tor-browser

The Tor Browser
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tmmbn.cc (4303B)

      1 /*
      2 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
      3 *
      4 *  Use of this source code is governed by a BSD-style license
      5 *  that can be found in the LICENSE file in the root of the source
      6 *  tree. An additional intellectual property rights grant can be found
      7 *  in the file PATENTS.  All contributing project authors may
      8 *  be found in the AUTHORS file in the root of the source tree.
      9 */
     10 
     11 #include "modules/rtp_rtcp/source/rtcp_packet/tmmbn.h"
     12 
     13 #include <cstddef>
     14 #include <cstdint>
     15 
     16 #include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
     17 #include "modules/rtp_rtcp/source/rtcp_packet/rtpfb.h"
     18 #include "modules/rtp_rtcp/source/rtcp_packet/tmmb_item.h"
     19 #include "rtc_base/checks.h"
     20 #include "rtc_base/logging.h"
     21 
     22 namespace webrtc {
     23 namespace rtcp {
     24 // RFC 4585: Feedback format.
     25 // Common packet format:
     26 //
     27 //    0                   1                   2                   3
     28 //    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
     29 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     30 //   |V=2|P|   FMT   |       PT      |          length               |
     31 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     32 //   |                  SSRC of packet sender                        |
     33 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     34 //   |             SSRC of media source (unused) = 0                 |
     35 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     36 //   :            Feedback Control Information (FCI)                 :
     37 //   :                                                               :
     38 // Temporary Maximum Media Stream Bit Rate Notification (TMMBN) (RFC 5104).
     39 // The Feedback Control Information (FCI) consists of zero, one, or more
     40 // TMMBN FCI entries.
     41 //    0                   1                   2                   3
     42 //    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
     43 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     44 //   |                              SSRC                             |
     45 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     46 //   | MxTBR Exp |  MxTBR Mantissa                 |Measured Overhead|
     47 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     48 
     49 Tmmbn::Tmmbn() = default;
     50 
     51 Tmmbn::~Tmmbn() = default;
     52 
     53 bool Tmmbn::Parse(const CommonHeader& packet) {
     54  RTC_DCHECK_EQ(packet.type(), kPacketType);
     55  RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
     56 
     57  if (packet.payload_size_bytes() < kCommonFeedbackLength) {
     58    RTC_LOG(LS_WARNING) << "Payload length " << packet.payload_size_bytes()
     59                        << " is too small for TMMBN.";
     60    return false;
     61  }
     62  size_t items_size_bytes = packet.payload_size_bytes() - kCommonFeedbackLength;
     63  if (items_size_bytes % TmmbItem::kLength != 0) {
     64    RTC_LOG(LS_WARNING) << "Payload length " << packet.payload_size_bytes()
     65                        << " is not valid for TMMBN.";
     66    return false;
     67  }
     68  ParseCommonFeedback(packet.payload());
     69  const uint8_t* next_item = packet.payload() + kCommonFeedbackLength;
     70 
     71  size_t number_of_items = items_size_bytes / TmmbItem::kLength;
     72  items_.resize(number_of_items);
     73  for (TmmbItem& item : items_) {
     74    if (!item.Parse(next_item))
     75      return false;
     76    next_item += TmmbItem::kLength;
     77  }
     78  return true;
     79 }
     80 
     81 void Tmmbn::AddTmmbr(const TmmbItem& item) {
     82  items_.push_back(item);
     83 }
     84 
     85 size_t Tmmbn::BlockLength() const {
     86  return kHeaderLength + kCommonFeedbackLength +
     87         TmmbItem::kLength * items_.size();
     88 }
     89 
     90 bool Tmmbn::Create(uint8_t* packet,
     91                   size_t* index,
     92                   size_t max_length,
     93                   PacketReadyCallback callback) const {
     94  while (*index + BlockLength() > max_length) {
     95    if (!OnBufferFull(packet, index, callback))
     96      return false;
     97  }
     98  const size_t index_end = *index + BlockLength();
     99 
    100  CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
    101               index);
    102  RTC_DCHECK_EQ(0, Rtpfb::media_ssrc());
    103  CreateCommonFeedback(packet + *index);
    104  *index += kCommonFeedbackLength;
    105  for (const TmmbItem& item : items_) {
    106    item.Create(packet + *index);
    107    *index += TmmbItem::kLength;
    108  }
    109  RTC_CHECK_EQ(index_end, *index);
    110  return true;
    111 }
    112 }  // namespace rtcp
    113 }  // namespace webrtc