fb_url_rewrite.inc in Drupal for Facebook 7.3

Performs custom url rewriting for Drupal for Facebook.

These function prefix urls for canvas pages and profile tabs. This allows modules/fb to detect when a canvas page is requested. This is necessary because the facebook platform does not send us sufficient information to detect this in some cases, particularly when the user is not logged into facebook or has not authorized the app. In those case, drupal could not tell the difference between a canvas request and a regular HTML page request without this code. The url prefix allows us to detect that the request is for a canvas page, and which specific application if more than one is hosted.

We define our custom_url rewrite function here, and not in fb_canvas.module, because custom_url_rewrite_inbound() must be defined *before* drupal_init_path(), which is called during DRUPAL_BOOTSTRAP_PATH, before modules are loaded.

If your application supports canvas pages and/or profile tabs, include this file in your settings.php. I.e. the end of your settings.php might look like:

include 'sites/all/modules/fb/fb_url_rewrite.inc'; // For canvas pages support. include 'sites/all/modules/fb/fb_settings.inc'; // Always include this.

File

fb_url_rewrite.inc

<?php

/**
 * @file
 * Performs custom url rewriting for Drupal for Facebook.
 *
 * These function prefix urls for canvas pages and profile tabs.  This allows
 * modules/fb to detect when a canvas page is requested.  This is necessary
 * because the facebook platform does not send us sufficient information to
 * detect this in some cases, particularly when the user is not logged into
 * facebook or has not authorized the app.  In those case, drupal could not
 * tell the difference between a canvas request and a regular HTML page
 * request without this code.  The url prefix allows us to detect that the
 * request is for a canvas page, and which specific application if more than
 * one is hosted.
 *
 * We define our custom_url rewrite function here, and not in
 * fb_canvas.module, because custom_url_rewrite_inbound() must be defined
 * *before* drupal_init_path(), which is called during DRUPAL_BOOTSTRAP_PATH,
 * before modules are loaded.
 *
 * If your application supports canvas pages and/or profile tabs, include this
 * file in your settings.php.
 * I.e. the end of your settings.php might look like:
 *
 * include 'sites/all/modules/fb/fb_url_rewrite.inc'; // For canvas pages support.
 * include 'sites/all/modules/fb/fb_settings.inc'; // Always include this.
 */

/**
 * Returns a list of the values which we prepend to paths when rewriting urls.
 */
function _fb_settings_url_rewrite_prefixes() {
  $prefixes =& drupal_static(__FUNCTION__);
  if (!isset($prefixes)) {
    $prefixes = array(
      FB_SETTINGS_CB,
      FB_SETTINGS_CB_PAGE,
      FB_SETTINGS_CB_TYPE,
      FB_SETTINGS_CB_SESSION,
    );
  }
  return $prefixes;
}

/**
 * Parse a setting from the URL.  This may be called before
 * custom_url_rewrite, so we can't count on fb_settings() to return the value.
 * For internal use only (see fb_session.inc).
 */
function _fb_settings_parse($key) {
  if (!function_exists('request_path')) {

    // May not exist if settings.php is being include in drupal utilities that are not drupal proper.
    return;
  }

  // TODO: confirm this working in D7
  if ($path = request_path()) {
    $pos = strpos($path, $key . '/');
    if ($pos !== FALSE) {

      // Too soon for arg() function. (Actually in D7 no longer true.  We could use arg() here.)
      $args = explode('/', $path);
      $i = 0;
      while (isset($args[$i]) && isset($args[$i + 1])) {
        if ($args[$i] == $key) {

          // Found the value we're interested in.
          return $args[$i + 1];
        }
        $i = $i + 2;
      }
    }
  }
}

//// URL Management

/**
 * Implements hook_url_outbound_alter().
 *
 * @param $options
 *   If $options['fb_url_alter'] == FALSE, this function will not alter the
 *   URL.  If used with $options['absolute'] == TRUE, this will generate a
 *   link from a canvas page out to the server's URL.
 */
function fb_url_outbound_alter(&$path, &$options, $original_path) {
  if (isset($options['external']) && $options['external'] || isset($options['fb_url_alter']) && $options['fb_url_alter'] === FALSE) {
    return;
  }

  // For most hooks, fb should come before fb_.... modules.  But in this case we want fb_canvas to act first.
  if (function_exists('fb_canvas_url_outbound_alter')) {
    fb_canvas_url_outbound_alter($path, $options, $original_path);
  }
  $pre = '';

  // Prefix each known value to the URL
  foreach (_fb_settings_url_rewrite_prefixes() as $prefix) {
    if (!isset($options[$prefix]) || $options[$prefix] !== FALSE) {
      if ($value = fb_settings($prefix)) {
        $pre .= $prefix . '/' . $value . '/';
      }
    }
  }
  if ($pre) {
    if ($path == '<front>') {

      // Do we really have to do this here?
      $path = '';
    }
    $path = $pre . (!empty($options['prefix']) ? $options['prefix'] : '') . $path;

    // We have manually set the prefix, so remove the options prefix.
    $options['prefix'] = '';

    // Hack to workaround http://drupal.org/node/1801044
    $options['alias'] = TRUE;
  }

  // Since we called fb_canvas_url_alter already, supress it from acting again.
  $options['fb_url_alter'] = FALSE;
}

/**
 * Implements hook_url_inbound_alter().
 *
 * Rewrite URLs for facebook canvas pages, and connect callbacks.
 *
 */
function fb_url_inbound_alter(&$path, $original_path, $path_language) {

  // See if this is a request for us.
  if (strpos($path, FB_SETTINGS_CB . '/') === 0) {

    // Too soon for arg() function.
    $args = explode('/', $path);
    while (count($args) && in_array($args[0], _fb_settings_url_rewrite_prefixes())) {
      $key = array_shift($args);
      $value = array_shift($args);
      if (fb_settings($key) === NULL) {

        // defer to previously set values
        fb_settings($key, $value);
      }

      // Store for use later.
    }
    if (fb_settings(FB_SETTINGS_CB)) {
      if (count($args)) {
        $path = implode('/', $args);

        // remaining args
        $alias = drupal_lookup_path('source', $path, $path_language);

        //can't use drupal_get_normal_path, it calls custom_url_rewrite_inbound
        if ($alias) {
          $path = $alias;
        }
      }
      else {

        // frontpage
        $path = variable_get('site_frontpage', 'node');
        $alias = drupal_lookup_path('source', $path, $path_language);
        if ($alias) {
          $path = $alias;
        }
        $_REQUEST['destination'] = $path;

        //required workaround for compatibility with Global Redirect module, best practice?
      }
    }
  }
  else {

    //resolve aliases for non-fb-callbacks
    $alias = drupal_lookup_path('source', $path, $path_language);
    if ($alias) {
      $path = $alias;
    }
  }
  $result = $path;
}

Functions

Name	Description
fb_url_inbound_alter	Implements hook_url_inbound_alter().
fb_url_outbound_alter	Implements hook_url_outbound_alter().
_fb_settings_parse	Parse a setting from the URL. This may be called before custom_url_rewrite, so we can't count on fb_settings() to return the value. For internal use only (see fb_session.inc).
_fb_settings_url_rewrite_prefixes	Returns a list of the values which we prepend to paths when rewriting urls.