On 02.06.2021 16:55, Martin Peach wrote:
On Wed, Jun 2, 2021 at 9:58 AM Roman Haefeli <[email protected]> wrote:
(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 <[email protected]>
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
that.
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).
You're correct. I thought I had fixed that a few years back but I
guess I hadn't.
You could still have the server reply to the source port plus one, or
something like that,
This doesn't solve anything regarding firewall + NAT.
Usually I have the client include its replyto port in a message.
But why? UDP sockets are already bidirectional. If you need to receive
replies from the other end, just use the appropriate object, i.e.
[iemnet/udpclient] or [netsend -u -b].
EDIT: I just saw your mail about [mrpeach/udpsndrcv] which probably
achieves the same thing.
<rant> There is some persistent misunderstanding that UDP sockets can
only be used in one direction. I think one reason is that many creative
coding environments only provide very basic and limited networking
objects, so users without a background in network programming think
that's the way it should be done. In the "real world", a UDP server
would simply send the reply to the source IP address + port obtained
with recvfrom() while a TCP server would send its message to the client
socket it received the message from. It's ironic that Pd doesn't provide
an easy way for such a common task... </rant>
I just remembered that I already opened an issue:
https://github.com/pure-data/pure-data/issues/949. Maybe it's time to
also make a PR :-)
Martin
So, I believe my goal can (so far) only be achieved with [netsend
-u]/[netreice -u] as Miller suggested. Mission accomplished.
Roman
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