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typo3/sysext/backend/Classes/Middleware/LockedBackendGuard.php

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+<?php
+declare(strict_types = 1);
+namespace TYPO3\CMS\Backend\Middleware;
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use TYPO3\CMS\Backend\Exception\BackendLockedException;
+use TYPO3\CMS\Core\Core\Environment;
+use TYPO3\CMS\Core\Http\JsonResponse;
+use TYPO3\CMS\Core\Http\RedirectResponse;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+
+/**
+ * Checks various security options for accessing the TYPO3 backend before proceeding
+ *
+ * Depends on the NormalizedParams middleware to identify the
+ * Site URL and if the page is not running via HTTPS yet.
+ *
+ * @internal
+ */
+class LockedBackendGuard implements MiddlewareInterface
+{
+    /**
+     * Checks the client's IP address and if typo3conf/LOCK_BACKEND is available
+     *
+     * @param ServerRequestInterface $request
+     * @param RequestHandlerInterface $handler
+     * @return ResponseInterface
+     */
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        try {
+            $redirectToUri = $this->checkLockedBackend();
+            if (!empty($redirectToUri)) {
+                return new RedirectResponse($redirectToUri, 302);
+            }
+        } catch (BackendLockedException $e) {
+            // Looks like an AJAX request that can handle JSON, (usually from the timeout functionality)
+            // So, let's form a request that fits
+            if (strpos($request->getHeaderLine('Accept'), 'application/json') !== false) {
+                $session = [
+                    'timed_out' => false,
+                    'will_time_out' => false,
+                    'locked' => true,
+                    'message' => $e->getMessage()
+                ];
+                return new JsonResponse(['login' => $session]);
+            }
+            throw $e;
+        }
+        $this->validateVisitorsIpAgainstIpMaskList(
+            $request->getAttribute('normalizedParams')->getRemoteAddress(),
+            trim((string)$GLOBALS['TYPO3_CONF_VARS']['BE']['IPmaskList'])
+        );
+
+        return $handler->handle($request);
+    }
+
+    /**
+     * Check adminOnly configuration variable and redirects to an URL in file typo3conf/LOCK_BACKEND
+     *
+     * @return string|null
+     * @throws BackendLockedException
+     */
+    protected function checkLockedBackend()
+    {
+        if ($GLOBALS['TYPO3_CONF_VARS']['BE']['adminOnly'] < 0) {
+            throw new BackendLockedException('TYPO3 Backend locked: Backend and Install Tool are locked for maintenance. [BE][adminOnly] is set to "' . (int)$GLOBALS['TYPO3_CONF_VARS']['BE']['adminOnly'] . '".', 1517949794);
+        }
+        if (@is_file(Environment::getLegacyConfigPath() . '/LOCK_BACKEND')) {
+            $fileContent = file_get_contents(Environment::getLegacyConfigPath() . '/LOCK_BACKEND');
+            if ($fileContent) {
+                return $fileContent;
+            }
+            throw new BackendLockedException('TYPO3 Backend locked: Browser backend is locked for maintenance. Remove lock by removing the file "typo3conf/LOCK_BACKEND" or use CLI-scripts.', 1517949793);
+        }
+    }
+
+    /**
+     * Compare client IP with IPmaskList and throw an exception
+     *
+     * @param string $ipAddress
+     * @param string $ipMaskList
+     * @throws \RuntimeException
+     */
+    protected function validateVisitorsIpAgainstIpMaskList(string $ipAddress, string $ipMaskList = '')
+    {
+        if ($ipMaskList !== '' && !GeneralUtility::cmpIP($ipAddress, $ipMaskList)) {
+            throw new \RuntimeException('TYPO3 Backend access denied: The IP address of your client does not match the list of allowed IP addresses.', 1517949792);
+        }
+    }
+}