wikimedia/css-sanitizer

Classes to parse and sanitize CSS

![Latest Stable Version] ![License], _(*1)

Wikimedia CSS Parser & Sanitizer

This library implements a CSS tokenizer, parser and grammar matcher in PHP., _(*2)

Usage

use Wikimedia\CSS\Parser\Parser;
use Wikimedia\CSS\Sanitizer\StylesheetSanitizer;

/** Parse a stylesheet from a string **/

$parser = Parser::newFromString( $cssText );
$stylesheet = $parser->parseStylesheet();

/** Report any parser errors **/

foreach ( $parser->getParseErrors() as list( $code, $line, $pos ) ) {
    // $code is a string that should be suitable as a key for an i18n library.
    // See errors.md for details.
    $error = lookupI18nMessage( "css-parse-error-$code" );
    echo "Parse error: $error at line $line character $pos\n";
}

/** Apply sanitization to the stylesheet **/

// If you need to customize the defaults, copy the code of this method and
// modify it.
$sanitizer = StylesheetSanitizer::newDefault();
$newStylesheet = $sanitizer->sanitize( $stylesheet );

/** Report any sanitizer errors **/

foreach ( $sanitizer->getSanitizationErrors() as list( $code, $line, $pos ) ) {
    // $code is a string that should be suitable as a key for an i18n library.
    // See errors.md for details.
    $error = lookupI18nMessage( "css-sanitization-error-$code" );
    echo "Sanitization error: $error at line $line character $pos\n";
}

/** Convert the sanitized stylesheet back to text **/

$newText = (string)$newStylesheet;

// Or if you'd rather have it minified too
$minifiedText = Wikimedia\CSS\Util::stringify( $newStylesheet, [ 'minify' => true ] );

Conformance

The library follows the following grammar specifications:, _(*3)

• CSS Syntax Level 3, 2019-07-16
• CSS Values and Units Module Level 4, 2024-03-12
• CSS Selectors Level 3, 2018-11-06

The sanitizer recognizes the following CSS modules:, _(*4)

• Align Level 3, 2018-12-06
• Animations Level 1, 2018-10-11
• Backgrounds Level 3, 2017-10-17
• Break Level 3, 2018-12-04
• Cascade Level 4, 2018-08-28
• Color Level 4, 2025-04-24
• Compositing Level 1, 2015-01-13
• Counter Styles Level 3, 2021-07-27
• CSS Level 2, 2011-06-07
• Display Level 3, 2023-03-30
• Filter Effects Level 1, 2018-12-18
• Flexbox Level 1, 2018-11-19
• Fonts Level 3, 2018-09-20
• Grid Level 1, 2017-12-14
• Images Level 3, 2019-10-10
• Lists and Counters Level 3, 2020-11-17
• Logical Properties and Values Level 1, 2018-08-27
• Masking Level 1, 2014-08-26
• Multicol Level 1, 2019-10-15
• Overflow Level 3, 2023-03-29
• Overflow Level 4, 2023-03-21
• Page Level 3, 2018-10-18
• Position Level 3, 2016-05-17
• Ruby Level 1, 2022-12-31
• Selectors Level 4, 2019-02-25
• Shapes Level 1, 2014-03-20
• Sizing Level 3, 2021-12-17
• Sizing Level 4, 2025-02-24
• Text Level 3, 2019-11-13
• Text Decorations Level 3, 2019-08-13
• Easing Level 1, 2019-04-30
• Transforms Level 1, 2019-02-14
• Transforms Level 2, 2021-11-09
• Transitions Level 1, 2018-10-11
• UI 3 Level 3, 2018-06-21
• UI 4 Level 4, 2020-01-02
• Writing Modes Level 4, 2019-07-30

And also, * The touch-action property from Pointer Events Level 2, 2019-04-04 * :dir() pseudo-class from Selectors Level 4, 2022-11-11 * Accessibility related media features from Media Queries Level 5 including prefers-reduced-motion, prefers-reduced-transparency, prefers-contrast and forced-colors. * light-dark() color function from Color Module Level 5, 2024-02-29, _(*5)

Running tests

composer install --prefer-dist
composer test

Adding properties

CSS specifications typically contain a summary of value grammars in the property index section. These value grammars map directly to PHP code., _(*6)

Component value types, _(*7)

Component value combinators, _(*8)

Component value multipliers, _(*9)

Releasing a new version

This package uses wikimedia/update-history and its conventions., _(*10)

See https://www.mediawiki.org/wiki/UpdateHistory for details., _(*11)

History

We required a CSS sanitizer with several properties:, _(*12)

• Strict parsing according to modern standards.
• Includes line and character position for all errors.
• Configurable to limit unsafe constructs such as external URL references.
• Errors are easily localizable.

We could not find a library that fit these requirements, so we created one., _(*13)

Additional release history is in HISTORY.md., _(*14)