Subject: [Enum] IRIs in ENUM

From: Alexander Mayrhofer <[email-masked]>
Date: Mon, 11 Sep 2006 10:37:08 +0200

Hi,

i'm thinking about issues regarding use of IRIs with ENUM, with the work on
3761bis in mind. I'd appreciate comments on what i've found so far:

- RFC3761 refers from E.164 numbers to URI, hence the replacement part of
the regexp field must contain a URI.
- RFC3987, Section 3 specifies how to map IRIs to URIs - essentially, this
produces a "urlencoded" UTF-8 representation of the IRI (%HH style notation).
- RFC3761 states at the end of section 2.4 that "The character set used to
encode the substitution expression is UTF-8", but doesn't say anything about
percent-encoding.

Issues regarding the regex operation itself:

- The application unique string for ENUM contains only digits. Those should
  go through the IRI->URI encoding process unaffected.
- Therefore, matches and backreference results should only contain digits as
well. Since those digits should never occur "percent encoded", the regex
implementation does not need to be aware of that encoding.
- Same for the result after backreferences have been applied. No encoding
neccessary, because only digits can be added.

So, considering that 3761 came out before 3987, i think that 3761bis should
explicitely mention IRIs, and state something like "IRIs cannot be directly
used with ENUM, but MUST be converted to URIs according to Section 3 of
RFC3987".

That would imho assure that the result from ENUM would alway be plain ASCII,
even when IRIs are used.

comments?

Alex

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---

From: lconroy <[email-masked]>
Date: Mon, 11 Sep 2006 13:56:47 +0100

Hi folks,
  I can't resist it. See section 3 of the Experiences draft.
all the best,
   Lawrence

> 3761bis in mind. I'd appreciate comments on what i've found so far:
<IRIs considered harmful>
<snip>
> That would imho assure that the result from ENUM would alway be  
Precisely true, but perhaps slightly misleading.
e.g. an HTTP URI will have percent encoded characters if there are  
characters
in it that are not in the URI scheme's unescaped character group.
It's still encoded and the Web Server receiving a subsequent request  
would
probably have to urldecode before use.
<snip>

---

From: Alexander Mayrhofer <[email-masked]>
Date: Mon, 11 Sep 2006 15:19:28 +0200

>  I can't resist it. See section 3 of the Experiences draft.

Hi Lawrence,

i actually expected that mail. However, we now have an RFC which specifies
how to map IRIs to URIs, and IRI schemes are starting to pop up - so we have
to do something about it.

(not very productive, this message, i know ;)

cheers

Alex

---

From: lconroy <[email-masked]>
Date: Mon, 11 Sep 2006 18:53:41 +0100

Hi Alex, folks,
  OK - my mail did not include enough detail.
(i)  Section 3 (and particularly section 3.1) of the unloved  
Experiences draft
has already covered this, including the explanation, justification  
and the
proposed restrictions.
(ii) I hope that everyone agrees that It Would Be Bad if rfc3761bis  
were to be
incompatible with the existing clients (and provisioning systems)  
"out there".
Thus it is pretty much necessary to mention IRIs, and then preclude  
them in
their "naked" form. You also need to mention (and consider) IDNs, IMHO.

Just Cut'n'paste section 3.1 of Experiences and you're probably done.
[assuming that normative restrictions are OK in 3761bis :].

atb,  L