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class-amp-tag-and-attribute-sanitizer.php
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<?php
/**
* Class AMP_Tag_And_Attribute_Sanitizer
*
* @package AMP
*/
/**
* 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.
* - `mandatory_oneof` - Within the context of the tag, exactly one of the attributes
* must be present.
*/
class AMP_Tag_And_Attribute_Sanitizer extends AMP_Base_Sanitizer {
/**
* 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 = array();
/**
* Stack.
*
* @since 0.5
*
* @var DOMElement[]
*/
private $stack = array();
/**
* Default args.
*
* @since 0.5
*
* @var array
*/
protected $DEFAULT_ARGS = array();
/**
* AMP script components that are discovered being required through sanitization.
*
* @var string[]
*/
protected $script_components = array();
/**
* 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 = array();
/**
* AMP_Tag_And_Attribute_Sanitizer constructor.
*
* @since 0.5
*
* @param DOMDocument $dom DOM.
* @param array $args Args.
*/
public function __construct( $dom, $args = array() ) {
$this->DEFAULT_ARGS = array(
'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(),
'amp_bind_placeholder_prefix' => AMP_DOM_Utils::get_amp_bind_placeholder_prefix(),
);
parent::__construct( $dom, $args );
if ( ! empty( $this->args['allow_dirty_styles'] ) ) {
// Allow style attribute on all elements.
$this->args['amp_globally_allowed_attributes']['style'] = array();
// Allow style elements.
$this->args['amp_allowed_tags']['style'][] = array(
'attr_spec_list' => array(
'type' => array(
'value_casei' => 'text/css',
),
),
'cdata' => array(),
'tag_spec' => array(
'spec_name' => 'style for Customizer preview',
),
);
// Allow stylesheet links.
$this->args['amp_allowed_tags']['link'][] = array(
'attr_spec_list' => array(
'async' => array(),
'crossorigin' => array(),
'href' => array(
'mandatory' => true,
),
'integrity' => array(),
'media' => array(),
'rel' => array(
'dispatch_key' => 2,
'mandatory' => true,
'value_casei' => 'stylesheet',
),
'type' => array(
'value_casei' => 'text/css',
),
),
'tag_spec' => array(
'spec_name' => 'link rel=stylesheet for Customizer preview', // phpcs:ignore WordPress.WP.EnqueuedResources.NonEnqueuedStylesheet
),
);
}
// Allow scripts if requested.
if ( ! empty( $this->args['allow_dirty_scripts'] ) ) {
$this->args['amp_allowed_tags']['script'][] = array(
'attr_spec_list' => array(
'type' => array(),
'src' => array(),
'async' => array(),
'defer' => array(),
),
'cdata' => array(),
'tag_spec' => array(
'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 ] );
}
}
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 ] );
}
}
}
$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 ) {
if ( '[' === $attr_name[0] ) {
$placeholder_attr_name = $this->args['amp_bind_placeholder_prefix'] . trim( $attr_name, '[]' );
if ( ! isset( $attr_spec[ AMP_Rule_Spec::ALTERNATIVE_NAMES ] ) ) {
$attr_spec[ AMP_Rule_Spec::ALTERNATIVE_NAMES ] = array();
}
$attr_spec[ AMP_Rule_Spec::ALTERNATIVE_NAMES ][] = $placeholder_attr_name;
}
// 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 DOMDocument.
*
* @since 0.5
*/
public function sanitize() {
// Add root of content to the stack.
$this->stack[] = $this->root_element;
/**
* This loop traverses through the DOM tree iteratively.
*/
while ( ! empty( $this->stack ) ) {
// Get the next node to process.
$node = array_shift( $this->stack );
/**
* Process this node.
*/
$this->process_node( $node );
/*
* Push child nodes onto the stack, if any exist.
* if node was removed, then it's parentNode value is null.
