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class-amp-style-sanitizer.php
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<?php
/**
* Class AMP_Style_Sanitizer
*
* @package AMP
*/
use \Sabberworm\CSS\RuleSet\DeclarationBlock;
use \Sabberworm\CSS\CSSList\CSSList;
use \Sabberworm\CSS\Property\Selector;
use \Sabberworm\CSS\RuleSet\RuleSet;
use \Sabberworm\CSS\Rule\Rule;
use \Sabberworm\CSS\Property\AtRule;
use \Sabberworm\CSS\CSSList\KeyFrame;
use \Sabberworm\CSS\RuleSet\AtRuleSet;
use \Sabberworm\CSS\Property\Import;
use \Sabberworm\CSS\CSSList\AtRuleBlockList;
use \Sabberworm\CSS\Value\RuleValueList;
use \Sabberworm\CSS\Value\URL;
/**
* Class AMP_Style_Sanitizer
*
* Collects inline styles and outputs them in the amp-custom stylesheet.
*/
class AMP_Style_Sanitizer extends AMP_Base_Sanitizer {
/**
* Styles.
*
* List of CSS styles in HTML content of DOMDocument ($this->dom).
*
* @since 0.4
* @var array[]
*/
private $styles = array();
/**
* Stylesheets.
*
* Values are the CSS stylesheets. Keys are MD5 hashes of the stylesheets
*
* @since 0.7
* @var string[]
*/
private $stylesheets = array();
/**
* Current amp-custom CSS size.
*
* Sum of CSS located in $styles and $stylesheets.
*
* @var int
*/
private $current_custom_size = 0;
/**
* Spec for style[amp-custom] cdata.
*
* @since 1.0
* @var array
*/
private $style_custom_cdata_spec;
/**
* The style[amp-custom] element.
*
* @var DOMElement
*/
private $amp_custom_style_element;
/**
* The found style[amp-keyframe] stylesheets.
*
* @since 1.0
* @var string[]
*/
private $keyframes_stylesheets = array();
/**
* Current amp-keyframes CSS size.
*
* @since 1.0
* @var int
*/
private $current_keyframes_size = 0;
/**
* Spec for style[amp-keyframes] cdata.
*
* @since 1.0
* @var array
*/
private $style_keyframes_cdata_spec;
/**
* Regex for allowed font stylesheet URL.
*
* @var string
*/
private $allowed_font_src_regex;
/**
* Base URL for styles.
*
* Full URL with trailing slash.
*
* @var string
*/
private $base_url;
/**
* URL of the content directory.
*
* @var string
*/
private $content_url;
/**
* Class names used in document.
*
* @since 1.0
* @var array
*/
private $used_class_names = array();
/**
* XPath.
*
* @since 1.0
* @var DOMXPath
*/
private $xpath;
/**
* Amount of time that was spent parsing CSS.
*
* @since 1.0
* @var float
*/
private $parse_css_duration = 0.0;
/**
* AMP_Base_Sanitizer constructor.
*
* @since 0.7
*
* @param DOMDocument $dom Represents the HTML document to sanitize.
* @param array $args Args.
*/
public function __construct( DOMDocument $dom, array $args = array() ) {
parent::__construct( $dom, $args );
foreach ( AMP_Allowed_Tags_Generated::get_allowed_tag( 'style' ) as $spec_rule ) {
if ( ! isset( $spec_rule[ AMP_Rule_Spec::TAG_SPEC ]['spec_name'] ) ) {
continue;
}
if ( 'style[amp-keyframes]' === $spec_rule[ AMP_Rule_Spec::TAG_SPEC ]['spec_name'] ) {
$this->style_keyframes_cdata_spec = $spec_rule[ AMP_Rule_Spec::CDATA ];
} elseif ( 'style amp-custom' === $spec_rule[ AMP_Rule_Spec::TAG_SPEC ]['spec_name'] ) {
$this->style_custom_cdata_spec = $spec_rule[ AMP_Rule_Spec::CDATA ];
}
}
$spec_name = 'link rel=stylesheet for fonts'; // phpcs:ignore WordPress.WP.EnqueuedResources.NonEnqueuedStylesheet
foreach ( AMP_Allowed_Tags_Generated::get_allowed_tag( 'link' ) as $spec_rule ) {
if ( isset( $spec_rule[ AMP_Rule_Spec::TAG_SPEC ]['spec_name'] ) && $spec_name === $spec_rule[ AMP_Rule_Spec::TAG_SPEC ]['spec_name'] ) {
$this->allowed_font_src_regex = '@^(' . $spec_rule[ AMP_Rule_Spec::ATTR_SPEC_LIST ]['href']['value_regex'] . ')$@';
break;
}
}
$guessurl = site_url();
if ( ! $guessurl ) {
$guessurl = wp_guess_url();
}
$this->base_url = $guessurl;
$this->content_url = WP_CONTENT_URL;
$this->xpath = new DOMXPath( $dom );
}
/**
* Get list of CSS styles in HTML content of DOMDocument ($this->dom).
