* 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;
+    }
+}

src/Handler.php

@@ -0,0 +1,181 @@
+<?php
+
+namespace netcup\DNS\API;
+
+use RuntimeException;
+
+final class Handler
+{
+    /**
+     * @var array
+     */
+    private $log;
+
+    /**
+     * @var Config
+     */
+    private $config;
+
+    /**
+     * @var Payload
+     */
+    private $payload;
+
+    public function __construct(array $config, array $payload)
+    {
+        $this->config = new Config($config);
+
+        if (!$this->config->isValid()) {
+            throw new RuntimeException('configuration invalid');
+        }
+
+        $this->payload = new Payload($payload);
+
+        if (!$this->payload->isValid()) {
+            throw new RuntimeException('payload invalid');
+        }
+
+        if (
+            $this->config->getUsername() !== $this->payload->getUser() ||
+            $this->config->getPassword() !== $this->payload->getPassword()
+        ) {
+            throw new RuntimeException('credentials wrong');
+        }
+
+        if (is_readable($this->config->getLogFile())) {
+            $this->log = json_decode(file_get_contents($this->config->getLogFile()), true);
+        } else {
+            $this->log[$this->payload->getDomain()] = [];
+        }
+    }
+
+    public function __destruct()
+    {
+        $this->doExit();
+    }
+
+    /**
+     * @param string $msg
+     *
+     * @return self
+     */
+    private function doLog($msg)
+    {
+        $this->log[$this->payload->getDomain()][] = sprintf('[%s] %s', date('c'), $msg);
+
+        if ($this->config->isDebug()) {
+            printf('[DEBUG] %s %s', $msg, PHP_EOL);
+        }
+
+        return $this;
+    }
+
+    private function doExit()
+    {
+        // save only the newest 100 log entries for each domain
+        $this->log[$this->payload->getDomain()] = array_reverse(array_slice(array_reverse($this->log[$this->payload->getDomain()]), 0, 100));
+
+        if (!is_writable($this->config->getLogFile()) || !file_put_contents($this->config->getLogFile(), json_encode($this->log, JSON_PRETTY_PRINT))) {
+            printf('[ERROR] unable to write %s %s', $this->config->getLogFile(), PHP_EOL);
+        }
+    }
+
+    /**
+     *
+     * @return self
+     */
+    public function doRun()
+    {
+        $clientRequestId = md5($this->payload->getDomain() . time());
+
+        $dnsClient = new Soap\DomainWebserviceSoapClient();
+
+        $loginHandle = $dnsClient->login(
+            $this->config->getCustomerId(),
+            $this->config->getApiKey(),
+            $this->config->getApiPassword(),
+            $clientRequestId
+        );
+
+        if (2000 === $loginHandle->statuscode) {
+            $this->doLog('api login successful');
+        } else {
+            $this->doLog(sprintf('api login failed, message: %s', $loginHandle->longmessage));
+        }
+
+        $infoHandle = $dnsClient->infoDnsRecords(
+            $this->payload->getHostname(),
+            $this->config->getCustomerId(),
+            $this->config->getApiKey(),
+            $loginHandle->responsedata->apisessionid,
+            $clientRequestId
+        );
+
+
+        $changes = false;
+
+        foreach ($infoHandle->responsedata->dnsrecords as $key => $record) {
+            $recordHostnameReal = ($record->hostname !== '@') ? $record->hostname . '.' . $this->payload->getHostname() : $this->payload->getHostname();
+
+            if ($recordHostnameReal === $this->payload->getDomain()) {
+
+                // update A Record if exists and IP has changed
+                if ('A' === $record->type && $this->payload->getIpv4() &&
+                    (
+                        $this->payload->isForce() ||
+                        $record->destination !== $this->payload->getIpv4()
+                    )
+                ) {
+                    $record->destination = $this->payload->getIpv4();
+                    $this->doLog(sprintf('IPv4 for %s set to %s', $recordHostnameReal, $this->payload->getIpv4()));
+                    $changes = true;
+                }
+
+                // update AAAA Record if exists and IP has changed
+                if ('AAAA' === $record->type && $this->payload->getIpv6() &&
+                    (
+                        $this->payload->isForce()
+                        || $record->destination !== $this->payload->getIpv6()
+                    )
+                ) {
+                    $record->destination = $this->payload->getIpv6();
+                    $this->doLog(sprintf('IPv6 for %s set to %s', $recordHostnameReal, $this->payload->getIpv6()));
+                    $changes = true;
+                }
+            }
+        }
+
+        if (true === $changes) {
+            $recordSet = new Soap\Dnsrecordset();
+            $recordSet->dnsrecords = $infoHandle->responsedata->dnsrecords;
+
+            $dnsClient->updateDnsRecords(
+                $this->payload->getHostname(),
+                $this->config->getCustomerId(),
+                $this->config->getApiKey(),
+                $loginHandle->responsedata->apisessionid,
+                $clientRequestId,
+                $recordSet
+            );
+
+            $this->doLog('dns recordset updated');
+        } else {
+            $this->doLog('dns recordset NOT updated (no changes)');
+        }
+
+        $logoutHandle = $dnsClient->logout(
+            $this->config->getCustomerId(),
+            $this->config->getApiKey(),
+            $loginHandle->responsedata->apisessionid,
+            $clientRequestId
+        );
+
+        if (2000 === $logoutHandle->statuscode) {
+            $this->doLog('api logout successful');
+        } else {
+            $this->doLog(sprintf('api logout failed, message: %s', $loginHandle->longmessage));
+        }
+
+        return $this;
+    }
+}

