feat(dav): New `ZipFolderPlugin` which allows to download folders using GET requests

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

5 files changed, 167 insertions, 0 deletions

diff --git a/apps/dav/composer/composer/autoload_classmap.php b/apps/dav/composer/composer/autoload_classmap.php
index 4e59f50d8d7..2045c5e1fac 100644
--- a/apps/dav/composer/composer/autoload_classmap.php
+++ b/apps/dav/composer/composer/autoload_classmap.php
@@ -213,6 +213,7 @@ return array(
     'OCA\\DAV\\Connector\\Sabre\\SharesPlugin' => $baseDir . '/../lib/Connector/Sabre/SharesPlugin.php',
     'OCA\\DAV\\Connector\\Sabre\\TagList' => $baseDir . '/../lib/Connector/Sabre/TagList.php',
     'OCA\\DAV\\Connector\\Sabre\\TagsPlugin' => $baseDir . '/../lib/Connector/Sabre/TagsPlugin.php',
+    'OCA\\DAV\\Connector\\Sabre\\ZipFolderPlugin' => $baseDir . '/../lib/Connector/Sabre/ZipFolderPlugin.php',
     'OCA\\DAV\\Controller\\BirthdayCalendarController' => $baseDir . '/../lib/Controller/BirthdayCalendarController.php',
     'OCA\\DAV\\Controller\\DirectController' => $baseDir . '/../lib/Controller/DirectController.php',
     'OCA\\DAV\\Controller\\InvitationResponseController' => $baseDir . '/../lib/Controller/InvitationResponseController.php',
diff --git a/apps/dav/composer/composer/autoload_static.php b/apps/dav/composer/composer/autoload_static.php
index f241c660140..31f0974e8e3 100644
--- a/apps/dav/composer/composer/autoload_static.php
+++ b/apps/dav/composer/composer/autoload_static.php
@@ -228,6 +228,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\Connector\\Sabre\\SharesPlugin' => __DIR__ . '/..' . '/../lib/Connector/Sabre/SharesPlugin.php',
         'OCA\\DAV\\Connector\\Sabre\\TagList' => __DIR__ . '/..' . '/../lib/Connector/Sabre/TagList.php',
         'OCA\\DAV\\Connector\\Sabre\\TagsPlugin' => __DIR__ . '/..' . '/../lib/Connector/Sabre/TagsPlugin.php',
+        'OCA\\DAV\\Connector\\Sabre\\ZipFolderPlugin' => __DIR__ . '/..' . '/../lib/Connector/Sabre/ZipFolderPlugin.php',
         'OCA\\DAV\\Controller\\BirthdayCalendarController' => __DIR__ . '/..' . '/../lib/Controller/BirthdayCalendarController.php',
         'OCA\\DAV\\Controller\\DirectController' => __DIR__ . '/..' . '/../lib/Controller/DirectController.php',
         'OCA\\DAV\\Controller\\InvitationResponseController' => __DIR__ . '/..' . '/../lib/Controller/InvitationResponseController.php',
diff --git a/apps/dav/lib/Connector/Sabre/ServerFactory.php b/apps/dav/lib/Connector/Sabre/ServerFactory.php
index 53ce0ec3eee..4235a02831a 100644
--- a/apps/dav/lib/Connector/Sabre/ServerFactory.php
+++ b/apps/dav/lib/Connector/Sabre/ServerFactory.php
@@ -92,6 +92,11 @@ class ServerFactory {
 
 		$server->addPlugin(new RequestIdHeaderPlugin(\OC::$server->get(IRequest::class)));
 