*
* @since 0.4
*
* @return array[] Mapping CSS selectors to array of properties, or mapping of keys starting with 'stylesheet:' with value being the stylesheet.
*/
public function get_styles() {
if ( ! $this->did_convert_elements ) {
return array();
}
return $this->styles;
}
/**
* Get stylesheets.
*
* @since 0.7
* @returns array Values are the CSS stylesheets. Keys are MD5 hashes of the stylesheets.
*/
public function get_stylesheets() {
return array_merge( $this->stylesheets, parent::get_stylesheets() );
}
/**
* Get list of all the class names used in the document.
*
* @since 1.0
* @return array Used class names.
*/
private function get_used_class_names() {
$classes = ' ';
foreach ( $this->xpath->query( '//*/@class' ) as $class_attribute ) {
$classes .= ' ' . $class_attribute->nodeValue;
}
return array_unique( array_filter( preg_split( '/\s+/', trim( $classes ) ) ) );
}
/**
* Sanitize CSS styles within the HTML contained in this instance's DOMDocument.
*
* @since 0.4
*/
public function sanitize() {
$elements = array();
// Do nothing if inline styles are allowed.
if ( ! empty( $this->args['allow_dirty_styles'] ) ) {
return;
}
$this->used_class_names = $this->get_used_class_names();
/*
* Note that xpath is used to query the DOM so that the link and style elements will be
* in document order. DOMNode::compareDocumentPosition() is not yet implemented.
*/
$xpath = $this->xpath;
$lower_case = 'translate( %s, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz" )'; // In XPath 2.0 this is lower-case().
$predicates = array(
sprintf( '( self::style and not( @amp-boilerplate ) and ( not( @type ) or %s = "text/css" ) )', sprintf( $lower_case, '@type' ) ),
sprintf( '( self::link and @href and %s = "stylesheet" )', sprintf( $lower_case, '@rel' ) ),
);
foreach ( $xpath->query( '//*[ ' . implode( ' or ', $predicates ) . ' ]' ) as $element ) {
$elements[] = $element;
}
/**
* Element.
*
* @var DOMElement $element
*/
foreach ( $elements as $element ) {
$node_name = strtolower( $element->nodeName );
if ( 'style' === $node_name ) {
$this->process_style_element( $element );
} elseif ( 'link' === $node_name ) {
$this->process_link_element( $element );
}
}
$elements = array();
foreach ( $xpath->query( '//*[ @style ]' ) as $element ) {
$elements[] = $element;
}
foreach ( $elements as $element ) {
$this->collect_inline_styles( $element );
}
$this->finalize_amp_keyframes_styles();
$this->did_convert_elements = true;
// Now make sure the amp-custom style is in the DOM and populated, if we're working with the document element.
if ( ! empty( $this->args['use_document_element'] ) ) {
if ( ! $this->amp_custom_style_element ) {
$this->amp_custom_style_element = $this->dom->createElement( 'style' );
$this->amp_custom_style_element->setAttribute( 'amp-custom', '' );
$head = $this->dom->getElementsByTagName( 'head' )->item( 0 );
if ( ! $head ) {
$head = $this->dom->createElement( 'head' );
$this->dom->documentElement->insertBefore( $head, $this->dom->documentElement->firstChild );
}
$head->appendChild( $this->amp_custom_style_element );
}
$css = implode( '', $this->get_stylesheets() );
/*
* Let the style[amp-custom] be populated with the concatenated CSS.
* !important: Updating the contents of this style element by setting textContent is not
* reliable across PHP/libxml versions, so this is why the children are removed and the
* text node is then explicitly added containing the CSS.
