web/drupal/modules/openid/openid.module
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changeset 74 0ff3ba646492
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73:fcf75e232c5b 74:0ff3ba646492
       
     1 <?php
       
     2 // $Id: openid.module,v 1.19.2.6 2009/06/10 14:05:23 goba Exp $
       
     3 
       
     4 /**
       
     5  * @file
       
     6  * Implement OpenID Relying Party support for Drupal
       
     7  */
       
     8 
       
     9 /**
       
    10  * Implementation of hook_menu.
       
    11  */
       
    12 function openid_menu() {
       
    13   $items['openid/authenticate'] = array(
       
    14     'title' => 'OpenID Login',
       
    15     'page callback' => 'openid_authentication_page',
       
    16     'access callback' => 'user_is_anonymous',
       
    17     'type' => MENU_CALLBACK,
       
    18     'file' => 'openid.pages.inc',
       
    19   );
       
    20   $items['user/%user/openid'] = array(
       
    21     'title' => 'OpenID identities',
       
    22     'page callback' => 'openid_user_identities',
       
    23     'page arguments' => array(1),
       
    24     'access callback' => 'user_edit_access',
       
    25     'access arguments' => array(1),
       
    26     'type' => MENU_LOCAL_TASK,
       
    27     'file' => 'openid.pages.inc',
       
    28   );
       
    29   $items['user/%user/openid/delete'] = array(
       
    30     'title' => 'Delete OpenID',
       
    31     'page callback' => 'drupal_get_form',
       
    32     'page arguments' => array('openid_user_delete_form', 1),
       
    33     'access callback' => 'user_edit_access',
       
    34     'access arguments' => array(1),
       
    35     'type' => MENU_CALLBACK,
       
    36     'file' => 'openid.pages.inc',
       
    37   );
       
    38   return $items;
       
    39 }
       
    40 
       
    41 /**
       
    42  * Implementation of hook_help().
       
    43  */
       
    44 function openid_help($path, $arg) {
       
    45   switch ($path) {
       
    46     case 'user/%/openid':
       
    47       $output = '<p>'. t('This site supports <a href="@openid-net">OpenID</a>, a secure way to log into many websites using a single username and password. OpenID can reduce the necessity of managing many usernames and passwords for many websites.', array('@openid-net' => 'http://openid.net')) .'</p>';
       
    48       $output .= '<p>'. t('To use OpenID you must first establish an identity on a public or private OpenID server. If you do not have an OpenID and would like one, look into one of the <a href="@openid-providers">free public providers</a>. You can find out more about OpenID at <a href="@openid-net">this website</a>.', array('@openid-providers' => 'http://openid.net/get/', '@openid-net' => 'http://openid.net')) .'</p>';
       
    49       $output .= '<p>'. t('If you already have an OpenID, enter the URL to your OpenID server below (e.g. myusername.openidprovider.com). Next time you login, you will be able to use this URL instead of a regular username and password. You can have multiple OpenID servers if you like; just keep adding them here.') .'</p>';
       
    50       return $output;
       
    51 
       
    52     case 'admin/help#openid':
       
    53       $output = '<p>'. t('OpenID is a secure method for logging into many websites with a single username and password. It does not require special software, and it does not share passwords with any site to which it is associated; including your site.') .'</p>';
       
    54       $output .= '<p>'. t('Users can create accounts using their OpenID, assign one or more OpenIDs to an existing account, and log in using an OpenID. This lowers the barrier to registration, which is good for the site, and offers convenience and security to the users. OpenID is not a trust system, so email verification is still necessary. The benefit stems from the fact that users can have a single password that they can use on many websites. This means they can easily update their single password from a centralized location, rather than having to change dozens of passwords individually.') .'</p>';
       
    55       $output .= '<p>'. t('The basic concept is as follows: A user has an account on an OpenID server. This account provides them with a unique URL (such as myusername.openidprovider.com). When the user comes to your site, they are presented with the option of entering this URL. Your site then communicates with the OpenID server, asking it to verify the identity of the user. If the user is logged into their OpenID server, the server communicates back to your site, verifying the user. If they are not logged in, the OpenID server will ask the user for their password. At no point does your site record, or need to record the user\'s password.') .'</p>';
       
    56       $output .= '<p>'. t('More information on OpenID is available at <a href="@openid-net">OpenID.net</a>.', array('@openid-net' => url('http://openid.net'))) .'</p>';
       
    57       $output .= '<p>'. t('For more information, see the online handbook entry for <a href="@handbook">OpenID module</a>.', array('@handbook' => 'http://drupal.org/handbook/modules/openid')) .'</p>';
       
    58       return $output;
       
    59   }
       
    60 }
       
    61 
       
    62 /**
       
    63  * Implementation of hook_user().
       
