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/base/checks.h"
+#include "webrtc/common_types.h"
+#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+#include "webrtc/system_wrappers/include/ntp_time.h"
+
+namespace webrtc {
+class RtpHeaderExtensionMap;
+class Random;
+
+namespace rtp {
+class Packet {
+ public:
+  using ExtensionType = RTPExtensionType;
+  using ExtensionManager = RtpHeaderExtensionMap;
+  static const size_t kMaxExtensionHeaders = 14;
+
+  bool Parse(const uint8_t* buffer, size_t size);
+  bool Parse(rtc::Buffer packet);
+
+  // 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;
+  // Header extensions.
+  template <typename Extension, typename... Values>
+  bool GetExtension(Values...) const;
+  size_t HeadersSize() const;
+  // Payload.
+  size_t PayloadSize() const;
+  size_t PaddingSize() const;
+  const uint8_t* Payload() const;
+  // Buffer.
+  size_t capacity() const;
+  size_t size() const;
+  const uint8_t* data() const;
+  size_t FreeCapacity() const { return capacity() - size(); }
+  size_t MaxPayloadSize() const { return capacity() - payload_offset_; }
+
+  // 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 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:
+  explicit Packet(const ExtensionManager* extensions);

[terelius, 2016/04/13 13:17:00]

So you have to know what header extensions are used before you create the packet
object? I wonder if this could be an issue. If you don't know the SSRC of the
packet, do you create a temporary packet object with no registered extensions
and copy the buffer there just to get the SSRC?

[danilchap, 2016/04/13 16:18:34]

Good point.
Adjusted. Added function SetExtensionManager that can be called after packet is
parsed.

+  Packet(const ExtensionManager* extensions, size_t capacity);
+  virtual ~Packet();
+
+ private:
+  struct ExtensionInfo {
+    ExtensionType type;
+    uint16_t offset;
+    uint8_t length;
+  };
+  // Tries to Parse data in given buffer.
+  // Does not touch packet own buffer, leaving packet in desync state on return.

[terelius, 2016/04/13 13:17:00]

I don't understand what this comment means. Updates all header fields of the
Packet object, but does not copy the packet data to the buffer?

Which functions am I allowed to call after ParseBuffer()?

[danilchap, 2016/04/13 16:18:34]

this function is private, you shouldn't call it all, but instead use one of the
Parse functions above.
both of them call this function and then ensure buffer match header fields.
I try to make more clear this helper function leave Packet in invalid state on
return.

+  bool ParseBuffer(const uint8_t* buffer, size_t size);
+  // Find and extension, based on the type field of the parameter.

[philipel, 2016/04/13 12:01:19]

Find an extension

[danilchap, 2016/04/13 16:18:34]

Done.

+  // 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 paramter remains

[terelius, 2016/04/13 13:17:00]

nit: parameter

[danilchap, 2016/04/13 16:18:34]

Done.

+  // unchanged.
+  bool AllocateExtension(ExtensionType type, uint8_t length, uint16_t* offset);
+
+  uint8_t* WriteAt(size_t offset) { return buffer_.data() + offset; }

[philipel, 2016/04/13 12:01:19]

Move implementation to .cc file.

[danilchap, 2016/04/13 16:18:34]

Done.

+  void WriteAt(size_t offset, uint8_t byte) { buffer_.data()[offset] = byte; }

[philipel, 2016/04/13 12:01:19]

Ditto.

[danilchap, 2016/04/13 16:18:34]

Done.

+
+  const ExtensionManager* const 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_COPY_AND_ASSIGN(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
+
+// Class to hold rtp packet with metadata for sender side.
+class RtpPacket : public rtp::Packet {

[philipel, 2016/04/13 12:01:19]

Rename to SendRtpPacket or something that indicates that this is the class to
use for sending an rtp packet.

[danilchap, 2016/04/13 16:18:34]

Done.

+ public:
+  explicit RtpPacket(const ExtensionManager* extensions) : Packet(extensions) {}
+  RtpPacket(const ExtensionManager* extensions, size_t capacity)
+      : Packet(extensions, capacity) {}

[philipel, 2016/04/13 12:01:19]

Why is the implementation for RtpPacket and ReceiveRtpPacket in the .h file?

[danilchap, 2016/04/13 16:18:34]

Definition is here for no good reason, moved to own files.
Implementation is in .h because there is practically no implementation: all own
functions are trivial accessors,
constructor forwards directly to rtp::Packet constructor. There is no plan to
add any non-trivial function.

[philipel, 2016/04/14 10:32:02]

Acknowledged.

+
+  // Time in local time base as close as it can to frame capture time.
+  int64_t capture_time_ms() const { return capture_time_ms_; }
+  void set_capture_time_ms(int64_t time) { capture_time_ms_ = time; }
+
+ private:
+  int64_t capture_time_ms_ = 0;
+};
+
+// Class to hold rtp packet with metadata for receiver side.
+class ReceivedRtpPacket : public rtp::Packet {
+ public:
+  explicit ReceivedRtpPacket(const ExtensionManager* extensions)
+      : Packet(extensions) {}
+
+  void GetHeader(RTPHeader* header) const;
+  // Time in local time base as close as it can to packet arrived on the
+  // network.
+  int64_t arrival_time_ms() const { return arrival_time_ms_; }
+  void set_arrival_time_ms(int64_t time) { arrival_time_ms_ = time; }
+
+  // Estimated from Timestamp() using rtcp Sender Reports.
+  NtpTime capture_ntp_time() const { return capture_time_; }
+  void set_capture_ntp_time(NtpTime time) { capture_time_ = time; }
+
+  // Flag if packet arrived via rtx.
+  bool retransmit() const { return retransmit_; }
+  void set_retransmit(bool value) { retransmit_ = value; }
+
+  int payload_type_frequency() const { return payload_type_frequency_; }
+  void set_payload_type_frequency(int value) {
+    payload_type_frequency_ = value;
+  }
+
+ private:
+  NtpTime capture_time_;
+  int64_t arrival_time_ms_ = 0;
+  int payload_type_frequency_ = 0;
+  bool retransmit_ = false;
+};
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_H_