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class-amp-tag-and-attribute-sanitizer.php
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<?php
/**
* Class AMP_Tag_And_Attribute_Sanitizer
*
* @package AMP
*/
use Amp\AmpWP\Dom\Document;
/**
* Strips the tags and attributes from the content that are not allowed by the AMP spec.
*
* Allowed tags array is generated from this protocol buffer:
*
* https://github.com/ampproject/amphtml/blob/master/validator/validator-main.protoascii
* by the python script in amp-wp/bin/amp_wp_build.py. See the comment at the top
* of that file for instructions to generate class-amp-allowed-tags-generated.php.
*
* @todo Need to check the following items that are not yet checked by this sanitizer:
*
* - `also_requires_attr` - if one attribute is present, this requires another.
* - `ChildTagSpec` - Places restrictions on the number and type of child tags.
* - `if_value_regex` - if one attribute value matches, this places a restriction
* on another attribute/value.
*/
class AMP_Tag_And_Attribute_Sanitizer extends AMP_Base_Sanitizer {
const DISALLOWED_TAG = 'DISALLOWED_TAG';
const DISALLOWED_TAG_MULTIPLE_CHOICES = 'DISALLOWED_TAG_MULTIPLE_CHOICES';
const DISALLOWED_CHILD_TAG = 'DISALLOWED_CHILD_TAG';
const DISALLOWED_FIRST_CHILD_TAG = 'DISALLOWED_FIRST_CHILD_TAG';
const INCORRECT_NUM_CHILD_TAGS = 'INCORRECT_NUM_CHILD_TAGS';
const INCORRECT_MIN_NUM_CHILD_TAGS = 'INCORRECT_MIN_NUM_CHILD_TAGS';
const WRONG_PARENT_TAG = 'WRONG_PARENT_TAG';
const DISALLOWED_TAG_ANCESTOR = 'DISALLOWED_TAG_ANCESTOR';
const MANDATORY_TAG_ANCESTOR = 'MANDATORY_TAG_ANCESTOR';
const DISALLOWED_DESCENDANT_TAG = 'DISALLOWED_DESCENDANT_TAG';
const DISALLOWED_ATTR = 'DISALLOWED_ATTR';
const DISALLOWED_PROCESSING_INSTRUCTION = 'DISALLOWED_PROCESSING_INSTRUCTION';
const CDATA_VIOLATES_BLACKLIST = 'CDATA_VIOLATES_BLACKLIST';
const DUPLICATE_UNIQUE_TAG = 'DUPLICATE_UNIQUE_TAG';
const MANDATORY_CDATA_MISSING_OR_INCORRECT = 'MANDATORY_CDATA_MISSING_OR_INCORRECT';
const CDATA_TOO_LONG = 'CDATA_TOO_LONG';
const INVALID_CDATA_CSS_IMPORTANT = 'INVALID_CDATA_CSS_IMPORTANT';
const INVALID_CDATA_CONTENTS = 'INVALID_CDATA_CONTENTS';
const INVALID_CDATA_HTML_COMMENTS = 'INVALID_CDATA_HTML_COMMENTS';
const INVALID_ATTR_VALUE = 'INVALID_ATTR_VALUE';
const INVALID_ATTR_VALUE_CASEI = 'INVALID_ATTR_VALUE_CASEI';
const INVALID_ATTR_VALUE_REGEX = 'INVALID_ATTR_VALUE_REGEX';
const INVALID_ATTR_VALUE_REGEX_CASEI = 'INVALID_ATTR_VALUE_REGEX_CASEI';
const INVALID_URL_PROTOCOL = 'INVALID_URL_PROTOCOL';
const INVALID_URL = 'INVALID_URL';
const DISALLOWED_RELATIVE_URL = 'DISALLOWED_RELATIVE_URL';
const DISALLOWED_EMPTY_URL = 'DISALLOWED_EMPTY_URL';
const INVALID_BLACKLISTED_VALUE_REGEX = 'INVALID_BLACKLISTED_VALUE_REGEX';
const DISALLOWED_PROPERTY_IN_ATTR_VALUE = 'DISALLOWED_PROPERTY_IN_ATTR_VALUE';
const MISSING_MANDATORY_PROPERTY = 'MISSING_MANDATORY_PROPERTY';
const MISSING_REQUIRED_PROPERTY_VALUE = 'MISSING_REQUIRED_PROPERTY_VALUE';
const ATTR_REQUIRED_BUT_MISSING = 'ATTR_REQUIRED_BUT_MISSING';
const MANDATORY_ANYOF_ATTR_MISSING = 'MANDATORY_ANYOF_ATTR_MISSING';
const MANDATORY_ONEOF_ATTR_MISSING = 'MANDATORY_ONEOF_ATTR_MISSING';
const DUPLICATE_ONEOF_ATTRS = 'DUPLICATE_ONEOF_ATTRS';
const INVALID_LAYOUT_WIDTH = 'INVALID_LAYOUT_WIDTH';
const INVALID_LAYOUT_HEIGHT = 'INVALID_LAYOUT_HEIGHT';
const INVALID_LAYOUT_AUTO_HEIGHT = 'INVALID_LAYOUT_AUTO_HEIGHT';
const INVALID_LAYOUT_NO_HEIGHT = 'INVALID_LAYOUT_NO_HEIGHT';
const INVALID_LAYOUT_FIXED_HEIGHT = 'INVALID_LAYOUT_FIXED_HEIGHT';
const INVALID_LAYOUT_AUTO_WIDTH = 'INVALID_LAYOUT_AUTO_WIDTH';
const INVALID_LAYOUT_UNIT_DIMENSIONS = 'INVALID_LAYOUT_UNIT_DIMENSIONS';
const INVALID_LAYOUT_HEIGHTS = 'INVALID_LAYOUT_HEIGHTS';
/**
* Allowed tags.
