GNU bug report logs - #62990
30.0.50; UDP server closes connection upon receiving an empty packet

Previous Next

Full log

View this message in rfc822 format

From: Vasilij Schneidermann <mail <at> vasilij.de>
To: Robert Pluim <rpluim <at> gmail.com>
Cc: 62990 <at> debbugs.gnu.org
Subject: bug#62990: 30.0.50; UDP server closes connection upon receiving an empty packet
Date: Mon, 24 Apr 2023 23:04:34 +0200

[Message part 1 (text/plain, inline)]

> Empty TCP messages are perfectly valid, but they should be hidden from
> you. recvfrom returning 0 means the connection has been closed, but
> thatʼs a separate thing.

I suspect there's a missing ifdef in the code which ends up terminating
the process on such a condition, for both TCP and UDP.

> Could you show how youʼre generating the empty packets?

Download the attachments from my previous email, launch the server with
`emacs --batch -l bug-server.el`, then the client with `guile
fixed-client.scm`. Swap out the server with `guile fixed-server.scm`.

> Itʼs allowed by the protocol. I guess it could be useful for people
> wanting to implement their own keep-alive protocol over UDP.

I think so as well.

[signature.asc (application/pgp-signature, inline)]

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.