Re: [idn] length restrictions on IDN label

[Soobok Lee <lsb@postel.co.kr>]

James Seng wrote:

> Therefore, a UTF-8 string which was somehow squeeze into the DNS packet has
> no meaning right now.
>
> IDNA do not ignore the possibility of using UTF-8 in DNS Packet. But the use
> is yet to be defined. Until it is defined, it is useless to discuss that
> possibility.
>
>  
Your argument stands only in DNS on-the-wire context. IN all other 
protocol/display
contexts, utf8 labels are legitimate domain labels. That is why zone 
admins may input
their labels in utf8 into their zone files and end users recoginze them 
as  domain names.

Moreover,
I didn't limit my question into  DNS and its protocols (just 'protocol', 
DNS is not the  'all')
Rather, that may span into all application protocols that use domain names,
like future ESMTP.

There will be many application protocols (IETF's or home-made) that
may exchange utf8-form labels as protocols elements (not for human eyes)
according to IDNA section 6.1-3. IDNA draft granted such use of utf8
labels as legitimate one.

Length restriction should be clarified before  IDN  deployments.
Currently valid IDN label should not be invalidated in the future due to
today's misspecifications.

To avoid  buffer overflow errors and security breaches, label length issues
are practically important to implementors who want to estimate enough 
buffer
spaces for IDN labels.

Soobok Lee