Re: socket api problem: can't bind an ipv6 socket to ::ffff:0.0.0.0

Hi David

Regardless of how we may feel about this thread, it did make me run
the BSD bindtest utility and look at the results.  What I found was
rather surprising.

There were multiple tests that one would exptect to succeed, but they
were failing.

Things that I consider broken:
  1) We can bind to a v4-mapped IPv6 address on a v6-only socket.
  2) We conflict IPv4 wildcrads with explicit IPv6 addresses and vice-versa
  3) We inconsitently treat V4 address and v4-mapped addresses.  As an example,
     try binging to 0.1.2.3. (This also kind of goes to binding
     ::ffff:0.0.0.0).

The following 4 RFC patches attempt to fix this.  I've run bindtest tool and
am currently analizing the results.  They look a heck of a lot better.

Thanks
-vlad