Update with tech changes.

Signed-off-by: Jacob Kiers <jacob@jacobkiers.net>

Corefile

@@ -0,0 +1,7 @@
+hod.experiments.jacobkiers.net.:53 {
+    log
+    auto hod.experiments.jacobkiers.net. {
+	directory /etc/coredns/zones/
+        reload 10s
+    }
+}

content/posts/2021-08-17-serving-blog-content-over-dns.md

@@ -1,12 +1,18 @@
 +++
-title = Serving blog content over DNS
+title = HTML over DNS: Serving Blog Content Over DNS
 date = 2021-08-15
 author = Jacob Kiers
 +++
 
-You might not be able to see it immediately, but the content of this page is verved over DNS.
+## What's up?
 
-This works because of the new DNS-over-HTTP support, which, at least at Cloudflare, also has an API.
+You might not be able to see it immediately, but the content of this page is served over DNS.
+
+This works because of [DNS over HTTPS] for which there is an [API from Cloudflare].
+
+Comments at [Hacker News, apparently][HN].
+
+## How it works
 
 That API is used to load the contents of this page, essentially like this:
 
@@ -14,6 +20,64 @@ That API is used to load the contents of this page, essentially like this:
 fetch("https://cloudflare-dns.com/dns-query?ct=application/dns-json&type=TXT&name=post.hod.experiments.jacobkiers.net");
 ```
 
-Please see the [source code] for the details of how it works.
+The content itself is served over DNS, using CoreDNS, with these contents:
 
-[source code]: https://github.com/jacobkiers/html-over-dns
+```hcl
+hod.experiments.jacobkiers.net.:53 {
+    log
+    auto hod.experiments.jacobkiers.net. {
+	directory /etc/coredns/zones/
+        reload 10s
+    }
+}
+```
+
+This feeds into a zone file, which looks like this:
+
+```dns
+$TTL 5m	; Default TTL
+@	IN	SOA	experiments.jacobkiers.net.	postmaster.jacobkiers.net. (
+	2021081612	; serial
+	1h		; slave refresh interval
+	15m		; slave retry interval
+	1w		; slave copy expire time
+	1h		; NXDOMAIN cache time
+	)
+
+$ORIGIN hod.experiments.jacobkiers.net.
+
+;
+; domain name servers
+;
+@	IN	NS  experiments.jacobkiers.net.
+
+
+;; START BLOG RECORDS
+; posts-2021-08-17-serving-blog-content-over-dns-md
+posts-2021-08-17-serving-blog-content-over-dns-md	60	IN	TXT	"t=text/markdown;c=3;h=2fd63f0f408ad1336283999d0487ced9;m=eyJ0aXRsZSI6IlNlcnZpbmcgYmxvZyBjb250ZW50IG92ZXIgRE5TIiwiZGF0ZSI6IjIwMjEtMDgtMTUiLCJhdXRob3IiOiJKYWNvYiBLaWVycyJ9"
+0.2fd63f0f408ad1336283999d0487ced9	60	IN	TXT	"WW91IG1pZ2h0IG5vdCBiZSBhYmxlIHRvIHNlZSBpdCBpbW1lZGlhdGVseSwgYnV0IHRoZSBjb250ZW50IG9mIHRoaXMgcGFnZSBpcyB2ZXJ2ZWQgb3ZlciBETlMuCgpUaGlzIHdvcmtzIGJlY2F1c2Ugb2YgdGhlIG5ldyBETlMtb3Zlci1IVFRQIHN1cHBvcnQsIHdoaWNoLCBhdCBsZWFzdCBhdCBDbG91ZGZsYXJlLCBhbHNvIGhhcy"
+1.2fd63f0f408ad1336283999d0487ced9	60	IN	TXT	"BhbiBBUEkuCgpUaGF0IEFQSSBpcyB1c2VkIHRvIGxvYWQgdGhlIGNvbnRlbnRzIG9mIHRoaXMgcGFnZSwgZXNzZW50aWFsbHkgbGlrZSB0aGlzOgoKYGBganMKZmV0Y2goImh0dHBzOi8vY2xvdWRmbGFyZS1kbnMuY29tL2Rucy1xdWVyeT9jdD1hcHBsaWNhdGlvbi9kbnMtanNvbiZ0eXBlPVRYVCZuYW1lPXBvc3QuaG9kLmV4cGVy"
+2.2fd63f0f408ad1336283999d0487ced9	60	IN	TXT	"aW1lbnRzLmphY29ia2llcnMubmV0Iik7CmBgYAoKUGxlYXNlIHNlZSB0aGUgW3NvdXJjZSBjb2RlXSBmb3IgdGhlIGRldGFpbHMgb2YgaG93IGl0IHdvcmtzLgoKW3NvdXJjZSBjb2RlXTogaHR0cHM6Ly9naXRodWIuY29tL2phY29ia2llcnMvaHRtbC1vdmVyLWRucwo="
+```
+
+These records are base64 encoded content, so when concatenated and decoded, they give the content of the posts.
