function locale_string_is_safe in Drupal 7

Same name and namespace in other branches

1. 8 core/modules/locale/locale.module \locale_string_is_safe()
2. 6 includes/locale.inc \locale_string_is_safe()
3. 9 core/modules/locale/locale.module \locale_string_is_safe()

Check that a string is safe to be added or imported as a translation.

This test can be used to detect possibly bad translation strings. It should not have any false positives. But it is only a test, not a transformation, as it destroys valid HTML. We cannot reliably filter translation strings on import because some strings are irreversibly corrupted. For example, a & in the translation would get encoded to & by filter_xss() before being put in the database, and thus would be displayed incorrectly.

The allowed tag list is like filter_xss_admin(), but omitting div and img as not needed for translation and likely to cause layout issues (div) or a possible attack vector (img).

3 calls to locale_string_is_safe()

LocaleStringIsSafeTest::testLocaleStringIsSafe in modules/locale/locale.test

Tests for locale_string_is_safe().

locale_translate_edit_form_validate in modules/locale/locale.admin.inc

Validate string editing form submissions.

_locale_import_one_string_db in includes/locale.inc

Import one string into the database.

File

includes/locale.inc, line 545

Administration functions for locale.module.

Code

function locale_string_is_safe($string) {

  // Some strings have tokens in them. For tokens in the first part of href or
  // src HTML attributes, filter_xss() removes part of the token, the part
  // before the first colon.  filter_xss() assumes it could be an attempt to
  // inject javascript. When filter_xss() removes part of tokens, it causes the
  // string to not be translatable when it should be translatable. See
  // LocaleStringIsSafeTest::testLocaleStringIsSafe().
  //
  // We can recognize tokens since they are wrapped with brackets and are only
  // composed of alphanumeric characters, colon, underscore, and dashes. We can
  // be sure these strings are safe to strip out before the string is checked in
  // filter_xss() because no dangerous javascript will match that pattern.
  //
  // @todo Do not strip out the token. Fix filter_xss() to not incorrectly
  //   alter the string. https://www.drupal.org/node/2372127
  $string = preg_replace('/\\[[a-z0-9_-]+(:[a-z0-9_-]+)+\\]/i', '', $string);
  return decode_entities($string) == decode_entities(filter_xss($string, array(
    'a',
    'abbr',
    'acronym',
    'address',
    'b',
    'bdo',
    'big',
    'blockquote',
    'br',
    'caption',
    'cite',
    'code',
    'col',
    'colgroup',
    'dd',
    'del',
    'dfn',
    'dl',
    'dt',
    'em',
    'h1',
    'h2',
    'h3',
    'h4',
    'h5',
    'h6',
    'hr',
    'i',
    'ins',
    'kbd',
    'li',
    'ol',
    'p',
    'pre',
    'q',
    'samp',
    'small',
    'span',
    'strong',
    'sub',
    'sup',
    'table',
    'tbody',
    'td',
    'tfoot',
    'th',
    'thead',
    'tr',
    'tt',
    'ul',
    'var',
  )));
}