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# 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 as 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 as 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)', end=' ')
else: print('(DONT)', end=' ')
opt = IAC + WONT
elif c in (WILL, WONT):
if c == WILL: print('(WILL)', end=' ')
else: print('(WONT)', end=' ')
opt = IAC + DONT
else:
print('(command)', ord(c))
elif c == IAC:
iac = 1
print('(IAC)', end=' ')
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()
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