From 5f3abffe6f37b4f8639fde8bcaf35d873a17636c Mon Sep 17 00:00:00 2001
From: Lukas Reschke <lukas@statuscode.ch>
Date: Tue, 23 Mar 2021 16:41:31 +0000
Subject: Improve networking checks

Whilst we currently state that SSRF is generally outside of our threat model, this is something where we should invest to improve this.

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>
---
 lib/private/Http/Client/NegativeDnsCache.php | 51 ++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 lib/private/Http/Client/NegativeDnsCache.php

(limited to 'lib/private/Http/Client/NegativeDnsCache.php')

diff --git a/lib/private/Http/Client/NegativeDnsCache.php b/lib/private/Http/Client/NegativeDnsCache.php
new file mode 100644
index 00000000000..550d75a9c08
--- /dev/null
+++ b/lib/private/Http/Client/NegativeDnsCache.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2021, Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @author Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Http\Client;
+
+use OCP\ICache;
+use OCP\ICacheFactory;
+
+class NegativeDnsCache {
+	/** @var ICache */
+	private $cache;
+
+	public function __construct(ICacheFactory $memcache) {
+		$this->cache = $memcache->createLocal('NegativeDnsCache');
+	}
+
+	private function createCacheKey(string $domain, int $type) : string {
+		return $domain . "-" . (string)$type;
+	}
+
+	public function setNegativeCacheForDnsType(string $domain, int $type, int $ttl) : void {
+		$this->cache->set($this->createCacheKey($domain, $type), "true", $ttl);
+	}
+
+	public function isNegativeCached(string $domain, int $type) : bool {
+		return $this->cache->hasKey($this->createCacheKey($domain, $type));
+	}
+}
-- 
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