+
+Please see the [source code] for the details.
+
+## FAQ
+
+### Why, though?
+
+In short: just because I could. It was one of those ideas I was wondering idly about, and I decided to just try it.
+
+### Has it any practical use?
+
+It is not intended to have any. Since DNS records are fairly small, serving images or something would quickly start
+consuming 100s of requests per second. I wouldn't want to do that to Cloudflare.
+
+It would be an interesting experiment to see how feasible that is.
+
+[source code]: https://github.com/jacobkiers/html-over-dns "Yes, the title is a pun..."
+[DNS over HTTPS]: https://en.wikipedia.org/wiki/DNS_over_HTTPS
+[API from Cloudflare]: https://developers.cloudflare.com/1.1.1.1/dns-over-https/json-format
+[HN]: https://news.ycombinator.com/item?id=28218406

content/scripts/verifier.js

@@ -0,0 +1,21 @@
+class Verifier {
+    /***
+     * @param content Content
+     */
+    async verify(content) {
+        if (!window.isSecureContext) return;
+        if (typeof TextEncoder === "undefined") return;
+        if (typeof crypto === "undefined") return;
+        const encoder = new TextEncoder();
+        const digestBuffer = await crypto.subtle.digest(content.index.hashAlgorithm, encoder.encode(content.content));
+
+        const hashArray = Array.from(new Uint8Array(digestBuffer));                     // convert buffer to byte array
+        const digest = hashArray.map(b => b.toString(16).padStart(2, '0')).join(''); // convert bytes to hex string
+
+        if (content.index.hash === digest) {
+            document.getElementById("verification").innerHTML =
+                "The hash of the content is verified to correspond with the hash" +
+                " in the metadata. You are now reading exactly what was intended.";
+        }
+    }
+}

index.html

@@ -1,140 +0,0 @@
-<!DOCTYPE html charset="UTF-8">
-<html>
-
-<head>
-<meta charset="UTF-8">
-<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@11.2.0/build/styles/default.min.css">
-<script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@11.2.0/build/highlight.min.js"></script>
-<script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
-<script>
-class Content {
-    content = "";
-    type = "";
-    metaData = {}
-
-    constructor(content, type, metaData = {})
-    {
-        this.content = content;
-        this.type = type;
-        this.metaData = metaData;
-    }
-}
-
-class Index 
-{
-    mimeType = "";
-    chunks = 0;
-    hash = "";
-    metaData = {};
-
-    constructor(mimeType, chunks, hash, metaData = {})
-    {
-        this.mimeType = mimeType;
-        this.chunks = chunks;
-        this.hash = hash;
-        this.metaData = metaData
-    }
-}
-
-const dohServer = "https://cloudflare-dns.com/dns-query?ct=application/dns-json&type=TXT&name=";
-const baseDomain = "hod.experiments.jacobkiers.net";
-
-async function readUrl(domain) {
-    var index = await fetchIndex(`${dohServer}${domain}.${baseDomain}`);
-
-    var chunk_promises = [];
-    for(i = 0; i < index.chunks; i++)
-    {
-        chunk_promises[i] = fetchChunk(i, index.hash);
-    }
-
-    var chunks = await Promise.all(chunk_promises);
-    var content = chunks.reduce((built, current) => built += current);
-
-    return handleContent(new Content(atob(content), index.mimeType, index.metaData));
-}
-
-async function fetchChunk(id, hash)
-{
-    var domain = `${id}.${hash}.${baseDomain}`;
-    const json = await fetch(`${dohServer}${domain}`)
-        .then(response => response.json());
-
-    const data = json.Answer[0].data.slice(1, -1);
-
-    return data;
-}
-
-async function fetchIndex(domain)
-{
-    const response = await fetch(`${dohServer}.${domain}`);
-    const json = await response.json();
-    const index = json.Answer[0].data.slice(1, -1);
-    
-    let ret = {};
-    let items = index.split(';');
-    items.forEach(item => {
-        let md = item.split('=');
-        let key = md[0];
-        let value = md[1];
-
-        ret[key] = value;
-    });
-
-    const metadata = JSON.parse(atob(ret["m"]));
-    return new Index(ret["t"], ret["c"], ret["h"], metadata);
-}
-
-function handleContent(content)
-{
-    if (!content instanceof Content) {
-        console.log("Not valid content in handleContent.")