src/Payload.php

@@ -0,0 +1,156 @@
+<?php
+
+namespace netcup\DNS\API;
+
+final class Payload
+{
+    /**
+     * @var string
+     */
+    private $user;
+
+    /**
+     * @var string
+     */
+    private $password;
+
+    /**
+     * @var string
+     */
+    private $domain;
+
+    /**
+     * @var string
+     */
+    private $ipv4;
+
+    /**
+     * @var string
+     */
+    private $ipv6;
+
+    /**
+     * @var bool
+     */
+    private $force = false;
+
+    public function __construct(array $payload)
+    {
+        foreach (get_object_vars($this) as $key => $val) {
+            if (isset($payload[$key])) {
+                $this->$key = $payload[$key];
+            }
+        }
+    }
+
+    /**
+     * @return bool
+     */
+    public function isValid()
+    {
+        return
+            !empty($this->user) &&
+            !empty($this->password) &&
+            !empty($this->domain) &&
+            (
+                (
+                    !empty($this->ipv4) && $this->isValidIpv4()
+                )
+                ||
+                (
+                    !empty($this->ipv6) && $this->isValidIpv6()
+                )
+            );
+    }
+
+    /**
+     * @return string
+     */
+    public function getUser()
+    {
+        return $this->user;
+    }
+
+    /**
+     * @return string
+     */
+    public function getPassword()
+    {
+        return $this->password;
+    }
+
+    /**
+     * @return string
+     */
+    public function getDomain()
+    {
+        return $this->domain;
+    }
+
+    /**
+     * there is no good way to get the correct "registrable" Domain without external libs!
+     *
+     * @see https://github.com/jeremykendall/php-domain-parser
+     *
+     * this method is still tricky, because:
+     *
+     * works: nas.tld.com
+     * works: nas.tld.de
+     * works: tld.com
+     * failed: nas.tld.co.uk
+     * failed: nas.home.tld.de
+     *
+     * @return string
+     */
+    public function getHostname()
+    {
+        // hack if top level domain are used for dynDNS
+        if (1 === substr_count($this->domain, '.')) {
+            return $this->domain;
+        }
+
+        $domainParts = explode('.', $this->domain);
+        array_shift($domainParts); // remove sub domain
+        return implode('.', $domainParts);
+    }
+
+    /**
+     * @return string
+     */
+    public function getIpv4()
+    {
+        return $this->ipv4;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isValidIpv4()
+    {
+        return (bool)filter_var($this->ipv4, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);
+    }
+
+    /**
+     * @return string
+     */
+    public function getIpv6()
+    {
+        return $this->ipv6;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isValidIpv6()
+    {
+        return (bool)filter_var($this->ipv6, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6);
+    }
+
+    /**
+     * @return bool
+     */
+    public function isForce()
+    {
+        return $this->force;
+    }
+}