Initial commit

Lts/Tools/multicast_receiver.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+
+#
+# @RDE_HEADER@
+# $Id$
+# $HeadURL$
+# $Author$
+# Created by Christian Fröbel, NLE, 2019-08-08
+#
+
+import socket
+import struct
+from contextlib import contextmanager
+from argparse import ArgumentParser, RawDescriptionHelpFormatter
+import sys
+
+# struct in_addr
+# {
+#     uint32_t       s_addr;     /* address in network byte order */
+# };
+
+# struct ip_mreqn
+# {
+#     struct in_addr imr_multiaddr; /* IP multicast group address */
+#     struct in_addr imr_address;   /* IP address of local interface */
+#     int            imr_ifindex;   /* interface index */
+# };
+
+def _createBoundSocket(multicastGroup, multicastPort, interface):
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    
+    s.bind((multicastGroup, multicastPort))
+    
+    mreqn = struct.pack('4s4si', socket.inet_aton(multicastGroup), socket.inet_aton(interface), 0)
+    s.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreqn)
+    
+    return s
+
+
+def _receive(s):
+    while True:
+        buf, address = s.recvfrom(4096)
+        print('received {} bytes from {}'.format(len(buf), address))
+
+
+def _main():
+    args = _parseCmdLine()
+    with autoClose(_createBoundSocket(args.group, args.port, args.interface)) as s:
+        _receive(s)
+
+    
+@contextmanager
+def autoClose(resource):
+    try:
+        yield resource
+    finally:
+        resource.close()
+
+def _parseCmdLine():
+    parser = ArgumentParser(description='Tool to receive multicast traffic', formatter_class=RawDescriptionHelpFormatter)
+    parser.add_argument('--group', '-g', required=True, help='multicast group')
+    parser.add_argument('--port', '-p', type=int, required=True, help='port')
+    parser.add_argument('--interface', '-i', default='0.0.0.0', help='address of interface to listen on; default 0.0.0.0')
+    return parser.parse_args()
+
+if __name__ == '__main__':
+    _main()