Re: ioctl(sock, SIOCGIFHWADDR, &ifr) fails with 1.7

["Matthias Andree" <matthias dot andree at gmx dot de>]

Am 15.06.2009, 11:22 Uhr, schrieb FrÃdÃric Bron <frederic.bron@m4x.org>:

> > To fix your application, call either
> >
> > Âstruct ifconf ifc;
> > Âifc.ifc_len = sizeof (struct ifreq) * 32;
> > Âifc.ifc_buf = malloc (ifc.ifc_len);
> > Âif (ioctl (fd, SIOCGIFCONF, &ifc))
> > Â Â/* Resize ifc_buf and retry */
> > Âelse
> > Â Â{
> > Â Â Âstruct ifreq *ifr = ifc.ifc_req;
> > Â Â Âstruct ifreq ifr2;
> > Â Â Âfor (int i = 0; i < ifc.ifc_len; i += sizeof (struct ifreq), ++ifr)
> > Â Â Â Âif (!ioctl (fd, SIOCGIFADDR, &ifr2))
> > Â Â Â Â Â/* Print result for that interface */
> > Â Â}
>
> Thanks, this works half! No need of ifr2, ifr is enough.
> I saw the name change: 1.5 gives eth0, eth1, eth2, lo and 1.7 gives
> {821C54BE-...}...

Careful - this isn't portable to newer BSDs, as there ifc_len may exceed  
sizeof(struct ifreq).

getifaddrs() is probably the more portable solution here.

--
Matthias Andree

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