Add 300 and update CSS for better code

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askiiart 2023-12-06 11:44:14 -06:00
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<!DOCTYPE html>
<html lang="en">
<head>
<meta content="width=device-width, initial-scale=1" charset="utf-8" />
<link rel="icon" href="/assets/askiiart.gif" type="image/icon">
<title>300</title>
<link href="/style.css" type="text/css" rel="stylesheet" />
<link href="/prism.css" rel="stylesheet" />
</head>
<body class="line-numbers">
<h1 id="section">300</h1>
<p>No, not the movie. I'm a nerd who's spent half their day so
far configuring nginx, it should be obvious at this point.</p>
<hr />
<p>Since I have my code 1) <a
href="https://git.askiiart.net/askiiart/askiiart-net">on my
self-hosted Gitea (soon Forgejo) instance</a>, and 2) <a
href="https://github.com/askiiart/askiiart.github.io">mirrored</a>
on GitHub, I didn't just want to set up a simple <a
href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/308">308
Permanent Redirect</a> from <a href="/.git">/.git</a> to my code
in one place. I wanted users to be able to see both options,
both Gitea and GitHub, and apparently there's actually a thing
for that already, I can just use that!</p>
<h2 id="ok-but-how">ok but how?</h2>
<p>300 seems great, but there's no standardized way to use it.
The number, and the <code>Location</code> header as the
preferred choice is all that's actually standardized. Straight
from <a
href="https://httpwg.org/specs/rfc9110.html#status.300">RFC
9110</a>:</p>
<blockquote>
<p>If the server has a preferred choice, the server
<em>SHOULD</em> generate a Location header field containing a
preferred choice's URI reference. The user agent MAY use the
Location field value for automatic redirection.</p>
<p>For request methods other than HEAD, the server
<em>SHOULD</em> generate content in the 300 response containing
a list of representation metadata and URI reference(s) from
which the user or user agent can choose the one most
preferred.</p>
</blockquote>
<p>Does this mean to return some HTML? A JSON dict? YAML? An
image of a pickle with that info overlaid on top of it!?
<em>Nobody knows!</em> And from the Mozilla docs:</p>
<blockquote>
<p>As there is no standardized way of choosing one of the
responses, this response code is very rarely used.</p>
</blockquote>
<p>Very helpful.</p>
<h2 id="ok-but-actually-how">ok but actually how?</h2>
<p>After a bit of Googling, I found <a
href="https://stackoverflow.com/questions/8905545/what-is-the-exact-response-structure-for-http-status-code-300-multiple-choices">this
Stack Overflow thread</a>, which just says
this<sup>[<a href="#browser-specific-info">note</a>]</sup>:</p>
<blockquote>
<p>The "multiple choices" are done by sending the links in
hypertext (HTML) content and let the <em>user</em> pick.</p>
</blockquote>
<p>Well, that's boring. Guess I'll do that then.</p>
<pre class="language-nginx"><code> location /.git {
add_header Location &quot;https://git.askiiart.net/askiiart/askiiart-net&quot;;
return 300 &#39;&lt;!DOCTYPE html&gt;&lt;html lang=&quot;en&quot;&gt;&lt;head&gt;&lt;meta charset=&quot;utf-8&quot;&gt;&lt;/head&gt;&lt;body&gt;&lt;a href=&quot;https://git.askiiart.net/askiiart/askiiart-net&quot;&gt;Self-hosted&lt;/a&gt;&lt;br&gt;&lt;a href=&quot;https://github.com/askiiart/askiiart-net&quot;&gt;GitHub&lt;/a&gt;&lt;/body&gt;&lt;/html&gt;&#39;;
}</code></pre>
<h2 id="nginx-is-hard">nginx is hard</h2>
<p>That config looks fine, right? It just sets the
<code>Location</code> header and returns this basic menu to pick
from. But it won't open in any browsers, Firefox displays
nothing, and has <code>NS_ERROR_WONT_HANDLE_CONTENT</code> in
the developer tools, and Chrome shows a
<code>ERR_INVALID_RESPONSE</code> error. Running
<code>curl -I https://askiiart.net</code>, and...</p>
<div class="sourceCode" id="cb2"><pre
class="language-sh"><code class="language-bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">HTTP/1.1</span> 300 </span>
<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="ex">Server:</span> nginx/1.25.3</span>
<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="ex">Date:</span> Wed, 06 Dec 2023 16:36:01 GMT</span>
<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="ex">Content-Type:</span> application/octet-stream</span>