+		$server->addPlugin(new ZipFolderPlugin(
+			$objectTree,
+			$this->logger,
+		));
+
 		// Some WebDAV clients do require Class 2 WebDAV support (locking), since
 		// we do not provide locking we emulate it using a fake locking plugin.
 		if ($this->request->isUserAgent([
diff --git a/apps/dav/lib/Connector/Sabre/ZipFolderPlugin.php b/apps/dav/lib/Connector/Sabre/ZipFolderPlugin.php
new file mode 100644
index 00000000000..a5820f80538
--- /dev/null
+++ b/apps/dav/lib/Connector/Sabre/ZipFolderPlugin.php
@@ -0,0 +1,155 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\DAV\Connector\Sabre;
+
+use OC\Streamer;
+use OCP\Files\File as NcFile;
+use OCP\Files\Folder as NcFolder;
+use OCP\Files\Node as NcNode;
+use Psr\Log\LoggerInterface;
+use Sabre\DAV\Server;
+use Sabre\DAV\ServerPlugin;
+use Sabre\DAV\Tree;
+use Sabre\HTTP\Request;
+use Sabre\HTTP\Response;
+
+/**
+ * This plugin allows to download folders accessed by GET HTTP requests on DAV.
+ * The WebDAV standard explicitly say that GET is not covered and should return what ever the application thinks would be a good representation.
+ *
+ * When a collection is accessed using GET, this will provide the content as a archive.
+ * The type can be set by the `Accept` header (MIME type of zip or tar), or as browser fallback using a `accept` GET parameter.
+ * It is also possible to only include some child nodes (from the collection it self) by providing a `filter` GET parameter or `X-NC-Files` custom header.
+ */
+class ZipFolderPlugin extends ServerPlugin {
+
+	/**
+	 * Reference to main server object
+	 */
+	private ?Server $server = null;
+
+	public function __construct(
+		private Tree $tree,
+		private LoggerInterface $logger,
+	) {
+	}
+
+	/**
+	 * This initializes the plugin.
+	 *
+	 * This function is called by \Sabre\DAV\Server, after
+	 * addPlugin is called.
+	 *
+	 * This method should set up the required event subscriptions.
+	 */
+	public function initialize(Server $server): void {
+		$this->server = $server;
+		$this->server->on('method:GET', $this->handleDownload(...), 100);
+	}
+
+	/**
+	 * Adding a node to the archive streamer.
+	 * This will recursively add new nodes to the stream if the node is a directory.
+	 */
+	protected function streamNode(Streamer $streamer, NcNode $node, string $rootPath): void {
+		// Remove the root path from the filename to make it relative to the requested folder
+		$filename = str_replace($rootPath, '', $node->getPath());
+
+		if ($node instanceof NcFile) {
+			$resource = $node->fopen('rb');
+			if ($resource === false) {
+				$this->logger->info('Cannot read file for zip stream', ['filePath' => $node->getPath()]);
+				throw new \Sabre\DAV\Exception\ServiceUnavailable('Requested file can currently not be accessed.');
+			}
+			$streamer->addFileFromStream($resource, $filename, $node->getSize(), $node->getMTime());
+		} elseif ($node instanceof NcFolder) {
+			$streamer->addEmptyDir($filename);
+			$content = $node->getDirectoryListing();
+			foreach ($content as $subNode) {
+				$this->streamNode($streamer, $subNode, $rootPath);
+			}
+		}
+	}
+
+	/**
+	 * Download a folder as an archive.
+	 * It is possible to filter / limit the files that should be downloaded,
+	 * either by passing (multiple) `X-NC-Files: the-file` headers
+	 * or by setting a `files=JSON_ARRAY_OF_FILES` URL query.
+	 *
+	 * @return false|null
+	 */
+	public function handleDownload(Request $request, Response $response): ?bool {
+		$node = $this->tree->getNodeForPath($request->getPath());
+		if (!($node instanceof \OCA\DAV\Connector\Sabre\Directory)) {
+			// only handle directories
+			return null;
+		}
+
+		$query = $request->getQueryParameters();
+
+		// Get accept header - or if set overwrite with accept GET-param
+		$accept = $request->getHeaderAsArray('Accept');
+		$acceptParam = $query['accept'] ?? '';
+		if ($acceptParam !== '') {
+			$accept = array_map(fn (string $name) => strtolower(trim($name)), explode(',', $acceptParam));
+		}
+		$zipRequest = !empty(array_intersect(['application/zip', 'zip'], $accept));
+		$tarRequest = !empty(array_intersect(['application/x-tar', 'tar'], $accept));
+		if (!$zipRequest && !$tarRequest) {
+			// does not accept zip or tar stream
+			return null;
+		}
+
+		$files = $request->getHeaderAsArray('X-NC-Files');
+		$filesParam = $query['files'] ?? '';
+		// The preferred way would be headers, but this is not possible for simple browser requests ("links")
+		// so we also need to support GET parameters
+		if ($filesParam !== '') {
+			$files = json_decode($filesParam);
+			if (!is_array($files)) {
+				if (!is_string($files)) {
+					// no valid parameter so continue with Sabre behavior
+					$this->logger->debug('Invalid files filter parameter for ZipFolderPlugin', ['filter' => $filesParam]);
+					return null;
+				}
+
+				$files = [$files];
+			}
+		}
+
+		$folder = $node->getNode();
+		$content = empty($files) ? $folder->getDirectoryListing() : [];
+		foreach ($files as $path) {
+			$child = $node->getChild($path);
+			assert($child instanceof Node);
+			$content[] = $child->getNode();
+		}
+
+		$archiveName = 'download';
+		$rootPath = $folder->getPath();
+		if (empty($files)) {
+			// We download the full folder so keep it in the tree
+			$rootPath = dirname($folder->getPath());
+			// Full folder is loaded to rename the archive to the folder name
+			$archiveName = $folder->getName();
+		}
+		$streamer = new Streamer($tarRequest, -1, count($content));
+		$streamer->sendHeaders($archiveName);
+		// For full folder downloads we also add the folder itself to the archive
+		if (empty($files)) {
+			$streamer->addEmptyDir($archiveName);
+		}
+		foreach ($content as $node) {
+			$this->streamNode($streamer, $node, $rootPath);
+		}
+		$streamer->finalize();
+		return false;
+	}
+}
diff --git a/apps/dav/lib/Server.php b/apps/dav/lib/Server.php
index daf180aec83..69f05395cb5 100644
--- a/apps/dav/lib/Server.php
+++ b/apps/dav/lib/Server.php
@@ -38,6 +38,7 @@ use OCA\DAV\Connector\Sabre\QuotaPlugin;
 use OCA\DAV\Connector\Sabre\RequestIdHeaderPlugin;
 use OCA\DAV\Connector\Sabre\SharesPlugin;
 use OCA\DAV\Connector\Sabre\TagsPlugin;
+use OCA\DAV\Connector\Sabre\ZipFolderPlugin;
 use OCA\DAV\DAV\CustomPropertiesBackend;
 use OCA\DAV\DAV\PublicAuth;
 use OCA\DAV\DAV\ViewOnlyPlugin;
@@ -209,6 +210,10 @@ class Server {
 		$this->server->addPlugin(new RequestIdHeaderPlugin(\OC::$server->get(IRequest::class)));
 		$this->server->addPlugin(new ChunkingV2Plugin(\OCP\Server::get(ICacheFactory::class)));
 		$this->server->addPlugin(new ChunkingPlugin());
+		$this->server->addPlugin(new ZipFolderPlugin(
+			$this->server->tree,
+			$logger,
+		));
 
 		// allow setup of additional plugins
 		$dispatcher->dispatch('OCA\DAV\Connector\Sabre::addPlugin', $event);