some big beautiful update

application/Espo/Core/Utils/Security/HostCheck.php

@@ -0,0 +1,75 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM – Open Source CRM application.
+ * Copyright (C) 2014-2026 EspoCRM, Inc.
+ * Website: https://www.espocrm.com
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU Affero General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU Affero General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Utils\Security;
+
+use const DNS_A;
+use const FILTER_FLAG_NO_PRIV_RANGE;
+use const FILTER_FLAG_NO_RES_RANGE;
+use const FILTER_VALIDATE_IP;
+
+class HostCheck
+{
+    public function isNotInternalHost(string $host): bool
+    {
+        $records = dns_get_record($host, DNS_A);
+
+        if (filter_var($host, FILTER_VALIDATE_IP)) {
+            return $this->ipAddressIsNotInternal($host);
+        }
+
+        if (!$records) {
+            return true;
+        }
+
+        foreach ($records as $record) {
+            /** @var ?string $idAddress */
+            $idAddress = $record['ip'] ?? null;
+
+            if (!$idAddress) {
+                return false;
+            }
+
+            if (!$this->ipAddressIsNotInternal($idAddress)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private function ipAddressIsNotInternal(string $ipAddress): bool
+    {
+        return (bool) filter_var(
+            $ipAddress,
+            FILTER_VALIDATE_IP,
+            FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE
+        );
+    }
+}