From 464663877ca44084b246c034381b5cc9a8a99e3b Mon Sep 17 00:00:00 2001
From: Michael Kaufmann <d00p@froxlor.org>
Date: Tue, 7 Feb 2023 11:15:19 +0100
Subject: [PATCH] cleanup function/parameters and add type declarations where
 possible

Signed-off-by: Michael Kaufmann <d00p@froxlor.org>
---
 lib/Froxlor/CurrentUser.php                   |  19 +-
 lib/Froxlor/Customer/Customer.php             |  36 ++--
 lib/Froxlor/Database/Database.php             |  79 ++++----
 lib/Froxlor/Database/DbManager.php            |  17 +-
 lib/Froxlor/Database/IntegrityCheck.php       | 109 ++++++-----
 .../Database/Manager/DbManagerMySQL.php       |  32 +--
 lib/Froxlor/Dns/Dns.php                       | 104 +++++++---
 lib/Froxlor/Dns/DnsEntry.php                  |  25 ++-
 lib/Froxlor/Dns/DnsZone.php                   |  24 ++-
 lib/Froxlor/Dns/PowerDNS.php                  |  13 +-
 lib/Froxlor/Domain/Domain.php                 | 134 +++++++------
 lib/Froxlor/Domain/IpAddr.php                 |  18 +-
 lib/Froxlor/FileDir.php                       | 144 ++++++--------
 lib/Froxlor/Froxlor.php                       |  87 +++++----
 lib/Froxlor/FroxlorLogger.php                 |  43 ++--
 lib/Froxlor/Http/Directory.php                |  19 +-
 lib/Froxlor/Http/HttpClient.php               |   8 +
 lib/Froxlor/Http/PhpConfig.php                |   2 +-
 lib/Froxlor/Http/Statistics.php               |  35 ++--
 lib/Froxlor/Idna/IdnaWrapper.php              |  16 +-
 lib/Froxlor/PhpHelper.php                     | 183 +++++++++---------
 lib/Froxlor/Settings/FroxlorVhostSettings.php |  13 +-
 lib/Froxlor/System/Cronjob.php                |  46 +++--
 lib/Froxlor/System/Crypt.php                  |  67 ++++---
 lib/Froxlor/System/IPTools.php                |  31 +--
 lib/Froxlor/System/Mailer.php                 |   5 +-
 lib/Froxlor/System/MysqlHandler.php           |  13 +-
 lib/Froxlor/Traffic/Traffic.php               |  35 ++--
 lib/Froxlor/Validate/Check.php                |  61 +++++-
 lib/Froxlor/Validate/Form.php                 |  40 ++--
 lib/Froxlor/Validate/Validate.php             | 121 ++++++------
 31 files changed, 928 insertions(+), 651 deletions(-)

diff --git a/lib/Froxlor/CurrentUser.php b/lib/Froxlor/CurrentUser.php
index af635727..22a62082 100644
--- a/lib/Froxlor/CurrentUser.php
+++ b/lib/Froxlor/CurrentUser.php
@@ -63,9 +63,10 @@ class CurrentUser
 	/**
 	 * re-read in the user data if a valid session exists
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function reReadUserData()
+	public static function reReadUserData(): bool
 	{
 		$table = self::isAdmin() ? TABLE_PANEL_ADMINS : TABLE_PANEL_CUSTOMERS;
 		$userinfo_stmt = Database::prepare("
@@ -75,7 +76,7 @@ class CurrentUser
 			"loginname" => self::getField('loginname')
 		]);
 		if ($userinfo) {
-			// dont just set the data, we need to merge with current data
+			// don't just set the data, we need to merge with current data
 			// array_merge is a right-reduction - value existing in getData() will be overwritten with $userinfo,
 			// other than the union-operator (+) which would keep the values already existing from getData()
 			$newuserinfo = array_merge(self::getData(), $userinfo);
@@ -107,7 +108,7 @@ class CurrentUser
 	 */
 	public static function getField(string $index)
 	{
-		return isset($_SESSION['userinfo'][$index]) ? $_SESSION['userinfo'][$index] : "";
+		return $_SESSION['userinfo'][$index] ?? "";
 	}
 
 	/**
@@ -130,6 +131,11 @@ class CurrentUser
 		$_SESSION['userinfo'] = $data;
 	}
 
+	/**
+	 * @param string $resource
+	 * @return bool
+	 * @throws \Exception
+	 */
 	public static function canAddResource(string $resource): bool
 	{
 		$addition = true;
@@ -145,14 +151,15 @@ class CurrentUser
 			]);
 			$addition = $result['emaildomains'] != 0;
 		} elseif ($resource == 'subdomains') {
-			$parentDomainCollection = (new Collection(SubDomains::class, $_SESSION['userinfo'], ['sql_search' => ['d.parentdomainid' => 0]]));
+			$parentDomainCollection = (new Collection(SubDomains::class, $_SESSION['userinfo'],
+				['sql_search' => ['d.parentdomainid' => 0]]));
 			$addition = $parentDomainCollection != 0;
 		} elseif ($resource == 'domains') {
 			$customerCollection = (new Collection(Customers::class, $_SESSION['userinfo']));
 			$addition = $customerCollection != 0;
 		}
 
-		return ($_SESSION['userinfo'][$resource.'_used'] < $_SESSION['userinfo'][$resource] || $_SESSION['userinfo'][$resource] == '-1') && $addition;
+		return ($_SESSION['userinfo'][$resource . '_used'] < $_SESSION['userinfo'][$resource] || $_SESSION['userinfo'][$resource] == '-1') && $addition;
 	}
 
 }
diff --git a/lib/Froxlor/Customer/Customer.php b/lib/Froxlor/Customer/Customer.php
index 7e81a348..27581d1c 100644
--- a/lib/Froxlor/Customer/Customer.php
+++ b/lib/Froxlor/Customer/Customer.php
@@ -31,7 +31,15 @@ use PDO;
 class Customer
 {
 
-	public static function getCustomerDetail($customerid, $varname)
+	/**
+	 * Get value of a a specific field from a given customer
+	 *
+	 * @param int $customerid
+	 * @param string $varname
+	 * @return false|mixed
+	 * @throws \Exception
+	 */
+	public static function getCustomerDetail(int $customerid, string $varname)
 	{
 		$customer_stmt = Database::prepare("
 			SELECT `" . $varname . "` FROM `" . TABLE_PANEL_CUSTOMERS . "` WHERE `customerid` = :customerid
@@ -42,20 +50,19 @@ class Customer
 
 		if (isset($customer[$varname])) {
 			return $customer[$varname];
-		} else {
-			return false;
 		}
+		return false;
 	}
 
 	/**
 	 * returns the loginname of a customer by given uid
 	 *
-	 * @param int $uid
-	 *            uid of customer
+	 * @param int $uid uid of customer
 	 *
 	 * @return string customers loginname
+	 * @throws \Exception
 	 */
-	public static function getLoginNameByUid($uid = null)
+	public static function getLoginNameByUid(int $uid)
 	{
 		$result_stmt = Database::prepare("
 			SELECT `loginname` FROM `" . TABLE_PANEL_CUSTOMERS . "` WHERE `guid` = :guid
@@ -64,7 +71,7 @@ class Customer
 			'guid' => $uid
 		]);
 
-		if (is_array($result) && isset($result['loginname'])) {
+		if ($result && isset($result['loginname'])) {
 			return $result['loginname'];
 		}
 		return false;
@@ -76,23 +83,22 @@ class Customer
 	 * returns true or false whether perl is
 	 * enabled for the given customer
 	 *
-	 * @param
-	 *            int customer-id
+	 * @param int $cid customer-id
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function customerHasPerlEnabled($cid = 0)
+	public static function customerHasPerlEnabled(int $cid = 0)
 	{
 		if ($cid > 0) {
 			$result_stmt = Database::prepare("
 				SELECT `perlenabled` FROM `" . TABLE_PANEL_CUSTOMERS . "` WHERE `customerid` = :cid");
-			Database::pexecute($result_stmt, [
+			$result = Database::pexecute_first($result_stmt, [
 				'cid' => $cid
 			]);
-			$result = $result_stmt->fetch(PDO::FETCH_ASSOC);
 
-			if (is_array($result) && isset($result['perlenabled'])) {
-				return $result['perlenabled'] == '1';
+			if ($result && isset($result['perlenabled'])) {
+				return (bool)$result['perlenabled'];
 			}
 		}
 		return false;
diff --git a/lib/Froxlor/Database/Database.php b/lib/Froxlor/Database/Database.php
index 2157e5ee..2e76b075 100644
--- a/lib/Froxlor/Database/Database.php
+++ b/lib/Froxlor/Database/Database.php
@@ -83,19 +83,21 @@ class Database
 	private static $need_dbname = true;
 
 	/**
-	 * Wrapper for PDOStatement::execute so we can catch the PDOException
+	 * Wrapper for PDOStatement::execute, so we can catch the PDOException
 	 * and display the error nicely on the panel - also fetches the
 	 * result from the statement and returns the resulting array
 	 *
 	 * @param PDOStatement $stmt
-	 * @param array $params
+	 * @param array|null $params
 	 *            (optional)
 	 * @param bool $showerror
-	 *            suppress errordisplay (default true)
+	 *            suppress error display (default true)
+	 * @param bool $json_response
 	 *
 	 * @return array
+	 * @throws Exception
 	 */
-	public static function pexecute_first(&$stmt, $params = null, $showerror = true, $json_response = false)
+	public static function pexecute_first(PDOStatement &$stmt, $params = null, bool $showerror = true, bool $json_response = false): array
 	{
 		self::pexecute($stmt, $params, $showerror, $json_response);
 		return $stmt->fetch(PDO::FETCH_ASSOC);
@@ -106,12 +108,15 @@ class Database
 	 * and display the error nicely on the panel
 	 *
 	 * @param PDOStatement $stmt
-	 * @param array $params
+	 * @param array|null $params
 	 *            (optional)
 	 * @param bool $showerror
-	 *            suppress errordisplay (default true)
+	 *            suppress error display (default true)
+	 * @param bool $json_response
+	 *
+	 * @throws Exception
 	 */
-	public static function pexecute(&$stmt, $params = null, $showerror = true, $json_response = false)
+	public static function pexecute(PDOStatement &$stmt, $params = null, bool $showerror = true, bool $json_response = false)
 	{
 		try {
 			$stmt->execute($params);
@@ -125,9 +130,10 @@ class Database
 	 *
 	 * @param PDOException $error
 	 * @param bool $showerror
-	 *            if set to false, the error will be logged but we go on
+	 *            if set to false, the error will be logged, but we go on
+	 * @throws Exception
 	 */
-	private static function showerror($error, $showerror = true, $json_response = false, PDOStatement $stmt = null)
+	private static function showerror(Exception $error, bool $showerror = true, bool $json_response = false, PDOStatement $stmt = null)
 	{
 		global $userinfo, $theme, $linker;
 
@@ -143,7 +149,7 @@ class Database
 				0 => [
 					'caption' => 'Default',
 					'host' => $sql['host'],
-					'socket' => (isset($sql['socket']) ? $sql['socket'] : null),
+					'socket' => ($sql['socket'] ?? null),
 					'user' => $sql['root_user'],
 					'password' => $sql['root_password']
 				]
@@ -159,8 +165,8 @@ class Database
 		$substitutions = [
 			$sql['password'] => 'DB_UNPRIV_PWD',
 		];
-		foreach ($sql_root as $dbserver => $sql_root_data) {
-			$substitutions[$sql_root_data[$dbserver]]['password'] = 'DB_ROOT_PWD';
+		foreach ($sql_root as $sql_root_data) {
+			$substitutions[$sql_root_data['password']] = 'DB_ROOT_PWD';
 		}
 
 		// hide username/password in messages
@@ -254,7 +260,7 @@ class Database
 	 * @param int $minLength
 	 * @return string
 	 */
-	private static function substitute($content, array $substitutions, $minLength = 6)
+	private static function substitute(string $content, array $substitutions, int $minLength = 6): string
 	{
 		$replacements = [];
 
@@ -262,9 +268,7 @@ class Database
 			$replacements += self::createShiftedSubstitutions($search, $replace, $minLength);
 		}
 
-		$content = str_replace(array_keys($replacements), array_values($replacements), $content);
-
-		return $content;
+		return str_replace(array_keys($replacements), array_values($replacements), $content);
 	}
 
 	/**
@@ -284,7 +288,7 @@ class Database
 	 * @param int $minLength
 	 * @return array
 	 */
-	private static function createShiftedSubstitutions($search, $replace, $minLength)
+	private static function createShiftedSubstitutions(string $search, string $replace, int $minLength): array
 	{
 		$substitutions = [];
 		$length = strlen($search);
@@ -303,8 +307,9 @@ class Database
 	 *
 	 * @param int $length
 	 * @return string
+	 * @throws Exception
 	 */
-	private static function genUniqueToken(int $length = 16)
+	private static function genUniqueToken(int $length = 16): string
 	{
 		if (intval($length) <= 8) {
 			$length = 16;
@@ -327,7 +332,7 @@ class Database
 	 *
 	 * @return int
 	 */
-	public static function num_rows()
+	public static function num_rows(): int
 	{
 		return Database::query("SELECT FOUND_ROWS()")->fetchColumn();
 	}
@@ -337,7 +342,7 @@ class Database
 	 *
 	 * @return string
 	 */
-	public static function getDbName()
+	public static function getDbName(): ?string
 	{
 		return self::$dbname;
 	}
@@ -349,8 +354,8 @@ class Database
 	 * the 'normal' database-connection
 	 *
 	 * @param bool $needroot
-	 * @param int $dbserver
-	 *            optional
+	 * @param int $dbserver optional
+	 * @param bool $need_db
 	 */
 	public static function needRoot(bool $needroot = false, int $dbserver = 0, bool $need_db = true)
 	{
@@ -366,7 +371,7 @@ class Database
 	 *
 	 * @param int $dbserver
 	 */
-	private static function setServer($dbserver = 0)
+	private static function setServer(int $dbserver = 0)
 	{
 		self::$dbserver = $dbserver;
 		self::$link = null;
@@ -397,17 +402,16 @@ class Database
 	 * function that will be called on every static call
 	 * which connects to the database if necessary
 	 *
-	 * @param bool $root
-	 *
 	 * @return object
+	 * @throws Exception
 	 */
 	private static function getDB()
 	{
-		if (!extension_loaded('pdo') || in_array("mysql", PDO::getAvailableDrivers()) == false) {
+		if (!extension_loaded('pdo') || !in_array("mysql", PDO::getAvailableDrivers())) {
 			self::showerror(new Exception("The php PDO extension or PDO-MySQL driver is not available"));
 		}
 
-		// do we got a connection already?
+		// do we have a connection already?
 		if (self::$link) {
 			// return it
 			return self::$link;
@@ -422,7 +426,7 @@ class Database
 				0 => [
 					'caption' => 'Default',
 					'host' => $sql['host'],
-					'socket' => (isset($sql['socket']) ? $sql['socket'] : null),
+					'socket' => ($sql['socket'] ?? null),
 					'user' => $sql['root_user'],
 					'password' => $sql['root_password']
 				]
@@ -441,8 +445,8 @@ class Database
 			$user = $sql_root[self::$dbserver]['user'];
 			$password = $sql_root[self::$dbserver]['password'];
 			$host = $sql_root[self::$dbserver]['host'];
-			$socket = isset($sql_root[self::$dbserver]['socket']) ? $sql_root[self::$dbserver]['socket'] : null;
-			$port = isset($sql_root[self::$dbserver]['port']) ? $sql_root[self::$dbserver]['port'] : '3306';
+			$socket = $sql_root[self::$dbserver]['socket'] ?? null;
+			$port = $sql_root[self::$dbserver]['port'] ?? '3306';
 			$sslCAFile = $sql_root[self::$dbserver]['ssl']['caFile'] ?? "";
 			$sslVerifyServerCertificate = $sql_root[self::$dbserver]['ssl']['verifyServerCertificate'] ?? false;
 		} else {
@@ -450,8 +454,8 @@ class Database
 			$user = $sql["user"];
 			$password = $sql["password"];
 			$host = $sql["host"];
-			$socket = isset($sql['socket']) ? $sql['socket'] : null;
-			$port = isset($sql['port']) ? $sql['port'] : '3306';
+			$socket = $sql['socket'] ?? null;
+			$port = $sql['port'] ?? '3306';
 			$sslCAFile = $sql['ssl']['caFile'] ?? "";
 			$sslVerifyServerCertificate = $sql['ssl']['verifyServerCertificate'] ?? false;
 		}
@@ -556,14 +560,14 @@ class Database
 	 *
 	 * @return int
 	 */
-	public static function getSqlUsernameLength()
+	public static function getSqlUsernameLength(): int
 	{
-		// MariaDB supports up to 80 characters but only 64 for databases and as we use the loginname also for
+		// MariaDB supports up to 80 characters but only 64 for databases and as we use the login-name also for
 		// database names, we set the limit to 64 here
 		if (strpos(strtolower(Database::getAttribute(\PDO::ATTR_SERVER_VERSION)), "mariadb") !== false) {
 			$mysql_max = 64;
 		} else {
-			// MySQL user names can be up to 32 characters long (16 characters before MySQL 5.7.8).
+			// MySQL user-names can be up to 32 characters long (16 characters before MySQL 5.7.8).
 			$mysql_max = 32;
 			if (version_compare(Database::getAttribute(\PDO::ATTR_SERVER_VERSION), '5.7.8', '<')) {
 				$mysql_max = 16;
@@ -573,15 +577,16 @@ class Database
 	}
 
 	/**
-	 * let's us interact with the PDO-Object by using static
+	 * Lets us interact with the PDO-Object by using static
 	 * call like "Database::function()"
 	 *
 	 * @param string $name
 	 * @param mixed $args
 	 *
 	 * @return mixed
+	 * @throws Exception
 	 */
-	public static function __callStatic($name, $args)
+	public static function __callStatic(string $name, $args)
 	{
 		$callback = [
 			self::getDB(),
diff --git a/lib/Froxlor/Database/DbManager.php b/lib/Froxlor/Database/DbManager.php
index d57ee558..2c289a59 100644
--- a/lib/Froxlor/Database/DbManager.php
+++ b/lib/Froxlor/Database/DbManager.php
@@ -77,7 +77,15 @@ class DbManager
 		$this->manager = new DbManagerMySQL($this->log);
 	}
 
