Network: Spawning 2 UDP connections from TCP Rendez vous

Scripting Issues
1

Hello all,
Still struggling with my network code.
Basically, what i need is :
when server receive a connection on the special TCP rendez vous port,

instead of adding the connection (a tcp connection from the client )

 if cListener.newConnectionAvailable():

    rendezvous = PointerToConnection()
    netAddress = NetAddress()
    newConnection = PointerToConnection()

    if cListener.getNewConnection(rendezvous,netAddress,newConnection):
      newConnection = newConnection.p()
      activeConnections.append(newConnection) # Remember connection
      cReader.addConnection(newConnection) # Begin reading connection
  return Task.cont

it creates 2 bi-directionnal UDP connection to the client that requested connection.

ex Client 1 make a TCP Connection to Server .
Server create a UDP connection u1 between port1 of Client 1 and port X1 of server for sending / receiving data
Server create a UDP connection u2 between port2 of Client 1 and port X2 of server for sending / receiving data

Questions:
1)Is it enough to for Client 1 to know server ip and Port X1,X2 to be able to create a u1_c UPD connection that listen and send on the u1 connection? or do i need a kind of handshake ?

  1. how do i create an UPD connection in Panda that can both send and receive packet. Is it enough to create 1 UPD connection and add it both on a QueuedConnectionReader and a QueuedConnectionWriter

  2. Can the connection rendez vous between client and server be initialized via a Client upd connection ? (from my understanding : NO)

Thanks for your input :slight_smile:

2

  1. no udp is connectionless so sending to a port on any computer that is most likey firewalled is just fine.

  2. yes they are bidirectional … i still cant figure out why you need 2 of them

  3. As in client send a UDP packet to server and connection starts? Well that is how they are normally started… Server sending client UDP packets generally don’t work … that is what you propose in 1.

3

Afaik, udp connections are not bidirectional, however you can just try to send a package back to where it came from. Most often this is blocked by a firewall. However most firewalls remember that you sent a package to a ip and allow responses.

Afaik panda3d handles udp connections as a hostadress, each time you send a package it uses the stored connection (hostname/ip & port) to define the recipient.

I might be completely wrong with all i wrote, but thats my experience :wink:

4

So it means that each “packet”/“datagram” knows from which IP and port he cames from?

So it would mean that i could setup one only UPD Port on server to receive from every Client and still be able to dispatch the packet to the right clients afterward?

5

Yes, that’s right. If you receive the packet with a NetDatagram, you can query the NetDatagram to find out where it came from.

David