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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\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;
use \Sabberworm\CSS\CSSList\Document;
/**
* Class AMP_Style_Sanitizer
*
* Collects inline styles and outputs them in the amp-custom stylesheet.
*/
class AMP_Style_Sanitizer extends AMP_Base_Sanitizer {
/**
* Error code for tree shaking.
*
* @var string
*/
const TREE_SHAKING_ERROR_CODE = 'removed_unused_css_rules';
/**
* Error code for illegal at-rule.
*
* @var string
*/
const ILLEGAL_AT_RULE_ERROR_CODE = 'illegal_css_at_rule';
/**
* Inline style selector's specificity multiplier, i.e. used to generate the number of ':not(#_)' placeholders.
*
* @var int
*/
const INLINE_SPECIFICITY_MULTIPLIER = 5; // @todo The correctness of using "5" should be validated.
/**
* Array of flags used to control sanitization.
*
* @var array {
* @type string $remove_unused_rules Enum 'never', 'sometimes' (default), 'always'. If total CSS is greater than max_bytes, whether to strip selectors (and then empty rules) when they are not found to be used in doc. A validation error will be emitted when stripping happens since it is not completely safe in the case of dynamic content.
* @type string[] $dynamic_element_selectors Selectors for elements (or their ancestors) which contain dynamic content; selectors containing these will not be filtered.
* @type bool $use_document_element Whether the root of the document should be used rather than the body.
* @type bool $require_https_src Require HTTPS URLs.
* @type bool $allow_dirty_styles Allow dirty styles. This short-circuits the sanitize logic; it is used primarily in Customizer preview.
* @type callable $validation_error_callback Function to call when a validation error is encountered.
* @type bool $should_locate_sources Whether to locate the sources when reporting validation errors.
* @type string $parsed_cache_variant Additional value by which to vary parsed cache.
* @type bool $accept_tree_shaking Whether to accept tree-shaking by default and bypass a validation error.
* }
*/
protected $args;
/**
* Default args.
*
* @var array
*/
protected $DEFAULT_ARGS = array(
'remove_unused_rules' => 'sometimes',
'dynamic_element_selectors' => array(
'amp-list',
'amp-live-list',
'[submit-error]',
'[submit-success]',
),
'should_locate_sources' => false,
'parsed_cache_variant' => null,
'accept_tree_shaking' => false,
);
/**
* Stylesheets.
*
* Values are the CSS stylesheets. Keys are MD5 hashes of the stylesheets,
*
* @since 0.7
* @var string[]
*/
private $stylesheets = array();
/**
* List of stylesheet parts prior to selector/rule removal (tree shaking).
*
* Keys are MD5 hashes of stylesheets.
*
* @since 1.0
* @var array[] {
* @type array $stylesheet Array of stylesheet chunked, with declaration blocks being represented as arrays.
* @type DOMElement|DOMAttr $node Origin for styles.
* @type array $sources Sources for the node.
* @type bool $keyframes Whether an amp-keyframes.
* }
*/
private $pending_stylesheets = array();
/**
* 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;
/**
* 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();
/**
* Tag names used in document.
*
* @since 1.0
* @var array
*/
private $used_tag_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;
/**
* THe HEAD element.
*
* @var DOMElement
*/
private $head;
/**
* Current node being processed.
*
* @var DOMElement|DOMAttr
*/
private $current_node;
/**
* Current sources for a given node.
*
* @var array
*/
private $current_sources;
/**
* Log of the stylesheet URLs that have been imported to guard against infinite loops.
*
* @var array
*/
private $processed_imported_stylesheet_urls = array();
/**
* List of font stylesheets that were @import'ed which should have been <link>'ed to instead.
*
* These font URLs will be cached with the parsed CSS and then converted into stylesheet links.
*
* @var array
*/
private $imported_font_urls = array();
/**
* Mapping of HTML element selectors to AMP selector elements.
*
* @var array
*/
private $selector_mappings = array();
/**
* Get error codes that can be raised during parsing of CSS.
*
* This is used to determine which validation errors should be taken into account
* when determining which validation errors should vary the parse cache.
*
* @return array
*/
public static function get_css_parser_validation_error_codes() {
return array(
'css_parse_error',
'excessive_css',
self::ILLEGAL_AT_RULE_ERROR_CODE,
'illegal_css_important',
'illegal_css_property',
self::TREE_SHAKING_ERROR_CODE,
'unrecognized_css',
'disallowed_file_extension',
'file_path_not_found',
);
}
/**
* 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
* @deprecated As of 1.0, use get_stylesheets().