    64  */
       
    65 function openid_user($op, &$edit, &$account, $category = NULL) {
       
    66   if ($op == 'insert' && isset($_SESSION['openid']['values'])) {
       
    67     // The user has registered after trying to login via OpenID.
       
    68     if (variable_get('user_email_verification', TRUE)) {
       
    69       drupal_set_message(t('Once you have verified your email address, you may log in via OpenID.'));
       
    70     }
       
    71     unset($_SESSION['openid']);
       
    72   }
       
    73 }
       
    74 
       
    75 /**
       
    76  * Implementation of hook_form_alter : adds OpenID login to the login forms.
       
    77  */
       
    78 function openid_form_alter(&$form, $form_state, $form_id) {
       
    79   if ($form_id == 'user_login_block' || $form_id == 'user_login') {
       
    80     drupal_add_css(drupal_get_path('module', 'openid') .'/openid.css', 'module');
       
    81     drupal_add_js(drupal_get_path('module', 'openid') .'/openid.js');
       
    82     if (!empty($form_state['post']['openid_identifier'])) {
       
    83       $form['name']['#required'] = FALSE;
       
    84       $form['pass']['#required'] = FALSE;
       
    85       unset($form['#submit']);
       
    86       $form['#validate'] = array('openid_login_validate');
       
    87     }
       
    88 
       
    89     $items = array();
       
    90     $items[] = array(
       
    91       'data' => l(t('Log in using OpenID'), '#'),
       
    92       'class' => 'openid-link',
       
    93     );
       
    94     $items[] = array(
       
    95       'data' => l(t('Cancel OpenID login'), '#'),
       
    96       'class' => 'user-link',
       
    97     );
       
    98     
       
    99     $form['openid_links'] = array(
       
   100       '#value' => theme('item_list', $items),
       
   101       '#weight' => 1,
       
   102     );
       
   103 
       
   104     $form['links']['#weight'] = 2;
       
   105 
       
   106     $form['openid_identifier'] = array(
       
   107       '#type' => 'textfield',
       
   108       '#title' => t('Log in using OpenID'),
       
   109       '#size' => ($form_id == 'user_login') ? 58 : 13,
       
   110       '#maxlength' => 255,
       
   111       '#weight' => -1,
       
   112       '#description' => l(t('What is OpenID?'), 'http://openid.net/', array('external' => TRUE)),
       
   113     );
       
   114     $form['openid.return_to'] = array('#type' => 'hidden', '#value' => url('openid/authenticate', array('absolute' => TRUE, 'query' => drupal_get_destination())));
       
   115   }
       
   116   elseif ($form_id == 'user_register' && isset($_SESSION['openid'])) {
       
   117     // We were unable to auto-register a new user. Prefill the registration
       
   118     // form with the values we have.
       
   119     $form['name']['#default_value'] = $_SESSION['openid']['values']['name'];
       
   120     $form['mail']['#default_value'] = $_SESSION['openid']['values']['mail'];
       
   121     // If user_email_verification is off, hide the password field and just fill
       
   122     // with random password to avoid confusion.
       
   123     if (!variable_get('user_email_verification', TRUE)) {
       
   124       $form['pass']['#type'] = 'hidden';
       
   125       $form['pass']['#value'] = user_password();
       
   126     }
       
   127     $form['auth_openid'] = array('#type' => 'hidden', '#value' => $_SESSION['openid']['values']['auth_openid']);
       
   128   }
       
   129   return $form;
       
   130 }
       
   131 
       
   132 /**
       
   133  * Login form _validate hook
       
   134  */
       
   135 function openid_login_validate($form, &$form_state) {
       
   136   $return_to = $form_state['values']['openid.return_to'];
       
   137   if (empty($return_to)) {
       
   138     $return_to = url('', array('absolute' => TRUE));
       
   139   }
       
   140 
       
   141   openid_begin($form_state['values']['openid_identifier'], $return_to, $form_state['values']);
       
   142 }
       
   143 
       
   144 /**
       
   145  * The initial step of OpenID authentication responsible for the following:
       
   146  *  - Perform discovery on the claimed OpenID.
       
   147  *  - If possible, create an association with the Provider's endpoint.
       
   148  *  - Create the authentication request.
       