-	public static function correctMysqlUsers($mysql_access_host_array)
+	/**
+	 * function called when the mysql-access-host setting changes
+	 *
+	 * @param array $mysql_access_host_array
+	 *
+	 * @return void
+	 * @throws \Exception
+	 */
+	public static function correctMysqlUsers(array $mysql_access_host_array)
 	{
 		// get all databases for all dbservers
 		$databases = [];
@@ -136,13 +144,14 @@ class DbManager
 	 * DB-name and user-name are being generated and
 	 * the password for the user will be set
 	 *
-	 * @param string $loginname
-	 * @param string $password
+	 * @param ?string $loginname
+	 * @param ?string $password
+	 * @param int $dbserver
 	 * @param int $last_accnumber
 	 *
 	 * @return string|bool $username if successful or false of username is equal to the password
 	 */
-	public function createDatabase($loginname = null, $password = null, int $dbserver = 0, $last_accnumber = 0)
+	public function createDatabase(string $loginname = null, string $password = null, int $dbserver = 0, int $last_accnumber = 0)
 	{
 		Database::needRoot(true, $dbserver, false);
 
diff --git a/lib/Froxlor/Database/IntegrityCheck.php b/lib/Froxlor/Database/IntegrityCheck.php
index 7972f8f7..a432af15 100644
--- a/lib/Froxlor/Database/IntegrityCheck.php
+++ b/lib/Froxlor/Database/IntegrityCheck.php
@@ -85,21 +85,22 @@ class IntegrityCheck
 	/**
 	 * check whether the froxlor database and its tables are in utf-8 character-set
 	 *
-	 * @param bool $fix
-	 *            fix db charset/collation if not utf8
+	 * @param bool $fix fix db charset/collation if not utf8
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public function databaseCharset($fix = false)
+	public function databaseCharset(bool $fix = false): bool
 	{
-		// get characterset
+		// get character-set
 		$cs_stmt = Database::prepare('SELECT default_character_set_name FROM information_schema.SCHEMATA WHERE schema_name = :dbname');
 		$resp = Database::pexecute_first($cs_stmt, [
 			'dbname' => Database::getDbName()
 		]);
-		$charset = isset($resp['default_character_set_name']) ? $resp['default_character_set_name'] : null;
+		$charset = $resp['default_character_set_name'] ?? null;
 		if (!empty($charset) && substr(strtolower($charset), 0, 4) != 'utf8') {
-			$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "database charset seems to be different from UTF-8, integrity-check can fix that");
+			$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+				"database charset seems to be different from UTF-8, integrity-check can fix that");
 			if ($fix) {
 				// fix database
 				Database::query('ALTER DATABASE `' . Database::getDbName() . '` CHARACTER SET utf8 COLLATE utf8_general_ci');
@@ -109,7 +110,8 @@ class IntegrityCheck
 					$table = $row[0];
 					Database::query('ALTER TABLE `' . $table . '` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;');
 				}
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING, "database charset was different from UTF-8, integrity-check fixed that");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING,
+					"database charset was different from UTF-8, integrity-check fixed that");
 			} else {
 				return false;
 			}
@@ -124,10 +126,12 @@ class IntegrityCheck
 	/**
 	 * Check the integrity of the domain to ip/port - association
 	 *
-	 * @param bool $fix
-	 *            Fix everything found directly
+	 * @param bool $fix fix everything found directly
+	 *
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public function domainIpTable($fix = false)
+	public function domainIpTable(bool $fix = false): bool
 	{
 		$ips = [];
 		$domains = [];
@@ -184,9 +188,11 @@ class IntegrityCheck
 						'domainid' => $row['id_domain'],
 						'ipandportid' => $row['id_ipandports']
 					]);
-					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING, "found an ip/port-id in domain <> ip table which does not exist, integrity check fixed this");
+					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING,
+						"found an ip/port-id in domain <> ip table which does not exist, integrity check fixed this");
 				} else {
-					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "found an ip/port-id in domain <> ip table which does not exist, integrity check can fix this");
+					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+						"found an ip/port-id in domain <> ip table which does not exist, integrity check can fix this");
 					return false;
 				}
 			}
@@ -196,9 +202,11 @@ class IntegrityCheck
 						'domainid' => $row['id_domain'],
 						'ipandportid' => $row['id_ipandports']
 					]);
-					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING, "found a domain-id in domain <> ip table which does not exist, integrity check fixed this");
+					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING,
+						"found a domain-id in domain <> ip table which does not exist, integrity check fixed this");
 				} else {
-					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "found a domain-id in domain <> ip table which does not exist, integrity check can fix this");
+					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+						"found a domain-id in domain <> ip table which does not exist, integrity check can fix this");
 					return false;
 				}
 			}
@@ -216,9 +224,11 @@ class IntegrityCheck
 							'ipandportid' => $defaultip
 						]);
 					}
-					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING, "found a domain-id with no entry in domain <> ip table, integrity check fixed this");
+					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING,
+						"found a domain-id with no entry in domain <> ip table, integrity check fixed this");
 				} else {
-					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "found a domain-id with no entry in domain <> ip table, integrity check can fix this");
+					$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+						"found a domain-id with no entry in domain <> ip table, integrity check can fix this");
 					return false;
 				}
 			}
@@ -226,18 +236,19 @@ class IntegrityCheck
 
 		if ($fix) {
 			return $this->domainIpTable();
-		} else {
-			return true;
 		}
+		return true;
 	}
 
 	/**
 	 * Check if all subdomains have ssl-redirect = 0 if domain has no ssl-port
 	 *
-	 * @param bool $fix
-	 *            Fix everything found directly
+	 * @param bool $fix fix everything found directly
+	 *
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public function subdomainSslRedirect($fix = false)
+	public function subdomainSslRedirect(bool $fix = false): bool
 	{
 		$ips = [];
 		$parentdomains = [];
@@ -300,28 +311,31 @@ class IntegrityCheck
 				Database::pexecute($upd_stmt, [
 					'domainid' => $id
 				]);
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING, "found a subdomain with ssl_redirect=1 but parent-domain has ssl=0, integrity check fixed this");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING,
+					"found a subdomain with ssl_redirect=1 but parent-domain has ssl=0, integrity check fixed this");
 			} else {
 				// It's just the check, let the function fail
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "found a subdomain with ssl_redirect=1 but parent-domain has ssl=0, integrity check can fix this");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+					"found a subdomain with ssl_redirect=1 but parent-domain has ssl=0, integrity check can fix this");
 				return false;
 			}
 		}
 
 		if ($fix) {
 			return $this->subdomainSslRedirect();
-		} else {
-			return true;
 		}
+		return true;
 	}
 
 	/**
 	 * Check if all subdomain have letsencrypt = 0 if domain has no ssl-port
 	 *
-	 * @param bool $fix
-	 *            Fix everything found directly
+	 * @param bool $fix fix everything found directly
+	 *
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public function subdomainLetsencrypt($fix = false)
+	public function subdomainLetsencrypt(bool $fix = false): bool
 	{
 		$ips = [];
 		$parentdomains = [];
@@ -384,31 +398,32 @@ class IntegrityCheck
 				Database::pexecute($upd_stmt, [
 					'domainid' => $id
 				]);
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING, "found a subdomain with letsencrypt=1 but parent-domain has ssl=0, integrity check fixed this");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_WARNING,
+					"found a subdomain with letsencrypt=1 but parent-domain has ssl=0, integrity check fixed this");
 			} else {
 				// It's just the check, let the function fail
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "found a subdomain with letsencrypt=1 but parent-domain has ssl=0, integrity check can fix this");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+					"found a subdomain with letsencrypt=1 but parent-domain has ssl=0, integrity check can fix this");
 				return false;
 			}
 		}
 
 		if ($fix) {
 			return $this->subdomainLetsencrypt();
-		} else {
-			return true;
 		}
+		return true;
 	}
 
 	/**
 	 * check whether the webserveruser is in
 	 * the customers groups when fcgid / php-fpm is used
 	 *
-	 * @param bool $fix
-	 *            fix member/groups
+	 * @param bool $fix fix member/groups
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public function webserverGroupMemberForFcgidPhpFpm($fix = false)
+	public function webserverGroupMemberForFcgidPhpFpm(bool $fix = false): bool
 	{
 		if (Settings::Get('system.mod_fcgid') == 0 && Settings::Get('phpfpm.enabled') == 0) {
 			return true;
@@ -423,7 +438,8 @@ class IntegrityCheck
 		]);
 
 		if ($cwg_stmt->rowCount() > 0) {
-			$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "Customers are missing the webserver-user as group-member, integrity-check can fix that");
+			$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+				"Customers are missing the webserver-user as group-member, integrity-check can fix that");
 			if ($fix) {
 				// prepare update statement
 				$upd_stmt = Database::prepare("
@@ -438,7 +454,8 @@ class IntegrityCheck
 					$upd_data['id'] = $cwg_row['id'];
 					Database::pexecute($upd_stmt, $upd_data);
 				}
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "Customers were missing the webserver-user as group-member, integrity-check fixed that");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+					"Customers were missing the webserver-user as group-member, integrity-check fixed that");
 			} else {
 				return false;
 			}
@@ -455,12 +472,12 @@ class IntegrityCheck
 	 * the customers groups when fcgid / php-fpm and
 	 * fcgid/fpm in froxlor vhost is used
 	 *
-	 * @param bool $fix
-	 *            fix member/groups
+	 * @param bool $fix fix member/groups
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public function froxlorLocalGroupMemberForFcgidPhpFpm($fix = false)
+	public function froxlorLocalGroupMemberForFcgidPhpFpm(bool $fix = false): bool
 	{
 		if (Settings::Get('system.mod_fcgid') == 0 && Settings::Get('phpfpm.enabled') == 0) {
 			return true;
@@ -491,7 +508,8 @@ class IntegrityCheck
 		]);
 
 		if ($cwg_stmt->rowCount() > 0) {
-			$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "Customers are missing the local froxlor-user as group-member, integrity-check can fix that");
+			$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+				"Customers are missing the local froxlor-user as group-member, integrity-check can fix that");
 			if ($fix) {
 				// prepare update statement
 				$upd_stmt = Database::prepare("
@@ -506,7 +524,8 @@ class IntegrityCheck
 					$upd_data['id'] = $cwg_row['id'];
 					Database::pexecute($upd_stmt, $upd_data);
 				}
-				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE, "Customers were missing the local froxlor-user as group-member, integrity-check fixed that");
+				$this->log->logAction(FroxlorLogger::ADM_ACTION, LOG_NOTICE,
+					"Customers were missing the local froxlor-user as group-member, integrity-check fixed that");
 			} else {
 				return false;
 			}
diff --git a/lib/Froxlor/Database/Manager/DbManagerMySQL.php b/lib/Froxlor/Database/Manager/DbManagerMySQL.php
index 3114d02e..470daa87 100644
--- a/lib/Froxlor/Database/Manager/DbManagerMySQL.php
+++ b/lib/Froxlor/Database/Manager/DbManagerMySQL.php
@@ -48,7 +48,7 @@ class DbManagerMySQL
 	/**
 	 * main constructor
 	 *
-	 * @param FroxlorLogger $log
+	 * @param FroxlorLogger|null $log
 	 */
 	public function __construct(&$log = null)
 	{
@@ -58,9 +58,9 @@ class DbManagerMySQL
 	/**
 	 * creates a database
 	 *
-	 * @param string $dbname
+	 * @param string|null $dbname
 	 */
-	public function createDatabase($dbname = null)
+	public function createDatabase(string $dbname = null)
 	{
 		Database::query("CREATE DATABASE `" . $dbname . "`");
 	}
@@ -71,13 +71,14 @@ class DbManagerMySQL
 	 *
 	 * @param string $username
 	 * @param string|array $password
-	 * @param string $access_host
+	 * @param ?string $access_host
 	 * @param bool $p_encrypted
 	 *            optional, whether the password is encrypted or not, default false
 	 * @param bool $update
 	 *            optional, whether to update the password only (not create user)
+	 * @throws \Exception
 	 */
-	public function grantPrivilegesTo($username = null, $password = null, $access_host = null, $p_encrypted = false, $update = false)
+	public function grantPrivilegesTo(string $username, $password, string $access_host = null, bool $p_encrypted = false, bool $update = false)
 	{
 		$pwd_plugin = 'mysql_native_password';
 		if (is_array($password) && count($password) == 2) {
@@ -141,8 +142,9 @@ class DbManagerMySQL
 	 * takes away any privileges from a user to that db
 	 *
 	 * @param string $dbname
+	 * @throws \Exception
 	 */
-	public function deleteDatabase($dbname = null)
+	public function deleteDatabase(string $dbname)
 	{
 		if (version_compare(Database::getAttribute(PDO::ATTR_SERVER_VERSION), '5.0.2', '<')) {
 			// failsafe if user has been deleted manually (requires MySQL 4.1.2+)
@@ -178,8 +180,9 @@ class DbManagerMySQL
 	 *
 	 * @param string $username
 	 * @param string $host
+	 * @throws \Exception
 	 */
-	public function deleteUser($username = null, $host = null)
+	public function deleteUser(string $username, string $host)
 	{
 		if (Database::getAttribute(PDO::ATTR_SERVER_VERSION) < '5.0.2') {
 			// Revoke privileges (only required for MySQL 4.1.2 - 5.0.1)
@@ -203,9 +206,9 @@ class DbManagerMySQL
 	 *
 	 * @param string $username
 	 * @param string $host
-	 *            (unused in mysql)
+	 * @throws \Exception
 	 */
-	public function disableUser($username = null, $host = null)
+	public function disableUser(string $username, string $host)
 	{
 		$stmt = Database::prepare('REVOKE ALL PRIVILEGES, GRANT OPTION FROM `' . $username . '`@`' . $host . '`');
 		Database::pexecute($stmt, [], false);
@@ -216,8 +219,9 @@ class DbManagerMySQL
 	 *
 	 * @param string $username
 	 * @param string $host
+	 * @throws \Exception
 	 */
-	public function enableUser($username = null, $host = null)
+	public function enableUser(string $username, string $host)
 	{
 		// check whether user exists to avoid errors
 		$exist_check_stmt = Database::prepare("SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = '" . $username . "' AND host = '" . $host . "')");
@@ -239,14 +243,14 @@ class DbManagerMySQL
 	/**
 	 * return an array of all usernames used in that DBMS
 	 *
-	 * @param bool $user_only
-	 *            if false, * will be selected from mysql.user and slightly different array will be generated
+	 * @param bool $user_only if false, will be selected from mysql.user and slightly different array will be generated
 	 *
 	 * @return array
+	 * @throws \Exception
 	 */
-	public function getAllSqlUsers($user_only = true)
+	public function getAllSqlUsers(bool $user_only = true): array
 	{
-		if ($user_only == false) {
+		if (!$user_only) {
 			$result_stmt = Database::prepare('SELECT * FROM mysql.user');
 		} else {
 			$result_stmt = Database::prepare('SELECT `User` FROM mysql.user');
diff --git a/lib/Froxlor/Dns/Dns.php b/lib/Froxlor/Dns/Dns.php
index 951fa050..7ed025a6 100644
--- a/lib/Froxlor/Dns/Dns.php
+++ b/lib/Froxlor/Dns/Dns.php
@@ -33,7 +33,15 @@ use PDO;
 
 class Dns
 {
-	public static function getAllowedDomainEntry($domain_id, $area = 'customer', $userinfo = [])
+	/**
+	 * @param int $domain_id
+	 * @param string $area
+	 * @param array $userinfo
+	 *
+	 * @return string|void
+	 * @throws \Exception
+	 */
+	public static function getAllowedDomainEntry(int $domain_id, string $area = 'customer', array $userinfo = [])
 	{
 		$dom_data = [
 			'did' => $domain_id
@@ -67,7 +75,15 @@ class Dns
 		Response::standardError('dns_notfoundorallowed');
 	}
 
-	public static function createDomainZone($domain_id, $froxlorhostname = false, $isMainButSubTo = false)
+	/**
+	 * @param int|array $domain_id id of domain or in case of froxlorhostname, a domain-array with the needed data
+	 * @param bool $froxlorhostname
+	 * @param bool $isMainButSubTo
+	 *
+	 * @return DnsZone|void
+	 * @throws \Exception
+	 */
+	public static function createDomainZone($domain_id, bool $froxlorhostname = false, bool $isMainButSubTo = false)
 	{
 		if (!$froxlorhostname) {
 			// get domain-name
@@ -146,16 +162,22 @@ class Dns
 			while ($subdomain = $subdomains_stmt->fetch(PDO::FETCH_ASSOC)) {
 				// Listing domains is enough as there currently is no support for choosing
 				// different ips for a subdomain => use same IPs as toplevel
-				self::addRequiredEntry(str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'A', $required_entries);
-				self::addRequiredEntry(str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'AAAA', $required_entries);
+				self::addRequiredEntry(str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'A',
+					$required_entries);
+				self::addRequiredEntry(str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'AAAA',
+					$required_entries);
 
 				// Check whether to add a www.-prefix
 				if ($subdomain['iswildcarddomain'] == '1') {
-					self::addRequiredEntry('*.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'A', $required_entries);
-					self::addRequiredEntry('*.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'AAAA', $required_entries);
+					self::addRequiredEntry('*.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'A',
+						$required_entries);
+					self::addRequiredEntry('*.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']),
+						'AAAA', $required_entries);
 				} elseif ($subdomain['wwwserveralias'] == '1') {
-					self::addRequiredEntry('www.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'A', $required_entries);
-					self::addRequiredEntry('www.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'AAAA', $required_entries);
+					self::addRequiredEntry('www.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']), 'A',
+						$required_entries);
+					self::addRequiredEntry('www.' . str_replace('.' . $domain['domain'], '', $subdomain['domain']),
+						'AAAA', $required_entries);
 				}
 			}
 		}
@@ -200,14 +222,17 @@ class Dns
 
