LDAP: bugfix and deprecated OpenLDAP API

I found a small bug in the implementation of LDAP connection
parameter lookup.

As documented in
http://www.postgresql.org/docs/current/static/libpq-ldap.html
processing should continue after a failed attempt
to connect to an LDAP server.

The code in src/interfaces/libpq/fe-connect.c defines a
timeout of two seconds so that this failure won't block
the libpq connection attempt for a long time.

As coded now, the timeout won't work - if the LDAP server
is down, ldap_simple_bind will wait for the network
timeout, which will be quite longer than 2 seconds.

The attached patch ldap-bug.patch fixes this problem;
unfortunately I found no way that works both with OpenLDAP
and Windows LDAP, so I had to add an #ifdef.

I think that this patch should be applied and backpatched.


I also tried to fix the problem mentioned in
http://www.postgresql.org/message-id/CA+TgmoYnj=Es3L_0Q8+ijR4tVhvztW1fb=7C9K9gEmZWqhpwuQ@mail.gmail.com
that we use deprecated OpenLDAP functions, see the attached
ldap-undeprecate.patch.

I added a file ldap.c in src/port with my own implementation
of some of the functions that OpenLDAP has deprecated.
With that, the code changes necessary are pretty minimal.

I guess it's too late for something like that to go into 9.3.
Should I add it to the next commitfest?

Yours,
Laurenz Albe