   149  *  - Perform the appropriate redirect.
       
   150  *
       
   151  * @param $claimed_id The OpenID to authenticate
       
   152  * @param $return_to The endpoint to return to from the OpenID Provider
       
   153  */
       
   154 function openid_begin($claimed_id, $return_to = '', $form_values = array()) {
       
   155   module_load_include('inc', 'openid');
       
   156 
       
   157   $claimed_id = _openid_normalize($claimed_id);
       
   158 
       
   159   $services = openid_discovery($claimed_id);
       
   160   if (count($services) == 0) {
       
   161     form_set_error('openid_identifier', t('Sorry, that is not a valid OpenID. Please ensure you have spelled your ID correctly.'));
       
   162     return;
       
   163   }
       
   164 
       
   165   // Store discovered information in the users' session so we don't have to rediscover.
       
   166   $_SESSION['openid']['service'] = $services[0];
       
   167   // Store the claimed id
       
   168   $_SESSION['openid']['claimed_id'] = $claimed_id;
       
   169   // Store the login form values so we can pass them to
       
   170   // user_exteral_login later.
       
   171   $_SESSION['openid']['user_login_values'] = $form_values;
       
   172 
       
   173   $op_endpoint = $services[0]['uri'];
       
   174   // If bcmath is present, then create an association
       
   175   $assoc_handle = '';
       
   176   if (function_exists('bcadd')) {
       
   177     $assoc_handle = openid_association($op_endpoint);
       
   178   }
       
   179 
       
   180   // Now that there is an association created, move on
       
   181   // to request authentication from the IdP
       
   182   // First check for LocalID. If not found, check for Delegate. Fall
       
   183   // back to $claimed_id if neither is found.
       
   184   if (!empty($services[0]['localid'])) {
       
   185     $identity = $services[0]['localid'];
       
   186   }
       
   187   else if (!empty($services[0]['delegate'])) {
       
   188     $identity = $services[0]['delegate'];
       
   189   }
       
   190   else {
       
   191     $identity = $claimed_id;
       
   192   }
       
   193 
       
   194   if (isset($services[0]['types']) && is_array($services[0]['types']) && in_array(OPENID_NS_2_0 .'/server', $services[0]['types'])) {
       
   195     $identity = 'http://specs.openid.net/auth/2.0/identifier_select';
       
   196   }  
       
   197   $authn_request = openid_authentication_request($claimed_id, $identity, $return_to, $assoc_handle, $services[0]['version']);
       
   198 
       
   199   if ($services[0]['version'] == 2) {
       
   200     openid_redirect($op_endpoint, $authn_request);
       
   201   }
       
   202   else {
       
   203     openid_redirect_http($op_endpoint, $authn_request);
       
   204   }
       
   205 }
       
   206 
       
   207 /**
       
   208  * Completes OpenID authentication by validating returned data from the OpenID
       
   209  * Provider.
       
   210  *
       
   211  * @param $response Array of returned values from the OpenID Provider.
       
   212  *
       
   213  * @return $response Response values for further processing with
       
   214  *   $response['status'] set to one of 'success', 'failed' or 'cancel'.
       
   215  */
       
   216 function openid_complete($response = array()) {
       
   217   module_load_include('inc', 'openid');
       
   218 
       
   219   if (count($response) == 0) {
       
   220     $response = _openid_response();
       
   221   }
       
   222   
       
   223   // Default to failed response
       
   224   $response['status'] = 'failed';
       
   225   if (isset($_SESSION['openid']['service']['uri']) && isset($_SESSION['openid']['claimed_id'])) {
       
   226     $service = $_SESSION['openid']['service'];
       
   227     $claimed_id = $_SESSION['openid']['claimed_id'];
       
   228     unset($_SESSION['openid']['service']);
       
   229     unset($_SESSION['openid']['claimed_id']);
       
   230     if (isset($response['openid.mode'])) {
       
   231       if ($response['openid.mode'] == 'cancel') {
       
   232         $response['status'] = 'cancel';
       
   233       }
       
   234       else {
       
   235         if (openid_verify_assertion($service['uri'], $response)) {
       
   236           // If the returned claimed_id is different from the session claimed_id,
       
   237           // then we need to do discovery and make sure the op_endpoint matches.
       