 		// now generate all records and unset the required entries we have
 		foreach ($dom_entries as $entry) {
-			if (array_key_exists($entry['type'], $required_entries) && array_key_exists(md5($entry['record']), $required_entries[$entry['type']])) {
+			if (array_key_exists($entry['type'], $required_entries) && array_key_exists(md5($entry['record']),
+					$required_entries[$entry['type']])) {
 				unset($required_entries[$entry['type']][md5($entry['record'])]);
 			}
-			if (Settings::Get('system.dns_createcaaentry') == '1' && $entry['type'] == 'CAA' && strtolower(substr($entry['content'], 0, 7)) == '"v=caa1') {
+			if (Settings::Get('system.dns_createcaaentry') == '1' && $entry['type'] == 'CAA' && strtolower(substr($entry['content'],
+					0, 7)) == '"v=caa1') {
 				// unset special CAA required-entry
 				unset($required_entries[$entry['type']][md5("@CAA@")]);
 			}
-			if (Settings::Get('spf.use_spf') == '1' && $entry['type'] == 'TXT' && $entry['record'] == '@' && (strtolower(substr($entry['content'], 0, 7)) == '"v=spf1' || strtolower(substr($entry['content'], 0, 6)) == 'v=spf1')) {
+			if (Settings::Get('spf.use_spf') == '1' && $entry['type'] == 'TXT' && $entry['record'] == '@' && (strtolower(substr($entry['content'],
+						0, 7)) == '"v=spf1' || strtolower(substr($entry['content'], 0, 6)) == 'v=spf1')) {
 				// unset special spf required-entry
 				unset($required_entries[$entry['type']][md5("@SPF@")]);
 			}
@@ -223,7 +248,8 @@ class Dns
 					'*'
 				] as $crecord
 			) {
-				if ($entry['type'] == 'CNAME' && $entry['record'] == '@' && (array_key_exists(md5($crecord), $required_entries['A']) || array_key_exists(md5($crecord), $required_entries['AAAA']))) {
+				if ($entry['type'] == 'CNAME' && $entry['record'] == '@' && (array_key_exists(md5($crecord),
+							$required_entries['A']) || array_key_exists(md5($crecord), $required_entries['AAAA']))) {
 					unset($required_entries['A'][md5($crecord)]);
 					unset($required_entries['AAAA'][md5($crecord)]);
 				}
@@ -238,13 +264,16 @@ class Dns
 						'smtp'
 					] as $crecord
 				) {
-					if ($entry['type'] == 'CNAME' && $entry['record'] == $crecord && (array_key_exists(md5($crecord), $required_entries['A']) || array_key_exists(md5($crecord), $required_entries['AAAA']))) {
+					if ($entry['type'] == 'CNAME' && $entry['record'] == $crecord && (array_key_exists(md5($crecord),
+								$required_entries['A']) || array_key_exists(md5($crecord),
+								$required_entries['AAAA']))) {
 						unset($required_entries['A'][md5($crecord)]);
 						unset($required_entries['AAAA'][md5($crecord)]);
 					}
 				}
 			}
-			$zonerecords[] = new DnsEntry($entry['record'], $entry['type'], $entry['content'], $entry['prio'], $entry['ttl']);
+			$zonerecords[] = new DnsEntry($entry['record'], $entry['type'], $entry['content'], $entry['prio'],
+				$entry['ttl']);
 		}
 
 		// add missing required entries
@@ -275,7 +304,8 @@ class Dns
 						foreach ($records as $record) {
 							if ($type == 'A' && filter_var($ip['ip'], FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false) {
 								$zonerecords[] = new DnsEntry($record, 'A', $ip['ip']);
-							} elseif ($type == 'AAAA' && filter_var($ip['ip'], FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) !== false) {
+							} elseif ($type == 'AAAA' && filter_var($ip['ip'], FILTER_VALIDATE_IP,
+									FILTER_FLAG_IPV6) !== false) {
 								$zonerecords[] = new DnsEntry($record, 'AAAA', $ip['ip']);
 							}
 						}
@@ -356,7 +386,8 @@ class Dns
 								if (substr($dkim_entries[0], 0, 1) == '(') {
 									$multiline = true;
 								}
-								$zonerecords[] = new DnsEntry($record, 'TXT', self::encloseTXTContent($dkim_entries[0], $multiline));
+								$zonerecords[] = new DnsEntry($record, 'TXT',
+									self::encloseTXTContent($dkim_entries[0], $multiline));
 							}
 						}
 					}
@@ -416,7 +447,8 @@ class Dns
 
 		if (!$isMainButSubTo) {
 			$date = date('Ymd');
-			$domain['bindserial'] = (preg_match('/^' . $date . '/', $domain['bindserial']) ? $domain['bindserial'] + 1 : $date . '00');
+			$domain['bindserial'] = (preg_match('/^' . $date . '/',
+				$domain['bindserial']) ? $domain['bindserial'] + 1 : $date . '00');
 			if (!$froxlorhostname) {
 				$upd_stmt = Database::prepare("
 					UPDATE `" . TABLE_PANEL_DOMAINS . "` SET
@@ -443,12 +475,19 @@ class Dns
 			array_unshift($zonerecords, $soa_record);
 		}
 
-		$zone = new DnsZone((int)Settings::Get('system.defaultttl'), $domain['domain'], $domain['bindserial'], $zonerecords);
+		$zone = new DnsZone((int)Settings::Get('system.defaultttl'), $domain['domain'], $domain['bindserial'],
+			$zonerecords);
 
 		return $zone;
 	}
 
-	private static function addRequiredEntry($record = '@', $type = 'A', &$required = [])
+	/**
+	 * @param string $record
+	 * @param string $type
+	 * @param array $required
+	 * @return void
+	 */
+	private static function addRequiredEntry(string $record = '@', string $type = 'A', array &$required = [])
 	{
 		if (!isset($required[$type])) {
 			$required[$type] = [];
@@ -456,7 +495,11 @@ class Dns
 		$required[$type][md5($record)] = $record;
 	}
 
-	private static function generateDkimEntries($domain)
+	/**
+	 * @param array $domain
+	 * @return array
+	 */
+	private static function generateDkimEntries(array $domain): array
 	{
 		$zone_dkim = [];
 
@@ -486,7 +529,8 @@ class Dns
 			}
 
 			// key
-			$dkim_txt .= 'k=rsa;p=' . trim(preg_replace('/-----BEGIN PUBLIC KEY-----(.+)-----END PUBLIC KEY-----/s', '$1', str_replace("\n", '', $domain['dkim_pubkey']))) . ';';
+			$dkim_txt .= 'k=rsa;p=' . trim(preg_replace('/-----BEGIN PUBLIC KEY-----(.+)-----END PUBLIC KEY-----/s',
+					'$1', str_replace("\n", '', $domain['dkim_pubkey']))) . ';';
 
 			// service-type
 			if (Settings::Get('dkim.dkim_servicetype') == '1') {
@@ -503,10 +547,15 @@ class Dns
 		return $zone_dkim;
 	}
 
-	public static function encloseTXTContent($txt_content, $isMultiLine = false)
+	/**
+	 * @param string $txt_content
+	 * @param bool $isMultiLine
+	 * @return string
+	 */
+	public static function encloseTXTContent(string $txt_content, bool $isMultiLine = false): string
 	{
 		// check that TXT content is enclosed in " "
-		if ($isMultiLine == false && Settings::Get('system.dns_server') != 'PowerDNS') {
+		if (!$isMultiLine && Settings::Get('system.dns_server') != 'PowerDNS') {
 			if (substr($txt_content, 0, 1) != '"') {
 				$txt_content = '"' . $txt_content;
 			}
@@ -526,10 +575,13 @@ class Dns
 		return $txt_content;
 	}
 
-	private static function escapeSoaAdminMail($email)
+	/**
+	 * @param string $email
+	 * @return string
+	 */
+	private static function escapeSoaAdminMail(string $email): string
 	{
 		$mail_parts = explode("@", $email);
-		$escpd_mail = str_replace(".", "\.", $mail_parts[0]) . "." . $mail_parts[1] . ".";
-		return $escpd_mail;
+		return str_replace(".", "\.", $mail_parts[0]) . "." . $mail_parts[1] . ".";
 	}
 }
diff --git a/lib/Froxlor/Dns/DnsEntry.php b/lib/Froxlor/Dns/DnsEntry.php
index e2e8c8f3..ade8f570 100644
--- a/lib/Froxlor/Dns/DnsEntry.php
+++ b/lib/Froxlor/Dns/DnsEntry.php
@@ -29,14 +29,22 @@ use Froxlor\Settings;
 
 class DnsEntry
 {
-	public $record;
-	public $ttl;
-	public $class = 'IN';
-	public $type;
-	public $priority;
-	public $content;
+	public string $record;
+	public int $ttl;
+	public string $class = 'IN';
+	public string $type;
+	public int $priority;
+	public ?string $content;
 
-	public function __construct($record = '', $type = 'A', $content = null, $prio = 0, $ttl = 0, $class = 'IN')
+	/**
+	 * @param string $record
+	 * @param string $type
+	 * @param string|null $content
+	 * @param int $prio
+	 * @param int $ttl
+	 * @param string $class
+	 */
+	public function __construct(string $record = '', string $type = 'A', string $content = null, int $prio = 0, int $ttl = 0, string $class = 'IN')
 	{
 		$this->record = $record;
 		$this->type = $type;
@@ -72,7 +80,6 @@ class DnsEntry
 			// last line
 			$_content .= "\t\t\t\t" . '"' . $_l . '")';
 		}
-		$result = $this->record . "\t" . $this->ttl . "\t" . $this->class . "\t" . $this->type . "\t" . (($this->priority >= 0 && ($this->type == 'MX' || $this->type == 'SRV')) ? $this->priority . "\t" : "") . $_content . PHP_EOL;
-		return $result;
+		return $this->record . "\t" . $this->ttl . "\t" . $this->class . "\t" . $this->type . "\t" . (($this->priority >= 0 && ($this->type == 'MX' || $this->type == 'SRV')) ? $this->priority . "\t" : "") . $_content . PHP_EOL;
 	}
 }
diff --git a/lib/Froxlor/Dns/DnsZone.php b/lib/Froxlor/Dns/DnsZone.php
index 5fb4d22b..3e4eea46 100644
--- a/lib/Froxlor/Dns/DnsZone.php
+++ b/lib/Froxlor/Dns/DnsZone.php
@@ -29,12 +29,18 @@ use Froxlor\Settings;
 
 class DnsZone
 {
-	public $ttl;
-	public $origin;
-	public $serial;
-	public $records;
+	public int $ttl;
+	public string $origin;
+	public string $serial;
+	public ?array $records;
 
-	public function __construct($ttl = 0, $origin = '', $serial = '', $records = null)
+	/**
+	 * @param int $ttl
+	 * @param string $origin
+	 * @param string $serial
+	 * @param array|null $records
+	 */
+	public function __construct(int $ttl = 0, string $origin = '', string $serial = '', array $records = null)
 	{
 		$this->ttl = ($ttl <= 0 ? Settings::Get('system.defaultttl') : $ttl);
 		$this->origin = $origin;
@@ -44,13 +50,13 @@ class DnsZone
 
 	public function __toString()
 	{
-		$_zonefile = "\$TTL " . $this->ttl . PHP_EOL;
-		$_zonefile .= "\$ORIGIN " . $this->origin . "." . PHP_EOL;
+		$zone_file = "\$TTL " . $this->ttl . PHP_EOL;
+		$zone_file .= "\$ORIGIN " . $this->origin . "." . PHP_EOL;
 		if (!empty($this->records)) {
 			foreach ($this->records as $record) {
-				$_zonefile .= (string)$record;
+				$zone_file .= (string)$record;
 			}
 		}
-		return $_zonefile;
+		return $zone_file;
 	}
 }
diff --git a/lib/Froxlor/Dns/PowerDNS.php b/lib/Froxlor/Dns/PowerDNS.php
index 33c864eb..f1a3aef1 100644
--- a/lib/Froxlor/Dns/PowerDNS.php
+++ b/lib/Froxlor/Dns/PowerDNS.php
@@ -37,9 +37,9 @@ class PowerDNS
 	/**
 	 * remove all records and entries of a given domain
 	 *
-	 * @param array $domain
+	 * @param array|null $domain
 	 */
-	public static function cleanDomainZone($domain = null)
+	public static function cleanDomainZone(array $domain = null)
 	{
 		if (is_array($domain) && isset($domain['domain'])) {
 			$pdns_domains_stmt = self::getDB()->prepare("SELECT `id`, `name` FROM `domains` WHERE `name` = :domain");
@@ -67,16 +67,19 @@ class PowerDNS
 	/**
 	 * get pdo database connection to powerdns database
 	 *
-	 * @return PDO
+	 * @return \PDO
 	 */
-	public static function getDB()
+	public static function getDB(): \PDO
 	{
-		if (!isset(self::$pdns_db) || (self::$pdns_db instanceof PDO) == false) {
+		if (!isset(self::$pdns_db) || !(self::$pdns_db instanceof PDO)) {
 			self::connectToPdnsDb();
 		}
 		return self::$pdns_db;
 	}
 
+	/**
+	 * @return void
+	 */
 	private static function connectToPdnsDb()
 	{
 		// get froxlor pdns config
diff --git a/lib/Froxlor/Domain/Domain.php b/lib/Froxlor/Domain/Domain.php
index c5dd7f9d..ebc16eb0 100644
--- a/lib/Froxlor/Domain/Domain.php
+++ b/lib/Froxlor/Domain/Domain.php
@@ -41,8 +41,9 @@ class Domain
 	 *
 	 * @param int $domain_id
 	 * @return array
+	 * @throws \Exception
 	 */
-	public static function getIpsOfDomain($domain_id)
+	public static function getIpsOfDomain(int $domain_id = 0): array
 	{
 		if ($domain_id > 0) {
 			$sel_stmt = Database::prepare("
@@ -75,7 +76,7 @@ class Domain
 	 *
 	 * @return array array of enabled redirect-codes
 	 */
-	public static function getRedirectCodesArray()
+	public static function getRedirectCodesArray(): array
 	{
 		$sql = "SELECT * FROM `" . TABLE_PANEL_REDIRECTCODES . "` WHERE `enabled` = '1' ORDER BY `id` ASC";
 		$result_stmt = Database::query($sql);
@@ -92,12 +93,12 @@ class Domain
 	 * returns the redirect-code for a given
 	 * domain-id
 	 *
-	 * @param integer $domainid
-	 *            id of the domain
+	 * @param int $domainid id of the domain
 	 *
 	 * @return string redirect-code
+	 * @throws \Exception
 	 */
-	public static function getDomainRedirectCode($domainid = 0)
+	public static function getDomainRedirectCode(int $domainid = 0): string
 	{
 		// get system default
 		$default = '301';
@@ -128,12 +129,11 @@ class Domain
 	 * return an array of all enabled redirect-codes
 	 * for the settings form
 	 *
-	 * @param bool $add_desc
-	 *            optional, default true, add the code-description
+	 * @param bool $add_desc optional, default true, add the code-description
 	 *
 	 * @return array array of enabled redirect-codes
 	 */
-	public static function getRedirectCodes($add_desc = true)
+	public static function getRedirectCodes(bool $add_desc = true): array
 	{
 		$sql = "SELECT * FROM `" . TABLE_PANEL_REDIRECTCODES . "` WHERE `enabled` = '1' ORDER BY `id` ASC";
 		$result_stmt = Database::query($sql);
@@ -153,12 +153,12 @@ class Domain
 	 * returns the redirect-id for a given
 	 * domain-id
 	 *
-	 * @param integer $domainid
-	 *            id of the domain
+	 * @param int $domainid id of the domain
 	 *
-	 * @return integer redirect-code-id
+	 * @return int redirect-code-id
+	 * @throws \Exception
 	 */
-	public static function getDomainRedirectId($domainid = 0)
+	public static function getDomainRedirectId(int $domainid = 0): int
 	{
 		$code = 1;
 		if ($domainid > 0) {
@@ -171,7 +171,7 @@ class Domain
 				'domainid' => $domainid
 			]);
 
-			if (is_array($result) && isset($result['redirect'])) {
+			if ($result && isset($result['redirect'])) {
 				$code = (int)$result['redirect'];
 			}
 		}
@@ -179,16 +179,15 @@ class Domain
 	}
 
 	/**
-	 * adds a redirectcode for a domain
+	 * adds a redirect-code for a domain
 	 *
-	 * @param integer $domainid
-	 *            id of the domain to add the code for
-	 * @param integer $redirect
-	 *            selected redirect-id
+	 * @param int $domainid id of the domain to add the code for
+	 * @param int $redirect selected redirect-id
 	 *
 	 * @return null
+	 * @throws \Exception
 	 */
-	public static function addRedirectToDomain($domainid = 0, $redirect = 1)
+	public static function addRedirectToDomain(int $domainid = 0, int $redirect = 1)
 	{
 		if ($domainid > 0) {
 			$ins_stmt = Database::prepare("
@@ -202,19 +201,18 @@ class Domain
 	}
 
 	/**
-	 * updates the redirectcode of a domain
+	 * updates the redirect-code of a domain
 	 * if redirect-code is false, nothing happens
 	 *
-	 * @param integer $domainid
-	 *            id of the domain to update
-	 * @param integer $redirect
-	 *            selected redirect-id or false
+	 * @param int $domainid id of the domain to update
+	 * @param int $redirect selected redirect-id
 	 *
 	 * @return null
+	 * @throws \Exception
 	 */
-	public static function updateRedirectOfDomain($domainid = 0, $redirect = false)
+	public static function updateRedirectOfDomain(int $domainid = 0, int $redirect = 0)
 	{
-		if ($redirect == false) {
+		if (!$redirect) {
 			return;
 		}
 
@@ -240,12 +238,12 @@ class Domain
 	 * check whether a domain has subdomains added as full-domains
 	 * #329
 	 *
-	 * @param int $id
-	 *            domain-id
+	 * @param int $id domain-id
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function domainHasMainSubDomains($id = 0)
+	public static function domainHasMainSubDomains(int $id): bool
 	{
 		$result_stmt = Database::prepare("
 		SELECT COUNT(`id`) as `mainsubs` FROM `" . TABLE_PANEL_DOMAINS . "`
@@ -254,8 +252,8 @@ class Domain
 			'id' => $id
 		]);
 
-		if (isset($result['mainsubs']) && $result['mainsubs'] > 0) {
-			return true;
+		if ($result && isset($result['mainsubs'])) {
+			return $result['mainsubs'] > 0;
 		}
 		return false;
 	}
@@ -264,12 +262,12 @@ class Domain
 	 * check whether a subof-domain exists
 	 * #329
 	 *
-	 * @param int $id
-	 *            subof-domain-id
+	 * @param int $id subof-domain-id
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function domainMainToSubExists($id = 0)
+	public static function domainMainToSubExists(int $id): bool
 	{
 		$result_stmt = Database::prepare("
 		SELECT `id` FROM `" . TABLE_PANEL_DOMAINS . "` WHERE `id` = :id");
@@ -278,8 +276,8 @@ class Domain
 		]);
 		$result = $result_stmt->fetch(PDO::FETCH_ASSOC);
 
