Toots for reynir@bsd.network account

Written by reynir on 2024-12-20 at 13:45

A few weeks ago we in Robur got on the GitHub Sponsors platform. We wrote a few words about it on our blog: https://blog.robur.coop/articles/2024-12-04-github-sponsor.html

(For various reasons, including me breaking our blogging software by changing the behavior of another package, the article is up on our blog since today)

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Written by reynir on 2024-12-05 at 16:34

So parse_hex() is also used to parse mac addresses. You might see a mac address 1-00:11:22:33:44:55 which says it's hardware type 1 (ethernet (10 Mb)) and mac address 00:11:22:33:44:55.

Interestinly, this means this emoticon my spouse and I sometimes send to each other is also a mac address: :-*

It's the one byte mac address of any value (with an unspecified hardware type, I think). The * for mac addresses is a one byte mask.

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Written by reynir on 2024-12-05 at 16:18

(oh yea I forgot to mention that the totally normal parse_hex() also accepts dashes! They are usually ignored unless parse_hex() has a non-null mac_type output argument)

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Written by reynir on 2024-12-05 at 16:16

Here are some other interesting "equalities":

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Written by reynir on 2024-12-05 at 16:11

Sorry, I think the explanation is wrong, but clearly something fishy is going on. 0x41, 0x42, 0x43, 0x44 is ascii for ABCD which is fine, and then the parser hits :::: and does something really wrong.

A lot of the parser code mutates the input string and parse_hex() is no exception. It's really hard to get a good understanding of what goes on.

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Written by reynir on 2024-12-05 at 16:05

The following two produce a dhcp-host rule with the same dhcp client identifier. In dnsmasq a client identifier with a colon is interpreted as hex:

$ dnsmasq --test --dhcp-host id:ABCD4344

As you can maybe tell the hex parser starts parsing the already decoded data as hex (43 and 44).

(yes, you're allowed to put as many colons in your "hex". And you can put a * in there as well as long as it's not adjacent to a real hexadecimal digit. Dnsmasq's parse_hex() has a really weird concept of hex)

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Written by reynir on 2024-12-05 at 15:51

Great, I think I found an unsafe bug already. In its "hex" parser code.

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Written by reynir on 2024-12-05 at 15:38

Option parsing in dnsmasq is some pretty bonkers code. I might write something about it later.

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Written by reynir on 2024-11-12 at 21:19

I was transferring music files from my computer to my phone. One of the files has a question mark in its name. Apparently this was so unexpected that Nautilus (GNOME file manager) started throwing stack traces all over, and for a while it was impossible for me to mount the phone again.

It took me a while to figure out it was the file name. Renamed the file without the question mark and things went smooth.

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Written by reynir on 2024-10-26 at 09:11

@emily I think this is the change that fixed it: https://github.com/libarchive/libarchive/pull/2127/files#diff-dc0935b631736ce1d3ad08da0faa4b9466d60027ea2ce0a6cd38ac7965a66eb6R1191

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Written by reynir on 2024-10-26 at 09:03

Hi @emily! Your fine article on executable tar archives taught me that the GNU volume header would be perfect for my hybrid GPT+tar header!

Unfortunately, I learnt that it doesn't work with bsdtar - it will complain about a bad archive. However! They "fixed" that in libarchive in April or so! Which hasn't had a release yet, though. I thought you might enjoy this fact.

https://uni.horse/executable-tarballs.html

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Written by reynir on 2024-09-10 at 09:27

rmdir: failed to remove 'empty/': Directory not empty

>:(

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Written by reynir on 2024-08-23 at 10:53

I just learnt that OpenSSH's ForwardAgent option can, besides yes and no, take a path as argument to an ssh-agent. This is really nice! I didn't know. Any idea how old this is? Is it well-supported?

A use case I have in mind is to forward a different (set of) key(s) to a host than the key used to authenticate to the server.

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Written by reynir on 2024-08-19 at 12:59

What is the collective noun for a group of unikernels?

[#]mirage #ocaml #unikernel

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Written by reynir on 2024-08-19 at 09:05

I found this snippet in a commit message in git (6e8e0991e5219954f049731d18e5f53c5f5f526b):

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Written by reynir on 2024-08-14 at 07:14

I read that #inetd hooks up stdin, stdout and stderr of the service program. But what does it hook stderr to? The network socket? Or something else? I struggle a bit with the thought of stderr going over the network...

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