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

Dean Anderson dean at av8.com
Wed Dec 20 12:25:19 CET 2006

Very good then. I stand corrected.


On 20 Dec 2006, Benny Amorsen wrote:

> >>>>> "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
> problem.
> 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.
> /Benny
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