*/
while ( $this->amp_custom_style_element->firstChild ) {
$this->amp_custom_style_element->removeChild( $this->amp_custom_style_element->firstChild );
}
$this->amp_custom_style_element->appendChild( $this->dom->createTextNode( $css ) );
}
if ( $this->parse_css_duration > 0.0 ) {
AMP_Response_Headers::send_server_timing( 'amp_parse_css', $this->parse_css_duration, 'AMP Parse CSS' );
}
}
/**
* Generates an enqueued style's fully-qualified file path.
*
* @since 0.7
* @see WP_Styles::_css_href()
*
* @param string $src The source URL of the enqueued style.
* @return string|WP_Error Style's absolute validated filesystem path, or WP_Error when error.
*/
public function get_validated_css_file_path( $src ) {
$needs_base_url = (
! is_bool( $src )
&&
! preg_match( '|^(https?:)?//|', $src )
&&
! ( $this->content_url && 0 === strpos( $src, $this->content_url ) )
);
if ( $needs_base_url ) {
$src = $this->base_url . $src;
}
// Strip query and fragment from URL.
$src = preg_replace( ':[\?#].*$:', '', $src );
if ( ! preg_match( '/\.(css|less|scss|sass)$/i', $src ) ) {
/* translators: %s is stylesheet URL */
return new WP_Error( 'amp_css_bad_file_extension', sprintf( __( 'Skipped stylesheet which does not have recognized CSS file extension (%s).', 'amp' ), $src ) );
}
$includes_url = includes_url( '/' );
$content_url = content_url( '/' );
$admin_url = get_admin_url( null, '/' );
$css_path = null;
if ( 0 === strpos( $src, $content_url ) ) {
$css_path = WP_CONTENT_DIR . substr( $src, strlen( $content_url ) - 1 );
} elseif ( 0 === strpos( $src, $includes_url ) ) {
$css_path = ABSPATH . WPINC . substr( $src, strlen( $includes_url ) - 1 );
} elseif ( 0 === strpos( $src, $admin_url ) ) {
$css_path = ABSPATH . 'wp-admin' . substr( $src, strlen( $admin_url ) - 1 );
}
if ( ! $css_path || false !== strpos( '../', $css_path ) || 0 !== validate_file( $css_path ) || ! file_exists( $css_path ) ) {
/* translators: %s is stylesheet URL */
return new WP_Error( 'amp_css_path_not_found', sprintf( __( 'Unable to locate filesystem path for stylesheet %s.', 'amp' ), $src ) );
}
return $css_path;
}
/**
* Process style element.
*
* @param DOMElement $element Style element.
*/
private function process_style_element( DOMElement $element ) {
// @todo Any @keyframes rules could be removed from amp-custom and instead added to amp-keyframes.
$is_keyframes = $element->hasAttribute( 'amp-keyframes' );
$stylesheet = trim( $element->textContent );
$cdata_spec = $is_keyframes ? $this->style_keyframes_cdata_spec : $this->style_custom_cdata_spec;
if ( $stylesheet ) {
$stylesheet = $this->process_stylesheet( $stylesheet, $element, array(
'allowed_at_rules' => $cdata_spec['css_spec']['allowed_at_rules'],
'property_whitelist' => $cdata_spec['css_spec']['allowed_declarations'],
'validate_keyframes' => $cdata_spec['css_spec']['validate_keyframes'],
'class_selector_tree_shaking' => ! $cdata_spec['css_spec']['validate_keyframes'],
) );
}
// Remove if surpasses max size.
$length = strlen( $stylesheet );
$current_size = $is_keyframes ? $this->current_keyframes_size : $this->current_custom_size;
if ( $current_size + $length > $cdata_spec['max_bytes'] ) {
$this->remove_invalid_child( $element, array(
/* translators: %d is the number of bytes over the limit */
'message' => sprintf( __( 'Too much CSS enqueued (by %d bytes).', 'amp' ), ( $current_size + $length ) - $cdata_spec['max_bytes'] ),
) );
return;
}
$hash = md5( $stylesheet );
if ( $is_keyframes ) {
$this->keyframes_stylesheets[ $hash ] = $stylesheet;
$this->current_keyframes_size += $length;
} else {
$this->stylesheets[ $hash ] = $stylesheet;
$this->current_custom_size += $length;
}
if ( $element->hasAttribute( 'amp-custom' ) ) {
if ( ! $this->amp_custom_style_element ) {
$this->amp_custom_style_element = $element;
} else {
$element->parentNode->removeChild( $element ); // There can only be one. #highlander.