*/
if ( $node->parentNode ) {
$child = $node->firstChild;
while ( $child ) {
$this->stack[] = $child;
$child = $child->nextSibling;
}
}
}
}
/**
* 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( $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'];
$custom_attr = 'amp-mustache' === $extension_spec['name'] ? 'custom-template' : 'custom-element';
$rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ][ $custom_attr ] = array(
AMP_Rule_Spec::VALUE => $extension_spec['name'],
AMP_Rule_Spec::MANDATORY => true,
);
$versions = array_unique( array_merge(
isset( $extension_spec['allowed_versions'] ) ? $extension_spec['allowed_versions'] : array(),
isset( $extension_spec['version'] ) ? $extension_spec['version'] : array()
) );
$rule_spec[ AMP_Rule_Spec::ATTR_SPEC_LIST ]['src'] = array(
AMP_Rule_Spec::VALUE_REGEX => implode( '', array(
'^',
preg_quote( 'https://cdn.ampproject.org/v0/' . $extension_spec['name'] . '-' ),
'(' . implode( '|', $versions ) . ')',
'\.js$',
) ),
);
}
// 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 DOMNode $node Node.
*/
private function process_node( $node ) {
// Don't process text or comment nodes.
if ( XML_TEXT_NODE === $node->nodeType || XML_COMMENT_NODE === $node->nodeType || XML_CDATA_SECTION_NODE === $node->nodeType ) {
return;
}
// 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;
}
/**
* Node is now an element.
*
* @var DOMElement $node
*/
/*
* Compile a list of rule_specs to validate for this node
* based on tag name of the node.
*/
$rule_spec_list_to_validate = array();
$rule_spec_list = array();
if ( isset( $this->allowed_tags[ $node->nodeName ] ) ) {
$rule_spec_list = $this->allowed_tags[ $node->nodeName ];
}
foreach ( $rule_spec_list as $id => $rule_spec ) {
if ( $this->validate_tag_spec_for_node( $node, $rule_spec[ AMP_Rule_Spec::TAG_SPEC ] ) ) {
$rule_spec_list_to_validate[ $id ] = $this->get_rule_spec_list_to_validate( $node, $rule_spec );
}
}
// If no valid rule_specs exist, then remove this node and return.
if ( empty( $rule_spec_list_to_validate ) ) {
$this->remove_node( $node );
return;
}
// The remaining validations all have to do with attributes.
$attr_spec_list = array();
$tag_spec = array();
$cdata = array();
/*
* 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 = array();
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;
}
// 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 ) {
$spec_list = isset( $rule_spec_list_to_validate[ $id ][ AMP_Rule_Spec::ATTR_SPEC_LIST ] ) ? $rule_spec_list_to_validate[ $id ][ AMP_Rule_Spec::ATTR_SPEC_LIST ] : null;
if ( ! $this->is_missing_mandatory_attribute( $spec_list, $node ) ) {
$attr_spec_list = array_merge( $attr_spec_list, $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 ];
}
}
}
if ( ! empty( $attr_spec_list ) && $this->is_missing_mandatory_attribute( $attr_spec_list, $node ) ) {
$this->remove_node( $node );
return;
}
// Remove element if it has illegal CDATA.
if ( ! empty( $cdata ) && $node instanceof DOMElement ) {
$validity = $this->validate_cdata_for_node( $node, $cdata );
if ( is_wp_error( $validity ) ) {
$this->remove_node( $node );
return;
}
}
$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 ) . ')';
}
}
// Identify any remaining disallowed attributes.
$disallowed_attributes = $this->get_disallowed_attributes_in_node( $node, $merged_attr_spec_list );
// 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, $disallowed_attributes );
// If $disallowed_attributes is false then the entire element should be removed.
if ( false === $disallowed_attributes ) {
$this->remove_node( $node );
return;
}
// 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.
*/
$validation_error = array(
'element_attributes' => array(),
);
foreach ( $node->attributes as $attribute ) {
$validation_error['element_attributes'][ $attribute->nodeName ] = $attribute->nodeValue;
}
foreach ( $disallowed_attributes as $disallowed_attribute ) {
$this->remove_invalid_attribute( $node, $disallowed_attribute, $validation_error );
}
}
// Add required AMP component scripts if the element is still in the document.
if ( $node->parentNode ) {
if ( ! empty( $tag_spec['also_requires_tag_warning'] ) ) {
$this->script_components[] = strtok( $tag_spec['also_requires_tag_warning'][0], ' ' );
}
if ( ! empty( $tag_spec['requires_extension'] ) ) {
$this->script_components = array_merge( $this->script_components, $tag_spec['requires_extension'] );
}
// 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 ) {
$is_bind_attribute = (
'[' === $name[0]
||
( isset( $this->rev_alternate_attr_name_lookup[ $name ] ) && '[' === $this->rev_alternate_attr_name_lookup[ $name ][0] )
);
if ( $is_bind_attribute ) {
$this->script_components[] = 'amp-bind';
break;
}
}
}
}
}
/**
* 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 boolean $is_missing boolean Whether a required attribute is missing.
