In message <6eb799ab1002061452s51f9cf61p303d36130291301@mail.gmail.com>, James Hess writes:
On Fri, Feb 5, 2010 at 12:15 AM, <sthaug@nethelp.no> wrote:
And now for the trick question. =A0Is ::ffff:077.077.077.077 a legal mapped address and if it, does it match 077.077.077.077?
Wasn't there an internet draft on that subject, recently? http://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-04
077.077.077.077 is equivalent to 77.77.77.77 if valid at all RFC 4038 is very clear that the text representation of a mapped IPv4 address is Base 10. http://tools.ietf.org/html/rfc4038#section-5.1
But 077.077.077.077 is octal dotted quad. Decimal dotted quad does *not* have leading zeros. The point of allowing for dotted quad is to allow for easy mapping between IPv4 representation and IPv6 with encoded IPv4 representations. Accepting a octal representation as decimal is a bad thing and leads to none obvious failures. % ping 077.077.077.077 PING 077.077.077.077 (63.63.63.63): 56 data bytes ^C --- 077.077.077.077 ping statistics --- 4 packets transmitted, 0 packets received, 100% packet loss % "ping ::ffff:077.077.077.077" would not get to same box if my ping accepted that as a address literal which luckily it doesn't.
This is a bit like asking if "::ffff:10.1.2" is a valid IP address though.
Except it clearly isn't as there are not 4 components.
And is it the same as the ip address "10.1.2" ?
(Which of course expands to 10.1.0.2, on common implementations of inet_pton, inet_aton, and getaddrinfo) Or ::ffff:0xA010002
inet_pton() did not accept 10.1.2 when it was originally written. This was a *deliberate* decision. Some vendors have changed it to accept it but they are wrong. I can say that because I was involved in making that decision.
I would say these are perfectly valid _shorthands_ and abbreviations for entering an IP address, which may be provided by some systems, but that they are non-canonical text representations for displaying publishing or sharing IP addresses.
-- -J
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org