-        return;
-    }
-
-    switch(content.type)
-    {
-        case "text/javascript":
-            return handleJavascript(content);
-        
-        case "text/markdown":
-            return handleMarkdown(content);
-
-        default:
-            console.log(`handleContent() does not know how to parse ${content.type}`);
-            break;
-    }
-}
-
-function handleJavascript(content)
-{
-    console.log("Got some javascript!", content.content);
-}
-
-async function handleMarkdown(content)
-{
-    console.log("Got me some markdown!");
-    marked.setOptions({
-        highlight: function(code, lang) {
-            return hljs.highlight(lang, code).value;
-        },
-        // langPrefix: ''
-    });
-
-    if (content.metaData.title != undefined) document.title = content.metaData.title;
-    document.getElementById("post").innerHTML = marked(content.content);
-    let title = document.createElement("h1");
-    title.innerHTML = content.metaData.title;
-    document.getElementById("post").prepend(title)
-}
-</script>
-</head>
-<body>
-  <script>
-readUrl("posts-2021-08-17-serving-blog-content-over-dns-md");
-
-  </script>
-  <div id="post"></div>
-</body>
-
-</html>

public/equilibrium-light.min.css

@@ -0,0 +1,7 @@
+/*!
+  Theme: Equilibrium Light
+  Author: Carlo Abelli
+  License: ~ MIT (or more permissive) [via base16-schemes-source]
+  Maintainer: @highlightjs/core-team
+  Version: 2021.05.0
+*/pre code.hljs{display:block;overflow-x:auto;padding:1em}code.hljs{padding:3px 5px}.hljs{color:#43474e;background:#f5f0e7}.hljs ::selection{color:#d8d4cb}.hljs-comment{color:#73777f}.hljs-tag{color:#5a5f66}.hljs-operator,.hljs-punctuation,.hljs-subst{color:#43474e}.hljs-operator{opacity:.7}.hljs-bullet,.hljs-deletion,.hljs-name,.hljs-selector-tag,.hljs-template-variable,.hljs-variable{color:#d02023}.hljs-attr,.hljs-link,.hljs-literal,.hljs-number,.hljs-symbol,.hljs-variable.constant_{color:#bf3e05}.hljs-class .hljs-title,.hljs-title,.hljs-title.class_{color:#9d6f00}.hljs-strong{font-weight:700;color:#9d6f00}.hljs-addition,.hljs-code,.hljs-string,.hljs-title.class_.inherited__{color:#637200}.hljs-built_in,.hljs-doctag,.hljs-keyword.hljs-atrule,.hljs-quote,.hljs-regexp{color:#007a72}.hljs-attribute,.hljs-function .hljs-title,.hljs-section,.hljs-title.function_,.ruby .hljs-property{color:#0073b5}.diff .hljs-meta,.hljs-keyword,.hljs-template-tag,.hljs-type{color:#4e66b6}.hljs-emphasis{color:#4e66b6;font-style:italic}.hljs-meta,.hljs-meta .hljs-keyword,.hljs-meta .hljs-string{color:#c42775}.hljs-meta .hljs-keyword,.hljs-meta-keyword{font-weight:700}

public/index.html

@@ -0,0 +1,178 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="UTF-8">
