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// Copyright 2019 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 "cast/streaming/sender_report_parser.h"
#include "cast/streaming/packet_util.h"
#include "util/logging.h"
namespace cast {
namespace streaming {
SenderReportParser::SenderReportWithId::SenderReportWithId() = default;
SenderReportParser::SenderReportWithId::~SenderReportWithId() = default;
SenderReportParser::SenderReportParser(RtcpSession* session)
: session_(session) {
OSP_DCHECK(session_);
}
SenderReportParser::~SenderReportParser() = default;
absl::optional<SenderReportParser::SenderReportWithId>
SenderReportParser::Parse(absl::Span<const uint8_t> buffer) {
absl::optional<SenderReportWithId> sender_report;
// The data contained in |buffer| can be a "compound packet," which means that
// it can be the concatenation of multiple RTCP packets. The loop here
// processes each one-by-one.
while (!buffer.empty()) {
const auto header = RtcpCommonHeader::Parse(buffer);
if (!header) {
return absl::nullopt;
}
buffer.remove_prefix(kRtcpCommonHeaderSize);
if (static_cast<int>(buffer.size()) < header->payload_size) {
return absl::nullopt;
}
auto chunk = buffer.subspan(0, header->payload_size);
buffer.remove_prefix(header->payload_size);
// Only process Sender Reports with a matching SSRC.
if (header->packet_type != RtcpPacketType::kSenderReport) {
continue;
}
if (header->payload_size < kRtcpSenderReportSize) {
return absl::nullopt;
}
if (ConsumeField<uint32_t>(&chunk) != session_->sender_ssrc()) {
continue;
}
SenderReportWithId& report = sender_report.emplace();
const NtpTimestamp ntp_timestamp = ConsumeField<uint64_t>(&chunk);
report.report_id = ToStatusReportId(ntp_timestamp);
report.reference_time =
session_->ntp_converter().ToLocalTime(ntp_timestamp);
report.rtp_timestamp =
last_parsed_rtp_timestamp_.Expand(ConsumeField<uint32_t>(&chunk));
report.send_packet_count = ConsumeField<uint32_t>(&chunk);
report.send_octet_count = ConsumeField<uint32_t>(&chunk);
report.report_block = RtcpReportBlock::ParseOne(
chunk, header->with.report_count, session_->receiver_ssrc());
}
// At this point, the packet is known to be well-formed. Cache the
// most-recently parsed RTP timestamp value for bit-expansion in future
// parses.
if (sender_report) {
last_parsed_rtp_timestamp_ = sender_report->rtp_timestamp;
}
return sender_report;
}
} // namespace streaming
} // namespace cast
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