Extending LDAP Authentication with "Whitelist"

[Scott ODonnell]

All ,

I need to authenticate users against , LDAP , which I have working.
I need to also check the username against a simple whitelist.txt file before allowing access.

Where / how is the proper way to implement this?
I currently have some logic in a function called ldap_connect that is invoked using
auth.settings.login_onaccept.append(ldap_connect).

I can check the whiltelist file but it's unclear to me how to properly force a logout if the username isn't in the whitelist file.
Would it be a redirect or calling an auth function directly to insure the user is formally logged out?

-Scott