+<title>Blog over DNS</title>
+<link rel="stylesheet" href="equilibrium-light.min.css">
+<script src="highlight.min.js"></script>
+<script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
+<script>
+class Content {
+    content = "";
+    type = "";
+    metaData = {};
+    index;
+
+    /***
+     * @param content string
+     * @param type string
+     * @param index Index
+     */
+    constructor(content, type, index)
+    {
+        this.content = content;
+        this.type = type;
+        this.index = index;
+        this.metaData = index.metaData;
+    }
+}
+
+class Index
+{
+    mimeType = "";
+    chunks = 0;
+    hashAlgorithm = "";
+    hash = "";
+    metaData = {};
+
+    constructor(mimeType, chunks, hash, hashAlgorithm, metaData = {})
+    {
+        this.mimeType = mimeType;
+        this.chunks = chunks;
+        this.hashAlgorithm = hashAlgorithm;
+        this.hash = hash;
+        this.metaData = metaData
+    }
+}
+
+const dohServer = "https://cloudflare-dns.com/dns-query?ct=application/dns-json&type=TXT&name=";
+const baseDomain = "hod.experiments.jacobkiers.net";
+
+async function readUrl(domain) {
+    var index = await fetchIndex(`${domain}.${baseDomain}`);
+
+    var chunk_promises = [];
+    for(i = 0; i < index.chunks; i++)
+    {
+        chunk_promises[i] = fetchChunk(i, index.hash);
+    }
+
+    const chunks = await Promise.all(chunk_promises);
+    const base64 = chunks.reduce((built, current) => built += current);
+
+    const content = atob(base64);
+    return handleContent(new Content(content, index.mimeType, index));
+}
+
+async function fetchChunk(id, hash)
+{
+    const domain = `${id}.${hash}.${baseDomain}`;
+    return await fetchData(domain);
+}
+
+async function fetchData(domain)
+{
+    const json =  await fetch(`${dohServer}${domain}`, {
+            method: "GET",
+            headers: {
+                "Accept": "application/dns-json"
+            }
+        })
+        .then(response => response.json());
+    const raw_data = json.Answer[0].data;
+    const data = raw_data.replaceAll(/[\s\"]/g, '');
+    return data;
+}
+
+async function fetchIndex(domain)
+{
+    const index = await fetchData(domain);
+
+    let ret = {};
+    let items = index.split(';');
+    items.forEach(item => {
+        let md = item.split('=');
+        let key = md[0];
+        let value = md[1];
+
+        ret[key] = value;
+    });
+
+    const metadata = JSON.parse(atob(ret["m"]));
+    return new Index(ret["t"], ret["c"], ret["h"], ret["ha"], metadata);
+}
+
+function handleContent(content)
+{
+    if (!content instanceof Content) {
+        console.log("Not valid content in handleContent.")
