pos, (sli_item.FirstMB << 3) +
                            ((sli_item.NumberOfMB >> 10) & 0x07));
  AssignUWord8(buffer, pos, sli_item.NumberOfMB >> 2);
  AssignUWord8(buffer, pos, (sli_item.NumberOfMB << 6) + sli_item.PictureId);
}

// Generic NACK (RFC 4585).
//
// FCI:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |            PID                |             BLP               |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateNack(const RTCPPacketRTPFBNACK& nack,
                const std::vector<RTCPPacketRTPFBNACKItem>& nack_fields,
                size_t start_index,
                size_t end_index,
                size_t length,
                uint8_t* buffer,
                size_t* pos) {
  const uint8_t kFmt = 1;
  CreateHeader(kFmt, PT_RTPFB, length, buffer, pos);
  AssignUWord32(buffer, pos, nack.SenderSSRC);
  AssignUWord32(buffer, pos, nack.MediaSSRC);
  for (size_t i = start_index; i < end_index; ++i) {
    const RTCPPacketRTPFBNACKItem& nack_item = nack_fields[i];
    AssignUWord16(buffer, pos, nack_item.PacketID);
    AssignUWord16(buffer, pos, nack_item.BitMask);
  }
}

// Reference picture selection indication (RPSI) (RFC 4585).
//
// FCI:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |      PB       |0| Payload Type|    Native RPSI bit string     |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |   defined per codec          ...                | Padding (0) |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateRpsi(const RTCPPacketPSFBRPSI& rpsi,
                uint8_t padding_bytes,
                size_t length,
                uint8_t* buffer,
                size_t* pos) {
  // Native bit string should be a multiple of 8 bits.
  assert(rpsi.NumberOfValidBits % 8 == 0);
  const uint8_t kFmt = 3;
  CreateHeader(kFmt, PT_PSFB, length, buffer, pos);
  AssignUWord32(buffer, pos, rpsi.SenderSSRC);
  AssignUWord32(buffer, pos, rpsi.MediaSSRC);
  AssignUWord8(buffer, pos, padding_bytes * 8);
  AssignUWord8(buffer, pos, rpsi.PayloadType);
  memcpy(buffer + *pos, rpsi.NativeBitString, rpsi.NumberOfValidBits / 8);
  *pos += rpsi.NumberOfValidBits / 8;
  memset(buffer + *pos, 0, padding_bytes);
  *pos += padding_bytes;
}

// Full intra request (FIR) (RFC 5104).
//
// FCI:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                              SSRC                             |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   | Seq nr.       |    Reserved                                   |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateFir(const RTCPPacketPSFBFIR& fir,
               const RTCPPacketPSFBFIRItem& fir_item,
               size_t length,
               uint8_t* buffer,
               size_t* pos) {
  const uint8_t kFmt = 4;
  CreateHeader(kFmt, PT_PSFB, length, buffer, pos);
  AssignUWord32(buffer, pos, fir.SenderSSRC);
  AssignUWord32(buffer, pos, kUnusedMediaSourceSsrc0);
  AssignUWord32(buffer, pos, fir_item.SSRC);
  AssignUWord8(buffer, pos, fir_item.CommandSequenceNumber);
  AssignUWord24(buffer, pos, 0);
}

void CreateTmmbrItem(const RTCPPacketRTPFBTMMBRItem& tmmbr_item,
                     uint8_t* buffer,
                     size_t* pos) {
  uint32_t bitrate_bps = tmmbr_item.MaxTotalMediaBitRate * 1000;
  uint32_t mantissa = 0;
  uint8_t exp = 0;
  ComputeMantissaAnd6bitBase2Exponent(bitrate_bps, 17, &mantissa, &exp);

  AssignUWord32(buffer, pos, tmmbr_item.SSRC);
  AssignUWord8(buffer, pos, (exp << 2) + ((mantissa >> 15) & 0x03));
  AssignUWord8(buffer, pos, mantissa >> 7);
  AssignUWord8(buffer, pos, (mantissa << 1) +
                            ((tmmbr_item.MeasuredOverhead >> 8) & 0x01));
  AssignUWord8(buffer, pos, tmmbr_item.MeasuredOverhead);
}