<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a><span class="ex">Content-Length:</span> 223</span>
<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a><span class="ex">Connection:</span> keep-alive</span></code></pre></div>
<p>There's no Location header there! And the browsers are
probably refusing to show it because of the wrong
<code>Content-Type</code>—and no, adding a header with
<code>add_header</code> doesn't work for that one, either.</p>
<p>Turns out in order to be able to use <code>add_header</code>,
you first need to set <code>default_type</code> (which sets a
default <code>Content-Type</code>). I could've set that in the
<code>location /.git</code> block, but I just decided to make it
global.</p>
<p>So here's the fixed config:</p>
<pre class="language-nginx"><code> # actually much higher in file
default_type &quot;text/html&quot;;
location /.git {
add_header Location &quot;https://git.askiiart.net/askiiart/askiiart-net&quot;;
return 300 &#39;&lt;!DOCTYPE html&gt;&lt;html lang=&quot;en&quot;&gt;&lt;head&gt;&lt;meta charset=&quot;utf-8&quot;&gt;&lt;/head&gt;&lt;body&gt;&lt;a href=&quot;https://git.askiiart.net/askiiart/askiiart-net&quot;&gt;Self-hosted&lt;/a&gt;&lt;br&gt;&lt;a href=&quot;https://github.com/askiiart/askiiart-net&quot;&gt;GitHub&lt;/a&gt;&lt;/body&gt;&lt;/html&gt;&#39;;
}</code></pre>
<p>Yep, that works! I had set up my IP address pages the same
way, so let's fix that:</p>
<pre class="language-nginx"><code> location /ip {
default_type text/plain;
return 200 &quot;$remote_addr&quot;;
}
location /ip/json {
default_type application/json;
return 200 &#39;{&quot;ip&quot;:&quot;$remote_addr&quot;}&#39;;
}</code></pre>
<p>These still don't work, they just return my reverse proxy
container's gateway's address, but that's for another time.</p>
<h2 id="open-your-eyes...-wake-up-link">Open your eyes... wake
up, <em>Link</em></h2>
<p>Turns out might be a standard way to do it! From <a
href="https://httpwg.org/specs/rfc9110.html#status.300">RFC
9110</a>, again:</p>
<blockquote>
<p>It is possible to communicate the list using a set of Link
header fields <a
href="https://httpwg.org/specs/rfc9110.html#RFC8288">RFC5988</a>,
each with a relationship of "alternate", though deployment is a
chicken-and-egg problem.</p>
</blockquote>
<p>I'll probably figure out the <code>Link</code> header some
other time and will add this later, at which point I'll post an
addendum. Until then, bye I guess!</p>
<h2 id="footnotes-and-stuff">Footnotes and stuff</h2>
<h4 id="browser-specific-info">browser-specific info</h4>
<p>Elsewhere in the Quora thread it says, in short, that Firefox
and Chrome just displays the HTML, and Safari will follow the
<code>Location</code> header. [<a
href="#ok-but-actually-how">Back</a>]</p>
<script src="/prism.js"></script>
</body>
<footer>
<p><a href="https://git.askiiart.net/askiiart/askiiart-net">code</a> (<a href="https://github.com/askiiart/askiiart.github.io">mirror</a>)&emsp;<a href="/feed.xml">rss</a>&emsp;<a href="/pubkey.asc">pubkey</a></p>
</footer>
</html>

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# 300
No, not the movie. I'm a nerd who's spent half their day so far configuring nginx, it should be obvious at this point.
---
Since I have my code 1) [on my self-hosted Gitea (soon Forgejo) instance](https://git.askiiart.net/askiiart/askiiart-net), and 2) [mirrored](https://github.com/askiiart/askiiart.github.io) on GitHub, I didn't just want to set up a simple [308 Permanent Redirect](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/308) from [/.git](/.git) to my code in one place. I wanted users to be able to see both options, both Gitea and GitHub, and apparently there's actually a thing for that already, I can just use that!
## ok but how?
300 seems great, but there's no standardized way to use it. The number, and the `Location` header as the preferred choice is all that's actually standardized. Straight from [RFC 9110](https://httpwg.org/specs/rfc9110.html#status.300):
> If the server has a preferred choice, the server *SHOULD* generate a Location header field containing a preferred choice's URI reference. The user agent MAY use the Location field value for automatic redirection.
