+++
title = HTML over DNS: Serving Blog Content Over DNS
date = 2021-08-15
author = Jacob Kiers
+++

## What's up?

You might not be able to see it immediately, but the content of this page is verved over DNS.

This works because of [DNS over HTTPS] for which there is an [API from Cloudflare].

## How it works

That API is used to load the contents of this page, essentially like this:

```js
fetch("https://cloudflare-dns.com/dns-query?ct=application/dns-json&type=TXT&name=post.hod.experiments.jacobkiers.net");
```

The content itself is served over DNS, using CoreDNS, with these contents:

```js
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:

```js
$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.

[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