}
} else {
// Remove from DOM since we'll be adding it to amp-custom.
$element->parentNode->removeChild( $element );
}
}
/**
* Process link element.
*
* @param DOMElement $element Link element.
*/
private function process_link_element( DOMElement $element ) {
$href = $element->getAttribute( 'href' );
// Allow font URLs.
if ( $this->allowed_font_src_regex && preg_match( $this->allowed_font_src_regex, $href ) ) {
return;
}
$css_file_path = $this->get_validated_css_file_path( $href );
if ( is_wp_error( $css_file_path ) ) {
$this->remove_invalid_child( $element, array(
'message' => $css_file_path->get_error_message(),
) );
return;
}
// Load the CSS from the filesystem.
$stylesheet = file_get_contents( $css_file_path ); // phpcs:ignore -- It's a local filesystem path not a remote request.
if ( false === $stylesheet ) {
$this->remove_invalid_child( $element, array(
'message' => __( 'Unable to load stylesheet from filesystem.', 'amp' ),
) );
return;
}
// Honor the link's media attribute.
$media = $element->getAttribute( 'media' );
if ( $media && 'all' !== $media ) {
$stylesheet = sprintf( '@media %s { %s }', $media, $stylesheet );
}
$stylesheet = $this->process_stylesheet( $stylesheet, $element, array(
'allowed_at_rules' => $this->style_custom_cdata_spec['css_spec']['allowed_at_rules'],
'property_whitelist' => $this->style_custom_cdata_spec['css_spec']['allowed_declarations'],
'class_selector_tree_shaking' => true,
'stylesheet_url' => $href,
'stylesheet_path' => $css_file_path,
) );
// Skip if surpasses max size.
$length = strlen( $stylesheet );
if ( $this->current_custom_size + $length > $this->style_custom_cdata_spec['max_bytes'] ) {
$this->remove_invalid_child( $element, array(
/* translators: %d is the number of bytes over the limit */
'message' => sprintf( __( 'Too much CSS enqueued (by %d bytes).', 'amp' ), ( $this->current_custom_size + $length ) - $this->style_custom_cdata_spec['max_bytes'] ),
) );
return;
}
$hash = md5( $stylesheet );
$this->stylesheets[ $hash ] = $stylesheet;
$this->current_custom_size += $length;
// Remove now that styles have been processed.
$element->parentNode->removeChild( $element );
}
/**
* Process stylesheet.
*
* Sanitized invalid CSS properties and rules, removes rules which do not
* apply to the current document, and compresses the CSS to remove whitespace and comments.
*
* @since 1.0
*
* @param string $stylesheet Stylesheet.
* @param DOMElement|DOMAttr $node Element (link/style) or style attribute where the stylesheet came from.
* @param array $options {
* Options.
*
* @type bool $class_selector_tree_shaking Whether to perform tree shaking to delete rules that reference class names not extant in the current document.
* @type string[] $property_whitelist Exclusively-allowed properties.
* @type string[] $property_blacklist Disallowed properties.
* @type bool $convert_width_to_max_width Convert width to max-width.
* @type string $stylesheet_url Original URL for stylesheet when originating via link (or @import?).
* @type string $stylesheet_path Original filesystem path for stylesheet when originating via link (or @import?).
* }
* @return string Processed stylesheet.
*/
private function process_stylesheet( $stylesheet, $node, $options = array() ) {
$should_tree_shake = ! empty( $options['class_selector_tree_shaking'] );
unset( $options['class_selector_tree_shaking'] );
$cache_key = md5( $stylesheet . serialize( $options ) ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_serialize
$cache_group = 'amp-parsed-stylesheet-v1';
if ( wp_using_ext_object_cache() ) {
$parsed = wp_cache_get( $cache_key, $cache_group );
} else {
$parsed = get_transient( $cache_key . $cache_group );
}
if ( ! $parsed || ! isset( $parsed['stylesheet'] ) || ! is_array( $parsed['stylesheet'] ) ) {
$parsed = $this->parse_stylesheet( $stylesheet, $options );
if ( wp_using_ext_object_cache() ) {
wp_cache_set( $cache_key, $parsed, $cache_group );
} else {
// The expiration is to ensure transient doesn't stick around forever since no LRU flushing like with external object cache.
