.

tmcast.py

+#!/usr/bin/env python
+"""test program to exercise multicast send/receive."""
+
+from __future__ import print_function
+
+
+import sys, struct, time
+from socket import socket, AF_INET, SOCK_DGRAM, IPPROTO_UDP, SOL_SOCKET, \
+    SO_REUSEADDR, IPPROTO_IP, IP_ADD_MEMBERSHIP, IP_MULTICAST_TTL, IP_MULTICAST_LOOP,   \
+    inet_aton, INADDR_ANY
+
+group4 = '224.1.1.1'
+group6 = 'XXX'
+port   =  5678
+
+# open_rx returns function to receive from group:port.
+def open_rx(group, port):
+    # XXX autodetect ip4/ip6 based on group addr
+    sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
+    sk.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
+    sk.bind((group, port))
+
+    mreq = struct.pack("4sl", inet_aton(group), INADDR_ANY)
+    sk.setsockopt(IPPROTO_IP, IP_ADD_MEMBERSHIP, mreq)
+    def _(): # -> data
+        return sk.recv(4096)
+    return _
+
+# open_tx returns function to send to group:port.
+def open_tx(group, port, ttl=2):
+    sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
+    sk.setsockopt(IPPROTO_IP, IP_MULTICAST_TTL, ttl)
+    # XXX IP_MULTICAST_LOOP
+    def _(data):
+        return sk.sendto(data, (group, port))
+    return _
+
+
+def txloop(pkt):
+    tx = open_tx(group4, port)
+    i = 0
+    while 1:
+        i += 1
+        pkt_ = pkt + (b'%d' % i)
+        print("tx: %r ..." % pkt_)
+        tx(pkt + (b'%d' % i))
+        time.sleep(1)
+
+def rxloop():
+    rx = open_rx(group4, port)
+    while 1:
+        pkt = rx()
+        print("rx: %r" % pkt)
+
+
+def main():
+    action = sys.argv[1]
+    if action == "tx":
+        txloop(sys.argv[2])
+    elif action == "rx":
+        rxloop()
+    else:
+        raise RuntimeError("Unknown action %r" % action)
+
+
+
+
+
+if __name__ == '__main__':
+    main()