Demo/sockets/udpecho.py

   1 #! /usr/bin/env python
   2
   3 # Client and server for udp (datagram) echo.
   4 #
   5 # Usage: udpecho -s [port]            (to start a server)
   6 # or:    udpecho -c host [port] <file (client)
   7
   8 import sys
   9 from socket import *
  10
  11 ECHO_PORT = 50000 + 7
  12 BUFSIZE = 1024
  13
  14 def main():
  15         if len(sys.argv) < 2:
  16                 usage()
  17         if sys.argv[1] == '-s':
  18                 server()
  19         elif sys.argv[1] == '-c':
  20                 client()
  21         else:
  22                 usage()
  23
  24 def usage():
  25         sys.stdout = sys.stderr
  26         print 'Usage: udpecho -s [port]            (server)'
  27         print 'or:    udpecho -c host [port] <file (client)'
  28         sys.exit(2)
  29
  30 def server():
  31         if len(sys.argv) > 2:
  32                 port = eval(sys.argv[2])
  33         else:
  34                 port = ECHO_PORT
  35         s = socket(AF_INET, SOCK_DGRAM)
  36         s.bind(('', port))
  37         print 'udp echo server ready'
  38         while 1:
  39                 data, addr = s.recvfrom(BUFSIZE)
  40                 print 'server received', `data`, 'from', `addr`
  41                 s.sendto(data, addr)
  42
  43 def client():
  44         if len(sys.argv) < 3:
  45                 usage()
  46         host = sys.argv[2]
  47         if len(sys.argv) > 3:
  48                 port = eval(sys.argv[3])
  49         else:
  50                 port = ECHO_PORT
  51         addr = host, port
  52         s = socket(AF_INET, SOCK_DGRAM)
  53         s.bind(('', 0))
  54         print 'udp echo client ready, reading stdin'
  55         while 1:
  56                 line = sys.stdin.readline()
  57                 if not line:
  58                         break
  59                 s.sendto(line, addr)
  60                 data, fromaddr = s.recvfrom(BUFSIZE)
  61                 print 'client received', `data`, 'from', `fromaddr`
  62
  63 main()