[Pdns-dev] Re: [Pdns-users] Re: Re: Domains with binary (e.g. UTF-8) labels

Benny Amorsen benny+usenet at amorsen.dk
Wed Dec 20 01:00:38 CET 2006

>>>>> "DA" == Dean Anderson <dean at av8.com> writes:

DA> Futher, the parsing of dotted DNS names can't be translated
DA> to/from ascii/wire format. For example, suppose you get a DNS
DA> record with an UTF8 name in say, hebrew. When this name is
DA> translated by an ordinary resolver/dns cache/etc from wire format
DA> to dotted format, the multibyte characters are mis-interpreted as
DA> ascii.

That won't happen. In UTF-8, all multibyte characters have the high
bit set in every byte.

DA> As soon as the ascii byte code for '.' (hex 2E) is found in
DA> the bytes of a multibyte character, the byte-by-byte translation
DA> of the wire representation sequence of labels is no longer what
DA> was intended---because there is an extra dot in the name.

Therefore that won't happen either.

DA> You also can't get a meaningful interpretation of the byte-by-byte
DA> upper/lower testing of a multi-byte character.

Luckily DNS traditionally only defines upper/lower to apply to
A-Z/a-z. The rest will just be interpreted without case folding. No

DA> Obviously, then, DNS can't support the full of UTF-8 character
DA> set, unless it gives up the dotted ascii format frequently used by
DA> DNS caches. I don't think anyone has ever advocated the full UTF-8
DA> support in discussions on namedroppers. If they did, I completely
DA> missed it, as I would have said something.

The rest of the post follows from the mistaken premises above.


Pdns-users mailing list
Pdns-users at mailman.powerdns.com

More information about the Pdns-dev mailing list