[Toybox] [PATCH] telnetd: handle TIME_WAIT better.

[enh]

On Sat, Apr 24, 2021 at 2:37 AM Rob Landley <rob at landley.net> wrote:

> On 4/22/21 9:00 PM, enh via Toybox wrote:
> > After a network outage, a long-running telnetd was spinning trying to
> > read from a socket that was in TIME_WAIT. It's easy to reproduce this by
> > using the regular telnet client and typing ^]^D to exit abruptly.
>
> Doesn't apply without the previous one. I'll apply the whole stack on the
> theory
> it's in pending so I don't have a strong attachment to what's there, and
> you've
> just put a lot more effort into understanding it than I have so far.
>
> But I don't think telnet should depend on having access to a DNS server
> describing any of the machines involved...
>

this is telnet*d*, not telnet. but, yeah, it's unclear to me whether --
despite the fact that the login argument is called "hostname" -- we're
really supposed to supply the name or just the address[1]. that said, BSD
telnetd even has an option to disallow connections from addresses it can't
do a reverse lookup on (
https://www.freebsd.org/cgi/man.cgi?query=telnetd&sektion=8).

they were different times :-)

____
1. the present code will supply the address rather than the name anyway, in
the case that there's no DNS entry. so unless your objection is "shouldn't
even _try_ DNS", i don't think this makes any practical difference.

Rob
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