Closing

   The following functions are used to unbind from the directory,
   close the connection, and dispose of the session handle.

           int ldap_unbind( LDAP *ld );
           int ldap_unbind_s( LDAP *ld );

   Parameter is as follows:

   ld    The session handle.

   The ldap_unbind() and ldap_unbind_s()  functions both work
   synchronously, unbinding from the directory, closing the
   connection, and freeing up the ld structure before returning.
   There is no server response to an unbind operation. The ldap_
   unbind() function returns LDAP_SUCCESS (or another LDAP error
   code if the request cannot be sent to the LDAP server). After a
   call to ldap_unbind() or ldap_unbind_s(),  the session handle ld
   is invalid and it is illegal to make any further LDAP API calls
   using ld.