[122221] in North American Network Operators' Group
Re: Regular Expression for IPv6 addresses
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Tue Feb 9 17:27:25 2010
To: Mark Andrews <marka@isc.org>
In-Reply-To: Your message of "Wed, 10 Feb 2010 09:12:11 +1100."
<201002092212.o19MCBxG063598@drugs.dv.isc.org>
From: Valdis.Kletnieks@vt.edu
Date: Tue, 09 Feb 2010 17:25:28 -0500
Cc: nanog@nanog.org, "Richard E. Brown" <Richard.E.Brown@dartware.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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On Wed, 10 Feb 2010 09:12:11 +1100, Mark Andrews said:
> In message <alpine.DEB.1.10.1002091548170.25663@red.crap.retrofitta.se>, Thomas
> Habets writes:
> > On Fri, 5 Feb 2010, Mark Andrews wrote:
> > > And now for the trick question. Is ::ffff:077.077.077.077 a legal
> > > mapped address and if it, does it match 077.077.077.077?
> >
> > Forget IPv6. The first question is does 077.077.077.077 match
> > 077.077.077.077 in IPv4?
>
> I think you meant "does 077.077.077.077 match 77.77.77.77 in IPv4".
No, he had it right, because...
> > The answer is a long one full of different answers depending on
> > who's doing the parsing (gethostbyname(), inet_aton(),
> > inet_net_pton(), etc..) and on what OS. And also on many bugs.
>
> Indeed. It's a minefield out there for application developers that
> want consistancy. Even when you develop your own some OS vendor will
> go and stuff it up on you.
There's no guarantee that 2 different binaries on the same box will resolve
077.077.077.077 to the same 32-bit sequence, so it's in fact possible that
it's not even equal to itself, much less 77.77.77.77.
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