*
* @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() {
return array();
}
/**
* Get stylesheets.
*
* @since 0.7
* @returns array Values are the CSS stylesheets. Keys are MD5 hashes of the stylesheets.
*/
public function get_stylesheets() {
return $this->stylesheets;
}
/**
* Get list of all the class names used in the document, including those used in [class] attributes.
*
* @since 1.0
* @return array Used class names.
*/
private function get_used_class_names() {
if ( empty( $this->used_class_names ) ) {
$classes = ' ';
foreach ( $this->xpath->query( '//*/@class' ) as $class_attribute ) {
$classes .= ' ' . $class_attribute->nodeValue;
}
// Find all [class] attributes and capture the contents of any single- or double-quoted strings.
foreach ( $this->xpath->query( '//*/@' . AMP_DOM_Utils::get_amp_bind_placeholder_prefix() . 'class' ) as $bound_class_attribute ) {
if ( preg_match_all( '/([\'"])([^\1]*?)\1/', $bound_class_attribute->nodeValue, $matches ) ) {
$classes .= ' ' . implode( ' ', $matches[2] );
}
}
$this->used_class_names = array_unique( array_filter( preg_split( '/\s+/', trim( $classes ) ) ) );
}
return $this->used_class_names;
}
/**
* Get list of all the tag names used in the document.
*
* @since 1.0
* @return array Used tag names.
*/
private function get_used_tag_names() {
if ( empty( $this->used_tag_names ) ) {
$used_tag_names = array();
foreach ( $this->dom->getElementsByTagName( '*' ) as $el ) {
$used_tag_names[ $el->tagName ] = true;
}
$this->used_tag_names = array_keys( $used_tag_names );
}
return $this->used_tag_names;
}
/**
* Run logic before any sanitizers are run.
*
* After the sanitizers are instantiated but before calling sanitize on each of them, this
* method is called with list of all the instantiated sanitizers.
*
* @param AMP_Base_Sanitizer[] $sanitizers Sanitizers.
*/
public function init( $sanitizers ) {
parent::init( $sanitizers );
foreach ( $sanitizers as $sanitizer ) {
foreach ( $sanitizer->get_selector_conversion_mapping() as $html_selectors => $amp_selectors ) {
if ( ! isset( $this->selector_mappings[ $html_selectors ] ) ) {
$this->selector_mappings[ $html_selectors ] = $amp_selectors;
} else {
$this->selector_mappings[ $html_selectors ] = array_unique(
array_merge( $this->selector_mappings[ $html_selectors ], $amp_selectors )
);
}
// Prevent selectors like `amp-img img` getting deleted since `img` does not occur in the DOM.
$this->args['dynamic_element_selectors'] = array_merge(
$this->args['dynamic_element_selectors'],
$this->selector_mappings[ $html_selectors ]
);
}
}
}
/**
* 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->head = $this->dom->getElementsByTagName( 'head' )->item( 0 );
if ( ! $this->head ) {
$this->head = $this->dom->createElement( 'head' );
$this->dom->documentElement->insertBefore( $this->head, $this->dom->documentElement->firstChild );
}
$this->parse_css_duration = 0.0;
/*
* 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;
}
// If 'width' attribute is present for 'col' tag, convert to proper CSS rule.
foreach ( $this->dom->getElementsByTagName( 'col' ) as $col ) {
/**
* Col element.
*
* @var DOMElement $col
*/
$width_attr = $col->getAttribute( 'width' );
if ( ! empty( $width_attr ) && ( false === strpos( $width_attr, '*' ) ) ) {
$width_style = 'width: ' . $width_attr;
if ( is_numeric( $width_attr ) ) {
$width_style .= 'px';
}
if ( $col->hasAttribute( 'style' ) ) {
$col->setAttribute( 'style', $width_style . ';' . $col->getAttribute( 'style' ) );
} else {
$col->setAttribute( 'style', $width_style );
}
$col->removeAttribute( 'width' );
}
}
/**
* 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_styles();
$this->did_convert_elements = true;
if ( $this->parse_css_duration > 0.0 ) {
AMP_HTTP::send_server_timing( 'amp_parse_css', $this->parse_css_duration, 'AMP Parse CSS' );
}
}
/**
* Generate a URL's fully-qualified file path.