-		if (isset($result['id']) && $result['id'] > 0) {
-			return true;
+		if ($result && isset($result['id'])) {
+			return $result['id'] > 0;
 		}
 		return false;
 	}
@@ -289,9 +287,10 @@ class Domain
 	 *
 	 * @param int $domainid
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function domainHasSslIpPort($domainid = 0)
+	public static function domainHasSslIpPort(int $domainid): bool
 	{
 		$result_stmt = Database::prepare("
 			SELECT `dt`.* FROM `" . TABLE_DOMAINTOIP . "` `dt`, `" . TABLE_PANEL_IPSANDPORTS . "` `iap`
@@ -301,7 +300,7 @@ class Domain
 		]);
 		$result = $result_stmt->fetch(PDO::FETCH_ASSOC);
 
-		if (is_array($result) && isset($result['id_ipandports'])) {
+		if ($result && isset($result['id_ipandports'])) {
 			return true;
 		}
 		return false;
@@ -311,12 +310,12 @@ class Domain
 	 * returns true or false whether a given domain id
 	 * is the std-subdomain of a customer
 	 *
-	 * @param
-	 *            int domain-id
+	 * @param int $did domain-id
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function isCustomerStdSubdomain($did = 0)
+	public static function isCustomerStdSubdomain(int $did): bool
 	{
 		if ($did > 0) {
 			$result_stmt = Database::prepare("
@@ -327,17 +326,27 @@ class Domain
 				'did' => $did
 			]);
 
-			if (is_array($result) && isset($result['customerid']) && $result['customerid'] > 0) {
-				return true;
+			if ($result && isset($result['customerid'])) {
+				return $result['customerid'] > 0;
 			}
 		}
 		return false;
 	}
 
-	public static function triggerLetsEncryptCSRForAliasDestinationDomain($aliasDestinationDomainID, $log)
-	{
-		if (isset($aliasDestinationDomainID) && $aliasDestinationDomainID > 0) {
-			$log->logAction(FroxlorLogger::ADM_ACTION, LOG_INFO, "LetsEncrypt CSR triggered for domain ID " . $aliasDestinationDomainID);
+	/**
+	 * @param int $aliasDestinationDomainID
+	 * @param FroxlorLogger $log
+	 *
+	 * @return void
+	 * @throws \Exception
+	 */
+	public static function triggerLetsEncryptCSRForAliasDestinationDomain(
+		int $aliasDestinationDomainID,
+		FroxlorLogger $log
+	) {
+		if ($aliasDestinationDomainID > 0) {
+			$log->logAction(FroxlorLogger::ADM_ACTION, LOG_INFO,
+				"LetsEncrypt CSR triggered for domain ID " . $aliasDestinationDomainID);
 			$upd_stmt = Database::prepare("UPDATE
 					`" . TABLE_PANEL_DOMAIN_SSL_SETTINGS . "`
 				SET
@@ -351,7 +360,11 @@ class Domain
 		}
 	}
 
-	public static function doLetsEncryptCleanUp($domainname = null)
+	/**
+	 * @param string $domainname
+	 * @return true
+	 */
+	public static function doLetsEncryptCleanUp(string $domainname): bool
 	{
 		// @ see \Froxlor\Cron\Http\LetsEncrypt\AcmeSh.php
 		$acmesh = AcmeSh::getAcmeSh();
@@ -374,18 +387,19 @@ class Domain
 	/**
 	 * checks give path for security issues
 	 * and returns a string that can be appended
-	 * to a line for a open_basedir directive
+	 * to a line for an open_basedir directive
 	 *
-	 * @param string $path
-	 *            the path to check and append
-	 * @param boolean $first
-	 *            if true, no ':' will be prefixed to the path
+	 * @param string $path the path to check and append
+	 * @param bool $first if true, no ':' will be prefixed to the path
 	 *
 	 * @return string
+	 * @throws \Exception
 	 */
-	public static function appendOpenBasedirPath($path = '', $first = false)
+	public static function appendOpenBasedirPath(string $path = '', bool $first = false): string
 	{
-		if ($path != '' && $path != '/' && (!preg_match("#^/dev#i", $path) || preg_match("#^/dev/urandom#i", $path)) && !preg_match("#^/proc#i", $path) && !preg_match("#^/etc#i", $path) && !preg_match("#^/sys#i", $path) && !preg_match("#:#", $path)) {
+		if ($path != '' && $path != '/' && (!preg_match("#^/dev#i", $path) || preg_match("#^/dev/urandom#i",
+					$path)) && !preg_match("#^/proc#i", $path) && !preg_match("#^/etc#i",
+				$path) && !preg_match("#^/sys#i", $path) && !preg_match("#:#", $path)) {
 			if (preg_match("#^/dev/urandom#i", $path)) {
 				$path = FileDir::makeCorrectFile($path);
 			} else {
@@ -394,7 +408,7 @@ class Domain
 
 			// check for php-version that requires the trailing
 			// slash to be removed as it does not allow the usage
-			// of the subfolders within the given folder, fixes #797
+			// of the sub-folders within the given folder, fixes #797
 			if ((PHP_MINOR_VERSION == 2 && PHP_VERSION_ID >= 50216) || PHP_VERSION_ID >= 50304) {
 				// check trailing slash
 				if (substr($path, -1, 1) == '/') {
diff --git a/lib/Froxlor/Domain/IpAddr.php b/lib/Froxlor/Domain/IpAddr.php
index 5bc76f44..1c6f5cdf 100644
--- a/lib/Froxlor/Domain/IpAddr.php
+++ b/lib/Froxlor/Domain/IpAddr.php
@@ -30,8 +30,10 @@ use PDO;
 
 class IpAddr
 {
-
-	public static function getIpAddresses()
+	/**
+	 * @return array
+	 */
+	public static function getIpAddresses(): array
 	{
 		$result_stmt = Database::query("
 			SELECT `id`, `ip`, `port` FROM `" . TABLE_PANEL_IPSANDPORTS . "` ORDER BY `ip` ASC, `port` ASC
@@ -51,14 +53,22 @@ class IpAddr
 		return $system_ipaddress_array;
 	}
 
-	public static function getSslIpPortCombinations()
+	/**
+	 * @return array
+	 */
+	public static function getSslIpPortCombinations(): array
 	{
 		return [
 				'' => lng('panel.none_value')
 			] + self::getIpPortCombinations(true);
 	}
 
-	public static function getIpPortCombinations($ssl = false)
+	/**
+	 * @param bool $ssl
+	 * @return array
+	 * @throws \Exception
+	 */
+	public static function getIpPortCombinations(bool $ssl = false): array
 	{
 		global $userinfo;
 
diff --git a/lib/Froxlor/FileDir.php b/lib/Froxlor/FileDir.php
index 37f2af2c..79f60b75 100644
--- a/lib/Froxlor/FileDir.php
+++ b/lib/Froxlor/FileDir.php
@@ -38,30 +38,24 @@ class FileDir
 	 * which had to be created below with correct Owner/Group
 	 * (Copied from cron_tasks.php:rev1189 as we'll need this more often in future)
 	 *
-	 * @param string $homeDir
-	 *            The homedir of the user
-	 * @param string $dirToCreate
-	 *            The dir which should be created
-	 * @param int $uid
-	 *            The uid of the user
-	 * @param int $gid
-	 *            The gid of the user
-	 * @param bool $placeindex
-	 *            Place standard-index.html into the new folder
-	 * @param bool $allow_notwithinhomedir
-	 *            Allow creating a directory out of the customers docroot
+	 * @param string $homeDir The homedir of the user
+	 * @param string $dirToCreate The dir which should be created
+	 * @param int $uid The uid of the user
+	 * @param int $gid The gid of the user
+	 * @param bool $placeindex Place standard-index.html into the new folder
+	 * @param bool $allow_notwithinhomedir Allow creating a directory out of the customers docroot
 	 *
 	 * @return bool true if everything went okay, false if something went wrong
 	 * @throws Exception
 	 */
 	public static function mkDirWithCorrectOwnership(
-		$homeDir,
-		$dirToCreate,
-		$uid,
-		$gid,
-		$placeindex = false,
-		$allow_notwithinhomedir = false
-	) {
+		string $homeDir,
+		string $dirToCreate,
+		int $uid,
+		int $gid,
+		bool $placeindex = false,
+		bool $allow_notwithinhomedir = false
+	): bool {
 		if ($homeDir != '' && $dirToCreate != '') {
 			$homeDir = self::makeCorrectDir($homeDir);
 			$dirToCreate = self::makeCorrectDir($dirToCreate);
@@ -116,15 +110,14 @@ class FileDir
 	 * Function which returns a correct dirname, means to add slashes at the beginning and at the end if there weren't
 	 * some
 	 *
-	 * @param string $path
-	 *            the path to correct
+	 * @param string $dir the path to correct
 	 *
 	 * @return string the corrected path
 	 * @throws Exception
 	 */
-	public static function makeCorrectDir($dir)
+	public static function makeCorrectDir(string $dir): string
 	{
-		if (is_string($dir) && strlen($dir) > 0) {
+		if (strlen($dir) > 0) {
 			$dir = trim($dir);
 			if (substr($dir, -1, 1) != '/') {
 				$dir .= '/';
@@ -140,12 +133,11 @@ class FileDir
 	/**
 	 * Function which returns a secure path, means to remove all multiple dots and slashes
 	 *
-	 * @param string $path
-	 *            the path to secure
+	 * @param string $path the path to secure
 	 *
 	 * @return string the corrected path
 	 */
-	public static function makeSecurePath($path)
+	public static function makeSecurePath(string $path): string
 	{
 		// check for bad characters, some are allowed with escaping,
 		// but we generally don't want them in our directory-names,
@@ -191,16 +183,13 @@ class FileDir
 	/**
 	 * Wrapper around the exec command.
 	 *
-	 * @param string $exec_string
-	 *            command to be executed
-	 * @param string $return_value
-	 *            referenced variable where the output is stored
-	 * @param array $allowedChars
-	 *            optional array of allowed characters in path/command
+	 * @param string $exec_string command to be executed
+	 * @param mixed $return_value referenced variable where the output is stored
+	 * @param ?array $allowedChars optional array of allowed characters in path/command
 	 *
 	 * @return array result of exec()
 	 */
-	public static function safe_exec($exec_string, &$return_value = false, $allowedChars = null)
+	public static function safe_exec(string $exec_string, &$return_value = false, $allowedChars = null)
 	{
 		$disallowed = [
 			';',
@@ -245,19 +234,20 @@ class FileDir
 	/**
 	 * store the default index-file in a given destination folder
 	 *
-	 * @param string $loginname
-	 *            customers loginname
-	 * @param string $destination
-	 *            path where to create the file
-	 * @param object $logger
-	 *            FroxlorLogger object
-	 * @param boolean $force
-	 *            force creation whatever the settings say (needed for task #2, create new user)
+	 * @param string $loginname customers loginname
+	 * @param string $destination path where to create the file
+	 * @param object $logger FroxlorLogger object
+	 * @param bool $force force creation whatever the settings say (needed for task #2, create new user)
 	 *
-	 * @return null
+	 * @return void
+	 * @throws Exception
 	 */
-	public static function storeDefaultIndex($loginname = null, $destination = null, $logger = null, $force = false)
-	{
+	public static function storeDefaultIndex(
+		string $loginname,
+		string $destination,
+		$logger = null,
+		bool $force = false
+	) {
 		if ($force || (int)Settings::Get('system.store_index_file_subs') == 1) {
 			$result_stmt = Database::prepare("
 			SELECT `t`.`value`, `c`.`email` AS `customer_email`, `a`.`email` AS `admin_email`, `c`.`loginname` AS `customer_login`, `a`.`loginname` AS `admin_login`
@@ -306,18 +296,16 @@ class FileDir
 				self::safe_exec('cp -a ' . Froxlor::getInstallDir() . '/templates/misc/standardcustomer/* ' . escapeshellarg($destination));
 			}
 		}
-		return;
 	}
 
 	/**
 	 * Function which returns a correct filename, means to add a slash at the beginning if there wasn't one
 	 *
-	 * @param string $filename
-	 *            the filename
+	 * @param string $filename the filename
 	 *
 	 * @return string the corrected filename
 	 */
-	public static function makeCorrectFile(string $filename)
+	public static function makeCorrectFile(string $filename): string
 	{
 		if (trim($filename) == '') {
 			$error = 'Given filename for function ' . __FUNCTION__ . ' is empty.' . "\n";
@@ -333,21 +321,19 @@ class FileDir
 			$filename = '/' . $filename;
 		}
 
-		$filename = self::makeSecurePath($filename);
-		return $filename;
+		return self::makeSecurePath($filename);
 	}
 
 	/**
 	 * checks a directory against disallowed paths which could
 	 * lead to a damaged system if you use them
 	 *
-	 * @param string $fieldname
-	 * @param array $fielddata
-	 * @param mixed $newfieldvalue
+	 * @param string|null $path
 	 *
-	 * @return boolean|array
+	 * @return bool
+	 * @throws Exception
 	 */
-	public static function checkDisallowedPaths($path = null)
+	public static function checkDisallowedPaths(string $path): bool
 	{
 		/*
 		 * disallow base-directories and /
@@ -385,12 +371,11 @@ class FileDir
 	/**
 	 * Function which returns a correct destination for Postfix Virtual Table
 	 *
-	 * @param
-	 *            string The destinations
+	 * @param string $destination The destinations
+	 *
 	 * @return string the corrected destinations
-	 * @author Florian Lippert <flo@syscp.org> (2003-2009)
 	 */
-	public static function makeCorrectDestination($destination)
+	public static function makeCorrectDestination(string $destination): string
 	{
 		$search = '/ +/';
 		$replace = ' ';
@@ -410,27 +395,25 @@ class FileDir
 	/**
 	 * Returns a valid html tag for the chosen $fieldType for paths
 	 *
-	 * @param
-	 *            string path The path to start searching in
-	 * @param
-	 *            integer uid The uid which must match the found directories
-	 * @param
-	 *            integer gid The gid which must match the found directories
-	 * @param
-	 *            string value the value for the input-field
+	 * @param string $path The path to start searching in
+	 * @param int $uid The uid which must match the found directories
+	 * @param int $gid The gid which must match the found directories
+	 * @param string $value the value for the input-field
+	 * @param bool $dom
 	 *
-	 * @return string The html tag for the chosen $fieldType
+	 * @return array
 	 *
-	 * @author Martin Burchert <martin.burchert@syscp.de>
+	 * @throws Exception
 	 * @author Manuel Bernhardt <manuel.bernhardt@syscp.de>
+	 * @author Martin Burchert <martin.burchert@syscp.de>
 	 */
-	public static function makePathfield($path, $uid, $gid, $value = '', $dom = false)
+	public static function makePathfield(string $path, int $uid, int $gid, string $value = '', bool $dom = false): array
 	{
 		$value = str_replace($path, '', $value);
 		$field = [];
 
 		// path is given without starting slash
-		// but dirList holds the paths with starting slash
+		// but dirList holds the paths with starting slash,
 		// so we just add one here to get the correct
 		// default path selected, #225
 		if (substr($value, 0, 1) != '/' && !$dom) {
@@ -484,16 +467,14 @@ class FileDir
 	 * This function checks every found directory if they match either $uid or $gid, if they do
 	 * the found directory is valid. It uses recursive-iterators to find subdirectories.
 	 *
-	 * @param string $path
-	 *            the path to start searching in
-	 * @param int $uid
-	 *            the uid which must match the found directories
-	 * @param int $gid
-	 *            the gid which must match the found directories
+	 * @param string $path the path to start searching in
+	 * @param int $uid the uid which must match the found directories
+	 * @param int $gid the gid which must match the found directories
 	 *
 	 * @return array Array of found valid paths
+	 * @throws Exception
 	 */
-	private static function findDirs($path, $uid, $gid)
+	private static function findDirs(string $path, int $uid, int $gid): array
 	{
 		$_fileList = [];
 		$path = self::makeCorrectDir($path);
@@ -503,7 +484,8 @@ class FileDir
 			// Will exclude everything under these directories
 			$exclude = [
 				'awstats',
-				'webalizer'
+				'webalizer',
+				'goaccess'
 			];
 
 			/**
@@ -569,7 +551,7 @@ class FileDir
 	 *
 	 * @return string functionname + parameter (not the file)
 	 */
-	private static function getImmutableFunction(bool $remove = false)
+	private static function getImmutableFunction(bool $remove = false): string
 	{
 		if (self::isFreeBSD()) {
 			// FreeBSD style
@@ -589,7 +571,7 @@ class FileDir
 	 *
 	 * @return bool
 	 */
-	public static function isFreeBSD(bool $exact = false)
+	public static function isFreeBSD(bool $exact = false): bool
 	{
 		if (($exact && PHP_OS == 'FreeBSD') || (!$exact && stristr(PHP_OS, 'BSD'))) {
 			return true;
diff --git a/lib/Froxlor/Froxlor.php b/lib/Froxlor/Froxlor.php
index 553d2262..18d3b8ea 100644
--- a/lib/Froxlor/Froxlor.php
+++ b/lib/Froxlor/Froxlor.php
@@ -45,7 +45,7 @@ final class Froxlor
 	 *
 	 * @return string
 	 */
-	public static function getInstallDir()
+	public static function getInstallDir(): string
 	{
 		return dirname(__DIR__, 2) . '/';
 	}
@@ -55,7 +55,7 @@ final class Froxlor
 	 *
 	 * @return string
 	 */
-	public static function getVersion()
+	public static function getVersion(): string
 	{
 		return self::VERSION;
 	}
@@ -65,7 +65,7 @@ final class Froxlor
 	 *
 	 * @return string
 	 */
-	public static function getVersionString()
+	public static function getVersionString(): string
 	{
 		return self::getFullVersion() . ' (' . self::DBVERSION . ')';
 	}
@@ -75,7 +75,7 @@ final class Froxlor
 	 *
 	 * @return string
 	 */
-	public static function getFullVersion()
+	public static function getFullVersion(): string
 	{
 		return self::VERSION . self::BRANDING;
 	}
@@ -85,12 +85,11 @@ final class Froxlor
 	 *
 	 * checks if a given version is not equal the current one
 	 *
-	 * @param string $to_check
-	 *            version to check, if empty current version is used
+	 * @param string $to_check version to check, if empty current version is used
 	 *
 	 * @return bool true if version to check does not match, else false
 	 */
-	public static function hasUpdates($to_check = null)
+	public static function hasUpdates(string $to_check): bool
 	{
 		if (empty($to_check)) {
 			$to_check = self::VERSION;
@@ -102,16 +101,15 @@ final class Froxlor
 	}
 
