From 16c2130e0b562f2452e5f2aa4e48e9e7345c22e8 Mon Sep 17 00:00:00 2001
From: Luke Bratch <luke@bratch.co.uk>
Date: Sun, 28 Dec 2025 01:46:05 +0000
Subject: Add support for updating TXT records.

---
 dns.php | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 65 insertions(+), 3 deletions(-)

diff --git a/dns.php b/dns.php
index 95ace68..7ca8174 100644
--- a/dns.php
+++ b/dns.php
@@ -212,6 +212,63 @@ if (isset($_GET['mode']) && isset($_GET['zone']) && isset($_GET['hash'])) {
       writezone($_GET['zone'], $newzonetext);
       echo "<p>record&#40;s&#41; updated :)</p>";
     }
+
+  } else if ($_GET['mode'] == "txt" && isset($_POST['record'])) {
+    $zonetext = getzone($_GET['zone']);
+    // Only use \n for newlines
+    $zonetext = str_replace("\r", "", $zonetext);
+    // Split into individual lines
+    $zonelines = explode("\n", $zonetext);
+    $matches = array();
+    // Find lines that ended with the hash provided (if any)
+    $i = 0;
+    foreach ($zonelines as $line) {
+      if (preg_match("/^[^;].*;.*" . $_GET['hash'] . "$/", $line)) {
+        array_push($matches, array($i, $line));
+      }
+      $i++;
+    }
+
+    // Go through the lines that matched the hash and see if we can find an update to do
+    foreach ($matches as $arrline) {
+      $line = $arrline[1];
+      // Get rid of the comment
+      $exploded = explode(";", $line);
+      $record = $exploded[0];
+      // Split into individual components
+      $parts = preg_split("/\s+/", $record);
+      // Make sure the last element isn't blank (would happen if the comment had a space before it)
+      while ($parts[sizeof($parts) - 1] == "") {
+        array_pop($parts);
+      }
+
+      $parts[sizeof($parts) - 1] = $_POST['record'];
+
+      // Update original zone file array with the new line at the correct position
+      $zonelines[$arrline[0]] = preg_replace('/((TXT|txt)\s+)[^;]+(;.*)/', "$1" . $parts[sizeof($parts) - 1] . " $3", $line);
+    }
+
+    // Next we need to turn the zone file array back into a string again
+    $newzonetext = "";
+    // If the last element was blank, remove it since we'll add a new blank ourselves
+    if ($zonelines[sizeof($zonelines) - 1] == "") {
+      array_pop($zonelines);
+    }
+    // Do the actual converstion to string
+    foreach ($zonelines as $line) {
+      $newzonetext .= $line . "\n";
+    }
+    // See if there was actually a change as a result of this request...
+    if ($zonetext == $newzonetext) {
+      // ...if not, abandon ship
+      echo "<p>no changes detected :)</p>";
+    } else {
+      // ...if so, increment the serial number and...
+      $newzonetext = incrementserial($newzonetext)[0];
+      // ...finally write the zone with the updated record(s)
+      writezone($_GET['zone'], $newzonetext);
+      echo "<p>record&#40;s&#41; updated :)</p>";
+    }
   }
 } else if (isset($_POST['domain']) && isset($_POST['password']) && !isset($_POST['zonetext'])) {
   if (!preg_match('/^[0-9A-Za-z\.\-]*$/', $_POST['domain'])) {
@@ -224,14 +281,19 @@ if (isset($_GET['mode']) && isset($_GET['zone']) && isset($_GET['hash'])) {
 ?>
     <p>1. Your zonefile is below.</p>
     <p>2. Ensure the first line always ends with a SHA-256 hash of your chosen password.</p>
-    <p>3. To automatically update a particular record, give the line a comment ending with a secret ID &#40;e.g. a SHA-256 hash&#41;, e.g.:</p>
+    <p>3. To automatically update a particular A or AAAA record with the source IP address of your request, give the line a comment ending with a secret ID &#40;e.g. a SHA-256 hash&#41;, e.g.:</p>
     <pre>
 test    300     IN      A       192.168.0.1 ; sha256 = 7f480e744a79953eb916b68f540e0eeec6f9cf23edf4aa08cc1cdf5f077c0f6f
 test    300     IN      AAAA    ::1 ; sha256 = b493d48364afe44d11c0165cf470a4164d1e2609911ef998be868d46ade3de4e
     </pre>
-    <p>And then do an HTTP&#40;S&#41; request to:</p>
+    <p>Then do an HTTP&#40;S&#41; GET request to:</p>
     <pre>https://bladns.net/dns.php?mode=update&zone=<strong>yourdomain.tld</strong>&hash=<strong>yourid</strong></pre>
-    <p>Your record will be updated with the IP you did the request from.</p>
+    <p>Your record will be updated with the IP address you did the request from.</p>
+    <p>4. To update a TXT record, do an HTTP(S) POST request to:</p>
+    <pre>https://bladns.net/dns.php?mode=txt&zone=<strong>yourdomain.tld</strong>&hash=<strong>yourid</strong></pre>
+    <p>Include a POST value named "record" containing the text you would like in the TXT record.  Example cURL:</p>
+    <pre>curl "https://bladns.net/dns.php?mode=txt&zone=<strong>yourdomain.tld</strong>&hash=<strong>yourid</strong>" --data-raw 'record="foo bar baz"'</pre>
+    <p></p>
     <form action="dns.php" method="post">
     <textarea rows="24" cols="80" name="zonetext" autofocus><?php echo $zonefile; ?></textarea><br>
 <?php
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