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

[Matthias Andree]

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

>> To fix your application, call either
>>
>> Â struct ifconf ifc;
>> Â ifc.ifc_len = sizeof (struct ifreq) * 32;
>> Â ifc.ifc_buf = malloc (ifc.ifc_len);
>> Â if (ioctl (fd, SIOCGIFCONF, &ifc))
>> Â  Â /* Resize ifc_buf and retry */
>> Â else
>> Â  Â {
>> Â  Â  Â struct ifreq *ifr = ifc.ifc_req;
>> Â  Â  Â struct ifreq ifr2;
>> Â  Â  Â for (int i = 0; i < ifc.ifc_len; i += sizeof (struct ifreq), ++ifr)
>> Â  Â  Â  Â if (!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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