+        return;
+    }
+
+    switch(content.type)
+    {
+        case "text/javascript":
+            return handleJavascript(content);
+
+        case "text/markdown":
+            return handleMarkdown(content);
+
+        default:
+            console.log(`handleContent() does not know how to parse ${content.type}`);
+            break;
+    }
+}
+
+function handleJavascript(content)
+{
+    console.log("Got some javascript!");
+    const scripts = document.getElementById("scripts");
+    const new_script = document.createElement("script");
+    new_script.text = content.content;
+
+    scripts.appendChild(new_script);
+}
+
+async function handleMarkdown(content)
+{
+    console.log("Got me some markdown!");
+    marked.setOptions({
+        highlight: function(code, lang) {
+            const avialable_languages = hljs.listLanguages();
+            const has_language = hljs.getLanguage(lang);
+            if (typeof has_language === "undefined") return code;
+            const result = hljs.highlight(code, { language: lang, ignoreIllegals: true});
+            return result.value;
+        },
+    });
+
+    if (typeof content.metaData.title !== "undefined") document.title = content.metaData.title;
+    document.getElementById("post").innerHTML = marked.parse(content.content);
+    let title = document.createElement("h1");
+    title.innerHTML = content.metaData.title;
+    document.getElementById("post").prepend(title)
+    document.getElementById("nojs").remove();
+
+    if (typeof Verifier !== "undefined") {
+        await (new Verifier()).verify(content);
+    }
+}
+</script>
+</head>
+<body>
+    <div id="post"></div>
+  <div id="verification"></div>
+  <div id="nojs">
+      <h1>HTML over DNS</h1>
+      <p>The content of this page is fetched using DNS over HTTP. Since that requires Javascript, please enable that to see the content.</p>
+  </div>
+    <div id="scripts">
+        <script>
+            readUrl("scripts-verifier-js").then(
+                () => readUrl("posts-2021-08-17-serving-blog-content-over-dns-md")
+            );
+        </script>
+    </div>
+</body>
+
+</html>

publish-zones.php

@@ -1,116 +1,325 @@
 <?php declare(strict_types=1);
+if (!defined('EOL')) {
+    define('EOL', "\n");
+}
 
-class Content
+class ContentFile
 {
-    public string $data;
-    public string $mimeType;
-    public string $fileName;
-    public string $hash;
+    private string $filePath;
+    private string $data;
+    private string $fileName;
     private array $metadata = [];
 
-    const TTL = 60;
+    #const RECORD_TTL = 60 * 60 * 24 * 30; // 30 days.
+    const RECORD_TTL = 60; // Keep it short for now, so it is easier to experiment.
+    const METADATA_TTL = 60; // Keep it short for now, so it is easier to update the content.
+    const RECORD_LENGTH = 1536;
 
     public function __construct(string $file)
     {
+        $this->filePath = $file;
         $this->fileName = basename(dirname($file)).'/'.basename($file);
         $this->data = file_get_contents($file);
-        $this->hash = md5($this->data);
 
         $this->parseMetadata();
     }
 
-    public function toRecords(): string
+    /**
+     * @return Record[]
+     */
+    private function toRecords(): array
     {
-        $chunks = str_split(base64_encode($this->data), 250);
+        $chunks = $this->calculateChunks();
+        $hash = $this->calculateHash();
 
-        $records = [];
-        $records[] = "; {$this->getDnsName()}";
-        $records[] = $this->getDnsName().$this->buildMiddle().'"'.$this->buildIndexString(count($chunks)).'"';
-
-        foreach($chunks as $id => $chunk)
-        {
+        $records = [$this->buildMetadataRecord(count($chunks), $hash)];
+        foreach ($chunks as $id => $chunk) {
             $records[] = $this->buildRecord($id, $chunk);
         }
 
+        return $records;
+    }
+
+    public function __toString(): string
+    {
         $result = "";
-        foreach ($records as $record)
-        {
-            $result .= $record . PHP_EOL;
+