set_transient( $cache_key . $cache_group, $parsed, MONTH_IN_SECONDS );
}
}
if ( ! empty( $this->args['validation_error_callback'] ) && ! empty( $parsed['validation_errors'] ) ) {
foreach ( $parsed['validation_errors'] as $validation_error ) {
call_user_func( $this->args['validation_error_callback'], array_merge( $validation_error, compact( 'node' ) ) );
}
}
$stylesheet = '';
foreach ( $parsed['stylesheet'] as $stylesheet_part ) {
if ( is_array( $stylesheet_part ) ) {
list( $selectors_parsed, $declaration_block ) = $stylesheet_part;
if ( $should_tree_shake ) {
$selectors = array();
foreach ( $selectors_parsed as $selector => $class_names ) {
if ( 0 === count( array_diff( $class_names, $this->used_class_names ) ) ) { // If all class names are used in the doc.
$selectors[] = $selector;
}
}
} else {
$selectors = array_keys( $selectors_parsed );
}
if ( ! empty( $selectors ) ) {
$stylesheet .= implode( ',', $selectors ) . $declaration_block;
}
} else {
$stylesheet .= $stylesheet_part;
}
}
return $stylesheet;
}
/**
* Parse stylesheet.
*
* @since 1.0
*
* @param string $stylesheet_string Stylesheet.
* @param array $options Options. See definition in \AMP_Style_Sanitizer::process_stylesheet().
* @return array {
* Parsed stylesheet.
*
* @type array $stylesheet Stylesheet parts, where arrays are tuples for declaration blocks.
* @type array $validation_errors Validation errors.
* }
*/
private function parse_stylesheet( $stylesheet_string, $options = array() ) {
$start_time = microtime( true );
$options = array_merge(
array(
'allowed_at_rules' => array(),
'convert_width_to_max_width' => false,
'property_blacklist' => array(
// See <https://www.ampproject.org/docs/design/responsive/style_pages#disallowed-styles>.
'behavior',
'-moz-binding',
),
'property_whitelist' => array(),
'validate_keyframes' => false,
'stylesheet_url' => null,
'stylesheet_path' => null,
),
$options
);
$stylesheet = array();
$validation_errors = array();
try {
$parser_settings = Sabberworm\CSS\Settings::create()->withMultibyteSupport( false );
$css_parser = new Sabberworm\CSS\Parser( $stylesheet_string, $parser_settings );
$css_document = $css_parser->parse();
if ( ! empty( $options['stylesheet_url'] ) ) {
$this->real_path_urls(
array_filter(
$css_document->getAllValues(),
function ( $value ) {
return $value instanceof URL;
}
),
$options['stylesheet_url']
);
}
$validation_errors = $this->process_css_list( $css_document, $options );
$output_format = Sabberworm\CSS\OutputFormat::createCompact();
$before_declaration_block = '/*AMP_WP_BEFORE_DECLARATION_BLOCK*/';
$between_selectors = '/*AMP_WP_BETWEEN_SELECTORS*/';
$after_declaration_block_selectors = '/*AMP_WP_BEFORE_DECLARATION_SELECTORS*/';
$after_declaration_block = '/*AMP_WP_AFTER_DECLARATION*/';
$output_format->set( 'BeforeDeclarationBlock', $before_declaration_block );
$output_format->set( 'SpaceBeforeSelectorSeparator', $between_selectors );
$output_format->set( 'AfterDeclarationBlockSelectors', $after_declaration_block_selectors );
$output_format->set( 'AfterDeclarationBlock', $after_declaration_block );
$stylesheet_string = $css_document->render( $output_format );
$pattern = '#';
$pattern .= '(' . preg_quote( $before_declaration_block, '#' ) . ')';
$pattern .= '(.+?)';
$pattern .= preg_quote( $after_declaration_block_selectors, '#' );
$pattern .= '(.+?)';
$pattern .= preg_quote( $after_declaration_block, '#' );
$pattern .= '#s';
$split_stylesheet = preg_split( $pattern, $stylesheet_string, -1, PREG_SPLIT_DELIM_CAPTURE );
$length = count( $split_stylesheet );
for ( $i = 0; $i < $length; $i++ ) {
if ( $before_declaration_block === $split_stylesheet[ $i ] ) {
$selectors = explode( $between_selectors . ',', $split_stylesheet[ ++$i ] );
$declaration = $split_stylesheet[ ++$i ];
$selectors_parsed = array();
foreach ( $selectors as $selector ) {
$classes = array();
// Remove :not() to eliminate false negatives, such as with `body:not(.title-tagline-hidden) .site-branding-text`.
