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657 lines
22 KiB
Python
657 lines
22 KiB
Python
r"""TELNET client class.
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Based on RFC 854: TELNET Protocol Specification, by J. Postel and
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J. Reynolds
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Example:
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>>> from telnetlib import Telnet
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>>> tn = Telnet('www.python.org', 79) # connect to finger port
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>>> tn.write(b'guido\r\n')
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>>> print(tn.read_all())
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Login Name TTY Idle When Where
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guido Guido van Rossum pts/2 <Dec 2 11:10> snag.cnri.reston..
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>>>
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Note that read_all() 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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It is possible to pass a Telnet object to select.select() in order to
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wait until more data is available. Note that in this case,
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read_eager() may return b'' even if there was data on the socket,
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because the protocol negotiation may have eaten the data. This is why
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EOFError is needed in some cases to distinguish between "no data" and
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"connection closed" (since the socket also appears ready for reading
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when it is closed).
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To do:
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- option negotiation
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- timeout should be intrinsic to the connection object instead of an
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option on one of the read calls only
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"""
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# Imported modules
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import sys
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import socket
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import select
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__all__ = ["Telnet"]
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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 = bytes([255]) # "Interpret As Command"
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DONT = bytes([254])
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DO = bytes([253])
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WONT = bytes([252])
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WILL = bytes([251])
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theNULL = bytes([0])
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SE = bytes([240]) # Subnegotiation End
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NOP = bytes([241]) # No Operation
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DM = bytes([242]) # Data Mark
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BRK = bytes([243]) # Break
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IP = bytes([244]) # Interrupt process
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AO = bytes([245]) # Abort output
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AYT = bytes([246]) # Are You There
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EC = bytes([247]) # Erase Character
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EL = bytes([248]) # Erase Line
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GA = bytes([249]) # Go Ahead
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SB = bytes([250]) # Subnegotiation Begin
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# Telnet protocol options code (don't change)
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# These ones all come from arpa/telnet.h
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BINARY = bytes([0]) # 8-bit data path
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ECHO = bytes([1]) # echo
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RCP = bytes([2]) # prepare to reconnect
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SGA = bytes([3]) # suppress go ahead
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NAMS = bytes([4]) # approximate message size
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STATUS = bytes([5]) # give status
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TM = bytes([6]) # timing mark
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RCTE = bytes([7]) # remote controlled transmission and echo
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NAOL = bytes([8]) # negotiate about output line width
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NAOP = bytes([9]) # negotiate about output page size
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NAOCRD = bytes([10]) # negotiate about CR disposition
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NAOHTS = bytes([11]) # negotiate about horizontal tabstops
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NAOHTD = bytes([12]) # negotiate about horizontal tab disposition
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NAOFFD = bytes([13]) # negotiate about formfeed disposition
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NAOVTS = bytes([14]) # negotiate about vertical tab stops
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NAOVTD = bytes([15]) # negotiate about vertical tab disposition
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NAOLFD = bytes([16]) # negotiate about output LF disposition
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XASCII = bytes([17]) # extended ascii character set
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LOGOUT = bytes([18]) # force logout
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BM = bytes([19]) # byte macro
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DET = bytes([20]) # data entry terminal
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SUPDUP = bytes([21]) # supdup protocol
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SUPDUPOUTPUT = bytes([22]) # supdup output
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SNDLOC = bytes([23]) # send location
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TTYPE = bytes([24]) # terminal type
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EOR = bytes([25]) # end or record
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TUID = bytes([26]) # TACACS user identification
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OUTMRK = bytes([27]) # output marking
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TTYLOC = bytes([28]) # terminal location number
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VT3270REGIME = bytes([29]) # 3270 regime
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X3PAD = bytes([30]) # X.3 PAD
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NAWS = bytes([31]) # window size
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TSPEED = bytes([32]) # terminal speed
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LFLOW = bytes([33]) # remote flow control
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LINEMODE = bytes([34]) # Linemode option
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XDISPLOC = bytes([35]) # X Display Location
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OLD_ENVIRON = bytes([36]) # Old - Environment variables
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AUTHENTICATION = bytes([37]) # Authenticate
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ENCRYPT = bytes([38]) # Encryption option
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NEW_ENVIRON = bytes([39]) # New - Environment variables
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# the following ones come from
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# http://www.iana.org/assignments/telnet-options
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# Unfortunately, that document does not assign identifiers
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# to all of them, so we are making them up
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TN3270E = bytes([40]) # TN3270E
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XAUTH = bytes([41]) # XAUTH
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CHARSET = bytes([42]) # CHARSET
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RSP = bytes([43]) # Telnet Remote Serial Port
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COM_PORT_OPTION = bytes([44]) # Com Port Control Option
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SUPPRESS_LOCAL_ECHO = bytes([45]) # Telnet Suppress Local Echo
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TLS = bytes([46]) # Telnet Start TLS
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KERMIT = bytes([47]) # KERMIT
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SEND_URL = bytes([48]) # SEND-URL
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FORWARD_X = bytes([49]) # FORWARD_X
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PRAGMA_LOGON = bytes([138]) # TELOPT PRAGMA LOGON
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SSPI_LOGON = bytes([139]) # TELOPT SSPI LOGON
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PRAGMA_HEARTBEAT = bytes([140]) # TELOPT PRAGMA HEARTBEAT
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EXOPL = bytes([255]) # Extended-Options-List
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NOOPT = bytes([0])
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class Telnet:
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"""Telnet interface class.
