nextcloud / server

apps/user_ldap/lib/Access.php

Indentation +1938 added lines, -1938 removed lines

@@ -67,1734 +67,1734 @@ 
  * @package OCA\User_LDAP
  */
 class Access extends LDAPUtility {
-	public const UUID_ATTRIBUTES = ['entryuuid', 'nsuniqueid', 'objectguid', 'guid', 'ipauniqueid'];
-
-	/** @var \OCA\User_LDAP\Connection */
-	public $connection;
-	/** @var Manager */
-	public $userManager;
-	/**
-	 * never ever check this var directly, always use getPagedSearchResultState
-	 * @var ?bool
-	 */
-	protected $pagedSearchedSuccessful;
-
-	/** @var ?AbstractMapping */
-	protected $userMapper;
-
-	/** @var ?AbstractMapping */
-	protected $groupMapper;
-
-	/**
-	 * @var \OCA\User_LDAP\Helper
-	 */
-	private $helper;
-	/** @var IConfig */
-	private $config;
-	/** @var IUserManager */
-	private $ncUserManager;
-	/** @var LoggerInterface */
-	private $logger;
-	private string $lastCookie = '';
-
-	public function __construct(
-		Connection $connection,
-		ILDAPWrapper $ldap,
-		Manager $userManager,
-		Helper $helper,
-		IConfig $config,
-		IUserManager $ncUserManager,
-		LoggerInterface $logger
-	) {
-		parent::__construct($ldap);
-		$this->connection = $connection;
-		$this->userManager = $userManager;
-		$this->userManager->setLdapAccess($this);
-		$this->helper = $helper;
-		$this->config = $config;
-		$this->ncUserManager = $ncUserManager;
-		$this->logger = $logger;
-	}
-
-	/**
-	 * sets the User Mapper
-	 */
-	public function setUserMapper(AbstractMapping $mapper): void {
-		$this->userMapper = $mapper;
-	}
-
-	/**
-	 * @throws \Exception
-	 */
-	public function getUserMapper(): AbstractMapping {
-		if (is_null($this->userMapper)) {
-			throw new \Exception('UserMapper was not assigned to this Access instance.');
-		}
-		return $this->userMapper;
-	}
-
-	/**
-	 * sets the Group Mapper
-	 */
-	public function setGroupMapper(AbstractMapping $mapper): void {
-		$this->groupMapper = $mapper;
-	}
-
-	/**
-	 * returns the Group Mapper
-	 *
-	 * @throws \Exception
-	 */
-	public function getGroupMapper(): AbstractMapping {
-		if (is_null($this->groupMapper)) {
-			throw new \Exception('GroupMapper was not assigned to this Access instance.');
-		}
-		return $this->groupMapper;
-	}
-
-	/**
-	 * @return bool
-	 */
-	private function checkConnection() {
-		return ($this->connection instanceof Connection);
-	}
-
-	/**
-	 * returns the Connection instance
-	 *
-	 * @return \OCA\User_LDAP\Connection
-	 */
-	public function getConnection() {
-		return $this->connection;
-	}
-
-	/**
-	 * reads a given attribute for an LDAP record identified by a DN
-	 *
-	 * @param string $dn the record in question
-	 * @param string $attr the attribute that shall be retrieved
-	 *        if empty, just check the record's existence
-	 * @param string $filter
-	 * @return array|false an array of values on success or an empty
-	 *          array if $attr is empty, false otherwise
-	 * @throws ServerNotAvailableException
-	 */
-	public function readAttribute(string $dn, string $attr, string $filter = 'objectClass=*') {
-		if (!$this->checkConnection()) {
-			$this->logger->warning(
-				'No LDAP Connector assigned, access impossible for readAttribute.',
-				['app' => 'user_ldap']
-			);
-			return false;
-		}
-		$cr = $this->connection->getConnectionResource();
-		if (!$this->ldap->isResource($cr)) {
-			//LDAP not available
-			$this->logger->debug('LDAP resource not available.', ['app' => 'user_ldap']);
-			return false;
-		}
-		$attr = mb_strtolower($attr, 'UTF-8');
-		// the actual read attribute later may contain parameters on a ranged
-		// request, e.g. member;range=99-199. Depends on server reply.
-		$attrToRead = $attr;
-
-		$values = [];
-		$isRangeRequest = false;
-		do {
-			$result = $this->executeRead($dn, $attrToRead, $filter);
-			if (is_bool($result)) {
-				// when an exists request was run and it was successful, an empty
-				// array must be returned
-				return $result ? [] : false;
-			}
-
-			if (!$isRangeRequest) {
-				$values = $this->extractAttributeValuesFromResult($result, $attr);
-				if (!empty($values)) {
-					return $values;
-				}
-			}
-
-			$isRangeRequest = false;
-			$result = $this->extractRangeData($result, $attr);
-			if (!empty($result)) {
-				$normalizedResult = $this->extractAttributeValuesFromResult(
-					[$attr => $result['values']],
-					$attr
-				);
-				$values = array_merge($values, $normalizedResult);
-
-				if ($result['rangeHigh'] === '*') {
-					// when server replies with * as high range value, there are
-					// no more results left
-					return $values;
-				} else {
-					$low = $result['rangeHigh'] + 1;
-					$attrToRead = $result['attributeName'] . ';range=' . $low . '-*';
-					$isRangeRequest = true;
-				}
-			}
-		} while ($isRangeRequest);
-
-		$this->logger->debug('Requested attribute ' . $attr . ' not found for ' . $dn, ['app' => 'user_ldap']);
-		return false;
-	}
-
-	/**
-	 * Runs an read operation against LDAP
-	 *
-	 * @return array|bool false if there was any error, true if an exists check
-	 *                    was performed and the requested DN found, array with the
-	 *                    returned data on a successful usual operation
-	 * @throws ServerNotAvailableException
-	 */
-	public function executeRead(string $dn, string $attribute, string $filter) {
-		$dn = $this->helper->DNasBaseParameter($dn);
-		$rr = @$this->invokeLDAPMethod('read', $dn, $filter, [$attribute]);
-		if (!$this->ldap->isResource($rr)) {
-			if ($attribute !== '') {
-				//do not throw this message on userExists check, irritates
-				$this->logger->debug('readAttribute failed for DN ' . $dn, ['app' => 'user_ldap']);
-			}
-			//in case an error occurs , e.g. object does not exist
-			return false;
-		}
-		if ($attribute === '' && ($filter === 'objectclass=*' || $this->invokeLDAPMethod('countEntries', $rr) === 1)) {
-			$this->logger->debug('readAttribute: ' . $dn . ' found', ['app' => 'user_ldap']);
-			return true;
-		}
-		$er = $this->invokeLDAPMethod('firstEntry', $rr);
-		if (!$this->ldap->isResource($er)) {
-			//did not match the filter, return false
-			return false;
-		}
-		//LDAP attributes are not case sensitive
-		$result = \OCP\Util::mb_array_change_key_case(
-			$this->invokeLDAPMethod('getAttributes', $er), MB_CASE_LOWER, 'UTF-8');
-
-		return $result;
-	}
-
-	/**
-	 * Normalizes a result grom getAttributes(), i.e. handles DNs and binary
-	 * data if present.
-	 *
-	 * @param array $result from ILDAPWrapper::getAttributes()
-	 * @param string $attribute the attribute name that was read
-	 * @return string[]
-	 */
-	public function extractAttributeValuesFromResult($result, $attribute) {
-		$values = [];
-		if (isset($result[$attribute]) && $result[$attribute]['count'] > 0) {
-			$lowercaseAttribute = strtolower($attribute);
-			for ($i = 0; $i < $result[$attribute]['count']; $i++) {
-				if ($this->resemblesDN($attribute)) {
-					$values[] = $this->helper->sanitizeDN($result[$attribute][$i]);
-				} elseif ($lowercaseAttribute === 'objectguid' || $lowercaseAttribute === 'guid') {
-					$values[] = $this->convertObjectGUID2Str($result[$attribute][$i]);
-				} else {
-					$values[] = $result[$attribute][$i];
-				}
-			}
-		}
-		return $values;
-	}
-
-	/**
-	 * Attempts to find ranged data in a getAttribute results and extracts the
-	 * returned values as well as information on the range and full attribute
-	 * name for further processing.
-	 *
-	 * @param array $result from ILDAPWrapper::getAttributes()
-	 * @param string $attribute the attribute name that was read. Without ";range=…"
-	 * @return array If a range was detected with keys 'values', 'attributeName',
-	 *               'attributeFull' and 'rangeHigh', otherwise empty.
-	 */
-	public function extractRangeData($result, $attribute) {
-		$keys = array_keys($result);
-		foreach ($keys as $key) {
-			if ($key !== $attribute && strpos((string)$key, $attribute) === 0) {
-				$queryData = explode(';', (string)$key);
-				if (strpos($queryData[1], 'range=') === 0) {
-					$high = substr($queryData[1], 1 + strpos($queryData[1], '-'));
-					$data = [
-						'values' => $result[$key],
-						'attributeName' => $queryData[0],
-						'attributeFull' => $key,
-						'rangeHigh' => $high,
-					];
-					return $data;
-				}
-			}
-		}
-		return [];
-	}
-
-	/**
-	 * Set password for an LDAP user identified by a DN
-	 *
-	 * @param string $userDN the user in question
-	 * @param string $password the new password
-	 * @return bool
-	 * @throws HintException
-	 * @throws \Exception
-	 */
-	public function setPassword($userDN, $password) {
-		if ((int)$this->connection->turnOnPasswordChange !== 1) {
-			throw new \Exception('LDAP password changes are disabled.');
-		}
-		$cr = $this->connection->getConnectionResource();
-		if (!$this->ldap->isResource($cr)) {
-			//LDAP not available
-			$this->logger->debug('LDAP resource not available.', ['app' => 'user_ldap']);
-			return false;
-		}
-		try {
-			// try PASSWD extended operation first
-			return @$this->invokeLDAPMethod('exopPasswd', $userDN, '', $password) ||
-				@$this->invokeLDAPMethod('modReplace', $userDN, $password);
-		} catch (ConstraintViolationException $e) {
-			throw new HintException('Password change rejected.', \OC::$server->getL10N('user_ldap')->t('Password change rejected. Hint: ') . $e->getMessage(), (int)$e->getCode());
-		}
-	}
-
-	/**
-	 * checks whether the given attributes value is probably a DN
-	 *
-	 * @param string $attr the attribute in question
-	 * @return boolean if so true, otherwise false
-	 */
-	private function resemblesDN($attr) {
-		$resemblingAttributes = [
-			'dn',
-			'uniquemember',
-			'member',
-			// memberOf is an "operational" attribute, without a definition in any RFC
-			'memberof'
-		];
-		return in_array($attr, $resemblingAttributes);
-	}
-
-	/**
-	 * checks whether the given string is probably a DN
-	 *
-	 * @param string $string
-	 * @return boolean
-	 */
-	public function stringResemblesDN($string) {
-		$r = $this->ldap->explodeDN($string, 0);
-		// if exploding a DN succeeds and does not end up in
-		// an empty array except for $r[count] being 0.
-		return (is_array($r) && count($r) > 1);
-	}
-
-	/**
-	 * returns a DN-string that is cleaned from not domain parts, e.g.
-	 * cn=foo,cn=bar,dc=foobar,dc=server,dc=org
-	 * becomes dc=foobar,dc=server,dc=org
-	 *
-	 * @param string $dn
-	 * @return string
-	 */
-	public function getDomainDNFromDN($dn) {
-		$allParts = $this->ldap->explodeDN($dn, 0);
-		if ($allParts === false) {
-			//not a valid DN
-			return '';
-		}
-		$domainParts = [];
-		$dcFound = false;
-		foreach ($allParts as $part) {
-			if (!$dcFound && strpos($part, 'dc=') === 0) {
-				$dcFound = true;
-			}
-			if ($dcFound) {
-				$domainParts[] = $part;
-			}
-		}
-		return implode(',', $domainParts);
-	}
-
-	/**
-	 * returns the LDAP DN for the given internal Nextcloud name of the group
-	 *
-	 * @param string $name the Nextcloud name in question
-	 * @return string|false LDAP DN on success, otherwise false
-	 */
-	public function groupname2dn($name) {
-		return $this->getGroupMapper()->getDNByName($name);
-	}
-
-	/**
-	 * returns the LDAP DN for the given internal Nextcloud name of the user
-	 *
-	 * @param string $name the Nextcloud name in question
-	 * @return string|false with the LDAP DN on success, otherwise false
-	 */
-	public function username2dn($name) {
-		$fdn = $this->getUserMapper()->getDNByName($name);
-
-		//Check whether the DN belongs to the Base, to avoid issues on multi-
-		//server setups
-		if (is_string($fdn) && $this->isDNPartOfBase($fdn, $this->connection->ldapBaseUsers)) {
-			return $fdn;
-		}
-
-		return false;
-	}
-
-	/**
-	 * returns the internal Nextcloud name for the given LDAP DN of the group, false on DN outside of search DN or failure
-	 *
-	 * @param string $fdn the dn of the group object
-	 * @param string $ldapName optional, the display name of the object
-	 * @return string|false with the name to use in Nextcloud, false on DN outside of search DN
-	 * @throws \Exception
-	 */
-	public function dn2groupname($fdn, $ldapName = null) {
-		//To avoid bypassing the base DN settings under certain circumstances
-		//with the group support, check whether the provided DN matches one of
-		//the given Bases
-		if (!$this->isDNPartOfBase($fdn, $this->connection->ldapBaseGroups)) {
-			return false;
-		}
-
-		return $this->dn2ocname($fdn, $ldapName, false);
-	}
-
-	/**
-	 * returns the internal Nextcloud name for the given LDAP DN of the user, false on DN outside of search DN or failure
-	 *
-	 * @param string $fdn the dn of the user object
-	 * @param string $ldapName optional, the display name of the object
-	 * @return string|false with with the name to use in Nextcloud
-	 * @throws \Exception
-	 */
-	public function dn2username($fdn, $ldapName = null) {
-		//To avoid bypassing the base DN settings under certain circumstances
-		//with the group support, check whether the provided DN matches one of
-		//the given Bases
-		if (!$this->isDNPartOfBase($fdn, $this->connection->ldapBaseUsers)) {
-			return false;
-		}
-
-		return $this->dn2ocname($fdn, $ldapName, true);
-	}
-
-	/**
-	 * returns an internal Nextcloud name for the given LDAP DN, false on DN outside of search DN
-	 *
-	 * @param string $fdn the dn of the user object
-	 * @param string|null $ldapName optional, the display name of the object
-	 * @param bool $isUser optional, whether it is a user object (otherwise group assumed)
-	 * @param bool|null $newlyMapped
-	 * @param array|null $record
-	 * @return false|string with with the name to use in Nextcloud
-	 * @throws \Exception
-	 */
-	public function dn2ocname($fdn, $ldapName = null, $isUser = true, &$newlyMapped = null, array $record = null) {
-		static $intermediates = [];
-		if (isset($intermediates[($isUser ? 'user-' : 'group-') . $fdn])) {
-			return false; // is a known intermediate
-		}
-
-		$newlyMapped = false;
-		if ($isUser) {
-			$mapper = $this->getUserMapper();
-			$nameAttribute = $this->connection->ldapUserDisplayName;
-			$filter = $this->connection->ldapUserFilter;
-		} else {
-			$mapper = $this->getGroupMapper();
-			$nameAttribute = $this->connection->ldapGroupDisplayName;
-			$filter = $this->connection->ldapGroupFilter;
-		}
-
-		//let's try to retrieve the Nextcloud name from the mappings table
-		$ncName = $mapper->getNameByDN($fdn);
-		if (is_string($ncName)) {
-			return $ncName;
-		}
-
-		//second try: get the UUID and check if it is known. Then, update the DN and return the name.
-		$uuid = $this->getUUID($fdn, $isUser, $record);
-		if (is_string($uuid)) {
-			$ncName = $mapper->getNameByUUID($uuid);
-			if (is_string($ncName)) {
-				$mapper->setDNbyUUID($fdn, $uuid);
-				return $ncName;
-			}
-		} else {
-			//If the UUID can't be detected something is foul.
-			$this->logger->debug('Cannot determine UUID for ' . $fdn . '. Skipping.', ['app' => 'user_ldap']);
-			return false;
-		}
-
-		if (is_null($ldapName)) {
-			$ldapName = $this->readAttribute($fdn, $nameAttribute, $filter);
-			if (!isset($ldapName[0]) || empty($ldapName[0])) {
-				$this->logger->debug('No or empty name for ' . $fdn . ' with filter ' . $filter . '.', ['app' => 'user_ldap']);
-				$intermediates[($isUser ? 'user-' : 'group-') . $fdn] = true;
-				return false;
-			}
-			$ldapName = $ldapName[0];
-		}
-
-		if ($isUser) {
-			$usernameAttribute = (string)$this->connection->ldapExpertUsernameAttr;
-			if ($usernameAttribute !== '') {
-				$username = $this->readAttribute($fdn, $usernameAttribute);
-				if (!isset($username[0]) || empty($username[0])) {
-					$this->logger->debug('No or empty username (' . $usernameAttribute . ') for ' . $fdn . '.', ['app' => 'user_ldap']);
-					return false;
-				}
-				$username = $username[0];
-			} else {
-				$username = $uuid;
-			}
-			try {
-				$intName = $this->sanitizeUsername($username);
-			} catch (\InvalidArgumentException $e) {
-				$this->logger->warning('Error sanitizing username: ' . $e->getMessage(), [
-					'exception' => $e,
-				]);
-				// we don't attempt to set a username here. We can go for
-				// for an alternative 4 digit random number as we would append
-				// otherwise, however it's likely not enough space in bigger
-				// setups, and most importantly: this is not intended.
