1 files changed, 64 insertions, 0 deletions
diff --git a/apps/dav/lib/Connector/Sabre/AnonymousOptionsPlugin.php b/apps/dav/lib/Connector/Sabre/AnonymousOptionsPlugin.php
new file mode 100644
index 00000000000..0e2b1c58748
--- /dev/null
+++ b/apps/dav/lib/Connector/Sabre/AnonymousOptionsPlugin.php
@@ -0,0 +1,64 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\DAV\Connector\Sabre;
+
+use Sabre\DAV\CorePlugin;
+use Sabre\DAV\FS\Directory;
+use Sabre\DAV\ServerPlugin;
+use Sabre\DAV\Tree;
+use Sabre\HTTP\RequestInterface;
+use Sabre\HTTP\ResponseInterface;
+
+class AnonymousOptionsPlugin extends ServerPlugin {
+
+	/**
+	 * @var \Sabre\DAV\Server
+	 */
+	private $server;
+
+	/**
+	 * @param \Sabre\DAV\Server $server
+	 * @return void
+	 */
+	public function initialize(\Sabre\DAV\Server $server) {
+		$this->server = $server;
+		// before auth
+		$this->server->on('beforeMethod:*', [$this, 'handleAnonymousOptions'], 9);
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function isRequestInRoot($path) {
+		return $path === '' || (is_string($path) && !str_contains($path, '/'));
+	}
+
+	/**
+	 * @throws \Sabre\DAV\Exception\Forbidden
+	 * @return bool
+	 */
+	public function handleAnonymousOptions(RequestInterface $request, ResponseInterface $response) {
+		$isOffice = preg_match('/Microsoft Office/i', $request->getHeader('User-Agent') ?? '');
+		$emptyAuth = $request->getHeader('Authorization') === null
+			|| $request->getHeader('Authorization') === ''
+			|| trim($request->getHeader('Authorization')) === 'Bearer';
+		$isAnonymousOfficeOption = $request->getMethod() === 'OPTIONS' && $isOffice && $emptyAuth;
+		$isOfficeHead = $request->getMethod() === 'HEAD' && $isOffice && $emptyAuth;
+		if ($isAnonymousOfficeOption || $isOfficeHead) {
+			/** @var CorePlugin $corePlugin */
+			$corePlugin = $this->server->getPlugin('core');
+			// setup a fake tree for anonymous access
+			$this->server->tree = new Tree(new Directory(''));
+			$corePlugin->httpOptions($request, $response);
+			$this->server->emit('afterMethod:*', [$request, $response]);
+			$this->server->emit('afterMethod:OPTIONS', [$request, $response]);
+
+			$this->server->sapi->sendResponse($response);
+			return false;
+		}
+	}
+}