Comment 14 for bug 1492621

Currently with glibc-2.15-51.fc17.x86_64 I can reproduce it with:

  hints.ai_family = AF_INET6;
  hints.ai_flags = AI_ADDRCONFIG; // and optional AI_V4MAPPED

I can no longer reproduce with SSH (possibly because of some updates
that affect SSH's networking, i don't know).

My feeling is that we should *never* discard literal IP adresses
based on AI_ADDRCONFIG. At least not unless we check against
*family* together with *scope* but even then it's very doubtful
to go directly against user's input.

As for names like 'localhost', 'localhost4' and various names you can
use for node-local and link-local addresses, I'm strictly against trying
to enumerate them as you cannot guess all possible names. Would
you for example check the suffix ".local" and treat the result as a
link-local FQDN? But it may be a global address also.

I actually don't believe in any checks that work with the name and
not the address. When you have the address, you can check it against
several rules to guess (and usually know) the scope.