'Searches LDAP for user, assumes ldap_search is set.
:param ldap: The ldap module reference
:param con: The ldap connection
:param username: username to match with auth_ldap_uid_field
:return: ldap object array'

def _search_ldap(self, ldap, con, username):

    if self.auth_ldap_append_domain:
        username = ((username + '@') + self.auth_ldap_append_domain)
    filter_str = ('%s=%s' % (self.auth_ldap_uid_field, username))
    user = con.search_s(self.auth_ldap_search, ldap.SCOPE_SUBTREE, filter_str, [self.auth_ldap_firstname_field, self.auth_ldap_lastname_field, self.auth_ldap_email_field])
    if user:
        if (not user[0][0]):
            return None
    return user
