need an overlay for rewriting attribute values

[Thomas Wunder <thomas.wunder@swt-bamberg.de>]

Hi,
I need some kind of overlay which allows me to rewrite attribute values. I.e. if there's an object
  "cn=a,ou=src,dc=my,dc=com" which has attributes like
     memberUid="uid=usrA,ou=rest,ou=of,dc=the,dc=dn" and
     memberUid="uid=usrB,ou=rest,ou=of,dc=the,dc=dn"
I want that overlay to suffixmassage (or whatever) it to an object like
  "cn=b,ou=dst,dc=my,dc=com" where for example
     memberUid="usrA"
     memberUid="usrB"
but the rest (i.e. other Attributes like 'gidNumber', 'userPassword', 'description',...) of the object should be identical to the 'source'-object.

The whole thing is needed because slapo-autogroup puts in full DNs as attribute values but my client programs (e.g. nss-ldapd) expect only a plain username to be there. In practical this means that I need to have that overlay to split the values of a particular type of attribute (like 'memberUid') and extract a particular part of it.

It would be very nice if it was possible to use regular expressions with backreferences for matching/rewriting the values or if there was a chance to 'plug in' an external program which accomplishes that job. (As far as i know slapo-rwm is only capable of rewriting dn's and attribute names etc. but no values, isn't it? So i need something else...)

Thanks in advance!
 Tom