// Temporary Maximum Media Stream Bit Rate Request (TMMBR) (RFC 5104).
//
// FCI:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                              SSRC                             |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   | MxTBR Exp |  MxTBR Mantissa                 |Measured Overhead|
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateTmmbr(const RTCPPacketRTPFBTMMBR& tmmbr,
                 const RTCPPacketRTPFBTMMBRItem& tmmbr_item,
                 size_t length,
                 uint8_t* buffer,
                 size_t* pos) {
  const uint8_t kFmt = 3;
  CreateHeader(kFmt, PT_RTPFB, length, buffer, pos);
  AssignUWord32(buffer, pos, tmmbr.SenderSSRC);
  AssignUWord32(buffer, pos, kUnusedMediaSourceSsrc0);
  CreateTmmbrItem(tmmbr_item, buffer, pos);
}

// Temporary Maximum Media Stream Bit Rate Notification (TMMBN) (RFC 5104).
//
// FCI:
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                              SSRC                             |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   | MxTBR Exp |  MxTBR Mantissa                 |Measured Overhead|
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateTmmbn(const RTCPPacketRTPFBTMMBN& tmmbn,
                 const std::vector<RTCPPacketRTPFBTMMBRItem>& tmmbn_items,
                 size_t length,
                 uint8_t* buffer,
                 size_t* pos) {
  const uint8_t kFmt = 4;
  CreateHeader(kFmt, PT_RTPFB, length, buffer, pos);
  AssignUWord32(buffer, pos, tmmbn.SenderSSRC);
  AssignUWord32(buffer, pos, kUnusedMediaSourceSsrc0);
  for (uint8_t i = 0; i < tmmbn_items.size(); ++i) {
    CreateTmmbrItem(tmmbn_items[i], buffer, pos);
  }
}

// Receiver Estimated Max Bitrate (REMB) (draft-alvestrand-rmcat-remb).
//
//    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
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |V=2|P| FMT=15  |   PT=206      |             length            |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                  SSRC of packet sender                        |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |                  SSRC of media source                         |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |  Unique identifier 'R' 'E' 'M' 'B'                            |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |  Num SSRC     | BR Exp    |  BR Mantissa                      |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |   SSRC feedback                                               |
//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//   |  ...                                                          |

void CreateRemb(const RTCPPacketPSFBAPP& remb,
                const RTCPPacketPSFBREMBItem& remb_item,
                size_t length,
                uint8_t* buffer,
                size_t* pos) {
  uint32_t mantissa = 0;
  uint8_t exp = 0;
  ComputeMantissaAnd6bitBase2Exponent(remb_item.BitRate, 18, &mantissa, &exp);

  const uint8_t kFmt = 15;
  CreateHeader(kFmt, PT_PSFB, length, buffer, pos);
  AssignUWord32(buffer, pos, remb.SenderSSRC);
  AssignUWord32(buffer, pos, kUnusedMediaSourceSsrc0);
  AssignUWord8(buffer, pos, 'R');
  AssignUWord8(buffer, pos, 'E');
  AssignUWord8(buffer, pos, 'M');
  AssignUWord8(buffer, pos, 'B');
  AssignUWord8(buffer, pos, remb_item.NumberOfSSRCs);
  AssignUWord8(buffer, pos, (exp << 2) + ((mantissa >> 16) & 0x03));
  AssignUWord8(buffer, pos, mantissa >> 8);
  AssignUWord8(buffer, pos, mantissa);
  for (uint8_t i = 0; i < remb_item.NumberOfSSRCs; ++i) {
    AssignUWord32(buffer, pos, remb_item.SSRCs[i]);
  }
}

// From RFC 3611: RTP Control Protocol Extended Reports (RTCP XR).
//
// Format for XR packets:
//
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |V=2|P|reserved |   PT=XR=207   |             length            |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                              SSRC                             |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  :                         report blocks                         :
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateXrHeader(const RTCPPacketXR& header,
                    size_t length,
                    uint8_t* buffer,
                    size_t* pos) {
  CreateHeader(0U, PT_XR, length, buffer, pos);
  AssignUWord32(buffer, pos, header.OriginatorSSRC);
}

void CreateXrBlockHeader(uint8_t block_type,
                         uint16_t block_length,
                         uint8_t* buffer,
                         size_t* pos) {
  AssignUWord8(buffer, pos, block_type);
  AssignUWord8(buffer, pos, 0);
  AssignUWord16(buffer, pos, block_length);
}

