fix(ldap): store last known user groups

apps/user_ldap/lib/Connection.php

@@ -298,6 +298,10 @@ public function getFromCache($key) {
 		return json_decode(base64_decode($this->cache->get($key) ?? ''), true);
 	}
 
+	public function getConfigPrefix(): string {
+		return $this->configPrefix;
+	}
+
 	/**
 	 * @param string $key
 	 * @param mixed $value

apps/user_ldap/lib/Group_LDAP.php

@@ -46,12 +46,17 @@
 
 use Exception;
 use OC\ServerNotAvailableException;
+use OCA\User_LDAP\User\OfflineUser;
 use OCP\Cache\CappedMemoryCache;
 use OCP\GroupInterface;
 use OCP\Group\Backend\ABackend;
 use OCP\Group\Backend\IDeleteGroupBackend;
 use OCP\Group\Backend\IGetDisplayNameBackend;
+use OCP\IConfig;
+use OCP\IUserManager;
+use OCP\Server;
 use Psr\Log\LoggerInterface;
+use function json_decode;
 
 class Group_LDAP extends ABackend implements GroupInterface, IGroupLDAP, IGetDisplayNameBackend, IDeleteGroupBackend {
 	protected bool $enabled = false;
@@ -70,8 +75,15 @@ class Group_LDAP extends ABackend implements GroupInterface, IGroupLDAP, IGetDis
 	 * @var string $ldapGroupMemberAssocAttr contains the LDAP setting (in lower case) with the same name
 	 */
 	protected string $ldapGroupMemberAssocAttr;
-
-	public function __construct(Access $access, GroupPluginManager $groupPluginManager) {
+	private IConfig $config;
+	private IUserManager $ncUserManager;
+
+	public function __construct(
+		Access $access,
+		GroupPluginManager $groupPluginManager,
+		IConfig $config,
+		IUserManager $ncUserManager
+	) {
 		$this->access = $access;
 		$filter = $this->access->connection->ldapGroupFilter;
 		$gAssoc = $this->access->connection->ldapGroupMemberAssocAttr;
@@ -83,8 +95,10 @@ public function __construct(Access $access, GroupPluginManager $groupPluginManag
 		$this->cachedGroupsByMember = new CappedMemoryCache();
 		$this->cachedNestedGroups = new CappedMemoryCache();
 		$this->groupPluginManager = $groupPluginManager;
-		$this->logger = \OCP\Server::get(LoggerInterface::class);
+		$this->logger = Server::get(LoggerInterface::class);
 		$this->ldapGroupMemberAssocAttr = strtolower((string)$gAssoc);
+		$this->config = $config;
+		$this->ncUserManager = $ncUserManager;
 	}
 
 	/**
@@ -439,6 +453,7 @@ public function getGroupGidNumber(string $dn) {
 	public function getUserGidNumber(string $dn) {
 		$gidNumber = false;
 		if ($this->access->connection->hasGidNumber) {
+			// FIXME: when $dn does not exist on LDAP anymore, this will be set wrongly to false :/
 			$gidNumber = $this->getEntryGidNumber($dn, $this->access->connection->ldapGidNumber);
 			if ($gidNumber === false) {
 				$this->access->connection->hasGidNumber = false;
@@ -653,6 +668,25 @@ public function getUserPrimaryGroup(string $dn) {
 		return false;
 	}
 