$reduced_selector = preg_replace( '/:not\(.+?\)/', '', $selector );
// Remove attribute selectors to eliminate false negative, such as with `.social-navigation a[href*="example.com"]:before`.
$reduced_selector = preg_replace( '/\[\w.*?\]/', '', $reduced_selector );
if ( preg_match_all( '/(?<=\.)([a-zA-Z0-9_-]+)/', $reduced_selector, $matches ) ) {
$classes = $matches[0];
}
$selectors_parsed[ $selector ] = $classes;
}
$stylesheet[] = array(
$selectors_parsed,
$declaration,
);
} else {
$stylesheet[] = $split_stylesheet[ $i ];
}
}
} catch ( Exception $exception ) {
$validation_errors[] = array(
'code' => 'css_parse_error',
'message' => $exception->getMessage(),
);
}
$this->parse_css_duration += ( microtime( true ) - $start_time );
return compact( 'stylesheet', 'validation_errors' );
}
/**
* Process CSS list.
*
* @since 1.0
*
* @param CSSList $css_list CSS List.
* @param array $options Options.
* @return array Validation errors.
*/
private function process_css_list( CSSList $css_list, $options ) {
$validation_errors = array();
foreach ( $css_list->getContents() as $css_item ) {
if ( $css_item instanceof DeclarationBlock && empty( $options['validate_keyframes'] ) ) {
$validation_errors = array_merge(
$validation_errors,
$this->process_css_declaration_block( $css_item, $css_list, $options )
);
} elseif ( $css_item instanceof AtRuleBlockList ) {
if ( in_array( $css_item->atRuleName(), $options['allowed_at_rules'], true ) ) {
$validation_errors = array_merge(
$validation_errors,
$this->process_css_list( $css_item, $options )
);
} else {
$validation_errors[] = array(
'code' => 'illegal_css_at_rule',
/* translators: %s is the CSS at-rule name. */
'message' => sprintf( __( 'CSS @%s rules are currently disallowed.', 'amp' ), $css_item->atRuleName() ),
);
$css_list->remove( $css_item );
}
} elseif ( $css_item instanceof Import ) {
$validation_errors[] = array(
'code' => 'illegal_css_import_rule',
'message' => __( 'CSS @import is currently disallowed.', 'amp' ),
);
$css_list->remove( $css_item );
} elseif ( $css_item instanceof AtRuleSet ) {
if ( in_array( $css_item->atRuleName(), $options['allowed_at_rules'], true ) ) {
$validation_errors = array_merge(
$validation_errors,
$this->process_css_declaration_block( $css_item, $css_list, $options )
);
} else {
$validation_errors[] = array(
'code' => 'illegal_css_at_rule',
/* translators: %s is the CSS at-rule name. */
'message' => sprintf( __( 'CSS @%s rules are currently disallowed.', 'amp' ), $css_item->atRuleName() ),
);
$css_list->remove( $css_item );
}
} elseif ( $css_item instanceof KeyFrame ) {
if ( in_array( 'keyframes', $options['allowed_at_rules'], true ) ) {
$validation_errors = array_merge(
$validation_errors,
$this->process_css_keyframes( $css_item, $options )
);
} else {
$validation_errors[] = array(
'code' => 'illegal_css_at_rule',
/* translators: %s is the CSS at-rule name. */
'message' => sprintf( __( 'CSS @%s rules are currently disallowed.', 'amp' ), $css_item->atRuleName() ),
);
}
} elseif ( $css_item instanceof AtRule ) {
$validation_errors[] = array(
'code' => 'illegal_css_at_rule',
/* translators: %s is the CSS at-rule name. */
'message' => sprintf( __( 'CSS @%s rules are currently disallowed.', 'amp' ), $css_item->atRuleName() ),
);
$css_list->remove( $css_item );
} else {
$validation_errors[] = array(
'code' => 'unrecognized_css',
'message' => __( 'Unrecognized CSS removed.', 'amp' ),
);
$css_list->remove( $css_item );
}
}
return $validation_errors;
}
/**
* Convert URLs in to non-relative real-paths.
