| 1 | #! /usr/bin/env python
|
|---|
| 2 |
|
|---|
| 3 | # Minimal interface to the Internet telnet protocol.
|
|---|
| 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, posix, time
|
|---|
| 17 | from socket import *
|
|---|
| 18 |
|
|---|
| 19 | BUFSIZE = 1024
|
|---|
| 20 |
|
|---|
| 21 | # Telnet protocol characters
|
|---|
| 22 |
|
|---|
| 23 | IAC = chr(255) # Interpret as command
|
|---|
| 24 | DONT = chr(254)
|
|---|
| 25 | DO = chr(253)
|
|---|
| 26 | WONT = chr(252)
|
|---|
| 27 | WILL = chr(251)
|
|---|
| 28 |
|
|---|
| 29 | def main():
|
|---|
| 30 | host = sys.argv[1]
|
|---|
| 31 | try:
|
|---|
| 32 | hostaddr = gethostbyname(host)
|
|---|
| 33 | except error:
|
|---|
| 34 | sys.stderr.write(sys.argv[1] + ': bad host name\n')
|
|---|
| 35 | sys.exit(2)
|
|---|
| 36 | #
|
|---|
| 37 | if len(sys.argv) > 2:
|
|---|
| 38 | servname = sys.argv[2]
|
|---|
| 39 | else:
|
|---|
| 40 | servname = 'telnet'
|
|---|
| 41 | #
|
|---|
| 42 | if '0' <= servname[:1] <= '9':
|
|---|
| 43 | port = eval(servname)
|
|---|
| 44 | else:
|
|---|
| 45 | try:
|
|---|
| 46 | port = getservbyname(servname, 'tcp')
|
|---|
| 47 | except error:
|
|---|
| 48 | sys.stderr.write(servname + ': bad tcp service name\n')
|
|---|
| 49 | sys.exit(2)
|
|---|
| 50 | #
|
|---|
| 51 | s = socket(AF_INET, SOCK_STREAM)
|
|---|
| 52 | #
|
|---|
| 53 | try:
|
|---|
| 54 | s.connect((host, port))
|
|---|
| 55 | except error, msg:
|
|---|
| 56 | sys.stderr.write('connect failed: ' + repr(msg) + '\n')
|
|---|
| 57 | sys.exit(1)
|
|---|
| 58 | #
|
|---|
| 59 | pid = posix.fork()
|
|---|
| 60 | #
|
|---|
| 61 | if pid == 0:
|
|---|
| 62 | # child -- read stdin, write socket
|
|---|
| 63 | while 1:
|
|---|
| 64 | line = sys.stdin.readline()
|
|---|
| 65 | s.send(line)
|
|---|
| 66 | else:
|
|---|
| 67 | # parent -- read socket, write stdout
|
|---|
| 68 | iac = 0 # Interpret next char as command
|
|---|
| 69 | opt = '' # Interpret next char as option
|
|---|
| 70 | while 1:
|
|---|
| 71 | data = s.recv(BUFSIZE)
|
|---|
| 72 | if not data:
|
|---|
| 73 | # EOF; kill child and exit
|
|---|
| 74 | sys.stderr.write( '(Closed by remote host)\n')
|
|---|
| 75 | posix.kill(pid, 9)
|
|---|
| 76 | sys.exit(1)
|
|---|
| 77 | cleandata = ''
|
|---|
| 78 | for c in data:
|
|---|
| 79 | if opt:
|
|---|
| 80 | print ord(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 |
|
|---|
| 105 |
|
|---|
| 106 | try:
|
|---|
| 107 | main()
|
|---|
| 108 | except KeyboardInterrupt:
|
|---|
| 109 | pass
|
|---|