*/
public function is_missing_mandatory_attribute( $attr_spec, $node ) {
if ( ! is_array( $attr_spec ) ) {
return false;
}
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 ⚡.
}
$is_mandatory = isset( $attr_spec_rule_value[ AMP_Rule_Spec::MANDATORY ] ) ? ( true === $attr_spec_rule_value[ AMP_Rule_Spec::MANDATORY ] ) : false;
$attribute_exists = false;
if ( method_exists( $node, 'hasAttribute' ) ) {
$attribute_exists = $node->hasAttribute( $attr_name );
if ( ! $attribute_exists && ! empty( $attr_spec_rule_value[ AMP_Rule_Spec::ALTERNATIVE_NAMES ] ) ) {
foreach ( $attr_spec_rule_value[ AMP_Rule_Spec::ALTERNATIVE_NAMES ] as $alternative_attr_name ) {
if ( $node->hasAttribute( $alternative_attr_name ) ) {
$attribute_exists = true;
break;
}
}
}
}
if ( $is_mandatory && ! $attribute_exists ) {
return true;
}
}
return false;
}
/**
* Validate element for its CDATA.
*
* @since 0.7
*
* @param DOMElement $element Element.
* @param array $cdata_spec CDATA.
* @return true|WP_Error True when valid or error when invalid.
*/
private function validate_cdata_for_node( $element, $cdata_spec ) {
if ( isset( $cdata_spec['blacklisted_cdata_regex'] ) ) {
if ( preg_match( '@' . $cdata_spec['blacklisted_cdata_regex']['regex'] . '@u', $element->textContent ) ) {
return new WP_Error( $cdata_spec['blacklisted_cdata_regex']['error_message'] );
}
} 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 new WP_Error( 'cdata_regex' );
}
}
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.
*
* @since 0.5
*
* @param DOMNode $node The node to validate.
* @param array $tag_spec The specification.
* @return boolean $valid Whether the node's placement is valid.
*/
private function validate_tag_spec_for_node( $node, $tag_spec ) {
if ( ! empty( $tag_spec[ AMP_Rule_Spec::MANDATORY_PARENT ] ) && ! $this->has_parent( $node, $tag_spec[ AMP_Rule_Spec::MANDATORY_PARENT ] ) ) {
return false;
}
// Extension scripts must be in the head.
if ( isset( $tag_spec['extension_spec'] ) && ! $this->has_parent( $node, 'head' ) ) {
return false;
}
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 false;
}
}
}
if ( ! empty( $tag_spec[ AMP_Rule_Spec::MANDATORY_ANCESTOR ] ) && ! $this->has_ancestor( $node, $tag_spec[ AMP_Rule_Spec::MANDATORY_ANCESTOR ] ) ) {
return false;
}
return true;
}
/**
* Checks to see if a spec is potentially valid.
*
* Checks the given node based on the attributes present in the node.
*
* @note This can be a very expensive function. Use it sparingly.
*
* @param DOMNode $node Node.
* @param array[] $attr_spec_list Attribute Spec list.
*
* @return float Number of times the attribute spec list matched. If there was a mismatch, then 0 is returned. 0.5 is returned if there is an implicit match.
*/
private function validate_attr_spec_list_for_node( $node, $attr_spec_list ) {
/*
* If node has no attributes there is no point in continuing, but if none of attributes
* in the spec list are mandatory, then we give this a score.
*/
if ( ! $node->hasAttributes() ) {
foreach ( $attr_spec_list as $attr_name => $attr_spec_rule ) {
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::MANDATORY ] ) ) {
return 0;
}
}
return 0.5;
}
if ( ! $node instanceof DOMElement ) {
/*
* A DOMNode is not valid for checks so might
* as well bail here is not an DOMElement.
