The SIOCGIFADDR message generally happens when an application tries to
use SIOCGIFADDR on a BPF socket.  On some systems this works.  According
to Steve McCanne, it is not supposed to; you're supposed to use
SIOCGIFCONF instead.  I don't personally object to having some way to
query this information directly for a given device, but I do agree that
SIOCGIFADDR is *not* the way to do it; it's totally counter-intuitive to
override its normal meaning in this fashion.