   238           if ($service['version'] == 2 && $response['openid.claimed_id'] != $claimed_id) {
       
   239             $disco = openid_discovery($response['openid.claimed_id']);
       
   240             if ($disco[0]['uri'] != $service['uri']) {
       
   241               return $response;
       
   242             }
       
   243           }
       
   244           else {
       
   245             $response['openid.claimed_id'] = $claimed_id;
       
   246           }
       
   247           $response['status'] = 'success';
       
   248         }
       
   249       }
       
   250     }
       
   251   }
       
   252   return $response;
       
   253 }
       
   254 
       
   255 /**
       
   256  * Perform discovery on a claimed ID to determine the OpenID provider endpoint.
       
   257  *
       
   258  * @param $claimed_id The OpenID URL to perform discovery on.
       
   259  *
       
   260  * @return Array of services discovered (including OpenID version, endpoint
       
   261  * URI, etc).
       
   262  */
       
   263 function openid_discovery($claimed_id) {
       
   264   module_load_include('inc', 'openid');
       
   265   module_load_include('inc', 'openid', 'xrds');
       
   266 
       
   267   $services = array();
       
   268 
       
   269   $xrds_url = $claimed_id;
       
   270   if (_openid_is_xri($claimed_id)) {
       
   271     $xrds_url = 'http://xri.net/'. $claimed_id;
       
   272   }
       
   273   $url = @parse_url($xrds_url);
       
   274   if ($url['scheme'] == 'http' || $url['scheme'] == 'https') {
       
   275     // For regular URLs, try Yadis resolution first, then HTML-based discovery
       
   276     $headers = array('Accept' => 'application/xrds+xml');
       
   277     $result = drupal_http_request($xrds_url, $headers);
       
   278 
       
   279     if (!isset($result->error)) {
       
   280       if (isset($result->headers['Content-Type']) && preg_match("/application\/xrds\+xml/", $result->headers['Content-Type'])) {
       
   281         // Parse XML document to find URL
       
   282         $services = xrds_parse($result->data);
       
   283       }
       
   284       else {
       
   285         $xrds_url = NULL;
       
   286         if (isset($result->headers['X-XRDS-Location'])) {
       
   287           $xrds_url = $result->headers['X-XRDS-Location'];
       
   288         }
       
   289         else {
       
   290           // Look for meta http-equiv link in HTML head
       
   291           $xrds_url = _openid_meta_httpequiv('X-XRDS-Location', $result->data);
       
   292         }
       
   293         if (!empty($xrds_url)) {
       
   294           $headers = array('Accept' => 'application/xrds+xml');
       
   295           $xrds_result = drupal_http_request($xrds_url, $headers);
       
   296           if (!isset($xrds_result->error)) {
       
   297             $services = xrds_parse($xrds_result->data);
       
   298           }
       
   299         }
       
   300       }
       
   301 
       
   302       // Check for HTML delegation
       
   303       if (count($services) == 0) {
       
   304         // Look for 2.0 links
       
   305         $uri = _openid_link_href('openid2.provider', $result->data);
       
   306         $delegate = _openid_link_href('openid2.local_id', $result->data);
       
   307         $version = 2;
       
   308 
       
   309         // 1.0 links
       
   310         if (empty($uri)) {
       
   311           $uri = _openid_link_href('openid.server', $result->data);
       
   312           $delegate = _openid_link_href('openid.delegate', $result->data);
       
   313           $version = 1;
       
   314         }
       
   315         if (!empty($uri)) {
       
   316           $services[] = array('uri' => $uri, 'delegate' => $delegate, 'version' => $version);
       
   317         }
       
   318       }
       
   319     }
       
   320   }
       
   321   return $services;
       
   322 }
       
   323 
       
   324 /**
       
   325  * Attempt to create a shared secret with the OpenID Provider.
       
   326  *
       
   327  * @param $op_endpoint URL of the OpenID Provider endpoint.
       
   328  *
       
   329  * @return $assoc_handle The association handle.
       
   330  */
       
   331 function openid_association($op_endpoint) {
       
   332   module_load_include('inc', 'openid');
       
   333 
       
   334   // Remove Old Associations:
       
   335   db_query("DELETE FROM {openid_association} WHERE created + expires_in < %d", time());
       
   336 
       
   337   // Check to see if we have an association for this IdP already
       
   338   $assoc_handle = db_result(db_query("SELECT assoc_handle FROM {openid_association} WHERE idp_endpoint_uri = '%s'", $op_endpoint));
       
   339   if (empty($assoc_handle)) {
       
   340     $mod = OPENID_DH_DEFAULT_MOD;
       
   341     $gen = OPENID_DH_DEFAULT_GEN;
       
   342     $r = _openid_dh_rand($mod);
       