*/
return 0;
}
foreach ( $node->attributes as $attr_name => $attr_node ) {
if ( ! isset( $attr_spec_list[ $attr_name ][ AMP_Rule_Spec::ALTERNATIVE_NAMES ] ) ) {
continue;
}
foreach ( $attr_spec_list[ $attr_name ][ AMP_Rule_Spec::ALTERNATIVE_NAMES ] as $attr_alt_name ) {
$attr_spec_list[ $attr_alt_name ] = $attr_spec_list[ $attr_name ];
}
}
$score = 0;
/*
* Keep track of how many of the attribute spec rules are mandatory,
* because if none are mandatory, then we will let this rule have a
* score since all the invalid attributes can just be removed.
*/
$mandatory_count = 0;
/*
* Iterate through each attribute rule in this attr spec list and run
* the series of tests. Each filter is given a `$node`, an `$attr_name`,
* and an `$attr_spec_rule`. If the `$attr_spec_rule` seems to be valid
* for the given node, then the filter should increment the score by one.
*/
foreach ( $attr_spec_list as $attr_name => $attr_spec_rule ) {
// If attr spec rule is empty, then it allows anything.
if ( empty( $attr_spec_rule ) && $node->hasAttribute( $attr_name ) ) {
$score++;
continue;
}
// If a mandatory attribute is required, and attribute exists, pass.
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::MANDATORY ] ) ) {
$mandatory_count++;
$result = $this->check_attr_spec_rule_mandatory( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* Check 'value' - case sensitive
* Given attribute's value must exactly equal value of the rule to pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE ] ) ) {
$result = $this->check_attr_spec_rule_value( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* Check 'value_regex' - case sensitive regex match
* Given attribute's value must be a case insensitive match to regex pattern
* specified by the value of rule to pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_REGEX ] ) ) {
$result = $this->check_attr_spec_rule_value_regex( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* Check 'value_casei' - case insensitive
* Given attribute's value must be a case insensitive match to the value of
* the rule to pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_CASEI ] ) ) {
$result = $this->check_attr_spec_rule_value_casei( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* Check 'value_regex_casei' - case insensitive regex match
* Given attribute's value must be a case insensitive match to the regex
* pattern specified by the value of the rule to pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_REGEX_CASEI ] ) ) {
$result = $this->check_attr_spec_rule_value_regex_casei( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* If given attribute's value is a URL with a protocol, the protocol must
* be in the array specified by the rule's value to pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_URL ][ AMP_Rule_Spec::ALLOWED_PROTOCOL ] ) ) {
$result = $this->check_attr_spec_rule_allowed_protocol( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* If given attribute's value is a URL with a host, the host must
* be valid
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_URL ] ) ) {
$result = $this->check_attr_spec_rule_valid_url( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* If the given attribute's value is *not* a relative path, and the rule's
* value is `false`, then pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_URL ][ AMP_Rule_Spec::ALLOW_RELATIVE ] ) ) {
$result = $this->check_attr_spec_rule_disallowed_relative( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* If the given attribute's value exists, is non-empty and the rule's value
* is false, then pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_URL ][ AMP_Rule_Spec::ALLOW_EMPTY ] ) ) {
$result = $this->check_attr_spec_rule_disallowed_empty( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* If the given attribute's value is a URL and does not match any of the list
* of domains in the value of the rule, then pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::DISALLOWED_DOMAIN ] ) ) {
$result = $this->check_attr_spec_rule_disallowed_domain( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
/*
* If the attribute's value exists and does not match the regex specified
* by the rule's value, then pass.
*/
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::BLACKLISTED_VALUE_REGEX ] ) ) {
$result = $this->check_attr_spec_rule_blacklisted_value_regex( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
// If the attribute's value exists and it matches the value properties spec.
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_PROPERTIES ] ) && $node->hasAttribute( $attr_name ) ) {
$result = $this->check_attr_spec_rule_value_properties( $node, $attr_name, $attr_spec_rule );
if ( AMP_Rule_Spec::PASS === $result ) {
$score++;
} elseif ( AMP_Rule_Spec::FAIL === $result ) {
return 0;
}
}
}
// Give the spec a score if it doesn't have any mandatory attributes.
if ( 0 === $mandatory_count && 0 === $score ) {
$score = 0.5;
}
return $score;
}
/**
* Remove attributes from $node that are not listed in $allowed_attrs.
*
* @param DOMNode $node Node.
* @param array[] $attr_spec_list Attribute spec list.
* @return DOMAttr[] Attributes to remove.
