Re: [ldapext] UTF-8 full support in LDIF / LDIF v2

[Kurt Zeilenga <Kurt.Zeilenga@isode.com>]

On Jun 18, 2009, at 6:19 PM, Steven Legg wrote:

> The potential for an inadvertent change of normalization in the  
> LDIFv2 if
> it is edited doesn't overly concern me. Stringprep takes care of it  
> for
> matching purposes

Not for userPassword and the like.

Not for value syntaxes which require a specific normalization to be  
applied else result in a syntax error.

And, end-of-line characters appearing in values are not required to be  
base64'ed or otherwise escaped, there will inadvertent change of end- 
of-line characters to deal with.

LDIFv1 avoided such problems by limiting the characters in values that  
could appear without being base64'ed to a subset of the ASCII subset  
of characters.  These issues haven't gone away since the introduction  
of LDIFv1.

> and any client that expects attribute values to be in,
> or remain in, a particular normalization form is asking for trouble.

If a technical specification says an attribute value is to be in a  
particular Unicode normalization form, then all clients supporting  
that technical specification need to be provide the values of that  
attribute in a particular Unicode normalization form.

> The
> values could be modified by some other client that changes the  
> normalization
> during editing and I wouldn't count on every directory implementation
> preserving the exact character sequence it is given (though mine  
> does).

If the normalization is specified as part of the LDAP syntax for the  
attribute value syntax, it follows that there would be a requirement  
for directory servers to preserve that normalization.  Or the value  
might be stored in an octet string (like userPassword) and the server  
required to preserve the octets and hence the normalization.

> If a client needs the values to be in a particular normalization  
> form it
> should do the conversion itself.

We already have one standard attribute, userPassword, where values  
(when text) SHOULD to be provided in a particular Unicode normalization.

-- Kurt
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