// Receiver Reference Time Report Block (RFC 3611).
//
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |     BT=4      |   reserved    |       block length = 2        |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |              NTP timestamp, most significant word             |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |             NTP timestamp, least significant word             |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateRrtr(const std::vector<RTCPPacketXRReceiverReferenceTimeItem>& rrtrs,
                uint8_t* buffer,
                size_t* pos) {
  const uint16_t kBlockLength = 2;
  for (std::vector<RTCPPacketXRReceiverReferenceTimeItem>::const_iterator it =
       rrtrs.begin(); it != rrtrs.end(); ++it) {
    CreateXrBlockHeader(kBtReceiverReferenceTime, kBlockLength, buffer, pos);
    AssignUWord32(buffer, pos, (*it).NTPMostSignificant);
    AssignUWord32(buffer, pos, (*it).NTPLeastSignificant);
  }
}

// DLRR Report Block (RFC 3611).
//
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |     BT=5      |   reserved    |         block length          |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//  |                 SSRC_1 (SSRC of first receiver)               | sub-
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block
//  |                         last RR (LRR)                         |   1
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                   delay since last RR (DLRR)                  |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//  |                 SSRC_2 (SSRC of second receiver)              | sub-
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block
//  :                               ...                             :   2

void CreateDlrr(const std::vector<Xr::DlrrBlock>& dlrrs,
                uint8_t* buffer,
                size_t* pos) {
  for (std::vector<Xr::DlrrBlock>::const_iterator it = dlrrs.begin();
       it != dlrrs.end(); ++it) {
    if ((*it).empty()) {
      continue;
    }
    uint16_t block_length = 3 * (*it).size();
    CreateXrBlockHeader(kBtDlrr, block_length, buffer, pos);
    for (Xr::DlrrBlock::const_iterator it_block = (*it).begin();
         it_block != (*it).end(); ++it_block) {
      AssignUWord32(buffer, pos, (*it_block).SSRC);
      AssignUWord32(buffer, pos, (*it_block).LastRR);
      AssignUWord32(buffer, pos, (*it_block).DelayLastRR);
    }
  }
}

// VoIP Metrics Report Block (RFC 3611).
//
//   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
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |     BT=7      |   reserved    |       block length = 8        |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |                        SSRC of source                         |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |   loss rate   | discard rate  | burst density |  gap density  |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |       burst duration          |         gap duration          |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |     round trip delay          |       end system delay        |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  | signal level  |  noise level  |     RERL      |     Gmin      |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |   R factor    | ext. R factor |    MOS-LQ     |    MOS-CQ     |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |   RX config   |   reserved    |          JB nominal           |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |          JB maximum           |          JB abs max           |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

void CreateVoipMetric(const std::vector<RTCPPacketXRVOIPMetricItem>& metrics,
                      uint8_t* buffer,
                      size_t* pos) {
  const uint16_t kBlockLength = 8;
  for (std::vector<RTCPPacketXRVOIPMetricItem>::const_iterator it =
       metrics.begin(); it != metrics.end(); ++it) {
    CreateXrBlockHeader(kBtVoipMetric, kBlockLength, buffer, pos);
    AssignUWord32(buffer, pos, (*it).SSRC);
    AssignUWord8(buffer, pos, (*it).lossRate);
    AssignUWord8(buffer, pos, (*it).discardRate);
    AssignUWord8(buffer, pos, (*it).burstDensity);
    AssignUWord8(buffer, pos, (*it).gapDensity);
    AssignUWord16(buffer, pos, (*it).burstDuration);
    AssignUWord16(buffer, pos, (*it).gapDuration);
    AssignUWord16(buffer, pos, (*it).roundTripDelay);
    AssignUWord16(buffer, pos, (*it).endSystemDelay);
    AssignUWord8(buffer, pos, (*it).signalLevel);
    AssignUWord8(buffer, pos, (*it).noiseLevel);
    AssignUWord8(buffer, pos, (*it).RERL);
    AssignUWord8(buffer, pos, (*it).Gmin);
    AssignUWord8(buffer, pos, (*it).Rfactor);
    AssignUWord8(buffer, pos, (*it).extRfactor);
    AssignUWord8(buffer, pos, (*it).MOSLQ);
    AssignUWord8(buffer, pos, (*it).MOSCQ);
    AssignUWord8(buffer, pos, (*it).RXconfig);
    AssignUWord8(buffer, pos, 0);
    AssignUWord16(buffer, pos, (*it).JBnominal);
    AssignUWord16(buffer, pos, (*it).JBmax);
    AssignUWord16(buffer, pos, (*it).JBabsMax);
  }
}
}  // namespace