*
* @since 0.5
*
* @var string[]
*/
protected $allowed_tags;
/**
* Globally-allowed attributes.
*
* @since 0.5
*
* @var array[][]
*/
protected $globally_allowed_attributes;
/**
* Layout-allowed attributes.
*
* @since 0.5
*
* @var string[]
*/
protected $layout_allowed_attributes;
/**
* Mapping of alternative names back to their primary names.
*
* @since 0.7
* @var array
*/
protected $rev_alternate_attr_name_lookup = [];
/**
* Mapping of JSON-serialized tag spec to the number of instances encountered in the document.
*
* @var array
*/
protected $visited_unique_tag_specs = [];
/**
* Default args.
*
* @since 0.5
*
* @var array
*/
protected $DEFAULT_ARGS = [];
/**
* AMP script components that are discovered being required through sanitization.
*
* @var string[]
*/
protected $script_components = [];
/**
* Keep track of nodes that should not be replaced to prevent duplicated validation errors since sanitization is rejected.
*
* @var array
*/
protected $should_not_replace_nodes = [];
/**
* Keep track of the elements that are currently open.
*
* This is used to determine whether a node exists inside of a given element tree, speeding up has_ancestor checks
* as well as disabling attribute validation inside of templates.
*
* @see \AMP_Tag_And_Attribute_Sanitizer::has_ancestor()
* @since 1.3
* @var array
*/
protected $open_elements = [];
/**
* AMP_Tag_And_Attribute_Sanitizer constructor.
*
* @since 0.5
*
* @param Document $dom DOM.
* @param array $args Args.
*/
public function __construct( $dom, $args = [] ) {
// @todo It is pointless to have this DEFAULT_ARGS copying the array values. We should only get the data from AMP_Allowed_Tags_Generated.
$this->DEFAULT_ARGS = [
'amp_allowed_tags' => AMP_Allowed_Tags_Generated::get_allowed_tags(),
'amp_globally_allowed_attributes' => AMP_Allowed_Tags_Generated::get_allowed_attributes(),
'amp_layout_allowed_attributes' => AMP_Allowed_Tags_Generated::get_layout_attributes(),
];
parent::__construct( $dom, $args );
// @todo AMP dev mode should eventually be used instead of allow_dirty_styles.
if ( ! empty( $this->args['allow_dirty_styles'] ) ) {
// Allow style attribute on all elements.
$this->args['amp_globally_allowed_attributes']['style'] = [];
// Remove restrictions on use of !important.
foreach ( $this->args['amp_allowed_tags']['style'] as &$style ) {
$style['cdata'] = [];
}
// Allow style elements.
$this->args['amp_allowed_tags']['style'][] = [
'attr_spec_list' => [
'type' => [
'value_casei' => 'text/css',
],
],
'cdata' => [],
'tag_spec' => [
'spec_name' => 'style for Customizer preview',
],
];
// Allow stylesheet links.
$this->args['amp_allowed_tags']['link'][] = [
'attr_spec_list' => [
'async' => [],
'crossorigin' => [],
'href' => [
'mandatory' => true,
],
'integrity' => [],
'media' => [],
'rel' => [
'dispatch_key' => 2,
'mandatory' => true,
'value_casei' => 'stylesheet',
],
'type' => [
'value_casei' => 'text/css',
],
],
'tag_spec' => [
'spec_name' => 'link rel=stylesheet for Customizer preview', // phpcs:ignore WordPress.WP.EnqueuedResources.NonEnqueuedStylesheet
],
];
}
// @todo AMP dev mode should eventually be used instead of allow_dirty_scripts.
// Allow scripts if requested.
if ( ! empty( $this->args['allow_dirty_scripts'] ) ) {
$this->args['amp_allowed_tags']['script'][] = [
'attr_spec_list' => [
'type' => [],
'src' => [],
'async' => [],
'defer' => [],
],
'cdata' => [],
'tag_spec' => [
'spec_name' => 'scripts for Customizer preview',
],
];
}
// Prepare whitelists.
