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322 lines
9.0 KiB
Python
Executable File
322 lines
9.0 KiB
Python
Executable File
# A TELNET client class. Based on RFC 854: TELNET Protocol
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# Specification, by J. Postel and J. Reynolds
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# Example:
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#
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# >>> from telnetlib import Telnet
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# >>> tn = Telnet('voorn.cwi.nl', 79) # connect to finger port
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# >>> tn.write('guido\r\n')
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# >>> print tn.read_all()
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# Login name: guido In real life: Guido van Rossum
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# Office: M353, x4127 Home phone: 020-6225521
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# Directory: /ufs/guido Shell: /usr/local/bin/esh
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# On since Oct 28 11:02:16 on ttyq1
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# Project: Multimedia Kernel Systems
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# No Plan.
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# >>>
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#
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# Note that read() won't read until eof -- it just reads some data
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# (but it guarantees to read at least one byte unless EOF is hit).
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#
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# It is possible to pass a Telnet object to select.select() in order
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# to wait until more data is available. Note that in this case,
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# read_eager() may return '' even if there was data on the socket,
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# because the protocol negotiation may have eaten the data.
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# This is why EOFError is needed to distinguish between "no data"
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# and "connection closed" (since the socket also appears ready for
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# reading when it is closed).
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#
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# Bugs:
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# - may hang when connection is slow in the middle of an IAC sequence
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#
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# To do:
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# - option negotiation
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# Imported modules
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import socket
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import select
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import string
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import regsub
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# Tunable parameters
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DEBUGLEVEL = 0
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# Telnet protocol defaults
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TELNET_PORT = 23
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# Telnet protocol characters (don't change)
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IAC = chr(255) # "Interpret As Command"
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DONT = chr(254)
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DO = chr(253)
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WONT = chr(252)
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WILL = chr(251)
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# Telnet interface class
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class Telnet:
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# Constructor
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def __init__(self, host, *args):
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if not args:
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port = TELNET_PORT
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else:
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if len(args) > 1: raise TypeError, 'too many args'
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port = args[0]
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if not port: port = TELNET_PORT
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self.debuglevel = DEBUGLEVEL
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self.host = host
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self.port = port
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self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self.sock.connect((self.host, self.port))
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self.rawq = ''
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self.irawq = 0
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self.cookedq = ''
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self.eof = 0
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# Destructor
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def __del__(self):
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self.close()
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# Debug message
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def msg(self, msg, *args):
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if self.debuglevel > 0:
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print 'Telnet(%s,%d):' % (self.host, self.port), msg % args
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# Set debug level
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def set_debuglevel(self, debuglevel):
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self.debuglevel = debuglevel
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# Explicit close
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def close(self):
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if self.sock:
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self.sock.close()
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self.sock = None
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self.eof = 1
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# Return socket (e.g. for select)
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def get_socket(self):
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return self.sock
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# Return socket's fileno (e.g. for select)
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def fileno(self):
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return self.sock.fileno()
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# Write a string to the socket, doubling any IAC characters
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# Might block if the connection is blocked
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# May raise socket.error if the connection is closed
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def write(self, buffer):
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if IAC in buffer:
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buffer = regsub.gsub(IAC, IAC+IAC, buffer)
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self.sock.send(buffer)
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# The following read_* methods exist:
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# Special case:
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# - read_until() reads until a string is encountered or a timeout is hit
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# These may block:
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# - read_all() reads all data until EOF
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# - read_some() reads at least one byte until EOF
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# These may do I/O but won't block doing it:
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# - read_very_eager() reads all data available on the socket
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# - read_eager() reads either data already queued or some data
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# available on the socket
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# These don't do I/O:
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# - read_lazy() reads all data in the raw queue (processing it first)
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# - read_very_lazy() reads all data in the cooked queue
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# Read until a given string is encountered or until timeout
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# Raise EOFError if connection closed and no cooked data available
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# Return '' if no cooked data available otherwise
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def read_until(self, match, *args):
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if not args:
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timeout = None
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else:
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if len(args) > 1: raise TypeError, 'too many args'
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timeout = args[0]
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n = len(match)
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self.process_rawq()
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i = string.find(self.cookedq, match)
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if i >= 0:
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i = i+n
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buf = self.cookedq[:i]
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self.cookedq = self.cookedq[i:]
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return buf
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s_reply = ([self], [], [])
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s_args = s_reply
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if timeout is not None:
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s_args = s_args + (timeout,)
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while not self.eof and apply(select.select, s_args) == s_reply:
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i = max(0, len(self.cookedq)-n)
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self.fill_rawq()
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self.process_rawq()
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i = string.find(self.cookedq, match, i)
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if i >= 0:
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i = i+n
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buf = self.cookedq[:i]
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self.cookedq = self.cookedq[i:]
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return buf
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return self.read_very_lazy()
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# Read all data until EOF
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# Block until connection closed
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def read_all(self):
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self.process_rawq()
