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Re: LDAP Extension Style Guide, re interaction between controls



Date sent:      	Wed, 23 Aug 2000 09:58:11 -0700
To:             	d.w.chadwick@salford.ac.uk
From:           	"Kurt D. Zeilenga" <Kurt@OpenLDAP.org>

> I suggest ignore both under the general principle of least
> astonishment.  I suggest:
> 
> An operation may be extended by one or more controls.  If the
> combination of controls is unrecognized, undefined, or the
> server is otherwise unwilling to perform the operation as
> extended by the sequence of provided controls,
>   if any of the controls are marked critical, the server
>   SHALL return unavailableCriticalExtension,

I dont like this. Under the principle of "the server should do its best 
to provide a useful service", it should obey the known critical 
extension and ignore the non-critical ones.

This was the suggested text that I sent to PKIX list that 
unfortunately you did not receive (see below)


" A validation engine that does not understand the interaction of a 
non-critical extension with another extension (critical or non-critical),
may ignore the non-critical extension (even if it understands the
semantics of the extension in isolation to the others), and accept the
certificate (unless factors other than this extension cause it to be
rejected).

A validation engine that does not understand the interaction of two 
critical extensions, must reject the certificate (even if it understands
the semantics of both extensions in isolation to each other)."

>   otherwise the server SHALL perform the operation as if
>   no controls were provided.
> 
> That is, combined control semantics is all or nothing.
> 
> 

My messages directly to you are getting bounced as follows:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. The following address(es) failed:

  Kurt@OpenLDAP.org:
    SMTP error from remote mailer after MAIL
    FROM:<d.w.chadwick@salford.ac.uk>: host mail.openldap.org
    [204.152.186.51]: 550 5.0.0 Rejected - see
    http://www.mail-abuse.org/rss/

This means that you did NOT get a copy about this topic that I sent 
to the PKIX group. They are now following up on this, and are 
proposing to produce a table of allowed extensions that can be 
used in combinations. Is this something that LDAPExt should do?

David

P.s could the bouncing be due to my newly installed firewall that 
ignores messages from unknown hosts (I am operating in stealth 
mode). I noticed that I received an unidentified message 
immediately after sending an email to you. Are you testing out 
senders to see if they exist?

***************************************************

David Chadwick
IS Institute, University of Salford, Salford M5 4WT
Tel +44 161 295 5351  Fax +44 161 745 8169
Mobile +44 790 167 0359
Email D.W.Chadwick@salford.ac.uk
Home Page  http://www.salford.ac.uk/its024/chadwick.htm
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Entrust key validation string MLJ9-DU5T-HV8J

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