$this->allowed_tags = $this->args['amp_allowed_tags'];
foreach ( AMP_Rule_Spec::$additional_allowed_tags as $tag_name => $tag_rule_spec ) {
$this->allowed_tags[ $tag_name ][] = $tag_rule_spec;
}
// @todo Do the same for body when !use_document_element?
if ( ! empty( $this->args['use_document_element'] ) ) {
foreach ( $this->allowed_tags['html'] as &$rule_spec ) {
unset( $rule_spec[ AMP_Rule_Spec::TAG_SPEC ][ AMP_Rule_Spec::MANDATORY_PARENT ] );
}
unset( $rule_spec );
}
foreach ( $this->allowed_tags as &$tag_specs ) {
foreach ( $tag_specs as &$tag_spec ) {
if ( isset( $tag_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ] ) ) {
$tag_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ] = $this->process_alternate_names( $tag_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ] );
}
}
unset( $tag_spec );
}
unset( $tag_specs );
$this->globally_allowed_attributes = $this->process_alternate_names( $this->args['amp_globally_allowed_attributes'] );
$this->layout_allowed_attributes = $this->process_alternate_names( $this->args['amp_layout_allowed_attributes'] );
}
/**
* Return array of values that would be valid as an HTML `script` element.
*
* Array keys are AMP element names and array values are their respective
* Javascript URLs from https://cdn.ampproject.org
*
* @since 0.7
* @see amp_register_default_scripts()
*
* @return array() Returns component name as array key and true as value (or JavaScript URL string),
* respectively. When true then the default component script URL will be used.
* Will return an empty array if sanitization has yet to be run
* or if it did not find any HTML elements to convert to AMP equivalents.
*/
public function get_scripts() {
return array_fill_keys( array_unique( $this->script_components ), true );
}
/**
* Process alternative names in attribute spec list.
*
* @since 0.7
*
* @param array $attr_spec_list Attribute spec list.
* @return array Modified attribute spec list.
*/
private function process_alternate_names( $attr_spec_list ) {
foreach ( $attr_spec_list as $attr_name => &$attr_spec ) {
// Save all alternative names in lookup to improve performance.
if ( isset( $attr_spec[ AMP_Rule_Spec::ALTERNATIVE_NAMES ] ) ) {
foreach ( $attr_spec[ AMP_Rule_Spec::ALTERNATIVE_NAMES ] as $alternative_name ) {
$this->rev_alternate_attr_name_lookup[ $alternative_name ] = $attr_name;
}
}
}
return $attr_spec_list;
}
/**
* Sanitize the elements from the HTML contained in this instance's Dom\Document.
*
* @since 0.5
*/
public function sanitize() {
$result = $this->sanitize_element( $this->root_element );
if ( is_array( $result ) ) {
$this->script_components = $result;
}
}
/**
* Sanitize element.
*
* Walk the DOM tree with depth first search (DFS) with post order traversal (LRN).
*
* @param DOMElement $element Element.
* @return string[]|null Required component scripts from sanitizing an element tree, or null if the element was removed.
*/
private function sanitize_element( DOMElement $element ) {
if ( ! isset( $this->open_elements[ $element->nodeName ] ) ) {
$this->open_elements[ $element->nodeName ] = 0;
}
$this->open_elements[ $element->nodeName ]++;
$script_components = [];
// First recurse into children to sanitize descendants.
// The check for $element->parentNode at each iteration is to make sure an invalid child didn't bubble up removed
// ancestor nodes in AMP_Tag_And_Attribute_Sanitizer::remove_node().
$this_child = $element->firstChild;
while ( $this_child && $element->parentNode ) {
$next_child = $this_child->nextSibling;
if ( $this_child instanceof DOMElement ) {
$result = $this->sanitize_element( $this_child );
if ( is_array( $result ) ) {
$script_components = array_merge(
$script_components,
$result
);
}
} elseif ( $this_child instanceof DOMProcessingInstruction ) {
$this->remove_invalid_child( $this_child, [ 'code' => self::DISALLOWED_PROCESSING_INSTRUCTION ] );
}
$this_child = $next_child;
}
// If the element is still in the tree, process it.
// The element can currently be removed from the tree when processing children via AMP_Tag_And_Attribute_Sanitizer::remove_node().
$was_removed = false;
if ( $element->parentNode ) {
$result = $this->process_node( $element );
if ( is_array( $result ) ) {
$script_components = array_merge( $script_components, $result );
} else {
$was_removed = true;
}
}
$this->open_elements[ $element->nodeName ]--;
if ( $was_removed ) {
return null;
}
return $script_components;
}
/**
* Augment rule spec for validation.
*
* @since 1.0
*
* @param DOMElement $node Node.
* @param array $rule_spec Rule spec.
* @return array Augmented rule spec.
*/
private function get_rule_spec_list_to_validate( DOMElement $node, $rule_spec ) {
// Expand extension_spec into a set of attr_spec_list.
if ( isset( $rule_spec[ AMP_Rule_Spec::TAG_SPEC ]['extension_spec'] ) ) {
$extension_spec = $rule_spec[ AMP_Rule_Spec::TAG_SPEC ]['extension_spec'];
// This could also be derived from the extension_type in the extension_spec.