 	/**
-	 * Function hasUpdates
+	 * Function hasDbUpdates
 	 *
 	 * checks if a given database-version is not equal the current one
 	 *
-	 * @param int $to_check
-	 *            version to check, if empty current dbversion is used
+	 * @param string $to_check version to check, if empty current dbversion is used
 	 *
 	 * @return bool true if version to check does not match, else false
 	 */
-	public static function hasDbUpdates($to_check = null)
+	public static function hasDbUpdates(string $to_check): bool
 	{
 		if (empty($to_check)) {
 			$to_check = self::DBVERSION;
@@ -127,12 +125,11 @@ final class Froxlor
 	 *
 	 * checks if a given database-version is the current one
 	 *
-	 * @param int $to_check
-	 *            version to check
+	 * @param string $to_check version to check
 	 *
 	 * @return bool true if version to check matches, else false
 	 */
-	public static function isDatabaseVersion($to_check = null)
+	public static function isDatabaseVersion(string $to_check): bool
 	{
 		if (Settings::Get('panel.frontend') == 'froxlor' && Settings::Get('panel.db_version') == $to_check) {
 			return true;
@@ -146,14 +143,14 @@ final class Froxlor
 	 * updates the panel.version field
 	 * to the given value (no checks here!)
 	 *
-	 * @param string $new_version
-	 *            new-version
+	 * @param string $new_version new-version
 	 *
 	 * @return bool true on success, else false
+	 * @throws \Exception
 	 */
-	public static function updateToDbVersion($new_version = null)
+	public static function updateToDbVersion(string $new_version): bool
 	{
-		if ($new_version !== null && $new_version != '') {
+		if ($new_version != '') {
 			$upd_stmt = Database::prepare("
 				UPDATE `" . TABLE_PANEL_SETTINGS . "` SET `value` = :newversion
 				WHERE `settinggroup` = 'panel' AND `varname` = 'db_version'");
@@ -172,14 +169,14 @@ final class Froxlor
 	 * updates the panel.version field
 	 * to the given value (no checks here!)
 	 *
-	 * @param string $new_version
-	 *            new-version
+	 * @param string $new_version new-version
 	 *
 	 * @return bool true on success, else false
+	 * @throws \Exception
 	 */
-	public static function updateToVersion($new_version = null)
+	public static function updateToVersion(string $new_version): bool
 	{
-		if ($new_version !== null && $new_version != '') {
+		if ($new_version != '') {
 			$upd_stmt = Database::prepare("
 				UPDATE `" . TABLE_PANEL_SETTINGS . "` SET `value` = :newversion
 				WHERE `settinggroup` = 'panel' AND `varname` = 'version'");
@@ -199,7 +196,7 @@ final class Froxlor
 	 *
 	 * @return bool true if panel is froxlor, else false
 	 */
-	public static function isFroxlor()
+	public static function isFroxlor(): bool
 	{
 		if (Settings::Get('panel.frontend') !== null && Settings::Get('panel.frontend') == 'froxlor') {
 			return true;
@@ -213,12 +210,11 @@ final class Froxlor
 	 * checks if a given version is the
 	 * current one (and panel is froxlor)
 	 *
-	 * @param string $to_check
-	 *            version to check
+	 * @param string $to_check version to check
 	 *
 	 * @return bool true if version to check matches, else false
 	 */
-	public static function isFroxlorVersion($to_check = null)
+	public static function isFroxlorVersion(string $to_check): bool
 	{
 		if (Settings::Get('panel.frontend') == 'froxlor' && Settings::Get('panel.version') == $to_check) {
 			return true;
@@ -231,10 +227,11 @@ final class Froxlor
 	 *
 	 * @param int $length
 	 * @return string
+	 * @throws \Exception
 	 */
-	public static function genSessionId(int $length = 16)
+	public static function genSessionId(int $length = 16): string
 	{
-		if (intval($length) <= 8) {
+		if ($length <= 8) {
 			$length = 16;
 		}
 		if (function_exists('random_bytes')) {
@@ -256,9 +253,9 @@ final class Froxlor
 	 * @param string $a
 	 * @param string $b
 	 *
-	 * @return integer 0 if equal, 1 if a>b and -1 if b>a
+	 * @return int 0 if equal, 1 if a>b and -1 if b>a
 	 */
-	public static function versionCompare2($a, $b)
+	public static function versionCompare2(string $a, string $b): int
 	{
 		// split version into pieces and remove trailing .0
 		$a = explode(".", $a);
@@ -295,7 +292,11 @@ final class Froxlor
 		return (count($a) < count($b)) ? -1 : 0;
 	}
 
-	private static function parseVersionArray(&$arr = null)
+	/**
+	 * @param array|null $arr
+	 * @return void
+	 */
+	private static function parseVersionArray(array &$arr = null)
 	{
 		// -dev or -beta or -rc ?
 		if (stripos($arr[count($arr) - 1], '-') !== false) {
@@ -306,16 +307,20 @@ final class Froxlor
 				$arr[] = '2'; // dev < beta < rc
 				// number of rc
 				$arr[] = substr($x[1], 2);
-			} else if (stripos($x[1], 'beta') !== false) {
-				$arr[] = '-1';
-				$arr[] = '1'; // dev < beta < rc
-				// number of beta
-				$arr[] = substr($x[1], 3);
-			} else if (stripos($x[1], 'dev') !== false) {
-				$arr[] = '-1';
-				$arr[] = '0'; // dev < beta < rc
-				// number of dev
-				$arr[] = substr($x[1], 3);
+			} else {
+				if (stripos($x[1], 'beta') !== false) {
+					$arr[] = '-1';
+					$arr[] = '1'; // dev < beta < rc
+					// number of beta
+					$arr[] = substr($x[1], 3);
+				} else {
+					if (stripos($x[1], 'dev') !== false) {
+						$arr[] = '-1';
+						$arr[] = '0'; // dev < beta < rc
+						// number of dev
+						$arr[] = substr($x[1], 3);
+					}
+				}
 			}
 		}
 	}
diff --git a/lib/Froxlor/FroxlorLogger.php b/lib/Froxlor/FroxlorLogger.php
index 4bbd5e09..014d84c4 100644
--- a/lib/Froxlor/FroxlorLogger.php
+++ b/lib/Froxlor/FroxlorLogger.php
@@ -45,38 +45,42 @@ class FroxlorLogger
 	/**
 	 * current \Monolog\Logger object
 	 *
-	 * @var Logger
+	 * @var ?Logger
 	 */
-	private static $ml = null;
+	private static ?Logger $ml = null;
 	/**
 	 * LogTypes Array
 	 *
-	 * @var array
+	 * @var ?array
 	 */
-	private static $logtypes = null;
+	private static ?array $logtypes = null;
 	/**
 	 * whether to output log-messages to STDOUT (cron)
 	 *
 	 * @var bool
 	 */
-	private static $crondebug_flag = false;
+	private static bool $crondebug_flag = false;
 	/**
-	 * user info of logged in user
+	 * user info of logged-in user
 	 *
 	 * @var array
 	 */
-	private static $userinfo = [];
+	private static array $userinfo = [];
 	/**
 	 * whether the logger object has already been initialized
 	 *
 	 * @var bool
 	 */
-	private static $is_initialized = false;
+	private static bool $is_initialized = false;
 
 	/**
 	 * Class constructor.
+	 *
+	 * @param array $userinfo
+	 *
+	 * @throws \Exception
 	 */
-	protected function __construct($userinfo = [])
+	protected function __construct(array $userinfo = [])
 	{
 		$this->initMonolog();
 		self::$userinfo = $userinfo;
@@ -143,8 +147,9 @@ class FroxlorLogger
 	 * @param array $userinfo
 	 *
 	 * @return FroxlorLogger
+	 * @throws \Exception
 	 */
-	public static function getInstanceOf($userinfo = [])
+	public static function getInstanceOf(array $userinfo = [])
 	{
 		if (empty($userinfo)) {
 			$userinfo = [
@@ -159,9 +164,9 @@ class FroxlorLogger
 	 *
 	 * @param int $action
 	 * @param int $type
-	 * @param string $text
+	 * @param ?string $text
 	 */
-	public function logAction($action = FroxlorLogger::USR_ACTION, $type = LOG_NOTICE, $text = null)
+	public function logAction($action = FroxlorLogger::USR_ACTION, int $type = LOG_NOTICE, string $text = null)
 	{
 		// not logging normal stuff if not set to "paranoid" logging
 		if (!self::$crondebug_flag && Settings::Get('logger.severity') == '1' && $type > LOG_NOTICE) {
@@ -208,7 +213,11 @@ class FroxlorLogger
 		}
 	}
 
-	public function getLogLevelDesc($type)
+	/**
+	 * @param int $type
+	 * @return string
+	 */
+	public function getLogLevelDesc(int $type): string
 	{
 		switch ($type) {
 			case LOG_INFO:
@@ -236,7 +245,11 @@ class FroxlorLogger
 		return $_type;
 	}
 
-	private function getActionTypeDesc($action)
+	/**
+	 * @param $action
+	 * @return string
+	 */
+	private function getActionTypeDesc($action): string
 	{
 		switch ($action) {
 			case FroxlorLogger::USR_ACTION:
@@ -268,7 +281,7 @@ class FroxlorLogger
 	 *
 	 * @return int
 	 */
-	public function setCronLog(int $cronlog = 0)
+	public function setCronLog(int $cronlog = 0): int
 	{
 		if ($cronlog < 0 || $cronlog > 2) {
 			$cronlog = 0;
diff --git a/lib/Froxlor/Http/Directory.php b/lib/Froxlor/Http/Directory.php
index 1777eae3..3070a47a 100644
--- a/lib/Froxlor/Http/Directory.php
+++ b/lib/Froxlor/Http/Directory.php
@@ -47,15 +47,17 @@ class Directory
 	 *
 	 * @param string $dir
 	 */
-	public function __construct($dir = null)
+	public function __construct(string $dir = null)
 	{
 		$this->dir = $dir;
 	}
 
 	/**
 	 * check whether the directory has options set in panel_htaccess
+	 *
+	 * @return bool
 	 */
-	public function hasUserOptions()
+	public function hasUserOptions(): bool
 	{
 		$uo_stmt = Database::prepare("
 			SELECT COUNT(`id`) as `usropts` FROM `" . TABLE_PANEL_HTACCESS . "` WHERE `path` = :dir
@@ -63,7 +65,7 @@ class Directory
 		$uo_res = Database::pexecute_first($uo_stmt, [
 			'dir' => FileDir::makeCorrectDir($this->dir)
 		]);
-		if ($uo_res != false && isset($uo_res['usropts'])) {
+		if ($uo_res && isset($uo_res['usropts'])) {
 			return $uo_res['usropts'] > 0;
 		}
 		return false;
@@ -71,8 +73,10 @@ class Directory
 
 	/**
 	 * check whether the directory is protected using panel_htpasswd
+	 *
+	 * @return bool
 	 */
-	public function isUserProtected()
+	public function isUserProtected(): bool
 	{
 		$up_stmt = Database::prepare("
 			SELECT COUNT(`id`) as `usrprot` FROM `" . TABLE_PANEL_HTPASSWDS . "` WHERE `path` = :dir
@@ -80,7 +84,7 @@ class Directory
 		$up_res = Database::pexecute_first($up_stmt, [
 			'dir' => FileDir::makeCorrectDir($this->dir)
 		]);
-		if ($up_res != false && isset($up_res['usrprot'])) {
+		if ($up_res && isset($up_res['usrprot'])) {
 			return $up_res['usrprot'] > 0;
 		}
 		return false;
@@ -90,12 +94,11 @@ class Directory
 	 * Checks if a given directory is valid for multiple configurations
 	 * or should rather be used as a single file
 	 *
-	 * @param bool $ifexists
-	 *            also check whether file/dir exists
+	 * @param bool $ifexists also check whether file/dir exists
 	 *
 	 * @return bool true if usable as dir, false otherwise
 	 */
-	public function isConfigDir($ifexists = false)
+	public function isConfigDir(bool $ifexists = false): bool
 	{
 		if (is_null($this->dir)) {
 			trigger_error(__CLASS__ . '::' . __FUNCTION__ . ' has been called with a null value', E_USER_WARNING);
diff --git a/lib/Froxlor/Http/HttpClient.php b/lib/Froxlor/Http/HttpClient.php
index f6a66c9d..f7c92373 100644
--- a/lib/Froxlor/Http/HttpClient.php
+++ b/lib/Froxlor/Http/HttpClient.php
@@ -33,6 +33,10 @@ class HttpClient
 	/**
 	 * Executes simple GET request
 	 *
+	 * @param string $url
+	 * @param bool $follow_location
+	 * @param int $timeout
+	 *
 	 * @return bool|string
 	 * @throws Exception
 	 */
@@ -59,6 +63,10 @@ class HttpClient
 	/**
 	 * Downloads and stores a file from an url
 	 *
+	 * @param string $url
+	 * @param string $target
+	 *
+	 * @return bool|string
 	 * @throws Exception
 	 */
 	public static function fileGet(string $url, string $target)
diff --git a/lib/Froxlor/Http/PhpConfig.php b/lib/Froxlor/Http/PhpConfig.php
index 0ff5bb26..91037413 100644
--- a/lib/Froxlor/Http/PhpConfig.php
+++ b/lib/Froxlor/Http/PhpConfig.php
@@ -37,7 +37,7 @@ class PhpConfig
 	 *
 	 * @return array
 	 */
-	public static function getPhpConfigs()
+	public static function getPhpConfigs(): array
 	{
 		$configs_array = [];
 
diff --git a/lib/Froxlor/Http/Statistics.php b/lib/Froxlor/Http/Statistics.php
index 33dacbf4..da19e7a1 100644
--- a/lib/Froxlor/Http/Statistics.php
+++ b/lib/Froxlor/Http/Statistics.php
@@ -36,16 +36,22 @@ class Statistics
 	 * Create or modify the AWStats configuration file for the given domain.
 	 * Modified by Berend Dekens to allow custom configurations.
 	 *
-	 * @param
-	 *            logFile
-	 * @param
-	 *            siteDomain
-	 * @param
-	 *            hostAliases
+	 * @param string $logFile
+	 * @param string $siteDomain
+	 * @param string $hostAliases
+	 * @param string $customerDocroot
+	 * @param array $domain_data
+	 *
 	 * @return null
+	 * @throws \Exception
 	 */
-	public static function createAWStatsConf($logFile, $siteDomain, $hostAliases, $customerDocroot, $awstats_params = [])
-	{
+	public static function createAWStatsConf(
+		string $logFile,
+		string $siteDomain,
+		string $hostAliases,
+		string $customerDocroot,
+		array $domain_data = []
+	) {
 		// Generation header
 		$header = "## GENERATED BY FROXLOR\n";
 		$header2 = "## Do not remove the line above! This tells Froxlor to update this configuration\n## If you wish to manually change this configuration file, remove the first line to make sure Froxlor won't rebuild this file\n## Generated for domain {SITE_DOMAIN} on " . date('l dS \of F Y h:i:s A') . "\n";
@@ -55,7 +61,7 @@ class Statistics
 			FileDir::safe_exec('mkdir -p ' . escapeshellarg($awstats_dir));
 		}
 		// chown created folder, #258
-		self::makeChownWithNewStats($awstats_params);
+		self::makeChownWithNewStats($domain_data);
 
 		// weird but could happen...
 		if (!is_dir(Settings::Get('system.awstats_conf'))) {
@@ -127,16 +133,15 @@ class Statistics
 	}
 
 	/**
-	 * chowns either awstats or webalizer folder,
-	 * either with webserver-user or - if fcgid
-	 * is used - the customers name, #258
+	 * chowns stats-tools folder, either with webserver-user or
+	 * if fcgid/php-fpm is used, the customers name, #258
 	 *
-	 * @param array $row
-	 *            array if panel_customers
+	 * @param array $row array of panel_customers
 	 *
 	 * @return void
+	 * @throws \Exception
 	 */
-	public static function makeChownWithNewStats($row)
+	public static function makeChownWithNewStats(array $row)
 	{
 		// get correct user
 		if ((Settings::Get('system.mod_fcgid') == '1' || Settings::Get('phpfpm.enabled') == '1') && isset($row['deactivated']) && $row['deactivated'] == '0') {
diff --git a/lib/Froxlor/Idna/IdnaWrapper.php b/lib/Froxlor/Idna/IdnaWrapper.php
index fb192b08..6ad750a0 100644
--- a/lib/Froxlor/Idna/IdnaWrapper.php
+++ b/lib/Froxlor/Idna/IdnaWrapper.php
@@ -54,16 +54,15 @@ class IdnaWrapper
 	}
 
 	/**
-	 * Encode a domain name, a email address or a list of one of both.
+	 * Encode a domain name, an email address or a list of one of both.
 	 *
-	 * @param
-	 *            string May be either a single domain name, e single email address or a list of one
+	 * @param string $to_encode May be either a single domain name, e single email address or a list of one
 	 *            separated either by ',', ';' or ' '.
 	 *
 	 * @return string Returns either a single domain name, a single email address or a list of one of
 	 *         both separated by the same string as the input.
 	 */
-	public function encode($to_encode)
+	public function encode(string $to_encode): string
 	{
 		$to_encode = $this->isUtf8($to_encode) ? $to_encode : utf8_encode($to_encode);
 		try {
@@ -83,7 +82,7 @@ class IdnaWrapper
 	 *
 	 * @return boolean
 	 */
-	private function isUtf8($string = null)
+	private function isUtf8(string $string)
 	{
 		if (function_exists("mb_detect_encoding")) {
 			if (mb_detect_encoding($string, 'UTF-8, ISO-8859-1') === 'UTF-8') {
@@ -119,16 +118,15 @@ class IdnaWrapper
 	}
 