+        foreach ($this->toRecords() as $record) {
+            $result .= $record.EOL;
         }
 
         return $result;
     }
 
-    private function getDnsName(): string
+    public function getDnsName(): string
     {
         return str_replace(['/', '\\', '.'], '-', $this->fileName);
     }
 
-    private function buildIndexString(int $chunkCount): string
+    private function buildMetadataRecord(int $chunkCount, string $hash): Record
+    {
+        return (new Record())
+            ->setDnsName($this->getDnsName())
+            ->setTtl(self::METADATA_TTL)
+            ->setContent($this->buildIndexString($chunkCount, $hash));
+    }
+
+    private function buildIndexString(int $chunkCount, $hash): string
     {
         $metadata = base64_encode(json_encode($this->metadata));
-        return "t={$this->mimeType()};c={$chunkCount};h={$this->hash};m={$metadata}";
+
+        return '"'."t={$this->mimeType()};c={$chunkCount};ha=sha-1;h={$hash};m={$metadata}".'"';
     }
 
-    private function buildMiddle(): string
+    private function buildRecord(int $id, string $data): Record
     {
-        return "\t".self::TTL."\tIN\tTXT\t";
+        $name = "$id.{$this->calculateHash()}";
+
+        return (new Record())
+            ->setContent($data)
+            ->setDnsName($name)
+            ->setTtl(self::RECORD_TTL);
     }
 
-    private function buildRecord(int $id, string $data): string
-    {
-        $name = "$id.{$this->hash}";
-
-        return "$name".$this->buildMiddle().'"'.$data.'"';
-    }
-
-    private function mimeType()
+    private function mimeType(): string
     {
         $extension = pathinfo($this->fileName, PATHINFO_EXTENSION);
 
-        switch($extension)
-        {
+        switch ($extension) {
             case "js":
                 return "text/javascript";
             case "md":
                 return "text/markdown";
-            
+
             default:
-                return mime_content_type($this->file);
+                return mime_content_type($this->filePath);
         }
     }
 
-    private function parseMetadata()
+    private function parseMetadata(): void
     {
-        if ($this->mimeType() != "text/markdown") return [];
-
-        $frontmatter_chars = "+++";
-
-        $end_of_frontmatter = strpos($this->data, $frontmatter_chars, 2);
-        if (false === $end_of_frontmatter) {
-            var_dump($end_of_frontmatter);
-            return [];
+        if ($this->mimeType() != "text/markdown") {
+            return;
         }
 
-        $frontmatter = substr(
+        $front_matter_chars = "+++";
+
+        $front_matter_end = strpos($this->data, $front_matter_chars, 2);
+        if (false === $front_matter_end) {
+            return;
+        }
+
+        $front_matter = substr(
             $this->data,
-            strlen($frontmatter_chars) + 1,
-            $end_of_frontmatter - strlen($frontmatter_chars) - 2
+            strlen($front_matter_chars) + 1,
+            $front_matter_end - strlen($front_matter_chars) - 2
         );
 
-        $this->data = trim(substr($this->data, $end_of_frontmatter + strlen($frontmatter_chars))).PHP_EOL;
+        $this->data = trim(substr($this->data, $front_matter_end + strlen($front_matter_chars))).EOL;
 
-        $lines = explode(PHP_EOL, $frontmatter);
-        foreach($lines as $line) {
+        $lines = explode(EOL, $front_matter);
+        foreach ($lines as $line) {
             $eq_pos = strpos($line, "=");
             $key = trim(substr($line, 0, $eq_pos - 1));
             $value = trim(substr($line, $eq_pos + 1));
             $this->metadata[$key] = $value;
         }
     }
+
+    private function calculateHash(): string
+    {
+        return sha1($this->data);
+    }
+
+    private function calculateChunks(): array
+    {
+        return str_split(base64_encode($this->data), self::RECORD_LENGTH);
+    }
 }
 
-function update_serial_line(string $line)
+class Record
+{
+    private string $dnsName;
+    private int $ttl;
+    private string $content;
+
