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A new class file which will override Blacklist Sanitizer
<?php
$amp_blacklist_sanitizer = realpath( AMP__VENDOR__DIR__ . '/includes/sanitizers/class-amp-blacklist-sanitizer.php' );
if ( $amp_blacklist_sanitizer ) {
include_once $amp_blacklist_sanitizer;
}
if ( class_exists( 'AMPforWP\\AMPVendor\\AMP_Blacklist_Sanitizer' ) ) {
class AMP_New_Blacklist extends AMPforWP\AMPVendor\AMP_Blacklist_Sanitizer {
const PATTERN_REL_WP_ATTACHMENT = '#wp-att-([\d]+)#';
protected $DEFAULT_ARGS = array(
'add_blacklisted_protocols' => array(),
'add_blacklisted_tags' => array(),
'add_blacklisted_attributes' => array(),
);
public function sanitize() {
$blacklisted_tags = $this->get_blacklisted_tags();
$blacklisted_attributes = $this->get_blacklisted_attributes();
$blacklisted_protocols = $this->get_blacklisted_protocols();
$body = $this->get_body_node();
$this->strip_tags( $body, $blacklisted_tags );
$this->strip_attributes_recursive( $body, $blacklisted_attributes, $blacklisted_protocols );
}
private function strip_attributes_recursive( $node, $bad_attributes, $bad_protocols ) {
if ( $node->nodeType !== XML_ELEMENT_NODE ) {
return;
}
$node_name = $node->nodeName;
// Some nodes may contain valid content but are themselves invalid.
// Remove the node but preserve the children.
if ( 'font' === $node_name ) {
$this->replace_node_with_children( $node, $bad_attributes, $bad_protocols );
return;
} elseif ( 'a' === $node_name && false === $this->validate_a_node( $node ) ) {
$this->replace_node_with_children( $node, $bad_attributes, $bad_protocols );
return;
}
if ( $node->hasAttributes() ) {
$length = $node->attributes->length;
for ( $i = $length - 1; $i >= 0; $i-- ) {
$attribute = $node->attributes->item( $i );
$attribute_name = strtolower( $attribute->name );
if ( in_array( $attribute_name, $bad_attributes ) ) {
$node->removeAttribute( $attribute_name );
continue;
}
// on* attributes (like onclick) are a special case
if ( 0 === stripos( $attribute_name, 'on' ) && $attribute_name != 'on' ) {
$node->removeAttribute( $attribute_name );
continue;
} elseif ( 'a' === $node_name ) {
$this->sanitize_a_attribute( $node, $attribute );
}
}
}
$length = $node->childNodes->length;
for ( $i = $length - 1; $i >= 0; $i-- ) {
$child_node = $node->childNodes->item( $i );
$this->strip_attributes_recursive( $child_node, $bad_attributes, $bad_protocols );
}
}
private function strip_tags( $node, $tag_names ) {
foreach ( $tag_names as $tag_name ) {
$elements = $node->getElementsByTagName( $tag_name );
$length = $elements->length;
if ( 0 === $length ) {
continue;
}
for ( $i = $length - 1; $i >= 0; $i-- ) {
$element = $elements->item( $i );
$parent_node = $element->parentNode;
$parent_node->removeChild( $element );
if ( 'body' !== $parent_node->nodeName && AMP_DOM_Utils::is_node_empty( $parent_node ) ) {
$parent_node->parentNode->removeChild( $parent_node );
}
}
}
}
private function sanitize_a_attribute( $node, $attribute ) {
$attribute_name = strtolower( $attribute->name );
if ( 'rel' === $attribute_name ) {
$old_value = $attribute->value;
$new_value = trim( preg_replace( self::PATTERN_REL_WP_ATTACHMENT, '', $old_value ) );
if ( empty( $new_value ) ) {
$node->removeAttribute( $attribute_name );
} elseif ( $old_value !== $new_value ) {
$node->setAttribute( $attribute_name, $new_value );
}
} elseif ( 'rev' === $attribute_name ) {
// rev removed from HTML5 spec, which was used by Jetpack Markdown.
$node->removeAttribute( $attribute_name );
} elseif ( 'target' === $attribute_name ) {
// _blank is the only allowed value and it must be lowercase.
// replace _new with _blank and others should simply be removed.
$old_value = strtolower( $attribute->value );
if ( '_blank' === $old_value || '_new' === $old_value ) {
// _new is not allowed; swap with _blank
$node->setAttribute( $attribute_name, '_blank' );
} else {
// only _blank is allowed
$node->removeAttribute( $attribute_name );
}
}
}
private function validate_a_node( $node ) {
// Get the href attribute
$href = $node->getAttribute( 'href' );
// If no href is set and this isn't an anchor, it's invalid
if ( empty( $href ) ) {
$name_attr = $node->getAttribute( 'name' );
if ( ! empty( $name_attr ) ) {
// No further validation is required
return true;
} else {
return false;
}
}
// If this is an anchor link, just return true
if ( 0 === strpos( $href, '#' ) ) {
return true;
}
// If the href starts with a '/', append the home_url to it for validation purposes.
if ( 0 === stripos( $href, '/' ) ) {
$href = untrailingslashit( get_home_url() ) . $href;
}
$valid_protocols = array( 'http', 'https', 'mailto', 'sms', 'tel', 'viber', 'whatsapp' );
$special_protocols = array( 'tel', 'sms' ); // these ones don't valid with `filter_var+FILTER_VALIDATE_URL`
$protocol = strtok( $href, ':' );
if ( false === filter_var( $href, FILTER_VALIDATE_URL )
&& ! in_array( $protocol, $special_protocols ) ) {
return false;
}
if ( ! in_array( $protocol, $valid_protocols ) ) {
return false;
}
return true;
}
private function replace_node_with_children( $node, $bad_attributes, $bad_protocols ) {
// If the node has children and also has a parent node,
// clone and re-add all the children just before current node.
if ( $node->hasChildNodes() && $node->parentNode ) {
foreach ( $node->childNodes as $child_node ) {
$new_child = $child_node->cloneNode( true );
$this->strip_attributes_recursive( $new_child, $bad_attributes, $bad_protocols );
$node->parentNode->insertBefore( $new_child, $node );
}
}
// Remove the node from the parent, if defined.
if ( $node->parentNode ) {
$node->parentNode->removeChild( $node );
}
}
private function merge_defaults_with_args( $key, $values ) {
// Merge default values with user specified args
if ( ! empty( $this->args[ $key ] )
&& is_array( $this->args[ $key ] ) ) {
$values = array_merge( $values, $this->args[ $key ] );
}
return $values;
}
private function get_blacklisted_protocols() {
return $this->merge_defaults_with_args( 'add_blacklisted_protocols', array(
'javascript',
) );
}
private function get_blacklisted_tags() {
return $this->merge_defaults_with_args( 'add_blacklisted_tags', array(
'script',
'noscript',
'style',
'frame',
'frameset',
'object',
'param',
'applet',
// Removed this form elements to make sure
// Form works in AMP
// 'form',
// 'label',
// 'input',
// 'textarea',
// 'select',
// 'option',
'link',
'picture',
// Sanitizers run after embed handlers, so if anything wasn't matched, it needs to be removed.
'embed',
'embedvideo',
// Other weird ones
'comments-count',
// These are converted into amp-* versions
//'img',
//'video',
//'audio',
//'iframe',
) );
}
private function get_blacklisted_attributes() {
return $this->merge_defaults_with_args( 'add_blacklisted_attributes', array(
'style',
'size',
'clear',
'align',
'valign',
) );
}
}
}
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