libdatachannel/src/plihandler.cpp

/**
 * Copyright (c) 2023 Arda Cinar
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include "plihandler.hpp"
#include "rtp.hpp"

#if RTC_ENABLE_MEDIA

namespace rtc {

PliHandler::PliHandler(std::function<void(void)> onPli) : mOnPli(onPli) {}

void PliHandler::incoming(message_vector &messages, [[maybe_unused]] const message_callback &send) {
	for (const auto &message : messages) {
		size_t offset = 0;
		while ((sizeof(RtcpHeader) + offset) <= message->size()) {
			auto header = reinterpret_cast<RtcpHeader *>(message->data() + offset);
			uint8_t payload_type = header->payloadType();

			if (payload_type == 196) {
				// FIR message, call pli handler anyway
				mOnPli();
				break;
			} else if (payload_type == 206) {
				// On a payload specific fb message, there is a "feedback message type" (FMT) in the
				// header instead of a report count. PT = 206, FMT = 1 means a PLI message
				uint8_t feedback_message_type = header->reportCount();
				if (feedback_message_type == 1) {
					mOnPli();
					break;
				}
			}
			offset += header->lengthInBytes();
		}
	}
}

} // namespace rtc

#endif // RTC_ENABLE_MEDIA