function 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).

File

includes/locale.inc, line 545

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',
    )));
}