/**
  * attempt to build up a request from what was passed to the server
  */
 public static function from_request($http_method = NULL, $http_url = NULL, $parameters = NULL)
 {
     $scheme = !isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on" ? 'http' : 'https';
     $http_url = $http_url ? $http_url : $scheme . '://' . $_SERVER['HTTP_HOST'] . ':' . $_SERVER['SERVER_PORT'] . $_SERVER['REQUEST_URI'];
     $http_method = $http_method ? $http_method : $_SERVER['REQUEST_METHOD'];
     // We weren't handed any parameters, so let's find the ones relevant to
     // this request.
     // If you run XML-RPC or similar you should use this to provide your own
     // parsed parameter-list
     if (!$parameters) {
         // Find request headers
         $request_headers = sfOAuthUtil::get_headers();
         // Parse the query-string to find GET parameters
         $parameters = sfOAuthUtil::parse_parameters($_SERVER['QUERY_STRING']);
         // It's a POST request of the proper content-type, so parse POST
         // parameters and add those overriding any duplicates from GET
         if ($http_method == "POST" && isset($request_headers['Content-Type']) && strstr($request_headers['Content-Type'], 'application/x-www-form-urlencoded')) {
             $post_data = sfOAuthUtil::parse_parameters(file_get_contents(self::$POST_INPUT));
             $parameters = array_merge($parameters, $post_data);
         }
         // We have a Authorization-header with OAuth data. Parse the header
         // and add those overriding any duplicates from GET or POST
         if (isset($request_headers['Authorization']) && substr($request_headers['Authorization'], 0, 6) == 'OAuth ') {
             $header_parameters = sfOAuthUtil::split_header($request_headers['Authorization']);
             $parameters = array_merge($parameters, $header_parameters);
         }
     }
     return new sfOAuthRequest($http_method, $http_url, $parameters);
 }