Date: Wed, 1 Aug 2001 11:51:52 +0400 From: Dmitry Diky <diwil@eis.ru> To: hackers@freebsd.org Subject: Re: Finding MAC address of interface - programming question Message-ID: <01080111515200.13229@wild.eis.ru> In-Reply-To: <3B67B425.40D6FE0E@webgiro.com> References: <36F7B20351634E4FBFFE6C6A216B30D54C80@ecx1.edifecs.com> <3B67B425.40D6FE0E@webgiro.com>
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the code as follows (at least it works in my case) :
#include <sys/types.h>
#include <sys/sysctl.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
/* IP */
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <arpa/inet.h>
#include <netdb.h>
/* OSI */
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#include <net/bpf.h>
#define NO_OF_IFS=092
char mac[NO_OF_IFS][6];
/* sdlr must be provided */
/* MAC will be filled */
/* number of IFs returned */
int get_ifs(struct sockaddr_dl *sdlr)
{
size_t=09=09needed;
/* prepare params for sysctl */
int=09=09=09mib[6] =3D { CTL_NET, PF_ROUTE, 0, 0, NET_RT_IFLIST, 0 };
char=09 =09=09*buf, *lim, *next;
struct if_msghdr=09*ifm, *nextifm;
struct ifa_msghdr=09*ifam;
struct sockaddr_dl=09*sdl;
int =09=09=09flags, addrcount=3D0, etheraddrcount=3D0;
char=09=09=09name[16]; /* cannot be more */
char=09=09=09*cp;
int=09=09=09n;
if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
perror("iflist-sysctl-estimate");
if ((buf =3D malloc(needed)) =3D=3D NULL) perror("malloc");
if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
perror("actual retrieval of interface table");
lim =3D buf + needed;
next =3D buf;
while (next < lim)
{
ifm =3D (struct if_msghdr *)next;
if (ifm->ifm_type =3D=3D RTM_IFINFO)
{
sdl =3D (struct sockaddr_dl *)(ifm + 1);
flags =3D ifm->ifm_flags;
}
else
{
exit (1);
}
next +=3D ifm->ifm_msglen;
ifam =3D NULL;
addrcount =3D 0;
while (next < lim)
{
nextifm =3D (struct if_msghdr *)next;
if (nextifm->ifm_type !=3D RTM_NEWADDR) break;
if (ifam =3D=3D NULL) ifam =3D (struct ifa_msghdr *)nextifm;
addrcount++;
next +=3D nextifm->ifm_msglen;
}
/*
* Ok, the interface is found
* Save it if it is an ethernet.
*/
if(sdl->sdl_type =3D=3D IFT_ETHER)
{
memcpy((void *)&sdlr[etheraddrcount],sdl, sizeof(struct sockaddr_dl=
));
etheraddrcount++;
strncpy(name, sdl->sdl_data, sdl->sdl_nlen);
name[sdl->sdl_nlen] =3D '\0';
cp =3D (char *)LLADDR(sdl);
if ((n =3D sdl->sdl_alen) > 0)
{
/*
if (sdl->sdl_type =3D=3D IFT_ETHER)
errMsg("\tEthernet %s:\tMAC - %s\n", name, macPrt(cp));
else
errMsg("\tlladdr %s:\tMAC - %s\n", name, macPrt(cp));
*/
memcpy(mac[etheraddrcount-1],cp,6);
}
}
}
if( etheraddrcount =3D=3D 0 ) printf("\tNone");
free(buf);
return etheraddrcount;
}
=08=A0=864=08
On Wednesday 01 August 2001 11:47, Andrzej Bialecki wrote:
> Michael VanLoon wrote:
> > > From: Chris Faulhaber [mailto:jedgar@fxp.org]
> > > Sent: Tuesday, July 31, 2001 3:56 PM
> > >
> > > On Tue, Jul 31, 2001 at 03:56:40PM -0700, Michael VanLoon wrote:
> > > > Please point me to a more appropriate forum if there is
> > >
> > > one. I'm kinda out
> > >
> > > > of my depth on this question. Pseudo code is fine. :-)
> > > >
> > > > What I'm looking for is how to enumerate the network
> > >
> > > interfaces and get the
> > >
> > > > Ethernet MAC address of one programmatically. Can anyone
> > >
> > > point me in the
> > >
> > > > right direction?
> > >
> > > /usr/src/sbin/ifconfig
> >
> > Thanks, I've already been looking at that. :-)
> >
> > The problem is, ifconfig does a lot of other stuff, and it's very poo=
rly
> > documented.
> >
> > I was hoping someone could give me some hints to speed my research. =
Such
> > as recommended places to look in the code, ioctl's used and/or sysctl=
's
> > called.
> >
> > I'm happy to do most of the work myself, I'm just asking for some hin=
ts.
> > :-) Much appreciated.
>
> Take a look at /usr/src/release/picobsd/tinyware/ns. I went through the
> same hoops some time ago... :-)
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