$custom_attr = 'amp-mustache' === $extension_spec['name'] ? 'custom-template' : 'custom-element';
$rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ][ $custom_attr ] = [
AMP_Rule_Spec::VALUE => $extension_spec['name'],
AMP_Rule_Spec::MANDATORY => true,
];
$rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ]['src'] = [
AMP_Rule_Spec::VALUE_REGEX => implode(
'',
[
'^',
preg_quote( 'https://cdn.ampproject.org/v0/' . $extension_spec['name'] . '-' ), // phpcs:ignore WordPress.PHP.PregQuoteDelimiter.Missing
'(' . implode( '|', array_merge( $extension_spec['version'], [ 'latest' ] ) ) . ')',
'\.js$',
]
),
];
}
// Augment the attribute list according to the parent's reference points, if it has them.
if ( ! empty( $node->parentNode ) && isset( $this->allowed_tags[ $node->parentNode->nodeName ] ) ) {
foreach ( $this->allowed_tags[ $node->parentNode->nodeName ] as $parent_rule_spec ) {
if ( empty( $parent_rule_spec[ AMP_Rule_Spec::TAG_SPEC ]['reference_points'] ) ) {
continue;
}
foreach ( $parent_rule_spec[ AMP_Rule_Spec::TAG_SPEC ]['reference_points'] as $reference_point_spec_name => $reference_point_spec_instance_attrs ) {
$reference_point = AMP_Allowed_Tags_Generated::get_reference_point_spec( $reference_point_spec_name );
if ( empty( $reference_point[ AMP_Rule_Spec::ATTR_SPEC_LIST ] ) ) {
/*
* See special case for amp-selector in AMP_Tag_And_Attribute_Sanitizer::is_amp_allowed_attribute()
* where its reference point applies to any descendant elements, not just direct children.
*/
continue;
}
foreach ( $reference_point[ AMP_Rule_Spec::ATTR_SPEC_LIST ] as $attr_name => $reference_point_spec_attr ) {
$reference_point_spec_attr = array_merge(
$reference_point_spec_attr,
$reference_point_spec_instance_attrs
);
/*
* Ignore mandatory constraint for now since this would end up causing other sibling children
* getting removed due to missing a mandatory attribute. To sanitize this it would require
* higher-level processing to look at an element's surrounding context, similar to how the
* sanitizer does not yet handle the mandatory_oneof constraint.
*/
unset( $reference_point_spec_attr['mandatory'] );
$rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ][ $attr_name ] = $reference_point_spec_attr;
}
}
}
}
return $rule_spec;
}
/**
* Process a node by checking if an element and its attributes are valid, and removing them when invalid.
*
* Attributes which are not valid are removed. Elements which are not allowed are also removed,
* including elements which miss mandatory attributes.
*
* @param DOMElement $node Node.
* @return string[]|null Required scripts, or null if the element was removed.
*/
private function process_node( DOMElement $node ) {
// Remove nodes with tags that have not been whitelisted.
if ( ! $this->is_amp_allowed_tag( $node ) ) {
// If it's not an allowed tag, replace the node with it's children.
$this->replace_node_with_children( $node );
// Return early since this node no longer exists.
return null;
}
/*
* Compile a list of rule_specs to validate for this node
* based on tag name of the node.
*/
$rule_spec_list_to_validate = [];
$validation_errors = [];
$rule_spec_list = $this->allowed_tags[ $node->nodeName ];
foreach ( $rule_spec_list as $id => $rule_spec ) {
$validity = $this->validate_tag_spec_for_node( $node, $rule_spec[ AMP_Rule_Spec::TAG_SPEC ] );
if ( true === $validity ) {
$rule_spec_list_to_validate[ $id ] = $this->get_rule_spec_list_to_validate( $node, $rule_spec );
} else {
$validation_errors[] = array_merge(
$validity,
[ 'spec_name' => $this->get_spec_name( $node, $rule_spec[ AMP_Rule_Spec::TAG_SPEC ] ) ]
);
}
}
// If no valid rule_specs exist, then remove this node and return.
if ( empty( $rule_spec_list_to_validate ) ) {
if ( 1 === count( $validation_errors ) ) {
// If there was only one tag spec candidate that failed, use its error code for removing the node,
// since we know it is the specific reason for why the node had to be removed.
// This is the normal case.
$this->remove_invalid_child(
$node,
$validation_errors[0]
);
} else {
$spec_names = wp_list_pluck( $validation_errors, 'spec_name' );
$unique_validation_error_count = count(
array_unique(
array_map(
static function ( $validation_error ) {
unset( $validation_error['spec_name'] );
return $validation_error;
},
$validation_errors
),
SORT_REGULAR
)
);
if ( 1 === $unique_validation_error_count ) {
// If all of the validation errors are the same except for the spec_name, use the common error code.
$validation_error = $validation_errors[0];
unset( $validation_error['spec_name'] );
$this->remove_invalid_child(
$node,
array_merge(
$validation_error,
compact( 'spec_names' )
)
);
} else {
// Otherwise, we have a rare condition where multiple tag specs fail for different reasons.