+    public function setDnsName(string $dnsName): self
+    {
+        $this->dnsName = $dnsName;
+
+        return $this;
+    }
+
+    public function setTtl(int $ttl): self
+    {
+        $this->ttl = $ttl;
+
+        return $this;
+    }
+
+    public function setContent(string $content): self
+    {
+        $this->content = $content;
+
+        return $this;
+    }
+
+    public function getRecord(): string
+    {
+        return $this->dnsName
+            ."\t".$this->ttl
+            ."\tIN"
+            ."\tTXT\t"
+            .$this->content;
+    }
+
+    public function __toString(): string
+    {
+        return $this->getRecord();
+    }
+}
+
+class StartOfAuthority
+{
+    public function __construct(
+        private string $origin,
+        private string $serial,
+        private string $masterDnsServer,
+        private string $domainContact,
+        private int $slaveRefreshInterval,
+        private int $slaveRetryInterval,
+        private int $slaveCopyExpireTime,
+        private int $nxDomainCacheTime
+    ) {
+    }
+
+    public function doNotUserMasterDnsServer(): self
+    {
+        $servers = $this->dnsServers;
+        $this->dnsServers = array_filter(
+            $servers,
+            function ($server) {
+                return $server !== $this->masterDnsServer;
+            }
+        );
+
+        return $this;
+    }
+
+    public function increaseSerial(): self
+    {
+        $matches = [];
+        preg_match('#(\d{8})(\d{2})#', $this->serial, $matches);
+        list (, $day, $count) = $matches;
+
+        $today = date("Ymd");
+        if ($today === $day) {
+            $count++;
+        } else {
+            $count = 0;
+        }
+
+        $this->serial = sprintf('%1$s%2$02d', $today, $count);;
+
+        return $this;
+    }
+
+    public function __toString(): string
+    {
+        return <<<EOF
+\$ORIGIN $this->origin  ; The zone of this zone file
+@   IN  SOA $this->masterDnsServer  $this->domainContact (
+    $this->serial   ; serial
+    $this->slaveRefreshInterval ; slave refresh interval
+    $this->slaveRetryInterval   ; slave retry interval
+    $this->slaveCopyExpireTime  ; slave copy expire time
+    $this->nxDomainCacheTime    ; NXDOMAIN cache time
+)
+
+;
+; domain name servers
+;
+@   IN  NS  $this->masterDnsServer
+EOF;
+    }
+
+    public static function fromString(string $zonefile): self
+    {
+        $matches = [];
+        $found = 1 === preg_match(
+                '#\$ORIGIN\s+(?P<origin>[a-z.]+)[^@]+@\s+IN\s+SOA\s+(?P<dns>[a-z.]+)\s+(?P<contact>[a-z.]+)\s+\(\D+\s+(?P<serial>\d+)\D+(?P<srefresh>\d+)\D+(?P<sretry>\d+)\D+(?P<sexpire>\d+)\D+(?P<nxcache>\d+)[^\)]+\)#im',
+                $zonefile,
+                $matches
+            );
+
+        if (!$found) {
+            throw new \Exception("Could not find the SOA record.");
+        }
+
+        return new self(
+            $matches['origin'],
+            $matches['serial'],
+            $matches['dns'],
+            $matches['contact'],
+            (int)$matches['srefresh'],
+            (int)$matches['sretry'],
+            (int)$matches['sexpire'],
+            (int)$matches['nxcache']
+        );
+    }
+
+}
+
+class ZoneFile
+{
+    private StartOfAuthority $soa;
+    /** @var ContentFile[] */
+    private array $files = [];
+    private int $defaultTTL = 300;
+
+    public function __construct(
+        private string $file
+    ) {
+        $this->soa = StartOfAuthority::fromString(file_get_contents($this->file));
+    }
+
+    public function addFile(ContentFile ...$files): self
+    {
+        foreach ($files as $file) {
+            $this->files[] = $file;
+        }
+
+        return $this;
+    }
+
+    public function setDefaultTTL(int $defaultTTL): self
+    {
+        $this->defaultTTL = $defaultTTL;
+
+        return $this;
+    }
+
+    public function __toString(): string
+    {
+        $this->soa->increaseSerial();
+
+        $zone_file = "\$TTL\t{$this->defaultTTL}\t; Default TTL".EOL.EOL;
+        $zone_file .= $this->soa->__toString().EOL.EOL.EOL;
