function locale_string_is_safe in Drupal 9

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. 7 includes/locale.inc \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, an & 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).

4 calls to locale_string_is_safe()

HelpTopicsSyntaxTest::verifyTopic in core/modules/help_topics/tests/src/Functional/HelpTopicsSyntaxTest.php

Verifies rendering and standards compliance of one help topic.

LocaleStringIsSafeTest::testLocaleStringIsSafe in core/modules/locale/tests/src/Kernel/LocaleStringIsSafeTest.php

Tests for locale_string_is_safe().

PoDatabaseWriter::importString in core/modules/locale/src/PoDatabaseWriter.php

Imports one string into the database.

TranslateEditForm::validateForm in core/modules/locale/src/Form/TranslateEditForm.php

Form validation handler.

File

core/modules/locale/locale.module, line 1007

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, [
    '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',
  ]));
}