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/*
* Copyright (c) 2016 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/sdes.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.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 {
// 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 ...
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
namespace {
const uint8_t kTerminatorTag = 0;
const uint8_t kCnameTag = 1;
size_t ChunkSize(const Sdes::Chunk& chunk) {
// Chunk:
// SSRC/CSRC (4 bytes) | CNAME=1 (1 byte) | length (1 byte) | cname | padding.
size_t chunk_payload_size = 4 + 1 + 1 + chunk.cname.size();
size_t padding_size = 4 - (chunk_payload_size % 4); // Minimum 1.
return chunk_payload_size + padding_size;
}
} // namespace
Sdes::Sdes() : block_length_(RtcpPacket::kHeaderLength) {}
Sdes::~Sdes() {}
bool Sdes::Parse(const CommonHeader& packet) {
RTC_DCHECK_EQ(packet.type(), kPacketType);
uint8_t number_of_chunks = packet.count();
std::vector<Chunk> chunks; // Read chunk into temporary array, so that in
// case of an error original array would stay
// unchanged.
size_t block_length = kHeaderLength;
if (packet.payload_size_bytes() % 4 != 0) {
RTC_LOG(LS_WARNING) << "Invalid payload size "
<< packet.payload_size_bytes()
<< " bytes for a valid Sdes packet. Size should be"
" multiple of 4 bytes";
}
const uint8_t* const payload_end =
packet.payload() + packet.payload_size_bytes();
const uint8_t* looking_at = packet.payload();
chunks.resize(number_of_chunks);
for (size_t i = 0; i < number_of_chunks;) {
// Each chunk consumes at least 8 bytes.
if (payload_end - looking_at < 8) {
RTC_LOG(LS_WARNING) << "Not enough space left for chunk #" << (i + 1);
return false;
}
chunks[i].ssrc = ByteReader<uint32_t>::ReadBigEndian(looking_at);
looking_at += sizeof(uint32_t);
bool cname_found = false;
uint8_t item_type;
while ((item_type = *(looking_at++)) != kTerminatorTag) {
if (looking_at >= payload_end) {
RTC_LOG(LS_WARNING)
<< "Unexpected end of packet while reading chunk #" << (i + 1)
<< ". Expected to find size of the text.";
return false;
}
uint8_t item_length = *(looking_at++);
const size_t kTerminatorSize = 1;
if (looking_at + item_length + kTerminatorSize > payload_end) {
RTC_LOG(LS_WARNING)
<< "Unexpected end of packet while reading chunk #" << (i + 1)
<< ". Expected to find text of size " << item_length;
return false;
}
if (item_type == kCnameTag) {
if (cname_found) {
RTC_LOG(LS_WARNING)
<< "Found extra CNAME for same ssrc in chunk #" << (i + 1);
return false;
}
cname_found = true;
chunks[i].cname.assign(reinterpret_cast<const char*>(looking_at),
item_length);
}
looking_at += item_length;
}
if (cname_found) {
// block_length calculates length of the packet that would be generated by
// Build/Create functions. Adjust it same way WithCName function does.
block_length += ChunkSize(chunks[i]);
++i;
} else {
// RFC states CNAME item is mandatory.
// But same time it allows chunk without items.
// So while parsing, ignore all chunks without cname,
// but do not fail the parse.
RTC_LOG(LS_WARNING) << "CNAME not found for ssrc " << chunks[i].ssrc;
--number_of_chunks;
chunks.resize(number_of_chunks);
}
// Adjust to 32bit boundary.
looking_at += (payload_end - looking_at) % 4;
}
chunks_ = std::move(chunks);
block_length_ = block_length;
return true;
}
bool Sdes::AddCName(uint32_t ssrc, absl::string_view cname) {
RTC_DCHECK_LE(cname.length(), 0xffu);
if (chunks_.size() >= kMaxNumberOfChunks) {
RTC_LOG(LS_WARNING) << "Max SDES chunks reached.";
return false;
}
Chunk chunk;
chunk.ssrc = ssrc;
chunk.cname = std::string(cname);
chunks_.push_back(chunk);
block_length_ += ChunkSize(chunk);
return true;
}
size_t Sdes::BlockLength() const {
return block_length_;
}
bool Sdes::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(chunks_.size(), kPacketType, HeaderLength(), packet, index);
for (const Sdes::Chunk& chunk : chunks_) {
ByteWriter<uint32_t>::WriteBigEndian(&packet[*index + 0], chunk.ssrc);
ByteWriter<uint8_t>::WriteBigEndian(&packet[*index + 4], kCnameTag);
ByteWriter<uint8_t>::WriteBigEndian(
&packet[*index + 5], static_cast<uint8_t>(chunk.cname.size()));
memcpy(&packet[*index + 6], chunk.cname.data(), chunk.cname.size());
*index += (6 + chunk.cname.size());
// 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.
size_t padding_size = 4 - ((6 + chunk.cname.size()) % 4);
const int kPadding = 0;
memset(packet + *index, kPadding, padding_size);
*index += padding_size;
}
RTC_CHECK_EQ(*index, index_end);
return true;
}
} // namespace rtcp
} // namespace webrtc
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