RtpPacket class introduced.

webrtc/modules/rtp_rtcp/source/rtp_packet.cc

+/*
+ *  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 "webrtc/modules/rtp_rtcp/source/rtp_packet.h"
+
+#include <cstring>
+
+#include "webrtc/base/checks.h"
+#include "webrtc/base/logging.h"
+#include "webrtc/base/random.h"
+#include "webrtc/common_types.h"
+#include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
+#include "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"
+#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
+
+namespace webrtc {
+namespace rtp {
+namespace {
+constexpr size_t kFixedHeaderSize = 12;
+constexpr uint8_t kRtpVersion = 2;
+constexpr uint16_t kOneByteExtensionId = 0xBEDE;
+constexpr size_t kOneByteHeaderSize = 1;
+constexpr size_t kDefaultPacketSize = 1500;
+}  // namespace
+//  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|X|  CC   |M|     PT      |       sequence number         |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |                           timestamp                           |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |           synchronization source (SSRC) identifier            |
+// +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+// |            Contributing source (CSRC) identifiers             |
+// |                             ....                              |
+// +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+// |One-byte eXtensions id = 0xbede|       length in 32bits        |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |                          Extensions                           |
+// |                             ....                              |
+// +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+// |                           Payload                             |
+// |             ....              :  padding...                   |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |               padding         | Padding size  |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+Packet::Packet(const ExtensionManager* extensions)
+    : extensions_(extensions), buffer_(kDefaultPacketSize) {
+  Clear();
+}
+
+Packet::Packet(const ExtensionManager* extensions, size_t capacity)
+    : extensions_(extensions), buffer_(capacity) {
+  RTC_DCHECK_GE(capacity, kFixedHeaderSize);
+  Clear();
+}
+
+Packet::~Packet() {}
+
+void Packet::IdentifyExtensions(const ExtensionManager* extensions) {
+  RTC_DCHECK(extensions);
+  extensions_ = extensions;
+  for (size_t i = 0; i < num_extensions_; ++i) {
+    uint8_t id = data()[extension_entries_[i].offset - 1] >> 4;
+    extension_entries_[i].type = extensions_->GetType(id);
+  }
+}
+
+bool Packet::Parse(const uint8_t* buffer, size_t buffer_size) {
+  if (!ParseBuffer(buffer, buffer_size)) {
+    Clear();
+    return false;
+  }
+  RTC_DCHECK_EQ(size(), buffer_size);
+  buffer_.SetData(buffer, buffer_size);
+  return true;
+}
+
+bool Packet::Parse(rtc::Buffer buffer) {
+  if (!ParseBuffer(buffer.data(), buffer.size())) {
+    Clear();
+    return false;
+  }
+  RTC_DCHECK_EQ(size(), buffer.size());
+  buffer_ = std::move(buffer);
+  return true;
+}
+
+bool Packet::Marker() const {
+  RTC_DCHECK_EQ(marker_, (data()[1] & 0x80) != 0);
+  return marker_;
+}
+
+uint8_t Packet::PayloadType() const {
+  RTC_DCHECK_EQ(payload_type_, data()[1] & 0x7f);
+  return payload_type_;
+}
+
+uint16_t Packet::SequenceNumber() const {
+  RTC_DCHECK_EQ(sequence_number_,
+                ByteReader<uint16_t>::ReadBigEndian(data() + 2));
+  return sequence_number_;
+}
+
+uint32_t Packet::Timestamp() const {
+  RTC_DCHECK_EQ(timestamp_, ByteReader<uint32_t>::ReadBigEndian(data() + 4));
+  return timestamp_;
+}
+
+uint32_t Packet::Ssrc() const {
+  RTC_DCHECK_EQ(ssrc_, ByteReader<uint32_t>::ReadBigEndian(data() + 8));
+  return ssrc_;
+}
+
+std::vector<uint32_t> Packet::Csrcs() const {
+  size_t num_csrc = data()[0] & 0x0F;
+  RTC_DCHECK_GE(capacity(), kFixedHeaderSize + num_csrc * 4);
+  std::vector<uint32_t> csrcs(num_csrc);
+  for (size_t i = 0; i < num_csrc; ++i) {
+    csrcs[i] =
+        ByteReader<uint32_t>::ReadBigEndian(&data()[kFixedHeaderSize + i * 4]);
