/************************************************************
 * File name	: Icmp.c									*
 * By 			: hugang, hgx2000@mail.china.com			*
 ************************************************************/

#include "armnet.h"
#include "..\inc\44blib.h"
#include <string.h>


extern NODE locnode;

/********************************************************************************************************
 * Return ICMP data length (-1 if no data), 0 if not ICMP												*
 ********************************************************************************************************/
short IsIcmp(IPKT *ip, short len)
{
    ICMPKT *icmp;
    unsigned short sum;
    short dlen = 0;

    if (ip->i.pcol==PICMP && len>=sizeof(ICMPHDR))
    {
        icmp = (ICMPKT *)ip;
        if ((sum=csum((unsigned char *)&icmp->c, (unsigned short)len)) == 0xffff)
        {
        	SwapIcmp(icmp);
            dlen = len>sizeof(ICMPHDR) ? len-sizeof(ICMPHDR) : -1;
        }
    }
    return(dlen);
}


/********************************************************************************************************
 * Make an ICMP packet 																					*
 ********************************************************************************************************/
short MakeIcmp(ETHERFRAME *efp, NODE *srcep, NODE *destp, unsigned char type, unsigned char codetype, unsigned short ident, unsigned short seq, unsigned short dlen)
{
    ICMPKT *icmp;
    unsigned short len;
    
    icmp = (ICMPKT *)(efp->edata);
    icmp->c.type = type;
    icmp->c.codetype = codetype;
    icmp->c.ident = ident;
    icmp->c.seq = seq;
    SwapIcmp(icmp);
    icmp->c.check = 0;
    len = (unsigned short)(dlen + sizeof(ICMPHDR));
    icmp->c.check = ~csum((unsigned char *)&icmp->c, len);
    
    return(MakeIp(efp, srcep, destp, PICMP, len));
}


/********************************************************************************************************
 * Swap byte order of ints in ICMP header 																*
 ********************************************************************************************************/
void SwapIcmp(ICMPKT *icmp)
{
    icmp->c.ident = swapw(icmp->c.ident);
    icmp->c.seq = swapw(icmp->c.seq);
}


/********************************************************************************************************
 * ICMP handler 																						*
 ********************************************************************************************************/
void  IcmpRcvPacket(ETHERFRAME *efp)
{
    ICMPKT *icmp;
	NODE   desnode;
    short txlen;

	icmp = (ICMPKT *)(efp->edata);
	if(icmp->c.type == ICREQ)
	{
		DEBUGF(ICMP_DEBUG,("Get ICMP ECHO_REQUEST\n"));
		if (READ_PACKED(icmp->i.dip) != locnode.ip) return;
		desnode.ip = READ_PACKED(icmp->i.sip);
		DEBUGF(ICMP_DEBUG, ("Finding ip %x in arp chache\n", desnode.ip));
		if(ArpFindCache(desnode.ip, desnode.mac))
		{
			DEBUGF(ARP_DEBUG, ("Fail to find ip %x in arp cache\n", desnode.ip));
			DEBUGF(ARP_DEBUG, ("Send Arp Request to ip %x\n",desnode.ip));
			ArpSendReq(efp, &desnode);
		}
		else
		{
     		txlen = MakeIcmp(efp, &locnode, &desnode, ICREP, 0, icmp->c.ident, icmp->c.seq, 0);
   			DEBUGF(ICMP_DEBUG,("Put ICMP ECHO_REPLY\n"));		
        	PutEthernet(efp, txlen);              /* Send packet */
		}
	}
}