*
* @param URL[] $urls URLs.
* @param string $stylesheet_url Stylesheet URL.
*/
private function real_path_urls( $urls, $stylesheet_url ) {
$base_url = preg_replace( ':[^/]+(\?.*)?(#.*)?$:', '', $stylesheet_url );
if ( empty( $base_url ) ) {
return;
}
foreach ( $urls as $url ) {
$url_string = $url->getURL()->getString();
if ( 'data:' === substr( $url_string, 0, 5 ) ) {
continue;
}
$parsed_url = wp_parse_url( $url_string );
if ( ! empty( $parsed_url['host'] ) || empty( $parsed_url['path'] ) || '/' === substr( $parsed_url['path'], 0, 1 ) ) {
continue;
}
$relative_url = preg_replace( '#^\./#', '', $url->getURL()->getString() );
$real_url = $base_url . $relative_url;
do {
$real_url = preg_replace( '#[^/]+/../#', '', $real_url, -1, $count );
} while ( 0 !== $count );
$url->getURL()->setString( $real_url );
}
}
/**
* Process CSS rule set.
*
* @since 1.0
* @link https://www.ampproject.org/docs/design/responsive/style_pages#disallowed-styles
* @link https://www.ampproject.org/docs/design/responsive/style_pages#restricted-styles
*
* @param RuleSet $ruleset Ruleset.
* @param CSSList $css_list CSS List.
* @param array $options Options.
*
* @return array Validation errors.
*/
private function process_css_declaration_block( RuleSet $ruleset, CSSList $css_list, $options ) {
$validation_errors = array();
// Remove disallowed properties.
if ( ! empty( $options['property_whitelist'] ) ) {
$properties = $ruleset->getRules();
foreach ( $properties as $property ) {
$vendorless_property_name = preg_replace( '/^-\w+-/', '', $property->getRule() );
if ( ! in_array( $vendorless_property_name, $options['property_whitelist'], true ) ) {
$validation_errors[] = array(
'code' => 'illegal_css_property',
'property_name' => $property->getRule(),
'property_value' => $property->getValue(),
);
$ruleset->removeRule( $property->getRule() );
}
}
} else {
foreach ( $options['property_blacklist'] as $illegal_property_name ) {
$properties = $ruleset->getRules( $illegal_property_name );
foreach ( $properties as $property ) {
$validation_errors[] = array(
'code' => 'illegal_css_property',
'property_name' => $property->getRule(),
'property_value' => $property->getValue(),
);
$ruleset->removeRule( $property->getRule() );
}
}
}
if ( $ruleset instanceof AtRuleSet && 'font-face' === $ruleset->atRuleName() ) {
$this->process_font_face_at_rule( $ruleset );
}
$validation_errors = array_merge(
$validation_errors,
$this->transform_important_qualifiers( $ruleset, $css_list )
);
// Convert width to max-width when requested. See <https://github.com/Automattic/amp-wp/issues/494>.
if ( $options['convert_width_to_max_width'] ) {
$properties = $ruleset->getRules( 'width' );
foreach ( $properties as $property ) {
$width_property = new Rule( 'max-width' );
$width_property->setValue( $property->getValue() );
$ruleset->removeRule( $property );
$ruleset->addRule( $width_property, $property );
}
}
// Remove the ruleset if it is now empty.
if ( 0 === count( $ruleset->getRules() ) ) {
$css_list->remove( $ruleset );
}
// @todo Delete rules with selectors for -amphtml- class and i-amphtml- tags.
return $validation_errors;
}
/**
* Process @font-face by making src URLs non-relative and converting data: URLs into (assumed) file URLs.
*
* @since 1.0
*
* @param AtRuleSet $ruleset Ruleset for @font-face.
