Resolver Issues (non valid hostname characters)

[Terry Lambert]

Mark.Andrews at isc.org wrote:
>         8 bit characters have ALWAYS been legal in the DNS.
> 
>         Hostnames when stored in the DNS are still restricted to
>         the characterset specified in RFC 952.  Letters, digits and
>         hyphen (LDH) for the labels.

Yes, of course.

> > The root servers were mostly switched over to totally different
> > software from bind.  8-(.
> 
>         Really.  The route operators would be very interested to
>         know this.

Sorry if the information from 14/19/25 Feb 2003 is incorrect.  The
original claim was for *all* root servers, but I see that it only
applies to the "k" root servers.

Actually, that was not what was reported/implied by Slashdot; you
may want to correct them:

http://slashdot.org/article.pl?sid=03/02/25/1635239&mode=thread&tid=95&tid=185

On the RIPE DNS and ICANN RSSAC mailing lists, it's more clear
that it only applies to the "k" servers:

http://www.ripe.net/ripe/mail-archives/dns-wg/2003/msg00044.html

and the new software vendor's press release (Dutch; sorry):

http://www.nrc.nl/W2/Nieuws/2001/04/21/Vp/wo.html


> > It's probably not very useful to talk about doing this until
> > local caching-only name servers on border servers are capable
> > of handling the 8-bit, as well.  For the RFC's that FreeBSD
> > currently complies with, it's right to be strict about this.
> 
>         Nameservers and resolvers DO NOT need to be changed to
>         support IDN.  Applications need to know how and when to
>         perform the translations.

FreeBSD's resolver library, which is what's used by local caching
DNS servers, needs to know how to deal with this -- in other words,
those servers are also in the set "applications", so they "need to
know".

The FreeBSD resolver library comes from the IPv6 KAME modified
versions of the standard "ISC bind" library reference implementation;
unfortunately, the last time this was discussed, ISC had not yet
released a new reference implementation of the resolver library
which was both fully implemented, supported IPv6 adequately from
the Japanese perspective, and supported IDN.

In addition, because the resolver is still integrated into libc,
and there is not a universal threading library support for FreeBSD,
transition to the new resolver code, which requires a threaded
implementation for some aspects, will be very difficult.  Yes,
this is a FreeBSD problem; I would personally prefer a free-standing
"libresolv", and an ELF linkage of "libc" to "libresolv", which
would make updating the library much easier, both now and in the
future.

Either way, it doesn't matter how many people bitch about not being
able to use "_" in their host names, until something other than
RFC 952 applies to host names (and to heck with the DNS issues of
putting "evil" characters into bind config files).


>         New / extended API's to lookup and return IDN's are
>         needed.  The application needs to know in advance
>         that it is going to get IHN (internationalised hostname
>         name) returned.  IHN are a subset of IDN which when
>         stored in the DNS is a subset of the legal hostnames
>         which intern are a subset of all domainnames.

Yes.

We expect these API's to come from ISC.  Since there are not any
API RFC's that are accepted as anything other than "informational"
by the IETF, the only real standard is a defacto one that comes
from a reputable source, like ISC.

We expect them to be part of a reference implementation, preferably
one which provides "optional implementation" of threads-requiring
parts of the API, so that the implementation can be split between
libc and libc_r on OS's like FreeBSD without current kernel threads
support.


> > Mostly it's still about domain name speculation, and, IMO,
> > will be for a while.  I'd say it's about as widely adopted as
> > IPv6 -- which is to say: not very.
> >
> > PS: I was on the DNSINT IETF working group for a while, FWIW.
> 
>         Well you obviously do not know what the consensus was or
>         the correct title (IDN).

It was back when it was first starting.  I can provide the emails
involved, if necessary.  8-).  After the Japanese deployment of
the UTF-5 based server, I mostly lost interest in the idea, as I
greatly dislike UTF in all its forms, since it destroys information
that I consider important, like being able to predict the size of
a host name buffer or the size of a packet required for a query,
or whether UDP can be used, or if TCP is necessary.


>         For those that want the RFC's and current drafts see
>         http://www.ietf.org/html.charters/idn-charter.html

Regards,
-- Terry