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      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()
    115