Subj : Re: Packet Radio
To   : Vk3jed
From : tenser
Date : Sun Jan 24 2021 03:14:31

On 22 Jan 2021 at 09:29p, Vk3jed pondered and said...
 
 Vk>  te> Another issue is that the node software has bitrotted to the point
 Vk>  te> of often not working.  I've fixed lots of bugs in mine; it now
 Vk>  te> "works", to a point, but is disappointingly fragile.  It's clear
 Vk>  te> that that code hasn't gotten a lot of love in the modern era.
 Vk> 
 Vk> Which software exactly?

Approximately all of it, but I'm referring specifically to
the AX.25 tools and apps for Linux.  An interesting example
is, "axspawn": this lets hams log into the local (Linux)
host, automatically creating accounts for them if such don't
already exist.  The issue is that it's broken, and loses
data: the Linux AX.25 stack in connected only supports sending
data using the SEQPACKET socket type, which means that
individual write(2) calls must limit the amount of data they
send to fit into a single AX.25 frame.  But the `axspawn`
program doesn't do that; it spawns a pseudo-TTY pair and
runs a shell on the child end, and just writes whatever comes
down the parent side to the socket.  It's easy enough to fix;
one simply chunks those writes up in a loop.  There was also
some hokey rate-limiting stuff built around alarm(3), but it
seemed straight up broken.

I ended up rewriting it to `telnet` to the Dragonfly machine
on my local AMPRNet subnet, so when users connect to my host
they're really `telnet`ing into my host machine, and had to
fix all of that.

Another issue was in the `ttylinkd` daemon: this is basically
an interface to the venerable talkd(8), and speaks the same
weird undocumented protocol.  But its handling of that protocol
was broken (it didn't talk to the local daemon on the right
interface) so I had to fix it.  That was really annoying.

I attribute all of this to this software being overly complex
and essentially unmaintained.  I could fix it locally, but
its tedious.

Who knows what bugs are lurking in the kernel AX.25 implementation?

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