$this->remove_invalid_child(
$node,
[
'code' => self::DISALLOWED_TAG_MULTIPLE_CHOICES,
'errors' => $validation_errors,
]
);
}
}
return null;
}
// The remaining validations all have to do with attributes.
$attr_spec_list = [];
$tag_spec = [];
$cdata = [];
/*
* If we have exactly one rule_spec, use it's attr_spec_list
* to validate the node's attributes.
*/
if ( 1 === count( $rule_spec_list_to_validate ) ) {
$rule_spec = array_pop( $rule_spec_list_to_validate );
$attr_spec_list = $rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ];
$tag_spec = $rule_spec[ AMP_Rule_Spec::TAG_SPEC ];
if ( isset( $rule_spec[ AMP_Rule_Spec::CDATA ] ) ) {
$cdata = $rule_spec[ AMP_Rule_Spec::CDATA ];
}
} else {
/*
* If there is more than one valid rule_spec for this node,
* then try to deduce which one is intended by inspecting
* the node's attributes.
*/
/*
* Get a score from each attr_spec_list by seeing how many
* attributes and values match the node.
*/
$attr_spec_scores = [];
foreach ( $rule_spec_list_to_validate as $spec_id => $rule_spec ) {
$attr_spec_scores[ $spec_id ] = $this->validate_attr_spec_list_for_node( $node, $rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ] );
}
// Remove all spec lists that didn't match.
$attr_spec_scores = array_filter( $attr_spec_scores );
// If no attribute spec lists match, then the element must be removed.
if ( empty( $attr_spec_scores ) ) {
$this->remove_node( $node );
return null;
}
// Get the key(s) to the highest score(s).
$spec_ids_sorted = array_keys( $attr_spec_scores, max( $attr_spec_scores ), true );
// If there is exactly one attr_spec with a max score, use that one.
if ( 1 === count( $spec_ids_sorted ) ) {
$attr_spec_list = $rule_spec_list_to_validate[ $spec_ids_sorted[0] ][ AMP_Rule_Spec::ATTR_SPEC_LIST ];
$tag_spec = $rule_spec_list_to_validate[ $spec_ids_sorted[0] ][ AMP_Rule_Spec::TAG_SPEC ];
if ( isset( $rule_spec_list_to_validate[ $spec_ids_sorted[0] ][ AMP_Rule_Spec::CDATA ] ) ) {
$cdata = $rule_spec_list_to_validate[ $spec_ids_sorted[0] ][ AMP_Rule_Spec::CDATA ];
}
} else {
// This should not happen very often, but...
// If we're here, then we're not sure which spec should
// be used. Let's use the top scoring ones.
foreach ( $spec_ids_sorted as $id ) {
$attr_spec_list = array_merge(
$attr_spec_list,
$rule_spec_list_to_validate[ $id ][ AMP_Rule_Spec::ATTR_SPEC_LIST ]
);
$tag_spec = array_merge(
$tag_spec,
$rule_spec_list_to_validate[ $id ][ AMP_Rule_Spec::TAG_SPEC ]
);
if ( isset( $rule_spec_list_to_validate[ $id ][ AMP_Rule_Spec::CDATA ] ) ) {
$cdata = array_merge( $cdata, $rule_spec_list_to_validate[ $id ][ AMP_Rule_Spec::CDATA ] );
}
}
$first_spec = reset( $rule_spec_list_to_validate );
if ( empty( $attr_spec_list ) && isset( $first_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ] ) ) {
$attr_spec_list = $first_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ];
}
}
}
// Remove element if it has illegal CDATA.
if ( ! empty( $cdata ) && $node instanceof DOMElement ) {
$validity = $this->validate_cdata_for_node( $node, $cdata );
if ( true !== $validity ) {
$this->remove_invalid_child(
$node,
array_merge(
$validity,
[ 'spec_name' => $this->get_spec_name( $node, $tag_spec ) ]
)
);
return null;
}
}
$merged_attr_spec_list = array_merge(
$this->globally_allowed_attributes,
$attr_spec_list
);
// Amend spec list with layout.
if ( isset( $tag_spec['amp_layout'] ) ) {
$merged_attr_spec_list = array_merge( $merged_attr_spec_list, $this->layout_allowed_attributes );
if ( isset( $tag_spec['amp_layout']['supported_layouts'] ) ) {
$layouts = wp_array_slice_assoc( AMP_Rule_Spec::$layout_enum, $tag_spec['amp_layout']['supported_layouts'] );
$merged_attr_spec_list['layout'][ AMP_Rule_Spec::VALUE_REGEX_CASEI ] = '(' . implode( '|', $layouts ) . ')';
}
}
// Enforce unique constraint.
if ( ! empty( $tag_spec['unique'] ) ) {
$removed = false;
$tag_spec_key = wp_json_encode( $tag_spec );
if ( ! empty( $this->visited_unique_tag_specs[ $node->nodeName ][ $tag_spec_key ] ) ) {
$removed = $this->remove_invalid_child(
$node,
[
'code' => self::DUPLICATE_UNIQUE_TAG,
'spec_name' => $this->get_spec_name( $node, $tag_spec ),
]
);
}
$this->visited_unique_tag_specs[ $node->nodeName ][ $tag_spec_key ] = true;
if ( $removed ) {
return null;
}
}
// Remove the element if it is has an invalid layout.