*/
private function get_disallowed_attributes_in_node( $node, $attr_spec_list ) {
if ( ! $node instanceof DOMElement ) {
/**
* If $node is only a DOMNode and not a DOMElement we can't
* remove an attribute from it anyway. So bail out now.
*/
return array();
}
/*
* We can't remove attributes inside the 'foreach' loop without
* breaking the iteration. So we keep track of the attributes to
* remove in the first loop, then remove them in the second loop.
*/
$attrs_to_remove = array();
foreach ( $node->attributes as $attr_name => $attr_node ) {
if ( ! $this->is_amp_allowed_attribute( $attr_node, $attr_spec_list ) ) {
$attrs_to_remove[] = $attr_node;
}
}
return $attrs_to_remove;
}
/**
* Remove invalid AMP attributes values from $node that have been implicitly disallowed.
*
* Allowed values are found $this->globally_allowed_attributes and in parameter $attr_spec_list
*
* @param DOMNode $node Node.
* @param array[][] $attr_spec_list Attribute spec list.
* @param DOMAttr[] $attributes_pending_removal Attributes pending removal.
* @return DOMAttr[]|false Attributes to remove, or false if the element itself should be removed.
*/
private function sanitize_disallowed_attribute_values_in_node( $node, $attr_spec_list, $attributes_pending_removal ) {
if ( ! $node instanceof DOMElement ) {
/*
* If $node is only a DOMNode and not a DOMElement we can't
* remove an attribute from it anyway. So bail out now.
*/
return $attributes_pending_removal;
}
return $this->delegated_sanitize_disallowed_attribute_values_in_node(
$node,
array_merge(
$this->globally_allowed_attributes,
$attr_spec_list
),
$attributes_pending_removal
);
}
/**
* Remove attributes values from $node that have been disallowed by AMP.
*
* @see $this->sanitize_disallowed_attribute_values_in_node() which delegates to this method
*
* @param DOMElement $node Node.
* @param array[][] $attr_spec_list Attribute spec list.
* @param DOMAttr[] $attributes_pending_removal Attributes pending removal.
* @return DOMAttr[]|false Attributes to remove, or false if the element itself should be removed.
*/
private function delegated_sanitize_disallowed_attribute_values_in_node( $node, $attr_spec_list, $attributes_pending_removal ) {
$attrs_to_remove = array();
foreach ( $attr_spec_list as $attr_name => $attr_val ) {
if ( isset( $attr_spec_list[ $attr_name ][ AMP_Rule_Spec::ALTERNATIVE_NAMES ] ) ) {
foreach ( $attr_spec_list[ $attr_name ][ AMP_Rule_Spec::ALTERNATIVE_NAMES ] as $attr_alt_name ) {
$attr_spec_list[ $attr_alt_name ] = $attr_spec_list[ $attr_name ];
}
}
}
foreach ( $node->attributes as $attr_name => $attr_node ) {
if ( ! isset( $attr_spec_list[ $attr_name ] ) || in_array( $attr_node, $attributes_pending_removal, true ) ) {
continue;
}
$should_remove_node = false;
$attr_spec_rule = $attr_spec_list[ $attr_name ];
if ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE ] ) &&
AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_value( $node, $attr_name, $attr_spec_rule ) ) {
$should_remove_node = true;
} elseif ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_CASEI ] ) &&
AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_value_casei( $node, $attr_name, $attr_spec_rule ) ) {
$should_remove_node = true;
} elseif ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_REGEX ] ) &&
AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_value_regex( $node, $attr_name, $attr_spec_rule ) ) {
$should_remove_node = true;
} elseif ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_REGEX_CASEI ] ) &&
AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_value_regex_casei( $node, $attr_name, $attr_spec_rule ) ) {
$should_remove_node = true;
} elseif ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_URL ][ AMP_Rule_Spec::ALLOWED_PROTOCOL ] ) &&
AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_allowed_protocol( $node, $attr_name, $attr_spec_rule ) ) {
$should_remove_node = true;
} elseif ( isset( $attr_spec_rule[ AMP_Rule_Spec::VALUE_URL ] ) &&
AMP_Rule_Spec::FAIL === $this->check_attr_spec_rule_valid_url( $node, $attr_name, $attr_spec_rule ) ) {
$should_remove_node = true;