1 files changed, 119 insertions, 0 deletions
diff --git a/plugins/jetpack/class.frame-nonce-preview.php b/plugins/jetpack/class.frame-nonce-preview.php
new file mode 100644
index 00000000..19c0f220
--- /dev/null
+++ b/plugins/jetpack/class.frame-nonce-preview.php
@@ -0,0 +1,119 @@
+<?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' ) );
+		}
+
+		// autosave previews are validated differently
+		if ( isset( $_GET[ 'frame-nonce' ] ) && isset( $_GET[ 'preview_id' ] ) && isset( $_GET[ 'preview_nonce' ] ) ) {
+			remove_action( 'init', '_show_post_preview' );
+			add_action( 'init', array( $this, 'handle_autosave_nonce_validation' ) );
+		}
+	}
+
+	/**
+	 * 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;
+	}
+
+	/**
+	 * Handle validation for autosave preview request
+	 *
+	 * @since 4.7.0
+	 *
+	 */
+	public function handle_autosave_nonce_validation() {
+		if ( ! $this->is_frame_nonce_valid() ) {
+			wp_die( __( 'Sorry, you are not allowed to preview drafts.', 'jetpack' ) );
+		}
+		add_filter( 'the_preview', '_set_preview' );
+	}
+}
+
+Jetpack_Frame_Nonce_Preview::get_instance();