void RtcpPacket::Append(RtcpPacket* packet) {
  assert(packet);
  appended_packets_.push_back(packet);
}

rtc::scoped_ptr<RawPacket> RtcpPacket::Build() const {
  size_t length = 0;
  rtc::scoped_ptr<RawPacket> packet(new RawPacket(IP_PACKET_SIZE));

  class PacketVerifier : public PacketReadyCallback {
   public:
    explicit PacketVerifier(RawPacket* packet)
        : called_(false), packet_(packet) {}
    virtual ~PacketVerifier() {}
    void OnPacketReady(uint8_t* data, size_t length) override {
      CHECK(!called_) << "Fragmentation not supported.";
      called_ = true;
      packet_->SetLength(length);
    }

   private:
    bool called_;
    RawPacket* const packet_;
  } verifier(packet.get());
  CreateAndAddAppended(packet->MutableBuffer(), &length, packet->BufferLength(),
                       &verifier);
  OnBufferFull(packet->MutableBuffer(), &length, &verifier);
  return packet;
}

bool RtcpPacket::Build(PacketReadyCallback* callback) const {
  uint8_t buffer[IP_PACKET_SIZE];
  return BuildExternalBuffer(buffer, IP_PACKET_SIZE, callback);
}

bool RtcpPacket::BuildExternalBuffer(uint8_t* buffer,
                                     size_t max_length,
                                     PacketReadyCallback* callback) const {
  size_t index = 0;
  if (!CreateAndAddAppended(buffer, &index, max_length, callback))
    return false;
  return OnBufferFull(buffer, &index, callback);
}

bool RtcpPacket::CreateAndAddAppended(uint8_t* packet,
                                      size_t* index,
                                      size_t max_length,
                                      PacketReadyCallback* callback) const {
  if (!Create(packet, index, max_length, callback))
    return false;
  for (RtcpPacket* appended : appended_packets_) {
    if (!appended->CreateAndAddAppended(packet, index, max_length, callback))
      return false;
  }
  return true;
}

bool RtcpPacket::OnBufferFull(uint8_t* packet,
                              size_t* index,
                              RtcpPacket::PacketReadyCallback* callback) const {
  if (*index == 0)
    return false;
  callback->OnPacketReady(packet, *index);
  *index = 0;
  return true;
}

bool Empty::Create(uint8_t* packet,
                   size_t* index,
                   size_t max_length,
                   RtcpPacket::PacketReadyCallback* callback) const {
  return true;
}

bool SenderReport::Create(uint8_t* packet,
                          size_t* index,
                          size_t max_length,
                          RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateSenderReport(sr_, BlockToHeaderLength(BlockLength()), packet, index);
  CreateReportBlocks(report_blocks_, packet, index);
  return true;
}

bool SenderReport::WithReportBlock(ReportBlock* block) {
  assert(block);
  if (report_blocks_.size() >= kMaxNumberOfReportBlocks) {
    LOG(LS_WARNING) << "Max report blocks reached.";
    return false;
  }
  report_blocks_.push_back(block->report_block_);
  sr_.NumberOfReportBlocks = report_blocks_.size();
  return true;
}

bool ReceiverReport::Create(uint8_t* packet,
                            size_t* index,
                            size_t max_length,
                            RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateReceiverReport(rr_, BlockToHeaderLength(BlockLength()), packet, index);
  CreateReportBlocks(report_blocks_, packet, index);
  return true;
}