*
* @since 0.7
* @see WP_Styles::_css_href()
*
* @param string $url The file URL.
* @param string[] $allowed_extensions Allowed file extensions for local files.
* @return string|WP_Error Style's absolute validated filesystem path, or WP_Error when error.
*/
public function get_validated_url_file_path( $url, $allowed_extensions = array() ) {
$needs_base_url = (
! is_bool( $url )
&&
! preg_match( '|^(https?:)?//|', $url )
&&
! ( $this->content_url && 0 === strpos( $url, $this->content_url ) )
);
if ( $needs_base_url ) {
$url = $this->base_url . $url;
}
$remove_url_scheme = function( $schemed_url ) {
return preg_replace( '#^\w+:(?=//)#', '', $schemed_url );
};
// Strip URL scheme, query, and fragment.
$url = $remove_url_scheme( preg_replace( ':[\?#].*$:', '', $url ) );
$includes_url = $remove_url_scheme( includes_url( '/' ) );
$content_url = $remove_url_scheme( content_url( '/' ) );
$admin_url = $remove_url_scheme( get_admin_url( null, '/' ) );
$allowed_hosts = array(
wp_parse_url( $includes_url, PHP_URL_HOST ),
wp_parse_url( $content_url, PHP_URL_HOST ),
wp_parse_url( $admin_url, PHP_URL_HOST ),
);
$url_host = wp_parse_url( $url, PHP_URL_HOST );
// Validate file extensions.
if ( ! empty( $allowed_extensions ) ) {
$pattern = sprintf( '/\.(%s)$/i', implode( '|', $allowed_extensions ) );
if ( ! preg_match( $pattern, $url ) ) {
/* translators: %s: the file URL. */
return new WP_Error( 'disallowed_file_extension', sprintf( __( 'File does not have an allowed file extension for filesystem access (%s).', 'amp' ), $url ) );
}
}
if ( ! in_array( $url_host, $allowed_hosts, true ) ) {
/* translators: %s: the file URL */
return new WP_Error( 'external_file_url', sprintf( __( 'URL is located on an external domain: %s.', 'amp' ), $url_host ) );
}
$base_path = null;
$file_path = null;
if ( 0 === strpos( $url, $content_url ) ) {
$base_path = WP_CONTENT_DIR;
$file_path = substr( $url, strlen( $content_url ) - 1 );
} elseif ( 0 === strpos( $url, $includes_url ) ) {
$base_path = ABSPATH . WPINC;
$file_path = substr( $url, strlen( $includes_url ) - 1 );
} elseif ( 0 === strpos( $url, $admin_url ) ) {
$base_path = ABSPATH . 'wp-admin';
$file_path = substr( $url, strlen( $admin_url ) - 1 );
}
if ( ! $file_path || false !== strpos( $file_path, '../' ) || false !== strpos( $file_path, '..\\' ) ) {
/* translators: %s: the file URL. */
return new WP_Error( 'file_path_not_allowed', sprintf( __( 'Disallowed URL filesystem path for %s.', 'amp' ), $url ) );
}
if ( ! file_exists( $base_path . $file_path ) ) {
/* translators: %s: the file URL. */
return new WP_Error( 'file_path_not_found', sprintf( __( 'Unable to locate filesystem path for %s.', 'amp' ), $url ) );
}
return $base_path . $file_path;
}
/**
* Set the current node (and its sources when required).
*
* @since 1.0
* @param DOMElement|DOMAttr|null $node Current node, or null to reset.
*/
private function set_current_node( $node ) {
if ( $this->current_node === $node ) {
return;
}
$this->current_node = $node;
if ( empty( $node ) ) {
$this->current_sources = null;
} elseif ( ! empty( $this->args['should_locate_sources'] ) ) {
$this->current_sources = AMP_Validation_Manager::locate_sources( $node );
}
}
/**
* Process style element.
*
* @param DOMElement $element Style element.
*/
private function process_style_element( DOMElement $element ) {
$this->set_current_node( $element ); // And sources when needing to be located.
// @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;
// Honor the style's media attribute.
