From: Mario Lang <mlang@blind.guru>
To: Robert Pluim <rpluim@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: UDP: Send and receive on same port?
Date: Tue, 30 Mar 2021 23:03:58 +0200 [thread overview]
Message-ID: <878s64e4ld.fsf@blind.guru> (raw)
In-Reply-To: <87pmzg4qd4.fsf@gmail.com> (Robert Pluim's message of "Tue, 30 Mar 2021 17:23:51 +0200")
Robert Pluim <rpluim@gmail.com> writes:
>>>>>> On Tue, 30 Mar 2021 13:11:47 +0200, Mario Lang <mlang@blind.guru> said:
>
> Mario> Replying to self
> Mario> Nevermind, it works by creating a datagram server first, and then using
> Mario> set-process-datagram-address to set the destination. The server process
> Mario> can now be used to send UDP as well. However, I am seeing lost incoming
> Mario> packets. According to tcpdump, the reply is clearly there, but the
> Mario> process filter only seems to pick it up 1 out of roughly 4 times.
> Mario> Weird.
>
> Hmm, I have a patch somewhere to allow setting the sending port
> directly, Iʼll see if I can find it and resurrect it.
OK. However, we'd also need a way to get the listening port of a server
process with :service t. At least I haven't seen a way to query the
listening port yet.
> Having said that, this sounds like it might be a bug (although I
> haven't checked if the emacs code supports sending from a datagram
> server like this).
It does works, and also flawlessly. The weirdness I saw was due to a
coding-system issue, `osc-make-server` did not set :coding 'binary,
which is now fixed.
> Could you open a bug with M-x report-emacs-bug with your emacs
> version, and sample code?
I'd rather not, since this behaviour is actually wanted.
It is the only way I have to communicate with a certain external program
directly from elisp. scsynth always replies to the sender port...
To reproduce, all you need is create a datagram server, and set the
datagram-address to the desired destination. You can now receive
datagrams, and also use process-send-string to send to the desired
destination.
--
CYa,
⡍⠁⠗⠊⠕
next prev parent reply other threads:[~2021-03-30 21:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 8:58 UDP: Send and receive on same port? Mario Lang
2021-03-30 11:11 ` Mario Lang
2021-03-30 15:23 ` Robert Pluim
2021-03-30 21:03 ` Mario Lang [this message]
2021-03-31 9:14 ` Robert Pluim
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