bool ReceiverReport::WithReportBlock(ReportBlock* block) {
  assert(block);
  if (report_blocks_.size() >= kMaxNumberOfReportBlocks) {
    LOG(LS_WARNING) << "Max report blocks reached.";
    return false;
  }
  report_blocks_.push_back(block->report_block_);
  rr_.NumberOfReportBlocks = report_blocks_.size();
  return true;
}

bool Ij::Create(uint8_t* packet,
                size_t* index,
                size_t max_length,
                RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateIj(ij_items_, packet, index);
  return true;
}

bool Ij::WithJitterItem(uint32_t jitter) {
  if (ij_items_.size() >= kMaxNumberOfIjItems) {
    LOG(LS_WARNING) << "Max inter-arrival jitter items reached.";
    return false;
  }
  ij_items_.push_back(jitter);
  return true;
}

bool Sdes::Create(uint8_t* packet,
                  size_t* index,
                  size_t max_length,
                  RtcpPacket::PacketReadyCallback* callback) const {
  assert(!chunks_.empty());
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateSdes(chunks_, BlockToHeaderLength(BlockLength()), packet, index);
  return true;
}

bool Sdes::WithCName(uint32_t ssrc, const std::string& cname) {
  assert(cname.length() <= 0xff);
  if (chunks_.size() >= kMaxNumberOfChunks) {
    LOG(LS_WARNING) << "Max SDES chunks reached.";
    return false;
  }
  // In each chunk, the list of items must be terminated by one or more null
  // octets. The next chunk must start on a 32-bit boundary.
  // CNAME (1 byte) | length (1 byte) | name | padding.
  int null_octets = 4 - ((2 + cname.length()) % 4);
  Chunk chunk;
  chunk.ssrc = ssrc;
  chunk.name = cname;
  chunk.null_octets = null_octets;
  chunks_.push_back(chunk);
  return true;
}

size_t Sdes::BlockLength() const {
  // Header (4 bytes).
  // Chunk:
  // SSRC/CSRC (4 bytes) | CNAME (1 byte) | length (1 byte) | name | padding.
  size_t length = kHeaderLength;
  for (const Chunk& chunk : chunks_)
    length += 6 + chunk.name.length() + chunk.null_octets;
  assert(length % 4 == 0);
  return length;
}

bool Bye::Create(uint8_t* packet,
                 size_t* index,
                 size_t max_length,
                 RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateBye(bye_, csrcs_, BlockToHeaderLength(BlockLength()), packet, index);
  return true;
}

bool Bye::WithCsrc(uint32_t csrc) {
  if (csrcs_.size() >= kMaxNumberOfCsrcs) {
    LOG(LS_WARNING) << "Max CSRC size reached.";
    return false;
  }
  csrcs_.push_back(csrc);
  return true;
}

bool App::Create(uint8_t* packet,
                 size_t* index,
                 size_t max_length,
                 RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateApp(app_, ssrc_, BlockToHeaderLength(BlockLength()), packet, index);
  return true;
}

bool Pli::Create(uint8_t* packet,
                 size_t* index,
                 size_t max_length,
                 RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreatePli(pli_, BlockToHeaderLength(BlockLength()), packet, index);
  return true;
}

bool Sli::Create(uint8_t* packet,
                 size_t* index,
                 size_t max_length,
                 RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateSli(sli_, sli_item_, BlockToHeaderLength(BlockLength()), packet, index);
  return true;
}

bool Nack::Create(uint8_t* packet,
                  size_t* index,
                  size_t max_length,
                  RtcpPacket::PacketReadyCallback* callback) const {
  assert(!nack_fields_.empty());
  // If nack list can't fit in packet, try to fragment.
  size_t nack_index = 0;
  do {
    size_t bytes_left_in_buffer = max_length - *index;
    if (bytes_left_in_buffer < kCommonFbFmtLength + 4) {
      if (!OnBufferFull(packet, index, callback))
        return false;
      continue;
    }
    int64_t num_nack_fields =
        std::min((bytes_left_in_buffer - kCommonFbFmtLength) / 4,
                 nack_fields_.size() - nack_index);