>
> For request methods other than HEAD, the server *SHOULD* generate content in the 300 response containing a list of representation metadata and URI reference(s) from which the user or user agent can choose the one most preferred.
Does this mean to return some HTML? A JSON dict? YAML? An image of a pickle with that info overlaid on top of it!? *Nobody knows!* And from the Mozilla docs:
> As there is no standardized way of choosing one of the responses, this response code is very rarely used.
Very helpful.
## ok but actually how?
After a bit of Googling, I found [this Stack Overflow thread](https://stackoverflow.com/questions/8905545/what-is-the-exact-response-structure-for-http-status-code-300-multiple-choices), which just says this<sup>[<a href="#browser-specific-info">note</a>]</sup>:
> The "multiple choices" are done by sending the links in hypertext (HTML) content and let the *user* pick.
Well, that's boring. Guess I'll do that then.
```language-nginx
location /.git {
add_header Location "https://git.askiiart.net/askiiart/askiiart-net";
return 300 '<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"></head><body><a href="https://git.askiiart.net/askiiart/askiiart-net">Self-hosted</a><br><a href="https://github.com/askiiart/askiiart-net">GitHub</a></body></html>';
}
```
## nginx is hard
That config looks fine, right? It just sets the `Location` header and returns this basic menu to pick from. But it won't open in any browsers, Firefox displays nothing, and has `NS_ERROR_WONT_HANDLE_CONTENT` in the developer tools, and Chrome shows a `ERR_INVALID_RESPONSE` error. Running `curl -I https://askiiart.net`, and...
```sh
HTTP/1.1 300
Server: nginx/1.25.3
Date: Wed, 06 Dec 2023 16:36:01 GMT
Content-Type: application/octet-stream
Content-Length: 223
Connection: keep-alive
```
There's no Location header there! And the browsers are probably refusing to show it because of the wrong `Content-Type`—and no, adding a header with `add_header` doesn't work for that one, either.
Turns out in order to be able to use `add_header`, you first need to set `default_type` (which sets a default `Content-Type`). I could've set that in the `location /.git` block, but I just decided to make it global.
So here's the fixed config:
```language-nginx
# actually much higher in file
default_type "text/html";
location /.git {
add_header Location "https://git.askiiart.net/askiiart/askiiart-net";
return 300 '<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"></head><body><a href="https://git.askiiart.net/askiiart/askiiart-net">Self-hosted</a><br><a href="https://github.com/askiiart/askiiart-net">GitHub</a></body></html>';
}
```
Yep, that works! I had set up my IP address pages the same way, so let's fix that:
```language-nginx
location /ip {
default_type text/plain;
return 200 "$remote_addr";
}
location /ip/json {
default_type application/json;
return 200 '{"ip":"$remote_addr"}';
}
```
These still don't work, they just return my reverse proxy container's gateway's address, but that's for another time.
## Open your eyes... wake up, *Link*
Turns out might be a standard way to do it! From [RFC 9110](https://httpwg.org/specs/rfc9110.html#status.300), again:
> It is possible to communicate the list using a set of Link header fields [RFC5988](https://httpwg.org/specs/rfc9110.html#RFC8288), each with a relationship of "alternate", though deployment is a chicken-and-egg problem.
I'll probably figure out the `Link` header some other time and will add this later, at which point I'll post an addendum. Until then, bye I guess!
## Footnotes and stuff
#### browser-specific info
Elsewhere in the Quora thread it says, in short, that Firefox and Chrome just displays the HTML, and Safari will follow the `Location` header. \[[Back](#ok-but-actually-how)\]

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<title>askiiart.net blog</title>
<description>The feed for askiiart.net but just the blog, I guess</description>
<link>https://askiiart.net/blog/</link>
<lastBuildDate>Sun, 19 Nov 2023 23:10:34 +0000</lastBuildDate>
<lastBuildDate>Wed, 06 Dec 2023 17:42:13 +0000</lastBuildDate>
<item>
<title>Marlin Boot Animations</title>
<link>https://askiiart.net/til/marlin-boot-animations.html</link>
</item>
<item>
<title>300</title>
<link>https://askiiart.net/til/300.html</link>
</item>
</channel>
</rss>