[389-devel] DN normalisation design document

[Noriko Hosoi]

Thanks for your comments, Andrey!

On 03/17/2010 08:02 AM, Andrey Ivanov wrote:
> Hi Noriko,
>
> i've read the design document 
> http://directory.fedoraproject.org/wiki/Upgrade_to_New_DN_Format
>
> In order to support "Old DN format including DN in the double quotes" 
> another cn=config switch may be necessary. It seems there was recently 
> a new switch introduced to make the dn syntax validation a little more 
> "relaxed" - nsslapd-dn-validate-strict. Maybe this one could be used 
> to allow for DNs with double-quoted values?
Actually, the way how we are going to handle the old style 'dn: 
<type>="<nested dn>",<the rest>' is converting the old style to a new 
style in the normalization when the server receives DNs from clients and 
the converted new style DN is used in the rest of the process.  The 
nsslapd-dn-validate-strict value is examined in the DN syntax validation 
code for now.  Unless we change it, the DN syntax validation code always 
receives the new DN style.

That being said, are you suggesting if nsslapd-dn-validate-strict is on, 
we should not convert an old style DN to a new style?  That'd be really 
strict.  I'm leaning toward to the other side accepting the both old and 
new style with no restriction.  Do you see any disadvantages in allowing 
the old style?
>
> Here is the commit comment for that parameter :
>
> commit 0410819d48795fca4faf986cf8658c34c4d929e3
> Author: Nathan Kinder <nkinder at redhat.com <mailto:nkinder at redhat.com>>
> Date:   Wed May 13 11:12:11 2009 -0700
>
>     Add strict DN syntax enforcement option.
>
>     The DN syntax has become more restrictive over time, and the
>     current rules are quite strict. Strict adherence to the rules
>     defined in RFC 4514, section 3, would likely cause some pain to
>     client applications. Things such as spaces between the RDN
>     components are not allowed, yet many people use them still since
>     they were allowed in the previous specification outlined in RFC
>     1779.
>
>     To deal with the special circumstances around validation of the DN
>     syntax, a configuration attribute is provided named
>     nsslapd-dn-validate-strict. This configuration attribute will
>     ensure that the value strictly adheres to the rules defined in RFC
>     4514, section 3 if it is set to on. If it is set to off, the server
>     will normalize the value before checking it for syntax violations.
>     Our current normalization function was designed to handle DN values
>     adhering to RFC 1779 or RFC 2253
>
> Concerning the logic of escaping/unescaping/normalisation we could 
> test how openldap behaves in each case (as you've made it in "DN HEX 
> HEX" bug).
Yes, I did. :)  I found they are correctly handling the cases including 
escaped characters and non-ASCII UTF-8 characters in the seamless manner.
>
> For upgrades/migrations and double quotes in DNs: the two values may 
> be left during the upgrade (just in case someone uses them as-is) and 
> then an optional validation/cleaning script could be provided separately? 
All right.  That should work.  I'm adding the validation/cleaning script 
to the design memo.
> The sensitive part here is the whole o-NetscapeRoot tree: console 
> using and writing this type of values, replication 
> agreement/management etc
Indeed.
>
> As for the "related bugs" section i think another bug should be added  
> (https://bugzilla.redhat.com/show_bug.cgi?id=199923), it concernes the 
> same RFC4514 compliance.
Oops.  That's right.  I'm adding it, too.

Thanks so much for your comments.
--noriko
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