    CreateNack(nack_, nack_fields_, nack_index, nack_index + num_nack_fields,
               BlockToHeaderLength((num_nack_fields * 4) + kCommonFbFmtLength),
               packet, index);

    nack_index += num_nack_fields;
  } while (nack_index < nack_fields_.size());

  return true;
}

void Nack::WithList(const uint16_t* nack_list, int length) {
  assert(nack_list);
  assert(nack_fields_.empty());
  int i = 0;
  while (i < length) {
    uint16_t pid = nack_list[i++];
    // Bitmask specifies losses in any of the 16 packets following the pid.
    uint16_t bitmask = 0;
    while (i < length) {
      int shift = static_cast<uint16_t>(nack_list[i] - pid) - 1;
      if (shift >= 0 && shift <= 15) {
        bitmask |= (1 << shift);
        ++i;
      } else {
        break;
      }
    }
    RTCPUtility::RTCPPacketRTPFBNACKItem item;
    item.PacketID = pid;
    item.BitMask = bitmask;
    nack_fields_.push_back(item);
  }
}

bool Rpsi::Create(uint8_t* packet,
                  size_t* index,
                  size_t max_length,
                  RtcpPacket::PacketReadyCallback* callback) const {
  assert(rpsi_.NumberOfValidBits > 0);
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateRpsi(rpsi_, padding_bytes_, BlockToHeaderLength(BlockLength()), packet,
             index);
  return true;
}

void Rpsi::WithPictureId(uint64_t picture_id) {
  const uint32_t kPidBits = 7;
  const uint64_t k7MsbZeroMask = 0x1ffffffffffffffULL;
  uint8_t required_bytes = 0;
  uint64_t shifted_pid = picture_id;
  do {
    ++required_bytes;
    shifted_pid = (shifted_pid >> kPidBits) & k7MsbZeroMask;
  } while (shifted_pid > 0);

  // Convert picture id to native bit string (natively defined by the video
  // codec).
  int pos = 0;
  for (int i = required_bytes - 1; i > 0; i--) {
    rpsi_.NativeBitString[pos++] =
        0x80 | static_cast<uint8_t>(picture_id >> (i * kPidBits));
  }
  rpsi_.NativeBitString[pos++] = static_cast<uint8_t>(picture_id & 0x7f);
  rpsi_.NumberOfValidBits = pos * 8;

  // Calculate padding bytes (to reach next 32-bit boundary, 1, 2 or 3 bytes).
  padding_bytes_ = 4 - ((2 + required_bytes) % 4);
  if (padding_bytes_ == 4) {
    padding_bytes_ = 0;
  }
}

bool Fir::Create(uint8_t* packet,
                 size_t* index,
                 size_t max_length,
                 RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateFir(fir_, fir_item_, BlockToHeaderLength(BlockLength()), packet, index);
  return true;
}

bool Remb::Create(uint8_t* packet,
                  size_t* index,
                  size_t max_length,
                  RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateRemb(remb_, remb_item_, BlockToHeaderLength(BlockLength()), packet,
             index);
  return true;
}

void Remb::AppliesTo(uint32_t ssrc) {
  if (remb_item_.NumberOfSSRCs >= kMaxNumberOfSsrcs) {
    LOG(LS_WARNING) << "Max number of REMB feedback SSRCs reached.";
    return;
  }
  remb_item_.SSRCs[remb_item_.NumberOfSSRCs++] = ssrc;
}

bool Tmmbr::Create(uint8_t* packet,
                   size_t* index,
                   size_t max_length,
                   RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateTmmbr(tmmbr_, tmmbr_item_, BlockToHeaderLength(BlockLength()), packet,
              index);
  return true;
}

bool Tmmbn::WithTmmbr(uint32_t ssrc, uint32_t bitrate_kbps, uint16_t overhead) {
  assert(overhead <= 0x1ff);
  if (tmmbn_items_.size() >= kMaxNumberOfTmmbrs) {
    LOG(LS_WARNING) << "Max TMMBN size reached.";
    return false;
  }
  RTCPPacketRTPFBTMMBRItem tmmbn_item;
  tmmbn_item.SSRC = ssrc;
  tmmbn_item.MaxTotalMediaBitRate = bitrate_kbps;
  tmmbn_item.MeasuredOverhead = overhead;
  tmmbn_items_.push_back(tmmbn_item);
  return true;
}

