RtpPacket class introduced.

webrtc/modules/rtp_rtcp/source/rtp_packet.h

+/*
+ *  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.
+ */
+#ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_H_
+
+#include <vector>
+
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/buffer.h"
+#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+
+namespace webrtc {
+struct RTPHeader;
+class RtpHeaderExtensionMap;
+class Random;
+
+namespace rtp {
+class Packet {
+ public:
+  using ExtensionType = RTPExtensionType;
+  using ExtensionManager = RtpHeaderExtensionMap;
+  static constexpr size_t kMaxExtensionHeaders = 14;
+
+  // Parse and copy given buffer into Packet.
+  bool Parse(const uint8_t* buffer, size_t size);
+
+  // Parse and move given buffer into Packet.
+  bool Parse(rtc::Buffer packet);
+
+  // Maps parsed extensions to their types to allow use of GetExtension.
+  // Used after parsing when |extensions| can't be provided until base rtp
+  // header is parsed.
+  void IdentifyExtensions(const ExtensionManager* extensions);
+
+  // Header.
+  bool Marker() const;
+  uint8_t PayloadType() const;
+  uint16_t SequenceNumber() const;
+  uint32_t Timestamp() const;
+  uint32_t Ssrc() const;
+  std::vector<uint32_t> Csrcs() const;
+
+  // TODO(danilchap): Remove this function when all code update to use RtpPacket
+  // directly. Function is there just for easier backward compatibilty.
+  void GetHeader(RTPHeader* header) const;
+
+  size_t headers_size() const;
+
+  // Payload.
+  size_t payload_size() const;
+  size_t padding_size() const;
+  const uint8_t* payload() const;
+
+  // Buffer.
+  size_t capacity() const;
+  size_t size() const;
+  const uint8_t* data() const;
+  size_t FreeCapacity() const;
+  size_t MaxPayloadSize() const;
+
+  // Reset fields and buffer.
+  void Clear();
+
+  // Header setters.
+  void CopyHeader(const Packet& packet);
+  void SetMarker(bool marker_bit);
+  void SetPayloadType(uint8_t payload_type);
+  void SetSequenceNumber(uint16_t seq_no);
+  void SetTimestamp(uint32_t timestamp);
+  void SetSsrc(uint32_t ssrc);
+
+  // Writes csrc list. Assumes:
+  // a) There is enough room left in buffer.
+  // b) Extension headers, payload or padding data has not already been added.
+  void SetCsrcs(const std::vector<uint32_t>& csrcs);
+
+  // Header extensions.
+  template <typename Extension, typename... Values>
+  bool GetExtension(Values...) const;
+
+  template <typename Extension, typename... Values>
+  bool SetExtension(Values...);
+
+  template <typename Extension>
+  bool ReserveExtension();
+
+  // Reserve size_bytes for payload. Returns nullptr on failure.
+  uint8_t* AllocatePayload(size_t size_bytes);
+  void SetPayloadSize(size_t size_bytes);
+  bool SetPadding(uint8_t size_bytes, Random* random);
+
+ protected:
+  // |extensions| required for SetExtension/ReserveExtension functions during
+  // packet creating and used if available in Parse function.
+  // Adding and getting extensions will fail until |extensions| is
+  // provided via constructor or IdentifyExtensions function.
+  explicit Packet(const ExtensionManager* extensions);
+  Packet(const ExtensionManager* extensions, size_t capacity);
+  virtual ~Packet();
+
+ private:
+  struct ExtensionInfo {
+    ExtensionType type;
+    uint16_t offset;
+    uint8_t length;
+  };
+
+  // Helper function for Parse. Fill header fields using data in given buffer,
+  // but does not touch packet own buffer, leaving packet in invalid state.
+  bool ParseBuffer(const uint8_t* buffer, size_t size);
+
+  // Find an extension based on the type field of the parameter.
+  // If found, length field would be validated, the offset field will be set
+  // and true returned,
+  // otherwise the parameter will be unchanged and false is returned.
+  bool FindExtension(ExtensionType type,
+                     uint8_t length,
+                     uint16_t* offset) const;
+
+  // Find or allocate an extension, based on the type field of the parameter.
+  // If found, the length field be checked against what is already registered
+  // and the offset field will be set, then true is returned. If allocated, the
+  // length field will be used for allocation and the offset update to indicate
+  // position, the true is returned.
+  // If not found and allocations fails, false is returned and parameter remains
+  // unchanged.
+  bool AllocateExtension(ExtensionType type, uint8_t length, uint16_t* offset);
+
+  uint8_t* WriteAt(size_t offset);
+  void WriteAt(size_t offset, uint8_t byte);
+
+  const ExtensionManager* extensions_;
+
+  // Header.
+  bool marker_;
+  uint8_t payload_type_;
+  uint8_t padding_size_;
+  uint16_t sequence_number_;
+  uint32_t timestamp_;
+  uint32_t ssrc_;
+  size_t payload_offset_;  // Match header size with csrcs and extensions.
+  size_t payload_size_;
+
+  uint8_t num_extensions_ = 0;
+  ExtensionInfo extension_entries_[kMaxExtensionHeaders];
+  uint16_t extensions_size_ = 0;  // Unaligned.
+  rtc::Buffer buffer_;
+
+  RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(Packet);
+};
+
+template <typename Extension, typename... Values>
+bool Packet::GetExtension(Values... values) const {
+  uint16_t offset = 0;
+  if (!FindExtension(Extension::kId, Extension::kValueSizeBytes, &offset))
+    return false;
+  return Extension::Parse(data() + offset, values...);
+}
+
+template <typename Extension, typename... Values>
+bool Packet::SetExtension(Values... values) {
+  uint16_t offset = 0;
+  if (!AllocateExtension(Extension::kId, Extension::kValueSizeBytes, &offset))
+    return false;
+  return Extension::Write(WriteAt(offset), values...);
+}
+
+template <typename Extension>
+bool Packet::ReserveExtension() {
+  uint16_t offset = 0;
+  if (!AllocateExtension(Extension::kId, Extension::kValueSizeBytes, &offset))
+    return false;
+  memset(WriteAt(offset), 0, Extension::kValueSizeBytes);
+  return true;
+}
+}  // namespace rtp
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_H_