100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
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/*
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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/rtp_rtcp/source/rtcp_packet.h"
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#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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namespace rtcp {
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constexpr size_t RtcpPacket::kHeaderLength;
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rtc::Buffer RtcpPacket::Build() const {
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rtc::Buffer packet(BlockLength());
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size_t length = 0;
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bool created = Create(packet.data(), &length, packet.capacity(), nullptr);
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RTC_DCHECK(created) << "Invalid packet is not supported.";
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RTC_DCHECK_EQ(length, packet.size())
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<< "BlockLength mispredicted size used by Create";
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return packet;
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}
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bool RtcpPacket::Build(size_t max_length, PacketReadyCallback callback) const {
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RTC_CHECK_LE(max_length, IP_PACKET_SIZE);
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uint8_t buffer[IP_PACKET_SIZE];
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size_t index = 0;
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if (!Create(buffer, &index, max_length, callback))
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return false;
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return OnBufferFull(buffer, &index, callback);
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}
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bool RtcpPacket::OnBufferFull(uint8_t* packet,
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size_t* index,
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PacketReadyCallback callback) const {
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if (*index == 0)
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return false;
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RTC_DCHECK(callback) << "Fragmentation not supported.";
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callback(rtc::ArrayView<const uint8_t>(packet, *index));
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*index = 0;
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return true;
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}
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size_t RtcpPacket::HeaderLength() const {
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size_t length_in_bytes = BlockLength();
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RTC_DCHECK_GT(length_in_bytes, 0);
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RTC_DCHECK_EQ(length_in_bytes % 4, 0)
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<< "Padding must be handled by each subclass.";
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// Length in 32-bit words without common header.
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return (length_in_bytes - kHeaderLength) / 4;
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}
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// From RFC 3550, RTP: A Transport Protocol for Real-Time Applications.
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//
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// RTP header format.
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// 0 1 2 3
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// 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
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// |V=2|P| RC/FMT | PT | length |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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void RtcpPacket::CreateHeader(
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size_t count_or_format, // Depends on packet type.
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uint8_t packet_type,
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size_t length,
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uint8_t* buffer,
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size_t* pos) {
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CreateHeader(count_or_format, packet_type, length, /*padding=*/false, buffer,
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pos);
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}
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void RtcpPacket::CreateHeader(
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size_t count_or_format, // Depends on packet type.
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uint8_t packet_type,
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size_t length,
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bool padding,
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uint8_t* buffer,
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size_t* pos) {
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RTC_DCHECK_LE(length, 0xffffU);
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RTC_DCHECK_LE(count_or_format, 0x1f);
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constexpr uint8_t kVersionBits = 2 << 6;
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uint8_t padding_bit = padding ? 1 << 5 : 0;
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buffer[*pos + 0] =
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kVersionBits | padding_bit | static_cast<uint8_t>(count_or_format);
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buffer[*pos + 1] = packet_type;
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buffer[*pos + 2] = (length >> 8) & 0xff;
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buffer[*pos + 3] = length & 0xff;
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*pos += kHeaderLength;
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}
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} // namespace rtcp
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} // namespace webrtc
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