function url_is_external

url_is_external($path)

Returns TRUE if a path is external to Drupal (e.g. http://example.com).

If a path cannot be assessed by Drupal's menu handler, then we must treat it as potentially insecure.

Parameters

$path: The internal path or external URL being linked to, such as "node/34" or "http://example.com/foo".

Return value

Boolean TRUE or FALSE, where TRUE indicates an external path.

File

includes/common.inc, line 2358

Common functions that many Drupal modules will need to reference.

Code

function url_is_external($path) {
  $colonpos = strpos($path, ':');
  // Some browsers treat \ as / so normalize to forward slashes.
  $path = str_replace('\\', '/', $path);
  // If the path starts with 2 slashes then it is always considered an external
  // URL without an explicit protocol part.
  return (strpos($path, '//') === 0)
    // Leading control characters may be ignored or mishandled by browsers, so
    // assume such a path may lead to an external location. The \p{C} character
    // class matches all UTF-8 control, unassigned, and private characters.
    || (preg_match('/^\p{C}/u', $path) !== 0)
    // Avoid calling drupal_strip_dangerous_protocols() if there is any slash
    // (/), hash (#) or question_mark (?) before the colon (:) occurrence - if
    // any - as this would clearly mean it is not a URL.
    || ($colonpos !== FALSE
    && !preg_match('![/?#]!', substr($path, 0, $colonpos))
    && drupal_strip_dangerous_protocols($path) == $path);
}