[Service Worker] Support redirects to relative URLs in Safari (#1978)

packages/php-wasm/node-polyfills/src/index.ts

@@ -1,2 +1,3 @@
 import './lib/blob';
 import './lib/custom-event';
+import './lib/url';

packages/php-wasm/node-polyfills/src/lib/url.ts

@@ -0,0 +1,23 @@
+import { currentJsRuntime } from './current-js-runtime';
+
+if (currentJsRuntime === 'NODE') {
+	/**
+	 * Polyfill for URL.canParse if it's missing.
+	 *
+	 * URL.canParse is available since Node 19.9.0,
+	 * but Playground currently uses Node 18.18.0.
+	 *
+	 * This implementation is based on the one from `core-js`
+	 * by Denis Pushkarev, https://github.com/zloirock
+	 * https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/web.url.can-parse.js
+	 */
+	if (typeof URL.canParse !== 'function') {
+		globalThis.URL.canParse = function (url: string) {
+			try {
+				return !!new URL(url);
+			} catch (e) {
+				return false;
+			}
+		};
+	}
+}

packages/php-wasm/universal/src/lib/php-request-handler.ts

@@ -318,9 +318,7 @@ export class PHPRequestHandler {
 	 * @param  request - PHP Request data.
 	 */
 	async request(request: PHPRequest): Promise<PHPResponse> {
-		const isAbsolute =
-			request.url.startsWith('http://') ||
-			request.url.startsWith('https://');
+		const isAbsolute = URL.canParse(request.url);
 		const requestedUrl = new URL(
 			// Remove the hash part of the URL as it's not meant for the server.
 			request.url.split('#')[0],

packages/php-wasm/web-service-worker/src/utils.ts

@@ -63,6 +63,31 @@ export async function convertFetchEventToPHPRequest(event: FetchEvent) {
 		throw e;
 	}
 
+	/**
+	 * Safari has a bug that prevents Service Workers from redirecting relative URLs.
+	 * When attempting to redirect to a relative URL, the network request will return an error.
+	 * See the Webkit bug for details: https://bugs.webkit.org/show_bug.cgi?id=282427.
+	 *
+	 * Because PHP and WordPress can redirect to both relative and absolute URLs
+	 * using the `location` header we need to ensure redirects are processed
+	 * correctly by the Service Worker.
+	 *
+	 * As a workaround for Safari Service Workers, we use `Response.redirect()`
+	 * for all redirect responses (300-399 status codes) coming from PHP.
+	 * This solution was suggested in the Webkit bug comment:
+	 * https://bugs.webkit.org/show_bug.cgi?id=282427#c2
+	 */
+	if (
+		phpResponse.httpStatusCode >= 300 &&
+		phpResponse.httpStatusCode <= 399 &&
+		phpResponse.headers['location']
+	) {
+		return Response.redirect(
+			phpResponse.headers['location'][0],
+			phpResponse.httpStatusCode
+		);
+	}
+
 	return new Response(phpResponse.bytes, {
 		headers: phpResponse.headers,
 		status: phpResponse.httpStatusCode,

packages/playground/wordpress/src/index.ts

@@ -160,19 +160,9 @@ export async function setupPlatformLevelMuPlugins(php: UniversalPHP) {
 			 * Reload page to ensure the user is logged in correctly.
 			 * WordPress uses cookies to determine if the user is logged in,
 			 * so we need to reload the page to ensure the cookies are set.
-			 *
-			 * Both WordPress home url and REQUEST_URI may include the site scope
-			 * subdirectory.
-			 * To prevent the redirect from including two scopes, we need to
-			 * remove the scope from the REQUEST_URI if it's present.
 			 */
-			$redirect_url = $_SERVER['REQUEST_URI'];
-			if (strpos($redirect_url, '/scope:') === 0) {
-				$parts = explode('/', $redirect_url);
-				$redirect_url = '/' . implode('/', array_slice($parts, 2));
-			}
 			wp_redirect(
-				home_url($redirect_url),
+				$_SERVER['REQUEST_URI'],
 				302
 			);
 			exit;