$media = $element->getAttribute( 'media' );
if ( $media && 'all' !== $media ) {
$stylesheet = sprintf( '@media %s { %s }', $media, $stylesheet );
}
$processed = $this->process_stylesheet( $stylesheet, array(
'allowed_at_rules' => $cdata_spec['css_spec']['allowed_at_rules'],
'property_whitelist' => $cdata_spec['css_spec']['declaration'],
'validate_keyframes' => $cdata_spec['css_spec']['validate_keyframes'],
) );
$this->pending_stylesheets[] = array_merge(
array(
'keyframes' => $is_keyframes,
'node' => $element,
'sources' => $this->current_sources,
),
wp_array_slice_assoc( $processed, array( 'stylesheet', 'imported_font_urls' ) )
);
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 );
}
$this->set_current_node( null );
}
/**
* Process link element.
*
* @param DOMElement $element Link element.
*/
private function process_link_element( DOMElement $element ) {
$href = $element->getAttribute( 'href' );
// Allow font URLs, including protocol-less URLs and recognized URLs that use HTTP instead of HTTPS.
$normalized_url = preg_replace( '#^(http:)?(?=//)#', 'https:', $href );
if ( $this->allowed_font_src_regex && preg_match( $this->allowed_font_src_regex, $normalized_url ) ) {
if ( $href !== $normalized_url ) {
$element->setAttribute( 'href', $normalized_url );
}
/*
* Make sure rel=preconnect link is present for Google Fonts stylesheet.
* Note that core themes normally do this already, per <https://core.trac.wordpress.org/ticket/37171>.
* But not always, per <https://core.trac.wordpress.org/ticket/44668>.
* This also ensures that other themes will get the preconnect link when
* they don't implement the resource hint.
*/
$needs_preconnect_link = (
'https://fonts.googleapis.com/' === substr( $normalized_url, 0, 29 )
&&
0 === $this->xpath->query( '//link[ @rel = "preconnect" and @crossorigin and starts-with( @href, "https://fonts.gstatic.com" ) ]', $this->head )->length
);
if ( $needs_preconnect_link ) {
$link = AMP_DOM_Utils::create_node( $this->dom, 'link', array(
'rel' => 'preconnect',
'href' => 'https://fonts.gstatic.com/',
'crossorigin' => '',
) );
$this->head->insertBefore( $link ); // Note that \AMP_Theme_Support::ensure_required_markup() will put this in the optimal order.
}
return;
}
$css_file_path = $this->get_validated_url_file_path( $href, array( 'css', 'less', 'scss', 'sass' ) );
if ( is_wp_error( $css_file_path ) && ( 'disallowed_file_extension' === $css_file_path->get_error_code() || 'external_file_url' === $css_file_path->get_error_code() ) ) {
$contents = $this->fetch_external_stylesheet( $normalized_url );
if ( is_wp_error( $contents ) ) {
$this->remove_invalid_child( $element, array(
'code' => $css_file_path->get_error_code(),
'message' => $css_file_path->get_error_message(),
'type' => AMP_Validation_Error_Taxonomy::CSS_ERROR_TYPE,
) );
return;
} else {
$stylesheet = $contents;
}
} elseif ( is_wp_error( $css_file_path ) ) {
$this->remove_invalid_child( $element, array(
'code' => $css_file_path->get_error_code(),
'message' => $css_file_path->get_error_message(),
'type' => AMP_Validation_Error_Taxonomy::CSS_ERROR_TYPE,
) );
return;
} else {
$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(
'code' => 'stylesheet_file_missing',
'type' => AMP_Validation_Error_Taxonomy::CSS_ERROR_TYPE,
) );
return;
}
// Honor the link's media attribute.
$media = $element->getAttribute( 'media' );
if ( $media && 'all' !== $media ) {
$stylesheet = sprintf( '@media %s { %s }', $media, $stylesheet );
}
$this->set_current_node( $element ); // And sources when needing to be located.
$processed = $this->process_stylesheet( $stylesheet, array(
'allowed_at_rules' => $this->style_custom_cdata_spec['css_spec']['allowed_at_rules'],
'property_whitelist' => $this->style_custom_cdata_spec['css_spec']['declaration'],
'stylesheet_url' => $href,
'stylesheet_path' => $css_file_path,
) );
$this->pending_stylesheets[] = array_merge(
array(
'keyframes' => false,
'node' => $element,
'sources' => $this->current_sources, // Needed because node is removed below.
),
wp_array_slice_assoc( $processed, array( 'stylesheet', 'imported_font_urls' ) )
);
// Remove now that styles have been processed.