-				return false;
-			}
-		} else {
-			$intName = $this->sanitizeGroupIDCandidate($ldapName);
-		}
-
-		//a new user/group! Add it only if it doesn't conflict with other backend's users or existing groups
-		//disabling Cache is required to avoid that the new user is cached as not-existing in fooExists check
-		//NOTE: mind, disabling cache affects only this instance! Using it
-		// outside of core user management will still cache the user as non-existing.
-		$originalTTL = $this->connection->ldapCacheTTL;
-		$this->connection->setConfiguration(['ldapCacheTTL' => 0]);
-		if ($intName !== ''
-			&& (($isUser && !$this->ncUserManager->userExists($intName))
-				|| (!$isUser && !\OC::$server->getGroupManager()->groupExists($intName))
-			)
-		) {
-			$this->connection->setConfiguration(['ldapCacheTTL' => $originalTTL]);
-			$newlyMapped = $this->mapAndAnnounceIfApplicable($mapper, $fdn, $intName, $uuid, $isUser);
-			if ($newlyMapped) {
-				return $intName;
-			}
-		}
-
-		$this->connection->setConfiguration(['ldapCacheTTL' => $originalTTL]);
-		$altName = $this->createAltInternalOwnCloudName($intName, $isUser);
-		if (is_string($altName)) {
-			if ($this->mapAndAnnounceIfApplicable($mapper, $fdn, $altName, $uuid, $isUser)) {
-				$this->logger->warning(
-					'Mapped {fdn} as {altName} because of a name collision on {intName}.',
-					[
-						'fdn' => $fdn,
-						'altName' => $altName,
-						'intName' => $intName,
-						'app' => 'user_ldap',
-					]
-				);
-				$newlyMapped = true;
-				return $altName;
-			}
-		}
-
-		//if everything else did not help..
-		$this->logger->info('Could not create unique name for ' . $fdn . '.', ['app' => 'user_ldap']);
-		return false;
-	}
-
-	public function mapAndAnnounceIfApplicable(
-		AbstractMapping $mapper,
-		string $fdn,
-		string $name,
-		string $uuid,
-		bool $isUser
-	): bool {
-		if ($mapper->map($fdn, $name, $uuid)) {
-			if ($this->ncUserManager instanceof PublicEmitter && $isUser) {
-				$this->cacheUserExists($name);
-				$this->ncUserManager->emit('\OC\User', 'assignedUserId', [$name]);
-			} elseif (!$isUser) {
-				$this->cacheGroupExists($name);
-			}
-			return true;
-		}
-		return false;
-	}
-
-	/**
-	 * gives back the user names as they are used ownClod internally
-	 *
-	 * @param array $ldapUsers as returned by fetchList()
-	 * @return array an array with the user names to use in Nextcloud
-	 *
-	 * gives back the user names as they are used ownClod internally
-	 * @throws \Exception
-	 */
-	public function nextcloudUserNames($ldapUsers) {
-		return $this->ldap2NextcloudNames($ldapUsers, true);
-	}
-
-	/**
-	 * gives back the group names as they are used ownClod internally
-	 *
-	 * @param array $ldapGroups as returned by fetchList()
-	 * @return array an array with the group names to use in Nextcloud
-	 *
-	 * gives back the group names as they are used ownClod internally
-	 * @throws \Exception
-	 */
-	public function nextcloudGroupNames($ldapGroups) {
-		return $this->ldap2NextcloudNames($ldapGroups, false);
-	}
-
-	/**
-	 * @param array[] $ldapObjects as returned by fetchList()
-	 * @throws \Exception
-	 */
-	private function ldap2NextcloudNames(array $ldapObjects, bool $isUsers): array {
-		if ($isUsers) {
-			$nameAttribute = $this->connection->ldapUserDisplayName;
-			$sndAttribute = $this->connection->ldapUserDisplayName2;
-		} else {
-			$nameAttribute = $this->connection->ldapGroupDisplayName;
-			$sndAttribute = null;
-		}
-		$nextcloudNames = [];
-
-		foreach ($ldapObjects as $ldapObject) {
-			$nameByLDAP = $ldapObject[$nameAttribute][0] ?? null;
-
-			$ncName = $this->dn2ocname($ldapObject['dn'][0], $nameByLDAP, $isUsers);
-			if ($ncName) {
-				$nextcloudNames[] = $ncName;
-				if ($isUsers) {
-					$this->updateUserState($ncName);
-					//cache the user names so it does not need to be retrieved
-					//again later (e.g. sharing dialogue).
-					if (is_null($nameByLDAP)) {
-						continue;
-					}
-					$sndName = $ldapObject[$sndAttribute][0] ?? '';
-					$this->cacheUserDisplayName($ncName, $nameByLDAP, $sndName);
-				} elseif ($nameByLDAP !== null) {
-					$this->cacheGroupDisplayName($ncName, $nameByLDAP);
-				}
-			}
-		}
-		return $nextcloudNames;
-	}
-
-	/**
-	 * removes the deleted-flag of a user if it was set
-	 *
-	 * @param string $ncname
-	 * @throws \Exception
-	 */
-	public function updateUserState($ncname): void {
-		$user = $this->userManager->get($ncname);
-		if ($user instanceof OfflineUser) {
-			$user->unmark();
-		}
-	}
-
-	/**
-	 * caches the user display name
-	 *
-	 * @param string $ocName the internal Nextcloud username
-	 * @param string|false $home the home directory path
-	 */
-	public function cacheUserHome(string $ocName, $home): void {
-		$cacheKey = 'getHome' . $ocName;
-		$this->connection->writeToCache($cacheKey, $home);
-	}
-
-	/**
-	 * caches a user as existing
-	 */
-	public function cacheUserExists(string $ocName): void {
-		$this->connection->writeToCache('userExists' . $ocName, true);
-	}
-
-	/**
-	 * caches a group as existing
-	 */
-	public function cacheGroupExists(string $gid): void {
-		$this->connection->writeToCache('groupExists' . $gid, true);
-	}
-
-	/**
-	 * caches the user display name
-	 *
-	 * @param string $ocName the internal Nextcloud username
-	 * @param string $displayName the display name
-	 * @param string $displayName2 the second display name
-	 * @throws \Exception
-	 */
-	public function cacheUserDisplayName(string $ocName, string $displayName, string $displayName2 = ''): void {
-		$user = $this->userManager->get($ocName);
-		if ($user === null) {
-			return;
-		}
-		$displayName = $user->composeAndStoreDisplayName($displayName, $displayName2);
-		$cacheKeyTrunk = 'getDisplayName';
-		$this->connection->writeToCache($cacheKeyTrunk . $ocName, $displayName);
-	}
-
-	public function cacheGroupDisplayName(string $ncName, string $displayName): void {
-		$cacheKey = 'group_getDisplayName' . $ncName;
-		$this->connection->writeToCache($cacheKey, $displayName);
-	}
-
-	/**
-	 * creates a unique name for internal Nextcloud use for users. Don't call it directly.
-	 *
-	 * @param string $name the display name of the object
-	 * @return string|false with with the name to use in Nextcloud or false if unsuccessful
-	 *
-	 * Instead of using this method directly, call
-	 * createAltInternalOwnCloudName($name, true)
-	 */
-	private function _createAltInternalOwnCloudNameForUsers(string $name) {
-		$attempts = 0;
-		//while loop is just a precaution. If a name is not generated within
-		//20 attempts, something else is very wrong. Avoids infinite loop.
-		while ($attempts < 20) {
-			$altName = $name . '_' . rand(1000, 9999);
-			if (!$this->ncUserManager->userExists($altName)) {
-				return $altName;
-			}
-			$attempts++;
-		}
-		return false;
-	}
-
-	/**
-	 * creates a unique name for internal Nextcloud use for groups. Don't call it directly.
-	 *
-	 * @param string $name the display name of the object
-	 * @return string|false with with the name to use in Nextcloud or false if unsuccessful.
-	 *
-	 * Instead of using this method directly, call
-	 * createAltInternalOwnCloudName($name, false)
-	 *
-	 * Group names are also used as display names, so we do a sequential
-	 * numbering, e.g. Developers_42 when there are 41 other groups called
-	 * "Developers"
-	 */
-	private function _createAltInternalOwnCloudNameForGroups(string $name) {
-		$usedNames = $this->getGroupMapper()->getNamesBySearch($name, "", '_%');
-		if (count($usedNames) === 0) {
-			$lastNo = 1; //will become name_2
-		} else {
-			natsort($usedNames);
-			$lastName = array_pop($usedNames);
-			$lastNo = (int)substr($lastName, strrpos($lastName, '_') + 1);
-		}
-		$altName = $name . '_' . (string)($lastNo + 1);
-		unset($usedNames);
-
-		$attempts = 1;
-		while ($attempts < 21) {
-			// Check to be really sure it is unique
-			// while loop is just a precaution. If a name is not generated within
-			// 20 attempts, something else is very wrong. Avoids infinite loop.
-			if (!\OC::$server->getGroupManager()->groupExists($altName)) {
-				return $altName;
-			}
-			$altName = $name . '_' . ($lastNo + $attempts);
-			$attempts++;
-		}
-		return false;
-	}
-
-	/**
-	 * creates a unique name for internal Nextcloud use.
-	 *
-	 * @param string $name the display name of the object
-	 * @param bool $isUser whether name should be created for a user (true) or a group (false)
-	 * @return string|false with with the name to use in Nextcloud or false if unsuccessful
-	 */
-	private function createAltInternalOwnCloudName(string $name, bool $isUser) {
-		// ensure there is space for the "_1234" suffix
-		if (strlen($name) > 59) {
-			$name = substr($name, 0, 59);
-		}
-
-		$originalTTL = $this->connection->ldapCacheTTL;
-		$this->connection->setConfiguration(['ldapCacheTTL' => 0]);
-		if ($isUser) {
-			$altName = $this->_createAltInternalOwnCloudNameForUsers($name);
-		} else {
-			$altName = $this->_createAltInternalOwnCloudNameForGroups($name);
-		}
-		$this->connection->setConfiguration(['ldapCacheTTL' => $originalTTL]);
-
-		return $altName;
-	}
-
-	/**
-	 * fetches a list of users according to a provided loginName and utilizing
-	 * the login filter.
-	 */
-	public function fetchUsersByLoginName(string $loginName, array $attributes = ['dn']): array {
-		$loginName = $this->escapeFilterPart($loginName);
-		$filter = str_replace('%uid', $loginName, $this->connection->ldapLoginFilter);
-		return $this->fetchListOfUsers($filter, $attributes);
-	}
-
-	/**
-	 * counts the number of users according to a provided loginName and
-	 * utilizing the login filter.
-	 *
-	 * @param string $loginName
-	 * @return false|int
-	 */
-	public function countUsersByLoginName($loginName) {
-		$loginName = $this->escapeFilterPart($loginName);
-		$filter = str_replace('%uid', $loginName, $this->connection->ldapLoginFilter);
-		return $this->countUsers($filter);
-	}
-
-	/**
-	 * @throws \Exception
-	 */
-	public function fetchListOfUsers(string $filter, array $attr, int $limit = null, int $offset = null, bool $forceApplyAttributes = false): array {
-		$ldapRecords = $this->searchUsers($filter, $attr, $limit, $offset);
-		$recordsToUpdate = $ldapRecords;
-		if (!$forceApplyAttributes) {
-			$isBackgroundJobModeAjax = $this->config
-					->getAppValue('core', 'backgroundjobs_mode', 'ajax') === 'ajax';
-			$listOfDNs = array_reduce($ldapRecords, function ($listOfDNs, $entry) {
-				$listOfDNs[] = $entry['dn'][0];
-				return $listOfDNs;
-			}, []);
-			$idsByDn = $this->getUserMapper()->getListOfIdsByDn($listOfDNs);
-			$recordsToUpdate = array_filter($ldapRecords, function ($record) use ($isBackgroundJobModeAjax, $idsByDn) {
-				$newlyMapped = false;
-				$uid = $idsByDn[$record['dn'][0]] ?? null;
-				if ($uid === null) {
-					$uid = $this->dn2ocname($record['dn'][0], null, true, $newlyMapped, $record);
-				}
-				if (is_string($uid)) {
-					$this->cacheUserExists($uid);
-				}
-				return ($uid !== false) && ($newlyMapped || $isBackgroundJobModeAjax);
-			});
-		}
-		$this->batchApplyUserAttributes($recordsToUpdate);
-		return $this->fetchList($ldapRecords, $this->manyAttributes($attr));
-	}
-
-	/**
-	 * provided with an array of LDAP user records the method will fetch the
-	 * user object and requests it to process the freshly fetched attributes and
-	 * and their values
-	 *
-	 * @throws \Exception
-	 */
-	public function batchApplyUserAttributes(array $ldapRecords): void {
-		$displayNameAttribute = strtolower((string)$this->connection->ldapUserDisplayName);
-		foreach ($ldapRecords as $userRecord) {
-			if (!isset($userRecord[$displayNameAttribute])) {
-				// displayName is obligatory
-				continue;
-			}
-			$ocName = $this->dn2ocname($userRecord['dn'][0], null, true);
-			if ($ocName === false) {
-				continue;
-			}
-			$this->updateUserState($ocName);
-			$user = $this->userManager->get($ocName);
-			if ($user !== null) {
-				$user->processAttributes($userRecord);
-			} else {
-				$this->logger->debug(
-					"The ldap user manager returned null for $ocName",
-					['app' => 'user_ldap']
-				);
-			}
-		}
-	}
-
-	/**
-	 * @return array[]
-	 */
-	public function fetchListOfGroups(string $filter, array $attr, int $limit = null, int $offset = null): array {
-		$cacheKey = 'fetchListOfGroups_' . $filter . '_' . implode('-', $attr) . '_' . (string)$limit . '_' . (string)$offset;
-		$listOfGroups = $this->connection->getFromCache($cacheKey);
-		if (!is_null($listOfGroups)) {
-			return $listOfGroups;
-		}
-		$groupRecords = $this->searchGroups($filter, $attr, $limit, $offset);
-
-		$listOfDNs = array_reduce($groupRecords, function ($listOfDNs, $entry) {
-			$listOfDNs[] = $entry['dn'][0];
-			return $listOfDNs;
-		}, []);
-		$idsByDn = $this->getGroupMapper()->getListOfIdsByDn($listOfDNs);
-
-		array_walk($groupRecords, function (array $record) use ($idsByDn) {
-			$newlyMapped = false;
-			$gid = $idsByDn[$record['dn'][0]] ?? null;
-			if ($gid === null) {
-				$gid = $this->dn2ocname($record['dn'][0], null, false, $newlyMapped, $record);
-			}
-			if (!$newlyMapped && is_string($gid)) {
-				$this->cacheGroupExists($gid);
-			}
-		});
-		$listOfGroups = $this->fetchList($groupRecords, $this->manyAttributes($attr));
-		$this->connection->writeToCache($cacheKey, $listOfGroups);
-		return $listOfGroups;
-	}
-
-	private function fetchList(array $list, bool $manyAttributes): array {
-		if ($manyAttributes) {
-			return $list;
-		} else {
-			$list = array_reduce($list, function ($carry, $item) {
-				$attribute = array_keys($item)[0];
-				$carry[] = $item[$attribute][0];
-				return $carry;
-			}, []);
-			return array_unique($list, SORT_LOCALE_STRING);
-		}
-	}
-
-	/**
-	 * @throws ServerNotAvailableException
-	 */
-	public function searchUsers(string $filter, array $attr = null, int $limit = null, int $offset = null): array {
-		$result = [];
-		foreach ($this->connection->ldapBaseUsers as $base) {
-			$result = array_merge($result, $this->search($filter, $base, $attr, $limit, $offset));
-		}
-		return $result;
-	}
-
-	/**
-	 * @param string[] $attr
-	 * @return false|int
-	 * @throws ServerNotAvailableException
-	 */
-	public function countUsers(string $filter, array $attr = ['dn'], int $limit = null, int $offset = null) {
-		$result = false;
-		foreach ($this->connection->ldapBaseUsers as $base) {
-			$count = $this->count($filter, [$base], $attr, $limit ?? 0, $offset ?? 0);
-			$result = is_int($count) ? (int)$result + $count : $result;
-		}
-		return $result;
-	}
-
-	/**
-	 * executes an LDAP search, optimized for Groups
-	 *
-	 * @param ?string[] $attr optional, when certain attributes shall be filtered out
-	 *
-	 * Executes an LDAP search
-	 * @throws ServerNotAvailableException
-	 */
-	public function searchGroups(string $filter, array $attr = null, int $limit = null, int $offset = null): array {
-		$result = [];
-		foreach ($this->connection->ldapBaseGroups as $base) {
-			$result = array_merge($result, $this->search($filter, $base, $attr, $limit, $offset));
-		}
-		return $result;
-	}
-
-	/**
-	 * returns the number of available groups
-	 *
-	 * @return int|bool
-	 * @throws ServerNotAvailableException
-	 */
-	public function countGroups(string $filter, array $attr = ['dn'], int $limit = null, int $offset = null) {
-		$result = false;
-		foreach ($this->connection->ldapBaseGroups as $base) {
-			$count = $this->count($filter, [$base], $attr, $limit ?? 0, $offset ?? 0);
-			$result = is_int($count) ? (int)$result + $count : $result;
-		}
-		return $result;
-	}
-
-	/**
-	 * returns the number of available objects on the base DN
-	 *
-	 * @return int|bool
-	 * @throws ServerNotAvailableException
-	 */
-	public function countObjects(int $limit = null, int $offset = null) {
-		$result = false;
-		foreach ($this->connection->ldapBase as $base) {
-			$count = $this->count('objectclass=*', [$base], ['dn'], $limit ?? 0, $offset ?? 0);
-			$result = is_int($count) ? (int)$result + $count : $result;
-		}
-		return $result;
-	}
-
-	/**
-	 * Returns the LDAP handler
-	 *
-	 * @throws \OC\ServerNotAvailableException
-	 */
-
-	/**
-	 * @param mixed[] $arguments
-	 * @return mixed
-	 * @throws \OC\ServerNotAvailableException
-	 */
-	private function invokeLDAPMethod(string $command, ...$arguments) {
-		if ($command == 'controlPagedResultResponse') {
-			// php no longer supports call-time pass-by-reference
-			// thus cannot support controlPagedResultResponse as the third argument
-			// is a reference
-			throw new \InvalidArgumentException('Invoker does not support controlPagedResultResponse, call LDAP Wrapper directly instead.');
-		}
-		if (!method_exists($this->ldap, $command)) {
-			return null;
-		}
-		array_unshift($arguments, $this->connection->getConnectionResource());
-		$doMethod = function () use ($command, &$arguments) {
-			return call_user_func_array([$this->ldap, $command], $arguments);
-		};
-		try {
-			$ret = $doMethod();
-		} catch (ServerNotAvailableException $e) {
-			/* Server connection lost, attempt to reestablish it
+    public const UUID_ATTRIBUTES = ['entryuuid', 'nsuniqueid', 'objectguid', 'guid', 'ipauniqueid'];
+
+    /** @var \OCA\User_LDAP\Connection */
+    public $connection;
+    /** @var Manager */
+    public $userManager;
+    /**
+     * never ever check this var directly, always use getPagedSearchResultState
+     * @var ?bool
+     */
+    protected $pagedSearchedSuccessful;
+
+    /** @var ?AbstractMapping */
+    protected $userMapper;
+
+    /** @var ?AbstractMapping */
+    protected $groupMapper;
+
+    /**
+     * @var \OCA\User_LDAP\Helper
+     */
+    private $helper;
+    /** @var IConfig */
+    private $config;
+    /** @var IUserManager */
+    private $ncUserManager;
+    /** @var LoggerInterface */
+    private $logger;
+    private string $lastCookie = '';
+
+    public function __construct(
+        Connection $connection,
+        ILDAPWrapper $ldap,
+        Manager $userManager,
+        Helper $helper,
+        IConfig $config,
+        IUserManager $ncUserManager,
+        LoggerInterface $logger
+    ) {
+        parent::__construct($ldap);
+        $this->connection = $connection;
+        $this->userManager = $userManager;
+        $this->userManager->setLdapAccess($this);
+        $this->helper = $helper;
+        $this->config = $config;
+        $this->ncUserManager = $ncUserManager;
+        $this->logger = $logger;
+    }
+
+    /**
+     * sets the User Mapper
+     */
+    public function setUserMapper(AbstractMapping $mapper): void {
+        $this->userMapper = $mapper;
+    }
+
+    /**
+     * @throws \Exception
+     */
+    public function getUserMapper(): AbstractMapping {
+        if (is_null($this->userMapper)) {
+            throw new \Exception('UserMapper was not assigned to this Access instance.');
+        }
+        return $this->userMapper;
+    }
+
+    /**
+     * sets the Group Mapper
+     */
+    public function setGroupMapper(AbstractMapping $mapper): void {
+        $this->groupMapper = $mapper;
+    }
+
+    /**
+     * returns the Group Mapper
+     *
+     * @throws \Exception
+     */
+    public function getGroupMapper(): AbstractMapping {
+        if (is_null($this->groupMapper)) {
+            throw new \Exception('GroupMapper was not assigned to this Access instance.');
+        }
+        return $this->groupMapper;
+    }
+
+    /**
+     * @return bool
+     */
+    private function checkConnection() {
+        return ($this->connection instanceof Connection);
+    }
+
+    /**
+     * returns the Connection instance
+     *
+     * @return \OCA\User_LDAP\Connection
+     */
+    public function getConnection() {
+        return $this->connection;
+    }
+
+    /**
+     * reads a given attribute for an LDAP record identified by a DN
+     *
+     * @param string $dn the record in question
+     * @param string $attr the attribute that shall be retrieved
+     *        if empty, just check the record's existence
+     * @param string $filter
+     * @return array|false an array of values on success or an empty
+     *          array if $attr is empty, false otherwise
+     * @throws ServerNotAvailableException
+     */
+    public function readAttribute(string $dn, string $attr, string $filter = 'objectClass=*') {
+        if (!$this->checkConnection()) {
+            $this->logger->warning(
+                'No LDAP Connector assigned, access impossible for readAttribute.',
+                ['app' => 'user_ldap']
+            );
+            return false;
+        }
+        $cr = $this->connection->getConnectionResource();
+        if (!$this->ldap->isResource($cr)) {
+            //LDAP not available
+            $this->logger->debug('LDAP resource not available.', ['app' => 'user_ldap']);
+            return false;
+        }
+        $attr = mb_strtolower($attr, 'UTF-8');
+        // the actual read attribute later may contain parameters on a ranged
+        // request, e.g. member;range=99-199. Depends on server reply.