bool Tmmbn::Create(uint8_t* packet,
                   size_t* index,
                   size_t max_length,
                   RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateTmmbn(tmmbn_, tmmbn_items_, BlockToHeaderLength(BlockLength()), packet,
              index);
  return true;
}

bool Xr::Create(uint8_t* packet,
                size_t* index,
                size_t max_length,
                RtcpPacket::PacketReadyCallback* callback) const {
  while (*index + BlockLength() > max_length) {
    if (!OnBufferFull(packet, index, callback))
      return false;
  }
  CreateXrHeader(xr_header_, BlockToHeaderLength(BlockLength()), packet, index);
  CreateRrtr(rrtr_blocks_, packet, index);
  CreateDlrr(dlrr_blocks_, packet, index);
  CreateVoipMetric(voip_metric_blocks_, packet, index);
  return true;
}

bool Xr::WithRrtr(Rrtr* rrtr) {
  assert(rrtr);
  if (rrtr_blocks_.size() >= kMaxNumberOfRrtrBlocks) {
    LOG(LS_WARNING) << "Max RRTR blocks reached.";
    return false;
  }
  rrtr_blocks_.push_back(rrtr->rrtr_block_);
  return true;
}

bool Xr::WithDlrr(Dlrr* dlrr) {
  assert(dlrr);
  if (dlrr_blocks_.size() >= kMaxNumberOfDlrrBlocks) {
    LOG(LS_WARNING) << "Max DLRR blocks reached.";
    return false;
  }
  dlrr_blocks_.push_back(dlrr->dlrr_block_);
  return true;
}

bool Xr::WithVoipMetric(VoipMetric* voip_metric) {
  assert(voip_metric);
  if (voip_metric_blocks_.size() >= kMaxNumberOfVoipMetricBlocks) {
    LOG(LS_WARNING) << "Max Voip Metric blocks reached.";
    return false;
  }
  voip_metric_blocks_.push_back(voip_metric->metric_);
  return true;
}

size_t Xr::DlrrLength() const {
  const size_t kBlockHeaderLen = 4;
  const size_t kSubBlockLen = 12;
  size_t length = 0;
  for (std::vector<DlrrBlock>::const_iterator it = dlrr_blocks_.begin();
       it != dlrr_blocks_.end(); ++it) {
    if (!(*it).empty()) {
      length += kBlockHeaderLen + kSubBlockLen * (*it).size();
    }
  }
  return length;
}

bool Dlrr::WithDlrrItem(uint32_t ssrc,
                        uint32_t last_rr,
                        uint32_t delay_last_rr) {
  if (dlrr_block_.size() >= kMaxNumberOfDlrrItems) {
    LOG(LS_WARNING) << "Max DLRR items reached.";
    return false;
  }
  RTCPPacketXRDLRRReportBlockItem dlrr;
  dlrr.SSRC = ssrc;
  dlrr.LastRR = last_rr;
  dlrr.DelayLastRR = delay_last_rr;
  dlrr_block_.push_back(dlrr);
  return true;
}

RawPacket::RawPacket(size_t buffer_length)
    : buffer_length_(buffer_length), length_(0) {
  buffer_.reset(new uint8_t[buffer_length]);
}

RawPacket::RawPacket(const uint8_t* packet, size_t packet_length)
    : buffer_length_(packet_length), length_(packet_length) {
  buffer_.reset(new uint8_t[packet_length]);
  memcpy(buffer_.get(), packet, packet_length);
}

const uint8_t* RawPacket::Buffer() const {
  return buffer_.get();
}

uint8_t* RawPacket::MutableBuffer() {
  return buffer_.get();
}

size_t RawPacket::BufferLength() const {
  return buffer_length_;
}

size_t RawPacket::Length() const {
  return length_;
}

void RawPacket::SetLength(size_t length) {
  assert(length <= buffer_length_);
  length_ = length;
}

}  // namespace rtcp
}  // namespace webrtc