<?php
/**
* Allows viewing posts on the frontend when the user is not logged in.
*/
class Jetpack_Frame_Nonce_Preview {
static $instance = null;
/**
* Returns the single instance of the Jetpack_Frame_Nonce_Preview object
*
* @since 4.3.0
*
* @return Jetpack_Frame_Nonce_Preview
**/
public static function get_instance() {
if ( ! is_null( self::$instance ) ) {
return self::$instance;
}
return self::$instance = new Jetpack_Frame_Nonce_Preview();
}
function __construct() {
if ( isset( $_GET['frame-nonce'] ) && ! is_admin() ) {
add_filter( 'pre_get_posts', array( $this, 'maybe_display_post' ) );
}
}
/**
* Verify that frame nonce exists, and if so, validate the nonce by calling WP.com.
*
* @since 4.3.0
*
* @return bool
*/
public function is_frame_nonce_valid() {
if ( empty( $_GET[ 'frame-nonce' ] ) ) {
return false;
}
Jetpack::load_xml_rpc_client();
$xml = new Jetpack_IXR_Client();
$xml->query( 'jetpack.verifyFrameNonce', sanitize_key( $_GET['frame-nonce'] ) );
if ( $xml->isError() ) {
return false;
}
return (bool) $xml->getResponse();
}
/**
* Conditionally add a hook on posts_results if this is the main query, a preview, and singular.
*
* @since 4.3.0
*
* @param WP_Query $query
*
* @return WP_Query
*/
public function maybe_display_post( $query ) {
if (
$query->is_main_query() &&
$query->is_preview() &&
$query->is_singular()
) {
add_filter( 'posts_results', array( $this, 'set_post_to_publish' ), 10, 2 );
}
return $query;
}
/**
* Conditionally set the first post to 'publish' if the frame nonce is valid and there is a post.
*
* @since 4.3.0
*
* @param array $posts
*
* @return array
*/
public function set_post_to_publish( $posts ) {
remove_filter( 'posts_results', array( $this, 'set_post_to_publish' ), 10, 2 );
if ( empty( $posts ) || is_user_logged_in() || ! $this->is_frame_nonce_valid() ) {
return $posts;
}
$posts[0]->post_status = 'publish';
// Disable comments and pings for this post.
add_filter( 'comments_open', '__return_false' );
add_filter( 'pings_open', '__return_false' );
return $posts;
}
}
Jetpack_Frame_Nonce_Preview::get_instance();