+        $attrToRead = $attr;
+
+        $values = [];
+        $isRangeRequest = false;
+        do {
+            $result = $this->executeRead($dn, $attrToRead, $filter);
+            if (is_bool($result)) {
+                // when an exists request was run and it was successful, an empty
+                // array must be returned
+                return $result ? [] : false;
+            }
+
+            if (!$isRangeRequest) {
+                $values = $this->extractAttributeValuesFromResult($result, $attr);
+                if (!empty($values)) {
+                    return $values;
+                }
+            }
+
+            $isRangeRequest = false;
+            $result = $this->extractRangeData($result, $attr);
+            if (!empty($result)) {
+                $normalizedResult = $this->extractAttributeValuesFromResult(
+                    [$attr => $result['values']],
+                    $attr
+                );
+                $values = array_merge($values, $normalizedResult);
+
+                if ($result['rangeHigh'] === '*') {
+                    // when server replies with * as high range value, there are
+                    // no more results left
+                    return $values;
+                } else {
+                    $low = $result['rangeHigh'] + 1;
+                    $attrToRead = $result['attributeName'] . ';range=' . $low . '-*';
+                    $isRangeRequest = true;
+                }
+            }
+        } while ($isRangeRequest);
+
+        $this->logger->debug('Requested attribute ' . $attr . ' not found for ' . $dn, ['app' => 'user_ldap']);
+        return false;
+    }
+
+    /**
+     * Runs an read operation against LDAP
+     *
+     * @return array|bool false if there was any error, true if an exists check
+     *                    was performed and the requested DN found, array with the
+     *                    returned data on a successful usual operation
+     * @throws ServerNotAvailableException
+     */
+    public function executeRead(string $dn, string $attribute, string $filter) {
+        $dn = $this->helper->DNasBaseParameter($dn);
+        $rr = @$this->invokeLDAPMethod('read', $dn, $filter, [$attribute]);
+        if (!$this->ldap->isResource($rr)) {
+            if ($attribute !== '') {
+                //do not throw this message on userExists check, irritates
+                $this->logger->debug('readAttribute failed for DN ' . $dn, ['app' => 'user_ldap']);
+            }
+            //in case an error occurs , e.g. object does not exist
+            return false;
+        }
+        if ($attribute === '' && ($filter === 'objectclass=*' || $this->invokeLDAPMethod('countEntries', $rr) === 1)) {
+            $this->logger->debug('readAttribute: ' . $dn . ' found', ['app' => 'user_ldap']);
+            return true;
+        }
+        $er = $this->invokeLDAPMethod('firstEntry', $rr);
+        if (!$this->ldap->isResource($er)) {
+            //did not match the filter, return false
+            return false;
+        }
+        //LDAP attributes are not case sensitive
+        $result = \OCP\Util::mb_array_change_key_case(
+            $this->invokeLDAPMethod('getAttributes', $er), MB_CASE_LOWER, 'UTF-8');
+
+        return $result;
+    }
+
+    /**
+     * Normalizes a result grom getAttributes(), i.e. handles DNs and binary
+     * data if present.
+     *
+     * @param array $result from ILDAPWrapper::getAttributes()
+     * @param string $attribute the attribute name that was read
+     * @return string[]
+     */
+    public function extractAttributeValuesFromResult($result, $attribute) {
+        $values = [];
+        if (isset($result[$attribute]) && $result[$attribute]['count'] > 0) {
+            $lowercaseAttribute = strtolower($attribute);
+            for ($i = 0; $i < $result[$attribute]['count']; $i++) {
+                if ($this->resemblesDN($attribute)) {
+                    $values[] = $this->helper->sanitizeDN($result[$attribute][$i]);
+                } elseif ($lowercaseAttribute === 'objectguid' || $lowercaseAttribute === 'guid') {
+                    $values[] = $this->convertObjectGUID2Str($result[$attribute][$i]);
+                } else {
+                    $values[] = $result[$attribute][$i];
+                }
+            }
+        }
+        return $values;
+    }
+
+    /**
+     * Attempts to find ranged data in a getAttribute results and extracts the
+     * returned values as well as information on the range and full attribute
+     * name for further processing.
+     *
+     * @param array $result from ILDAPWrapper::getAttributes()
+     * @param string $attribute the attribute name that was read. Without ";range=…"
+     * @return array If a range was detected with keys 'values', 'attributeName',
+     *               'attributeFull' and 'rangeHigh', otherwise empty.
+     */
+    public function extractRangeData($result, $attribute) {
+        $keys = array_keys($result);
+        foreach ($keys as $key) {
+            if ($key !== $attribute && strpos((string)$key, $attribute) === 0) {
+                $queryData = explode(';', (string)$key);
+                if (strpos($queryData[1], 'range=') === 0) {
+                    $high = substr($queryData[1], 1 + strpos($queryData[1], '-'));
+                    $data = [
+                        'values' => $result[$key],
+                        'attributeName' => $queryData[0],
+                        'attributeFull' => $key,
+                        'rangeHigh' => $high,
+                    ];
+                    return $data;
+                }
+            }
+        }
+        return [];
+    }
+
+    /**
+     * Set password for an LDAP user identified by a DN
+     *
+     * @param string $userDN the user in question
+     * @param string $password the new password
+     * @return bool
+     * @throws HintException
+     * @throws \Exception
+     */
+    public function setPassword($userDN, $password) {
+        if ((int)$this->connection->turnOnPasswordChange !== 1) {
+            throw new \Exception('LDAP password changes are disabled.');
+        }
+        $cr = $this->connection->getConnectionResource();
+        if (!$this->ldap->isResource($cr)) {
+            //LDAP not available
+            $this->logger->debug('LDAP resource not available.', ['app' => 'user_ldap']);
+            return false;
+        }
+        try {
+            // try PASSWD extended operation first
+            return @$this->invokeLDAPMethod('exopPasswd', $userDN, '', $password) ||
+                @$this->invokeLDAPMethod('modReplace', $userDN, $password);
+        } catch (ConstraintViolationException $e) {
+            throw new HintException('Password change rejected.', \OC::$server->getL10N('user_ldap')->t('Password change rejected. Hint: ') . $e->getMessage(), (int)$e->getCode());
+        }
+    }
+
+    /**
+     * checks whether the given attributes value is probably a DN
+     *
+     * @param string $attr the attribute in question
+     * @return boolean if so true, otherwise false
+     */
+    private function resemblesDN($attr) {
+        $resemblingAttributes = [
+            'dn',
+            'uniquemember',
+            'member',
+            // memberOf is an "operational" attribute, without a definition in any RFC
+            'memberof'
+        ];
+        return in_array($attr, $resemblingAttributes);
+    }
+
+    /**
+     * checks whether the given string is probably a DN
+     *
+     * @param string $string
+     * @return boolean
+     */
+    public function stringResemblesDN($string) {
+        $r = $this->ldap->explodeDN($string, 0);
+        // if exploding a DN succeeds and does not end up in
+        // an empty array except for $r[count] being 0.
+        return (is_array($r) && count($r) > 1);
+    }
+
+    /**
+     * returns a DN-string that is cleaned from not domain parts, e.g.
+     * cn=foo,cn=bar,dc=foobar,dc=server,dc=org
+     * becomes dc=foobar,dc=server,dc=org
+     *
+     * @param string $dn
+     * @return string
+     */
+    public function getDomainDNFromDN($dn) {
+        $allParts = $this->ldap->explodeDN($dn, 0);
+        if ($allParts === false) {
+            //not a valid DN
+            return '';
+        }
+        $domainParts = [];
+        $dcFound = false;
+        foreach ($allParts as $part) {
+            if (!$dcFound && strpos($part, 'dc=') === 0) {
+                $dcFound = true;
+            }
+            if ($dcFound) {
+                $domainParts[] = $part;
+            }
+        }
+        return implode(',', $domainParts);
+    }
+
+    /**
+     * returns the LDAP DN for the given internal Nextcloud name of the group
+     *
+     * @param string $name the Nextcloud name in question
+     * @return string|false LDAP DN on success, otherwise false
+     */
+    public function groupname2dn($name) {
+        return $this->getGroupMapper()->getDNByName($name);
+    }
+
+    /**
+     * returns the LDAP DN for the given internal Nextcloud name of the user
+     *
+     * @param string $name the Nextcloud name in question
+     * @return string|false with the LDAP DN on success, otherwise false
+     */
+    public function username2dn($name) {
+        $fdn = $this->getUserMapper()->getDNByName($name);
+
+        //Check whether the DN belongs to the Base, to avoid issues on multi-
+        //server setups
+        if (is_string($fdn) && $this->isDNPartOfBase($fdn, $this->connection->ldapBaseUsers)) {
+            return $fdn;
+        }
+
+        return false;
+    }
+
+    /**
+     * returns the internal Nextcloud name for the given LDAP DN of the group, false on DN outside of search DN or failure
+     *
+     * @param string $fdn the dn of the group object
+     * @param string $ldapName optional, the display name of the object
+     * @return string|false with the name to use in Nextcloud, false on DN outside of search DN
+     * @throws \Exception
+     */
+    public function dn2groupname($fdn, $ldapName = null) {
+        //To avoid bypassing the base DN settings under certain circumstances
+        //with the group support, check whether the provided DN matches one of
+        //the given Bases
+        if (!$this->isDNPartOfBase($fdn, $this->connection->ldapBaseGroups)) {
+            return false;
+        }
+
+        return $this->dn2ocname($fdn, $ldapName, false);
+    }
+
+    /**
+     * returns the internal Nextcloud name for the given LDAP DN of the user, false on DN outside of search DN or failure
+     *
+     * @param string $fdn the dn of the user object
+     * @param string $ldapName optional, the display name of the object
+     * @return string|false with with the name to use in Nextcloud
+     * @throws \Exception
+     */
+    public function dn2username($fdn, $ldapName = null) {
+        //To avoid bypassing the base DN settings under certain circumstances
+        //with the group support, check whether the provided DN matches one of
+        //the given Bases
+        if (!$this->isDNPartOfBase($fdn, $this->connection->ldapBaseUsers)) {
+            return false;
+        }
+
+        return $this->dn2ocname($fdn, $ldapName, true);
+    }
+
+    /**
+     * returns an internal Nextcloud name for the given LDAP DN, false on DN outside of search DN
+     *
+     * @param string $fdn the dn of the user object
+     * @param string|null $ldapName optional, the display name of the object
+     * @param bool $isUser optional, whether it is a user object (otherwise group assumed)
+     * @param bool|null $newlyMapped
+     * @param array|null $record
+     * @return false|string with with the name to use in Nextcloud
+     * @throws \Exception
+     */
+    public function dn2ocname($fdn, $ldapName = null, $isUser = true, &$newlyMapped = null, array $record = null) {
+        static $intermediates = [];
+        if (isset($intermediates[($isUser ? 'user-' : 'group-') . $fdn])) {
+            return false; // is a known intermediate
+        }
+
+        $newlyMapped = false;
+        if ($isUser) {
+            $mapper = $this->getUserMapper();
+            $nameAttribute = $this->connection->ldapUserDisplayName;
+            $filter = $this->connection->ldapUserFilter;
+        } else {
+            $mapper = $this->getGroupMapper();
+            $nameAttribute = $this->connection->ldapGroupDisplayName;
+            $filter = $this->connection->ldapGroupFilter;
+        }
+
+        //let's try to retrieve the Nextcloud name from the mappings table
+        $ncName = $mapper->getNameByDN($fdn);
+        if (is_string($ncName)) {
+            return $ncName;
+        }
+
+        //second try: get the UUID and check if it is known. Then, update the DN and return the name.
+        $uuid = $this->getUUID($fdn, $isUser, $record);
+        if (is_string($uuid)) {
+            $ncName = $mapper->getNameByUUID($uuid);
+            if (is_string($ncName)) {
+                $mapper->setDNbyUUID($fdn, $uuid);
+                return $ncName;
+            }
+        } else {
+            //If the UUID can't be detected something is foul.
