Cast: Refactor RTCP handling

media/cast/net/rtcp/rtcp_builder.cc

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "media/cast/net/rtcp/rtcp_builder.h"
-
-#include <algorithm>
-#include <string>
-#include <vector>
-
-#include "base/big_endian.h"
-#include "base/logging.h"
-#include "media/cast/net/cast_transport_defines.h"
-#include "media/cast/net/pacing/paced_sender.h"
-
-namespace media {
-namespace cast {
-
-RtcpBuilder::RtcpBuilder(PacedSender* const outgoing_transport)
-    : transport_(outgoing_transport),
-      ssrc_(0) {
-}
-
-RtcpBuilder::~RtcpBuilder() {}
-
-void RtcpBuilder::SendRtcpFromRtpSender(
-    uint32 packet_type_flags,
-    const RtcpSenderInfo& sender_info,
-    const RtcpDlrrReportBlock& dlrr,
-    uint32 sending_ssrc,
-    const std::string& c_name) {
-  if (packet_type_flags & kRtcpRr ||
-      packet_type_flags & kRtcpPli ||
-      packet_type_flags & kRtcpRrtr ||
-      packet_type_flags & kRtcpCast ||
-      packet_type_flags & kRtcpReceiverLog ||
-      packet_type_flags & kRtcpRpsi ||
-      packet_type_flags & kRtcpRemb ||
-      packet_type_flags & kRtcpNack) {
-    NOTREACHED() << "Invalid argument";
-  }
-  ssrc_ = sending_ssrc;
-  c_name_ = c_name;
-  PacketRef packet(new base::RefCountedData<Packet>);
-  packet->data.reserve(kMaxIpPacketSize);
-  if (packet_type_flags & kRtcpSr) {
-    if (!BuildSR(sender_info, &packet->data)) return;
-    if (!BuildSdec(&packet->data)) return;
-  }
-  if (packet_type_flags & kRtcpBye) {
-    if (!BuildBye(&packet->data)) return;
-  }
-  if (packet_type_flags & kRtcpDlrr) {
-    if (!BuildDlrrRb(dlrr, &packet->data)) return;
-  }
-  if (packet->data.empty())
-    return;  // Sanity - don't send empty packets.
-
-  transport_->SendRtcpPacket(ssrc_, packet);
-}
-
-bool RtcpBuilder::BuildSR(const RtcpSenderInfo& sender_info,
-                          Packet* packet) const {
-  // Sender report.
-  size_t start_size = packet->size();
-  if (start_size + 52 > kMaxIpPacketSize) {
-    DLOG(FATAL) << "Not enough buffer space";
-    return false;
-  }
-
-  uint16 number_of_rows = 6;
-  packet->resize(start_size + 28);
-
-  base::BigEndianWriter big_endian_writer(
-      reinterpret_cast<char*>(&((*packet)[start_size])), 28);
-  big_endian_writer.WriteU8(0x80);
-  big_endian_writer.WriteU8(kPacketTypeSenderReport);
-  big_endian_writer.WriteU16(number_of_rows);
-  big_endian_writer.WriteU32(ssrc_);
-  big_endian_writer.WriteU32(sender_info.ntp_seconds);
-  big_endian_writer.WriteU32(sender_info.ntp_fraction);
-  big_endian_writer.WriteU32(sender_info.rtp_timestamp);
-  big_endian_writer.WriteU32(sender_info.send_packet_count);
-  big_endian_writer.WriteU32(static_cast<uint32>(sender_info.send_octet_count));
-  return true;
-}
-
-bool RtcpBuilder::BuildSdec(Packet* packet) const {
-  size_t start_size = packet->size();
-  if (start_size + 12 + c_name_.length() > kMaxIpPacketSize) {
-    DLOG(FATAL) << "Not enough buffer space";
-    return false;
-  }
-
-  // SDES Source Description.
