*	\param buf pointer to data buffer (start of user data)
 *	\param blen buffer length in bytes (without space reserved at the 
 *		beginning of buffer for headers)
 *	\param dlen length of user data to be sent (in bytes)
 *	\return 
 *		\li -1 - Error (general error, e.g. parameters)
 *		\li -2 - ARP or lower layer not ready, try again later
 *		\li -3 - Socket closed or invalid local port
 *		\li >0 - OK (number represents number of bytes actually sent)
 *
 *	\warning
 *		\li <i>buf</i> parameter is a pointer to data to be sent in 
 *		user buffer. But note that there <b>MUST</b> be sufficient
 *		free buffer space before that data for UDP header (of #UDP_HLEN
 *		size). 
 *
 *	Use this function to send data over an already opened UDP socket. 
 */
INT16 udp_send (INT8 sochandle, UINT32 remip, UINT16 remport, UINT8* buf, UINT16 blen, UINT16 dlen)
{
	struct ucb* soc;
	UINT8* user_buf_start;
	UINT16 cs;
	UINT8 cs_cnt;
	INT16 i;
	
	if( sochandle > NO_OF_UDPSOCKETS ) {
		//UDP_DEBUGOUT("Socket handle non-valid\r\n");
		return(-1);
	}
	
	if( sochandle < 0 ) {
		//UDP_DEBUGOUT("Socket handle non-valid\r\n");
		return(-1);
	}
	
	if(remip == 0) {
		//UDP_DEBUGOUT("Remote IP 0 not allowed\r\n");
		return(-1);
	}
	
	if(remport == 0) {
		//UDP_DEBUGOUT("Remote port 0 not allowed\r\n");
		return(-1);
	}
	
	if( dlen > blen )
		dlen = blen;
	
	if( (dlen + UDP_HLEN) > UDP_SEND_MTU)
		dlen = UDP_SEND_MTU - UDP_HLEN;
	
	soc = &udp_socket[sochandle];		/* Get referense	*/

	if(soc->state != UDP_STATE_OPENED ) {
		//UDP_DEBUGOUT("UDP Socket Closed\r\n");
		return(-3);
	}
	
	if(soc->locport == 0) {
		//UDP_DEBUGOUT("ERROR:Socket local port is zero\r\n");
		return(-1);
	}

	user_buf_start = buf;
	
	buf -= UDP_HLEN;
	
	/* Put header	*/
	
	*buf++ = (UINT8)(soc->locport >> 8);
	*buf++ = (UINT8)soc->locport;
	*buf++ = (UINT8)(remport >> 8);
	*buf++ = (UINT8)remport;
	*buf++ = (UINT8)((dlen + UDP_HLEN) >> 8);
	*buf++ = (UINT8)(dlen + UDP_HLEN);
	*buf++ = 0;
	*buf = 0;
	
	buf = user_buf_start;
	buf -= UDP_HLEN;
	
	/* Calculate checksum if needed	*/
	
	cs = 0;
	
	if( soc->opts & UDP_OPT_SEND_CS) {
		cs = 0;
		cs_cnt = 0;
	
		/* Do it firstly to IP pseudo header	*/
		cs = ip_checksum(cs, (UINT8)(localmachine.localip >> 24), cs_cnt++);	
		cs = ip_checksum(cs, (UINT8)(localmachine.localip >> 16), cs_cnt++);
		cs = ip_checksum(cs, (UINT8)(localmachine.localip >> 8), cs_cnt++);
		cs = ip_checksum(cs, (UINT8)localmachine.localip, cs_cnt++);
	
		cs = ip_checksum(cs, (UINT8)(remip >> 24), cs_cnt++);	
		cs = ip_checksum(cs, (UINT8)(remip >> 16), cs_cnt++);
		cs = ip_checksum(cs, (UINT8)(remip >> 8), cs_cnt++);
		cs = ip_checksum(cs, (UINT8)remip, cs_cnt++);	
	
		cs = ip_checksum(cs, 0, cs_cnt++);
	
		cs = ip_checksum(cs, (UINT8)IP_UDP, cs_cnt++);
		
		cs = ip_checksum(cs, (UINT8)((dlen + UDP_HLEN) >> 8), cs_cnt++);
		cs = ip_checksum(cs, (UINT8)(dlen + UDP_HLEN), cs_cnt++);	
	
