Re: [idn] length restrictions on IDN label

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

About presentation formats, you argument stands.
UTF8 form of labels further can be URLEncoded with %xx sequences into
tripled length of character streams.
That means "56 x U+AC00 " can be converted into
56 x 3 (utf8) x 3 (URLencode) = 504 octets string.
RFC1035 length restriction does not apply to presentation forms. This is
your point. right?

But, my question is about utf8 form as protocol elements (wire format
for future
application or DNS protocols), not as presentation forms.
You can find that in IDNA section 6.3.
Would you make another comments on that section ?

THanks.

Soobok Lee


Mark.Andrews@isc.org wrote:

>	The restrictions have always derived from the DNS wire format.
>	Each individual presentation format will have its own maximum
>	number of octets however just because a string fits within
>	that number of octets doesn't mean that it will be valid.
>
>	Invalid 
>	0123456789012345678901234567890123456789012345678901234567891234
>
>	Valid
>	\048\049\050\051\052\053\054\055\056\057\048\049\050\051\052\053
>
>	Both of the above presentation strings are 64 octets long.  Only
>	one is a legal label, both are < 252 octets that you would have
>	to allow to convert a arbitary label from wire format to
>	to RFC 1034 presentation format.  Similar things will happen
>	with UTF-8 as a presentation format.  Only after you have attempted
>	to covert to wire format can you determine if a arbitarty string
>	of UTF-8 characters that is less than the maximum number of octets
>	long will fit.
>
>	Mark
> 
>