'Deliver response.
Destination is based on topmost Via header.'

def deliverResponse(self, responseMessage):

    destVia = parseViaHeader(responseMessage.headers['via'][0])
    host = (destVia.received or destVia.host)
    port = (destVia.rport or destVia.port or self.PORT)
    destAddr = URL(host=host, port=port)
    self.sendMessage(destAddr, responseMessage)