 	/**
-	 * Decode a domain name, a email address or a list of one of both.
+	 * Decode a domain name, an email address or a list of one of both.
 	 *
-	 * @param
-	 *            string May be either a single domain name, e single email address or a list of one
+	 * @param string $to_decode May be either a single domain name, e single email address or a list of one
 	 *            separated either by ',', ';' or ' '.
 	 *
 	 * @return string Returns either a single domain name, a single email address or a list of one of
 	 *         both separated by the same string as the input.
 	 */
-	public function decode($to_decode)
+	public function decode(string $to_decode): string
 	{
 		return $this->idna_converter->decode($to_decode);
 	}
diff --git a/lib/Froxlor/PhpHelper.php b/lib/Froxlor/PhpHelper.php
index 75e7d7ac..33b1a685 100644
--- a/lib/Froxlor/PhpHelper.php
+++ b/lib/Froxlor/PhpHelper.php
@@ -43,9 +43,9 @@ class PhpHelper
 	 * @param array $list
 	 * @param string $key
 	 *
-	 * @return boolean
+	 * @return bool
 	 */
-	public static function sortListBy(&$list, $key = 'id')
+	public static function sortListBy(array &$list, string $key = 'id'): bool
 	{
 		self::$sort_type = Settings::Get('panel.natsorting') == 1 ? SORT_NATURAL : SORT_STRING;
 		self::$sort_key = $key;
@@ -59,14 +59,10 @@ class PhpHelper
 	 * Wrapper around htmlentities to handle arrays, with the advantage that you
 	 * can select which fields should be handled by htmlentities
 	 *
-	 * @param array|string $subject
-	 *            The subject array
-	 * @param string $fields
-	 *            The fields which should be checked for, separated by spaces
-	 * @param int $quote_style
-	 *            See php documentation about this
-	 * @param string $charset
-	 *            See php documentation about this
+	 * @param array|string $subject The subject array
+	 * @param array|string $fields The fields which should be checked for, separated by spaces
+	 * @param int $quote_style See php documentation about this
+	 * @param string $charset See php documentation about this
 	 *
 	 * @return array|string The string or an array with htmlentities converted strings
 	 * @author Florian Lippert <flo@syscp.org> (2003-2009)
@@ -79,7 +75,7 @@ class PhpHelper
 			}
 
 			foreach ($subject as $field => $value) {
-				if ((!is_array($fields) || empty($fields)) || (is_array($fields) && !empty($fields) && in_array($field, $fields))) {
+				if ((!is_array($fields) || empty($fields)) || (in_array($field, $fields))) {
 					// Just call ourselve to manage multi-dimensional arrays
 					$subject[$field] = self::htmlentitiesArray($value, $fields, $quote_style, $charset);
 				}
@@ -94,45 +90,36 @@ class PhpHelper
 	/**
 	 * Returns array with all empty-values removed
 	 *
-	 * @param array $source
-	 *            The array to trim
+	 * @param array $source The array to trim
 	 * @return array The trim'med array
 	 */
-	public static function arrayTrim($source)
+	public static function arrayTrim(array $source): array
 	{
-		$returnval = [];
-		if (is_array($source)) {
-			$source = array_map('trim', $source);
-			$returnval = array_filter($source, function ($value) {
-				return $value !== '';
-			});
-		} else {
-			$returnval = $source;
-		}
-		return $returnval;
+		$source = array_map('trim', $source);
+		return array_filter($source, function ($value) {
+			return $value !== '';
+		});
 	}
 
 	/**
 	 * Replaces Strings in an array, with the advantage that you
 	 * can select which fields should be str_replace'd
 	 *
-	 * @param string|array $search
-	 *                String or array of strings to search for
-	 * @param string|array $reaplce
-	 *                String or array to replace with
-	 * @param string|array $subject
-	 *                String or array The subject array
-	 * @param string $fields
-	 *                string The fields which should be checked for, separated by spaces
+	 * @param string|array $search String or array of strings to search for
+	 * @param string|array $replace String or array to replace with
+	 * @param string|array $subject String or array The subject array
+	 * @param string|array $fields string The fields which should be checked for, separated by spaces
+	 *
 	 * @return string|array The str_replace'd array
-	 * @author Florian Lippert <flo@syscp.org> (2003-2009)
 	 */
 	public static function strReplaceArray($search, $replace, $subject, $fields = '')
 	{
 		if (is_array($subject)) {
-			$fields = self::arrayTrim(explode(' ', $fields));
+			if (!is_array($fields)) {
+				$fields = self::arrayTrim(explode(' ', $fields));
+			}
 			foreach ($subject as $field => $value) {
-				if ((!is_array($fields) || empty($fields)) || (is_array($fields) && !empty($fields) && in_array($field, $fields))) {
+				if ((!is_array($fields) || empty($fields)) || (in_array($field, $fields))) {
 					$subject[$field] = str_replace($search, $replace, $value);
 				}
 			}
@@ -177,7 +164,8 @@ class PhpHelper
 			$err_display .= '<br><p><pre>';
 			$debug = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
 			foreach ($debug as $dline) {
-				$err_display .= $dline['function'] . '() called at [' . str_replace(Froxlor::getInstallDir(), '', ($dline['file'] ?? 'unknown')) . ':' . ($dline['line'] ?? 0) . ']<br>';
+				$err_display .= $dline['function'] . '() called at [' . str_replace(Froxlor::getInstallDir(), '',
+						($dline['file'] ?? 'unknown')) . ':' . ($dline['line'] ?? 0) . ']<br>';
 			}
 			$err_display .= '</pre></p>';
 			// end later
@@ -193,9 +181,13 @@ class PhpHelper
 		return false;
 	}
 
+	/**
+	 * @param Throwable $exception
+	 * @return void
+	 */
 	public static function phpExceptionHandler(Throwable $exception)
 	{
-		if (!isset($_SERVER['SHELL']) || (isset($_SERVER['SHELL']) && $_SERVER['SHELL'] == '')) {
+		if (!isset($_SERVER['SHELL']) || $_SERVER['SHELL'] == '') {
 			// show
 			UI::initTwig(true);
 			UI::twig()->addGlobal('install_mode', '1');
@@ -210,6 +202,10 @@ class PhpHelper
 		}
 	}
 
+	/**
+	 * @param ...$configdirs
+	 * @return array|null
+	 */
 	public static function loadConfigArrayDir(...$configdirs)
 	{
 		if (count($configdirs) <= 0) {
@@ -224,7 +220,8 @@ class PhpHelper
 			if (is_dir($data_dirname)) {
 				$data_dirhandle = opendir($data_dirname);
 				while (false !== ($data_filename = readdir($data_dirhandle))) {
-					if ($data_filename != '.' && $data_filename != '..' && $data_filename != '' && substr($data_filename, -4) == '.php') {
+					if ($data_filename != '.' && $data_filename != '..' && $data_filename != '' && substr($data_filename,
+							-4) == '.php') {
 						$data_files[] = $data_dirname . $data_filename;
 					}
 				}
@@ -248,7 +245,7 @@ class PhpHelper
 	 * @param string $host
 	 * @param boolean $try_a default true
 	 * @param string|null $nameserver set additional resolver nameserver to use (e.g. 1.1.1.1)
-	 * @return boolean|array
+	 * @return bool|array
 	 */
 	public static function gethostbynamel6(string $host, bool $try_a = true, string $nameserver = null)
 	{
@@ -315,7 +312,7 @@ class PhpHelper
 	 * @return string
 	 * @throws Exception
 	 */
-	public static function randomStr($length)
+	public static function randomStr(int $length): string
 	{
 		if (function_exists('openssl_random_pseudo_bytes')) {
 			return openssl_random_pseudo_bytes($length);
@@ -324,20 +321,21 @@ class PhpHelper
 	}
 
 	/**
-	 * Return human readable sizes
+	 * Return human-readable sizes
 	 *
-	 * @param int $size
-	 *            size in bytes
-	 * @param string $max
-	 *            maximum unit
-	 * @param string $system
-	 *            'si' for SI, 'bi' for binary prefixes
+	 * @param int $size size in bytes
+	 * @param string $max maximum unit
+	 * @param string $system 'si' for SI, 'bi' for binary prefixes
+	 * @param string $retstring string-format
 	 *
-	 * @param string $retstring
-	 *            string
+	 * @return string
 	 */
-	public static function sizeReadable($size, $max = null, $system = 'si', $retstring = '%01.2f %s')
-	{
+	public static function sizeReadable(
+		int $size,
+		string $max = '',
+		string $system = 'si',
+		string $retstring = '%01.2f %s'
+	): string {
 		// Pick units
 		$systems = [
 			'si' => [
@@ -363,7 +361,7 @@ class PhpHelper
 				'size' => 1024
 			]
 		];
-		$sys = isset($systems[$system]) ? $systems[$system] : $systems['si'];
+		$sys = $systems[$system] ?? $systems['si'];
 
 		// Max unit to display
 		$depth = count($sys['prefix']) - 1;
@@ -384,14 +382,12 @@ class PhpHelper
 	 * Replaces all occurrences of variables defined in the second argument
 	 * in the first argument with their values.
 	 *
-	 * @param string $text
-	 *            The string that should be searched for variables
-	 * @param array $vars
-	 *            The array containing the variables with their values
+	 * @param string $text The string that should be searched for variables
+	 * @param array $vars The array containing the variables with their values
 	 *
 	 * @return string The submitted string with the variables replaced.
 	 */
-	public static function replaceVariables($text, $vars)
+	public static function replaceVariables(string $text, array $vars): string
 	{
 		$pattern = "/\{([a-zA-Z0-9\-_]+)\}/";
 		$matches = [];
@@ -407,12 +403,22 @@ class PhpHelper
 			}
 		}
 
-		$text = str_replace('\n', "\n", $text);
-		return $text;
+		return str_replace('\n', "\n", $text);
 	}
 
-	public static function recursive_array_search($needle, $haystack, &$keys = [], $currentKey = '')
-	{
+	/**
+	 * @param string $needle
+	 * @param array $haystack
+	 * @param array $keys
+	 * @param string $currentKey
+	 * @return true
+	 */
+	public static function recursive_array_search(
+		string $needle,
+		array $haystack,
+		array &$keys = [],
+		string $currentKey = ''
+	): bool {
 		foreach ($haystack as $key => $value) {
 			$pathkey = empty($currentKey) ? $key : $currentKey . '.' . $key;
 			if (is_array($value)) {
@@ -427,13 +433,13 @@ class PhpHelper
 	}
 
 	/**
-	 * function to check a super-global passed by reference
+	 * function to check a super-global passed by reference,
 	 * so it gets automatically updated
 	 *
 	 * @param array $global
 	 * @param AntiXSS $antiXss
 	 */
-	public static function cleanGlobal(&$global, &$antiXss)
+	public static function cleanGlobal(array &$global, AntiXSS &$antiXss)
 	{
 		$ignored_fields = [
 			'system_default_vhostconf',
@@ -455,7 +461,12 @@ class PhpHelper
 		}
 	}
 
-	private static function sortListByGivenKey($a, $b): int
+	/**
+	 * @param array $a
+	 * @param array $b
+	 * @return int
+	 */
+	private static function sortListByGivenKey(array $a, array $b): int
 	{
 		if (self::$sort_type == SORT_NATURAL) {
 			return strnatcasecmp($a[self::$sort_key], $b[self::$sort_key]);
@@ -488,35 +499,33 @@ class PhpHelper
 	/**
 	 * Parse array to array string.
 	 *
-	 * @param $array
-	 * @param $key
+	 * @param array $array
+	 * @param ?string $key
 	 * @param int $depth
 	 * @return string
 	 */
-	public static function parseArrayToString($array, $key = null, int $depth = 1): string
+	public static function parseArrayToString(array $array, string $key = null, int $depth = 1): string
 	{
 		$str = '';
-		if (is_array($array)) {
-			if (!is_null($key)) {
-				$str .= self::tabPrefix(($depth-1), "'{$key}' => [\n");
-			} else {
-				$str .= self::tabPrefix(($depth-1), "[\n");
-			}
-			foreach ($array as $key => $value) {
-				if (!is_array($value)) {
-					if (is_bool($value)) {
-						$str .= self::tabPrefix($depth, sprintf("'%s' => %s,\n", $key, $value ? 'true' : 'false'));
-					} elseif (is_int($value)) {
-						$str .= self::tabPrefix($depth, "'{$key}' => $value,\n");
-					} else {
-						$str .= self::tabPrefix($depth, "'{$key}' => '{$value}',\n");
-					}
-				} elseif (is_array($value)) {
-					$str .= self::parseArrayToString($value, $key, ($depth + 1));
-				}
-			}
-			$str .= self::tabPrefix(($depth-1), "],\n");
+		if (!is_null($key)) {
+			$str .= self::tabPrefix(($depth - 1), "'{$key}' => [\n");
+		} else {
+			$str .= self::tabPrefix(($depth - 1), "[\n");
 		}
+		foreach ($array as $key => $value) {
+			if (!is_array($value)) {
+				if (is_bool($value)) {
+					$str .= self::tabPrefix($depth, sprintf("'%s' => %s,\n", $key, $value ? 'true' : 'false'));
+				} elseif (is_int($value)) {
+					$str .= self::tabPrefix($depth, "'{$key}' => $value,\n");
+				} else {
+					$str .= self::tabPrefix($depth, "'{$key}' => '{$value}',\n");
+				}
+			} else {
+				$str .= self::parseArrayToString($value, $key, ($depth + 1));
+			}
+		}
+		$str .= self::tabPrefix(($depth - 1), "],\n");
 		return $str;
 	}
 
diff --git a/lib/Froxlor/Settings/FroxlorVhostSettings.php b/lib/Froxlor/Settings/FroxlorVhostSettings.php
index 10a7629f..171f5fcb 100644
--- a/lib/Froxlor/Settings/FroxlorVhostSettings.php
+++ b/lib/Froxlor/Settings/FroxlorVhostSettings.php
@@ -30,10 +30,19 @@ use Froxlor\Database\Database;
 class FroxlorVhostSettings
 {
 
-	public static function hasVhostContainerEnabled($need_ssl = false)
+	/**
+	 * @param bool $need_ssl
+	 *
+	 * @return bool
+	 * @throws \Exception
+	 */
+	public static function hasVhostContainerEnabled(bool $need_ssl = false): bool
 	{
 		$sel_stmt = Database::prepare("SELECT COUNT(*) as vcentries FROM `" . TABLE_PANEL_IPSANDPORTS . "` WHERE `vhostcontainer`= '1'" . ($need_ssl ? " AND `ssl` = '1'" : ""));
 		$result = Database::pexecute_first($sel_stmt);
-		return $result['vcentries'] > 0;
+		if ($result) {
+			return $result['vcentries'] > 0;
+		}
+		return false;
 	}
 }
diff --git a/lib/Froxlor/System/Cronjob.php b/lib/Froxlor/System/Cronjob.php
index 43642442..84c7d337 100644
--- a/lib/Froxlor/System/Cronjob.php
+++ b/lib/Froxlor/System/Cronjob.php
@@ -100,32 +100,34 @@ class Cronjob
 
 					// now check if it differs from our settings
 					if ($update_to_guid != Settings::Get('system.lastguid')) {
-						$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE, 'Updating froxlor last guid to ' . $update_to_guid);
+						$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE,
+							'Updating froxlor last guid to ' . $update_to_guid);
 						Settings::Set('system.lastguid', $update_to_guid);
 					}
 				} else {
-					$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE, 'File /etc/group not readable; cannot check for latest guid');
+					$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE,
+						'File /etc/group not readable; cannot check for latest guid');
 				}
 			} else {
-				$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE, 'File /etc/group not readable; cannot check for latest guid');
+				$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE,
+					'File /etc/group not readable; cannot check for latest guid');
 			}
 		} else {
-			$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE, 'File /etc/group does not exist; cannot check for latest guid');
+			$mylog->logAction(FroxlorLogger::CRON_ACTION, LOG_NOTICE,
+				'File /etc/group does not exist; cannot check for latest guid');
 		}
 	}
 
 	/**
 	 * Inserts a task into the PANEL_TASKS-Table
 	 *
-	 * @param
-	 *            int Type of task
-	 * @param
-	 *            string Parameter (possible to pass multiple times)
+	 * @param int $type Type of task
+	 * @param string $params Parameter (possible to pass multiple times)
 	 *
-	 * @author Florian Lippert <flo@syscp.org> (2003-2009)
+	 * @throws Exception
 	 * @author Froxlor team <team@froxlor.org> (2010-)
 	 */
-	public static function inserttask($type, ...$params)
+	public static function inserttask(int $type, ...$params)
 	{
 		// prepare the insert-statement
 		$ins_stmt = Database::prepare("
@@ -223,7 +225,7 @@ class Cronjob
 	 *
 	 * @return array
 	 */
-	public static function getCronjobsLastRun()
+	public static function getCronjobsLastRun(): array
 	{
 		$query = "SELECT `lastrun`, `desc_lng_key` FROM `" . TABLE_PANEL_CRONRUNS . "` WHERE `isactive` = '1' ORDER BY `cronfile` ASC";
 		$result = Database::query($query);
@@ -238,14 +240,21 @@ class Cronjob
 		return $cronjobs_last_run;
 	}
 
-	public static function toggleCronStatus($module = null, $isactive = 0)
+	/**
+	 * @param string $module
+	 * @param int $isactive
+	 * @return void
+	 * @throws Exception
+	 */
+	public static function toggleCronStatus(string $module, int $isactive = 0)
 	{
 		if ($isactive != 1) {
 			$isactive = 0;
 		}
 
 		$upd_stmt = Database::prepare("
-		UPDATE `" . TABLE_PANEL_CRONRUNS . "` SET `isactive` = :active WHERE `module` = :module");
+			UPDATE `" . TABLE_PANEL_CRONRUNS . "` SET `isactive` = :active WHERE `module` = :module
+		");
 		Database::pexecute($upd_stmt, [
 			'active' => $isactive,
 			'module' => $module
@@ -257,7 +266,7 @@ class Cronjob
 	 *
 	 * @return array
 	 */
-	public static function getOutstandingTasks()
+	public static function getOutstandingTasks(): array
 	{
 		$query = "SELECT * FROM `" . TABLE_PANEL_TASKS . "` ORDER BY `type` ASC";
 		$result = Database::query($query);
@@ -309,7 +318,7 @@ class Cronjob
 	 *
 	 * @return void
 	 */
-	public static function dieWithMail($message, $subject = "[froxlor] Cronjob error")
+	public static function dieWithMail(string $message, string $subject = "[froxlor] Cronjob error")
 	{
 		if (Settings::Get('system.send_cron_errors') == '1') {
 			$_mail = new Mailer(true);
@@ -339,7 +348,12 @@ class Cronjob
 		die($message);
 	}
 
