From 610c259272cadd57a19905853d75a68eb04d28c1 Mon Sep 17 00:00:00 2001
From: Luke Bratch <luke@bratch.co.uk>
Date: Thu, 13 Apr 2017 00:31:15 +0100
Subject: Offer to automatically increment the zone serial number

---
 dns.php | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/dns.php b/dns.php
index ddae571..b184a95 100644
--- a/dns.php
+++ b/dns.php
@@ -6,6 +6,36 @@ error_reporting(E_ALL);
 define("ZONEROOT", "/var/bind/pri/");
 define("ZONESUFFIX", ".zone");
 
+function incrementserial($zonetext) {
+  $serial = array("");
+  $newserial = "";
+
+  // See if we can detect a serial number
+  if (preg_match("/\(($|^|[[:space:]])*[0-9]{10}([[:space:]]|;|$|^)+/", $zonetext, $matches)) {;
+    // Only bother with the first match
+    preg_match("/[0-9]{10}/", $matches[0], $serial);
+
+    $today = date("Ymd00");
+
+    if ($serial[0] < $today) {
+      $newserial = $today;
+    } else {
+      $newserial = $serial[0] + 1;
+    }
+
+    // The effort below is gone to to avoid replacing more than one match with our *one* new serial number
+
+    // Prepare a string to replace the string we found the serial in
+    $rebuiltstring = str_replace($serial[0], $newserial, $matches[0]);
+    // Escape special regex characters since we need to use preg_replace below to limit to one replacement
+    $escapedmatch = preg_quote($matches[0]);
+
+    $zonetext = preg_replace("/" . $escapedmatch . "/", $rebuiltstring, $zonetext, 1);
+  }
+
+  return array($zonetext, $serial[0], $newserial);
+}
+
 function sshrun($command) {
   $host = "misc.tghost.co.uk";
   $user = "bladns.net";
@@ -48,6 +78,10 @@ function writezone($domain, $password, $zonetext) {
     die("somehow the password went bad");
   }
 
+  if (isset($_POST['increment'])) {
+    $zonetext = incrementserial($zonetext)[0];
+  }
+
   $zonetext = str_replace('$', '\$', $zonetext);
 
   sshrun("echo -e \"$zonetext\" > " . ZONEROOT . "$domain" . ZONESUFFIX);
@@ -67,6 +101,14 @@ if (isset($_POST['domain']) && isset($_POST['password']) && !isset($_POST['zonet
 ?>
     <form action="dns.php" method="post">
     <textarea rows="24" cols="80" name="zonetext" autofocus><?php echo $zonefile; ?></textarea><br>
+<?php
+    $arrincrement = incrementserial($zonefile);
+    if ($arrincrement[0] != $zonefile) {
+?>
+    <input type="checkbox" name="increment" checked>Automatically increment <?php echo $arrincrement[1] . " to " . $arrincrement[2]; ?>?</input><br>
+<?php
+    }
+?>
     <input type="hidden" name="domain" value="<?php echo $_POST['domain']; ?>">
     <input type="hidden" name="password" value="<?php echo $password; ?>">
     <input type="submit" value="Update zonefile"><br>
-- 
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