OpenBSD 4.4 gnutls-serv IPv6 Only Bug

[Peter Hendrickson]

> > Yes, but it's somewhat complicated, you have to create a socket for each 
> > returned addrinfo structure, bind them all, set them non-blocking, and 
> > then poll across them to wait for a connection, and cope with the edge 
> > cases with v6-mapped IPv4 addresses which make it not that simple.
> 
> I tried to implement that:
> 
> http://git.savannah.gnu.org/cgit/gnutls.git/commit/?id=6ccb2ccaf7d0e8a5391433a6654eef08059f686c
> 
> Peter, can you test the latest daily snapshot?
> http://daily.josefsson.org/gnutls/gnutls-20090424.tar.gz

I tested the 20090424 snapshot under OpenBSD 4.4 and gnutls-serv emits
a bind error for the IPv4 socket and only listens on the IPv6 socket.

When bind() is called in listen_socket(), it is given two "res->"
arguments, but it should be two "ptr->" arguments.  Otherwise it
doesn't move to ptr->ai_next the second time through the for loop.

Like this:
> diff serv.c.orig serv.c
> 685c685
> <       if (bind (s, res->ai_addr, res->ai_addrlen) < 0)
> ---
> >       if (bind (s, ptr->ai_addr, ptr->ai_addrlen) < 0)

And I suspect this problem has the same cause:
> There seems to be a cosmetic problem, though, on my normal debian
> machine:
> 
> jas at mocca:~/src/gnutls/src master$ ./gnutls-serv 
> Set static Diffie Hellman parameters, consider --dhparams.
> Echo Server listening to 0.0.0.0:5556 (family 2)...done
> Echo Server listening to :::5556 (family 10)...bind() failed: Invalid argument
> ^CExiting via signal 2
> jas at mocca:~/src/gnutls/src master$ 
>
> It seems bind fail on my IPv6 interface, which is probably right because
> I haven't setup IPv6 here.  Is ignoring bind failures the right thing?
> I'm not sure why getaddrinfo returns the IPv6 interface at all.

My guess is that you actually have an IPv6 address assigned to an
interface.  It's probably a "link-local" default address, but an
address nontheless.  It is proper that getaddrinfo returns an entry
for it -- and when it does you get hit by the bad call to bind().

Peter