About rewrite contexts for search operations in meta-backend

[Anibal Caceres Hernando <anibal.caceres@ericsson.com>]

   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?
   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?

   Thank you very much in advance.
   Kind regards,

   Aníbal Cáceres.