+  }
+  return csrcs;
+}
+
+void Packet::GetHeader(RTPHeader* header) const {
+  header->markerBit = Marker();
+  header->payloadType = PayloadType();
+  header->sequenceNumber = SequenceNumber();
+  header->timestamp = Timestamp();
+  header->ssrc = Ssrc();
+  std::vector<uint32_t> csrcs = Csrcs();
+  header->numCSRCs = csrcs.size();
+  for (size_t i = 0; i < csrcs.size(); ++i) {
+    header->arrOfCSRCs[i] = csrcs[i];
+  }
+  header->paddingLength = padding_size();
+  header->headerLength = headers_size();
+  header->payload_type_frequency = 0;
+  header->extension.hasTransmissionTimeOffset =
+      GetExtension<TransmissionOffset>(
+          &header->extension.transmissionTimeOffset);
+  header->extension.hasAbsoluteSendTime =
+      GetExtension<AbsoluteSendTime>(&header->extension.absoluteSendTime);
+  header->extension.hasTransportSequenceNumber =
+      GetExtension<TransportSequenceNumber>(
+          &header->extension.transportSequenceNumber);
+  header->extension.hasAudioLevel = GetExtension<AudioLevel>(
+      &header->extension.voiceActivity, &header->extension.audioLevel);
+  header->extension.hasVideoRotation =
+      GetExtension<VideoOrientation>(&header->extension.videoRotation);
+}
+
+size_t Packet::headers_size() const {
+  return payload_offset_;
+}
+
+size_t Packet::payload_size() const {
+  return payload_size_;
+}
+
+size_t Packet::padding_size() const {
+  return padding_size_;
+}
+
+const uint8_t* Packet::payload() const {
+  return data() + payload_offset_;
+}
+
+size_t Packet::capacity() const {
+  return buffer_.size();
+}
+
+size_t Packet::size() const {
+  return payload_offset_ + payload_size_ + padding_size_;
+}
+
+const uint8_t* Packet::data() const {
+  return buffer_.data();
+}
+
+size_t Packet::FreeCapacity() const {
+  return capacity() - size();
+}
+
+size_t Packet::MaxPayloadSize() const {
+  return capacity() - payload_offset_;
+}
+
+void Packet::CopyHeader(const Packet& packet) {
+  RTC_DCHECK_GE(capacity(), packet.headers_size());
+
+  marker_ = packet.marker_;
+  payload_type_ = packet.payload_type_;
+  sequence_number_ = packet.sequence_number_;
+  timestamp_ = packet.timestamp_;
+  ssrc_ = packet.ssrc_;
+  payload_offset_ = packet.payload_offset_;
+  num_extensions_ = packet.num_extensions_;
+  for (size_t i = 0; i < num_extensions_; ++i) {
+    extension_entries_[i] = packet.extension_entries_[i];
+  }
+  extensions_size_ = packet.extensions_size_;
+  buffer_.SetData(packet.data(), packet.headers_size());
+  // Reset payload and padding.
+  payload_size_ = 0;
+  padding_size_ = 0;
+}
+
+void Packet::SetMarker(bool marker_bit) {
+  marker_ = marker_bit;
+  if (marker_) {
+    WriteAt(1, data()[1] | 0x80);
+  } else {
+    WriteAt(1, data()[1] & 0x7F);
+  }
+}
+
+void Packet::SetPayloadType(uint8_t payload_type) {
+  RTC_DCHECK_LE(payload_type, 0x7Fu);
+  payload_type_ = payload_type;
+  WriteAt(1, (data()[1] & 0x80) | payload_type);
+}
+
+void Packet::SetSequenceNumber(uint16_t seq_no) {
+  sequence_number_ = seq_no;
+  ByteWriter<uint16_t>::WriteBigEndian(WriteAt(2), seq_no);
+}
+
+void Packet::SetTimestamp(uint32_t timestamp) {
+  timestamp_ = timestamp;
+  ByteWriter<uint32_t>::WriteBigEndian(WriteAt(4), timestamp);
+}
+
+void Packet::SetSsrc(uint32_t ssrc) {
+  ssrc_ = ssrc;
+  ByteWriter<uint32_t>::WriteBigEndian(WriteAt(8), ssrc);
+}
+
+void Packet::SetCsrcs(const std::vector<uint32_t>& csrcs) {
+  RTC_DCHECK_EQ(num_extensions_, 0u);
+  RTC_DCHECK_EQ(payload_size_, 0u);
+  RTC_DCHECK_EQ(padding_size_, 0u);
+  RTC_DCHECK_LE(csrcs.size(), 0x0fu);
+  RTC_DCHECK_LE(kFixedHeaderSize + 4 * csrcs.size(), capacity());
+  payload_offset_ = kFixedHeaderSize + 4 * csrcs.size();
+  WriteAt(0, (data()[0] & 0xF0) | csrcs.size());
+  size_t offset = kFixedHeaderSize;
+  for (uint32_t csrc : csrcs) {
+    ByteWriter<uint32_t>::WriteBigEndian(WriteAt(offset), csrc);
+    offset += 4;
+  }
+}
+
+uint8_t* Packet::AllocatePayload(size_t size_bytes) {
+  RTC_DCHECK_EQ(padding_size_, 0u);
+  if (payload_offset_ + size_bytes > capacity()) {
+    LOG(LS_WARNING) << "Cannot set payload, not enough space in buffer.";