+            $this->logger->debug('Cannot determine UUID for ' . $fdn . '. Skipping.', ['app' => 'user_ldap']);
+            return false;
+        }
+
+        if (is_null($ldapName)) {
+            $ldapName = $this->readAttribute($fdn, $nameAttribute, $filter);
+            if (!isset($ldapName[0]) || empty($ldapName[0])) {
+                $this->logger->debug('No or empty name for ' . $fdn . ' with filter ' . $filter . '.', ['app' => 'user_ldap']);
+                $intermediates[($isUser ? 'user-' : 'group-') . $fdn] = true;
+                return false;
+            }
+            $ldapName = $ldapName[0];
+        }
+
+        if ($isUser) {
+            $usernameAttribute = (string)$this->connection->ldapExpertUsernameAttr;
+            if ($usernameAttribute !== '') {
+                $username = $this->readAttribute($fdn, $usernameAttribute);
+                if (!isset($username[0]) || empty($username[0])) {
+                    $this->logger->debug('No or empty username (' . $usernameAttribute . ') for ' . $fdn . '.', ['app' => 'user_ldap']);
+                    return false;
+                }
+                $username = $username[0];
+            } else {
+                $username = $uuid;
+            }
+            try {
+                $intName = $this->sanitizeUsername($username);
+            } catch (\InvalidArgumentException $e) {
+                $this->logger->warning('Error sanitizing username: ' . $e->getMessage(), [
+                    'exception' => $e,
+                ]);
+                // we don't attempt to set a username here. We can go for
+                // for an alternative 4 digit random number as we would append
+                // otherwise, however it's likely not enough space in bigger
+                // setups, and most importantly: this is not intended.
+                return false;
+            }
+        } else {
+            $intName = $this->sanitizeGroupIDCandidate($ldapName);
+        }
+
+        //a new user/group! Add it only if it doesn't conflict with other backend's users or existing groups
+        //disabling Cache is required to avoid that the new user is cached as not-existing in fooExists check
+        //NOTE: mind, disabling cache affects only this instance! Using it
+        // outside of core user management will still cache the user as non-existing.
+        $originalTTL = $this->connection->ldapCacheTTL;
+        $this->connection->setConfiguration(['ldapCacheTTL' => 0]);
+        if ($intName !== ''
+            && (($isUser && !$this->ncUserManager->userExists($intName))
+                || (!$isUser && !\OC::$server->getGroupManager()->groupExists($intName))
+            )
+        ) {
+            $this->connection->setConfiguration(['ldapCacheTTL' => $originalTTL]);
+            $newlyMapped = $this->mapAndAnnounceIfApplicable($mapper, $fdn, $intName, $uuid, $isUser);
+            if ($newlyMapped) {
+                return $intName;
+            }
+        }
+
+        $this->connection->setConfiguration(['ldapCacheTTL' => $originalTTL]);
+        $altName = $this->createAltInternalOwnCloudName($intName, $isUser);
+        if (is_string($altName)) {
+            if ($this->mapAndAnnounceIfApplicable($mapper, $fdn, $altName, $uuid, $isUser)) {
+                $this->logger->warning(
+                    'Mapped {fdn} as {altName} because of a name collision on {intName}.',
+                    [
+                        'fdn' => $fdn,
+                        'altName' => $altName,
+                        'intName' => $intName,
+                        'app' => 'user_ldap',
+                    ]
+                );
+                $newlyMapped = true;
+                return $altName;
+            }
+        }
+
+        //if everything else did not help..
+        $this->logger->info('Could not create unique name for ' . $fdn . '.', ['app' => 'user_ldap']);
+        return false;
+    }
+
+    public function mapAndAnnounceIfApplicable(
+        AbstractMapping $mapper,
+        string $fdn,
+        string $name,
+        string $uuid,
+        bool $isUser
+    ): bool {
+        if ($mapper->map($fdn, $name, $uuid)) {
+            if ($this->ncUserManager instanceof PublicEmitter && $isUser) {
+                $this->cacheUserExists($name);
+                $this->ncUserManager->emit('\OC\User', 'assignedUserId', [$name]);
+            } elseif (!$isUser) {
+                $this->cacheGroupExists($name);
+            }
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * gives back the user names as they are used ownClod internally
+     *
+     * @param array $ldapUsers as returned by fetchList()
+     * @return array an array with the user names to use in Nextcloud
+     *
+     * gives back the user names as they are used ownClod internally
+     * @throws \Exception
+     */
+    public function nextcloudUserNames($ldapUsers) {
+        return $this->ldap2NextcloudNames($ldapUsers, true);
+    }
+
+    /**
+     * gives back the group names as they are used ownClod internally
+     *
+     * @param array $ldapGroups as returned by fetchList()
+     * @return array an array with the group names to use in Nextcloud
+     *
+     * gives back the group names as they are used ownClod internally
+     * @throws \Exception
+     */
+    public function nextcloudGroupNames($ldapGroups) {
+        return $this->ldap2NextcloudNames($ldapGroups, false);
+    }
+
+    /**
+     * @param array[] $ldapObjects as returned by fetchList()
+     * @throws \Exception
+     */
+    private function ldap2NextcloudNames(array $ldapObjects, bool $isUsers): array {
+        if ($isUsers) {
+            $nameAttribute = $this->connection->ldapUserDisplayName;
+            $sndAttribute = $this->connection->ldapUserDisplayName2;
+        } else {
+            $nameAttribute = $this->connection->ldapGroupDisplayName;
+            $sndAttribute = null;
+        }
+        $nextcloudNames = [];
+
+        foreach ($ldapObjects as $ldapObject) {
+            $nameByLDAP = $ldapObject[$nameAttribute][0] ?? null;
+
+            $ncName = $this->dn2ocname($ldapObject['dn'][0], $nameByLDAP, $isUsers);
+            if ($ncName) {
+                $nextcloudNames[] = $ncName;
+                if ($isUsers) {
+                    $this->updateUserState($ncName);
+                    //cache the user names so it does not need to be retrieved
+                    //again later (e.g. sharing dialogue).
+                    if (is_null($nameByLDAP)) {
+                        continue;
+                    }
+                    $sndName = $ldapObject[$sndAttribute][0] ?? '';
+                    $this->cacheUserDisplayName($ncName, $nameByLDAP, $sndName);
+                } elseif ($nameByLDAP !== null) {
+                    $this->cacheGroupDisplayName($ncName, $nameByLDAP);
+                }
+            }
+        }
+        return $nextcloudNames;
+    }
+
+    /**
+     * removes the deleted-flag of a user if it was set
+     *
+     * @param string $ncname
+     * @throws \Exception
+     */
+    public function updateUserState($ncname): void {
+        $user = $this->userManager->get($ncname);
+        if ($user instanceof OfflineUser) {
+            $user->unmark();
+        }
+    }
+
+    /**
+     * caches the user display name
+     *
+     * @param string $ocName the internal Nextcloud username
+     * @param string|false $home the home directory path
+     */
+    public function cacheUserHome(string $ocName, $home): void {
+        $cacheKey = 'getHome' . $ocName;
+        $this->connection->writeToCache($cacheKey, $home);
+    }
+
+    /**
+     * caches a user as existing
+     */
+    public function cacheUserExists(string $ocName): void {
+        $this->connection->writeToCache('userExists' . $ocName, true);
+    }
+
+    /**
+     * caches a group as existing
+     */
+    public function cacheGroupExists(string $gid): void {
+        $this->connection->writeToCache('groupExists' . $gid, true);
+    }
+
+    /**
+     * caches the user display name
+     *
+     * @param string $ocName the internal Nextcloud username
+     * @param string $displayName the display name
+     * @param string $displayName2 the second display name
+     * @throws \Exception
+     */
+    public function cacheUserDisplayName(string $ocName, string $displayName, string $displayName2 = ''): void {
+        $user = $this->userManager->get($ocName);
+        if ($user === null) {
+            return;
+        }
+        $displayName = $user->composeAndStoreDisplayName($displayName, $displayName2);
+        $cacheKeyTrunk = 'getDisplayName';
+        $this->connection->writeToCache($cacheKeyTrunk . $ocName, $displayName);
+    }
+
+    public function cacheGroupDisplayName(string $ncName, string $displayName): void {
+        $cacheKey = 'group_getDisplayName' . $ncName;
+        $this->connection->writeToCache($cacheKey, $displayName);
+    }
+
+    /**
+     * creates a unique name for internal Nextcloud use for users. Don't call it directly.
+     *
+     * @param string $name the display name of the object
+     * @return string|false with with the name to use in Nextcloud or false if unsuccessful
+     *
+     * Instead of using this method directly, call
+     * createAltInternalOwnCloudName($name, true)
+     */
+    private function _createAltInternalOwnCloudNameForUsers(string $name) {
+        $attempts = 0;
+        //while loop is just a precaution. If a name is not generated within
+        //20 attempts, something else is very wrong. Avoids infinite loop.
+        while ($attempts < 20) {
+            $altName = $name . '_' . rand(1000, 9999);
+            if (!$this->ncUserManager->userExists($altName)) {
+                return $altName;
+            }
+            $attempts++;
+        }
+        return false;
+    }
+
+    /**
+     * creates a unique name for internal Nextcloud use for groups. Don't call it directly.
+     *
+     * @param string $name the display name of the object
+     * @return string|false with with the name to use in Nextcloud or false if unsuccessful.
+     *
+     * Instead of using this method directly, call
+     * createAltInternalOwnCloudName($name, false)
+     *
+     * Group names are also used as display names, so we do a sequential
+     * numbering, e.g. Developers_42 when there are 41 other groups called
+     * "Developers"
+     */
+    private function _createAltInternalOwnCloudNameForGroups(string $name) {
+        $usedNames = $this->getGroupMapper()->getNamesBySearch($name, "", '_%');
+        if (count($usedNames) === 0) {
+            $lastNo = 1; //will become name_2
+        } else {
+            natsort($usedNames);
+            $lastName = array_pop($usedNames);
+            $lastNo = (int)substr($lastName, strrpos($lastName, '_') + 1);
+        }
+        $altName = $name . '_' . (string)($lastNo + 1);
+        unset($usedNames);
+
+        $attempts = 1;
+        while ($attempts < 21) {
+            // Check to be really sure it is unique
+            // while loop is just a precaution. If a name is not generated within
+            // 20 attempts, something else is very wrong. Avoids infinite loop.
+            if (!\OC::$server->getGroupManager()->groupExists($altName)) {
+                return $altName;
+            }
+            $altName = $name . '_' . ($lastNo + $attempts);
+            $attempts++;
+        }
+        return false;
+    }
+
+    /**
+     * creates a unique name for internal Nextcloud use.
+     *
+     * @param string $name the display name of the object
+     * @param bool $isUser whether name should be created for a user (true) or a group (false)
+     * @return string|false with with the name to use in Nextcloud or false if unsuccessful
+     */
+    private function createAltInternalOwnCloudName(string $name, bool $isUser) {
+        // ensure there is space for the "_1234" suffix
+        if (strlen($name) > 59) {
+            $name = substr($name, 0, 59);
+        }
+
+        $originalTTL = $this->connection->ldapCacheTTL;
+        $this->connection->setConfiguration(['ldapCacheTTL' => 0]);
+        if ($isUser) {
+            $altName = $this->_createAltInternalOwnCloudNameForUsers($name);
+        } else {
+            $altName = $this->_createAltInternalOwnCloudNameForGroups($name);
+        }
+        $this->connection->setConfiguration(['ldapCacheTTL' => $originalTTL]);
+
+        return $altName;
+    }
+
+    /**
+     * fetches a list of users according to a provided loginName and utilizing
+     * the login filter.
+     */
+    public function fetchUsersByLoginName(string $loginName, array $attributes = ['dn']): array {
+        $loginName = $this->escapeFilterPart($loginName);
+        $filter = str_replace('%uid', $loginName, $this->connection->ldapLoginFilter);
+        return $this->fetchListOfUsers($filter, $attributes);
+    }
+
+    /**
+     * counts the number of users according to a provided loginName and
+     * utilizing the login filter.
+     *
+     * @param string $loginName
+     * @return false|int
+     */
+    public function countUsersByLoginName($loginName) {
+        $loginName = $this->escapeFilterPart($loginName);
+        $filter = str_replace('%uid', $loginName, $this->connection->ldapLoginFilter);
+        return $this->countUsers($filter);
+    }
+
+    /**
+     * @throws \Exception
+     */
+    public function fetchListOfUsers(string $filter, array $attr, int $limit = null, int $offset = null, bool $forceApplyAttributes = false): array {
+        $ldapRecords = $this->searchUsers($filter, $attr, $limit, $offset);
+        $recordsToUpdate = $ldapRecords;
+        if (!$forceApplyAttributes) {
+            $isBackgroundJobModeAjax = $this->config
+                    ->getAppValue('core', 'backgroundjobs_mode', 'ajax') === 'ajax';
+            $listOfDNs = array_reduce($ldapRecords, function ($listOfDNs, $entry) {
+                $listOfDNs[] = $entry['dn'][0];
+                return $listOfDNs;
+            }, []);
+            $idsByDn = $this->getUserMapper()->getListOfIdsByDn($listOfDNs);
+            $recordsToUpdate = array_filter($ldapRecords, function ($record) use ($isBackgroundJobModeAjax, $idsByDn) {
+                $newlyMapped = false;
+                $uid = $idsByDn[$record['dn'][0]] ?? null;
+                if ($uid === null) {
+                    $uid = $this->dn2ocname($record['dn'][0], null, true, $newlyMapped, $record);
+                }
+                if (is_string($uid)) {
+                    $this->cacheUserExists($uid);
+                }
+                return ($uid !== false) && ($newlyMapped || $isBackgroundJobModeAjax);
+            });
+        }
+        $this->batchApplyUserAttributes($recordsToUpdate);
+        return $this->fetchList($ldapRecords, $this->manyAttributes($attr));
+    }
+
+    /**
+     * provided with an array of LDAP user records the method will fetch the
+     * user object and requests it to process the freshly fetched attributes and
+     * and their values
+     *
+     * @throws \Exception
+     */
+    public function batchApplyUserAttributes(array $ldapRecords): void {
+        $displayNameAttribute = strtolower((string)$this->connection->ldapUserDisplayName);
+        foreach ($ldapRecords as $userRecord) {
+            if (!isset($userRecord[$displayNameAttribute])) {
+                // displayName is obligatory
+                continue;
+            }
+            $ocName = $this->dn2ocname($userRecord['dn'][0], null, true);
+            if ($ocName === false) {
+                continue;
+            }
+            $this->updateUserState($ocName);
+            $user = $this->userManager->get($ocName);
+            if ($user !== null) {
+                $user->processAttributes($userRecord);
+            } else {
+                $this->logger->debug(
+                    "The ldap user manager returned null for $ocName",
+                    ['app' => 'user_ldap']
+                );
+            }
+        }
+    }
+
+    /**
+     * @return array[]
+     */
+    public function fetchListOfGroups(string $filter, array $attr, int $limit = null, int $offset = null): array {
+        $cacheKey = 'fetchListOfGroups_' . $filter . '_' . implode('-', $attr) . '_' . (string)$limit . '_' . (string)$offset;
+        $listOfGroups = $this->connection->getFromCache($cacheKey);
+        if (!is_null($listOfGroups)) {
+            return $listOfGroups;
+        }
+        $groupRecords = $this->searchGroups($filter, $attr, $limit, $offset);
+
+        $listOfDNs = array_reduce($groupRecords, function ($listOfDNs, $entry) {
+            $listOfDNs[] = $entry['dn'][0];
+            return $listOfDNs;
+        }, []);
+        $idsByDn = $this->getGroupMapper()->getListOfIdsByDn($listOfDNs);
+
+        array_walk($groupRecords, function (array $record) use ($idsByDn) {
+            $newlyMapped = false;
+            $gid = $idsByDn[$record['dn'][0]] ?? null;
+            if ($gid === null) {
+                $gid = $this->dn2ocname($record['dn'][0], null, false, $newlyMapped, $record);
+            }
+            if (!$newlyMapped && is_string($gid)) {
+                $this->cacheGroupExists($gid);
+            }
+        });
+        $listOfGroups = $this->fetchList($groupRecords, $this->manyAttributes($attr));
+        $this->connection->writeToCache($cacheKey, $listOfGroups);
+        return $listOfGroups;
+    }
+
+    private function fetchList(array $list, bool $manyAttributes): array {
+        if ($manyAttributes) {
+            return $list;
+        } else {
+            $list = array_reduce($list, function ($carry, $item) {
+                $attribute = array_keys($item)[0];
+                $carry[] = $item[$attribute][0];
+                return $carry;
+            }, []);
+            return array_unique($list, SORT_LOCALE_STRING);
+        }
+    }
+
+    /**
+     * @throws ServerNotAvailableException
+     */
+    public function searchUsers(string $filter, array $attr = null, int $limit = null, int $offset = null): array {
+        $result = [];
+        foreach ($this->connection->ldapBaseUsers as $base) {
+            $result = array_merge($result, $this->search($filter, $base, $attr, $limit, $offset));
+        }
+        return $result;
+    }
+
+    /**
+     * @param string[] $attr
+     * @return false|int
+     * @throws ServerNotAvailableException
+     */
+    public function countUsers(string $filter, array $attr = ['dn'], int $limit = null, int $offset = null) {
+        $result = false;
+        foreach ($this->connection->ldapBaseUsers as $base) {
+            $count = $this->count($filter, [$base], $attr, $limit ?? 0, $offset ?? 0);
+            $result = is_int($count) ? (int)$result + $count : $result;
+        }
+        return $result;
+    }
+
+    /**
+     * executes an LDAP search, optimized for Groups
+     *
+     * @param ?string[] $attr optional, when certain attributes shall be filtered out
+     *
+     * Executes an LDAP search
+     * @throws ServerNotAvailableException
+     */
+    public function searchGroups(string $filter, array $attr = null, int $limit = null, int $offset = null): array {
+        $result = [];
+        foreach ($this->connection->ldapBaseGroups as $base) {
+            $result = array_merge($result, $this->search($filter, $base, $attr, $limit, $offset));
+        }
+        return $result;
+    }
+
+    /**
+     * returns the number of available groups
+     *
+     * @return int|bool
+     * @throws ServerNotAvailableException
+     */
+    public function countGroups(string $filter, array $attr = ['dn'], int $limit = null, int $offset = null) {
+        $result = false;
+        foreach ($this->connection->ldapBaseGroups as $base) {
+            $count = $this->count($filter, [$base], $attr, $limit ?? 0, $offset ?? 0);
+            $result = is_int($count) ? (int)$result + $count : $result;
+        }
+        return $result;
+    }
+
+    /**
+     * returns the number of available objects on the base DN
+     *
+     * @return int|bool
+     * @throws ServerNotAvailableException
+     */
+    public function countObjects(int $limit = null, int $offset = null) {
+        $result = false;
+        foreach ($this->connection->ldapBase as $base) {
+            $count = $this->count('objectclass=*', [$base], ['dn'], $limit ?? 0, $offset ?? 0);
+            $result = is_int($count) ? (int)$result + $count : $result;
+        }
+        return $result;
+    }
+
+    /**
+     * Returns the LDAP handler
+     *
+     * @throws \OC\ServerNotAvailableException
+     */
+
+    /**
+     * @param mixed[] $arguments
+     * @return mixed
+     * @throws \OC\ServerNotAvailableException
+     */
+    private function invokeLDAPMethod(string $command, ...$arguments) {
+        if ($command == 'controlPagedResultResponse') {
+            // php no longer supports call-time pass-by-reference
+            // thus cannot support controlPagedResultResponse as the third argument
+            // is a reference
+            throw new \InvalidArgumentException('Invoker does not support controlPagedResultResponse, call LDAP Wrapper directly instead.');
+        }
+        if (!method_exists($this->ldap, $command)) {
+            return null;
+        }
+        array_unshift($arguments, $this->connection->getConnectionResource());
+        $doMethod = function () use ($command, &$arguments) {
+            return call_user_func_array([$this->ldap, $command], $arguments);
+        };
+        try {
+            $ret = $doMethod();
+        } catch (ServerNotAvailableException $e) {
+            /* Server connection lost, attempt to reestablish it
 			 * Maybe implement exponential backoff?
