Menu callback; OpenID Provider Endpoint.
It accepts "associate" requests directly from the Relying Party, and "checkid_setup" requests made by the user's browser based on HTTP redirects (in OpenID 1) or HTML forms (in OpenID 2) generated by the Relying Party.
function openid_test_endpoint() {
switch ($_REQUEST['openid_mode']) {
case 'associate':
_openid_test_endpoint_associate();
break;
case 'checkid_setup':
_openid_test_endpoint_authenticate();
break;
}
}