		/* Go to UDP header + data	*/
	
		buf = user_buf_start;
		buf -= UDP_HLEN;
	
		cs = (UINT16)(ip_checksum_buf(cs, buf, dlen + UDP_HLEN));
			
		cs = ~ cs;
	
		if(cs == 0)
			cs = 0xFFFF;
		/* Save checksum in correct place	*/
		buf = user_buf_start;
		buf -= UDP_HLEN;
		buf += 6;
		*buf++ = (UINT8)(cs >> 8);
		*buf = (UINT8)cs;	
		
		buf = user_buf_start;
		buf -= UDP_HLEN;
			
	}
	
	/* Send it to IP	*/
	
	//UDP_DEBUGOUT("Sending UDP...\r\n");
	
	i = process_ip_out(remip, IP_UDP, soc->tos, 100, buf, dlen + UDP_HLEN);
	
	/* Errors?	*/
	
	if( i < 0 )
		return(i);
	
	//UDP_DEBUGOUT("UDP packet sent\r\n");
	
	return(i - UDP_HLEN);


}



/** \brief Process received UDP frame
 *	\ingroup periodic_functions
 * 	\author 
 *		\li Jari Lahti (jari.lahti@violasystems.com)
 *	\date 15.07.2002
 *	\param frame pointer to received IP frame structure
 *	\param len length of data in bytes
 *	\return
 *		\li -1 - Error (packet not UDP, header errror or no socket for it)
 *		\li >0 - Packet OK
 *
 *	Invoke this function to process received UDP frames. See main_demo.c for
 *	an example on how to accomplish this.
 */
INT16 process_udp_in(struct ip_frame* frame, UINT16 len)
{
	struct ucb* soc;
	UINT16 checksum;
	UINT16 i;
	INT8 sochandle;
		
	/* Is this UDP?	*/
	
	//UDP_DEBUGOUT("Processing UDP...\n\r");
	
	if( frame->protocol != IP_UDP ) {
		//UDP_DEBUGOUT("ERROR: The protocol is not UDP\n\r");
		return(-1);
	}
	
	/* Start processing the message	*/
	
	NETWORK_RECEIVE_INITIALIZE(frame->buf_index);

	received_udp_packet.sport    = RECEIVE_NETWORK_W();
	received_udp_packet.dport    = RECEIVE_NETWORK_W();		
	received_udp_packet.tlen     = RECEIVE_NETWORK_W();	
	received_udp_packet.checksum = RECEIVE_NETWORK_W();
	
/* Commented out by R42485
	received_udp_packet.sport = ((UINT16)RECEIVE_NETWORK_B()) << 8;
	received_udp_packet.sport |= RECEIVE_NETWORK_B();
	
	received_udp_packet.dport = ((UINT16)RECEIVE_NETWORK_B()) << 8;
	received_udp_packet.dport |= RECEIVE_NETWORK_B();	
	
	received_udp_packet.tlen = ((UINT16)RECEIVE_NETWORK_B()) << 8;
	received_udp_packet.tlen |= RECEIVE_NETWORK_B();
	
	received_udp_packet.checksum = ((UINT16)RECEIVE_NETWORK_B()) << 8;
	received_udp_packet.checksum |= RECEIVE_NETWORK_B();
*/	

	if(received_udp_packet.tlen < UDP_HLEN ) {
		//UDP_DEBUGOUT("UDP frame too short\n\r");
		return(-1);
	}
	
	
	/* Map UDP socket	*/
	
	sochandle = -1;
	
	for( i=0; i < NO_OF_UDPSOCKETS; i++) {
		soc = &udp_socket[i];				/* Get referense	*/

		if(soc->state != UDP_STATE_OPENED )
			continue;
		
		if(soc->locport != received_udp_packet.dport)
			continue;
		