-	public static function updateLastRunOfCron($cronname)
+	/**
+	 * @param string $cronname
+	 * @return void
+	 * @throws Exception
+	 */
+	public static function updateLastRunOfCron(string $cronname)
 	{
 		$upd_stmt = Database::prepare("
 			UPDATE `" . TABLE_PANEL_CRONRUNS . "` SET `lastrun` = UNIX_TIMESTAMP() WHERE `cronfile` = :cron;
diff --git a/lib/Froxlor/System/Crypt.php b/lib/Froxlor/System/Crypt.php
index 425656a8..35c030de 100644
--- a/lib/Froxlor/System/Crypt.php
+++ b/lib/Froxlor/System/Crypt.php
@@ -41,7 +41,7 @@ class Crypt
 	 *
 	 * @return string
 	 */
-	public static function generatePassword(int $length = 0, bool $isSalt = false)
+	public static function generatePassword(int $length = 0, bool $isSalt = false): string
 	{
 		$alpha_lower = 'abcdefghijklmnopqrstuvwxyz';
 		$alpha_upper = strtoupper($alpha_lower);
@@ -78,7 +78,7 @@ class Crypt
 	 *
 	 * @return string
 	 */
-	private static function specialShuffle($str = null)
+	private static function specialShuffle(string $str): string
 	{
 		$len = mb_strlen($str);
 		$sploded = [];
@@ -94,7 +94,7 @@ class Crypt
 	 *
 	 * @return array
 	 */
-	public static function getAvailablePasswordHashes()
+	public static function getAvailablePasswordHashes(): array
 	{
 		// get available pwd-hases
 		$available_pwdhashes = [
@@ -120,31 +120,40 @@ class Crypt
 	 * we check against the length, if not matched
 	 * an error message will be output and 'exit' is called
 	 *
-	 * @param string $password
-	 *            the password to validate
+	 * @param string $password the password to validate
+	 * @param bool $json_response
 	 *
 	 * @return string either the password or an errormessage+exit
 	 */
-	public static function validatePassword($password = null, $json_response = false)
+	public static function validatePassword(string $password, bool $json_response = false): string
 	{
 		if (Settings::Get('panel.password_min_length') > 0) {
-			$password = Validate::validate($password, Settings::Get('panel.password_min_length'), '/^.{' . (int)Settings::Get('panel.password_min_length') . ',}$/D', 'notrequiredpasswordlength', [], $json_response);
+			$password = Validate::validate($password, Settings::Get('panel.password_min_length'),
+				'/^.{' . (int)Settings::Get('panel.password_min_length') . ',}$/D', 'notrequiredpasswordlength', [],
+				$json_response);
 		}
 
 		if (Settings::Get('panel.password_regex') != '') {
-			$password = Validate::validate($password, Settings::Get('panel.password_regex'), Settings::Get('panel.password_regex'), 'notrequiredpasswordcomplexity', [], $json_response);
+			$password = Validate::validate($password, Settings::Get('panel.password_regex'),
+				Settings::Get('panel.password_regex'), 'notrequiredpasswordcomplexity', [], $json_response);
 		} else {
 			if (Settings::Get('panel.password_alpha_lower')) {
-				$password = Validate::validate($password, '/.*[a-z]+.*/', '/.*[a-z]+.*/', 'notrequiredpasswordcomplexity', [], $json_response);
+				$password = Validate::validate($password, '/.*[a-z]+.*/', '/.*[a-z]+.*/',
+					'notrequiredpasswordcomplexity', [], $json_response);
 			}
 			if (Settings::Get('panel.password_alpha_upper')) {
-				$password = Validate::validate($password, '/.*[A-Z]+.*/', '/.*[A-Z]+.*/', 'notrequiredpasswordcomplexity', [], $json_response);
+				$password = Validate::validate($password, '/.*[A-Z]+.*/', '/.*[A-Z]+.*/',
+					'notrequiredpasswordcomplexity', [], $json_response);
 			}
 			if (Settings::Get('panel.password_numeric')) {
-				$password = Validate::validate($password, '/.*[0-9]+.*/', '/.*[0-9]+.*/', 'notrequiredpasswordcomplexity', [], $json_response);
+				$password = Validate::validate($password, '/.*[0-9]+.*/', '/.*[0-9]+.*/',
+					'notrequiredpasswordcomplexity', [], $json_response);
 			}
 			if (Settings::Get('panel.password_special_char_required')) {
-				$password = Validate::validate($password, '/.*[' . preg_quote(Settings::Get('panel.password_special_char'), '/') . ']+.*/', '/.*[' . preg_quote(Settings::Get('panel.password_special_char'), '/') . ']+.*/', 'notrequiredpasswordcomplexity', [], $json_response);
+				$password = Validate::validate($password,
+					'/.*[' . preg_quote(Settings::Get('panel.password_special_char'), '/') . ']+.*/',
+					'/.*[' . preg_quote(Settings::Get('panel.password_special_char'), '/') . ']+.*/',
+					'notrequiredpasswordcomplexity', [], $json_response);
 			}
 		}
 
@@ -159,19 +168,20 @@ class Crypt
 	 * additionally it updates the hash if the system settings changed
 	 * or if the very old md5() sum is used
 	 *
-	 * @param array $userinfo
-	 *            user-data from table
-	 * @param string $password
-	 *            the password to validate
-	 * @param string $table
-	 *            either panel_customers or panel_admins
-	 * @param string $uid
-	 *            user-id-field in $table
+	 * @param array $userinfo user-data from table
+	 * @param string $password the password to validate
+	 * @param string $table either panel_customers or panel_admins
+	 * @param string $uid user-id-field in $table
 	 *
-	 * @return boolean
+	 * @return bool
+	 * @throws \Exception
 	 */
-	public static function validatePasswordLogin($userinfo = null, $password = null, $table = 'panel_customers', $uid = 'customerid')
-	{
+	public static function validatePasswordLogin(
+		array $userinfo,
+		string $password,
+		string $table = 'panel_customers',
+		string $uid = 'customerid'
+	): bool {
 		$algo = Settings::Get('system.passwordcryptfunc') !== null ? Settings::Get('system.passwordcryptfunc') : PASSWORD_DEFAULT;
 		if (is_numeric($algo)) {
 			// old setting format
@@ -209,16 +219,13 @@ class Crypt
 	/**
 	 * Make encrypted password from clear text password
 	 *
-	 * @param string $password
-	 *            Password to be encrypted
-	 * @param bool $htpasswd
-	 *            optional whether to generate a SHA1 password for directory protection
-	 * @param bool $ftpd
-	 *            optional generates sha256 password strings for proftpd/pureftpd
+	 * @param string $password Password to be encrypted
+	 * @param bool $htpasswd optional whether to generate a SHA1 password for directory protection
+	 * @param bool $ftpd optional generates sha256 password strings for proftpd/pureftpd
 	 *
 	 * @return string encrypted password
 	 */
-	public static function makeCryptPassword(string $password, bool $htpasswd = false, bool $ftpd = false)
+	public static function makeCryptPassword(string $password, bool $htpasswd = false, bool $ftpd = false): string
 	{
 		if ($htpasswd || $ftpd) {
 			if ($ftpd) {
diff --git a/lib/Froxlor/System/IPTools.php b/lib/Froxlor/System/IPTools.php
index 03d8a4d6..3cea8ee0 100644
--- a/lib/Froxlor/System/IPTools.php
+++ b/lib/Froxlor/System/IPTools.php
@@ -36,7 +36,7 @@ class IPTools
 	 *
 	 * @return string
 	 */
-	public static function cidr2NetmaskAddr($cidr)
+	public static function cidr2NetmaskAddr(string $cidr): string
 	{
 		$ta = substr($cidr, strpos($cidr, '/') + 1) * 1;
 		$netmask = str_split(str_pad(str_pad('', $ta, '1'), 32, '0'), 8);
@@ -52,7 +52,7 @@ class IPTools
 	 * Checks whether the given $ip is in range of given ip/cidr range
 	 *
 	 * @param array $ip_cidr 0 => ip, 1 => netmask in decimal, e.g. [0 => '123.123.123.123', 1 => 24]
-	 * @param string $ip     ip-address to check
+	 * @param string $ip ip-address to check
 	 *
 	 * @return bool
 	 */
@@ -77,7 +77,7 @@ class IPTools
 	 *
 	 * @return string|bool ip address on success, false on failure
 	 */
-	public static function is_ipv6($address)
+	public static function is_ipv6(string $address)
 	{
 		return filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6);
 	}
@@ -86,7 +86,7 @@ class IPTools
 	 * Checks whether the given ipv6 $ip is in range of given ip/cidr range
 	 *
 	 * @param array $ip_cidr 0 => ip, 1 => netmask in decimal, e.g. [0 => '123:123::1', 1 => 64]
-	 * @param string $ip     ip-address to check
+	 * @param string $ip ip-address to check
 	 *
 	 * @return bool
 	 */
@@ -130,6 +130,10 @@ class IPTools
 		return $in_range;
 	}
 
+	/**
+	 * @param string $addr
+	 * @return false|string
+	 */
 	private static function inet6_expand(string $addr)
 	{
 		// Check if there are segments missing, insert if necessary
@@ -139,7 +143,7 @@ class IPTools
 			$part[1] = explode(':', $part[1]);
 			$missing = [];
 			for ($i = 0; $i < (8 - (count($part[0]) + count($part[1]))); $i++) {
-				array_push($missing, '0000');
+				$missing[] = '0000';
 			}
 			$missing = array_merge($part[0], $missing);
 			$part = array_merge($missing, $part[1]);
@@ -163,17 +167,18 @@ class IPTools
 		}
 	}
 
-	private static function inet6_prefix_to_mask($prefix)
+	/**
+	 * @param int $prefix
+	 * @return false|string
+	 */
+	private static function inet6_prefix_to_mask(int $prefix)
 	{
 		/* Make sure the prefix is a number between 1 and 127 (inclusive) */
-		$prefix = intval($prefix);
 		if ($prefix < 0 || $prefix > 128) {
 			return false;
 		}
 		$mask = '0b';
-		for ($i = 0; $i < $prefix; $i++) {
-			$mask .= '1';
-		}
+		$mask .= str_repeat('1', $prefix);
 		for ($i = strlen($mask) - 2; $i < 128; $i++) {
 			$mask .= '0';
 		}
@@ -188,7 +193,11 @@ class IPTools
 		return inet_ntop(inet_pton($result));
 	}
 
-	private static function ip2long6($ip)
+	/**
+	 * @param string $ip
+	 * @return string
+	 */
+	private static function ip2long6(string $ip): string
 	{
 		$ip_n = inet_pton($ip);
 		$bits = 15; // 16 x 8 bit = 128bit
diff --git a/lib/Froxlor/System/Mailer.php b/lib/Froxlor/System/Mailer.php
index a3b965c4..b8b11cc8 100644
--- a/lib/Froxlor/System/Mailer.php
+++ b/lib/Froxlor/System/Mailer.php
@@ -26,6 +26,7 @@
 namespace Froxlor\System;
 
 use Froxlor\Settings;
+use PHPMailer\PHPMailer\Exception;
 use PHPMailer\PHPMailer\PHPMailer;
 
 class Mailer extends PHPMailer
@@ -34,9 +35,9 @@ class Mailer extends PHPMailer
 	/**
 	 * class constructor
 	 *
-	 * @param bool $exceptions
-	 *            whether to throw exceptions or not
+	 * @param bool $exceptions whether to throw exceptions or not
 	 *
+	 * @throws Exception
 	 */
 	public function __construct(bool $exceptions = false)
 	{
diff --git a/lib/Froxlor/System/MysqlHandler.php b/lib/Froxlor/System/MysqlHandler.php
index c5067b4d..85987c60 100644
--- a/lib/Froxlor/System/MysqlHandler.php
+++ b/lib/Froxlor/System/MysqlHandler.php
@@ -32,7 +32,7 @@ use Monolog\Logger;
 class MysqlHandler extends AbstractProcessingHandler
 {
 
-	protected static $froxlorLevels = [
+	protected static array $froxlorLevels = [
 		Logger::DEBUG => LOG_DEBUG,
 		Logger::INFO => LOG_INFO,
 		Logger::NOTICE => LOG_NOTICE,
@@ -47,11 +47,10 @@ class MysqlHandler extends AbstractProcessingHandler
 	/**
 	 * Constructor
 	 *
-	 * @param bool|int $level
-	 *            Debug level which this handler should store
+	 * @param bool|int $level Debug level which this handler should store
 	 * @param bool $bubble
 	 */
-	public function __construct($level = Logger::DEBUG, $bubble = true)
+	public function __construct($level = Logger::DEBUG, bool $bubble = true)
 	{
 		parent::__construct($level, $bubble);
 	}
@@ -66,8 +65,8 @@ class MysqlHandler extends AbstractProcessingHandler
 	{
 		$this->insert([
 			':message' => $record['message'],
-			':contextUser' => (isset($record['context']['user']) ? $record['context']['user'] : 'unknown'),
-			':contextAction' => (isset($record['context']['action']) ? $record['context']['action'] : '0'),
+			':contextUser' => ($record['context']['user'] ?? 'unknown'),
+			':contextAction' => ($record['context']['action'] ?? '0'),
 			':level' => self::$froxlorLevels[$record['level']],
 			':datetime' => $record['datetime']->format('U')
 		]);
@@ -79,7 +78,7 @@ class MysqlHandler extends AbstractProcessingHandler
 	 * @param array $data
 	 * @return bool
 	 */
-	protected function insert(array $data)
+	protected function insert(array $data): bool
 	{
 		if ($this->pdoStatement === null) {
 			$sql = "INSERT INTO `panel_syslog` SET `text` = :message, `user` = :contextUser, `action` = :contextAction, `type` = :level, `date` = :datetime";
diff --git a/lib/Froxlor/Traffic/Traffic.php b/lib/Froxlor/Traffic/Traffic.php
index e992334b..2b14b654 100644
--- a/lib/Froxlor/Traffic/Traffic.php
+++ b/lib/Froxlor/Traffic/Traffic.php
@@ -32,9 +32,16 @@ use Froxlor\Api\Commands\Traffic as TrafficAPI;
 
 class Traffic
 {
-	public static function getCustomerStats($userinfo, $range = null): array
+	/**
+	 * @param array $userinfo
+	 * @param ?string $range
+	 * @return array
+	 * @throws \Exception
+	 */
+	public static function getCustomerStats(array $userinfo, string $range = null): array
 	{
-		$trafficCollectionObj = (new Collection(TrafficAPI::class, $userinfo, self::getParamsByRange($range, ['customer_traffic' => true,])));
+		$trafficCollectionObj = (new Collection(TrafficAPI::class, $userinfo,
+			self::getParamsByRange($range, ['customer_traffic' => true,])));
 		if ($userinfo['adminsession'] == 1) {
 			$trafficCollectionObj->has('customer', Customers::class, 'customerid', 'customerid');
 		}
@@ -58,15 +65,15 @@ class Traffic
 			$years[$item['year']]['ftp'] += ($item['ftp_up'] + $item['ftp_down']);
 			$years[$item['year']]['mail'] += $item['mail'];
 			// per month
-			$months[$item['month'].'/'.$item['year']]['total'] += ($item['http'] + $item['ftp_up'] + $item['ftp_down'] + $item['mail']);
-			$months[$item['month'].'/'.$item['year']]['http'] += $item['http'];
-			$months[$item['month'].'/'.$item['year']]['ftp'] += ($item['ftp_up'] + $item['ftp_down']);
-			$months[$item['month'].'/'.$item['year']]['mail'] += $item['mail'];
+			$months[$item['month'] . '/' . $item['year']]['total'] += ($item['http'] + $item['ftp_up'] + $item['ftp_down'] + $item['mail']);
+			$months[$item['month'] . '/' . $item['year']]['http'] += $item['http'];
+			$months[$item['month'] . '/' . $item['year']]['ftp'] += ($item['ftp_up'] + $item['ftp_down']);
+			$months[$item['month'] . '/' . $item['year']]['mail'] += $item['mail'];
 			// per day
-			$days[$item['day'].'.'.$item['month'].'.'.$item['year']]['total'] += ($item['http'] + $item['ftp_up'] + $item['ftp_down'] + $item['mail']);
-			$days[$item['day'].'.'.$item['month'].'.'.$item['year']]['http'] += $item['http'];
-			$days[$item['day'].'.'.$item['month'].'.'.$item['year']]['ftp'] += ($item['ftp_up'] + $item['ftp_down']);
-			$days[$item['day'].'.'.$item['month'].'.'.$item['year']]['mail'] += $item['mail'];
+			$days[$item['day'] . '.' . $item['month'] . '.' . $item['year']]['total'] += ($item['http'] + $item['ftp_up'] + $item['ftp_down'] + $item['mail']);
+			$days[$item['day'] . '.' . $item['month'] . '.' . $item['year']]['http'] += $item['http'];
+			$days[$item['day'] . '.' . $item['month'] . '.' . $item['year']]['ftp'] += ($item['ftp_up'] + $item['ftp_down']);
+			$days[$item['day'] . '.' . $item['month'] . '.' . $item['year']]['mail'] += $item['mail'];
 		}
 
 		// calculate overview for given range from users
@@ -94,7 +101,13 @@ class Traffic
 		];
 	}
 
-	private static function getParamsByRange($range = null, array $params = [])
+	/**
+	 * @param ?string $range
+	 * @param array $params
+	 * @return array
+	 * @throws \Exception
+	 */
+	private static function getParamsByRange(string $range = null, array $params = []): array
 	{
 		$dateParams = [];
 
diff --git a/lib/Froxlor/Validate/Check.php b/lib/Froxlor/Validate/Check.php
index 2c487da5..d59defd7 100644
--- a/lib/Froxlor/Validate/Check.php
+++ b/lib/Froxlor/Validate/Check.php
@@ -38,6 +38,13 @@ class Check
 
 	const FORMFIELDS_PLAUSIBILITY_CHECK_QUESTION = 2;
 
