I've found an example for UDP broadcasting:
<https://twistedmatrix.com/trac/browser/trunk/docs/projects/core/examples
/udpbroadcast.py?rev=41516>
However, it combines the sender and receiver in a way that I find
confusing. I figured out how output UDP broadcast packets, but not how
to make a client that receives to the packets.
Here is what we have, which doesn't work. Based on a comment on the
broadcast UDP ticket. I suspect the problem is specifying the broadcast
address using the interface argument to listenUDP, but I'm not sure. In
any case, no value for interface that I've tried works:
-"<broadcast>" (which is what my senders uses) results in
twisted.internet.error.InvalidAddressError
-"255.255.255.255" results in twisted.internet.error.CannotListenError:
Couldn't listen on 255.255.255.255:1235: [Errno 49] Can't assign
requested address.
- omitting it results in no packets received.
I also tried listenMulticast, but it didn't work (and I didn't expect it
to, based on comments I saw on the ticket for implementing UDP broadcast
support).
Any hints would be appreciated.
#!/usr/bin/env python2
"""Attempt to listen to UDP broadcasts
"""
from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
Port = 1235
class BroadcastUDPClient(DatagramProtocol):
def startProtocol(self):
self.transport.setBroadcastAllowed(True)
def datagramReceived(self, datagram, address):
print "got a UDP broadcast packet"
class UDPListener(object):
def __init__(self, port):
self.port = port
self.broadcastClient = BroadcastUDPClient()
self.listener = None
self.startListening()
def startListening(self):
if self.listener is None:
interface = "255.255.255.255"
self.listener = reactor.listenUDP(self.port,
self.broadcastClient, interface)
def stopListening(self):
if self.listener is not None:
self.listener.stopListening()
self.listener = None
if __name__ == "__main__":
listener = UDPListener(Port)
reactor.run()
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