Regular Expression for IPv6 addresses
marka at isc.org
Thu Feb 4 19:53:38 CST 2010
In message <4B6B7185.2080708 at spaghetti.zurich.ibm.com>, Jeroen Massar writes:
> 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?
> ::ffff:0:0:0:0/96 should never ever be shown to a user, as it is
> confusing (is it IPv6 or IPv4?) and does not make sense at all.
> As such whatever one thinks of it, it is "illegal" in that context.
> Internally inside a program though using a 128bit sequence of memory is
> of course a great way to store both IPv6 and IPv4 addresses in one
> structure and that is where the ::ffff:0:0:0:0::/96 format is very
> useful and intended for. Of course still the representation to the user
> of addresses stored that way would be 18.104.22.168 (and thus an IPv4
> address and not IPv6) even though internally it is written as an IPv6
You missed the point 077 is octal and 077.077.077.077 is 22.214.171.124
in the IPv4 address whereas it is decimal dotted quad in a mapped
address *if* zero padded decimal dotted quad is legal in a IPv6
> As that usage is internal, you don't need any validation of the format
> as the input will be either an IPv6 or IPv4 address without any of the
> compatibility stuff, thus one does not need to handle it anyway.
> Of course, there should be only limited places where a user can enter or
> see IP addresses in the first place. There is this great thing called
> DNS which is what most people should be using.
> Content-Type: application/pgp-signature; name="signature.asc"
> Content-Description: OpenPGP digital signature
> Content-Disposition: attachment; filename="signature.asc"
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v2.0.12 (MingW32)
> -----END PGP SIGNATURE-----
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
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