# Minimal interface to the Internet telnet protocol.

#

# *** modified to use threads ***

#

# It refuses all telnet options and does not recognize any of the other

# telnet commands, but can still be used to connect in line-by-line mode.

# It's also useful to play with a number of other services,

# like time, finger, smtp and even ftp.

#

# Usage: telnet host [port]

#

# The port may be a service name or a decimal port number;

# it defaults to 'telnet'.

import sys, os, time

from socket import *

import thread

BUFSIZE = 8*1024

# Telnet protocol characters

IAC  = chr(255) # Interpret as command

DONT = chr(254)

DO   = chr(253)

WONT = chr(252)

WILL = chr(251)

def main():

    if len(sys.argv) < 2:

        sys.stderr.write('usage: telnet hostname [port]\n')

        sys.exit(2)

    host = sys.argv[1]

    try:

        hostaddr = gethostbyname(host)

    except error:

        sys.stderr.write(sys.argv[1] + ': bad host name\n')

        sys.exit(2)

    #

    if len(sys.argv) > 2:

        servname = sys.argv[2]

    else:

        servname = 'telnet'

    #

    if '0' <= servname[:1] <= '9':

        port = eval(servname)

    else:

        try:

            port = getservbyname(servname, 'tcp')

        except error:

            sys.stderr.write(servname + ': bad tcp service name\n')

            sys.exit(2)

    #

    s = socket(AF_INET, SOCK_STREAM)

    #

    try:

        s.connect((host, port))

    except error, msg:

        sys.stderr.write('connect failed: %r\n' % (msg,))

        sys.exit(1)

    #

    thread.start_new(child, (s,))

    parent(s)

def parent(s):

    # read socket, write stdout

    iac = 0         # Interpret next char as command

    opt = ''        # Interpret next char as option

    while 1:

        data, dummy = s.recvfrom(BUFSIZE)

        if not data:

            # EOF -- exit

            sys.stderr.write( '(Closed by remote host)\n')

            sys.exit(1)

        cleandata = ''

        for c in data:

            if opt:

                print ord(c)

##                              print '(replying: %r)' % (opt+c,)

                s.send(opt + c)

                opt = ''

            elif iac:

                iac = 0

                if c == IAC:

                    cleandata = cleandata + c

                elif c in (DO, DONT):

                    if c == DO: print '(DO)',

                    else: print '(DONT)',

                    opt = IAC + WONT

                elif c in (WILL, WONT):

                    if c == WILL: print '(WILL)',

                    else: print '(WONT)',

                    opt = IAC + DONT

                else:

                    print '(command)', ord(c)

            elif c == IAC:

                iac = 1

                print '(IAC)',

            else:

                cleandata = cleandata + c

        sys.stdout.write(cleandata)

        sys.stdout.flush()

##              print 'Out:', repr(cleandata)

def child(s):

    # read stdin, write socket

    while 1:

        line = sys.stdin.readline()

##              print 'Got:', repr(line)

        if not line: break

        s.send(line)

main()