$element->parentNode->removeChild( $element );
$this->set_current_node( null );
}
/**
* Fetch external stylesheet.
*
* @param string $url External stylesheet URL.
* @return string|WP_Error Stylesheet contents or WP_Error.
*/
private function fetch_external_stylesheet( $url ) {
$cache_key = md5( $url );
$contents = get_transient( $cache_key );
if ( false === $contents ) {
$r = wp_remote_get( $url );
if ( 200 !== wp_remote_retrieve_response_code( $r ) ) {
$contents = new WP_Error(
wp_remote_retrieve_response_code( $r ),
wp_remote_retrieve_response_message( $r )
);
} else {
$contents = wp_remote_retrieve_body( $r );
}
set_transient( $cache_key, $contents, MONTH_IN_SECONDS );
}
return $contents;
}
/**
* 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 array $options {
* Options.
*
* @type string[] $property_whitelist Exclusively-allowed properties.
* @type string[] $property_blacklist Disallowed properties.
* @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.
* @type array $allowed_at_rules Allowed @-rules.
* @type bool $validate_keyframes Whether keyframes should be validated.
* }
* @return array {
* Processed stylesheet.
*
* @type array $stylesheet Stylesheet parts, where arrays are tuples for declaration blocks.
* @type array $validation_results Validation results, array containing arrays with error and sanitized keys.
* @type array $imported_font_urls Imported font stylesheet URLs.
* }
*/
private function process_stylesheet( $stylesheet, $options = array() ) {
$parsed = null;
$cache_key = null;
$cache_group = 'amp-parsed-stylesheet-v12'; // This should be bumped whenever the PHP-CSS-Parser is updated.
$cache_impacting_options = array_merge(
wp_array_slice_assoc(
$options,
array( 'property_whitelist', 'property_blacklist', 'stylesheet_url', 'allowed_at_rules' )
),
wp_array_slice_assoc(
$this->args,
array( 'should_locate_sources', 'parsed_cache_variant' )
),
array(
'language' => get_bloginfo( 'language' ), // Used to tree-shake html[lang] selectors.
)
);
$cache_key = md5( $stylesheet . wp_json_encode( $cache_impacting_options ) );
if ( wp_using_ext_object_cache() ) {
$parsed = wp_cache_get( $cache_key, $cache_group );
} else {
$parsed = get_transient( $cache_key . $cache_group );
}
/*
* Make sure that the parsed stylesheet was cached with current sanitizations.
* The should_sanitize_validation_error method prevents duplicates from being reported.
*/
if ( ! empty( $parsed['validation_results'] ) ) {
foreach ( $parsed['validation_results'] as $validation_result ) {
$sanitized = $this->should_sanitize_validation_error( $validation_result['error'] );
if ( $sanitized !== $validation_result['sanitized'] ) {
$parsed = null; // Change to sanitization of validation error detected, so cache cannot be used.
break;
}
}
}
if ( ! $parsed || ! isset( $parsed['stylesheet'] ) || ! is_array( $parsed['stylesheet'] ) ) {
$parsed = $this->prepare_stylesheet( $stylesheet, $options );
/*
* When an object cache is not available, we cache with an expiration to prevent the options table from
* getting filled infinitely. On the other hand, if an external object cache is available then we don't
* set an expiration because it should implement LRU cache expulsion policy.
*/
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 );
}
}
return $parsed;
}
/**
* Parse imported stylesheet.
*
* @param Import $item Import object.
* @param CSSList $css_list CSS List.
* @param array $options {
* Options.
*
* @type string $stylesheet_url Original URL for stylesheet when originating via link or @import.
* }
* @return array Validation results.
*/
private function parse_import_stylesheet( Import $item, CSSList $css_list, $options ) {
$results = array();
$at_rule_args = $item->atRuleArgs();
$location = array_shift( $at_rule_args );
$media_query = array_shift( $at_rule_args );
if ( isset( $options['stylesheet_url'] ) ) {
$this->real_path_urls( array( $location ), $options['stylesheet_url'] );
}
$import_stylesheet_url = $location->getURL()->getString();
// Prevent importing something that has already been imported, and avoid infinite recursion.
if ( isset( $this->processed_imported_stylesheet_urls[ $import_stylesheet_url ] ) ) {
$css_list->remove( $item );
return array();
}
$this->processed_imported_stylesheet_urls[ $import_stylesheet_url ] = true;
// Prevent importing font stylesheets from allowed font CDNs. These will get added to the document as links instead.
