Re: (ITS#6504) Corrupted control value when using pagedresults with subordinate *ldap* database

[hyc@symas.com]

masarati@aero.polimi.it wrote:
>> masarati@aero.polimi.it wrote:
>>>> Also, I note that the glued paged response seems to work incorrectly.
>>>> I
>>>> made a simple test system, where the root database contains exactly one
>>>> entry (the suffix) and a back-ldap is glued on top.  If I request
>>>> entries
>>>> with a page size of 2, searching the suffix return 3 entries;
>>>> subsequent
>>>> searches return 2 entries from the proxy.  I haven't figured out yet
>>>> where
>>>> the issue is.
>>>
>>> I figured out how to fix the issue you reported.  It is related to the
>>> fact that slapd internally assumes that ldctl_oid values are constant
>>> strings, so it doesn't duplicate nor free them.  However, control OIDs
>>> returned by back-ldap (and friends) have been decoded from the wire by
>>> the
>>> client library, so they are actually malloc'ed.  That's why backglue
>>> ends
>>> up with a dangling pointer.
>>>
>>> I'm fixing it by having backglue duplicate (and free) control OIDs
>>> consistently.  Another option would be to replace those values with
>>> constant strings for known control values.  This would prevent gluing
>>> for
>>> unknown proxied controls.
>>
>> Or just tmpalloc them and don't bother to clean them up.
>
> Yes, I've reworked all the temporary controls allocation using tmpalloc.
> Too bad OIDs are char* and not bervals.
>
> With respect to the other issue, to honor the requested pagesize we'd need
> to intercept pagedresult requests, modify the page size in the request
> when a page crosses two databases, requesting the original page size minus
> entries already returned.  I wonder whether it's worth the effort, though.

IMO pagedresults should be a (global) overlay, and backends shouldn't do 
anything about it. Note that the sssvlv overlay already intercepts 
pagedresults, it's impossible to handle things correctly otherwise.

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