+        $zone_file .= ";;; START BLOG RECORDS";
+
+        foreach ($this->files as $file) {
+            $zone_file .= EOL.EOL.EOL;
+            $zone_file .= '; '.$file->getDnsName().EOL;
+            $zone_file .= $file;
+        }
+
+        $zone_file .= EOL;
+
+        return $zone_file;
+    }
+}
+
+function update_serial_line(string $line): string
 {
     $matches = [];
     preg_match("#(\s+)(\d{10})(.*)#", $line, $matches);
@@ -118,7 +327,7 @@ function update_serial_line(string $line)
 
     $today = date("Ymd");
     $day = substr($serial, 0, 8);
-    $nr = (int) substr($serial, -2);
+    $nr = (int)substr($serial, -2);
 
     if ($day === $today) {
         $nr++;
@@ -132,41 +341,68 @@ function update_serial_line(string $line)
     return $start.$new_serial.$last;
 }
 
-$zone_file = "zones/db.hod.experiments.jacobkiers.net";
-if (!file_exists($zone_file)) {
-    fwrite(STDERR, "The zone file {$zone_file} does not exist!");
+$zone_file_path = "zones/db.hod.experiments.jacobkiers.net";
+if (!file_exists($zone_file_path)) {
+    fwrite(STDERR, "The zone file {$zone_file_path} does not exist!");
     exit(1);
 }
-
+/*
 $lines = file($zone_file);
 
-foreach($lines as $index => &$line)
-{
+$index = 0;
+foreach ($lines as $index => &$line) {
     if (str_contains($line, "; serial")) {
         $matches = [];
         preg_match("#(\s+)(\d{10})(.*)#", $line, $matches);
         list($_, $start, $serial, $last) = $matches;
-        $line = update_serial_line($line).PHP_EOL;
+        $line = update_serial_line($line).EOL;
+    }
+    if (str_starts_with($line, ";; START BLOG RECORDS")) {
+        break;
     }
-    if (str_starts_with($line, ";; START BLOG RECORDS")) break;
 }
 
-$zone_file_contents = implode("", array_slice($lines, 0, $index+1));
+
+
+$zone_file_contents = implode("", array_slice($lines, 0, $index + 1));
 
 echo $zone_file_contents;
 
 $it = new RecursiveIteratorIterator(new RecursiveDirectoryIterator(__DIR__."/content"));
-foreach ($it as $file)
-{
-    if ($file->isDir()) continue;
-    if (str_contains($file->getPathname(), "ignore")) continue;
+foreach ($it as $file) {
+    if ($file->isDir()) {
+        continue;
+    }
+    if (str_contains($file->getPathname(), "ignore")) {
+        continue;
+    }
 
-    $bootstrap = new Content($file->getPathname());
-    $zone_file_contents .= PHP_EOL.$bootstrap->toRecords().PHP_EOL;
+    $content = new ContentFile($file->getPathname());
+    $zone_file_contents .= EOL.$content->__toString().EOL;
 }
 
-$zone_file_contents .= PHP_EOL;
+$zone_file_contents .= EOL;
 
-#echo $zone_file_contents;
+echo $zone_file_contents;
 
-file_put_contents($zone_file, $zone_file_contents);
+#file_put_contents($zone_file, $zone_file_contents);
+*/
+
+$zone_file = new ZoneFile($zone_file_path);
+
+$it = new RecursiveIteratorIterator(new RecursiveDirectoryIterator(__DIR__."/content"));
+foreach ($it as $file) {
+    if ($file->isDir()) {
+        continue;
+    }
+    if (str_contains($file->getPathname(), "ignore")) {
+        continue;
+    }
+
+    $content = new ContentFile($file->getPathname());
+    $zone_file->addFile($content);
+}
+
+$zone_file_contents = $zone_file->__toString();
+echo $zone_file_contents;
+file_put_contents($zone_file_path, $zone_file_contents);

zones/db.hod.experiments.jacobkiers.net

@@ -1,19 +1,18 @@
-;
-$TTL 5m	; Default TTL
-@	IN	SOA	home.kie.rs.	postmaster.kie.rs. (
-	2021081611	; serial
-	1h		; slave refresh interval
-	15m		; slave retry interval
-	1w		; slave copy expire time
-	1h		; NXDOMAIN cache time
-	)
+$TTL	300	; Default TTL
 
-$ORIGIN hod.experiments.jacobkiers.net.
+$ORIGIN hod.experiments.jacobkiers.net.  ; The zone of this zone file
+@   IN  SOA experiments.jacobkiers.net.  postmaster.jacobkiers.net. (
+    2021082109   ; serial
+    3600 ; slave refresh interval
+    900   ; slave retry interval
+    604800  ; slave copy expire time
+    3600    ; NXDOMAIN cache time
+)
 
 ;
 ; domain name servers
 ;
-@	IN	NS	    home.kie.rs.
+@	IN	NS	    experiments.jacobkiers.net.
 
 
 ;; START BLOG RECORDS