Date: 01 Aug 2001 04:50:11 -0500 From: Hal Snyder <hal@vailsys.com> To: <hackers@freebsd.org> Subject: Re: Finding MAC address of interface - programming question Message-ID: <873d7c9kj0.fsf@gamera.vail> In-Reply-To: <36F7B20351634E4FBFFE6C6A216B30D54C81@ecx1.edifecs.com> (Michael VanLoon's message of "Tue, 31 Jul 2001 16:34:17 -0700") References: <36F7B20351634E4FBFFE6C6A216B30D54C81@ecx1.edifecs.com>
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Michael VanLoon <MichaelV@EDIFECS.COM> writes:
> Thanks that's just exactly the information I was looking for. :-)
>
> I'm slow grunging through the code and man pages that take this apart.
>
> As far as UNPv1 I assume you're referring to Stevens' "Unix Network
> Programming"? If I'm not mistaken he doesn't go much below the
> socket level. A quick glance through didn't reveal anything of this
> nature.
See UNIX Network Programming 2ed, Vol.1, pp434-435 for SIOCGIFCONF
explanation. But nowadays getifaddrs(3) is easier:
/* hacked from netbsd ifconfig.c */
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
#include <stdio.h>
#include <net/if_dl.h>
int main (void) {
struct ifaddrs *ifap, *ifaphead;
int rtnerr;
const struct sockaddr_dl *sdl;
caddr_t ap;
int alen;
rtnerr = getifaddrs(&ifaphead);
if (rtnerr) {
perror(NULL);
return 1;
}
for (ifap = ifaphead; ifap; ifap = ifap->ifa_next) {
if (ifap->ifa_addr->sa_family == AF_LINK) {
sdl = (const struct sockaddr_dl *) ifap->ifa_addr;
ap = ((caddr_t)((sdl)->sdl_data + (sdl)->sdl_nlen));
alen = sdl->sdl_alen;
if (ap && alen > 0) {
int i;
printf ("%s:", ifap->ifa_name);
for (i = 0; i < alen; i++, ap++)
printf("%c%02x", i > 0 ? ':' : ' ', 0xff&*ap);
putchar('\n');
}
}
}
putchar('\n');
freeifaddrs(ifaphead);
return 0;
}
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