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PCICMP.C
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1997-03-08
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8KB
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249 lines
#include <copyright.h>
#include <wattcp.h>
#include <mem.h>
#include <dos.h>
/*
* ICMP - RFC 792
*/
static char *unreach[] = {
"Network Unreachable",
"Host Unreachable",
"Protocol Unreachable",
"Port Unreachable",
"Fragmentation needed and DF set",
"Source Route Failed" };
static char *exceed[] = {
"TTL exceeded in transit",
"Frag ReAsm time exceeded" };
static char *redirect[] = {
"Redirect for Network",
"Redirect for Host",
"Redirect for TOS and Network",
"Redirect for TOS and Host" };
/* constants */
#include <icmp.h>
static word icmp_id = 0;
static longword ping_hcache = 0; /* host */
static longword ping_tcache = 0; /* time */
static longword ping_number = 0;
extern word multihomes;
/* handler called in icmp_handler if this isn't null */
static icmp_handler_type user_icmp_handler = NULL;
longword _chk_ping( longword host, longword *ptr )
{
if ( ping_hcache == host ) {
ping_hcache = 0xffffffffL;
*ptr = ping_number;
return( ping_tcache );
}
return( 0xffffffffL );
}
static void icmp_print( icmp_pkt *icmp, char *msg )
{
icmp=icmp; // get rid of warning
outs("\n\rICMP: ");
outs( msg );
outs("\n\r");
}
/*
*
*/
static struct _pkt *icmp_Format( longword destip )
{
eth_address dest;
/* char *temp; */
/* we use arp rather than supplied hardware address */
/* after first ping this will still be in cache */
if ( !_arp_resolve( destip , &dest, 0 ))
return( NULL ); /* unable to find address */
return( (struct _pkt*)_eth_formatpacket( &dest, 8 )); /* &dest okay? */
}
/*
* icmp_Reply - format and send a reply packet
* - note that src and dest are NETWORK order not host!!!!
*/
static void icmp_Reply( struct _pkt *p, longword src, longword dest, int icmp_length )
{
in_Header *ip;
icmp_pkt *icmp;
ip = &p->in;
memset( ip, 0, sizeof( in_Header ));
icmp = &p->icmp;
/* finish the icmp checksum portion */
icmp->unused.checksum = 0;
icmp->unused.checksum = ~checksum( icmp, icmp_length );
/* encapsulate into a nice ip packet */
ip->ver = 4;
ip->hdrlen = 5;
ip->length = intel16( sizeof( in_Header ) + icmp_length);
ip->tos = 0;
ip->identification = intel16( icmp_id ++); /* not using ip id */
// ip->frag = 0;
ip->ttl = 250;
ip->proto = ICMP_PROTO;
ip->checksum = 0;
ip->source = src;
ip->destination = dest;
ip->checksum = ~ checksum( ip, sizeof( in_Header ));
_eth_send( intel16( ip->length ));
}
/*
* Register the user ICMP handler. Only one at a time...
* To disable user handler, call set_icmp_handler(NULL);
*/
void set_icmp_handler( icmp_handler_type user_handler )
{
_disable();
user_icmp_handler = user_handler;
_enable();
}
int icmp_handler( in_Header *ip )
{
icmp_pkt *icmp, *newicmp;
struct _pkt *pkt;
int len, code;
in_Header *ret;
len = in_GetHdrlenBytes( ip );
icmp = (icmp_pkt*)((byte *)ip + len);
len = intel16( ip->length ) - len;
if ( checksum( icmp, len ) != 0xffff ) {
outs("ICMP received with bad checksum\n\r");
return( 1 );
}
/*
* If there's a user handler installed, call the user's handler;
* return of anything but 0 and this handler will continue
* processing the message after the user is done with it.
* Otherwise, stop processing it now.
*/
if( user_icmp_handler )
{
if( (user_icmp_handler)( ip ) == 0 ) /* don't continue processing? */
return( 1 );
}
code = icmp->unused.code;
ret = & (icmp->ip.ip);
switch ( icmp->unused.type) {
case 0 : /* icmp echo reply received */
/* icmp_print( icmp, "received icmp echo receipt"); */
/* check if we were waiting for it */
ping_hcache = intel( ip->source );
ping_tcache = set_timeout( 1 ) - *(longword *)(&icmp->echo.identifier );
if (ping_tcache > 0xffffffffL)
ping_tcache += 0x1800b0L;
ping_number = *(longword*)( ((byte*)(&icmp->echo.identifier)) + 4 );
/* do more */
break;
case 3 : /* destination unreachable message */
if (code < 6) {
icmp_print( icmp, unreach[ code ]);
/* handle udp or tcp socket */
if (ret->proto == TCP_PROTO)
_tcp_cancel( ret, 1, unreach[ code ], 0 );
if (ret->proto == UDP_PROTO)
_udp_cancel( ret );
}
break;
case 4 : /* source quench */
if (ret->proto == TCP_PROTO)
_tcp_cancel( ret, 2, NULL, 0 );
break;
case 5 : /* redirect */
if (code < 4) {
if (ret->proto == TCP_PROTO)
/* do it to some socket guy */
_tcp_cancel( ret, 5, NULL, icmp->ip.ipaddr );
}
break;
case 8 : /* icmp echo request */
/* icmp_print( icmp, "PING requested of us"); */
// don't reply if the request was made by ourselves
// such as a problem with Etherslip pktdrvr
if ( (longword) (ip->destination - intel( my_ip_addr)) > multihomes )
return( 1 );
// do arp and create packet
/* format the packet with the request's hardware address */
pkt = (struct _pkt*)(_eth_formatpacket( _eth_hardware((byte*)ip), 8));
newicmp = &pkt->icmp;
movmem( icmp, newicmp, len );
newicmp->echo.type = 0;
newicmp->echo.code = code;
/* use supplied ip values in case we ever multi-home */
/* note that ip values are still in network order */
icmp_Reply( pkt,ip->destination, ip->source, len );
/* icmp_print( newicmp, "PING reply sent"); */
break;
case 11 : /* time exceeded message */
if (code < 2 ) {
icmp_print( icmp, exceed[ code ]);
if ((ret->proto == TCP_PROTO) && (code != 1))
_tcp_cancel( ret, 1, NULL, 0 );
}
break;
case 12 : /* parameter problem message */
icmp_print( icmp, "IP Parameter problem");
break;
case 13 : /* timestamp message */
icmp_print( icmp, "Timestamp message");
/* send reply */
break;
case 14 : /* timestamp reply */
icmp_print( icmp, "Timestamp reply");
/* should store */
break;
case 15 : /* info request */
icmp_print( icmp,"Info requested");
/* send reply */
break;
case 16 : /* info reply */
icmp_print( icmp,"Info reply");
break;
}
return( 1 );
}