[PD] UDP server with Pd

Roman Haefeli reduzent at gmail.com
Wed Jun 2 15:55:57 CEST 2021

(replying to list as - I believe - you intended to)

On Wed, 2021-06-02 at 09:34 -0400, Martin Peach wrote:
> On Wed, Jun 2, 2021 at 3:31 AM Roman Haefeli <reduzent at gmail.com>
> wrote:
> > On Tue, 2021-06-01 at 19:19 -0400, Martin Peach wrote:
> > > A [udpsend] normally has a different port number to the one it
> > > sends
> > > to, but a [udpreceive] in the same Pd process can still receive
> > > on
> > > that port.
> > 
> > My understanding is that a client won't accept messages with a
> > different source port than it has sent to. Also, such packets
> > wouldn't
> > be able to traverse NAT firewalls.
> > 
> A udp packet almost always has a different source port from its
> destination. It's not the same as TCP as there is no real
> "connection"
> established or maintained, it's just fire and forget. I modified the
> udp objects in response to a request to do just that: send back to
> the
> same port.

You're absolutely right. I think my wording was not clear. Sorry for

When a client with bind port 52333 sends a packet to the server
listening on port 5000, it won't accept response packets from the
server with (matching) destination port 52333 and (different) source
port 5001. [udpsend] on the server side cannot use bind_port=5000,
because it is already used by [udpreceive]. And from what I see in the
documentation, [udpsend] doesn't support setting a bind port, it seems
to pick a random one (which is the normal thing to do when acting as a
client, but not sufficient for a server response to a client request).

So, I believe my goal can (so far) only be achieved with [netsend
-u]/[netreice -u] as Miller suggested.  Mission accomplished.

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