Improve error handling in OpenID example

- properly check parameter types
- catch all exceptions (eg. network error)

Signed-off-by: Michal Čihař <michal@cihar.com>

examples/openid.php

@@ -98,9 +98,9 @@ function Show_page($contents)
 }
 
 /* Grab identifier */
-if (isset($_POST['identifier'])) {
+if (isset($_POST['identifier']) && is_string($_POST['identifier'])) {
     $identifier = $_POST['identifier'];
-} else if (isset($_SESSION['identifier'])) {
+} else if (isset($_SESSION['identifier']) && is_string($_SESSION['identifier'])) {
     $identifier = $_SESSION['identifier'];
 } else {
     $identifier = null;
@@ -109,7 +109,7 @@ function Show_page($contents)
 /* Create OpenID object */
 try {
     $o = new OpenID_RelyingParty($returnTo, $realm, $identifier);
-} catch (OpenID_Exception $e) {
+} catch (Exception $e) {
     $contents = "<div class='relyingparty_results'>\n";
     $contents .= "<pre>" . $e->getMessage() . "</pre>\n";
     $contents .= "</div class='relyingparty_results'>";