-  packet->resize(start_size + 10);
-
-  base::BigEndianWriter big_endian_writer(
-      reinterpret_cast<char*>(&((*packet)[start_size])), 10);
-  // We always need to add one SDES CNAME.
-  big_endian_writer.WriteU8(0x80 + 1);
-  big_endian_writer.WriteU8(kPacketTypeSdes);
-
-  // Handle SDES length later on.
-  uint32 sdes_length_position = static_cast<uint32>(start_size) + 3;
-  big_endian_writer.WriteU16(0);
-  big_endian_writer.WriteU32(ssrc_);  // Add our own SSRC.
-  big_endian_writer.WriteU8(1);  // CNAME = 1
-  big_endian_writer.WriteU8(static_cast<uint8>(c_name_.length()));
-
-  size_t sdes_length = 10 + c_name_.length();
-  packet->insert(packet->end(), c_name_.c_str(),
-                 c_name_.c_str() + c_name_.length());
-
-  size_t padding = 0;
-
-  // We must have a zero field even if we have an even multiple of 4 bytes.
-  if ((packet->size() % 4) == 0) {
-    padding++;
-    packet->push_back(0);
-  }
-  while ((packet->size() % 4) != 0) {
-    padding++;
-    packet->push_back(0);
-  }
-  sdes_length += padding;
-
-  // In 32-bit words minus one and we don't count the header.
-  uint8 buffer_length = static_cast<uint8>((sdes_length / 4) - 1);
-  (*packet)[sdes_length_position] = buffer_length;
-  return true;
-}
-
-bool RtcpBuilder::BuildBye(Packet* packet) const {
-  size_t start_size = packet->size();
-  if (start_size + 8 > kMaxIpPacketSize) {
-    DLOG(FATAL) << "Not enough buffer space";
-    return false;
-  }
-
-  packet->resize(start_size + 8);
-
-  base::BigEndianWriter big_endian_writer(
-      reinterpret_cast<char*>(&((*packet)[start_size])), 8);
-  big_endian_writer.WriteU8(0x80 + 1);
-  big_endian_writer.WriteU8(kPacketTypeBye);
-  big_endian_writer.WriteU16(1);  // Length.
-  big_endian_writer.WriteU32(ssrc_);  // Add our own SSRC.
-  return true;
-}
-
-/*
-   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|reserved |   PT=XR=207   |             length            |
-  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-  |                              SSRC                             |
-  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-  |     BT=5      |   reserved    |         block length          |
-  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
-  |                 SSRC_1 (SSRC of first receiver)               | sub-
-  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block
-  |                         last RR (LRR)                         |   1
-  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-  |                   delay since last RR (DLRR)                  |
-  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
-*/
-bool RtcpBuilder::BuildDlrrRb(const RtcpDlrrReportBlock& dlrr,
-                              Packet* packet) const {
-  size_t start_size = packet->size();
-  if (start_size + 24 > kMaxIpPacketSize) {
-    DLOG(FATAL) << "Not enough buffer space";
-    return false;
-  }
-
-  packet->resize(start_size + 24);
-
-  base::BigEndianWriter big_endian_writer(
-      reinterpret_cast<char*>(&((*packet)[start_size])), 24);
-  big_endian_writer.WriteU8(0x80);
-  big_endian_writer.WriteU8(kPacketTypeXr);
-  big_endian_writer.WriteU16(5);  // Length.
-  big_endian_writer.WriteU32(ssrc_);  // Add our own SSRC.
-  big_endian_writer.WriteU8(5);  // Add block type.
-  big_endian_writer.WriteU8(0);  // Add reserved.
-  big_endian_writer.WriteU16(3);  // Block length.
-  big_endian_writer.WriteU32(ssrc_);  // Add the media (received RTP) SSRC.
-  big_endian_writer.WriteU32(dlrr.last_rr);
-  big_endian_writer.WriteU32(dlrr.delay_since_last_rr);
-  return true;
-}
-
-}  // namespace cast
-}  // namespace media