tests/topotests/lib/mcast-tester.py

   1 #!/usr/bin/env python3
   2 #
   3 # Copyright (C) 2021 by
   4 # Network Device Education Foundation, Inc. ("NetDEF")
   5 #
   6 # Permission to use, copy, modify, and/or distribute this software for any
   7 # purpose with or without fee is hereby granted, provided that the above
   8 # copyright notice and this permission notice appear in all copies.
   9 #
  10 # THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
  11 # REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  12 # AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
  13 # INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  14 # LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
  15 # OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  16 # PERFORMANCE OF THIS SOFTWARE.
  17
  18 """
  19 Subscribe to a multicast group so that the kernel sends an IGMP JOIN
  20 for the multicast group we subscribed to.
  21 """
  22
  23 import argparse
  24 import json
  25 import os
  26 import socket
  27 import struct
  28 import subprocess
  29 import sys
  30 import time
  31
  32
  33 #
  34 # Functions
  35 #
  36 def interface_name_to_index(name):
  37     "Gets the interface index using its name. Returns None on failure."
  38     interfaces = json.loads(subprocess.check_output("ip -j link show", shell=True))
  39
  40     for interface in interfaces:
  41         if interface["ifname"] == name:
  42             return interface["ifindex"]
  43
  44     return None
  45
  46
  47 def multicast_join(sock, ifindex, group, port):
  48     "Joins a multicast group."
  49     mreq = struct.pack(
  50         "=4sLL", socket.inet_aton(args.group), socket.INADDR_ANY, ifindex
  51     )
  52
  53     sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
  54     sock.bind((group, port))
  55     sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
  56
  57
  58 #
  59 # Main code.
  60 #
  61 parser = argparse.ArgumentParser(description="Multicast RX utility")
  62 parser.add_argument("group", help="Multicast IP")
  63 parser.add_argument("interface", help="Interface name")
  64 parser.add_argument("--socket", help="Point to topotest UNIX socket")
  65 parser.add_argument(
  66     "--send", help="Transmit instead of join with interval", type=float, default=0
  67 )
  68 args = parser.parse_args()
  69
  70 ttl = 16
  71 port = 1000
  72
  73 # Get interface index/validate.
  74 ifindex = interface_name_to_index(args.interface)
  75 if ifindex is None:
  76     sys.stderr.write("Interface {} does not exists\n".format(args.interface))
  77     sys.exit(1)
  78
  79 # We need root privileges to set up multicast.
  80 if os.geteuid() != 0:
  81     sys.stderr.write("ERROR: You must have root privileges\n")
  82     sys.exit(1)
  83
  84 # Wait for topotest to synchronize with us.
  85 if not args.socket:
  86     toposock = None
  87 else:
  88     toposock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM, 0)
  89     while True:
  90         try:
  91             toposock.connect(args.socket)
  92             break
  93         except ConnectionRefusedError:
  94             time.sleep(1)
  95             continue
  96     # Set topotest socket non blocking so we can multiplex the main loop.
  97     toposock.setblocking(False)
  98
  99 msock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
 100 if args.send > 0:
 101     # Prepare multicast bit in that interface.
 102     msock.setsockopt(
 103         socket.SOL_SOCKET,
 104         25,
 105         struct.pack("%ds" % len(args.interface), args.interface.encode("utf-8")),
 106     )
 107     # Set packets TTL.
 108     msock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, struct.pack("b", ttl))
 109     # Block to ensure packet send.
 110     msock.setblocking(True)
 111 else:
 112     multicast_join(msock, ifindex, args.group, port)
 113
 114
 115 def should_exit():
 116     if not toposock:
 117         # If we are sending then we have slept
 118         if not args.send:
 119             time.sleep(100)
 120         return False
 121     else:
 122         try:
 123             data = toposock.recv(1)
 124             if data == b"":
 125                 print(" -> Connection closed")
 126                 return True
 127         except BlockingIOError:
 128             return False
 129
 130
 131 counter = 0
 132 while not should_exit():
 133     if args.send > 0:
 134         msock.sendto(b"test %d" % counter, (args.group, port))
 135         counter += 1
 136         time.sleep(args.send)
 137
 138 msock.close()
 139 sys.exit(0)