function locale_string_is_safe

locale_string_is_safe($string)

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 \Drupal\Component\Utility\Xss::filter() before being put in the database, and thus would be displayed incorrectly.

The allowed tag list is like \Drupal\Component\Utility\Xss::filterAdmin(), but omitting div and img as not needed for translation and likely to cause layout issues (div) or a possible attack vector (img).

File

core/modules/locale/locale.module, line 1037

Enables the translation of the user interface to languages other than English.

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, \Drupal\Component\Utility\Xss::filter() removes part
  // of the token, the part before the first colon.
  // \Drupal\Component\Utility\Xss::filter() assumes it could be an attempt to
  // inject javascript. When \Drupal\Component\Utility\Xss::filter() removes
  // part of tokens, it causes the string to not be translatable when it should
  // be translatable.
  // @see \Drupal\Tests\locale\Kernel\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
  // \Drupal\Component\Utility\Xss::filter() because no dangerous javascript
  // will match that pattern.
  //
  // Strings with tokens should not be assumed to be dangerous because even if
  // we evaluate them to be safe here, later replacing the token inside the
  // string will automatically mark it as unsafe as it is not the same string
  // anymore.
  //
  // @todo Do not strip out the token. Fix
  //   \Drupal\Component\Utility\Xss::filter() to not incorrectly alter the
  //   string. https://www.drupal.org/node/2372127
  $string = preg_replace('/\[[a-z0-9_-]+(:[a-z0-9_-]+)+\]/i', '', $string);

  return Html::decodeEntities($string) == Html::decodeEntities(Xss::filter($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')));
}