 			 * This was enough to get solr indexer working which has large delays between LDAP fetches.
 			 */
-			$this->logger->debug("Connection lost on $command, attempting to reestablish.", ['app' => 'user_ldap']);
-			$this->connection->resetConnectionResource();
-			$cr = $this->connection->getConnectionResource();
-
-			if (!$this->ldap->isResource($cr)) {
-				// Seems like we didn't find any resource.
-				$this->logger->debug("Could not $command, because resource is missing.", ['app' => 'user_ldap']);
-				throw $e;
-			}
-
-			$arguments[0] = $cr;
-			$ret = $doMethod();
-		}
-		return $ret;
-	}
-
-	/**
-	 * retrieved. Results will according to the order in the array.
-	 *
-	 * @param string $filter
-	 * @param string $base
-	 * @param string[] $attr
-	 * @param int|null $limit optional, maximum results to be counted
-	 * @param int|null $offset optional, a starting point
-	 * @return array|false array with the search result as first value and pagedSearchOK as
-	 * second | false if not successful
-	 * @throws ServerNotAvailableException
-	 */
-	private function executeSearch(
-		string $filter,
-		string $base,
-		?array &$attr,
-		?int $pageSize,
-		?int $offset
-	) {
-		// See if we have a resource, in case not cancel with message
-		$cr = $this->connection->getConnectionResource();
-		if (!$this->ldap->isResource($cr)) {
-			// Seems like we didn't find any resource.
-			// Return an empty array just like before.
-			$this->logger->debug('Could not search, because resource is missing.', ['app' => 'user_ldap']);
-			return false;
-		}
-
-		//check whether paged search should be attempted
-		try {
-			[$pagedSearchOK, $pageSize, $cookie] = $this->initPagedSearch($filter, $base, $attr, (int)$pageSize, (int)$offset);
-		} catch (NoMoreResults $e) {
-			// beyond last results page
-			return false;
-		}
-
-		$sr = $this->invokeLDAPMethod('search', $base, $filter, $attr, 0, 0, $pageSize, $cookie);
-		$error = $this->ldap->errno($this->connection->getConnectionResource());
-		if (!$this->ldap->isResource($sr) || $error !== 0) {
-			$this->logger->error('Attempt for Paging?  ' . print_r($pagedSearchOK, true), ['app' => 'user_ldap']);
-			return false;
-		}
-
-		return [$sr, $pagedSearchOK];
-	}
-
-	/**
-	 * processes an LDAP paged search operation
-	 *
-	 * @param resource|\LDAP\Result|resource[]|\LDAP\Result[] $sr the array containing the LDAP search resources
-	 * @param int $foundItems number of results in the single search operation
-	 * @param int $limit maximum results to be counted
-	 * @param bool $pagedSearchOK whether a paged search has been executed
-	 * @param bool $skipHandling required for paged search when cookies to
-	 * prior results need to be gained
-	 * @return bool cookie validity, true if we have more pages, false otherwise.
-	 * @throws ServerNotAvailableException
-	 */
-	private function processPagedSearchStatus(
-		$sr,
-		int $foundItems,
-		int $limit,
-		bool $pagedSearchOK,
-		bool $skipHandling
-	): bool {
-		$cookie = '';
-		if ($pagedSearchOK) {
-			$cr = $this->connection->getConnectionResource();
-			if ($this->ldap->controlPagedResultResponse($cr, $sr, $cookie)) {
-				$this->lastCookie = $cookie;
-			}
-
-			//browsing through prior pages to get the cookie for the new one
-			if ($skipHandling) {
-				return false;
-			}
-			// if count is bigger, then the server does not support
-			// paged search. Instead, he did a normal search. We set a
-			// flag here, so the callee knows how to deal with it.
-			if ($foundItems <= $limit) {
-				$this->pagedSearchedSuccessful = true;
-			}
-		} else {
-			if ((int)$this->connection->ldapPagingSize !== 0) {
-				$this->logger->debug(
-					'Paged search was not available',
-					['app' => 'user_ldap']
-				);
-			}
-		}
-		/* ++ Fixing RHDS searches with pages with zero results ++
+            $this->logger->debug("Connection lost on $command, attempting to reestablish.", ['app' => 'user_ldap']);
+            $this->connection->resetConnectionResource();
+            $cr = $this->connection->getConnectionResource();
+
+            if (!$this->ldap->isResource($cr)) {
+                // Seems like we didn't find any resource.
+                $this->logger->debug("Could not $command, because resource is missing.", ['app' => 'user_ldap']);
+                throw $e;
+            }
+
+            $arguments[0] = $cr;
+            $ret = $doMethod();
+        }
+        return $ret;
+    }
+
+    /**
+     * retrieved. Results will according to the order in the array.
+     *
+     * @param string $filter
+     * @param string $base
+     * @param string[] $attr
+     * @param int|null $limit optional, maximum results to be counted
+     * @param int|null $offset optional, a starting point
+     * @return array|false array with the search result as first value and pagedSearchOK as
+     * second | false if not successful
+     * @throws ServerNotAvailableException
+     */
+    private function executeSearch(
+        string $filter,
+        string $base,
+        ?array &$attr,
+        ?int $pageSize,
+        ?int $offset
+    ) {
+        // See if we have a resource, in case not cancel with message
+        $cr = $this->connection->getConnectionResource();
+        if (!$this->ldap->isResource($cr)) {
+            // Seems like we didn't find any resource.
+            // Return an empty array just like before.
+            $this->logger->debug('Could not search, because resource is missing.', ['app' => 'user_ldap']);
+            return false;
+        }
+
+        //check whether paged search should be attempted
+        try {
+            [$pagedSearchOK, $pageSize, $cookie] = $this->initPagedSearch($filter, $base, $attr, (int)$pageSize, (int)$offset);
+        } catch (NoMoreResults $e) {
+            // beyond last results page
+            return false;
+        }
+
+        $sr = $this->invokeLDAPMethod('search', $base, $filter, $attr, 0, 0, $pageSize, $cookie);
+        $error = $this->ldap->errno($this->connection->getConnectionResource());
+        if (!$this->ldap->isResource($sr) || $error !== 0) {
+            $this->logger->error('Attempt for Paging?  ' . print_r($pagedSearchOK, true), ['app' => 'user_ldap']);
+            return false;
+        }
+
+        return [$sr, $pagedSearchOK];
+    }
+
+    /**
+     * processes an LDAP paged search operation
+     *
+     * @param resource|\LDAP\Result|resource[]|\LDAP\Result[] $sr the array containing the LDAP search resources
+     * @param int $foundItems number of results in the single search operation
+     * @param int $limit maximum results to be counted
+     * @param bool $pagedSearchOK whether a paged search has been executed
+     * @param bool $skipHandling required for paged search when cookies to
+     * prior results need to be gained
+     * @return bool cookie validity, true if we have more pages, false otherwise.
+     * @throws ServerNotAvailableException
+     */
+    private function processPagedSearchStatus(
+        $sr,
+        int $foundItems,
+        int $limit,
+        bool $pagedSearchOK,
+        bool $skipHandling
+    ): bool {
+        $cookie = '';
+        if ($pagedSearchOK) {
+            $cr = $this->connection->getConnectionResource();
+            if ($this->ldap->controlPagedResultResponse($cr, $sr, $cookie)) {
+                $this->lastCookie = $cookie;
+            }
+
+            //browsing through prior pages to get the cookie for the new one
+            if ($skipHandling) {
+                return false;
+            }
+            // if count is bigger, then the server does not support
+            // paged search. Instead, he did a normal search. We set a
+            // flag here, so the callee knows how to deal with it.
+            if ($foundItems <= $limit) {
+                $this->pagedSearchedSuccessful = true;
+            }
+        } else {
+            if ((int)$this->connection->ldapPagingSize !== 0) {
+                $this->logger->debug(
+                    'Paged search was not available',
+                    ['app' => 'user_ldap']
+                );
+            }
+        }
+        /* ++ Fixing RHDS searches with pages with zero results ++
 		 * Return cookie status. If we don't have more pages, with RHDS
 		 * cookie is null, with openldap cookie is an empty string and
 		 * to 386ds '0' is a valid cookie. Even if $iFoundItems == 0
 		 */
-		return !empty($cookie) || $cookie === '0';
-	}
-
-	/**
-	 * executes an LDAP search, but counts the results only
-	 *
-	 * @param string $filter the LDAP filter for the search
-	 * @param array $bases an array containing the LDAP subtree(s) that shall be searched
-	 * @param ?string[] $attr optional, array, one or more attributes that shall be
-	 * retrieved. Results will according to the order in the array.
-	 * @param int $limit maximum results to be counted, 0 means no limit
-	 * @param int $offset a starting point, defaults to 0
-	 * @param bool $skipHandling indicates whether the pages search operation is
-	 * completed
-	 * @return int|false Integer or false if the search could not be initialized
-	 * @throws ServerNotAvailableException
-	 */
-	private function count(
-		string $filter,
-		array $bases,
-		array $attr = null,
-		int $limit = 0,
-		int $offset = 0,
-		bool $skipHandling = false
-	) {
-		$this->logger->debug('Count filter: {filter}', [
-			'app' => 'user_ldap',
-			'filter' => $filter
-		]);
-
-		$limitPerPage = (int)$this->connection->ldapPagingSize;
-		if ($limit < $limitPerPage && $limit > 0) {
-			$limitPerPage = $limit;
-		}
-
-		$counter = 0;
-		$count = null;
-		$this->connection->getConnectionResource();
-
-		foreach ($bases as $base) {
-			do {
-				$search = $this->executeSearch($filter, $base, $attr, $limitPerPage, $offset);
-				if ($search === false) {
-					return $counter > 0 ? $counter : false;
-				}
-				[$sr, $pagedSearchOK] = $search;
-
-				/* ++ Fixing RHDS searches with pages with zero results ++
+        return !empty($cookie) || $cookie === '0';
+    }
+
+    /**
+     * executes an LDAP search, but counts the results only
+     *
+     * @param string $filter the LDAP filter for the search
+     * @param array $bases an array containing the LDAP subtree(s) that shall be searched
+     * @param ?string[] $attr optional, array, one or more attributes that shall be
+     * retrieved. Results will according to the order in the array.
