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#include <u.h>
#include <libc.h>
#include <ip.h>
typedef struct Icmp Icmp;
struct Icmp
{
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
uchar ttl; /* Time to live */
uchar proto; /* Protocol */
uchar ipcksum[2]; /* Header checksum */
uchar src[4]; /* Ip source */
uchar dst[4]; /* Ip destination */
uchar type;
uchar code;
uchar cksum[2];
uchar icmpid[2];
uchar seq[2];
uchar data[1];
};
enum
{ /* Packet Types */
EchoReply = 0,
Unreachable = 3,
SrcQuench = 4,
EchoRequest = 8,
TimeExceed = 11,
Timestamp = 13,
TimestampReply = 14,
InfoRequest = 15,
InfoReply = 16,
ICMP_IPSIZE = 20,
ICMP_HDRSIZE = 8
};
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
*/
int
icmpecho(uchar *a)
{
int fd;
char buf[512];
Icmp *ip;
int i, n, len;
ushort sseq, x;
int rv;
return 0;
rv = 0;
sprint(buf, "%I", a);
fd = dial(netmkaddr(buf, "icmp", "1"), 0, 0, 0);
if(fd < 0){
return 0;
}
sseq = getpid()*time(0);
ip = (Icmp*)buf;
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 = ICMP_IPSIZE+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)
if(ip->type == EchoReply)
if(x == sseq)
if(strcmp((char*)ip->data, MSG) == 0){
rv = 1;
break;
}
}
close(fd);
return rv;
}
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