		/* Socket found	*/
		
		sochandle = (signed char)i;
		
		break;
	}
	
	if( sochandle < 0 ) {
		//UDP_DEBUGOUT("No socket found for received UDP Packet\r\n");
		
		/* TODO: Send ICMP	*/
		
		return(-1);
	}
	
	/* Calculate checksum for received packet	*/
	
	if(soc->opts & UDP_OPT_CHECK_CS) {
		if(received_udp_packet.checksum != 0) {
			checksum = 0;
			i = 0;
			
			/* Do it firstly to IP pseudo header	*/
			checksum = ip_checksum(checksum, (UINT8)(frame->dip >> 24), (UINT8)i++);	
			checksum = ip_checksum(checksum, (UINT8)(frame->dip >> 16), (UINT8)i++);
			checksum = ip_checksum(checksum, (UINT8)(frame->dip >> 8), (UINT8)i++);
			checksum = ip_checksum(checksum, (UINT8)frame->dip, (UINT8)i++);
	
			checksum = ip_checksum(checksum, (UINT8)(frame->sip >> 24), (UINT8)i++);	
			checksum = ip_checksum(checksum, (UINT8)(frame->sip >> 16), (UINT8)i++);
			checksum = ip_checksum(checksum, (UINT8)(frame->sip >> 8), (UINT8)i++);
			checksum = ip_checksum(checksum, (UINT8)frame->sip, (UINT8)i++);	
	
			checksum = ip_checksum(checksum, 0, (UINT8)i++);
	
			checksum = ip_checksum(checksum, (UINT8)IP_UDP, (UINT8)i++);
		
			checksum = ip_checksum(checksum, (UINT8)(len >> 8), (UINT8)i++);
			checksum = ip_checksum(checksum, (UINT8)len, (UINT8)i++);	
	
			NETWORK_RECEIVE_INITIALIZE(frame->buf_index);
	
			for(i=0; i < len; i++)
				checksum = ip_checksum(checksum, RECEIVE_NETWORK_B(), (UINT8)i);
	
			checksum = ~ checksum;
	
			if(checksum != IP_GOOD_CS) {
				//UDP_DEBUGOUT("ERROR: UDP Checksum failed!\n\r");
				return (-1);
			}
		
		}
	
		//UDP_DEBUGOUT("UDP Checksum OK\n\r");
	
	}
	
	
	received_udp_packet.buf_index = frame->buf_index + UDP_HLEN;
	NETWORK_RECEIVE_INITIALIZE(received_udp_packet.buf_index);
	
	/* Generate data event	*/
	
	(void)soc->event_listener(sochandle, UDP_EVENT_DATA, frame->sip, received_udp_packet.sport, received_udp_packet.buf_index, received_udp_packet.tlen - UDP_HLEN);
	
	return(1);

}

/** \brief Returns next free (not used) local port number
 * 	\author 
 *		\li Jari Lahti (jari.lahti@violasystems.com)
 *	\date 19.10.2002
 *	\return 
 *		\li 0 - no free ports!
 *		\li >0 - free local TCP port number
 *
 *	Function attempts to find new local port number that can be used to 
 *	establish a connection. 
 */
UINT16 udp_getfreeport (void){
	struct ucb* soc;
	static UINT16 lastport = 1;
	UINT16 start;
	UINT16 i;
	

	/* Try with every port to every socket untill free found	*/
		
	for( start = lastport++; start != lastport; lastport++)	{
		if(lastport == UDP_PORTS_END)
			lastport = 1;
			
		for(i = 0; i < NO_OF_UDPSOCKETS; i++) {
			soc = &udp_socket[i];					/* Get socket	*/
			
			if( (soc->state > UDP_STATE_CLOSED) && (soc->locport == lastport) )			{
				/* Blaah, this socket has reserved the port, go to next one	*/
				break; 
			}
			
		}	
			
		/* Did we found it?	*/
			
		if( i == NO_OF_UDPSOCKETS)
			break; 
			
	}
		
	if(lastport == start) {
		DEBUGOUT("Out of UDP ports!!\n\r");
		return(0);
	}
		
	return(lastport);
		
}