diff --git a/lib/functions.php b/lib/functions.php
index 486ceea..96cb7e3 100644
--- a/lib/functions.php
+++ b/lib/functions.php
@@ -1,170 +1,157 @@
 <?php
-    /*****************************************************************************
-    IP Reg, a PHP/MySQL IPAM tool
-    Copyright (C) 2007-2009 Wietse Warendorff
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU 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 General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-    For more information, visit http://sourceforge.net/projects/ipreg,
-    or contact me at wietsew@users.sourceforge.net
-    *****************************************************************************/
+/*****************************************************************************
+IP Reg, a PHP/MySQL IPAM tool
+Copyright (C) 2007-2009 Wietse Warendorff (up to v0.5)
+Copyright (C) 2011-2023 Thomas Hooge
+
+SPDX-License-Identifier: GPL-3.0-or-later
+*****************************************************************************/
+
+// strip mac address to 12 char string
+function strip_mac($mac) {
+    // strip chars we don't need
+    $mac = preg_replace("|[^a-fA-F0-9]|", "", $mac);
+
+    // capitalize (just because it looks better eh)
+    $mac = strtoupper($mac);
+
+    // and return
+    return ($mac);
+}
+
+// rebuild mac address
+function write_mac($mac) {
+    // check string length
+    if (strlen($mac)!=12) {
+        // if the MAC is empty, or for whatever reason incorrect, just return
+        return $mac;
+    } else {
+        // count to 12...
+        for ($i=0; $i<12; $i++) {
+            // ... and strip mac to pieces
+            ${"mac".$i} = $mac{$i};
+        }
 
-    // strip mac address to 12 char string
-    function strip_mac($mac) {
-        // strip chars we don't need
-        $mac = preg_replace("|[^a-fA-F0-9]|", "", $mac);
+        // get user preference
+        $user_mac = $_SESSION['suser_mac'];
 
-        // capitalize (just because it looks better eh)
-        $mac = strtoupper($mac);
+        // count to 12 again...
+        for($i=0; $i<12; $i++) {
+            // ... and replace user preference with pieces
+            $user_mac = preg_replace("/x/", ${"mac".$i}, $user_mac, 1);
+        }
 
         // and return
-        return ($mac);
+        return $user_mac;
     }
+}
 
-    // rebuild mac address
-    function write_mac($mac) {
-        // check string length
-        if (strlen($mac)!=12) {
-            // if the MAC is empty, or for whatever reason incorrect, just return
-            return $mac;
-        } else {
-            // count to 12...
-            for($i=0;$i<12;$i++) {
-                // ... and strip mac to pieces
-                ${"mac".$i} = $mac{$i};
-            }
+// redirect page
+function header_location($location) {
+    // send header
+    header("location: " . $location);
 
-            // get user preference
-            $user_mac = $_SESSION['suser_mac'];
+    // exit to be sure
+    exit;
+}
 
-            // count to 12 again...
-            for($i=0;$i<12;$i++) {
-                // ... and replace user preference with pieces
-                $user_mac = preg_replace("/x/", ${"mac".$i}, $user_mac, 1);
-            }
+// sanitize input
+function sanitize($input) {
+    global $dblink;
 
-            // and return
-            return $user_mac;
-        }
-    }
+    // trim whitespaces
+    $input = @trim($input);
 
-    // redirect page
-    function header_location($location) {
-        // send header
-        header("location: " . $location);
-
-        // exit to be sure
-        exit;
+    // magic quotes enabled?
+    if(get_magic_quotes_gpc()) {
+        // strip slashes
+        $input = stripslashes($input);
     }
 
-    // sanitize input
-    function sanitize($input) {
-        global $dblink;
-
-        // trim whitespaces
-        $input = @trim($input);
+    // convert to utf-8
+    iconv("UTF-8", "UTF-8", $input);
 
-        // magic quotes enabled?
-        if(get_magic_quotes_gpc()) {
-            // strip slashes
-            $input = stripslashes($input);
-        }
-
-        // convert to utf-8
-        iconv("UTF-8", "UTF-8", $input);
+    // convert special chars
+    $input = htmlentities($input,ENT_QUOTES,'UTF-8');
 
-        // convert special chars
-        $input = htmlentities($input,ENT_QUOTES,'UTF-8');
+    // make sql ready
+    $input = mysqli_real_escape_string($dblink, $input);
 
-        // make sql ready
-        $input = mysqli_real_escape_string($dblink, $input);
+    // and return
+    return $input;
+}
 
-        // and return
+function mysql_nullstring($input) {
+    if (isset($input)) {
         return $input;
+    } else {
+        return '';
     }
+}
 
