1 files changed, 193 insertions, 0 deletions
diff --git a/apps/dav/lib/Connector/Sabre/ZipFolderPlugin.php b/apps/dav/lib/Connector/Sabre/ZipFolderPlugin.php
new file mode 100644
index 00000000000..f198519b454
--- /dev/null
+++ b/apps/dav/lib/Connector/Sabre/ZipFolderPlugin.php
@@ -0,0 +1,193 @@
+<?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 OCA\DAV\Connector\Sabre\Exception\Forbidden;
+use OCP\EventDispatcher\IEventDispatcher;
+use OCP\Files\Events\BeforeZipCreatedEvent;
+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,
+		private IEventDispatcher $eventDispatcher,
+	) {
+	}
+
+	/**
+	 * 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);
+		// low priority to give any other afterMethod:* a chance to fire before we cancel everything
+		$this->server->on('afterMethod:GET', $this->afterDownload(...), 999);
+	}
+
+	/**
+	 * 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());
+
+		$mtime = $node->getMTime();
+		if ($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(), $mtime);
+		} elseif ($node instanceof NcFolder) {
+			$streamer->addEmptyDir($filename, $mtime);
+			$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 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)) {
+				$files = [$files];
+			}
+
+			foreach ($files as $file) {
+				if (!is_string($file)) {
+					// we log this as this means either we - or an app - have a bug somewhere or a user is trying invalid things
+					$this->logger->notice('Invalid files filter parameter for ZipFolderPlugin', ['filter' => $filesParam]);
+					// no valid parameter so continue with Sabre behavior
+					return null;
+				}
+			}
+		}
+
+		$folder = $node->getNode();
+		$event = new BeforeZipCreatedEvent($folder, $files);
+		$this->eventDispatcher->dispatchTyped($event);
+		if ((!$event->isSuccessful()) || $event->getErrorMessage() !== null) {
+			$errorMessage = $event->getErrorMessage();
+			if ($errorMessage === null) {
+				// Not allowed to download but also no explaining error
+				// so we abort the ZIP creation and fall back to Sabre default behavior.
+				return null;
+			}
+			// Downloading was denied by an app
+			throw new Forbidden($errorMessage);
+		}
+
+		$content = empty($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;
+	}
+
+	/**
+	 * Tell sabre/dav not to trigger it's own response sending logic as the handleDownload will have already send the response
+	 *
+	 * @return false|null
+	 */
+	public function afterDownload(Request $request, Response $response): ?bool {
+		$node = $this->tree->getNodeForPath($request->getPath());
+		if (!($node instanceof Directory)) {
+			// only handle directories
+			return null;
+		} else {
+			return false;
+		}
+	}
+}