$layout_validity = $this->is_valid_layout( $tag_spec, $node );
if ( true !== $layout_validity ) {
$this->remove_invalid_child( $node, $layout_validity );
return null;
}
// Identify attribute values that don't conform to the attr_spec.
$disallowed_attributes = $this->sanitize_disallowed_attribute_values_in_node( $node, $merged_attr_spec_list );
// Remove all invalid attributes.
if ( ! empty( $disallowed_attributes ) ) {
/*
* Capture all element attributes up front so that differing validation errors result when
* one invalid attribute is accepted but the others are still rejected.
*/
$element_attributes = [];
foreach ( $node->attributes as $attribute ) {
$element_attributes[ $attribute->nodeName ] = $attribute->nodeValue;
}
$removed_attributes = [];
foreach ( $disallowed_attributes as $disallowed_attribute ) {
/**
* Returned vars.
*
* @var DOMAttr $attr_node
* @var string $error_code
* @var array $error_data
*/
list( $attr_node, $error_code, $error_data ) = $disallowed_attribute;
$validation_error = [
'code' => $error_code,
'element_attributes' => $element_attributes,
];
if ( self::DISALLOWED_PROPERTY_IN_ATTR_VALUE === $error_code ) {
$properties = $this->parse_properties_attribute( $attr_node->nodeValue );
$validation_error['meta_property_name'] = $error_data['name'];
if ( ! $this->is_empty_attribute_value( $properties[ $error_data['name'] ] ) ) {
$validation_error['meta_property_value'] = $properties[ $error_data['name'] ];
}
if ( $this->should_sanitize_validation_error( $validation_error, [ 'node' => $attr_node ] ) ) {
unset( $properties[ $error_data['name'] ] );
$node->setAttribute( $attr_node->nodeName, $this->serialize_properties_attribute( $properties ) );
}
} elseif ( self::MISSING_REQUIRED_PROPERTY_VALUE === $error_code ) {
$validation_error['meta_property_name'] = $error_data['name'];
$validation_error['meta_property_value'] = $error_data['value'];
$validation_error['meta_property_required_value'] = $error_data['required_value'];
if ( $this->should_sanitize_validation_error( $validation_error, [ 'node' => $attr_node ] ) ) {
$properties = $this->parse_properties_attribute( $attr_node->nodeValue );
if ( ! empty( $merged_attr_spec_list[ $attr_node->nodeName ]['value_properties'][ $error_data['name'] ]['mandatory'] ) ) {
$properties[ $error_data['name'] ] = $error_data['required_value'];
} else {
unset( $properties[ $error_data['name'] ] );
}
$node->setAttribute( $attr_node->nodeName, $this->serialize_properties_attribute( $properties ) );
}
} elseif ( self::MISSING_MANDATORY_PROPERTY === $error_code ) {
$validation_error['meta_property_name'] = $error_data['name'];
$validation_error['meta_property_required_value'] = $error_data['required_value'];
if ( $this->should_sanitize_validation_error( $validation_error, [ 'node' => $attr_node ] ) ) {
$properties = array_merge(
$this->parse_properties_attribute( $attr_node->nodeValue ),
[ $error_data['name'] => $error_data['required_value'] ]
);
$node->setAttribute( $attr_node->nodeName, $this->serialize_properties_attribute( $properties ) );
}
} else {
$attr_spec = isset( $merged_attr_spec_list[ $attr_node->nodeName ] ) ? $merged_attr_spec_list[ $attr_node->nodeName ] : [];
if ( $this->remove_invalid_attribute( $node, $attr_node, $validation_error, $attr_spec ) ) {
$removed_attributes[] = $attr_node;
}
}
}
/*
* Only run cleanup after the fact to prevent a scenario where invalid markup is kept and so the attribute
* is actually not removed. This prevents a "DOMException: Not Found Error" from happening when calling
* remove_invalid_attribute() since clean_up_after_attribute_removal() can end up removing invalid link
* attributes (like 'target') when there is an invalid 'href' attribute, but if the 'target' attribute is
* itself invalid, then if clean_up_after_attribute_removal() is called inside of remove_invalid_attribute()
* it can cause a subsequent invocation of remove_invalid_attribute() to try to remove an invalid
* attribute that has already been removed from the DOM.
*/
foreach ( $removed_attributes as $removed_attribute ) {
$this->clean_up_after_attribute_removal( $node, $removed_attribute );
}
}
if ( ! empty( $tag_spec[ AMP_Rule_Spec::DESCENDANT_TAG_LIST ] ) ) {
$allowed_tags = AMP_Allowed_Tags_Generated::get_descendant_tag_list( $tag_spec[ AMP_Rule_Spec::DESCENDANT_TAG_LIST ] );
if ( ! empty( $allowed_tags ) ) {
$this->remove_disallowed_descendants( $node, $allowed_tags, $this->get_spec_name( $node, $tag_spec ) );
}
}
// After attributes have been sanitized (and potentially removed), if mandatory attribute(s) are missing, remove the element.