   343     $private = bcadd($r, 1);
       
   344     $public = bcpowmod($gen, $private, $mod);
       
   345 
       
   346     // If there is no existing association, then request one
       
   347     $assoc_request = openid_association_request($public);
       
   348     $assoc_message = _openid_encode_message(_openid_create_message($assoc_request));
       
   349     $assoc_headers = array('Content-Type' => 'application/x-www-form-urlencoded; charset=utf-8');
       
   350     $assoc_result = drupal_http_request($op_endpoint, $assoc_headers, 'POST', $assoc_message);
       
   351     if (isset($assoc_result->error)) {
       
   352       return FALSE;
       
   353     }
       
   354 
       
   355     $assoc_response = _openid_parse_message($assoc_result->data);
       
   356     if (isset($assoc_response['mode']) && $assoc_response['mode'] == 'error') {
       
   357       return FALSE;
       
   358     }
       
   359 
       
   360     if ($assoc_response['session_type'] == 'DH-SHA1') {
       
   361       $spub = _openid_dh_base64_to_long($assoc_response['dh_server_public']);
       
   362       $enc_mac_key = base64_decode($assoc_response['enc_mac_key']);
       
   363       $shared = bcpowmod($spub, $private, $mod);
       
   364       $assoc_response['mac_key'] = base64_encode(_openid_dh_xorsecret($shared, $enc_mac_key));
       
   365     }
       
   366     db_query("INSERT INTO {openid_association} (idp_endpoint_uri, session_type, assoc_handle, assoc_type, expires_in, mac_key, created) VALUES('%s', '%s', '%s', '%s', %d, '%s', %d)",
       
   367              $op_endpoint, $assoc_response['session_type'], $assoc_response['assoc_handle'], $assoc_response['assoc_type'], $assoc_response['expires_in'], $assoc_response['mac_key'], time());
       
   368 
       
   369     $assoc_handle = $assoc_response['assoc_handle'];
       
   370   }
       
   371 
       
   372   return $assoc_handle;
       
   373 }
       
   374 
       
   375 /**
       
   376  * Authenticate a user or attempt registration.
       
   377  *
       
   378  * @param $response Response values from the OpenID Provider.
       
   379  */
       
   380 function openid_authentication($response) {
       
   381   module_load_include('inc', 'openid');
       
   382 
       
   383   $identity = $response['openid.claimed_id'];
       
   384 
       
   385   $account = user_external_load($identity);
       
   386   if (isset($account->uid)) {
       
   387     if (!variable_get('user_email_verification', TRUE) || $account->login) {
       
   388       user_external_login($account, $_SESSION['openid']['user_login_values']);
       
   389     }
       
   390     else {
       
   391       drupal_set_message(t('You must validate your email address for this account before logging in via OpenID'));
       
   392     }
       
   393   }
       
   394   elseif (variable_get('user_register', 1)) {
       
   395     // Register new user
       
   396     $form_state['redirect'] = NULL;
       
   397     $form_state['values']['name'] = (empty($response['openid.sreg.nickname'])) ? $identity : $response['openid.sreg.nickname'];
       
   398     $form_state['values']['mail'] = (empty($response['openid.sreg.email'])) ? '' : $response['openid.sreg.email'];
       
   399     $form_state['values']['pass']  = user_password();
       
   400     $form_state['values']['status'] = variable_get('user_register', 1) == 1;
       
   401     $form_state['values']['response'] = $response;
       
   402     $form_state['values']['auth_openid'] = $identity;
       
   403     $form = drupal_retrieve_form('user_register', $form_state);
       
   404     drupal_prepare_form('user_register', $form, $form_state);
       
   405     drupal_validate_form('user_register', $form, $form_state);
       
   406     if (form_get_errors()) {
       
   407       // We were unable to register a valid new user, redirect to standard
       
   408       // user/register and prefill with the values we received.
       
   409       drupal_set_message(t('OpenID registration failed for the reasons listed. You may register now, or if you already have an account you can <a href="@login">log in</a> now and add your OpenID under "My Account"', array('@login' => url('user/login'))), 'error');
       
   410       $_SESSION['openid']['values'] = $form_state['values'];
       
   411       // We'll want to redirect back to the same place.
       
   412       $destination = drupal_get_destination();
       
   413       unset($_REQUEST['destination']);
       
   414       drupal_goto('user/register', $destination);
       
   415     }
       
   416     else {
       
   417       unset($form_state['values']['response']);
       
   418       $account = user_save('', $form_state['values']);
       
   419       // Terminate if an error occured during user_save().
       