+	private function isUserOnLDAP(string $uid): bool {
+		// forces a user exists check - but does not help if a positive result is cached, while group info is not
+		$ncUser = $this->ncUserManager->get($uid);
+		if ($ncUser === null) {
+			return false;
+		}
+		$backend = $ncUser->getBackend();
+		if ($backend instanceof User_Proxy) {
+			// ignoring cache as safeguard (and we are behind the group cache check anyway)
+			return $backend->userExistsOnLDAP($uid, true);
+		}
+		return false;
+	}
+
+	protected function getCachedGroupsForUserId(string $uid): array {
+		$groupStr = $this->config->getUserValue($uid, 'user_ldap', 'cached-group-memberships-' . $this->access->connection->getConfigPrefix(), '[]');
+		return json_decode($groupStr) ?? [];
+	}
+
 	/**
 	 * This function fetches all groups a user belongs to. It does not check
 	 * if the user exists at all.
@@ -664,15 +698,25 @@ public function getUserPrimaryGroup(string $dn) {
 	 * @throws Exception
 	 * @throws ServerNotAvailableException
 	 */
-	public function getUserGroups($uid) {
+	public function getUserGroups($uid): array {
 		if (!$this->enabled) {
 			return [];
 		}
+		$ncUid = $uid;
+
 		$cacheKey = 'getUserGroups' . $uid;
 		$userGroups = $this->access->connection->getFromCache($cacheKey);
 		if (!is_null($userGroups)) {
 			return $userGroups;
 		}
+
+		$user = $this->access->userManager->get($uid);
+		if ($user instanceof OfflineUser) {
+			// We load known group memberships from configuration for remnants,
+			// because LDAP server does not contain them anymore
+			return $this->getCachedGroupsForUserId($uid);
+		}
+
 		$userDN = $this->access->username2dn($uid);
 		if (!$userDN) {
 			$this->access->connection->writeToCache($cacheKey, []);
@@ -784,9 +828,21 @@ public function getUserGroups($uid) {
 			$groups[] = $gidGroupName;
 		}
 
+		if (empty($groups) && !$this->isUserOnLDAP($ncUid)) {
+			// Groups are enabled, but you user has none? Potentially suspicious:
+			// it could be that the user was deleted from LDAP, but we are not
+			// aware of it yet.
+			$groups = $this->getCachedGroupsForUserId($ncUid);
+			$this->access->connection->writeToCache($cacheKey, $groups);
+			return $groups;
+		}
+
 		$groups = array_unique($groups, SORT_LOCALE_STRING);
 		$this->access->connection->writeToCache($cacheKey, $groups);
 
+		$groupStr = \json_encode($groups);
+		$this->config->setUserValue($ncUid, 'user_ldap', 'cached-group-memberships-' . $this->access->connection->getConfigPrefix(), $groupStr);
+
 		return $groups;
 	}
 

apps/user_ldap/lib/Group_Proxy.php

@@ -35,23 +35,31 @@
 use OCP\Group\Backend\IGroupDetailsBackend;
 use OCP\Group\Backend\INamedBackend;
 use OCP\GroupInterface;
+use OCP\IConfig;
+use OCP\IUserManager;
 
 class Group_Proxy extends Proxy implements \OCP\GroupInterface, IGroupLDAP, IGetDisplayNameBackend, INamedBackend, IDeleteGroupBackend, IBatchMethodsBackend {
 	private $backends = [];
 	private ?Group_LDAP $refBackend = null;
 	private Helper $helper;
 	private GroupPluginManager $groupPluginManager;
 	private bool $isSetUp = false;
+	private IConfig $config;
+	private IUserManager $ncUserManager;
 
 	public function __construct(
 		Helper $helper,
 		ILDAPWrapper $ldap,
 		AccessFactory $accessFactory,
-		GroupPluginManager $groupPluginManager
+		GroupPluginManager $groupPluginManager,
+		IConfig $config,
+		IUserManager $ncUserManager,
 	) {
 		parent::__construct($ldap, $accessFactory);
 		$this->helper = $helper;
 		$this->groupPluginManager = $groupPluginManager;
+		$this->config = $config;
+		$this->ncUserManager = $ncUserManager;
 	}
 
 	protected function setup(): void {
@@ -62,7 +70,7 @@ protected function setup(): void {
 		$serverConfigPrefixes = $this->helper->getServerConfigurationPrefixes(true);
 		foreach ($serverConfigPrefixes as $configPrefix) {
 			$this->backends[$configPrefix] =
-				new Group_LDAP($this->getAccess($configPrefix), $this->groupPluginManager);
+				new Group_LDAP($this->getAccess($configPrefix), $this->groupPluginManager, $this->config, $this->ncUserManager);
 			if (is_null($this->refBackend)) {
 				$this->refBackend = &$this->backends[$configPrefix];
 			}