[Standards] IDN Names and NodePrep
chris.mullins at coversant.net
Tue Jul 3 01:48:13 UTC 2007
That verbage makes the answer clear. Thanks!
I'm not in the habit yet of checking the bis revisions of the specs.
I'll have to change that, and make it my starting point.
From: standards-bounces at xmpp.org [mailto:standards-bounces at xmpp.org] On
Behalf Of Peter Saint-Andre
Sent: Monday, July 02, 2007 3:54 PM
To: XMPP Extension Discussion List
Subject: Re: [Standards] IDN Names and NodePrep
Chris Mullins wrote:
> This is probably a silly question, but it's been giving me a hard time
> for a bit now.
> Is "!.com" (without the quotes) a valid JID?
> The definition of a JID is:
> A domain identifier MUST be an "internationalized domain name"
> as defined in [IDNA], to which the Nameprep [NAMEPREP]
> profile of stringprep [STRINGPREP] can be applied
> without failing.
>>From this definition, "!.com" passes all the rules.
> None of the prohibited tables list "!" in them anywhere (or " "
> as far as I can tell.
> IDNA does talks about LDH characters (which would means a "!" is
> invalid), and it talks about them in the context of having a
> UseSTD3ASCIIRules flag. I can't determine if I should be using this or
A domain identifier MUST be an "internationalized domain name" as
defined in [IDNA], that is, "a domain name in which every label is an
internationalized label". When preparing a text label (consisting of
a sequence of Unicode code points) for representation as an
internationalized label in the process of constructing an XMPP domain
identifier or comparing two XMPP domain identifiers, an application
MUST ensure that for each text label it is possible to apply without
failing the ToASCII operation specified in [IDNA] with the
UseSTD3ASCIIRules flag set (thus forbidding ASCII code points other
than letters, digits, and hyphens). If the ToASCII operation can be
applied without failing, then the label is an internationalized
label. An internationalized domain name (and therefore an XMPP
domain identifier) is constructed from its constituent
internationalized labels by following the rules specified in [IDNA].
(Note: The ToASCII operation includes application of the [NAMEPREP]
profile of [STRINGPREP] and encoding using the algorithm specified in
[PUNYCODE]; for details, see [IDNA].)
> Common sense says "yes" we should require this flag, but the more I
> the spec, the more I think, "no". Specifically the phrase (from RFC
> An "internationalized label" is a label to which the ToASCII
> operation (see section 4) can be applied without failing
> (with the UseSTD3ASCIIRules flag unset).
> Can any of the IDNA / Unicode guru's on this list help me answer this?
RTFM did the trick this time. Do you think I write these specs for the
fun of it? ;-)
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