* rewrite the hole script:

** use .env file for config so we can retrieve updates
** add config and payload DTO with validators
** allow registrable domains as DynDNS
** update IPv4/6 only if changed (or really forced)
** remove obsolete failed_logins counter
** save logs with timestamp
** save only the newest 100 log entries for each domain

src/Config.php

@@ -0,0 +1,122 @@
+<?php
+
+namespace netcup\DNS\API;
+
+final class Config
+{
+
+    /**
+     * @var string
+     */
+    private $username;
+
+    /**
+     * @var string
+     */
+    private $password;
+
+    /**
+     * @var string
+     */
+    private $apiKey;
+
+    /**
+     * @var string
+     */
+    private $apiPassword;
+
+    /**
+     * @var int
+     */
+    private $customerId;
+
+    /**
+     * @var string
+     */
+    private $logFile;
+
+    /**
+     * @var bool
+     */
+    private $debug;
+
+    public function __construct(array $config)
+    {
+        foreach (get_object_vars($this) as $key => $val) {
+            if (isset($config[$key])) {
+                $this->$key = $config[$key];
+            }
+        }
+    }
+
+    /**
+     * @return bool
+     */
+    public function isValid()
+    {
+        return
+            !empty($this->username) &&
+            !empty($this->password) &&
+            !empty($this->apiKey) &&
+            !empty($this->apiPassword) &&
+            !empty($this->customerId) &&
+            !empty($this->logFile);
+
+    }
+
+    /**
+     * @return string
+     */
+    public function getUsername()
+    {
+        return $this->username;
+    }
+
+    /**
+     * @return string
+     */
+    public function getPassword()
+    {
+        return $this->password;
+    }
+
+    /**
+     * @return string
+     */
+    public function getApiKey()
+    {
+        return $this->apiKey;
+    }
+
+    /**
+     * @return string
+     */
+    public function getApiPassword()
+    {
+        return $this->apiPassword;
+    }
+
+    /**
+     * @return int
+     */
+    public function getCustomerId()
+    {
+        return $this->customerId;
+    }
+
+    /**
+     * @return string
+     */
+    public function getLogFile()
+    {
+        return $this->logFile;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isDebug()
+    {
+        return $this->debug;
+    }
+}