-    function mysql_nullstring($input) {
-        if (isset($input)) {
-            return $input;
-        } else {
-            return '';
-        }
+function lang_getfrombrowser ($allowed_languages, $default_language, $lang_variable = null, $strict_mode = true) {
+    if ($lang_variable === null) {
+        $lang_variable = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
     }
-
-    function lang_getfrombrowser ($allowed_languages, $default_language, $lang_variable = null, $strict_mode = true) {
-        if ($lang_variable === null) {
-            $lang_variable = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
+    if (empty($lang_variable)) {
+        return $default_language;
+    }
+    $accepted_languages = preg_split('/,\s*/', $lang_variable);
+    $current_lang = $default_language;
+    $current_q = 0;
+    foreach ($accepted_languages as $accepted_language) {
+        $res = preg_match ('/^([a-z]{1,8}(?:-[a-z]{1,8})*)(?:;\s*q=(0(?:\.[0-9]{1,3})?|1(?:\.0{1,3})?))?$/i',
+                   $accepted_language, $matches);
+        if (!$res) {
+            continue;
         }
-        if (empty($lang_variable)) {
-            return $default_language;
+        $lang_code = explode ('-', $matches[1]);
+        if (isset($matches[2])) {
+            $lang_quality = (float)$matches[2];
+        } else {
+            $lang_quality = 1.0;
         }
-        $accepted_languages = preg_split('/,\s*/', $lang_variable);
-        $current_lang = $default_language;
-        $current_q = 0;
-        foreach ($accepted_languages as $accepted_language) {
-            $res = preg_match ('/^([a-z]{1,8}(?:-[a-z]{1,8})*)(?:;\s*q=(0(?:\.[0-9]{1,3})?|1(?:\.0{1,3})?))?$/i',
-                       $accepted_language, $matches);
-            if (!$res) {
-                continue;
-            }
-            $lang_code = explode ('-', $matches[1]);
-            if (isset($matches[2])) {
-                $lang_quality = (float)$matches[2];
-            } else {
-                $lang_quality = 1.0;
-            }
-            while (count ($lang_code)) {
-                if (in_array (strtolower (join ('-', $lang_code)), $allowed_languages)) {
-                    if ($lang_quality > $current_q) {
-                        $current_lang = strtolower (join ('-', $lang_code));
-                        $current_q = $lang_quality;
-                        break;
-                    }
-                }
-                if ($strict_mode) {
+        while (count ($lang_code)) {
+            if (in_array (strtolower (join ('-', $lang_code)), $allowed_languages)) {
+                if ($lang_quality > $current_q) {
+                    $current_lang = strtolower (join ('-', $lang_code));
+                    $current_q = $lang_quality;
                     break;
                 }
-                array_pop ($lang_code);
             }
-        }
-        return $current_lang;
-    }
-
-    function print_tree_rec($tree, $level) {
-        $output = '<ul class="treelvl' . $level. '">' . "\n";
-        foreach ($tree as $node) {
-            $output .= '<li><a href="' . $node['href'] . '">' . $node['value'] . '</a>';
-            if ($node['children']) {
-                $output .= "\n" . print_tree_rec($node['children'], $level+1);
+            if ($strict_mode) {
+                break;
             }
-            $output .= "</li>\n";
+            array_pop ($lang_code);
         }
-        $output .= "</ul>\n";
-        return $output;
     }
-
-    function print_tree ($params, &$smarty) {
-        if (empty($params['level'])) {
-            $level = 0;
-        } else {
-            $level = $params['level'];
-        }
-        if (empty($params['tree'])) {
-            return '';
-        } else {
-            return print_tree_rec($params['tree'], $level);
+    return $current_lang;
+}
+
+function print_tree_rec($tree, $level) {
+    $output = '<ul class="treelvl' . $level. '">' . "\n";
+    foreach ($tree as $node) {
+        $output .= '<li><a href="' . $node['href'] . '">' . $node['value'] . '</a>';
+        if ($node['children']) {
+            $output .= "\n" . print_tree_rec($node['children'], $level+1);
         }
+        $output .= "</li>\n";
+    }
+    $output .= "</ul>\n";
+    return $output;
+}
+
+function print_tree($params, &$smarty) {
+    if (empty($params['level'])) {
+        $level = 0;
+    } else {
+        $level = $params['level'];
+    }
+    if (empty($params['tree'])) {
+        return '';
+    } else {
+        return print_tree_rec($params['tree'], $level);
     }
+}
 
 ?>
diff --git a/tpl/header.tpl b/tpl/header.tpl
index d88e0dc..0e30e12 100644
--- a/tpl/header.tpl
+++ b/tpl/header.tpl
@@ -6,12 +6,16 @@
 <meta http-equiv="content-type" content="text/html; charset=utf-8">
 <link rel="shortcut icon" href="images/shield.ico">
 <link rel="stylesheet" href="tpl/style.css" type="text/css">
+{if isset($styles)}
 {foreach item=style from=$styles}
 <link rel="stylesheet" href="css/{$style[0]}" type="text/css" media="{$style[1]}" />
 {/foreach}
+{/if}
+{if isset($scripts)}
 {foreach item=script from=$scripts}
 <script type="text/javascript" src="lib/{$script}"></script>
 {/foreach}
+{/if}
 </head>
 
 <body>