// RTPPacket.cpp: implementation of the RTPPacket class.
//
//////////////////////////////////////////////////////////////////////

#include "RTPPacket.h"
#include "Exception.h"
#include "TraceUser.h"

RTPPacket *
RTPPacket::CreateRTPPacket(char *buffer, int len, Tracer *tracer)
{
	int returnCode = 0;
	RTPPacket *rtpPacket = NULL;

	// make a copy of the class variables so that we can fill them in to test
	// for the validity of the packet before we create the RTPPacket structure
	bool			headerExtension;
	unsigned char	contributorCount;
	bool			marker;
	unsigned char	payloadType;
	unsigned short	seqNo;
	unsigned long	timestamp;
	unsigned long	ssrc;
	unsigned long	dataLen;
	char			*rtpData;
	unsigned char	version;
	unsigned long	headerLength;

	char			*packetPtr;
	unsigned long	totalLength;
	unsigned long	numPadding;

	try
	{
		if (len < 12)
		{
			throw Exception(-10, "invalid RTP packet : len = %d bytes", len);
		}
		packetPtr			= buffer;
		totalLength			= len;
		numPadding			= packetPtr[0] & 0x20 ? packetPtr[totalLength - 1] : 0;

		headerExtension		= (packetPtr[0] & 0x10) != 0;
		if (headerExtension)
		{
			throw Exception(-20, "header extension not supported");
		}

		contributorCount	= packetPtr[0] & 0x0f;
		marker				= (packetPtr[1] & 0x80) != 0;
		payloadType			= packetPtr[1] & 0x7f;
		seqNo				= ntohs(*((short *)(packetPtr + 2)));
		timestamp			= ntohl(*((unsigned long *)(packetPtr + 4)));
		ssrc				= ntohl(*((unsigned long *)(packetPtr + 8)));

		version				= (packetPtr[0] & 0xc0) >> 6;
		if (version != 2)
		{
			throw Exception(-30, "invalid RTP version %d", version);
		}

		headerLength		= 12 + 4 * contributorCount;
		if (totalLength < headerLength)
		{
			throw Exception(-40, "totalLength (%d) < headerLength (%d) ! contributor count = %d", totalLength, headerLength, contributorCount);
		}

		if (totalLength < (headerLength + numPadding))
		{
			throw Exception(-50, "totalLength (%d) < headerLength (%d) + numPadding (%d)", totalLength, headerLength, numPadding);
		}
		dataLen				= totalLength - headerLength - numPadding;
		rtpData				= packetPtr + headerLength;

		// now that all checks have been made, we will create and return the RTP packet
		rtpPacket = new RTPPacket(buffer, len);
	}
	catch (Exception exception)
	{
		tracer->tracef(ERR, "RTPPacket::CreateRTPPacket : error %d : %s\n", exception.ErrorCode(), exception.ErrorMessage());
		if (rtpPacket)
		{
			delete rtpPacket;
		}
		rtpPacket = NULL;
	}
	return rtpPacket;
}

RTPPacket *
RTPPacket::CloneHeader()
{
	RTPPacket *newHeader = new RTPPacket(this->packetPtr, this->headerLength);
	if (newHeader)
	{
		newHeader->packetPtr = NULL;
		newHeader->rtpData = NULL;
	}
	return newHeader;
}