+     * @param int $limit maximum results to be counted, 0 means no limit
+     * @param int $offset a starting point, defaults to 0
+     * @param bool $skipHandling indicates whether the pages search operation is
+     * completed
+     * @return int|false Integer or false if the search could not be initialized
+     * @throws ServerNotAvailableException
+     */
+    private function count(
+        string $filter,
+        array $bases,
+        array $attr = null,
+        int $limit = 0,
+        int $offset = 0,
+        bool $skipHandling = false
+    ) {
+        $this->logger->debug('Count filter: {filter}', [
+            'app' => 'user_ldap',
+            'filter' => $filter
+        ]);
+
+        $limitPerPage = (int)$this->connection->ldapPagingSize;
+        if ($limit < $limitPerPage && $limit > 0) {
+            $limitPerPage = $limit;
+        }
+
+        $counter = 0;
+        $count = null;
+        $this->connection->getConnectionResource();
+
+        foreach ($bases as $base) {
+            do {
+                $search = $this->executeSearch($filter, $base, $attr, $limitPerPage, $offset);
+                if ($search === false) {
+                    return $counter > 0 ? $counter : false;
+                }
+                [$sr, $pagedSearchOK] = $search;
+
+                /* ++ Fixing RHDS searches with pages with zero results ++
 				 * countEntriesInSearchResults() method signature changed
 				 * by removing $limit and &$hasHitLimit parameters
 				 */
-				$count = $this->countEntriesInSearchResults($sr);
-				$counter += $count;
+                $count = $this->countEntriesInSearchResults($sr);
+                $counter += $count;
 
-				$hasMorePages = $this->processPagedSearchStatus($sr, $count, $limitPerPage, $pagedSearchOK, $skipHandling);
-				$offset += $limitPerPage;
-				/* ++ Fixing RHDS searches with pages with zero results ++
+                $hasMorePages = $this->processPagedSearchStatus($sr, $count, $limitPerPage, $pagedSearchOK, $skipHandling);
+                $offset += $limitPerPage;
+                /* ++ Fixing RHDS searches with pages with zero results ++
 				 * Continue now depends on $hasMorePages value
 				 */
-				$continue = $pagedSearchOK && $hasMorePages;
-			} while ($continue && ($limit <= 0 || $limit > $counter));
-		}
-
-		return $counter;
-	}
-
-	/**
-	 * @param resource|\LDAP\Result|resource[]|\LDAP\Result[] $sr
-	 * @return int
-	 * @throws ServerNotAvailableException
-	 */
-	private function countEntriesInSearchResults($sr): int {
-		return (int)$this->invokeLDAPMethod('countEntries', $sr);
-	}
-
-	/**
-	 * Executes an LDAP search
-	 *
-	 * @throws ServerNotAvailableException
-	 */
-	public function search(
-		string $filter,
-		string $base,
-		?array $attr = null,
-		?int $limit = null,
-		?int $offset = null,
-		bool $skipHandling = false
-	): array {
-		$limitPerPage = (int)$this->connection->ldapPagingSize;
-		if (!is_null($limit) && $limit < $limitPerPage && $limit > 0) {
-			$limitPerPage = $limit;
-		}
-
-		/* ++ Fixing RHDS searches with pages with zero results ++
+                $continue = $pagedSearchOK && $hasMorePages;
+            } while ($continue && ($limit <= 0 || $limit > $counter));
+        }
+
+        return $counter;
+    }
+
+    /**
+     * @param resource|\LDAP\Result|resource[]|\LDAP\Result[] $sr
+     * @return int
+     * @throws ServerNotAvailableException
+     */
+    private function countEntriesInSearchResults($sr): int {
+        return (int)$this->invokeLDAPMethod('countEntries', $sr);
+    }
+
+    /**
+     * Executes an LDAP search
+     *
+     * @throws ServerNotAvailableException
+     */
+    public function search(
+        string $filter,
+        string $base,
+        ?array $attr = null,
+        ?int $limit = null,
+        ?int $offset = null,
+        bool $skipHandling = false
+    ): array {
+        $limitPerPage = (int)$this->connection->ldapPagingSize;
+        if (!is_null($limit) && $limit < $limitPerPage && $limit > 0) {
+            $limitPerPage = $limit;
+        }
+
+        /* ++ Fixing RHDS searches with pages with zero results ++
 		 * As we can have pages with zero results and/or pages with less
 		 * than $limit results but with a still valid server 'cookie',
 		 * loops through until we get $continue equals true and
 		 * $findings['count'] < $limit
 		 */
-		$findings = [];
-		$offset = $offset ?? 0;
-		$savedoffset = $offset;
-		$iFoundItems = 0;
-
-		do {
-			$search = $this->executeSearch($filter, $base, $attr, $limitPerPage, $offset);
-			if ($search === false) {
-				return [];
-			}
-			[$sr, $pagedSearchOK] = $search;
-
-			if ($skipHandling) {
-				//i.e. result do not need to be fetched, we just need the cookie
-				//thus pass 1 or any other value as $iFoundItems because it is not
-				//used
-				$this->processPagedSearchStatus($sr, 1, $limitPerPage, $pagedSearchOK, $skipHandling);
-				return [];
-			}
-
-			$findings = array_merge($findings, $this->invokeLDAPMethod('getEntries', $sr));
-			$iFoundItems = max($iFoundItems, $findings['count']);
-			unset($findings['count']);
-
-			$continue = $this->processPagedSearchStatus($sr, $iFoundItems, $limitPerPage, $pagedSearchOK, $skipHandling);
-			$offset += $limitPerPage;
-		} while ($continue && $pagedSearchOK && ($limit === null || count($findings) < $limit));
-
-		// resetting offset
-		$offset = $savedoffset;
-
-		if (!is_null($attr)) {
-			$selection = [];
-			$i = 0;
-			foreach ($findings as $item) {
-				if (!is_array($item)) {
-					continue;
-				}
-				$item = \OCP\Util::mb_array_change_key_case($item, MB_CASE_LOWER, 'UTF-8');
-				foreach ($attr as $key) {
-					if (isset($item[$key])) {
-						if (is_array($item[$key]) && isset($item[$key]['count'])) {
-							unset($item[$key]['count']);
-						}
-						if ($key !== 'dn') {
-							if ($this->resemblesDN($key)) {
-								$selection[$i][$key] = $this->helper->sanitizeDN($item[$key]);
-							} elseif ($key === 'objectguid' || $key === 'guid') {
-								$selection[$i][$key] = [$this->convertObjectGUID2Str($item[$key][0])];
-							} else {
-								$selection[$i][$key] = $item[$key];
-							}
-						} else {
-							$selection[$i][$key] = [$this->helper->sanitizeDN($item[$key])];
-						}
-					}
-				}
-				$i++;
-			}
-			$findings = $selection;
-		}
-		//we slice the findings, when
-		//a) paged search unsuccessful, though attempted
-		//b) no paged search, but limit set
-		if ((!$this->getPagedSearchResultState()
-				&& $pagedSearchOK)
-			|| (
-				!$pagedSearchOK
-				&& !is_null($limit)
-			)
-		) {
-			$findings = array_slice($findings, $offset, $limit);
-		}
-		return $findings;
-	}
-
-	/**
-	 * @param string $name
-	 * @return string
-	 * @throws \InvalidArgumentException
-	 */
-	public function sanitizeUsername($name) {
-		$name = trim($name);
-
-		if ($this->connection->ldapIgnoreNamingRules) {
-			return $name;
-		}
-
-		// Use htmlentities to get rid of accents
-		$name = htmlentities($name, ENT_NOQUOTES, 'UTF-8');
-
-		// Remove accents
-		$name = preg_replace('#&([A-Za-z])(?:acute|cedil|caron|circ|grave|orn|ring|slash|th|tilde|uml);#', '\1', $name);
-		// Remove ligatures
-		$name = preg_replace('#&([A-Za-z]{2})(?:lig);#', '\1', $name);
-		// Remove unknown leftover entities
-		$name = preg_replace('#&[^;]+;#', '', $name);
-
-		// Replacements
-		$name = str_replace(' ', '_', $name);
-
-		// Every remaining disallowed characters will be removed
-		$name = preg_replace('/[^a-zA-Z0-9_.@-]/u', '', $name);
-
-		if (strlen($name) > 64) {
-			$name = hash('sha256', $name, false);
-		}
-
-		if ($name === '') {
-			throw new \InvalidArgumentException('provided name template for username does not contain any allowed characters');
-		}
-
-		return $name;
-	}
-
-	public function sanitizeGroupIDCandidate(string $candidate): string {
-		$candidate = trim($candidate);
-		if (strlen($candidate) > 64) {
-			$candidate = hash('sha256', $candidate, false);
-		}
-		if ($candidate === '') {
-			throw new \InvalidArgumentException('provided name template for username does not contain any allowed characters');
-		}
-
-		return $candidate;
-	}
-
-	/**
-	 * escapes (user provided) parts for LDAP filter
-	 *
-	 * @param string $input , the provided value
-	 * @param bool $allowAsterisk whether in * at the beginning should be preserved
-	 * @return string the escaped string
-	 */
-	public function escapeFilterPart($input, $allowAsterisk = false): string {
-		$asterisk = '';
-		if ($allowAsterisk && strlen($input) > 0 && $input[0] === '*') {
-			$asterisk = '*';
-			$input = mb_substr($input, 1, null, 'UTF-8');
-		}
-		$search = ['*', '\\', '(', ')'];
-		$replace = ['\\*', '\\\\', '\\(', '\\)'];
-		return $asterisk . str_replace($search, $replace, $input);
-	}
-
-	/**
-	 * combines the input filters with AND
-	 *
-	 * @param string[] $filters the filters to connect
-	 * @return string the combined filter
-	 */
-	public function combineFilterWithAnd($filters): string {
-		return $this->combineFilter($filters, '&');
-	}
-
-	/**
-	 * combines the input filters with OR
-	 *
-	 * @param string[] $filters the filters to connect
-	 * @return string the combined filter
-	 * Combines Filter arguments with OR
-	 */
-	public function combineFilterWithOr($filters) {
-		return $this->combineFilter($filters, '|');
-	}
-
-	/**
-	 * combines the input filters with given operator
-	 *
-	 * @param string[] $filters the filters to connect
-	 * @param string $operator either & or |
-	 * @return string the combined filter
-	 */
-	private function combineFilter(array $filters, string $operator): string {
-		$combinedFilter = '(' . $operator;
-		foreach ($filters as $filter) {
-			if ($filter !== '' && $filter[0] !== '(') {
-				$filter = '(' . $filter . ')';
-			}
-			$combinedFilter .= $filter;
-		}
-		$combinedFilter .= ')';
-		return $combinedFilter;
-	}
-
-	/**
-	 * creates a filter part for to perform search for users
-	 *
-	 * @param string $search the search term
-	 * @return string the final filter part to use in LDAP searches
-	 */
-	public function getFilterPartForUserSearch($search): string {
-		return $this->getFilterPartForSearch($search,
-			$this->connection->ldapAttributesForUserSearch,
-			$this->connection->ldapUserDisplayName);
-	}
-
-	/**
-	 * creates a filter part for to perform search for groups
-	 *
-	 * @param string $search the search term
-	 * @return string the final filter part to use in LDAP searches
-	 */
-	public function getFilterPartForGroupSearch($search): string {
-		return $this->getFilterPartForSearch($search,
-			$this->connection->ldapAttributesForGroupSearch,
-			$this->connection->ldapGroupDisplayName);
-	}
-
-	/**
-	 * creates a filter part for searches by splitting up the given search
-	 * string into single words
-	 *
-	 * @param string $search the search term
-	 * @param string[]|null|'' $searchAttributes needs to have at least two attributes,
-	 * otherwise it does not make sense :)
-	 * @return string the final filter part to use in LDAP searches
-	 * @throws DomainException
-	 */
-	private function getAdvancedFilterPartForSearch(string $search, $searchAttributes): string {
-		if (!is_array($searchAttributes) || count($searchAttributes) < 2) {
-			throw new DomainException('searchAttributes must be an array with at least two string');
-		}
-		$searchWords = explode(' ', trim($search));
-		$wordFilters = [];
-		foreach ($searchWords as $word) {
-			$word = $this->prepareSearchTerm($word);
-			//every word needs to appear at least once
-			$wordMatchOneAttrFilters = [];
-			foreach ($searchAttributes as $attr) {
-				$wordMatchOneAttrFilters[] = $attr . '=' . $word;
-			}
-			$wordFilters[] = $this->combineFilterWithOr($wordMatchOneAttrFilters);
-		}
-		return $this->combineFilterWithAnd($wordFilters);
-	}
-
-	/**
-	 * creates a filter part for searches
-	 *
-	 * @param string $search the search term
-	 * @param string[]|null|'' $searchAttributes
-	 * @param string $fallbackAttribute a fallback attribute in case the user
-	 * did not define search attributes. Typically the display name attribute.
-	 * @return string the final filter part to use in LDAP searches
-	 */
-	private function getFilterPartForSearch(string $search, $searchAttributes, string $fallbackAttribute): string {
-		$filter = [];
-		$haveMultiSearchAttributes = (is_array($searchAttributes) && count($searchAttributes) > 0);
-		if ($haveMultiSearchAttributes && strpos(trim($search), ' ') !== false) {
-			try {
-				return $this->getAdvancedFilterPartForSearch($search, $searchAttributes);
-			} catch (DomainException $e) {
-				// Creating advanced filter for search failed, falling back to simple method. Edge case, but valid.
-			}
-		}
-
-		$originalSearch = $search;
-		$search = $this->prepareSearchTerm($search);
-		if (!is_array($searchAttributes) || count($searchAttributes) === 0) {
-			if ($fallbackAttribute === '') {
-				return '';
-			}
-			// wildcards don't work with some attributes
-			$filter[] = $fallbackAttribute . '=' . $originalSearch;
-			$filter[] = $fallbackAttribute . '=' . $search;
-		} else {
-			foreach ($searchAttributes as $attribute) {
-				// wildcards don't work with some attributes
-				$filter[] = $attribute . '=' . $originalSearch;
-				$filter[] = $attribute . '=' . $search;
-			}
-		}
-		if (count($filter) === 1) {
-			return '(' . $filter[0] . ')';
-		}
-		return $this->combineFilterWithOr($filter);
-	}
-
-	/**
-	 * returns the search term depending on whether we are allowed
-	 * list users found by ldap with the current input appended by
-	 * a *
-	 */
-	private function prepareSearchTerm(string $term): string {
-		$config = \OC::$server->getConfig();
-
-		$allowEnum = $config->getAppValue('core', 'shareapi_allow_share_dialog_user_enumeration', 'yes');
-
-		$result = $term;
-		if ($term === '') {
-			$result = '*';
-		} elseif ($allowEnum !== 'no') {
-			$result = $term . '*';
-		}
-		return $result;
-	}
-
-	/**
-	 * returns the filter used for counting users
-	 */
-	public function getFilterForUserCount(): string {
-		$filter = $this->combineFilterWithAnd([
-			$this->connection->ldapUserFilter,
-			$this->connection->ldapUserDisplayName . '=*'
-		]);
-
-		return $filter;
-	}
-
-	/**
-	 * @param string $name
-	 * @param string $password
-	 * @return bool
-	 */
-	public function areCredentialsValid($name, $password) {
-		$name = $this->helper->DNasBaseParameter($name);
-		$testConnection = clone $this->connection;
-		$credentials = [
-			'ldapAgentName' => $name,
-			'ldapAgentPassword' => $password
-		];
-		if (!$testConnection->setConfiguration($credentials)) {
-			return false;
-		}
-		return $testConnection->bind();
-	}
-
-	/**
-	 * reverse lookup of a DN given a known UUID
-	 *
-	 * @param string $uuid
-	 * @return string
-	 * @throws \Exception
-	 */
-	public function getUserDnByUuid($uuid) {
-		$uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
-		$filter = $this->connection->ldapUserFilter;
-		$bases = $this->connection->ldapBaseUsers;
-
-		if ($this->connection->ldapUuidUserAttribute === 'auto' && $uuidOverride === '') {
-			// Sacrebleu! The UUID attribute is unknown :( We need first an
-			// existing DN to be able to reliably detect it.
-			foreach ($bases as $base) {
-				$result = $this->search($filter, $base, ['dn'], 1);
-				if (!isset($result[0]) || !isset($result[0]['dn'])) {
-					continue;
-				}
-				$dn = $result[0]['dn'][0];
-				if ($hasFound = $this->detectUuidAttribute($dn, true)) {
-					break;
-				}
-			}
-			if (!isset($hasFound) || !$hasFound) {
-				throw new \Exception('Cannot determine UUID attribute');
-			}
-		} else {
-			// The UUID attribute is either known or an override is given.
-			// By calling this method we ensure that $this->connection->$uuidAttr
-			// is definitely set
-			if (!$this->detectUuidAttribute('', true)) {
-				throw new \Exception('Cannot determine UUID attribute');
-			}
-		}
-
-		$uuidAttr = $this->connection->ldapUuidUserAttribute;
-		if ($uuidAttr === 'guid' || $uuidAttr === 'objectguid') {
-			$uuid = $this->formatGuid2ForFilterUser($uuid);
-		}
-
-		$filter = $uuidAttr . '=' . $uuid;
-		$result = $this->searchUsers($filter, ['dn'], 2);
-		if (isset($result[0]['dn']) && count($result) === 1) {
-			// we put the count into account to make sure that this is
-			// really unique
-			return $result[0]['dn'][0];
-		}
-
-		throw new \Exception('Cannot determine UUID attribute');
-	}
-
-	/**
-	 * auto-detects the directory's UUID attribute
-	 *
-	 * @param string $dn a known DN used to check against
-	 * @param bool $isUser
-	 * @param bool $force the detection should be run, even if it is not set to auto
-	 * @param array|null $ldapRecord
-	 * @return bool true on success, false otherwise
-	 * @throws ServerNotAvailableException
-	 */
-	private function detectUuidAttribute(string $dn, bool $isUser = true, bool $force = false, ?array $ldapRecord = null): bool {
-		if ($isUser) {
-			$uuidAttr = 'ldapUuidUserAttribute';
-			$uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
-		} else {
-			$uuidAttr = 'ldapUuidGroupAttribute';
-			$uuidOverride = $this->connection->ldapExpertUUIDGroupAttr;
-		}
-
-		if (!$force) {
-			if ($this->connection->$uuidAttr !== 'auto') {
-				return true;
-			} elseif (is_string($uuidOverride) && trim($uuidOverride) !== '') {
-				$this->connection->$uuidAttr = $uuidOverride;
-				return true;
-			}
-
-			$attribute = $this->connection->getFromCache($uuidAttr);
-			if ($attribute !== null) {
-				$this->connection->$uuidAttr = $attribute;
-				return true;
-			}
-		}
-
-		foreach (self::UUID_ATTRIBUTES as $attribute) {
-			if ($ldapRecord !== null) {
-				// we have the info from LDAP already, we don't need to talk to the server again
-				if (isset($ldapRecord[$attribute])) {
-					$this->connection->$uuidAttr = $attribute;
-					return true;
-				}
-			}
-
-			$value = $this->readAttribute($dn, $attribute);
-			if (is_array($value) && isset($value[0]) && !empty($value[0])) {
-				$this->logger->debug(
-					'Setting {attribute} as {subject}',
-					[
-						'app' => 'user_ldap',
-						'attribute' => $attribute,
-						'subject' => $uuidAttr
-					]
-				);
-				$this->connection->$uuidAttr = $attribute;
-				$this->connection->writeToCache($uuidAttr, $attribute);
-				return true;
-			}
-		}
-		$this->logger->debug('Could not autodetect the UUID attribute', ['app' => 'user_ldap']);
-
-		return false;
-	}
-
-	/**
-	 * @param array|null $ldapRecord
-	 * @return false|string
-	 * @throws ServerNotAvailableException
-	 */
-	public function getUUID(string $dn, bool $isUser = true, array $ldapRecord = null) {
-		if ($isUser) {
-			$uuidAttr = 'ldapUuidUserAttribute';
-			$uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
-		} else {
-			$uuidAttr = 'ldapUuidGroupAttribute';
-			$uuidOverride = $this->connection->ldapExpertUUIDGroupAttr;
-		}
-
-		$uuid = false;
-		if ($this->detectUuidAttribute($dn, $isUser, false, $ldapRecord)) {
-			$attr = $this->connection->$uuidAttr;
-			$uuid = isset($ldapRecord[$attr]) ? $ldapRecord[$attr] : $this->readAttribute($dn, $attr);
-			if (!is_array($uuid)
-				&& $uuidOverride !== ''
-				&& $this->detectUuidAttribute($dn, $isUser, true, $ldapRecord)) {
-				$uuid = isset($ldapRecord[$this->connection->$uuidAttr])
-					? $ldapRecord[$this->connection->$uuidAttr]
-					: $this->readAttribute($dn, $this->connection->$uuidAttr);
-			}
-			if (is_array($uuid) && !empty($uuid[0])) {
-				$uuid = $uuid[0];
-			}
-		}
-
-		return $uuid;
-	}
-
-	/**
-	 * converts a binary ObjectGUID into a string representation
-	 *
-	 * @param string $oguid the ObjectGUID in its binary form as retrieved from AD
-	 * @link https://www.php.net/manual/en/function.ldap-get-values-len.php#73198
-	 */
-	private function convertObjectGUID2Str(string $oguid): string {
-		$hex_guid = bin2hex($oguid);
-		$hex_guid_to_guid_str = '';
-		for ($k = 1; $k <= 4; ++$k) {
-			$hex_guid_to_guid_str .= substr($hex_guid, 8 - 2 * $k, 2);
-		}
-		$hex_guid_to_guid_str .= '-';
-		for ($k = 1; $k <= 2; ++$k) {
-			$hex_guid_to_guid_str .= substr($hex_guid, 12 - 2 * $k, 2);
-		}
-		$hex_guid_to_guid_str .= '-';
-		for ($k = 1; $k <= 2; ++$k) {
-			$hex_guid_to_guid_str .= substr($hex_guid, 16 - 2 * $k, 2);
-		}
-		$hex_guid_to_guid_str .= '-' . substr($hex_guid, 16, 4);
-		$hex_guid_to_guid_str .= '-' . substr($hex_guid, 20);
-
-		return strtoupper($hex_guid_to_guid_str);
-	}
-
-	/**
-	 * the first three blocks of the string-converted GUID happen to be in
-	 * reverse order. In order to use it in a filter, this needs to be
-	 * corrected. Furthermore the dashes need to be replaced and \\ prepended
-	 * to every two hex figures.
-	 *
-	 * If an invalid string is passed, it will be returned without change.
