Demo/threads/telnet.py

   1 # Minimal interface to the Internet telnet protocol.
   2 #
   3 # *** modified to use threads ***
   4 #
   5 # It refuses all telnet options and does not recognize any of the other
   6 # telnet commands, but can still be used to connect in line-by-line mode.
   7 # It's also useful to play with a number of other services,
   8 # like time, finger, smtp and even ftp.
   9 #
  10 # Usage: telnet host [port]
  11 #
  12 # The port may be a service name or a decimal port number;
  13 # it defaults to 'telnet'.
  14
  15
  16 import sys, os, time
  17 from socket import *
  18 import thread
  19
  20 BUFSIZE = 8*1024
  21
  22 # Telnet protocol characters
  23
  24 IAC  = chr(255) # Interpret as command
  25 DONT = chr(254)
  26 DO   = chr(253)
  27 WONT = chr(252)
  28 WILL = chr(251)
  29
  30 def main():
  31     if len(sys.argv) < 2:
  32         sys.stderr.write('usage: telnet hostname [port]\n')
  33         sys.exit(2)
  34     host = sys.argv[1]
  35     try:
  36         hostaddr = gethostbyname(host)
  37     except error:
  38         sys.stderr.write(sys.argv[1] + ': bad host name\n')
  39         sys.exit(2)
  40     #
  41     if len(sys.argv) > 2:
  42         servname = sys.argv[2]
  43     else:
  44         servname = 'telnet'
  45     #
  46     if '0' <= servname[:1] <= '9':
  47         port = eval(servname)
  48     else:
  49         try:
  50             port = getservbyname(servname, 'tcp')
  51         except error:
  52             sys.stderr.write(servname + ': bad tcp service name\n')
  53             sys.exit(2)
  54     #
  55     s = socket(AF_INET, SOCK_STREAM)
  56     #
  57     try:
  58         s.connect((host, port))
  59     except error, msg:
  60         sys.stderr.write('connect failed: %r\n' % (msg,))
  61         sys.exit(1)
  62     #
  63     thread.start_new(child, (s,))
  64     parent(s)
  65
  66 def parent(s):
  67     # read socket, write stdout
  68     iac = 0         # Interpret next char as command
  69     opt = ''        # Interpret next char as option
  70     while 1:
  71         data, dummy = s.recvfrom(BUFSIZE)
  72         if not data:
  73             # EOF -- exit
  74             sys.stderr.write( '(Closed by remote host)\n')
  75             sys.exit(1)
  76         cleandata = ''
  77         for c in data:
  78             if opt:
  79                 print ord(c)
  80 ##                              print '(replying: %r)' % (opt+c,)
  81                 s.send(opt + c)
  82                 opt = ''
  83             elif iac:
  84                 iac = 0
  85                 if c == IAC:
  86                     cleandata = cleandata + c
  87                 elif c in (DO, DONT):
  88                     if c == DO: print '(DO)',
  89                     else: print '(DONT)',
  90                     opt = IAC + WONT
  91                 elif c in (WILL, WONT):
  92                     if c == WILL: print '(WILL)',
  93                     else: print '(WONT)',
  94                     opt = IAC + DONT
  95                 else:
  96                     print '(command)', ord(c)
  97             elif c == IAC:
  98                 iac = 1
  99                 print '(IAC)',
 100             else:
 101                 cleandata = cleandata + c
 102         sys.stdout.write(cleandata)
 103         sys.stdout.flush()
 104 ##              print 'Out:', repr(cleandata)
 105
 106 def child(s):
 107     # read stdin, write socket
 108     while 1:
 109         line = sys.stdin.readline()
 110 ##              print 'Got:', repr(line)
 111         if not line: break
 112         s.send(line)
 113
 114 main()