Customizer: Refresh nonces when a session expires and the user logs in again.

This was broken since 4.0 and the introduction of user session tokens. The nonces are now tied to session tokens as opposed to user IDs, and thus they change with each re-login.
Custom nonces can be added through the `customize_refresh_nonces` filter. On a successful refresh request the JavaScript API will trigger a `nonce-refresh` event. See widget's update nonce as an example.

props westonruter for initial patch.
fixes #31294.

git-svn-id: https://develop.svn.wordpress.org/trunk@32054 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/js/customize-controls.js

@@ -2358,11 +2358,23 @@
 
 			messenger.targetWindow( iframe[0].contentWindow );
 
-			messenger.bind( 'login', function() {
-				iframe.remove();
-				messenger.destroy();
-				delete previewer._login;
-				deferred.resolve();
+			messenger.bind( 'login', function () {
+				var refreshNonces = previewer.refreshNonces();
+
+				refreshNonces.always( function() {
+					iframe.remove();
+					messenger.destroy();
+					delete previewer._login;
+				});
+
+				refreshNonces.done( function() {
+					deferred.resolve();
+				});
+
+				refreshNonces.fail( function() {
+					previewer.cheatin();
+					deferred.reject();
+				});
 			});
 
 			return this._login;
@@ -2370,6 +2382,28 @@
 
 		cheatin: function() {
 			$( document.body ).empty().addClass('cheatin').append( '<p>' + api.l10n.cheatin + '</p>' );
+		},
+
+		refreshNonces: function() {
+			var request, deferred = $.Deferred();
+
+			deferred.promise();
+
+			request = wp.ajax.post( 'customize_refresh_nonces', {
+				wp_customize: 'on',
+				theme: api.settings.theme.stylesheet
+			});
+
+			request.done( function( response ) {
+				api.trigger( 'nonce-refresh', response );
+				deferred.resolve();
+			});
+
+			request.fail( function() {
+				deferred.reject();
+			});
+
+			return deferred;
 		}
 	});
 
@@ -2538,6 +2572,12 @@
 			$.extend( this.nonce, nonce );
 		});
 
+		// Refresh the nonces if login sends updated nonces over.
+		api.bind( 'nonce-refresh', function( nonce ) {
+			$.extend( api.settings.nonce, nonce );
+			$.extend( api.previewer.nonce, nonce );
+		});
+
 		// Create Settings
 		$.each( api.settings.settings, function( id, data ) {
 			api.create( id, id, data.value, {

src/wp-admin/js/customize-widgets.js

@@ -1898,6 +1898,11 @@
 		sidebar_widgets: api.Widgets.SidebarControl
 	});
 
+	// Refresh the nonce if login sends updated nonces over.
+	api.bind( 'nonce-refresh', function( nonces ) {
+		api.Widgets.data.nonce = nonces['update-widget'];
+	});
+
 	/**
 	 * Init Customizer for widgets.
 	 */

src/wp-includes/class-wp-customize-manager.php

@@ -91,8 +91,8 @@ final class WP_Customize_Manager {
 
 		add_filter( 'wp_die_handler', array( $this, 'wp_die_handler' ) );
 
-		add_action( 'setup_theme',  array( $this, 'setup_theme' ) );
-		add_action( 'wp_loaded',    array( $this, 'wp_loaded' ) );
+		add_action( 'setup_theme', array( $this, 'setup_theme' ) );
+		add_action( 'wp_loaded',   array( $this, 'wp_loaded' ) );
 
 		// Run wp_redirect_status late to make sure we override the status last.
 		add_action( 'wp_redirect_status', array( $this, 'wp_redirect_status' ), 1000 );
@@ -105,7 +105,8 @@ final class WP_Customize_Manager {
 		remove_action( 'admin_init', '_maybe_update_plugins' );
 		remove_action( 'admin_init', '_maybe_update_themes' );
 
-		add_action( 'wp_ajax_customize_save', array( $this, 'save' ) );
+		add_action( 'wp_ajax_customize_save',           array( $this, 'save' ) );
+		add_action( 'wp_ajax_customize_refresh_nonces', array( $this, 'refresh_nonces' ) );
 
 		add_action( 'customize_register',                 array( $this, 'register_controls' ) );
 		add_action( 'customize_register',                 array( $this, 'register_dynamic_settings' ), 11 ); // allow code to create settings first
@@ -783,6 +784,34 @@ final class WP_Customize_Manager {
 		wp_send_json_success( $response );
 	}
 
+	/**
+	 * Refresh nonces for the current preview.
+	 *
+	 * @since 4.2.0
+	 */
+	public function refresh_nonces() {
+		if ( ! $this->is_preview() ) {
+			wp_send_json_error( 'not_preview' );
+		}
+
+		$nonces = array(
+			'save'    => wp_create_nonce( 'save-customize_' . $this->get_stylesheet() ),
+			'preview' => wp_create_nonce( 'preview-customize_' . $this->get_stylesheet() ),
+		);
+
+		/**
+		 * Filter nonces for a customize_refresh_nonces AJAX request.
+		 *
+		 * @since 4.2.0
+		 *
+		 * @param array                $nonces Array of refreshed nonces for save and
+		 *                                     preview actions.
+		 * @param WP_Customize_Manager $this   WP_Customize_Manager instance.
+		 */
+		$nonces = apply_filters( 'customize_refresh_nonces', $nonces, $this );
+		wp_send_json_success( $nonces );
+	}
+
 	/**
 	 * Add a customize setting.
 	 *

src/wp-includes/class-wp-customize-widgets.php

@@ -95,6 +95,7 @@ final class WP_Customize_Widgets {
 		add_action( 'customize_controls_print_footer_scripts', array( $this, 'print_footer_scripts' ) );
 		add_action( 'customize_controls_print_footer_scripts', array( $this, 'output_widget_control_templates' ) );
 		add_action( 'customize_preview_init',                  array( $this, 'customize_preview_init' ) );
+		add_filter( 'customize_refresh_nonces',                array( $this, 'refresh_nonces' ) );
 
 		add_action( 'dynamic_sidebar',                         array( $this, 'tally_rendered_widgets' ) );
 		add_filter( 'is_active_sidebar',                       array( $this, 'tally_sidebars_via_is_active_sidebar_calls' ), 10, 2 );
@@ -888,6 +889,20 @@ final class WP_Customize_Widgets {
 		add_action( 'wp_footer',          array( $this, 'export_preview_data' ), 20 );
 	}
 
+	/**
+	 * Refresh nonce for widget updates.
+	 *
+	 * @since 4.2.0
+	 * @access public
+	 *
+	 * @param  array $nonces Array of nonces.
+	 * @return array $nonces Array of nonces.
+	 */
+	public function refresh_nonces( $nonces ) {
+		$nonces['update-widget'] = wp_create_nonce( 'update-widget' );
+		return $nonces;
+	}
+
 	/**
 	 * When previewing, make sure the proper previewing widgets are used.
 	 *