-	 */
-	public function formatGuid2ForFilterUser(string $guid): string {
-		$blocks = explode('-', $guid);
-		if (count($blocks) !== 5) {
-			/*
+        $findings = [];
+        $offset = $offset ?? 0;
+        $savedoffset = $offset;
+        $iFoundItems = 0;
+
+        do {
+            $search = $this->executeSearch($filter, $base, $attr, $limitPerPage, $offset);
+            if ($search === false) {
+                return [];
+            }
+            [$sr, $pagedSearchOK] = $search;
+
+            if ($skipHandling) {
+                //i.e. result do not need to be fetched, we just need the cookie
+                //thus pass 1 or any other value as $iFoundItems because it is not
+                //used
+                $this->processPagedSearchStatus($sr, 1, $limitPerPage, $pagedSearchOK, $skipHandling);
+                return [];
+            }
+
+            $findings = array_merge($findings, $this->invokeLDAPMethod('getEntries', $sr));
+            $iFoundItems = max($iFoundItems, $findings['count']);
+            unset($findings['count']);
+
+            $continue = $this->processPagedSearchStatus($sr, $iFoundItems, $limitPerPage, $pagedSearchOK, $skipHandling);
+            $offset += $limitPerPage;
+        } while ($continue && $pagedSearchOK && ($limit === null || count($findings) < $limit));
+
+        // resetting offset
+        $offset = $savedoffset;
+
+        if (!is_null($attr)) {
+            $selection = [];
+            $i = 0;
+            foreach ($findings as $item) {
+                if (!is_array($item)) {
+                    continue;
+                }
+                $item = \OCP\Util::mb_array_change_key_case($item, MB_CASE_LOWER, 'UTF-8');
+                foreach ($attr as $key) {
+                    if (isset($item[$key])) {
+                        if (is_array($item[$key]) && isset($item[$key]['count'])) {
+                            unset($item[$key]['count']);
+                        }
+                        if ($key !== 'dn') {
+                            if ($this->resemblesDN($key)) {
+                                $selection[$i][$key] = $this->helper->sanitizeDN($item[$key]);
+                            } elseif ($key === 'objectguid' || $key === 'guid') {
+                                $selection[$i][$key] = [$this->convertObjectGUID2Str($item[$key][0])];
+                            } else {
+                                $selection[$i][$key] = $item[$key];
+                            }
+                        } else {
+                            $selection[$i][$key] = [$this->helper->sanitizeDN($item[$key])];
+                        }
+                    }
+                }
+                $i++;
+            }
+            $findings = $selection;
+        }
+        //we slice the findings, when
+        //a) paged search unsuccessful, though attempted
+        //b) no paged search, but limit set
+        if ((!$this->getPagedSearchResultState()
+                && $pagedSearchOK)
+            || (
+                !$pagedSearchOK
+                && !is_null($limit)
+            )
+        ) {
+            $findings = array_slice($findings, $offset, $limit);
+        }
+        return $findings;
+    }
+
+    /**
+     * @param string $name
+     * @return string
+     * @throws \InvalidArgumentException
+     */
+    public function sanitizeUsername($name) {
+        $name = trim($name);
+
+        if ($this->connection->ldapIgnoreNamingRules) {
+            return $name;
+        }
+
+        // Use htmlentities to get rid of accents
+        $name = htmlentities($name, ENT_NOQUOTES, 'UTF-8');
+
+        // Remove accents
+        $name = preg_replace('#&([A-Za-z])(?:acute|cedil|caron|circ|grave|orn|ring|slash|th|tilde|uml);#', '\1', $name);
+        // Remove ligatures
+        $name = preg_replace('#&([A-Za-z]{2})(?:lig);#', '\1', $name);
+        // Remove unknown leftover entities
+        $name = preg_replace('#&[^;]+;#', '', $name);
+
+        // Replacements
+        $name = str_replace(' ', '_', $name);
+
+        // Every remaining disallowed characters will be removed
+        $name = preg_replace('/[^a-zA-Z0-9_.@-]/u', '', $name);
+
+        if (strlen($name) > 64) {
+            $name = hash('sha256', $name, false);
+        }
+
+        if ($name === '') {
+            throw new \InvalidArgumentException('provided name template for username does not contain any allowed characters');
+        }
+
+        return $name;
+    }
+
+    public function sanitizeGroupIDCandidate(string $candidate): string {
+        $candidate = trim($candidate);
+        if (strlen($candidate) > 64) {
+            $candidate = hash('sha256', $candidate, false);
+        }
+        if ($candidate === '') {
+            throw new \InvalidArgumentException('provided name template for username does not contain any allowed characters');
+        }
+
+        return $candidate;
+    }
+
+    /**
+     * escapes (user provided) parts for LDAP filter
+     *
+     * @param string $input , the provided value
+     * @param bool $allowAsterisk whether in * at the beginning should be preserved
+     * @return string the escaped string
+     */
+    public function escapeFilterPart($input, $allowAsterisk = false): string {
+        $asterisk = '';
+        if ($allowAsterisk && strlen($input) > 0 && $input[0] === '*') {
+            $asterisk = '*';
+            $input = mb_substr($input, 1, null, 'UTF-8');
+        }
+        $search = ['*', '\\', '(', ')'];
+        $replace = ['\\*', '\\\\', '\\(', '\\)'];
+        return $asterisk . str_replace($search, $replace, $input);
+    }
+
+    /**
+     * combines the input filters with AND
+     *
+     * @param string[] $filters the filters to connect
+     * @return string the combined filter
+     */
+    public function combineFilterWithAnd($filters): string {
+        return $this->combineFilter($filters, '&');
+    }
+
+    /**
+     * combines the input filters with OR
+     *
+     * @param string[] $filters the filters to connect
+     * @return string the combined filter
+     * Combines Filter arguments with OR
+     */
+    public function combineFilterWithOr($filters) {
+        return $this->combineFilter($filters, '|');
+    }
+
+    /**
+     * combines the input filters with given operator
+     *
+     * @param string[] $filters the filters to connect
+     * @param string $operator either & or |
+     * @return string the combined filter
+     */
+    private function combineFilter(array $filters, string $operator): string {
+        $combinedFilter = '(' . $operator;
+        foreach ($filters as $filter) {
+            if ($filter !== '' && $filter[0] !== '(') {
+                $filter = '(' . $filter . ')';
+            }
+            $combinedFilter .= $filter;
+        }
+        $combinedFilter .= ')';
+        return $combinedFilter;
+    }
+
+    /**
+     * creates a filter part for to perform search for users
+     *
+     * @param string $search the search term
+     * @return string the final filter part to use in LDAP searches
+     */
+    public function getFilterPartForUserSearch($search): string {
+        return $this->getFilterPartForSearch($search,
+            $this->connection->ldapAttributesForUserSearch,
+            $this->connection->ldapUserDisplayName);
+    }
+
+    /**
+     * creates a filter part for to perform search for groups
+     *
+     * @param string $search the search term
+     * @return string the final filter part to use in LDAP searches
+     */
+    public function getFilterPartForGroupSearch($search): string {
+        return $this->getFilterPartForSearch($search,
+            $this->connection->ldapAttributesForGroupSearch,
+            $this->connection->ldapGroupDisplayName);
+    }
+
+    /**
+     * creates a filter part for searches by splitting up the given search
+     * string into single words
+     *
+     * @param string $search the search term
+     * @param string[]|null|'' $searchAttributes needs to have at least two attributes,
+     * otherwise it does not make sense :)
+     * @return string the final filter part to use in LDAP searches
+     * @throws DomainException
+     */
+    private function getAdvancedFilterPartForSearch(string $search, $searchAttributes): string {
+        if (!is_array($searchAttributes) || count($searchAttributes) < 2) {
+            throw new DomainException('searchAttributes must be an array with at least two string');
+        }
+        $searchWords = explode(' ', trim($search));
+        $wordFilters = [];
+        foreach ($searchWords as $word) {
+            $word = $this->prepareSearchTerm($word);
+            //every word needs to appear at least once
+            $wordMatchOneAttrFilters = [];
+            foreach ($searchAttributes as $attr) {
+                $wordMatchOneAttrFilters[] = $attr . '=' . $word;
+            }
+            $wordFilters[] = $this->combineFilterWithOr($wordMatchOneAttrFilters);
+        }
+        return $this->combineFilterWithAnd($wordFilters);
+    }
+
+    /**
+     * creates a filter part for searches
+     *
+     * @param string $search the search term
+     * @param string[]|null|'' $searchAttributes
+     * @param string $fallbackAttribute a fallback attribute in case the user
+     * did not define search attributes. Typically the display name attribute.
+     * @return string the final filter part to use in LDAP searches
+     */
+    private function getFilterPartForSearch(string $search, $searchAttributes, string $fallbackAttribute): string {
+        $filter = [];
+        $haveMultiSearchAttributes = (is_array($searchAttributes) && count($searchAttributes) > 0);
+        if ($haveMultiSearchAttributes && strpos(trim($search), ' ') !== false) {
+            try {
+                return $this->getAdvancedFilterPartForSearch($search, $searchAttributes);
+            } catch (DomainException $e) {
+                // Creating advanced filter for search failed, falling back to simple method. Edge case, but valid.
+            }
+        }
+
+        $originalSearch = $search;
+        $search = $this->prepareSearchTerm($search);
+        if (!is_array($searchAttributes) || count($searchAttributes) === 0) {
+            if ($fallbackAttribute === '') {
+                return '';
+            }
+            // wildcards don't work with some attributes
+            $filter[] = $fallbackAttribute . '=' . $originalSearch;
+            $filter[] = $fallbackAttribute . '=' . $search;
+        } else {
+            foreach ($searchAttributes as $attribute) {
+                // wildcards don't work with some attributes
+                $filter[] = $attribute . '=' . $originalSearch;
+                $filter[] = $attribute . '=' . $search;
+            }
+        }
+        if (count($filter) === 1) {
+            return '(' . $filter[0] . ')';
+        }
+        return $this->combineFilterWithOr($filter);
+    }
+
+    /**
+     * returns the search term depending on whether we are allowed
+     * list users found by ldap with the current input appended by
+     * a *
+     */
+    private function prepareSearchTerm(string $term): string {
+        $config = \OC::$server->getConfig();
+
+        $allowEnum = $config->getAppValue('core', 'shareapi_allow_share_dialog_user_enumeration', 'yes');
+
+        $result = $term;
+        if ($term === '') {
+            $result = '*';
+        } elseif ($allowEnum !== 'no') {
+            $result = $term . '*';
+        }
+        return $result;
+    }
+
+    /**
+     * returns the filter used for counting users
+     */
+    public function getFilterForUserCount(): string {
+        $filter = $this->combineFilterWithAnd([
+            $this->connection->ldapUserFilter,
+            $this->connection->ldapUserDisplayName . '=*'
+        ]);
+
+        return $filter;
+    }
+
+    /**
+     * @param string $name
+     * @param string $password
+     * @return bool
+     */
+    public function areCredentialsValid($name, $password) {
+        $name = $this->helper->DNasBaseParameter($name);
+        $testConnection = clone $this->connection;
+        $credentials = [
+            'ldapAgentName' => $name,
+            'ldapAgentPassword' => $password
+        ];
+        if (!$testConnection->setConfiguration($credentials)) {
+            return false;
+        }
+        return $testConnection->bind();
+    }
+
+    /**
+     * reverse lookup of a DN given a known UUID
+     *
+     * @param string $uuid
+     * @return string
+     * @throws \Exception
+     */
+    public function getUserDnByUuid($uuid) {
+        $uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
+        $filter = $this->connection->ldapUserFilter;
+        $bases = $this->connection->ldapBaseUsers;
+
+        if ($this->connection->ldapUuidUserAttribute === 'auto' && $uuidOverride === '') {
+            // Sacrebleu! The UUID attribute is unknown :( We need first an
+            // existing DN to be able to reliably detect it.
+            foreach ($bases as $base) {
+                $result = $this->search($filter, $base, ['dn'], 1);
+                if (!isset($result[0]) || !isset($result[0]['dn'])) {
+                    continue;
+                }
+                $dn = $result[0]['dn'][0];
+                if ($hasFound = $this->detectUuidAttribute($dn, true)) {
+                    break;
+                }
+            }
+            if (!isset($hasFound) || !$hasFound) {
+                throw new \Exception('Cannot determine UUID attribute');
+            }
+        } else {
+            // The UUID attribute is either known or an override is given.
+            // By calling this method we ensure that $this->connection->$uuidAttr
+            // is definitely set
+            if (!$this->detectUuidAttribute('', true)) {
+                throw new \Exception('Cannot determine UUID attribute');
+            }
+        }
+
+        $uuidAttr = $this->connection->ldapUuidUserAttribute;
+        if ($uuidAttr === 'guid' || $uuidAttr === 'objectguid') {
+            $uuid = $this->formatGuid2ForFilterUser($uuid);
+        }
+
+        $filter = $uuidAttr . '=' . $uuid;
+        $result = $this->searchUsers($filter, ['dn'], 2);
+        if (isset($result[0]['dn']) && count($result) === 1) {
+            // we put the count into account to make sure that this is
+            // really unique
+            return $result[0]['dn'][0];
+        }
+
+        throw new \Exception('Cannot determine UUID attribute');
+    }
+
+    /**
+     * auto-detects the directory's UUID attribute
+     *
+     * @param string $dn a known DN used to check against
+     * @param bool $isUser
+     * @param bool $force the detection should be run, even if it is not set to auto
+     * @param array|null $ldapRecord
+     * @return bool true on success, false otherwise
+     * @throws ServerNotAvailableException
+     */
+    private function detectUuidAttribute(string $dn, bool $isUser = true, bool $force = false, ?array $ldapRecord = null): bool {
+        if ($isUser) {
+            $uuidAttr = 'ldapUuidUserAttribute';
+            $uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
+        } else {
+            $uuidAttr = 'ldapUuidGroupAttribute';
+            $uuidOverride = $this->connection->ldapExpertUUIDGroupAttr;
+        }
+
+        if (!$force) {
+            if ($this->connection->$uuidAttr !== 'auto') {
+                return true;
+            } elseif (is_string($uuidOverride) && trim($uuidOverride) !== '') {
+                $this->connection->$uuidAttr = $uuidOverride;
+                return true;
+            }
+
+            $attribute = $this->connection->getFromCache($uuidAttr);
+            if ($attribute !== null) {
+                $this->connection->$uuidAttr = $attribute;
+                return true;
+            }
+        }
+
+        foreach (self::UUID_ATTRIBUTES as $attribute) {
+            if ($ldapRecord !== null) {
+                // we have the info from LDAP already, we don't need to talk to the server again
+                if (isset($ldapRecord[$attribute])) {
+                    $this->connection->$uuidAttr = $attribute;
+                    return true;
+                }
+            }
+
+            $value = $this->readAttribute($dn, $attribute);
+            if (is_array($value) && isset($value[0]) && !empty($value[0])) {
+                $this->logger->debug(
+                    'Setting {attribute} as {subject}',
+                    [
+                        'app' => 'user_ldap',
+                        'attribute' => $attribute,
+                        'subject' => $uuidAttr
+                    ]
+                );
+                $this->connection->$uuidAttr = $attribute;
+                $this->connection->writeToCache($uuidAttr, $attribute);
+                return true;
+            }
+        }
+        $this->logger->debug('Could not autodetect the UUID attribute', ['app' => 'user_ldap']);
+
+        return false;
+    }
+
+    /**
+     * @param array|null $ldapRecord
+     * @return false|string
+     * @throws ServerNotAvailableException
+     */
+    public function getUUID(string $dn, bool $isUser = true, array $ldapRecord = null) {
+        if ($isUser) {
+            $uuidAttr = 'ldapUuidUserAttribute';
+            $uuidOverride = $this->connection->ldapExpertUUIDUserAttr;
+        } else {
+            $uuidAttr = 'ldapUuidGroupAttribute';
+            $uuidOverride = $this->connection->ldapExpertUUIDGroupAttr;
+        }
+
+        $uuid = false;
+        if ($this->detectUuidAttribute($dn, $isUser, false, $ldapRecord)) {
+            $attr = $this->connection->$uuidAttr;
+            $uuid = isset($ldapRecord[$attr]) ? $ldapRecord[$attr] : $this->readAttribute($dn, $attr);
+            if (!is_array($uuid)
+                && $uuidOverride !== ''
+                && $this->detectUuidAttribute($dn, $isUser, true, $ldapRecord)) {
+                $uuid = isset($ldapRecord[$this->connection->$uuidAttr])
+                    ? $ldapRecord[$this->connection->$uuidAttr]
+                    : $this->readAttribute($dn, $this->connection->$uuidAttr);
+            }
+            if (is_array($uuid) && !empty($uuid[0])) {
+                $uuid = $uuid[0];
+            }
+        }
+
+        return $uuid;
+    }
+
+    /**
+     * converts a binary ObjectGUID into a string representation
+     *
+     * @param string $oguid the ObjectGUID in its binary form as retrieved from AD
+     * @link https://www.php.net/manual/en/function.ldap-get-values-len.php#73198
+     */
+    private function convertObjectGUID2Str(string $oguid): string {
+        $hex_guid = bin2hex($oguid);
+        $hex_guid_to_guid_str = '';
+        for ($k = 1; $k <= 4; ++$k) {
+            $hex_guid_to_guid_str .= substr($hex_guid, 8 - 2 * $k, 2);
+        }
+        $hex_guid_to_guid_str .= '-';
+        for ($k = 1; $k <= 2; ++$k) {
+            $hex_guid_to_guid_str .= substr($hex_guid, 12 - 2 * $k, 2);
+        }
+        $hex_guid_to_guid_str .= '-';
+        for ($k = 1; $k <= 2; ++$k) {
+            $hex_guid_to_guid_str .= substr($hex_guid, 16 - 2 * $k, 2);
+        }
+        $hex_guid_to_guid_str .= '-' . substr($hex_guid, 16, 4);
+        $hex_guid_to_guid_str .= '-' . substr($hex_guid, 20);
+
+        return strtoupper($hex_guid_to_guid_str);
+    }
+
+    /**
+     * the first three blocks of the string-converted GUID happen to be in
+     * reverse order. In order to use it in a filter, this needs to be
+     * corrected. Furthermore the dashes need to be replaced and \\ prepended
+     * to every two hex figures.
