Multiple search bases against iPlanet LDAP for Apache 2

[Nigel Cole <nimba@sc98c.demon.co.uk>]

What is the recommended way of searching multiple search bases?

Situation: I run an Apache web server that authenticates against an
iPlanet directory server holding several disjoint search bases (c=gb,
c=de, etc). The server also has a single search base that also acts as a
referrer for the others; unfortunately, this doesn't work with OpenLDAP,
because the bases are disjoint and OpenLDAP expects referrals to be
across identical databases (which is what the RFC says). I believe the
iPlanet server is running LDAP v3, but I don't have access to its
configuration and I'm unlikely to be able to get any changes made to it.

I currently use a heavily-modified mod_ldap to search each search base
in turn. However, I'd like to move to Apache 2 and use its
mod_auth_ldap, which only uses a single search base. Is there any way of
searching multiple disjoint search bases from a single search base?

(I've asked this on the Apache users mailing list, but they suggested I
ask here instead.)
--
Dr. Nigel Cole