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while not self.eof:
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self.fill_rawq()
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self.process_rawq()
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buf = self.cookedq
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self.cookedq = ''
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return buf
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# Read at least one byte of cooked data unless EOF is hit
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# Return '' if EOF is hit
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# Block if no data is immediately available
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def read_some(self):
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self.process_rawq()
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while not self.cookedq and not self.eof:
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self.fill_rawq()
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self.process_rawq()
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buf = self.cookedq
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self.cookedq = ''
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return buf
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# Read everything that's possible without blocking in I/O (eager)
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# Raise EOFError if connection closed and no cooked data available
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# Return '' if no cooked data available otherwise
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# Don't block unless in the midst of an IAC sequence
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def read_very_eager(self):
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self.process_rawq()
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while not self.eof and self.sock_avail():
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self.fill_rawq()
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self.process_rawq()
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return self.read_very_lazy()
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# Read readily available data
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# Raise EOFError if connection closed and no cooked data available
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# Return '' if no cooked data available otherwise
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# Don't block unless in the midst of an IAC sequence
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def read_eager(self):
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self.process_rawq()
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while not self.cookedq and not self.eof and self.sock_avail():
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self.fill_rawq()
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self.process_rawq()
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return self.read_very_lazy()
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# Process and return data that's already in the queues (lazy)
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# Raise EOFError if connection closed and no data available
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# Return '' if no cooked data available otherwise
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# Don't block unless in the midst of an IAC sequence
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def read_lazy(self):
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self.process_rawq()
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return self.read_very_lazy()
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# Return any data available in the cooked queue (very lazy)
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# Raise EOFError if connection closed and no data available
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# Return '' if no cooked data available otherwise
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# Don't block
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def read_very_lazy(self):
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buf = self.cookedq
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self.cookedq = ''
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if not buf and self.eof and not self.rawq:
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raise EOFError, 'telnet connection closed'
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return buf
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# Transfer from raw queue to cooked queue
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# Set self.eof when connection is closed
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# Don't block unless in the midst of an IAC sequence
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def process_rawq(self):
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buf = ''
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try:
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while self.rawq:
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c = self.rawq_getchar()
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if c != IAC:
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buf = buf + c
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continue
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c = self.rawq_getchar()
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if c == IAC:
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buf = buf + c
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elif c in (DO, DONT):
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opt = self.rawq_getchar()
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self.msg('IAC %s %d', c == DO and 'DO' or 'DONT', ord(c))
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self.sock.send(IAC + WONT + opt)
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elif c in (WILL, WONT):
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opt = self.rawq_getchar()
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self.msg('IAC %s %d',
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c == WILL and 'WILL' or 'WONT', ord(c))
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else:
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self.msg('IAC %s not recognized' % `c`)
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except EOFError: # raised by self.rawq_getchar()
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pass
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self.cookedq = self.cookedq + buf
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# Get next char from raw queue
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# Block if no data is immediately available
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# Raise EOFError when connection is closed
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def rawq_getchar(self):
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if not self.rawq:
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self.fill_rawq()
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if self.eof:
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raise EOFError
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c = self.rawq[self.irawq]
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self.irawq = self.irawq + 1
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if self.irawq >= len(self.rawq):
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self.rawq = ''
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self.irawq = 0
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return c
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# Fill raw queue from exactly one recv() system call
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# Block if no data is immediately available
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# Set self.eof when connection is closed
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def fill_rawq(self):
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if self.irawq >= len(self.rawq):
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self.rawq = ''
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self.irawq = 0
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# The buffer size should be fairly small so as to avoid quadratic
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# behavior in process_rawq() above
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buf = self.sock.recv(50)
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self.eof = (not buf)
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self.rawq = self.rawq + buf
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# Test whether data is available on the socket
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def sock_avail(self):
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return select.select([self], [], [], 0) == ([self], [], [])
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# Test program
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# Usage: test [-d] ... [host [port]]
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def test():
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import sys, string, socket, select
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debuglevel = 0
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while sys.argv[1:] and sys.argv[1] == '-d':
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debuglevel = debuglevel+1
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del sys.argv[1]
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host = 'localhost'
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if sys.argv[1:]:
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host = sys.argv[1]
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port = 0
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if sys.argv[2:]:
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portstr = sys.argv[2]
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try:
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port = string.atoi(portstr)
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except string.atoi_error:
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port = socket.getservbyname(portstr, 'tcp')
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tn = Telnet(host, port)
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tn.set_debuglevel(debuglevel)
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while 1:
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rfd, wfd, xfd = select.select([tn, sys.stdin], [], [])
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if sys.stdin in rfd:
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line = sys.stdin.readline()
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tn.write(line)
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if tn in rfd:
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try:
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text = tn.read_eager()
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except EOFError:
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print '*** Connection closed by remote host ***'
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break
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if text:
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sys.stdout.write(text)
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sys.stdout.flush()
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tn.close()
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