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/*
Perl ARP Extension
Lookup the MAC address of an ip address
Linux code
Programmed by Bastian Ballmann and Alexander Mueller
Last update: 20.09.2006
This program is free software; you can redistribute
it and/or modify it under the terms of the
GNU General Public License version 2 as published
by the Free Software Foundation.
This program is distributed in the hope that it will
be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
*/
#include <stdio.h>
#include <string.h>
#define _PATH_PROCNET_ARP "/proc/net/arp"
int arp_lookup_linux(char *dev, char *ip, char *mac)
{
FILE *fp;
char ipaddr[100];
char line[200];
char hwa[100];
char mask[100];
char device[100];
int num, type, flags;
if(strlen(mac) > 0)
strcpy(mac,"unknown");
else
return -1;
if(strlen(ip) == 0)
return -1;
if ((fp = fopen(_PATH_PROCNET_ARP, "r")) == NULL) {
perror(_PATH_PROCNET_ARP);
return (-1);
}
/* Bypass header -- read until newline */
if (fgets(line, sizeof(line), fp) != (char *) NULL)
{
/* Read the ARP cache entries. */
while (fgets(line, sizeof(line), fp))
{
num = sscanf(line, "%s 0x%x 0x%x %100s %100s %100s\n", ipaddr, &type, &flags, hwa, mask, device);
if (num < 4)
break;
if ((strlen(dev) == 0 || strcmp(dev, device) == 0) && strcmp(ip, ipaddr) == 0)
{
strcpy(mac, hwa);
break;
}
strcpy(mac, "unknown");
}
}
fclose(fp);
}
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