你如何在Python中UDP多播？

如何在Python中发送和接收UDP多播？有标准库吗？

1> Gordon Wrigl..：

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这对我有用:

接收

import socket
import struct

MCAST_GRP = '224.1.1.1'
MCAST_PORT = 5007
IS_ALL_GROUPS = True

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
if IS_ALL_GROUPS:
    # on this port, receives ALL multicast groups
    sock.bind(('', MCAST_PORT))
else:
    # on this port, listen ONLY to MCAST_GRP
    sock.bind((MCAST_GRP, MCAST_PORT))
mreq = struct.pack("4sl", socket.inet_aton(MCAST_GRP), socket.INADDR_ANY)

sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)

while True:
  print sock.recv(10240)

发送

import socket

MCAST_GRP = '224.1.1.1'
MCAST_PORT = 5007
# regarding socket.IP_MULTICAST_TTL
# ---------------------------------
# for all packets sent, after two hops on the network the packet will not 
# be re-sent/broadcast (see https://www.tldp.org/HOWTO/Multicast-HOWTO-6.html)
MULTICAST_TTL = 2

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, MULTICAST_TTL)
sock.sendto("robot", (MCAST_GRP, MCAST_PORT))

它基于http://wiki.python.org/moin/UdpCommunication中不起作用的示例.

我的系统是... Linux 2.6.31-15-generic#50-Ubuntu SMP Tue 11月10日14:54:29 UTC 2009 i686 GNU/Linux Python 2.6.4

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对于mac os x,您需要使用socket.SO_REUSEPORT选项作为上例中socket.SO_REUSEADDR的替代选项,以允许同一多播端口地址组合上的多个侦听器.

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对于udp多播,你需要绑定到多播组/端口而不是本地组端口,`sock.bind((MCAST_GRP,MCAST_PORT))`,你的代码可能也可能不起作用,当你有多个网络时它可能不起作用

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@RandallCook:当我用MCAST_GRP替换''时,我得到socket.error:[Errno 10049]请求的地址在其上下文中无效

2> 小智..：

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广播到组播组的组播发送方:

#!/usr/bin/env python

import socket
import struct

def main():
  MCAST_GRP = '224.1.1.1'
  MCAST_PORT = 5007
  sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
  sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 32)
  sock.sendto('Hello World!', (MCAST_GRP, MCAST_PORT))

if __name__ == '__main__':
  main()

从多播组读取并将十六进制数据打印到控制台的多播接收器:

#!/usr/bin/env python

import socket
import binascii

def main():
  MCAST_GRP = '224.1.1.1' 
  MCAST_PORT = 5007
  sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
  try:
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
  except AttributeError:
    pass
  sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 32) 
  sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_LOOP, 1)

  sock.bind((MCAST_GRP, MCAST_PORT))
  host = socket.gethostbyname(socket.gethostname())
  sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton(host))
  sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP, 
                   socket.inet_aton(MCAST_GRP) + socket.inet_aton(host))

  while 1:
    try:
      data, addr = sock.recvfrom(1024)
    except socket.error, e:
      print 'Expection'
      hexdata = binascii.hexlify(data)
      print 'Data = %s' % hexdata

if __name__ == '__main__':
  main()

3> st0ne..：

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更好用:

sock.bind((MCAST_GRP, MCAST_PORT))

代替:

sock.bind(('', MCAST_PORT))

因为,如果要在同一端口上侦听多个多播组,您将获得所有侦听器上的所有消息.