Subject: Re: ABNF tweak for draft-zeilenga-ldapbis-rfc2253-02

From: <[email-masked]>
Date: Mon, 18 Dec 2000 19:47:58 -0500

Ok, I'll bite... what does ASCII have to do with this other 
than extending the last range to FF...

Ryan

---- Original message ----
>Date: Mon, 18 Dec 2000 16:03:33 -0800
>From: "Kurt D. Zeilenga" <[email-masked]>
>Subject: Re: ABNF tweak for draft-zeilenga-ldapbis-rfc2253-02
>To: "Ryan Moats" <[email-masked]>
>Cc: <[email-masked]>
>
>At 11:33 AM 12/10/00 -0600, Ryan Moats wrote:
>>I'd suggest
>>
>>   quotechar = %x00-%x21 / %x23-%x5B / %x5D-7F ; any 
character except "\" or
>>QUOTATION
>
>Note that any character is not restricted to ASCII.
>
>Kurt
>

---

From: "Kurt D. Zeilenga" <[email-masked]>
Date: Mon, 18 Dec 2000 16:52:30 -0800

>than extending the last range to FF...

Extending the range to FF is not sufficient.  The ISO-10646-1
character code range, IIRC, is 0x000000 - 0x7FFFFFFF.  When
presented as UTF-8, each character spans from 1 to 6 octets
(derived from RFC2849):

UTF8-CHAR                = ASCII / UTF8-2 / UTF8-3 /
                           UTF8-4 / UTF8-5 / UTF8-6
UTF8-1                   = %x80-BF
UTF8-2                   = %xC0-DF UTF8-1
UTF8-3                   = %xE0-EF 2UTF8-1
UTF8-4                   = %xF0-F7 3UTF8-1 
UTF8-5                   = %xF8-FB 4UTF8-1
UTF8-6                   = %xFC-FD 5UTF8-1
ASCII                    = %x00-7F

Your original suggestion would limit escaping to only ASCII
characters.  With the range extension, the escaping would
apply to the first octet of the character, not to the whole
character.

Kurt

---

From: "Ryan Moats" <[email-masked]>
Date: Tue, 19 Dec 2000 08:36:56 -0600

Please, I understand UNICODE and laud what you are saying here.
However, my reading is that the draft covers this already,
because quotechar only shows up in:

string     = *( stringchar / pair )
             / "#" hexstring
             / QUOTATION *( quotechar / pair ) QUOTATION

so quotechar only needs to go to 0xFF as that covers all of the 
UTF-8 encoding.

I agree that the ABNF below is more specific, but I don't see
how changing quote character to -0xFF (and yes I got that
wrong the first time), breaks any of the examples in the draft.

Ryan

-----Original Message-----
From: Kurt D. Zeilenga [mailto:[email-masked]]
Sent: Monday, December 18, 2000 6:53 PM
To: [email-masked]
Cc: [email-masked]
Subject: Re: ABNF tweak for draft-zeilenga-ldapbis-rfc2253-02

Kurt

---

From: "Phillip H. Griffin" <[email-masked]>
Date: Tue, 19 Dec 2000 11:45:30 -0500

Hi there,

It might be a good idea to not rely too heavily on
everything that may appear in RFC 2849, but to consider
using the most current materials from the unicode site,
and to rely on the precise definitions of the restricted
character string types found in the ASN.1 standards. See 
www.unicode.org/unicode/uni2errata/UTF-8_Corrigendum.html
for a discussion relevant to the notion of the 5 and 6
byte sequences listed below. 

Note that the changes described at this link are very much
in line with the long held notion in ASN.1 of string types
whose values are said to be "restricted". Much is simply 
not allowed by the ASN.1 standards for such types (BOMs, 
escapes to other character sets) for the sole purpose of
promoting secure interworking between applications.

Phil
----
Phillip H. Griffin      Griffin Consulting
http://asn-1.com        Secure ASN.1 Design & Implementation
+1-919-832-7008         1625 Glenwood Avenue, Five Points
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