$https_import_stylesheet_url = preg_replace( '#^(http:)?(?=//)#', 'https:', $import_stylesheet_url );
if ( $this->allowed_font_src_regex && preg_match( $this->allowed_font_src_regex, $https_import_stylesheet_url ) ) {
$this->imported_font_urls[] = $https_import_stylesheet_url;
$css_list->remove( $item );
_doing_it_wrong(
'wp_enqueue_style',
esc_html( sprintf(
/* translators: %s is URL to font CDN */
__( 'It is not a best practice to use @import to load font CDN stylesheets. Please use wp_enqueue_style() to enqueue %s as its own separate script.', 'amp' ),
$import_stylesheet_url
) ),
'1.0'
);
return array();
}
$css_file_path = $this->get_validated_url_file_path( $import_stylesheet_url, array( 'css', 'less', 'scss', 'sass' ) );
if ( is_wp_error( $css_file_path ) && ( 'disallowed_file_extension' === $css_file_path->get_error_code() || 'external_file_url' === $css_file_path->get_error_code() ) ) {
$contents = $this->fetch_external_stylesheet( $import_stylesheet_url );
if ( is_wp_error( $contents ) ) {
$error = array(
'code' => $contents->get_error_code(),
'message' => $contents->get_error_message(),
'type' => AMP_Validation_Error_Taxonomy::CSS_ERROR_TYPE,
);
$sanitized = $this->should_sanitize_validation_error( $error );
if ( $sanitized ) {
$css_list->remove( $item );
}
$results[] = compact( 'error', 'sanitized' );
return $results;
} else {
$stylesheet = $contents;
}
} elseif ( is_wp_error( $css_file_path ) ) {
$error = array(
'code' => $css_file_path->get_error_code(),
'message' => $css_file_path->get_error_message(),
'type' => AMP_Validation_Error_Taxonomy::CSS_ERROR_TYPE,
);
$sanitized = $this->should_sanitize_validation_error( $error );
if ( $sanitized ) {
$css_list->remove( $item );
}
$results[] = compact( 'error', 'sanitized' );
return $results;
} else {
$stylesheet = file_get_contents( $css_file_path ); // phpcs:ignore -- It's a local filesystem path not a remote request.
}
if ( $media_query ) {
$stylesheet = sprintf( '@media %s { %s }', $media_query, $stylesheet );
}
$options['stylesheet_url'] = $import_stylesheet_url;
$parsed_stylesheet = $this->parse_stylesheet( $stylesheet, $options );
$results = array_merge(
$results,
$parsed_stylesheet['validation_results']
);
/**
* CSS Doc.
*
* @var Document $css_document
*/
$css_document = $parsed_stylesheet['css_document'];
if ( ! empty( $parsed_stylesheet['css_document'] ) ) {
$css_list->replace( $item, $css_document->getContents() );
} else {
$css_list->remove( $item );
}
return $results;
}
/**
* 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 Document $css_document CSS Document.
* @type array $validation_results Validation results, array containing arrays with error and sanitized keys.
* }
*/
private function parse_stylesheet( $stylesheet_string, $options ) {
$validation_results = array();
$css_document = null;
$this->imported_font_urls = array();
try {
// Remove spaces from data URLs, which cause errors and PHP-CSS-Parser can't handle them.
$stylesheet_string = $this->remove_spaces_from_data_urls( $stylesheet_string );
$parser_settings = Sabberworm\CSS\Settings::create();
$css_parser = new Sabberworm\CSS\Parser( $stylesheet_string, $parser_settings );
$css_document = $css_parser->parse(); // @todo If 'utf-8' is not $css_parser->getCharset() then issue warning?
if ( ! empty( $options['stylesheet_url'] ) ) {
$this->real_path_urls(
array_filter(
$css_document->getAllValues(),
function ( $value ) {
return $value instanceof URL;
}
),
$options['stylesheet_url']
);
}
$validation_results = array_merge(
$validation_results,
$this->process_css_list( $css_document, $options )
);
} catch ( Exception $exception ) {
$error = array(
'code' => 'css_parse_error',
'message' => $exception->getMessage(),
'type' => AMP_Validation_Error_Taxonomy::CSS_ERROR_TYPE,
);
/*
* This is not a recoverable error, so sanitized here is just used to give user control