ip.c

tcp内存管理常用函数,用好的话对程序结构有很大的帮助!谢谢!

		return(-2);
		
	/* Select network buffer						*/
	/* TODO: This network related stuff should 		*/
	/* be moved and abstracted to Ethernet layer	*/
	
	switch(pcol) {
	
		case IP_ICMP:
		
			NETWORK_SEND_INITIALIZE(ICMP_BUF);
			IP_DEBUGOUT("Assembling IP packet to ICMP buffer\n\r");
			
			break;
			
		case IP_UDP:
		
			NETWORK_SEND_INITIALIZE(UDP_BUF);
			IP_DEBUGOUT("Assembling IP packet to UDP buffer\n\r");
		
			break;
			
		case IP_TCP:
		
			NETWORK_SEND_INITIALIZE(TCP_BUF);
			IP_DEBUGOUT("Assembling IP packet to TCP buffer\n\r");
			
			break;
	
		default:			/* Unknown protocol	*/
			return(-1);
	}
	
	/* Fill the Ethernet information	*/
	
	for( i=0; i<MAXHWALEN; i++)	{
		send_frame.destination[i] = qstruct->hwadr[i];
		send_frame.source[i] = localmachine.localHW[i];
	}
	
	send_frame.protocol = PROTOCOL_IP;
	
#pragma MESSAGE DISABLE C1825		//Warning: indirection
	NETWORK_ADD_DATALINK(&send_frame);
#pragma MESSAGE WARNING C1825		//Warning: indirection       
	
	/* Construct the IP header	*/	
	send_ip_packet.vihl     = IP_DEF_VIHL;
	send_ip_packet.tos      = tos;
	send_ip_packet.tlen     = IP_HLEN + len;
	send_ip_packet.id       = ip_id++;
	send_ip_packet.frags    = 0;
	send_ip_packet.ttl      = ttl;
	send_ip_packet.protocol = pcol;
	send_ip_packet.checksum = 0;
	send_ip_packet.sip      = localmachine.localip;
	send_ip_packet.dip      = ipadr;
	
	/* Calculate checksum for the IP header	*/	
	send_ip_packet.checksum = (UINT16)(ip_construct_cs( &send_ip_packet ));	

	/* Assemble bytes to network	*/	
	SEND_NETWORK_B(send_ip_packet.vihl);
	SEND_NETWORK_B(send_ip_packet.tos);
	SEND_NETWORK_W( send_ip_packet.tlen );
	SEND_NETWORK_W( send_ip_packet.id );
	SEND_NETWORK_W( send_ip_packet.frags );
	SEND_NETWORK_B(send_ip_packet.ttl);
	SEND_NETWORK_B(send_ip_packet.protocol);	
	SEND_NETWORK_W( send_ip_packet.checksum );

	SEND_NETWORK_B( (UINT8)(send_ip_packet.sip >> 24) );
	SEND_NETWORK_B( (UINT8)(send_ip_packet.sip >> 16) );
	SEND_NETWORK_B( (UINT8)(send_ip_packet.sip >> 8) );
	SEND_NETWORK_B( (UINT8) send_ip_packet.sip );
	SEND_NETWORK_B( (UINT8)(send_ip_packet.dip >> 24) );
	SEND_NETWORK_B( (UINT8)(send_ip_packet.dip >> 16) );
	SEND_NETWORK_B( (UINT8)(send_ip_packet.dip >> 8) );
	SEND_NETWORK_B( (UINT8) send_ip_packet.dip );
	
	/* Assemble data	*/	
	SEND_NETWORK_BUF(dat,len);
		
	/* Launch it		*/	
	NETWORK_COMPLETE_SEND( send_ip_packet.tlen );
	
	return(len);	
}

/** \brief Construct checksum of the IP header
 * 	\author 
 *		\li Jari Lahti
 *	\date 08.07.2002
 *	\param frame pointer to ip_frame structure holding header information
 *		based on which checksum is calculated
 *	\return Calculated checksum
 *
 *	Checksum of the supplied IP datagram is calculated.
 *
 */
UINT32 ip_construct_cs (struct ip_frame* frame)
{
	UINT16 ip_cs;
	UINT8 cs_cnt;
	UINT8 olen;
	UINT8 i;
	
	ip_cs = 0;
	cs_cnt = 0;
	
	ip_cs = ip_checksum(ip_cs, frame->vihl, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, frame->tos, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->tlen >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->tlen, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->id >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->id, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->frags >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->frags, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, frame->ttl, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, frame->protocol, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->sip >> 24), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->sip >> 16), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->sip >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->sip, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->dip >> 24), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->dip >> 16), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->dip >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->dip, cs_cnt++);	
	
