UDP

General Discussion
1

Client code:

from pandac.PandaModules import loadPrcFileData
loadPrcFileData("", "window-type none")
loadPrcFileData("", "client-sleep 0.001")

import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject
from direct.gui.DirectGui import *
from direct.actor.Actor import Actor
from direct.interval.IntervalGlobal import * 
from pandac.PandaModules import * 
from pandac.PandaModules import Camera
from direct.task import Task 
import sys
class PandaUDPClient(DirectObject):
    def __init__(self):
        print "Hello my dog-faced opponents!" #Please excuse this... :p
        self.target = NetAddress()
        self.target.setHost('192.168.254.12',35167)
        self.initNetwork()

    def initNetwork(self):
        self.cManager = ConnectionManager()  
        self.cWriter = ConnectionWriter(self.cManager,0)
        self.connect()
    
    def connect(self):
        self.Connection = self.cManager.openUDPConnection()
        taskMgr.add(self.sendBlast, "sendBlastTask", -39)
    
    def readTask(self,task):
        pass

    def sendBlast(self,task):
        package = NetDatagram()
        package.addString("blast")
        self.cWriter.send(package,self.Connection,self.target)
        #taskMgr.doMethodLater(2,self.sendBlast,"sendBlastTask")
        return Task.done
    
Conn = PandaUDPClient()
run()

Server code:

from pandac.PandaModules import loadPrcFileData
loadPrcFileData("", "window-type none")
loadPrcFileData("", "client-sleep 0.001")

import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject
from pandac.PandaModules import * 
from direct.task import Task 
from direct.distributed.PyDatagram import PyDatagram 
from direct.distributed.PyDatagramIterator import PyDatagramIterator 
import sys
class PandaUDPTest(DirectObject):
    def __init__(self):
        print "PandaUDP Test now starting..."
        self.initNetwork()
    
    def initNetwork(self):
        #self.cManager = ConnectionManager()  
        self.cManager = QueuedConnectionManager()  
        self.cListener = QueuedConnectionListener(self.cManager, 0)
        self.cReader = QueuedConnectionReader(self.cManager, 0)
        #self.cReader = RecentConnectionReader(self.cManager)
        self.cReader.setRawMode(1)
        
        self.cWriter = ConnectionWriter(self.cManager,0)
        self.startServer()
        
    def startServer(self):
        self.udpSocket = self.cManager.openUDPConnection(35167)
        if not self.udpSocket:
            print "WARNING: cannot Create UDP socket connection"
        self.cListener.addConnection(self.udpSocket)
        print 'Number of threads: ', self.cListener.getNumThreads()
        taskMgr.add(self.listenTask,"serverListenTask",-40)
        taskMgr.add(self.readTask,"serverReadTask",-39)
        print "Server started"

    
    def listenTask(self,task):
        if self.cListener.newConnectionAvailable():
            print "New Connection Detected"
        return Task.cont 
    
    def readTask(self,task):
        if self.cReader.dataAvailable():
             print "New data available"
        return Task.cont



Test = PandaUDPTest()
run()

When I run the server code, its fine. But when the client code attempts to send one “Blast” message, the server gets this error:

:net(error): Error when accepting new connection.

And it just loops forever printing that.
Can anyone please help?
(This was based on my other code that uses TCP instead)

2

As long as it’s not read, there is data available…

    def readTask(self,task):
        if self.cReader.dataAvailable():
             print "New data available"
             # read the data...
        return Task.cont
3

hmm… this code outputs the same error, though…

    def readTask(self,task):
        if self.cReader.dataAvailable():
            print "New data available"
            datagram = NetDatagram()
            sender = datagram.getConnection()
            if self.cReader.getData(datagram):
                message = PyDatagramIterator(datagram)
                data = message.getString()
                print data
        return Task.cont

Please correct me!

:Edit:

Treeform pointed out to me yesterday that the error came from this:

void ConnectionListener::
process_incoming_data(SocketInfo *sinfo) {
  Socket_TCP_Listen *socket;
  DCAST_INTO_V(socket, sinfo->get_socket());

  Socket_Address addr;
  Socket_TCP *session = new Socket_TCP;
  if (!socket->GetIncomingConnection(*session, addr)) {
    net_cat.error()
      << "Error when accepting new connection.\n";
    delete session;

  } else {
    NetAddress net_addr(addr);
    net_cat.info()
      << "Received TCP connection from client " << net_addr.get_ip_string()
      << " on port " << sinfo->_connection->get_address().get_port()
      << "\n";

    PT(Connection) new_connection = new Connection(_manager, session);
    if (_manager != (ConnectionManager *)NULL) {
      _manager->new_connection(new_connection);
    }
    connection_opened(sinfo->_connection, net_addr, new_connection);
  }

  finish_socket(sinfo);
}

As I see it, whenever newConnectionAvailable is called, processIncomingData is also called. However, ConnectionListeners are for TCP connections, not for UDP. Thus, when I call self.cListener.newConnectionAvailable(),

:net(error): Error when accepting new connection.

shows up because it expected a TCP message, not a UDP, as I have sent it…

Now, Im wondering how to properly receive a UDP message…

4

UDP is received with a ConnectionReader, not a ConnectionListener. Since UDP is connectionless, there’s no need for TCP’s rendez-vous mechanism to establish a connection, and thus no need for a listener. Just create a ConnectionReader and start reading.

David

5

Also, I have made a simple copy when I was asking my UDP questions, just look up my user name.