使用Twisted Python的UDP客户端和服务器
我想用Twisted创建一个服务器和客户端，能够通过网络发送和接收UDP数据包。我之前用Python的套接字写过这个，但现在想利用Twisted的回调和线程功能。不过，我对Twisted的设计还有些不太明白。
我有多种类型的数据包想要接收，但我们先假装只有一种：
class Packet(object):
def __init__(self, data=None):
self.packet_type = 1
self.payload = ''
self.structure = '!H6s'
if data == None:
return
self.packet_type, self.payload = struct.unpack(self.structure, data)
def pack(self):
return struct.pack(self.structure, self.packet_type, self.payload)
def __str__(self):
return "Type: {0}\nPayload {1}\n\n".format(self.packet_type, self.payload)
我做了一个协议类（几乎是例子的直接复制），当我从另一个程序发送数据时，这个类似乎能正常工作：
class MyProtocol(DatagramProtocol):
def datagramReceived(self, data, (host, port)):
p = Packet(data)
print p
reactor.listenUDP(3000, MyProtocol())
reactor.run()
我不太清楚的是，如何创建一个客户端，能够在网络上发送任意的数据包，并且这些数据包能被反应器接收到：
# Something like this:
s = Sender()
p = Packet()
p.packet_type = 3
s.send(p.pack())
p.packet_type = 99
s.send(p.pack())
我还需要确保在客户端和服务器上设置重用地址的标志，这样我就可以在同一设备上同时运行多个实例（比如一个脚本发送心跳，另一个响应心跳等等）。
有没有人能告诉我如何用Twisted做到这一点？
更新：
这是我用Python的套接字实现的方式。我可以同时运行多个监听器和发送器，它们都能互相听到。那我该如何用Twisted实现这个效果呢？（监听部分不需要是一个单独的进程。）
class Listener(Process):
def __init__(self, ip='127.0.0.1', port=3000):
Process.__init__(self)
self.ip = ip
self.port = port
def run(self):
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind((self.ip, self.port))
data, from_ip = sock.recvfrom(4096)
p = Packet(data)
print p
class Sender(object):
def __init__(self, ip='127.255.255.255', port=3000):
self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.ip = (ip, port)
def send(self, data):
self.sock.sendto(data, self.ip)
if __name__ == "__main__":
l = Listener()
l.start()
s = Sender()
p = Packet()
p.packet_type = 4
p.payload = 'jake'
s.send(p.pack())
可行的解决方案：
class MySender(DatagramProtocol):
def __init__(self, packet, host='127.255.255.255', port=3000):
self.packet = packet.pack()
self.host = host
self.port = port
def startProtocol(self):
self.transport.write(self.packet, (self.host, self.port))
if __name__ == "__main__":
packet = Packet()
packet.packet_type = 1
packet.payload = 'jake'
s = MySender(packet)
reactor.listenMulticast(3000, MyProtocol(), listenMultiple=True)
reactor.listenMulticast(3000, s, listenMultiple=True)
reactor.callLater(4, reactor.stop)
reactor.run()
2 个回答
2
可以看看这个echoclient_udp.py的例子。
因为UDP在客户端和服务器之间的工作方式差不多，所以你只需要在那边也运行一下 reactor.listenUDP，然后 connect 到服务器（这其实只是设置了发送数据包的默认目的地），接着用 transport.write 来发送你的数据包。
12
就像上面的服务器示例一样，这里也有一个客户端的示例。这应该能帮助你入门：
- https://twistedmatrix.com/documents/current/core/howto/udp.html
- https://github.com/twisted/twisted/blob/trunk/docs/core/examples/echoclient_udp.py
好的，这里有一个简单的心跳发送器和接收器，使用的是数据报协议。
from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
from twisted.internet.task import LoopingCall
import sys, time
class HeartbeatSender(DatagramProtocol):
def __init__(self, name, host, port):
self.name = name
self.loopObj = None
self.host = host
self.port = port
def startProtocol(self):
# Called when transport is connected
# I am ready to send heart beats
self.loopObj = LoopingCall(self.sendHeartBeat)
self.loopObj.start(2, now=False)
def stopProtocol(self):
"Called after all transport is teared down"
pass
def datagramReceived(self, data, (host, port)):
print "received %r from %s:%d" % (data, host, port)
def sendHeartBeat(self):
self.transport.write(self.name, (self.host, self.port))
class HeartbeatReciever(DatagramProtocol):
def __init__(self):
pass
def startProtocol(self):
"Called when transport is connected"
pass
def stopProtocol(self):
"Called after all transport is teared down"
def datagramReceived(self, data, (host, port)):
now = time.localtime(time.time())
timeStr = str(time.strftime("%y/%m/%d %H:%M:%S",now))
print "received %r from %s:%d at %s" % (data, host, port, timeStr)
heartBeatSenderObj = HeartbeatSender("sender", "127.0.0.1", 8005)
reactor.listenMulticast(8005, HeartbeatReciever(), listenMultiple=True)
reactor.listenMulticast(8005, heartBeatSenderObj, listenMultiple=True)
reactor.run()
广播示例只是对上述方法进行了简单的修改：
from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor
from twisted.internet.task import LoopingCall
import sys, time
class HeartbeatSender(DatagramProtocol):
def __init__(self, name, host, port):
self.name = name
self.loopObj = None
self.host = host
self.port = port
def startProtocol(self):
# Called when transport is connected
# I am ready to send heart beats
self.transport.joinGroup('224.0.0.1')
self.loopObj = LoopingCall(self.sendHeartBeat)
self.loopObj.start(2, now=False)
def stopProtocol(self):
"Called after all transport is teared down"
pass
def datagramReceived(self, data, (host, port)):
print "received %r from %s:%d" % (data, host, port)
def sendHeartBeat(self):
self.transport.write(self.name, (self.host, self.port))
class HeartbeatReciever(DatagramProtocol):
def __init__(self, name):
self.name = name
def startProtocol(self):
"Called when transport is connected"
self.transport.joinGroup('224.0.0.1')
pass
def stopProtocol(self):
"Called after all transport is teared down"
def datagramReceived(self, data, (host, port)):
now = time.localtime(time.time())
timeStr = str(time.strftime("%y/%m/%d %H:%M:%S",now))
print "%s received %r from %s:%d at %s" % (self.name, data, host, port, timeStr)
heartBeatSenderObj = HeartbeatSender("sender", "224.0.0.1", 8005)
reactor.listenMulticast(8005, HeartbeatReciever("listner1"), listenMultiple=True)
reactor.listenMulticast(8005, HeartbeatReciever("listner2"), listenMultiple=True)
reactor.listenMulticast(8005, heartBeatSenderObj, listenMultiple=True)
reactor.run()