feat(share): make sharelink token length configurable

Signed-off-by: ernolf <raphael.gradenwitz@googlemail.com>

Author: ernolf

lib/private/Share/Constants.php

@@ -63,7 +63,10 @@ class Constants {
 
 	public const RESPONSE_FORMAT = 'json'; // default response format for ocs calls
 
-	public const TOKEN_LENGTH = 15; // old (oc7) length is 32, keep token length in db at least that for compatibility
+	public const MIN_TOKEN_LENGTH = 4; // 14,776,336 different possible variations
+	public const DEFAULT_TOKEN_LENGTH = 15; // 768,909,704,948,766,668,552,634,368 different possible variations
+	public const MAX_TOKEN_LENGTH = 32; // 2,272,657,884,496,751,345,355,241,563,627,544,170,162,852,933,518,655,225,856 different possible variations
+	public const TOKEN_LENGTH = self::DEFAULT_TOKEN_LENGTH; // old (oc7) length is 32, keep token length in db at least that for compatibility
 
 	protected static $shareTypeUserAndGroups = -1;
 	protected static $shareTypeGroupUserUnique = 2;

lib/private/Share/Helper.php

@@ -126,4 +126,18 @@ public static function isSameUserOnSameServer($user1, $server1, $user2, $server2
 
 		return false;
 	}
+
+	public static function getTokenLength(): int {
+		$config = \OC::$server->getConfig();
+		$tokenLength = (int)$config->getAppValue('core', 'shareapi_token_length', self::DEFAULT_TOKEN_LENGTH);
+
+		// Token length should be within the defined min and max limits
+		if ($tokenLength < self::MIN_TOKEN_LENGTH) {
+			$tokenLength = self::MIN_TOKEN_LENGTH;
+		} elseif ($tokenLength > self::MAX_TOKEN_LENGTH) {
+			$tokenLength = self::MAX_TOKEN_LENGTH;
+		}
+
+		return $tokenLength;
+	}
 }

lib/private/Share20/Manager.php

@@ -667,7 +667,7 @@ public function createShare(IShare $share) {
 				// For now ignore a set token.
 				$share->setToken(
 					$this->secureRandom->generate(
-						\OC\Share\Constants::TOKEN_LENGTH,
+						\OC\Share\Constants\Helper::getTokenLength(),
 						\OCP\Security\ISecureRandom::CHAR_HUMAN_READABLE
 					)
 				);