ext/ldap: Allow default host from ldap.conf to work.

[caldwell]

This fixes an regression introduced in e7af0fe. Previously, calling ldap_connect() with no parameters would pass NULL to ldap_init(), which causes it to use the default host specified in /etc/ldap/ldap.conf (on Ubuntu).

When the code changed to use ldap_initialize(), it initialized a uri, even if there were no parameters passed to ldap_connect(). Because of this, there's no way to pass a NULL into ldap_initialize(), making it impossible to use the default uri from ldap.conf.

This commit bypasses the uri creation when there is no host argument, passing on a NULL to ldap_initialize() which restores the old PHP 5.5 behavior.

[andrewnester]

@caldwell I guess it would great to add test to check this case

[caldwell]

@andrewnester, I attempted a test and it appears to work. It's a little hairy since it needs to write an ldap.conf file and set an env var to test for it, so I'm worried about cross-platform stuff (is OpenLDAP a thing on Windows?) I'm also not super happy about the way I'm detecting whether PHP is using OpenLDAP (phpinfo() + a regexp). If there's a better way, I open to suggestions.

[andrewnester]

@caldwell do we need setting conf file? what if we just skip this step?

as to checking for OpenLDAP - I am not sure that you need to check and skip if it's not because it looks like internal implementation of LDAP and we could ignore it just making sure that for end user it works as expected in any of configuration

[caldwell]

The idea was to test that it would pick up defaults from the conf file when there are no arguments to ldap_connect(). I don't know how to test that without setting up a conf file. Without being limited to OpenLDAP and without the conf file, ldap_connect() would not choose a reliable default, and so the test wouldn't really be able to verify anything.

Maybe I'm misunderstanding what you want to test?

[andrewnester]

@caldwell yes, i tried to dive deeper in this the code and it seems reasonable. Thanks!