Distributed configuration of "private" IDNA (Re: IDNA and getnameinfo() and getaddrinfo())

Dave Thaler dthaler at microsoft.com
Thu Jun 17 23:45:22 CEST 2010

> -----Original Message-----
> From: idna-update-bounces at alvestrand.no [mailto:idna-update-
> bounces at alvestrand.no] On Behalf Of Nicolas Williams
> Sent: Thursday, June 17, 2010 2:41 PM
> To: Dave Thaler
> Cc: Andrew Sullivan; cheshire at apple.com; John C Klensin; idna-
> update at alvestrand.no
> Subject: Re: Distributed configuration of "private" IDNA (Re: IDNA and
> getnameinfo() and getaddrinfo())
> On Thu, Jun 17, 2010 at 09:36:40PM +0000, Dave Thaler wrote:
> > > > Hold on, there.  The DNS allows _octets_ in domain name labels.
> > > > That ...
> > >
> > > It does.  However, there's no way that anyone will bother making
> > > getaddrinfo(), DNS resolver, and application implementations that
> > > actually know when to send A-labels versus when to send something
> > > else, much less what that something else ought to be.
> >
> > Not true.   We already have many widely deployed applications that attempt
> to
> > do exactly that (IE is one of them, and there's a number of others).
> > And of course they get it wrong in corner cases, so few people notice.
> >
> > I talked about some of them near the end of the IETF plenary talk.
> Details?  Which apps, and how do they know when to do IDNA versus something
> else, and what is that something else?  Does this interop with other
> implementations?

The something else is UTF-8.

See the plenary slides.  IE tries to guess based on its application configuration
for intranet vs internet sites.  Other apps like Outlook and Windows Media Player
try one (ACE form vs UTF-8) first and then try the other.


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