<?php
/**
* The class handles adding of attributes to links to content.
*
* @since 1.0.43.2
* @package RankMath
* @subpackage RankMath\Frontend
* @author Rank Math <support@rankmath.com>
*/
namespace RankMath\Frontend;
use RankMath\Helper;
use RankMath\Traits\Hooker;
use RankMath\Helpers\Str;
use RankMath\Helpers\Url;
use RankMath\Helpers\HTML;
defined( 'ABSPATH' ) || exit;
/**
* Add Link_Attributes class.
*/
class Link_Attributes {
use Hooker;
/**
* Add rel=noopener or not.
*
* @var bool
*/
public $add_noopener;
/**
* Add rel=nofollow to links or not.
*
* @var bool
*/
public $nofollow_link;
/**
* Add rel=nofollow to images or not.
*
* @var bool
*/
public $nofollow_image;
/**
* Open links in a new window or not.
*
* @var bool
*/
public $new_window_link;
/**
* Remove existing CSS class from links or not.
*
* @var bool
*/
public $remove_class;
/**
* Check if the link attributes have been modified or not.
*
* @var bool
*/
public $is_dirty;
/**
* Additional attributes to add to links.
*
* @var array
*/
public $add_attributes;
/**
* The Constructor.
*/
public function __construct() {
$this->action( 'wp', 'add_attributes', 9999 );
$this->action( 'rest_api_init', 'add_attributes' );
}
/**
* Add nofollow, target, title and alt attributes to link and images.
*/
public function add_attributes() {
// Add rel="nofollow" & target="_blank" for external links.
$this->add_noopener = $this->do_filter( 'noopener', true );
$this->nofollow_link = Helper::get_settings( 'general.nofollow_external_links' );
$this->nofollow_image = Helper::get_settings( 'general.nofollow_image_links' );
$this->new_window_link = Helper::get_settings( 'general.new_window_external_links' );
$this->remove_class = $this->do_filter( 'link/remove_class', false );
$this->is_dirty = false;
// Filter to run the link attributes function even when Link options are disabled.
$this->add_attributes = $this->do_filter( 'link/add_attributes', $this->nofollow_link || $this->new_window_link || $this->nofollow_image || $this->add_noopener );
if ( $this->add_attributes || $this->remove_class ) {
$this->filter( 'the_content', 'add_link_attributes', 11 );
}
}
/**
* Add nofollow and target attributes to link.
*
* @param string $content Post content.
* @return string
*/
public function add_link_attributes( $content ) {
preg_match_all( '/<(a\s[^>]+)>/', $content, $matches );
if ( empty( $matches ) || empty( $matches[0] ) ) {
return $content;
}
foreach ( $matches[0] as $link ) {
$attrs = HTML::extract_attributes( $link );
if ( ! $this->can_add_attributes( $attrs ) ) {
continue;
}
$attrs = $this->remove_link_class( $attrs );
$attrs = $this->set_external_attrs( $attrs );
if ( $this->is_dirty ) {
$new = '<a' . HTML::attributes_to_string( $attrs ) . '>';
$content = str_replace( $link, $new, $content );
}
}
return $content;
}
/**
* Set rel attribute.
*
* @param array $attrs Array which hold rel attribute.
* @param string $property Property to add.
* @param boolean $append Append or not.
*/
private function set_rel_attribute( &$attrs, $property, $append ) {
if ( empty( $attrs['rel'] ) ) {
$attrs['rel'] = $property;
return;
}
if ( $append ) {
$attrs['rel'] .= ' ' . $property;
}
}
/**
* Check if we can do anything
*
* @param array $attrs Array of link attributes.
*
* @return boolean
*/
private function can_add_attributes( $attrs ) {
// If link has no href attribute or if the link is not valid then we don't need to do anything.
if (
empty( $attrs['href'] ) ||
( empty( wp_parse_url( $attrs['href'], PHP_URL_HOST ) ) && ! Url::is_affiliate( $attrs['href'] ) ) ||
( isset( $attrs['role'] ) && 'button' === $attrs['role'] )
) {
return false;
}
return true;
}
/**
* Remove rank-math-link class.
*
* @since 1.0.44.2
*
* @param array $attrs Array of link attributes.
