Subject: Re: DNSEXT WGLC: Unknown types support

From: Robert Elz <[email-masked]>
Date: Fri, 23 Aug 2002 13:52:27 +0700

Date:        Thu, 22 Aug 2002 19:37:53 -0700
    From:        Scott Seligman <[email-masked]>
    Message-ID:  <[email-masked]>

  | While this is probably beyond the scope of the current discussion,

Yes...

  | The octet \115 in there happens to be in the range of ASCII, 
  | although from context one might guess that it may not represent the
  | character "S".  Would the above be mapped to:
  | 
  | 	\200\167s\199.foo.example

Yes, absolutely beyond doubt.   The DNS does not ('*' excepted) assign
any meanings to the labels in domain names - they're just sequences of
octets.

  | Although it's not clear what someone would intend with such a
  | domain name, it's a good bet that they did not intend this.

Then they didn't understand the DNS well enough to be assigning names in the
first place.

kre

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---

From: Rob Austein <[email-masked]>
Date: Fri, 23 Aug 2002 02:48:20 -0400

At Thu, 22 Aug 2002 19:37:53 -0700, Scott Seligman wrote:
> 
> While this is probably beyond the scope of the current discussion,
> the downcasing rule in RFC 2535 says:  "all domain name letters
> are set to lower case".  How does this work for a label that includes
> non-ASCII octets?

The rule still applies.  Note:

1) The RFC2535 rule only applies to computation of the "cannonical
   form" of a DNS name, which is used in place of the raw DNS name
   when computing signatures, sorting names while inserting NXT RRs,
   and so forth.  The RFC2535 rule shouldn't be read to imply that the
   original record itself has been modified in any way.

2) DNS (from RFC 883 through the present day) is case-insensitive but
   case-preserving for the range of octet values that correspond to
   the US-ASCII alphabet.  Basicly, this means that DNS preserves case
   in DNS labels when it's convenient for an implementation to do so,
   but you can't assume that case has been preserved in any particular
   DNS name (except, maybe, for the leftmost label of a DNS name).

3) I would redirect any follow-up on point (2) to the IDN WG, except
   that (a) anything that anyone could possibly say on this subject
   has almost certainly already been said there, and (b) James and
   Marc would hurt me. :)