   420       if (!$account) {
       
   421         drupal_set_message(t("Error saving user account."), 'error');
       
   422         drupal_goto();
       
   423       }
       
   424       user_external_login($account);
       
   425     }
       
   426     drupal_redirect_form($form, $form_state['redirect']);
       
   427   }
       
   428   else {
       
   429     drupal_set_message(t('Only site administrators can create new user accounts.'), 'error');
       
   430   }
       
   431   drupal_goto();
       
   432 }
       
   433 
       
   434 function openid_association_request($public) {
       
   435   module_load_include('inc', 'openid');
       
   436 
       
   437   $request = array(
       
   438     'openid.ns' => OPENID_NS_2_0,
       
   439     'openid.mode' => 'associate',
       
   440     'openid.session_type' => 'DH-SHA1',
       
   441     'openid.assoc_type' => 'HMAC-SHA1'
       
   442   );
       
   443 
       
   444   if ($request['openid.session_type'] == 'DH-SHA1' || $request['openid.session_type'] == 'DH-SHA256') {
       
   445     $cpub = _openid_dh_long_to_base64($public);
       
   446     $request['openid.dh_consumer_public'] = $cpub;
       
   447   }
       
   448 
       
   449   return $request;
       
   450 }
       
   451 
       
   452 function openid_authentication_request($claimed_id, $identity, $return_to = '', $assoc_handle = '', $version = 2) {
       
   453   module_load_include('inc', 'openid');
       
   454 
       
   455   $ns = ($version == 2) ? OPENID_NS_2_0 : OPENID_NS_1_0;
       
   456   $request =  array(
       
   457     'openid.ns' => $ns,
       
   458     'openid.mode' => 'checkid_setup',
       
   459     'openid.identity' => $identity,
       
   460     'openid.claimed_id' => $claimed_id,
       
   461     'openid.assoc_handle' => $assoc_handle,
       
   462     'openid.return_to' => $return_to,
       
   463   );
       
   464 
       
   465   if ($version == 2) {
       
   466     $request['openid.realm'] = url('', array('absolute' => TRUE));
       
   467   }
       
   468   else {
       
   469     $request['openid.trust_root'] = url('', array('absolute' => TRUE));
       
   470   }
       
   471 
       
   472   // Simple Registration
       
   473   $request['openid.sreg.required'] = 'nickname,email';
       
   474   $request['openid.ns.sreg'] = "http://openid.net/extensions/sreg/1.1";
       
   475 
       
   476   $request = array_merge($request, module_invoke_all('openid', 'request', $request));
       
   477 
       
   478   return $request;
       
   479 }
       
   480 
       
   481 /**
       
   482  * Attempt to verify the response received from the OpenID Provider.
       
   483  *
       
   484  * @param $op_endpoint The OpenID Provider URL.
       
   485  * @param $response Array of repsonse values from the provider.
       
   486  *
       
   487  * @return boolean
       
   488  */
       
   489 function openid_verify_assertion($op_endpoint, $response) {
       
   490   module_load_include('inc', 'openid');
       
   491 
       
   492   $valid = FALSE;
       
   493 
       
   494   $association = db_fetch_object(db_query("SELECT * FROM {openid_association} WHERE assoc_handle = '%s'", $response['openid.assoc_handle']));
       
   495   if ($association && isset($association->session_type)) {
       
   496     $keys_to_sign = explode(',', $response['openid.signed']);
       
   497     $self_sig = _openid_signature($association, $response, $keys_to_sign);
       
   498     if ($self_sig == $response['openid.sig']) {
       
   499       $valid = TRUE;
       
   500     }
       
   501     else {
       
   502       $valid = FALSE;
       
   503     }
       
   504   }
       
   505   else {
       
   506     $request = $response;
       
   507     $request['openid.mode'] = 'check_authentication';
       
   508     $message = _openid_create_message($request);
       
   509     $headers = array('Content-Type' => 'application/x-www-form-urlencoded; charset=utf-8');
       
   510     $result = drupal_http_request($op_endpoint, $headers, 'POST', _openid_encode_message($message));
       
   511     if (!isset($result->error)) {
       
   512       $response = _openid_parse_message($result->data);
       
   513       if (strtolower(trim($response['is_valid'])) == 'true') {
       
   514         $valid = TRUE;
       
   515       }
       
   516       else {
       
   517         $valid = FALSE;
       
   518       }
       
   519     }
       
   520   }
       
   521   return $valid;
       
   522 }