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#include <u.h>
#include <libc.h>
#include <ip.h>
#include "../icmp.h"
static void
catch(void *a, char *msg)
{
USED(a);
if(strstr(msg, "alarm"))
noted(NCONT);
else
noted(NDFLT);
}
#define MSG "dhcp probe"
/*
* make sure noone is using the address
* TODO: ipv6 ping
*/
int
icmpecho(uchar *a)
{
int fd, i, n, len, rv;
ushort sseq, x;
char buf[512];
Icmphdr *ip;
rv = 0;
if (!isv4(a))
return 0;
sprint(buf, "%I", a);
fd = dial(netmkaddr(buf, "icmp", "1"), 0, 0, 0);
if(fd < 0){
return 0;
}
sseq = getpid()*time(0);
ip = (Icmphdr *)(buf + IPV4HDR_LEN);
notify(catch);
for(i = 0; i < 3; i++){
ip->type = EchoRequest;
ip->code = 0;
strcpy((char*)ip->data, MSG);
ip->seq[0] = sseq;
ip->seq[1] = sseq>>8;
len = IPV4HDR_LEN + ICMP_HDRSIZE + sizeof(MSG);
/* send a request */
if(write(fd, buf, len) < len)
break;
/* wait 1/10th second for a reply and try again */
alarm(100);
n = read(fd, buf, sizeof(buf));
alarm(0);
if(n <= 0)
continue;
/* an answer to our echo request? */
x = (ip->seq[1]<<8) | ip->seq[0];
if(n >= len && ip->type == EchoReply && x == sseq &&
strcmp((char*)ip->data, MSG) == 0){
rv = 1;
break;
}
}
close(fd);
return rv;
}
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