[Twisted-Python] Getting local UDP address/port

I am implementing a UDP protocol where a request is sent to a server through a connected UDP transport. I listen for the answer using reactor.listenUDP(0, myDatagramProtocol). The local port is not in itself significant (hence the 0), but the protocol require that I get the local IP address and port of the socket used to send the request (so that I can properly process the answser). How can I get this information ? datagramReceived only provides me with the source address and port of the answer (as can be expected). Regards, Olivier.