mirror of
https://github.com/python/cpython.git
synced 2025-11-04 07:31:38 +00:00
94 lines
2.1 KiB
Python
Executable file
94 lines
2.1 KiB
Python
Executable file
# Send/receive UDP multicast packets.
|
|
# Requires that your OS kernel supports IP multicast.
|
|
# This is built-in on SGI, still optional for most other vendors.
|
|
#
|
|
# Usage:
|
|
# mcast -s (sender)
|
|
# mcast -b (sender, using broadcast instead multicast)
|
|
# mcast (receivers)
|
|
|
|
MYPORT = 8123
|
|
MYGROUP = '225.0.0.250'
|
|
|
|
import sys
|
|
import time
|
|
import struct
|
|
import regsub
|
|
from socket import *
|
|
|
|
|
|
# Main program
|
|
def main():
|
|
flags = sys.argv[1:]
|
|
#
|
|
if flags:
|
|
sender(flags[0])
|
|
else:
|
|
receiver()
|
|
|
|
|
|
# Sender subroutine (only one per local area network)
|
|
def sender(flag):
|
|
s = socket(AF_INET, SOCK_DGRAM)
|
|
if flag == '-b':
|
|
s.setsockopt(SOL_SOCKET, SO_BROADCAST, 1)
|
|
mygroup = '<broadcast>'
|
|
else:
|
|
mygroup = MYGROUP
|
|
ttl = struct.pack('b', 1) # Time-to-live
|
|
s.setsockopt(IPPROTO_IP, IP_MULTICAST_TTL, ttl)
|
|
while 1:
|
|
data = `time.time()`
|
|
## data = data + (1400 - len(data)) * '\0'
|
|
s.sendto(data, (mygroup, MYPORT))
|
|
time.sleep(1)
|
|
|
|
|
|
# Receiver subroutine (as many as you like)
|
|
def receiver():
|
|
# Open and initialize the socket
|
|
s = openmcastsock(MYGROUP, MYPORT)
|
|
#
|
|
# Loop, printing any data we receive
|
|
while 1:
|
|
data, sender = s.recvfrom(1500)
|
|
while data[-1:] == '\0': data = data[:-1] # Strip trailing \0's
|
|
print sender, ':', `data`
|
|
|
|
|
|
# Open a UDP socket, bind it to a port and select a multicast group
|
|
def openmcastsock(group, port):
|
|
# Import modules used only here
|
|
import regsub
|
|
import struct
|
|
#
|
|
# Create a socket
|
|
s = socket(AF_INET, SOCK_DGRAM)
|
|
#
|
|
# Allow multiple copies of this program on one machine
|
|
# (not strictly needed)
|
|
s.setsockopt(SOL_SOCKET, SO_REUSEPORT, 1)
|
|
#
|
|
# Bind it to the port
|
|
s.bind(('', port))
|
|
#
|
|
# Look up multicast group address in name server
|
|
# (doesn't hurt if it is already in ddd.ddd.ddd.ddd format)
|
|
group = gethostbyname(group)
|
|
#
|
|
# Construct binary group address
|
|
bytes = eval(regsub.gsub('\.', ',', group))
|
|
grpaddr = 0
|
|
for byte in bytes: grpaddr = (grpaddr << 8) | byte
|
|
#
|
|
# Construct struct mreq from grpaddr and ifaddr
|
|
ifaddr = INADDR_ANY
|
|
mreq = struct.pack('ll', grpaddr, ifaddr)
|
|
#
|
|
# Add group membership
|
|
s.setsockopt(IPPROTO_IP, IP_ADD_MEMBERSHIP, mreq)
|
|
#
|
|
return s
|
|
|
|
|
|
main()
|