fb_url_rewrite.inc

   1 <?php
   2 /**
   3  * @file
   4  * Performs custom url rewriting for Drupal for Facebook.
   5  *
   6  * These function prefix urls for canvas pages and profile tabs.  This allows
   7  * modules/fb to detect when a canvas page is requested.  This is necessary
   8  * because the facebook platform does not send us sufficient information to
   9  * detect this in some cases, particularly when the user is not logged into
  10  * facebook or has not authorized the app.  In those case, drupal could not
  11  * tell the difference between a canvas request and a regular HTML page
  12  * request without this code.  The url prefix allows us to detect that the
  13  * request is for a canvas page, and which specific application if more than
  14  * one is hosted.
  15  *
  16  * We define our custom_url rewrite function here, and not in
  17  * fb_canvas.module, because custom_url_rewrite_inbound() must be defined
  18  * *before* drupal_init_path(), which is called during DRUPAL_BOOTSTRAP_PATH,
  19  * before modules are loaded.
  20  *
  21  * If your application supports canvas pages and/or profile tabs, include this
  22  * file in your settings.php.
  23  * I.e. the end of your settings.php might look like:
  24  *
  25  * include 'sites/all/modules/fb/fb_url_rewrite.inc'; // For canvas pages support.
  26  * include 'sites/all/modules/fb/fb_settings.inc'; // Always include this.
  27  */
  28
  29 /**
  30  * Returns a list of the values which we prepend to paths when rewriting urls.
  31  */
  32 function _fb_settings_url_rewrite_prefixes() {
  33   $prefixes = &drupal_static(__FUNCTION__);
  34   if (!isset($prefixes)) {
  35     $prefixes = array(
  36       FB_SETTINGS_CB,
  37       FB_SETTINGS_CB_PAGE,
  38       FB_SETTINGS_CB_TYPE,
  39       FB_SETTINGS_CB_SESSION,
  40     );
  41   }
  42   return $prefixes;
  43 }
  44
  45 /**
  46  * Parse a setting from the URL.  This may be called before
  47  * custom_url_rewrite, so we can't count on fb_settings() to return the value.
  48  * For internal use only (see fb_session.inc).
  49  */
  50 function _fb_settings_parse($key) {
  51   // XXX will this $_GET[q] stuff still work in D7???
  52   if (isset($_GET['q'])) {
  53     $path = $_GET['q'];
  54     $pos = strpos($path, $key . '/');
  55     if ($pos !== FALSE) {
  56       // Too soon for arg() function.
  57       $args = explode('/', $path);
  58       $i = 0;
  59       while (isset($args[$i]) && isset($args[$i+1])) {
  60         if ($args[$i] == $key)
  61           // Found the value we're interested in.
  62           return $args[$i+1];
  63         $i = $i + 2;
  64       }
  65     }
  66   }
  67 }
  68
  69
  70 //// URL Management
  71
  72
  73 /**
  74  * Implements hook_url_outbound_alter().
  75  *
  76  * @param $options
  77  *   If $options['fb_url_alter'] == FALSE, this function will not alter the
  78  *   URL.  If used with $options['absolute'] == TRUE, this will generate a
  79  *   link from a canvas page out to the server's URL.
  80  */
  81 function fb_url_outbound_alter(&$path, &$options, $original_path) {
  82   if ((isset($options['external']) && $options['external']) ||
  83       (isset($options['fb_url_alter']) && $options['fb_url_alter'] === FALSE)) {
  84     return;
  85   }
  86
  87   // For most hooks, fb should come before fb_.... modules.  But in this case we want fb_canvas to act first.
  88   if (function_exists('fb_canvas_url_outbound_alter')) {
  89     fb_canvas_url_outbound_alter($path, $options, $original_path);
  90   }
  91
  92   $pre = '';
  93
  94   // Prefix each known value to the URL
  95   foreach (_fb_settings_url_rewrite_prefixes() as $prefix) {
  96     if (!isset($options[$prefix]) || $options[$prefix] !== FALSE) {
  97       if ($value = fb_settings($prefix))
  98         $pre .= $prefix . '/' . $value . '/';
  99     }
 100   }
 101
 102   if ($pre) {
 103     if ($path == '<front>') {
 104       // Do we really have to do this here?
 105       $path = '';
 106     }
 107
 108     $path =
 109       $pre .
 110       (!empty($options['prefix']) ? $options['prefix'] : '') .
 111       $path;
 112
 113     // We have manually set the prefix, so remove the options prefix.
 114     $options['prefix'] = '';
 115   }
 116
 117   // Since we called fb_canvas_url_alter already, supress it from acting again.
 118   $options['fb_url_alter'] = FALSE;
 119 }
 120
 121 /**
 122  * Implements hook_url_inbound_alter().
 123  *
 124  * Rewrite URLs for facebook canvas pages, and connect callbacks.
 125  *
 126  */
 127 function fb_url_inbound_alter(&$path, $original_path, $path_language) {
 128   global $language;
 129
 130   // See if this is a request for us.
 131   if (strpos($path, FB_SETTINGS_CB . '/') === 0) {
 132     // Too soon for arg() function.
 133     $args = explode('/', $path);
 134     while (count($args) && in_array($args[0], _fb_settings_url_rewrite_prefixes())) {
 135       $key = array_shift($args);
 136       $value = array_shift($args);
 137       if (fb_settings($key) === NULL) // defer to previously set values
 138         fb_settings($key, $value); // Store for use later.
 139     }
 140
 141     // Remove our prefixes
 142     $path = implode('/', $args);
 143
 144     // Because Drupal calls hook_url_inbound_alter() later than it should, we have to repeat this work, which path.inc has already done.
 145     if (!$path) {
 146       $path = variable_get('site_frontpage', 'node');
 147     }
 148     $alias = drupal_lookup_path('source', $path, $path_language);
 149     if ($alias) {
 150       $path = $alias;
 151     }
 152   }
 153
 154   $result = $path;
 155 }
 156