*
* @return array $attrs
*/
private function remove_link_class( $attrs ) {
if ( ! $this->remove_class || empty( $attrs['class'] ) || strpos( $attrs['class'], 'rank-math-link' ) === false ) {
return $attrs;
}
$this->is_dirty = true;
$attrs['class'] = str_replace( 'rank-math-link', '', $attrs['class'] );
if ( ! trim( $attrs['class'] ) ) {
unset( $attrs['class'] );
}
return $attrs;
}
/**
* Set External attributs
*
* @since 1.0.44.2
*
* @param array $attrs Array of link attributes.
*
* @return array $attrs
*/
private function set_external_attrs( $attrs ) {
if ( ! $this->add_attributes ) {
return $attrs;
}
// Skip if there is no href or it's a hash link like "#id".
// Skip if relative link.
// Skip for same domain ignoring sub-domain if any.
if ( ! Url::is_external( $attrs['href'] ) ) {
return $attrs;
}
if ( $this->do_filter( 'nofollow/url', $this->should_add_nofollow( $attrs['href'] ), $attrs['href'] ) ) {
if ( $this->nofollow_link || ( $this->nofollow_image && $this->is_valid_image( $attrs['href'] ) ) ) {
$this->is_dirty = true;
$this->set_rel_attribute( $attrs, 'nofollow', ( isset( $attrs['rel'] ) && ! Str::contains( 'dofollow', $attrs['rel'] ) && ! Str::contains( 'nofollow', $attrs['rel'] ) ) );
}
}
if ( $this->new_window_link && ! isset( $attrs['target'] ) ) {
$this->is_dirty = true;
$attrs['target'] = '_blank';
}
if ( $this->add_noopener && $this->do_filter( 'noopener/domain', Url::get_domain( $attrs['href'] ) ) ) {
$this->is_dirty = true;
$this->set_rel_attribute( $attrs, 'noopener', ( isset( $attrs['rel'] ) && ! Str::contains( 'noopener', $attrs['rel'] ) ) );
}
if ( Url::is_affiliate( $attrs['href'] ) ) {
$this->is_dirty = true;
$this->set_rel_attribute( $attrs, 'sponsored', ( isset( $attrs['rel'] ) && ! Str::contains( 'sponsored', $attrs['rel'] ) ) );
}
return $attrs;
}
/**
* Check if we need to add nofollow for this link, based on "nofollow_domains" & "nofollow_exclude_domains"
*
* @param string $url Link URL.
* @return bool
*/
private function should_add_nofollow( $url ) {
if ( ! $this->nofollow_link && ! $this->nofollow_image ) {
return false;
}
$include_domains = $this->get_nofollow_domains( 'include' );
$exclude_domains = $this->get_nofollow_domains( 'exclude' );
$parent_domain = Url::get_domain( $url );
$parent_domain = preg_replace( '/^www\./', '', $parent_domain );
// Check if domain is in list.
if ( ! empty( $include_domains ) ) {
return in_array( $parent_domain, $include_domains, true );
}
// Check if domain is NOT in list.
if ( ! empty( $exclude_domains ) && in_array( $parent_domain, $exclude_domains, true ) ) {
return false;
}
return true;
}
/**
* Get domain for nofollow
*
* @param string $type Type either include or exclude.
* @return array
*/
private function get_nofollow_domains( $type ) {
static $rank_math_nofollow_domains;
if ( isset( $rank_math_nofollow_domains[ $type ] ) ) {
return $rank_math_nofollow_domains[ $type ];
}
$setting = 'include' === $type ? 'nofollow_domains' : 'nofollow_exclude_domains';
$domains = Helper::get_settings( "general.{$setting}" );
$domains = Str::to_arr_no_empty( $domains );
// Strip off www. prefixes.
$domains = array_map(
function( $domain ) {
$domain = preg_replace( '#^http(s)?://#', '', trim( $domain, '/' ) );
return preg_replace( '/^www\./', '', $domain );
},
$domains
);
$rank_math_nofollow_domains[ $type ] = $domains;
return $rank_math_nofollow_domains[ $type ];
}
/**
* Is a valid image url.
*
* @param string $url Image url.
*
* @return boolean
*/
private function is_valid_image( $url ) {
foreach ( [ '.jpg', '.jpeg', '.png', '.gif' ] as $ext ) {
if ( Str::contains( $ext, $url ) ) {
return true;
}
}
return false;
}
}