Re: ITS#3985 test039 hangs on Windows

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

At 02:09 PM 10/7/2005, Howard Chu wrote:
>Kurt D. Zeilenga wrote:
>>At 11:06 AM 10/7/2005, Howard Chu wrote:
>>  
>>>On the other hand, when exactly is it possible for a single request to have more than one result message?
>>>    
>>
>>In LDAP, there can be many intermediate responses (as in a search
>>entries, search references, and extended intermediate responses)
>>to a single request, but only one of those responses contains
>>the final result (as in searchResultDone).
>>  
>
>Yes, but none of those (search entry, search reference, or intermediate) responses are *Result* messages.

LDAP, at times, refers to any response as a result message:
        SearchResultEntry
        SearchResultReference
        SearchResultDone


>Notice in libldap/error.c that it explicitly excludes those three response types when looking for Result messages. Since in fact the protocol only allows *one* Result message per Request, and every new Request gets its own msgID and its own place in the request queue, I conclude that LDAP_MORE_RESULTS_TO_RETURN is an impossible condition.

A message chain can old responses from multiple requests...


>>  
>>>Googling for LDAP_MORE_RESULTS_TO_RETURN shows that at least Sun/Netscape think this can only happen as the result of a SASL Bind request.
>>>But there's nothing in the protocol spec (or LDAPbis drafts) that mentions this.
>>>    
>>
>>LDAP_MORE_RESULTS_TO_RETURN is an API error, not a protocol result
>>code, and hence not discussed in protocol specifications.
>>  
>
>I hoped some rationale would be in some IETF document somewhere. The note in the expired C API draft says it was added for LDAPv3 support.

That comment only means its a post-RFC 1823 addition.

>>>It appears that this error code has no real application, and "Find the next result..." is wasted effort. What's really going on here?
>>>    
>>
>>The API error is used in two places in libldap.  One
>>in returning a SASL_CONTINUE condition and in
>>ldap_parse_result() to indicate if more results are
>>in the chain.
>>  
>
>Yes, in libldap/cyrus.c the sasl_err2ldap() function maps SASL_CONTINUE to LDAP_MORE_RESULTS_TO_RETURN. But if you check all (4) of the places where sasl_err2ldap() is called, you'll see that it is impossible for SASL_CONTINUE to ever be input to this function. So again, that's a red herring.

Correct.  Only the latter use is relevant.

>And in ldap_parse_result in libldap/error.c, as I've already pointed out, we queue responses with their originating requests. Any LDAP Request can only have one Result message, regardless of how many intermediate messages may be included. So it appears that all accomodation for this LDAP_MORE_RESULTS_TO_RETURN error code is just excess baggage.

The only thing I can think it exists for handling of
message chains containing responses in reply to
multiple requests.


>-- 
> -- Howard Chu
> Chief Architect, Symas Corp.  http://www.symas.com
> Director, Highland Sun        http://highlandsun.com/hyc
> OpenLDAP Core Team            http://www.openldap.org/project/