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/*
Perl ARP Extension
Lookup the MAC address of an ip address
BSD code
Programmed by Bastian Ballmann
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 <sys/file.h>
#include <sys/socket.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/if_arp.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <arpa/inet.h>
#include <sys/sysctl.h>
#define ROUNDUP(a) \
((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
int arp_lookup_bsd(u_char *dev, u_char *ip, char *mac)
{
int mib[6];
size_t needed;
char *lim, *buf, *next;
if(strlen(mac) > 0)
strcpy(mac,"unknown");
else
return -1;
if(strlen(ip) == 0)
return -1;
strcpy(mac,"unknown");
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
mib[5] = RTF_LLINFO;
/* Retrieve routing table */
if(sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
{
perror("route-sysctl-estimate");
exit(1);
}
if((buf = malloc(needed)) == NULL)
{
perror("malloc");
exit(1);
}
if(sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
{
perror("retrieval of routing table");
exit(1);
}
lim = buf + needed;
next = buf;
/* Search for the requested ip */
while (next < lim)
{
struct rt_msghdr *rtm = (struct rt_msghdr *)next;
struct sockaddr_inarp *sinarp = (struct sockaddr_inarp *)(rtm + 1);
struct sockaddr_dl *sdl = (struct sockaddr_dl *)((char *)sinarp + ROUNDUP(sinarp->sin_len));
if( (sdl->sdl_alen) && (!strcmp(ip,inet_ntoa(sinarp->sin_addr))) )
{
sprintf(mac,"%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
}
next += rtm->rtm_msglen;
}
free(buf);
return(0);
}
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