*/
private function process_font_face_at_rule( AtRuleSet $ruleset ) {
$src_properties = $ruleset->getRules( 'src' );
if ( empty( $src_properties ) ) {
return;
}
foreach ( $src_properties as $src_property ) {
$value = $src_property->getValue();
if ( ! ( $value instanceof RuleValueList ) ) {
continue;
}
/*
* The CSS Parser parses a src such as:
*
* url(data:application/font-woff;...) format('woff'),
* url('Genericons.ttf') format('truetype'),
* url('Genericons.svg#genericonsregular') format('svg')
*
* As a list of components consisting of:
*
* URL,
* RuleValueList( CSSFunction, URL ),
* RuleValueList( CSSFunction, URL ),
* CSSFunction
*
* Clearly the components here are not logically grouped. So the first step is to fix the order.
*/
$sources = array();
foreach ( $value->getListComponents() as $component ) {
if ( $component instanceof RuleValueList ) {
$subcomponents = $component->getListComponents();
$subcomponent = array_shift( $subcomponents );
if ( $subcomponent ) {
if ( empty( $sources ) ) {
$sources[] = array( $subcomponent );
} else {
$sources[ count( $sources ) - 1 ][] = $subcomponent;
}
}
foreach ( $subcomponents as $subcomponent ) {
$sources[] = array( $subcomponent );
}
} else {
if ( empty( $sources ) ) {
$sources[] = array( $component );
} else {
$sources[ count( $sources ) - 1 ][] = $component;
}
}
}
/**
* Source URL lists.
*
* @var URL[] $source_file_urls
* @var URL[] $source_data_urls
*/
$source_file_urls = array();
$source_data_urls = array();
foreach ( $sources as $i => $source ) {
if ( $source[0] instanceof URL ) {
if ( 'data:' === substr( $source[0]->getURL()->getString(), 0, 5 ) ) {
$source_data_urls[ $i ] = $source[0];
} else {
$source_file_urls[ $i ] = $source[0];
}
}
}
// Convert data: URLs into regular URLs, assuming there will be a file present (e.g. woff fonts in core themes).
if ( empty( $source_file_urls ) ) {
continue;
}
$source_file_url = current( $source_file_urls );
foreach ( $source_data_urls as $i => $data_url ) {
$mime_type = strtok( substr( $data_url->getURL()->getString(), 5 ), ';' );
if ( ! $mime_type ) {
continue;
}
$extension = preg_replace( ':.+/(.+-)?:', '', $mime_type );
$guessed_url = preg_replace(
':(?<=\.)\w+(\?.*)?(#.*)?$:', // Match the file extension in the URL.
$extension,
$source_file_url->getURL()->getString(),
1,
$count
);
if ( $count ) {
$data_url->getURL()->setString( $guessed_url );
}
}
}
}
/**
* Process CSS keyframes.
*
* @since 1.0
* @link https://www.ampproject.org/docs/design/responsive/style_pages#restricted-styles.
* @link https://github.com/ampproject/amphtml/blob/b685a0780a7f59313666225478b2b79b463bcd0b/validator/validator-main.protoascii#L1002-L1043
* @todo Tree shaking could be extended to keyframes, to omit a keyframe if it is not referenced by any rule.
*
* @param KeyFrame $css_list Ruleset.
* @param array $options Options.
* @return array Validation errors.
*/
private function process_css_keyframes( KeyFrame $css_list, $options ) {
$validation_errors = array();
if ( ! empty( $options['property_whitelist'] ) ) {
foreach ( $css_list->getContents() as $rules ) {
if ( ! ( $rules instanceof DeclarationBlock ) ) {
$validation_errors[] = array(
'code' => 'unrecognized_css',
'message' => __( 'Unrecognized CSS removed.', 'amp' ),
);
$css_list->remove( $rules );
continue;
}
$validation_errors = array_merge(
$validation_errors,
$this->transform_important_qualifiers( $rules, $css_list )
);
$properties = $rules->getRules();
foreach ( $properties as $property ) {
$vendorless_property_name = preg_replace( '/^-\w+-/', '', $property->getRule() );
if ( ! in_array( $vendorless_property_name, $options['property_whitelist'], true ) ) {
$validation_errors[] = array(
'code' => 'illegal_css_property',
'property_name' => $property->getRule(),
'property_value' => $property->getValue(),
);
$rules->removeRule( $property->getRule() );
}
}
}