+     *
+     * If an invalid string is passed, it will be returned without change.
+     */
+    public function formatGuid2ForFilterUser(string $guid): string {
+        $blocks = explode('-', $guid);
+        if (count($blocks) !== 5) {
+            /*
 			 * Why not throw an Exception instead? This method is a utility
 			 * called only when trying to figure out whether a "missing" known
 			 * LDAP user was or was not renamed on the LDAP server. And this
@@ -1805,237 +1805,237 @@ 
 			 * an exception here would kill the experience for a valid, acting
 			 * user. Instead we write a log message.
 			 */
-			$this->logger->info(
-				'Passed string does not resemble a valid GUID. Known UUID ' .
-				'({uuid}) probably does not match UUID configuration.',
-				['app' => 'user_ldap', 'uuid' => $guid]
-			);
-			return $guid;
-		}
-		for ($i = 0; $i < 3; $i++) {
-			$pairs = str_split($blocks[$i], 2);
-			$pairs = array_reverse($pairs);
-			$blocks[$i] = implode('', $pairs);
-		}
-		for ($i = 0; $i < 5; $i++) {
-			$pairs = str_split($blocks[$i], 2);
-			$blocks[$i] = '\\' . implode('\\', $pairs);
-		}
-		return implode('', $blocks);
-	}
-
-	/**
-	 * gets a SID of the domain of the given dn
-	 *
-	 * @param string $dn
-	 * @return string|bool
-	 * @throws ServerNotAvailableException
-	 */
-	public function getSID($dn) {
-		$domainDN = $this->getDomainDNFromDN($dn);
-		$cacheKey = 'getSID-' . $domainDN;
-		$sid = $this->connection->getFromCache($cacheKey);
-		if (!is_null($sid)) {
-			return $sid;
-		}
-
-		$objectSid = $this->readAttribute($domainDN, 'objectsid');
-		if (!is_array($objectSid) || empty($objectSid)) {
-			$this->connection->writeToCache($cacheKey, false);
-			return false;
-		}
-		$domainObjectSid = $this->convertSID2Str($objectSid[0]);
-		$this->connection->writeToCache($cacheKey, $domainObjectSid);
-
-		return $domainObjectSid;
-	}
-
-	/**
-	 * converts a binary SID into a string representation
-	 *
-	 * @param string $sid
-	 * @return string
-	 */
-	public function convertSID2Str($sid) {
-		// The format of a SID binary string is as follows:
-		// 1 byte for the revision level
-		// 1 byte for the number n of variable sub-ids
-		// 6 bytes for identifier authority value
-		// n*4 bytes for n sub-ids
-		//
-		// Example: 010400000000000515000000a681e50e4d6c6c2bca32055f
-		//  Legend: RRNNAAAAAAAAAAAA11111111222222223333333344444444
-		$revision = ord($sid[0]);
-		$numberSubID = ord($sid[1]);
-
-		$subIdStart = 8; // 1 + 1 + 6
-		$subIdLength = 4;
-		if (strlen($sid) !== $subIdStart + $subIdLength * $numberSubID) {
-			// Incorrect number of bytes present.
-			return '';
-		}
-
-		// 6 bytes = 48 bits can be represented using floats without loss of
-		// precision (see https://gist.github.com/bantu/886ac680b0aef5812f71)
-		$iav = number_format(hexdec(bin2hex(substr($sid, 2, 6))), 0, '', '');
-
-		$subIDs = [];
-		for ($i = 0; $i < $numberSubID; $i++) {
-			$subID = unpack('V', substr($sid, $subIdStart + $subIdLength * $i, $subIdLength));
-			$subIDs[] = sprintf('%u', $subID[1]);
-		}
-
-		// Result for example above: S-1-5-21-249921958-728525901-1594176202
-		return sprintf('S-%d-%s-%s', $revision, $iav, implode('-', $subIDs));
-	}
-
-	/**
-	 * checks if the given DN is part of the given base DN(s)
-	 *
-	 * @param string[] $bases array containing the allowed base DN or DNs
-	 */
-	public function isDNPartOfBase(string $dn, array $bases): bool {
-		$belongsToBase = false;
-		$bases = $this->helper->sanitizeDN($bases);
-
-		foreach ($bases as $base) {
-			$belongsToBase = true;
-			if (mb_strripos($dn, $base, 0, 'UTF-8') !== (mb_strlen($dn, 'UTF-8') - mb_strlen($base, 'UTF-8'))) {
-				$belongsToBase = false;
-			}
-			if ($belongsToBase) {
-				break;
-			}
-		}
-		return $belongsToBase;
-	}
-
-	/**
-	 * resets a running Paged Search operation
-	 *
-	 * @throws ServerNotAvailableException
-	 */
-	private function abandonPagedSearch(): void {
-		if ($this->lastCookie === '') {
-			return;
-		}
-		$this->getPagedSearchResultState();
-		$this->lastCookie = '';
-	}
-
-	/**
-	 * checks whether an LDAP paged search operation has more pages that can be
-	 * retrieved, typically when offset and limit are provided.
-	 *
-	 * Be very careful to use it: the last cookie value, which is inspected, can
-	 * be reset by other operations. Best, call it immediately after a search(),
-	 * searchUsers() or searchGroups() call. count-methods are probably safe as
-	 * well. Don't rely on it with any fetchList-method.
-	 *
-	 * @return bool
-	 */
-	public function hasMoreResults() {
-		if ($this->lastCookie === '') {
-			// as in RFC 2696, when all results are returned, the cookie will
-			// be empty.
-			return false;
-		}
-
-		return true;
-	}
-
-	/**
-	 * Check whether the most recent paged search was successful. It flushed the state var. Use it always after a possible paged search.
-	 *
-	 * @return boolean|null true on success, null or false otherwise
-	 */
-	public function getPagedSearchResultState() {
-		$result = $this->pagedSearchedSuccessful;
-		$this->pagedSearchedSuccessful = null;
-		return $result;
-	}
-
-	/**
-	 * Prepares a paged search, if possible
-	 *
-	 * @param string $filter the LDAP filter for the search
-	 * @param string $base the LDAP subtree that shall be searched
-	 * @param string[] $attr optional, when a certain attribute shall be filtered outside
-	 * @param int $limit
-	 * @param int $offset
-	 * @return array{bool, int, string}
-	 * @throws ServerNotAvailableException
-	 * @throws NoMoreResults
-	 */
-	private function initPagedSearch(
-		string $filter,
-		string $base,
-		?array $attr,
-		int $pageSize,
-		int $offset
-	): array {
-		$pagedSearchOK = false;
-		if ($pageSize !== 0) {
-			$this->logger->debug(
-				'initializing paged search for filter {filter}, base {base}, attr {attr}, pageSize {pageSize}, offset {offset}',
-				[
-					'app' => 'user_ldap',
-					'filter' => $filter,
-					'base' => $base,
-					'attr' => $attr,
-					'pageSize' => $pageSize,
-					'offset' => $offset
-				]
-			);
-			// Get the cookie from the search for the previous search, required by LDAP
-			if (($this->lastCookie === '') && ($offset > 0)) {
-				// no cookie known from a potential previous search. We need
-				// to start from 0 to come to the desired page. cookie value
-				// of '0' is valid, because 389ds
-				$reOffset = ($offset - $pageSize) < 0 ? 0 : $offset - $pageSize;
-				$this->search($filter, $base, $attr, $pageSize, $reOffset, true);
-				if (!$this->hasMoreResults()) {
-					// when the cookie is reset with != 0 offset, there are no further
-					// results, so stop.
-					throw new NoMoreResults();
-				}
-			}
-			if ($this->lastCookie !== '' && $offset === 0) {
-				//since offset = 0, this is a new search. We abandon other searches that might be ongoing.
-				$this->abandonPagedSearch();
-			}
-			$this->logger->debug('Ready for a paged search', ['app' => 'user_ldap']);
-			return [true, $pageSize, $this->lastCookie];
-			/* ++ Fixing RHDS searches with pages with zero results ++
+            $this->logger->info(
+                'Passed string does not resemble a valid GUID. Known UUID ' .
+                '({uuid}) probably does not match UUID configuration.',
+                ['app' => 'user_ldap', 'uuid' => $guid]
+            );
+            return $guid;
+        }
+        for ($i = 0; $i < 3; $i++) {
+            $pairs = str_split($blocks[$i], 2);
+            $pairs = array_reverse($pairs);
+            $blocks[$i] = implode('', $pairs);
+        }
+        for ($i = 0; $i < 5; $i++) {
+            $pairs = str_split($blocks[$i], 2);
+            $blocks[$i] = '\\' . implode('\\', $pairs);
+        }
+        return implode('', $blocks);
+    }
+
+    /**
+     * gets a SID of the domain of the given dn
+     *
+     * @param string $dn
+     * @return string|bool
+     * @throws ServerNotAvailableException
+     */
+    public function getSID($dn) {
+        $domainDN = $this->getDomainDNFromDN($dn);
+        $cacheKey = 'getSID-' . $domainDN;
+        $sid = $this->connection->getFromCache($cacheKey);
+        if (!is_null($sid)) {
+            return $sid;
+        }
+
+        $objectSid = $this->readAttribute($domainDN, 'objectsid');
+        if (!is_array($objectSid) || empty($objectSid)) {
+            $this->connection->writeToCache($cacheKey, false);
+            return false;
+        }
+        $domainObjectSid = $this->convertSID2Str($objectSid[0]);
+        $this->connection->writeToCache($cacheKey, $domainObjectSid);
+
+        return $domainObjectSid;
+    }
+
+    /**
+     * converts a binary SID into a string representation
+     *
+     * @param string $sid
+     * @return string
+     */
+    public function convertSID2Str($sid) {
+        // The format of a SID binary string is as follows:
+        // 1 byte for the revision level
+        // 1 byte for the number n of variable sub-ids
+        // 6 bytes for identifier authority value
+        // n*4 bytes for n sub-ids
+        //
+        // Example: 010400000000000515000000a681e50e4d6c6c2bca32055f
+        //  Legend: RRNNAAAAAAAAAAAA11111111222222223333333344444444
+        $revision = ord($sid[0]);
+        $numberSubID = ord($sid[1]);
+
+        $subIdStart = 8; // 1 + 1 + 6
+        $subIdLength = 4;
+        if (strlen($sid) !== $subIdStart + $subIdLength * $numberSubID) {
+            // Incorrect number of bytes present.
+            return '';
+        }
+
+        // 6 bytes = 48 bits can be represented using floats without loss of
+        // precision (see https://gist.github.com/bantu/886ac680b0aef5812f71)
+        $iav = number_format(hexdec(bin2hex(substr($sid, 2, 6))), 0, '', '');
+
+        $subIDs = [];
+        for ($i = 0; $i < $numberSubID; $i++) {
+            $subID = unpack('V', substr($sid, $subIdStart + $subIdLength * $i, $subIdLength));
+            $subIDs[] = sprintf('%u', $subID[1]);
+        }
+
+        // Result for example above: S-1-5-21-249921958-728525901-1594176202
+        return sprintf('S-%d-%s-%s', $revision, $iav, implode('-', $subIDs));
+    }
+
+    /**
+     * checks if the given DN is part of the given base DN(s)
+     *
+     * @param string[] $bases array containing the allowed base DN or DNs
+     */
+    public function isDNPartOfBase(string $dn, array $bases): bool {
+        $belongsToBase = false;
+        $bases = $this->helper->sanitizeDN($bases);
+
+        foreach ($bases as $base) {
+            $belongsToBase = true;
+            if (mb_strripos($dn, $base, 0, 'UTF-8') !== (mb_strlen($dn, 'UTF-8') - mb_strlen($base, 'UTF-8'))) {
+                $belongsToBase = false;
+            }
+            if ($belongsToBase) {
+                break;
+            }
+        }
+        return $belongsToBase;
+    }
+
+    /**
+     * resets a running Paged Search operation
+     *
+     * @throws ServerNotAvailableException
+     */
+    private function abandonPagedSearch(): void {
+        if ($this->lastCookie === '') {
+            return;
+        }
+        $this->getPagedSearchResultState();
+        $this->lastCookie = '';
+    }
+
+    /**
+     * checks whether an LDAP paged search operation has more pages that can be
+     * retrieved, typically when offset and limit are provided.
+     *
+     * Be very careful to use it: the last cookie value, which is inspected, can
+     * be reset by other operations. Best, call it immediately after a search(),
+     * searchUsers() or searchGroups() call. count-methods are probably safe as
+     * well. Don't rely on it with any fetchList-method.
+     *
+     * @return bool
+     */
+    public function hasMoreResults() {
+        if ($this->lastCookie === '') {
+            // as in RFC 2696, when all results are returned, the cookie will
+            // be empty.
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Check whether the most recent paged search was successful. It flushed the state var. Use it always after a possible paged search.
+     *
+     * @return boolean|null true on success, null or false otherwise
+     */
+    public function getPagedSearchResultState() {
+        $result = $this->pagedSearchedSuccessful;
+        $this->pagedSearchedSuccessful = null;
+        return $result;
+    }
+
+    /**
+     * Prepares a paged search, if possible
+     *
+     * @param string $filter the LDAP filter for the search
+     * @param string $base the LDAP subtree that shall be searched
+     * @param string[] $attr optional, when a certain attribute shall be filtered outside
+     * @param int $limit
+     * @param int $offset
+     * @return array{bool, int, string}
+     * @throws ServerNotAvailableException
+     * @throws NoMoreResults
+     */
+    private function initPagedSearch(
+        string $filter,
+        string $base,
+        ?array $attr,
+        int $pageSize,
+        int $offset
+    ): array {
+        $pagedSearchOK = false;
+        if ($pageSize !== 0) {
+            $this->logger->debug(
+                'initializing paged search for filter {filter}, base {base}, attr {attr}, pageSize {pageSize}, offset {offset}',
+                [
+                    'app' => 'user_ldap',
+                    'filter' => $filter,
+                    'base' => $base,
+                    'attr' => $attr,
+                    'pageSize' => $pageSize,
+                    'offset' => $offset
+                ]
+            );
+            // Get the cookie from the search for the previous search, required by LDAP
+            if (($this->lastCookie === '') && ($offset > 0)) {
+                // no cookie known from a potential previous search. We need
+                // to start from 0 to come to the desired page. cookie value
+                // of '0' is valid, because 389ds
+                $reOffset = ($offset - $pageSize) < 0 ? 0 : $offset - $pageSize;
+                $this->search($filter, $base, $attr, $pageSize, $reOffset, true);
+                if (!$this->hasMoreResults()) {
+                    // when the cookie is reset with != 0 offset, there are no further
+                    // results, so stop.
+                    throw new NoMoreResults();
+                }
+            }
+            if ($this->lastCookie !== '' && $offset === 0) {
+                //since offset = 0, this is a new search. We abandon other searches that might be ongoing.
+                $this->abandonPagedSearch();
+            }
+            $this->logger->debug('Ready for a paged search', ['app' => 'user_ldap']);
+            return [true, $pageSize, $this->lastCookie];
+            /* ++ Fixing RHDS searches with pages with zero results ++
 			 * We couldn't get paged searches working with our RHDS for login ($limit = 0),
 			 * due to pages with zero results.
 			 * So we added "&& !empty($this->lastCookie)" to this test to ignore pagination
 			 * if we don't have a previous paged search.
 			 */
-		} elseif ($this->lastCookie !== '') {
-			// a search without limit was requested. However, if we do use
-			// Paged Search once, we always must do it. This requires us to
-			// initialize it with the configured page size.
-			$this->abandonPagedSearch();
-			// in case someone set it to 0 … use 500, otherwise no results will
-			// be returned.
-			$pageSize = (int)$this->connection->ldapPagingSize > 0 ? (int)$this->connection->ldapPagingSize : 500;
-			return [true, $pageSize, $this->lastCookie];
-		}
-
-		return [false, $pageSize, ''];
-	}
-
-	/**
-	 * Is more than one $attr used for search?
-	 *
-	 * @param string|string[]|null $attr
-	 * @return bool
-	 */
-	private function manyAttributes($attr): bool {
-		if (\is_array($attr)) {
-			return \count($attr) > 1;
-		}
-		return false;
-	}
+        } elseif ($this->lastCookie !== '') {
+            // a search without limit was requested. However, if we do use
+            // Paged Search once, we always must do it. This requires us to
+            // initialize it with the configured page size.
+            $this->abandonPagedSearch();
+            // in case someone set it to 0 … use 500, otherwise no results will
+            // be returned.
+            $pageSize = (int)$this->connection->ldapPagingSize > 0 ? (int)$this->connection->ldapPagingSize : 500;
+            return [true, $pageSize, $this->lastCookie];
+        }
+
+        return [false, $pageSize, ''];
+    }
+
+    /**
+     * Is more than one $attr used for search?
+     *
+     * @param string|string[]|null $attr
+     * @return bool
+     */
+    private function manyAttributes($attr): bool {
+        if (\is_array($attr)) {
+            return \count($attr) > 1;
+        }
+        return false;
+    }
 }