+    return nullptr;
+  }
+  payload_size_ = size_bytes;
+  return WriteAt(payload_offset_);
+}
+
+void Packet::SetPayloadSize(size_t size_bytes) {
+  RTC_DCHECK_EQ(padding_size_, 0u);
+  RTC_DCHECK_LE(size_bytes, payload_size_);
+  payload_size_ = size_bytes;
+}
+
+bool Packet::SetPadding(uint8_t size_bytes, Random* random) {
+  RTC_DCHECK(random);
+  if (payload_offset_ + payload_size_ + size_bytes > capacity()) {
+    LOG(LS_WARNING) << "Cannot set padding size " << size_bytes << ", only "
+                    << (capacity() - payload_offset_ - payload_size_)
+                    << " bytes left in buffer.";
+    return false;
+  }
+  padding_size_ = size_bytes;
+  if (padding_size_ > 0) {
+    size_t padding_offset = payload_offset_ + payload_size_;
+    size_t padding_end = padding_offset + padding_size_;
+    for (size_t offset = padding_offset; offset < padding_end - 1; ++offset) {
+      WriteAt(offset, random->Rand<uint8_t>());
+    }
+    WriteAt(padding_end - 1, padding_size_);
+    WriteAt(0, data()[0] | 0x20);  // Set padding bit.
+  } else {
+    WriteAt(0, data()[0] & ~0x20);  // Clear padding bit.
+  }
+  return true;
+}
+
+void Packet::Clear() {
+  marker_ = false;
+  payload_type_ = 0;
+  sequence_number_ = 0;
+  timestamp_ = 0;
+  ssrc_ = 0;
+  payload_offset_ = kFixedHeaderSize;
+  payload_size_ = 0;
+  padding_size_ = 0;
+  num_extensions_ = 0;
+  extensions_size_ = 0;
+
+  memset(WriteAt(0), 0, kFixedHeaderSize);
+  WriteAt(0, kRtpVersion << 6);
+}
+
+bool Packet::ParseBuffer(const uint8_t* buffer, size_t size) {
+  if (size < kFixedHeaderSize) {
+    return false;
+  }
+  const uint8_t version = buffer[0] >> 6;
+  if (version != kRtpVersion) {
+    return false;
+  }
+  const bool has_padding = (buffer[0] & 0x20) != 0;
+  const bool has_extension = (buffer[0] & 0x10) != 0;
+  const uint8_t number_of_crcs = buffer[0] & 0x0f;
+  marker_ = (buffer[1] & 0x80) != 0;
+  payload_type_ = buffer[1] & 0x7f;
+
+  sequence_number_ = ByteReader<uint16_t>::ReadBigEndian(&buffer[2]);
+  timestamp_ = ByteReader<uint32_t>::ReadBigEndian(&buffer[4]);
+  ssrc_ = ByteReader<uint32_t>::ReadBigEndian(&buffer[8]);
+  if (size < kFixedHeaderSize + number_of_crcs * 4) {
+    return false;
+  }
+  payload_offset_ = kFixedHeaderSize + number_of_crcs * 4;
+
+  if (has_padding) {
+    padding_size_ = buffer[size - 1];
+    if (padding_size_ == 0) {
+      LOG(LS_WARNING) << "Padding was set, but padding size is zero";
+      return false;
+    }
+  } else {
+    padding_size_ = 0;
+  }
+
+  num_extensions_ = 0;
+  extensions_size_ = 0;
+  if (has_extension) {
+    /* RTP header extension, 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
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |      defined by profile       |           length              |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                        header extension                       |
+    |                             ....                              |
+    */
+    size_t extension_offset = payload_offset_ + 4;
+    if (extension_offset > size) {
+      return false;
+    }
+    uint16_t profile =
+        ByteReader<uint16_t>::ReadBigEndian(&buffer[payload_offset_]);
+    size_t extensions_capacity =
+        ByteReader<uint16_t>::ReadBigEndian(&buffer[payload_offset_ + 2]);
+    extensions_capacity *= 4;
+    if (extension_offset + extensions_capacity > size) {
+      return false;
+    }
+    if (profile != kOneByteExtensionId) {
+      LOG(LS_WARNING) << "Unsupported rtp extension " << profile;
+    } else {
+      constexpr uint8_t kPaddingId = 0;
+      constexpr uint8_t kReservedId = 15;
+      while (extensions_size_ + kOneByteHeaderSize < extensions_capacity) {
+        uint8_t id = buffer[extension_offset + extensions_size_] >> 4;
+        if (id == kReservedId) {
+          break;
+        } else if (id == kPaddingId) {
+          extensions_size_++;
+          continue;
+        }
+        uint8_t length =
+            1 + (buffer[extension_offset + extensions_size_] & 0xf);
+        extensions_size_ += kOneByteHeaderSize;
