1 files changed, 113 insertions, 0 deletions
diff --git a/lib/private/OCS/DiscoveryService.php b/lib/private/OCS/DiscoveryService.php
new file mode 100644
index 00000000000..85686e59b02
--- /dev/null
+++ b/lib/private/OCS/DiscoveryService.php
@@ -0,0 +1,113 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2017 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\OCS;
+
+use OCP\AppFramework\Http;
+use OCP\Http\Client\IClient;
+use OCP\Http\Client\IClientService;
+use OCP\ICache;
+use OCP\ICacheFactory;
+use OCP\OCS\IDiscoveryService;
+
+class DiscoveryService implements IDiscoveryService {
+	/** @var ICache */
+	private ICache $cache;
+
+	/** @var IClient */
+	private IClient $client;
+
+	/**
+	 * @param ICacheFactory $cacheFactory
+	 * @param IClientService $clientService
+	 */
+	public function __construct(ICacheFactory $cacheFactory,
+		IClientService $clientService,
+	) {
+		$this->cache = $cacheFactory->createDistributed('ocs-discovery');
+		$this->client = $clientService->newClient();
+	}
+
+
+	/**
+	 * Discover OCS end-points
+	 *
+	 * If no valid discovery data is found the defaults are returned
+	 *
+	 * @param string $remote
+	 * @param string $service the service you want to discover
+	 * @param bool $skipCache We won't check if the data is in the cache. This is useful if a background job is updating the status
+	 * @return array
+	 */
+	public function discover(string $remote, string $service, bool $skipCache = false): array {
+		// Check the cache first
+		if ($skipCache === false) {
+			$cacheData = $this->cache->get($remote . '#' . $service);
+			if ($cacheData) {
+				$data = json_decode($cacheData, true);
+				if (\is_array($data)) {
+					return $data;
+				}
+			}
+		}
+
+		$discoveredServices = [];
+
+		// query the remote server for available services
+		try {
+			$response = $this->client->get($remote . '/ocs-provider/', [
+				'timeout' => 10,
+				'connect_timeout' => 10,
+			]);
+			if ($response->getStatusCode() === Http::STATUS_OK) {
+				$decodedServices = json_decode($response->getBody(), true);
+				if (\is_array($decodedServices)) {
+					$discoveredServices = $this->getEndpoints($decodedServices, $service);
+				}
+			}
+		} catch (\Exception $e) {
+			// if we couldn't discover the service or any end-points we return a empty array
+		}
+
+		// Write into cache
+		$this->cache->set($remote . '#' . $service, json_encode($discoveredServices), 60 * 60 * 24);
+		return $discoveredServices;
+	}
+
+	/**
+	 * get requested end-points from the requested service
+	 *
+	 * @param array $decodedServices
+	 * @param string $service
+	 * @return array
+	 */
+	protected function getEndpoints(array $decodedServices, string $service): array {
+		$discoveredServices = [];
+
+		if (isset($decodedServices['services'][$service]['endpoints'])) {
+			foreach ($decodedServices['services'][$service]['endpoints'] as $endpoint => $url) {
+				if ($this->isSafeUrl($url)) {
+					$discoveredServices[$endpoint] = $url;
+				}
+			}
+		}
+
+		return $discoveredServices;
+	}
+
+	/**
+	 * Returns whether the specified URL includes only safe characters, if not
+	 * returns false
+	 *
+	 * @param string $url
+	 * @return bool
+	 */
+	protected function isSafeUrl(string $url): bool {
+		return (bool)preg_match('/^[\/\.\-A-Za-z0-9]+$/', $url);
+	}
+}