$missing_mandatory_attributes = $this->get_missing_mandatory_attributes( $merged_attr_spec_list, $node );
if ( ! empty( $missing_mandatory_attributes ) ) {
$this->remove_invalid_child(
$node,
[
'code' => self::ATTR_REQUIRED_BUT_MISSING,
'attributes' => $missing_mandatory_attributes,
'spec_name' => $this->get_spec_name( $node, $tag_spec ),
]
);
return null;
}
if ( ! empty( $tag_spec[ AMP_Rule_Spec::MANDATORY_ANYOF ] ) ) {
$anyof_attributes = $this->get_element_attribute_intersection( $node, $tag_spec[ AMP_Rule_Spec::MANDATORY_ANYOF ] );
if ( 0 === count( $anyof_attributes ) ) {
$this->remove_invalid_child(
$node,
[
'code' => self::MANDATORY_ANYOF_ATTR_MISSING,
'mandatory_anyof_attrs' => $tag_spec[ AMP_Rule_Spec::MANDATORY_ANYOF ], // @todo Temporary as value can be looked up via spec name. See https://github.com/ampproject/amp-wp/pull/3817.
'spec_name' => $this->get_spec_name( $node, $tag_spec ),
]
);
return null;
}
}
if ( ! empty( $tag_spec[ AMP_Rule_Spec::MANDATORY_ONEOF ] ) ) {
$oneof_attributes = $this->get_element_attribute_intersection( $node, $tag_spec[ AMP_Rule_Spec::MANDATORY_ONEOF ] );
if ( 0 === count( $oneof_attributes ) ) {
$this->remove_invalid_child(
$node,
[
'code' => self::MANDATORY_ONEOF_ATTR_MISSING,
'mandatory_oneof_attrs' => $tag_spec[ AMP_Rule_Spec::MANDATORY_ONEOF ], // @todo Temporary as value can be looked up via spec name. See https://github.com/ampproject/amp-wp/pull/3817.
'spec_name' => $this->get_spec_name( $node, $tag_spec ),
]
);
return null;
} elseif ( count( $oneof_attributes ) > 1 ) {
$this->remove_invalid_child(
$node,
[
'code' => self::DUPLICATE_ONEOF_ATTRS,
'duplicate_oneof_attrs' => $oneof_attributes,
'spec_name' => $this->get_spec_name( $node, $tag_spec ),
]
);
return null;
}
}
// Add required AMP component scripts.
$script_components = [];
if ( ! empty( $tag_spec['requires_extension'] ) ) {
$script_components = array_merge( $script_components, $tag_spec['requires_extension'] );
}
// Add required AMP components for attributes.
foreach ( $node->attributes as $attribute ) {
if ( isset( $merged_attr_spec_list[ $attribute->nodeName ]['requires_extension'] ) ) {
$script_components = array_merge(
$script_components,
$merged_attr_spec_list[ $attribute->nodeName ]['requires_extension']
);
}
}
// Manually add components for attributes; this is hard-coded because attributes do not have requires_extension like tags do. See <https://github.com/ampproject/amp-wp/issues/1808>.
if ( $node->hasAttribute( 'lightbox' ) ) {
$script_components[] = 'amp-lightbox-gallery';
}
// Check if element needs amp-bind component.
if ( $node instanceof DOMElement && ! in_array( 'amp-bind', $this->script_components, true ) ) {
foreach ( $node->attributes as $name => $value ) {
if ( Document::AMP_BIND_DATA_ATTR_PREFIX === substr( $name, 0, 14 ) ) {
$script_components[] = 'amp-bind';
break;
}
}
}
return $script_components;
}
/**
* Whether a node is missing a mandatory attribute.
*
* @param array $attr_spec The attribute specification.
* @param DOMElement $node The DOMElement of the node to check.
* @return bool $is_missing boolean Whether a required attribute is missing.
*/
public function is_missing_mandatory_attribute( $attr_spec, DOMElement $node ) {
return 0 !== count( $this->get_missing_mandatory_attributes( $attr_spec, $node ) );
}
/**
* Get list of mandatory missing mandatory attributes.
*
* @param array $attr_spec The attribute specification.
* @param DOMElement $node The DOMElement of the node to check.
* @return string[] Names of missing attributes.
*/
private function get_missing_mandatory_attributes( $attr_spec, DOMElement $node ) {
$missing_attributes = [];
foreach ( $attr_spec as $attr_name => $attr_spec_rule_value ) {
if ( '\u' === substr( $attr_name, 0, 2 ) ) {
$attr_name = html_entity_decode( '&#x' . substr( $attr_name, 2 ) . ';' ); // Probably ⚡.
}
if ( ! $node->hasAttribute( $attr_name ) && AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_mandatory( $node, $attr_name, $attr_spec_rule_value ) ) {
$missing_attributes[] = $attr_name;
}
}
return $missing_attributes;
}
/**
* Validate element for its CDATA.
