In message <4b6b7185.2080...@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 77.77.77.77 (and thus an IPv4 > address and not IPv6) even though internally it is written as an IPv6 > address.
You missed the point 077 is octal and 077.077.077.077 is 63.63.63.63 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 text form. > 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. > > Greets, > Jeroen > > > --------------enig57675C04A65E0982D8079586 > 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) > > iEYEARECAAYFAktrcYgACgkQKaooUjM+fCPUCQCgmwJ8u2Zqi1ljQ+PVOByv45Jv > OrgAn2iTiqdLdFWT5a9vlM6dUe6McqEO > =OqJc > -----END PGP SIGNATURE----- > > --------------enig57675C04A65E0982D8079586-- -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
