getaddrinfo()-related replication problem on FreeBSD

[Andriy Syrovenko]

2012/6/5 Ira Cooper <ira at samba.org>:
> On Mon, Jun 4, 2012 at 8:07 PM, Andrew Bartlett <abartlet at samba.org> wrote:
>> On Tue, 2012-06-05 at 02:12 +0300, Andriy Syrovenko wrote:
>>> Andrew,
>>>
>>> > A patch to the wscript to detect platforms with this breakage (I'm
>>> > surprised it hasn't been noticed elsewhere before!) and then a patch to
>>> > force the flag on seems most sensible at this point.
>>>
>>> The getaddrinfo() function on FreeBSD fails this way (i.e. returns
>>> EAI_FAIL) only when the following conditions are met:
>>>
>>> * The host name in question contains underscore.
>>> * The host name in question exists. If the name does not exists the
>>> function returns EAI_NONAME.
>>> * The host name in question is in the DNS. If it is placed in
>>> /etc/hosts the function succeeds.
>>>
>>> This makes basing detection of this kind of breakage on the analysis
>>> of the function's behavior particularly difficult. I don't see any
>>> other way to detect this kind of breakage except by checking for a
>>> particular OS name (and possibly version as well). Is this approach
>>> acceptable?
>>
>> It seems a very deliberate policy decision then.  I guess we may just
>> have to blacklist FreeBSD on this point then.
>>
>> The problem is that by not testing it (I can't see how we can, without
>> doing DNS lookups in configure, which would suck) we will never know how
>> far the rot spreads (what about the other BSDs?).
>
> Have you tried pinging the FreeBSD folks?  I can't believe they'd
> randomly break this.  If they did it intentionally, it'd be good to
> know why, in case we start seeing it elsewhere.

I haven't. I have tracked the issue in gdb and then looked into their
SVN repo though. The code that calls the host name checker from the
getaddrinfo() was added almost 12 years ago, and seems to be a part of
some IPv6-related work. The host name checker itself was imported from
the BIND.

The FreeBSD folks did make the rule checking less strict by allowing
the underscores in host names in Feb 2008
(http://svnweb.freebsd.org/base?view=revision&revision=176325) but
that change only allowed underscores in the middle of the name
component, i.e. 'host_name.net' is allowed, but '_host.net' and
'host_.net' are not. It looks strange and I concede it might have been
done unintentionally.

Andrey.