*
* @since 0.7
*
* @param DOMElement $element Element.
* @param array $cdata_spec CDATA.
* @return true|array True when valid or error data when invalid.
*/
private function validate_cdata_for_node( DOMElement $element, $cdata_spec ) {
if (
isset( $cdata_spec['max_bytes'] ) && strlen( $element->textContent ) > $cdata_spec['max_bytes']
&&
// Skip the <style amp-custom> tag, as we want to display it even with an excessive size if it passed the style sanitizer.
// This would mean that AMP was disabled to not break the styling.
! ( 'style' === $element->nodeName && $element->hasAttribute( 'amp-custom' ) )
) {
return [
'code' => self::CDATA_TOO_LONG,
];
}
if ( isset( $cdata_spec['blacklisted_cdata_regex'] ) ) {
if ( preg_match( '@' . $cdata_spec['blacklisted_cdata_regex']['regex'] . '@u', $element->textContent ) ) {
if ( isset( $cdata_spec['blacklisted_cdata_regex']['error_message'] ) ) {
// There are only a few error messages, so map them to error codes.
switch ( $cdata_spec['blacklisted_cdata_regex']['error_message'] ) {
case 'CSS !important':
return [ 'code' => self::INVALID_CDATA_CSS_IMPORTANT ];
case 'contents':
return [ 'code' => self::INVALID_CDATA_CONTENTS ];
case 'html comments':
return [ 'code' => self::INVALID_CDATA_HTML_COMMENTS ];
}
}
// Note: This fallback case is not currently reachable because all error messages are accounted for in the switch statement.
return [ 'code' => self::CDATA_VIOLATES_BLACKLIST ];
}
} elseif ( isset( $cdata_spec['cdata_regex'] ) ) {
$delimiter = false === strpos( $cdata_spec['cdata_regex'], '@' ) ? '@' : '#';
if ( ! preg_match( $delimiter . $cdata_spec['cdata_regex'] . $delimiter . 'u', $element->textContent ) ) {
return [ 'code' => self::MANDATORY_CDATA_MISSING_OR_INCORRECT ];
}
}
return true;
}
/**
* Determines is a node is currently valid per its tag specification.
*
* Checks to see if a node's placement with the DOM is be valid for the
* given tag_spec. If there are restrictions placed on the type of node
* that can be an immediate parent or an ancestor of this node, then make
* sure those restrictions are met.
*
* This method has no side effects. It should not sanitize the DOM. It is purely to see if the spec matches.
*
* @since 0.5
*
* @param DOMElement $node The node to validate.
* @param array $tag_spec The specification.
* @return true|array True if node is valid for spec, or error data array if otherwise.
*/
private function validate_tag_spec_for_node( DOMElement $node, $tag_spec ) {
if ( ! empty( $tag_spec[ AMP_Rule_Spec::MANDATORY_PARENT ] ) && ! $this->has_parent( $node, $tag_spec[ AMP_Rule_Spec::MANDATORY_PARENT ] ) ) {
return [
'code' => self::WRONG_PARENT_TAG,
];
}
// Extension scripts must be in the head. Note this currently never fails because all AMP scripts are moved to the head before sanitization.
if ( isset( $tag_spec['extension_spec'] ) && ! $this->has_parent( $node, 'head' ) ) {
return [
'code' => self::WRONG_PARENT_TAG,
];
}
if ( ! empty( $tag_spec[ AMP_Rule_Spec::DISALLOWED_ANCESTOR ] ) ) {
foreach ( $tag_spec[ AMP_Rule_Spec::DISALLOWED_ANCESTOR ] as $disallowed_ancestor_node_name ) {
if ( $this->has_ancestor( $node, $disallowed_ancestor_node_name ) ) {
return [
'code' => self::DISALLOWED_TAG_ANCESTOR,
'disallowed_ancestor' => $disallowed_ancestor_node_name,
];
}
}
}
if ( ! empty( $tag_spec[ AMP_Rule_Spec::MANDATORY_ANCESTOR ] ) && ! $this->has_ancestor( $node, $tag_spec[ AMP_Rule_Spec::MANDATORY_ANCESTOR ] ) ) {
return [
'code' => self::MANDATORY_TAG_ANCESTOR,
];
}
if ( empty( $tag_spec[ AMP_Rule_Spec::CHILD_TAGS ] ) ) {
return true;
}
$validity = $this->check_valid_children( $node, $tag_spec[ AMP_Rule_Spec::CHILD_TAGS ] );
if ( true !== $validity ) {
$validity['tag_spec'] = $this->get_spec_name( $node, $tag_spec );
return $validity;
}
return true;
}
/**
* Checks to see if a spec is potentially valid.
*
* Checks the given node based on the attributes present in the node. This does not check every possible constraint
* imposed by the validator spec. It only performs the checks that are used to narrow down which set of attribute
* specs is most aligned with the given node. As of AMPHTML v1910161528000, the frequency of attribute spec
* constraints looks as follows:
*
* 433: value
* 400: mandatory
* 222: value_casei
* 147: blacklisted_value_regex
* 115: value_regex