	/* Is there options?				*/
		
	olen = ((frame->vihl & 0x0F) << 2) - IP_MIN_HLEN;
	
	for( i=0; i<olen; i++)
		ip_cs = ip_checksum(ip_cs, (UINT8)frame->opt[i], cs_cnt++);
	
	/* Take complement	*/
	
	ip_cs = ~ ip_cs;

	return(ip_cs);

}

/** \brief Check IP frame's checksum
 * 	\author 
 *		\li Jari Lahti
 *	\date 11.06.2002
 *	\param frame pointer to IP frame to be checked
 *	\return
 *		\li 0 - checksum corrupted
 *		\li 1 - checksum OK
 *
 *	Checksum of an IP packet is calculated and compared with the received
 *	checksum. Error is signaled if there is discrepancy between them.
 *
 */
UINT8 ip_check_cs (struct ip_frame* frame)
{
	UINT16 ip_cs;
	UINT8 cs_cnt;
	UINT8 olen;
	UINT8 i;
	
	ip_cs = 0;
	cs_cnt = 0;
	
	ip_cs = ip_checksum(ip_cs, frame->vihl, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, frame->tos, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->tlen >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->tlen, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->id >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->id, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->frags >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->frags, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, frame->ttl, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, frame->protocol, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->checksum >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->checksum, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->sip >> 24), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->sip >> 16), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->sip >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->sip, cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->dip >> 24), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->dip >> 16), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)(frame->dip >> 8), cs_cnt++);
	ip_cs = ip_checksum(ip_cs, (UINT8)frame->dip, cs_cnt++);	
	
	/* Is there options?				*/
		
	olen = ((frame->vihl & 0x0F) << 2) - IP_MIN_HLEN;
	
	for( i=0; i<olen; i++)
		ip_cs = ip_checksum(ip_cs, (UINT8)frame->opt[i], cs_cnt++);
	
	/* Analyze the result	*/
	
	ip_cs = ~ ip_cs;
	
	if(ip_cs == IP_GOOD_CS)
		return 1;
	
	/* BEEEEEEP, it failed!	*/
	
	return 0;
	

}

/** \brief Used for constructuing IP checksum
 * 	\author 
 *		\li Jari Lahti
 *	\date 24.02.2002
 *	\param cs last checksum value
 *	\param dat byte to be added to checksum
 *	\param count byte indicating whether dat is MSB or LSB byte
 *	\return new checksum value
 *
 *	Based on count value, dat byte is added to checksum either as a MSB
 *	or a LSB byte and the new checksum value is then returned.
 *
 */
UINT16 ip_checksum (UINT16 cs, UINT8 dat, UINT8 count)
{
	UINT8 b = dat;
	UINT8 cs_l;
	UINT8 cs_h;
	
	cs_h = (UINT8)(cs >> 8); 
	cs_l = (UINT8)cs;

	if( count & 0x01 ) {
		/* We are processing LSB	*/
		
		if( (cs_l = cs_l + b) < b ) 
		{
			if( ++cs_h == 0 )
				cs_l++;
		}
		
	} else 
	{
		/* We are processing MSB	*/
		
		if( (cs_h = cs_h + b) < b )	
		{
			if( ++cs_l == 0 )
				cs_h++;
		}
	}

	return( ( (UINT16)cs_h << 8 ) + cs_l);
}


/** \brief Used for constructuing IP checksum of a data buffer
 * 	\author 
 *		\li Jari Lahti
 *	\date 03.08.2003
 *	\param cs last checksum value
 *	\param buf buffer who's checksum we're calculating
 *	\param len length of data in buffer
 *	\return new checksum value
 *
 *	Calculates checksum of the data in buffer and returns new
 *	checksum value.
 */
UINT32 ip_checksum_buf (UINT16 cs, UINT8* buf, UINT16 len)
{
	UINT16 dat;
	UINT32 temp;
	
	temp = cs;
	
	while(len>1)
	{
		len -= 2;
		dat = *buf++;
		dat <<= 8;
		dat |= *buf++;
		temp += dat;
	}
	
	temp = (temp >> 16) + (temp & 0xFFFF);	/* Add in carry		*/
	temp += (temp >>16);					/* Maybe one more	*/
	
	if(len)
		temp = (UINT32)(ip_checksum((UINT16)(temp), *buf, 0));
	
	return((UINT16)temp);

}