Re: About rewrite contexts for search operations in meta-backend

["Pierangelo Masarati" <ando@sys-net.it>]

>     Hi all,
>     I have a doubt about how the rewriting works for search operations,
> the question is: Is it possible to use the information in the search
> filter to rewrite the search base? By reading the documentation, it
> seems it's possible to do this by using variable assignment and
> dereferencing (with operators &, &&, *, and **), but I've tried to do it
>  without any success. It seems like in a search operation the searchBase
>  rewrite context is evaluated before the searchfilter one, is this the
> case?

Exactly.

>     I want to rewrite the search base depending of what is received in
> the search filter, so I've something like this in my configuration file:
>
> uri             "ldap://localhost:30389/ou=subscribers,o=company";
> rewriteEngine   on
> rewriteParam    subs1 subscribers1
> rewriteParam    subs2 subscribers2
> rewriteContext  searchFilter
> rewriteRule     "(.*)[0-9]*1" "%{&&therdn(%{$subs1})}%0" ":"
> rewriteRule     "(.*)[0-9]*2" "%{&&therdn(%{$subs2})}%0" ":"
> rewriteContext  searchBase
> rewriteRule     "(.*)ou=subscribers,o=company"
> "%1ou=%{**therdn},o=company" "@"
>
>     And when I do the search operation, the error I have is:
>
> connection_get(7)
> send_ldap_result: err=0 matched="" text=""
> connection_get(7)
> SRCH "ou=subscribers,o=company" 2 0    0 0 0
>     filter: (SearchOn=mms00000000001)
>     attrs:
> request 1 done
> ==> rewrite_context_apply error ...
> send_ldap_result: err=80 matched="" text="rewrite error"
> connection_get(7)
>
>     I've seen this error happens in the rewriting rule of the searchBase
>
> rewriteContext, and I suspect this is because the "therdn" variable
> hasn't been initialised, because the searchBase rewriteContext evaluates
>  before the searchFilter one, is this the reason? It's possible to do
> what I intend in some other way with the meta or ldap back-end, and in
> that case, what would be the proper way to configure it?

You can hack the backend search routine (back-{ldap|meta}/search.c)
to process the filter before the search base; a cleaner solution
would be to populate the session with the strings that are significant
in form of variables, e.g. use rewrite_session_var_set_f() to inject
base, filter and so before all of them are rewritten.  Something
like this will be done in the rewrite-remap overlay I'm writing
for slapd 2.2.



-- 
Pierangelo Masarati
mailto:pierangelo.masarati@sys-net.it