#include "include/zipv4.h"#include "include/zicmp.h"#include "include/zudp.h"#include "include/ztcp.h"u16_t ip_id = 0;static u32_t chksum(void *dataptr, u16_t len){	u32_t acc;	for(acc = 0; len > 1; len -= 2) 	{		acc += *((u16_t *)dataptr)++;	}	/* add up any odd byte */	if(len == 1) 	{		acc += (u16_t)((*(u8_t *)dataptr) & 0xff) << 8;	}	return acc;}u16_t inet_chksum(void *dataptr, u16_t len){	u32_t acc;	acc = chksum(dataptr, len);	while(acc >> 16) 	{		acc = (acc & 0xffff) + (acc >> 16);	}		return ~(acc & 0xffff);}u16_t inet_chksum_pseudo(zbuffer_t *pbuf_dat, ipaddr_t *src, ipaddr_t *dest, u8_t proto, u16_t proto_len){	u32_t acc;  	zbuffer_t *q;  	u8_t swapped;  	acc = 0;  	swapped = 0; 	for(q = pbuf_dat; q != NULL; q = q->next)	{        	acc += chksum(q->pdata, q->len);    	while(acc >> 16)		{      		acc = (acc & 0xffff) + (acc >> 16);    	}    	if(q->len % 2 != 0)		{      		swapped = 1 - swapped;      		acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);    	}  	}  if(swapped)  {    acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);  }  acc += (*src & 0xffff);  acc += ((*src >> 16) & 0xffff);  acc += (*dest & 0xffff);  acc += ((*dest >> 16) & 0xffff);  acc += (u32_t)((u16_t)proto);  acc += (u32_t)(proto_len);      while(acc >> 16)   {    acc = (acc & 0xffff) + (acc >> 16);  }      return ~(acc & 0xffff);}	u8_t ip_input(znetif_t *pnetif, zbuffer_t *pbuffer){	ip_header_t	*pheader;	u8_t	hl;				pheader = (ip_header_t *)((u8_t *)pbuffer->pdata + ETH_HEAD_LEN);		/*step 1. check this is a ipv4 packet*/	if(IPH_V(pheader) != 4) 	{		zbuffer_delete(pbuffer);		return -1;	}	hl = IPH_HL(pheader);	/*step 2. the header is too long for our buffer*/	if(hl * 4 > pbuffer->len) 	{		zbuffer_delete(pbuffer);		return -1;	}		/*setp 3. we check IPV4 header checksum*/	if (inet_chksum(pheader, hl * 4) )	{		zbuffer_delete(pbuffer);		return -1;		}		/*setup 4. we only check DEST-ip is our ip's packet whithout brocast ip*/#if 0		if ( !((pheader->dest_ipaddr == pnetif->ipaddr) || 		   (ip_addr_isbroadcast(pheader->dest_ipaddr,pnetif->netmask) &&			ip_addr_maskcmp(pheader->dest_ipaddr,pnetif->ipaddr,pnetif->netmask) )))#else	if ( !(pheader->dest_ipaddr == pnetif->ipaddr) )#endif	{		zbuffer_delete(pbuffer);		return -1;	}	/*step 5. we only check none-fragment ip packet now FIXME*/		if(( IPH_OFFSET(pheader) & (IP_OFFMASK | IP_MF) ) != 0)	{		zbuffer_delete(pbuffer);			return -1;	}			/*setup 6.we check if length < pbuffer->totlen ) */		if ( pbuffer->tot_len > (IPH_LEN(pheader) + 14) )	{		pbuffer = zbuffer_adjust( pbuffer, 0, (-1)*(pbuffer->tot_len - (IPH_LEN(pheader) + 14)));		if ( pbuffer == NULL)			return -1;	}		/*step 7. we will check what type packet this is?*/	switch(IPH_PROTO(pheader))	{		case IP_PROTO_UDP:				udp_input(pnetif, pbuffer);				break;		case IP_PROTO_TCP:								tcp_input(pnetif, pbuffer);				break;		case IP_PROTO_ICMP:				return icmp_input(pnetif, pbuffer);				break;			default:				if ( !ip_addr_isbroadcast((pheader->dest_ipaddr), (pnetif->netmask)) && !ip_addr_ismulticast((pheader->dest_ipaddr)))				{					icmp_dest_unreach(pnetif,pbuffer, ICMP_DUR_PROTO);				}				else					zbuffer_delete(pbuffer);				return -1;				break;					}	return 0;}