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/*
* Copyright (c) 2015 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 "modules/rtp_rtcp/source/rtcp_packet/bye.h"
#include <string.h>
#include <cstdint>
#include <string>
#include <utility>
#include <vector>
#include "absl/strings/string_view.h"
#include "modules/rtp_rtcp/source/byte_io.h"
#include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
namespace webrtc {
namespace rtcp {
// 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 ...
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Bye::Bye() = default;
Bye::~Bye() = default;
bool Bye::Parse(const CommonHeader& packet) {
RTC_DCHECK_EQ(packet.type(), kPacketType);
const uint8_t src_count = packet.count();
// Validate packet.
if (packet.payload_size_bytes() < 4u * src_count) {
RTC_LOG(LS_WARNING)
<< "Packet is too small to contain CSRCs it promise to have.";
return false;
}
const uint8_t* const payload = packet.payload();
bool has_reason = packet.payload_size_bytes() > 4u * src_count;
uint8_t reason_length = 0;
if (has_reason) {
reason_length = payload[4u * src_count];
if (packet.payload_size_bytes() - 4u * src_count < 1u + reason_length) {
RTC_LOG(LS_WARNING) << "Invalid reason length: " << reason_length;
return false;
}
}
// Once sure packet is valid, copy values.
if (src_count == 0) { // A count value of zero is valid, but useless.
SetSenderSsrc(0);
csrcs_.clear();
} else {
SetSenderSsrc(ByteReader<uint32_t>::ReadBigEndian(payload));
csrcs_.resize(src_count - 1);
for (size_t i = 1; i < src_count; ++i)
csrcs_[i - 1] = ByteReader<uint32_t>::ReadBigEndian(&payload[4 * i]);
}
if (has_reason) {
reason_.assign(reinterpret_cast<const char*>(&payload[4u * src_count + 1]),
reason_length);
} else {
reason_.clear();
}
return true;
}
bool Bye::Create(uint8_t* packet,
size_t* index,
size_t max_length,
PacketReadyCallback callback) const {
while (*index + BlockLength() > max_length) {
if (!OnBufferFull(packet, index, callback))
return false;
}
const size_t index_end = *index + BlockLength();
CreateHeader(1 + csrcs_.size(), kPacketType, HeaderLength(), packet, index);
// Store srcs of the leaving clients.
ByteWriter<uint32_t>::WriteBigEndian(&packet[*index], sender_ssrc());
*index += sizeof(uint32_t);
for (uint32_t csrc : csrcs_) {
ByteWriter<uint32_t>::WriteBigEndian(&packet[*index], csrc);
*index += sizeof(uint32_t);
}
// Store the reason to leave.
if (!reason_.empty()) {
uint8_t reason_length = static_cast<uint8_t>(reason_.size());
packet[(*index)++] = reason_length;
memcpy(&packet[*index], reason_.data(), reason_length);
*index += reason_length;
// Add padding bytes if needed.
size_t bytes_to_pad = index_end - *index;
RTC_DCHECK_LE(bytes_to_pad, 3);
if (bytes_to_pad > 0) {
memset(&packet[*index], 0, bytes_to_pad);
*index += bytes_to_pad;
}
}
RTC_DCHECK_EQ(index_end, *index);
return true;
}
bool Bye::SetCsrcs(std::vector<uint32_t> csrcs) {
if (csrcs.size() > kMaxNumberOfCsrcs) {
RTC_LOG(LS_WARNING) << "Too many CSRCs for Bye packet.";
return false;
}
csrcs_ = std::move(csrcs);
return true;
}
void Bye::SetReason(absl::string_view reason) {
RTC_DCHECK_LE(reason.size(), 0xffu);
reason_ = std::string(reason);
}
size_t Bye::BlockLength() const {
size_t src_count = (1 + csrcs_.size());
size_t reason_size_in_32bits = reason_.empty() ? 0 : (reason_.size() / 4 + 1);
return kHeaderLength + 4 * (src_count + reason_size_in_32bits);
}
} // namespace rtcp
} // namespace webrtc
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