Re: [dnssd] UTF8 use in DNS populated by mDNS

[Patrik Fältström <[e-mail]>]

> On 20 nov 2014, at 23:11, Andrew Sullivan <[e-mail]> wrote:
> 
> On Wed, Nov 19, 2014 at 04:50:39PM -0800, Douglas Otis wrote:
>> If UTF-8 is to be permitted in DNS populated using mDNS inputs, a
>> superset of rules directly and indirectly established to support
>> safe use of IDNA labels are necessary, otherwise omitting such
>> requirements would permit trivial spoofing.  The requirements should
>> include IDNA2008 considerations that restrict permitted code points.
> 
> In which part of the DNS-SD name do you want these restrictions?  I
> think there is considerable discussion of the different parts of those
> names in the draft I discussed in Honolulu.
> 
> Note that there is _already_ a standard for putting "UTF-8 labels" in
> the DNS (going back to STD 13 and reiterated by RFC 2181).  In effect,
> they're not "UTF-8 labels" but rather series of octets.

FWIW I agree. One either have to add some kind of restriction on Unicode Codepoints or not, and if you start to go down the path of choosing code points (including normalization forms to use etc) that also impacts matching, then you have something much more complicated than what DNSSD was intended to do (according to my view).

So, I can not personally recommend any more work be done regarding specification on Unicode and DNSSD unless there are very compelling arguments on what problems there are to solve and why.

   Patrik