[Pdns-users] PDNS LDAP backend uses incorrect search filter for root

[Jan-Piet Mens]

I'm using the LDAP backend to PowerDNS (2.9.20) and come accross a
strange filter which shows in slapd's logs (OpenLDAP 2.3.20).

When I do a `dig @localhost . ns' searching for a root name server
(although I haven't got an appropriate entry in LDAP), I get

conn=57 op=1 SRCH base="ou=dns2,ou=dns,o=isp" scope=2 deref=3 filter="(?=undefined)"
conn=57 op=1 SRCH attr=dNSTTL aRecord nSRecord cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord rPRecord aAAARecord lOCRecord sRVRecord nAPTRRecord
conn=57 op=1 SEARCH RESULT tag=101 err=0 nentries=0 text=
conn=57 op=2 SRCH base="ou=dns2,ou=dns,o=isp" scope=2 deref=3 filter="(?=undefined)"
conn=57 op=2 SRCH attr=dNSTTL aRecord nSRecord cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord rPRecord aAAARecord lOCRecord sRVRecord nAPTRRecord
conn=57 op=2 SEARCH RESULT tag=101 err=0 nentries=0 text=
conn=57 op=3 SRCH base="ou=dns2,ou=dns,o=isp" scope=2 deref=3 filter="(&(?=undefined)(sOARecord=*))"
conn=57 op=3 SRCH attr=SOARecord dNSTTL
conn=57 op=3 SEARCH RESULT tag=101 err=0 nentries=0 text=
conn=59 fd=24 ACCEPT from IP=127.0.0.1:32868 (IP=127.0.0.1:389)
conn=59 op=0 BIND dn="" method=128
conn=59 op=0 RESULT tag=97 err=0 text=

with filter="(?=undefined)".

It would appear that the LDAP backend is searching for an attribute type
which isn't defined in any of the schemas, but I cannot find it! All
other searches for work flawlessly.

What I'm actually attempting to do is to set up a root NS in LDAP...