Use proper error pages instead of always redirecting

core/Controller/ErrorController.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2022 Julius Härtl <[email protected]>
+ *
+ * @author Julius Härtl <[email protected]>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Core\Controller;
+
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\TemplateResponse;
+
+class ErrorController extends \OCP\AppFramework\Controller {
+	/**
+	 * @PublicPage
+	 * @NoCSRFRequired
+	 */
+	public function error403(): TemplateResponse {
+		$response = new TemplateResponse(
+			'core',
+			'403',
+			[],
+			'error'
+		);
+		$response->setStatus(Http::STATUS_FORBIDDEN);
+		return $response;
+	}
+
+	/**
+	 * @PublicPage
+	 * @NoCSRFRequired
+	 */
+	public function error404(): TemplateResponse {
+		$response = new TemplateResponse(
+			'core',
+			'404',
+			[],
+			'error'
+		);
+		$response->setStatus(Http::STATUS_NOT_FOUND);
+		return $response;
+	}
+}

core/routes.php

@@ -97,6 +97,9 @@
 		['name' => 'WebAuthn#startAuthentication', 'url' => 'login/webauthn/start', 'verb' => 'POST'],
 		['name' => 'WebAuthn#finishAuthentication', 'url' => 'login/webauthn/finish', 'verb' => 'POST'],
 
+		['name' => 'Error#error404', 'url' => 'error/404'],
+		['name' => 'Error#error403', 'url' => 'error/403'],
+
 		// Well known requests https://tools.ietf.org/html/rfc5785
 		['name' => 'WellKnown#handle', 'url' => '.well-known/{service}'],
 

core/templates/404.php

@@ -17,8 +17,8 @@
 <?php else: ?>
 	<div class="body-login-container update">
 		<div class="icon-big icon-search"></div>
-		<h2><?php p($l->t('File not found')); ?></h2>
-		<p class="infogroup"><?php p($l->t('The document could not be found on the server. Maybe the share was deleted or has expired?')); ?></p>
+		<h2><?php p($l->t('Page not found')); ?></h2>
+		<p class="infogroup"><?php p($l->t('The page could not be found on the server.')); ?></p>
 		<p><a class="button primary" href="<?php p(\OC::$server->getURLGenerator()->linkTo('', 'index.php')) ?>">
 			<?php p($l->t('Back to %s', [$theme->getName()])); ?>
 		</a></p>

lib/base.php

@@ -72,6 +72,7 @@
 use OC\Files\Filesystem;
 use OC\Share20\Hooks;
 use OCP\User\Events\UserChangedEvent;
+use function OCP\Log\logger;
 
 require_once 'public/Constants.php';
 
@@ -1069,15 +1070,28 @@ public static function handleRequest() {
 			return;
 		}
 
-		// Someone is logged in
-		if (\OC::$server->getUserSession()->isLoggedIn()) {
-			OC_App::loadApps();
-			OC_User::setupBackends();
-			OC_Util::setupFS();
-			header('Location: ' . \OC::$server->getURLGenerator()->linkToDefaultPageUrl());
-		} else {
-			// Not handled and not logged in
-			header('Location: ' . \OC::$server->getURLGenerator()->linkToRouteAbsolute('core.login.showLoginForm'));
+		// Redirect to the default app or login only as an entry point
+		if ($requestPath === '') {
+			// Someone is logged in
+			if (\OC::$server->getUserSession()->isLoggedIn()) {
+				header('Location: ' . \OC::$server->getURLGenerator()->linkToDefaultPageUrl());
+			} else {
+				// Not handled and not logged in
+				header('Location: ' . \OC::$server->getURLGenerator()->linkToRouteAbsolute('core.login.showLoginForm'));
+			}
+			return;
+		}
+
+		try {
+			return OC::$server->get(\OC\Route\Router::class)->match('/error/404');
+		} catch (\Exception $e) {
+			logger('core')->emergency($e->getMessage(), ['exception' => $e]);
+			$l = \OC::$server->getL10N('lib');
+			OC_Template::printErrorPage(
+				$l->t('404'),
+				$l->t('The page could not be found on the server.'),
+				404
+			);
 		}
 	}
 

lib/composer/composer/autoload_classmap.php

@@ -976,6 +976,7 @@
     'OC\\Core\\Controller\\CollaborationResourcesController' => $baseDir . '/core/Controller/CollaborationResourcesController.php',
     'OC\\Core\\Controller\\ContactsMenuController' => $baseDir . '/core/Controller/ContactsMenuController.php',
     'OC\\Core\\Controller\\CssController' => $baseDir . '/core/Controller/CssController.php',
+    'OC\\Core\\Controller\\ErrorController' => $baseDir . '/core/Controller/ErrorController.php',
     'OC\\Core\\Controller\\GuestAvatarController' => $baseDir . '/core/Controller/GuestAvatarController.php',
     'OC\\Core\\Controller\\HoverCardController' => $baseDir . '/core/Controller/HoverCardController.php',
     'OC\\Core\\Controller\\JsController' => $baseDir . '/core/Controller/JsController.php',

lib/composer/composer/autoload_static.php

@@ -1009,6 +1009,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OC\\Core\\Controller\\CollaborationResourcesController' => __DIR__ . '/../../..' . '/core/Controller/CollaborationResourcesController.php',
         'OC\\Core\\Controller\\ContactsMenuController' => __DIR__ . '/../../..' . '/core/Controller/ContactsMenuController.php',
         'OC\\Core\\Controller\\CssController' => __DIR__ . '/../../..' . '/core/Controller/CssController.php',
+        'OC\\Core\\Controller\\ErrorController' => __DIR__ . '/../../..' . '/core/Controller/ErrorController.php',
         'OC\\Core\\Controller\\GuestAvatarController' => __DIR__ . '/../../..' . '/core/Controller/GuestAvatarController.php',
         'OC\\Core\\Controller\\HoverCardController' => __DIR__ . '/../../..' . '/core/Controller/HoverCardController.php',
         'OC\\Core\\Controller\\JsController' => __DIR__ . '/../../..' . '/core/Controller/JsController.php',

lib/private/Setup.php

@@ -509,10 +509,10 @@ public static function updateHtaccess() {
 		$htaccessContent = explode($content, $htaccessContent, 2)[0];
 
 		//custom 403 error page
-		$content .= "\nErrorDocument 403 " . $webRoot . '/';
+		$content .= "\nErrorDocument 403 " . $webRoot . '/index.php/error/403';
 
 		//custom 404 error page
-		$content .= "\nErrorDocument 404 " . $webRoot . '/';
+		$content .= "\nErrorDocument 404 " . $webRoot . '/index.php/error/404';
 
 		// Add rewrite rules if the RewriteBase is configured
 		$rewriteBase = $config->getValue('htaccess.RewriteBase', '');