+	/**
+	 * @param $fieldname
+	 * @param $fielddata
+	 * @param $newfieldvalue
+	 * @param $allnewfieldvalues
+	 * @return array|int[]
+	 */
 	public static function checkFcgidPhpFpm($fieldname, $fielddata, $newfieldvalue, $allnewfieldvalues)
 	{
 		$returnvalue = [
@@ -76,7 +83,8 @@ class Check
 				} else {
 					// fcgid is being validated before fpm -> "ask" fpm about its state
 					if ($fieldname == 'system_mod_fcgid_enabled') {
-						$returnvalue = self::checkFcgidPhpFpm('system_phpfpm_enabled', null, $check_array[$fieldname]['other_post_field'], null);
+						$returnvalue = self::checkFcgidPhpFpm('system_phpfpm_enabled', null,
+							$check_array[$fieldname]['other_post_field'], null);
 					} else {
 						// not, bot are nogo
 						$returnvalue = $returnvalue = [
@@ -109,7 +117,8 @@ class Check
 		$mysql_access_host_array = array_unique(array_map('trim', explode(',', $newfieldvalue)));
 
 		foreach ($mysql_access_host_array as $host_entry) {
-			if (Validate::validate_ip2($host_entry, true, 'invalidip', true, true, true, true, false) == false && Validate::validateDomain($host_entry) == false && Validate::validateLocalHostname($host_entry) == false && $host_entry != '%') {
+			if (Validate::validate_ip2($host_entry, true, 'invalidip', true, true, true, true,
+					false) == false && Validate::validateDomain($host_entry) == false && Validate::validateLocalHostname($host_entry) == false && $host_entry != '%') {
 				return [
 					self::FORMFIELDS_PLAUSIBILITY_CHECK_ERROR,
 					'invalidmysqlhost',
@@ -123,6 +132,13 @@ class Check
 		];
 	}
 
+	/**
+	 * @param $fieldname
+	 * @param $fielddata
+	 * @param $newfieldvalue
+	 * @param $allnewfieldvalues
+	 * @return array|int[]
+	 */
 	public static function checkHostname($fieldname, $fielddata, $newfieldvalue, $allnewfieldvalues)
 	{
 		if (0 == strlen(trim($newfieldvalue)) || Validate::validateDomain($newfieldvalue) === false) {
@@ -141,10 +157,12 @@ class Check
 	 * check whether an email account is to be deleted
 	 * reference: #1519
 	 *
-	 * @return bool true if the domain is to be deleted, false otherwise
+	 * @param string $email_addr
 	 *
+	 * @return bool true if the domain is to be deleted, false otherwise
+	 * @throws \Exception
 	 */
-	public static function checkMailAccDeletionState($email_addr = null)
+	public static function checkMailAccDeletionState(string $email_addr): bool
 	{
 		// example data of task 7: a:2:{s:9:"loginname";s:4:"webX";s:5:"email";s:20:"deleteme@example.tld";}
 
@@ -164,6 +182,14 @@ class Check
 		return false;
 	}
 
+	/**
+	 * @param $fieldname
+	 * @param $fielddata
+	 * @param $newfieldvalue
+	 * @param $allnewfieldvalues
+	 * @return array|int[]
+	 * @throws \Exception
+	 */
 	public static function checkPathConflicts($fieldname, $fielddata, $newfieldvalue, $allnewfieldvalues)
 	{
 		if ((int)Settings::Get('system.mod_fcgid') == 1) {
@@ -178,7 +204,8 @@ class Check
 			}
 
 			// neither dir can be within the other nor can they be equal
-			if (substr($newdir, 0, strlen($cdir)) == $cdir || substr($cdir, 0, strlen($newdir)) == $newdir || $newdir == $cdir) {
+			if (substr($newdir, 0, strlen($cdir)) == $cdir || substr($cdir, 0,
+					strlen($newdir)) == $newdir || $newdir == $cdir) {
 				$returnvalue = [
 					self::FORMFIELDS_PLAUSIBILITY_CHECK_ERROR,
 					'fcgidpathcannotbeincustomerdoc'
@@ -197,6 +224,13 @@ class Check
 		return $returnvalue;
 	}
 
+	/**
+	 * @param $fieldname
+	 * @param $fielddata
+	 * @param $newfieldvalue
+	 * @param $allnewfieldvalues
+	 * @return array|int[]
+	 */
 	public static function checkPhpInterfaceSetting($fieldname, $fielddata, $newfieldvalue, $allnewfieldvalues)
 	{
 		$returnvalue = [
@@ -216,6 +250,13 @@ class Check
 		return $returnvalue;
 	}
 
+	/**
+	 * @param $fieldname
+	 * @param $fielddata
+	 * @param $newfieldvalue
+	 * @param $allnewfieldvalues
+	 * @return array|int[]
+	 */
 	public static function checkUsername($fieldname, $fielddata, $newfieldvalue, $allnewfieldvalues)
 	{
 		if (!isset($allnewfieldvalues['customer_mysqlprefix'])) {
@@ -223,7 +264,8 @@ class Check
 		}
 
 		$returnvalue = [];
-		if (Validate::validateUsername($newfieldvalue, Settings::Get('panel.unix_names'), Database::getSqlUsernameLength() - strlen($allnewfieldvalues['customer_mysqlprefix'])) === true) {
+		if (Validate::validateUsername($newfieldvalue, Settings::Get('panel.unix_names'),
+				Database::getSqlUsernameLength() - strlen($allnewfieldvalues['customer_mysqlprefix'])) === true) {
 			$returnvalue = [
 				self::FORMFIELDS_PLAUSIBILITY_CHECK_OK
 			];
@@ -240,6 +282,13 @@ class Check
 		return $returnvalue;
 	}
 
+	/**
+	 * @param $fieldname
+	 * @param $fielddata
+	 * @param $newfieldvalue
+	 * @param $allnewfieldvalues
+	 * @return array|int[]
+	 */
 	public static function checkLocalGroup($fieldname, $fielddata, $newfieldvalue, $allnewfieldvalues)
 	{
 		if (empty($newfieldvalue) || $fielddata == $newfieldvalue) {
diff --git a/lib/Froxlor/Validate/Form.php b/lib/Froxlor/Validate/Form.php
index 804e05b3..dfa463ce 100644
--- a/lib/Froxlor/Validate/Form.php
+++ b/lib/Froxlor/Validate/Form.php
@@ -28,32 +28,40 @@ namespace Froxlor\Validate;
 class Form
 {
 
-	public static function validateFormDefinition($form)
+	/**
+	 * @param array $form
+	 * @return bool
+	 */
+	public static function validateFormDefinition(array $form): bool
 	{
-		$returnvalue = false;
-
-		if (is_array($form) && !empty($form) && isset($form['groups']) && is_array($form['groups']) && !empty($form['groups'])) {
-			$returnvalue = true;
+		if (!empty($form) && isset($form['groups']) && is_array($form['groups']) && !empty($form['groups'])) {
+			return true;
 		}
-
-		return $returnvalue;
+		return false;
 	}
 
-	public static function validateFieldDefinition($field)
+	/**
+	 * @param array $field
+	 * @return bool
+	 */
+	public static function validateFieldDefinition(array $field): bool
 	{
-		$returnvalue = false;
-
-		if (is_array($field) && !empty($field) && isset($field['fields']) && is_array($field['fields']) && !empty($field['fields'])) {
-			$returnvalue = true;
+		if (!empty($field) && isset($field['fields']) && is_array($field['fields']) && !empty($field['fields'])) {
+			return true;
 		}
-
-		return $returnvalue;
+		return false;
 	}
 
-	public static function validateFormField($fieldname, $fielddata, $newfieldvalue)
+	/**
+	 * @param $fieldname
+	 * @param array $fielddata
+	 * @param $newfieldvalue
+	 * @return mixed|string
+	 */
+	public static function validateFormField($fieldname, array $fielddata, $newfieldvalue)
 	{
 		$returnvalue = '';
-		if (is_array($fielddata) && isset($fielddata['type']) && $fielddata['type'] != '' && method_exists('\\Froxlor\\Validate\\Form\\Data', 'validateFormField' . ucfirst($fielddata['type']))) {
+		if (isset($fielddata['type']) && $fielddata['type'] != '' && method_exists('\\Froxlor\\Validate\\Form\\Data', 'validateFormField' . ucfirst($fielddata['type']))) {
 			$returnvalue = call_user_func([
 				'\\Froxlor\\Validate\\Form\\Data',
 				'validateFormField' . ucfirst($fielddata['type'])
diff --git a/lib/Froxlor/Validate/Validate.php b/lib/Froxlor/Validate/Validate.php
index 99d544ad..8332c7eb 100644
--- a/lib/Froxlor/Validate/Validate.php
+++ b/lib/Froxlor/Validate/Validate.php
@@ -57,9 +57,16 @@ class Validate
 	 * @param bool $throw_exception whether to display error or throw an exception, default false
 	 *
 	 * @return string|void the clean string or error
+	 * @throws Exception
 	 */
-	public static function validate($str, string $fieldname, string $pattern = '', $lng = '', $emptydefault = [], bool $throw_exception = false)
-	{
+	public static function validate(
+		string $str,
+		string $fieldname,
+		string $pattern = '',
+		$lng = '',
+		$emptydefault = [],
+		bool $throw_exception = false
+	) {
 		if (!is_array($emptydefault)) {
 			$emptydefault_array = [
 				$emptydefault
@@ -101,27 +108,28 @@ class Validate
 	/**
 	 * Checks whether it is a valid ip
 	 *
-	 * @param string $ip
-	 *            ip-address to check
-	 * @param bool $return_bool
-	 *            whether to return bool or call \Froxlor\UI\Response::standard_error()
-	 * @param string $lng
-	 *            index for error-message (if $return_bool is false)
-	 * @param bool $allow_localhost
-	 *            whether to allow 127.0.0.1
-	 * @param bool $allow_priv
-	 *            whether to allow private network addresses
-	 * @param bool $allow_cidr
-	 *            whether to allow CIDR values e.g. 10.10.10.10/16
-	 * @param bool $cidr_as_netmask
-	 *            whether to format CIDR nodation to netmask notation
-	 * @param bool $throw_exception
-	 *            whether to throw an exception on failure
+	 * @param string $ip ip-address to check
+	 * @param bool $return_bool whether to return bool or call \Froxlor\UI\Response::standard_error()
+	 * @param string $lng index for error-message (if $return_bool is false)
+	 * @param bool $allow_localhost whether to allow 127.0.0.1
+	 * @param bool $allow_priv whether to allow private network addresses
+	 * @param bool $allow_cidr whether to allow CIDR values e.g. 10.10.10.10/16
+	 * @param bool $cidr_as_netmask whether to format CIDR notation to netmask notation
+	 * @param bool $throw_exception whether to throw an exception on failure
 	 *
 	 * @return string|bool|void ip address on success, false on failure (or nothing if error is displayed)
+	 * @throws Exception
 	 */
-	public static function validate_ip2($ip, bool $return_bool = false, string $lng = 'invalidip', bool $allow_localhost = false, bool $allow_priv = false, bool $allow_cidr = false, bool $cidr_as_netmask = false, bool $throw_exception = false)
-	{
+	public static function validate_ip2(
+		string $ip,
+		bool $return_bool = false,
+		string $lng = 'invalidip',
+		bool $allow_localhost = false,
+		bool $allow_priv = false,
+		bool $allow_cidr = false,
+		bool $cidr_as_netmask = false,
+		bool $throw_exception = false
+	) {
 		$cidr = "";
 		if ($allow_cidr) {
 			$org_ip = $ip;
@@ -131,7 +139,8 @@ class Validate
 				if (IPTools::is_ipv6($ip_cidr[0])) {
 					$cidr_range_max = 128;
 				}
-				if (strlen($ip_cidr[1]) <= 3 && in_array((int)$ip_cidr[1], array_values(range(1, $cidr_range_max)), true) === false) {
+				if (strlen($ip_cidr[1]) <= 3 && in_array((int)$ip_cidr[1], array_values(range(1, $cidr_range_max)),
+						true) === false) {
 					if ($return_bool) {
 						return false;
 					}
@@ -161,7 +170,8 @@ class Validate
 
 		$filter_lan = $allow_priv ? FILTER_FLAG_NO_RES_RANGE : (FILTER_FLAG_NO_RES_RANGE | FILTER_FLAG_NO_PRIV_RANGE);
 
-		if ((filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) || filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) && filter_var($ip, FILTER_VALIDATE_IP, $filter_lan)) {
+		if ((filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) || filter_var($ip, FILTER_VALIDATE_IP,
+					FILTER_FLAG_IPV4)) && filter_var($ip, FILTER_VALIDATE_IP, $filter_lan)) {
 			return $ip . $cidr;
 		}
 
@@ -179,14 +189,12 @@ class Validate
 	/**
 	 * Returns whether a URL is in a correct format or not
 	 *
-	 * @param string $url
-	 *            URL to be tested
-	 * @param bool $allow_private_ip
-	 *          optional, default is false
+	 * @param string $url URL to be tested
+	 * @param bool $allow_private_ip optional, default is false
 	 *
 	 * @return bool
 	 */
-	public static function validateUrl(string $url, bool $allow_private_ip = false)
+	public static function validateUrl(string $url, bool $allow_private_ip = false): bool
 	{
 		if (strtolower(substr($url, 0, 7)) != "http://" && strtolower(substr($url, 0, 8)) != "https://") {
 			$url = 'http://' . $url;
@@ -215,25 +223,22 @@ class Validate
 	/**
 	 * Check if the submitted string is a valid domainname
 	 *
-	 * @param string $domainname
-	 *            The domainname which should be checked.
-	 * @param bool $allow_underscore
-	 *            optional if true, allowes the underscore character in a domain label (DKIM etc.)
+	 * @param string $domainname The domainname which should be checked.
+	 * @param bool $allow_underscore optional if true, allowes the underscore character in a domain label (DKIM etc.)
 	 *
 	 * @return string|boolean the domain-name if the domain is valid, false otherwise
 	 */
-	public static function validateDomain($domainname, $allow_underscore = false)
+	public static function validateDomain(string $domainname, bool $allow_underscore = false)
 	{
-		if (is_string($domainname)) {
-			$char_validation = '([a-z\d](-*[a-z\d])*)(\.?([a-z\d](-*[a-z\d])*))*\.(xn\-\-)?([a-z\d])+';
-			if ($allow_underscore) {
-				$char_validation = '([a-z\d\_](-*[a-z\d\_])*)(\.([a-z\d\_](-*[a-z\d])*))*(\.?([a-z\d](-*[a-z\d])*))+\.(xn\-\-)?([a-z\d])+';
-			}
+		$char_validation = '([a-z\d](-*[a-z\d])*)(\.?([a-z\d](-*[a-z\d])*))*\.(xn\-\-)?([a-z\d])+';
+		if ($allow_underscore) {
+			$char_validation = '([a-z\d\_](-*[a-z\d\_])*)(\.([a-z\d\_](-*[a-z\d])*))*(\.?([a-z\d](-*[a-z\d])*))+\.(xn\-\-)?([a-z\d])+';
+		}
 
-			// valid chars check && overall length check && length of each label
-			if (preg_match("/^" . $char_validation . "$/i", $domainname) && preg_match("/^.{1,253}$/", $domainname) && preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $domainname)) {
-				return $domainname;
-			}
+		// valid chars check && overall length check && length of each label
+		if (preg_match("/^" . $char_validation . "$/i", $domainname) && preg_match("/^.{1,253}$/",
+				$domainname) && preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $domainname)) {
+			return $domainname;
 		}
 		return false;
 	}
@@ -245,7 +250,7 @@ class Validate
 	 *
 	 * @return string|boolean hostname on success, else false
 	 */
-	public static function validateLocalHostname($hostname)
+	public static function validateLocalHostname(string $hostname)
 	{
 		$pattern = '/^[a-z0-9][a-z0-9\-]{0,62}$/i';
 		if (preg_match($pattern, $hostname)) {
@@ -257,11 +262,11 @@ class Validate
 	/**
 	 * Returns if an emailaddress is in correct format or not
 	 *
-	 * @param string $email
-	 *            The email address to check
-	 * @return bool Correct or not
+	 * @param string $email The email address to check
+	 *
+	 * @return mixed
 	 */
-	public static function validateEmail($email)
+	public static function validateEmail(string $email)
 	{
 		$email = strtolower($email);
 		// as of php-7.1
@@ -272,25 +277,22 @@ class Validate
 	}
 
 	/**
-	 * Returns if an username is in correct format or not.
+	 * Returns if a username is in correct format or not.
 	 *
-	 * @param string $username
-	 *            The username to check
-	 * @param bool $unix_names
-	 *            optional, default true, checks whether it must be UNIX compatible
-	 * @param int $mysql_max
-	 *            optional, number of max mysql username characters, default empty
+	 * @param string $username The username to check
+	 * @param bool $unix_names optional, default true, checks whether it must be UNIX compatible
+	 * @param int $mysql_max optional, number of max mysql username characters, default empty
 	 *
 	 * @return bool
 	 */
-	public static function validateUsername($username, $unix_names = 1, $mysql_max = '')
+	public static function validateUsername(string $username, bool $unix_names = true, int $mysql_max = 0): bool
 	{
-		if (empty($mysql_max) || !is_numeric($mysql_max) || $mysql_max <= 0) {
+		if (empty($mysql_max) || $mysql_max <= 0) {
 			$mysql_max = Database::getSqlUsernameLength() - 1;
 		} else {
 			$mysql_max--;
 		}
-		if ($unix_names == 0) {
+		if (!$unix_names) {
 			if (strpos($username, '--') === false) {
 				return (preg_match('/^[a-z][a-z0-9\-_]{0,' . $mysql_max . '}[a-z0-9]{1}$/Di', $username) != false);
 			}
@@ -304,9 +306,9 @@ class Validate
 	 *
 	 * @param string $interval
 	 *
-	 * @return boolean
+	 * @return bool
 	 */
-	public static function validateSqlInterval($interval = null)
+	public static function validateSqlInterval(string $interval): bool
 	{
 		if (!empty($interval) && strstr($interval, ' ') !== false) {
 			/*
@@ -325,7 +327,8 @@ class Validate
 
 			$interval_parts = explode(' ', $interval);
 
-			if (count($interval_parts) == 2 && preg_match('/[0-9]+/', $interval_parts[0]) && in_array(strtoupper($interval_parts[1]), $valid_expr)) {
+			if (count($interval_parts) == 2 && preg_match('/[0-9]+/',
+					$interval_parts[0]) && in_array(strtoupper($interval_parts[1]), $valid_expr)) {
 				return true;
 			}
 		}