+        if (num_extensions_ >= kMaxExtensionHeaders) {
+          LOG(LS_WARNING) << "Too many extensions.";
+          return false;
+        }
+        extension_entries_[num_extensions_].type =
+            extensions_ ? extensions_->GetType(id)
+                        : ExtensionManager::kInvalidType;
+        extension_entries_[num_extensions_].length = length;
+        extension_entries_[num_extensions_].offset =
+            extension_offset + extensions_size_;
+        num_extensions_++;
+        extensions_size_ += length;
+      }
+    }
+    payload_offset_ = extension_offset + extensions_capacity;
+  }
+
+  if (payload_offset_ + padding_size_ > size) {
+    return false;
+  }
+  payload_size_ = size - payload_offset_ - padding_size_;
+  return true;
+}
+
+bool Packet::FindExtension(ExtensionType type,
+                           uint8_t length,
+                           uint16_t* offset) const {
+  RTC_DCHECK(offset);
+  for (size_t i = 0; i < num_extensions_; ++i) {
+    if (extension_entries_[i].type == type) {
+      RTC_CHECK_EQ(length, extension_entries_[i].length)
+          << "Length mismatch for extension '" << type << "'"
+          << "should be " << length << ", received "
+          << extension_entries_[i].length;
+      *offset = extension_entries_[i].offset;
+      return true;
+    }
+  }
+  return false;
+}
+
+bool Packet::AllocateExtension(ExtensionType type,
+                               uint8_t length,
+                               uint16_t* offset) {
+  if (!extensions_) {
+    return false;
+  }
+  if (FindExtension(type, length, offset)) {
+    return true;
+  }
+
+  // Can't add new extension after payload/padding was set.
+  if (payload_size_ > 0) {
+    return false;
+  }
+  if (padding_size_ > 0) {
+    return false;
+  }
+
+  uint8_t extension_id = extensions_->GetId(type);
+  if (extension_id == ExtensionManager::kInvalidId) {
+    return false;
+  }
+  RTC_DCHECK_GT(length, 0u);
+  RTC_DCHECK_LE(length, 16u);
+
+  size_t num_csrc = data()[0] & 0x0F;
+  size_t extensions_offset = kFixedHeaderSize + (num_csrc * 4) + 4;
+  if (extensions_offset + extensions_size_ + kOneByteHeaderSize + length >
+      capacity()) {
+    LOG(LS_WARNING) << "Extension cannot be registered: "
+                       "Not enough space left in buffer.";
+    return false;
+  }
+
+  uint16_t new_extensions_size =
+      extensions_size_ + kOneByteHeaderSize + length;
+  uint16_t extensions_words =
+      (new_extensions_size + 3) / 4;  // Wrap up to 32bit.
+
+  // All checks passed, write down the extension.
+  if (num_extensions_ == 0) {
+    RTC_DCHECK_EQ(payload_offset_, kFixedHeaderSize + (num_csrc * 4));
+    RTC_DCHECK_EQ(extensions_size_, 0);
+    WriteAt(0, data()[0] | 0x10);  // Set extension bit.
+    // Profile specific ID always set to OneByteExtensionHeader.
+    ByteWriter<uint16_t>::WriteBigEndian(WriteAt(extensions_offset - 4),
+                                         kOneByteExtensionId);
+  }
+
+  WriteAt(extensions_offset + extensions_size_,
+          (extension_id << 4) | (length - 1));
+  RTC_DCHECK(num_extensions_ < kMaxExtensionHeaders);
+  extension_entries_[num_extensions_].type = type;
+  extension_entries_[num_extensions_].length = length;
+  *offset = extensions_offset + kOneByteHeaderSize + extensions_size_;
+  extension_entries_[num_extensions_].offset = *offset;
+  ++num_extensions_;
+  extensions_size_ = new_extensions_size;
+
+  // Update header length field.
+  ByteWriter<uint16_t>::WriteBigEndian(WriteAt(extensions_offset - 2),
+                                       extensions_words);
+  // Fill extension padding place with zeroes.
+  size_t extension_padding_size = 4 * extensions_words - extensions_size_;
+  memset(WriteAt(extensions_offset + extensions_size_), 0,
+         extension_padding_size);
+  payload_offset_ = extensions_offset + 4 * extensions_words;
+  return true;
+}
+
+uint8_t* Packet::WriteAt(size_t offset) {
+  return buffer_.data() + offset;
+}
+
+void Packet::WriteAt(size_t offset, uint8_t byte) {
+  buffer_.data()[offset] = byte;
+}
+
+}  // namespace rtp
+}  // namespace webrtc