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An instance of this class represents a connection to a telnet
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server. The instance is initially not connected; the open()
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method must be used to establish a connection. Alternatively, the
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host name and optional port number can be passed to the
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constructor, too.
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Don't try to reopen an already connected instance.
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This class has many read_*() methods. Note that some of them
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raise EOFError when the end of the connection is read, because
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they can return an empty string for other reasons. See the
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individual doc strings.
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read_until(expected, [timeout])
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Read until the expected string has been seen, or a timeout is
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hit (default is no timeout); may block.
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read_all()
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Read all data until EOF; may block.
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read_some()
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Read at least one byte or EOF; may block.
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read_very_eager()
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Read all data available already queued or on the socket,
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without blocking.
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read_eager()
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Read either data already queued or some data available on the
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socket, without blocking.
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read_lazy()
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Read all data in the raw queue (processing it first), without
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doing any socket I/O.
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read_very_lazy()
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Reads all data in the cooked queue, without doing any socket
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I/O.
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read_sb_data()
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Reads available data between SB ... SE sequence. Don't block.
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set_option_negotiation_callback(callback)
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Each time a telnet option is read on the input flow, this callback
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(if set) is called with the following parameters :
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callback(telnet socket, command, option)
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option will be chr(0) when there is no option.
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No other action is done afterwards by telnetlib.
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"""
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def __init__(self, host=None, port=0,
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timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
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"""Constructor.
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When called without arguments, create an unconnected instance.
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With a hostname argument, it connects the instance; port number
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and timeout are optional.
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"""
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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.timeout = timeout
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self.sock = None
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self.rawq = b''
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self.irawq = 0
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self.cookedq = b''
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self.eof = 0
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self.iacseq = b'' # Buffer for IAC sequence.
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self.sb = 0 # flag for SB and SE sequence.
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self.sbdataq = b''
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self.option_callback = None
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if host is not None:
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self.open(host, port, timeout)
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def open(self, host, port=0, timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
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"""Connect to a host.
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The optional second argument is the port number, which
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defaults to the standard telnet port (23).
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Don't try to reopen an already connected instance.
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"""
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self.eof = 0
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if not port:
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port = TELNET_PORT
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self.host = host
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self.port = port
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self.timeout = timeout
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self.sock = socket.create_connection((host, port), timeout)
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def __del__(self):
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"""Destructor -- close the connection."""
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self.close()
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def msg(self, msg, *args):
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"""Print a debug message, when the debug level is > 0.
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If extra arguments are present, they are substituted in the
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message using the standard string formatting operator.
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"""
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if self.debuglevel > 0:
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print('Telnet(%s,%d):' % (self.host, self.port), end=' ')
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if args:
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print(msg % args)
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else:
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print(msg)
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def set_debuglevel(self, debuglevel):
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"""Set the debug level.
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The higher it is, the more debug output you get (on sys.stdout).
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"""
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self.debuglevel = debuglevel
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def close(self):
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"""Close the connection."""
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if self.sock:
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self.sock.close()
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self.sock = 0
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self.eof = 1
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self.iacseq = b''
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self.sb = 0
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def get_socket(self):
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"""Return the socket object used internally."""
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return self.sock
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def fileno(self):
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"""Return the fileno() of the socket object used internally."""
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return self.sock.fileno()
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def write(self, buffer):
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"""Write a string to the socket, doubling any IAC characters.
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Can block if the connection is blocked. May raise
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socket.error if the connection is closed.
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"""
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if IAC in buffer:
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buffer = buffer.replace(IAC, IAC+IAC)
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self.msg("send %r", buffer)
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self.sock.sendall(buffer)
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def read_until(self, match, timeout=None):
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"""Read until a given string is encountered or until timeout.
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When no match is found, return whatever is available instead,
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possibly the empty string. Raise EOFError if the connection
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is closed and no cooked data is available.
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"""
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n = len(match)
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self.process_rawq()
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i = self.cookedq.find(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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from time import time
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time_start = time()
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while not self.eof and 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 = self.cookedq.find(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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if timeout is not None:
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elapsed = time() - time_start
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if elapsed >= timeout:
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break
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s_args = s_reply + (timeout-elapsed,)
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return self.read_very_lazy()
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def read_all(self):
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"""Read all data until EOF; block until connection closed."""
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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 = b''
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return buf
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def read_some(self):
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"""Read at least one byte of cooked data unless EOF is hit.
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Return b'' if EOF is hit. Block if no data is immediately
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available.
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"""
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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 = b''
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return buf
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def read_very_eager(self):
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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
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available. Return b'' 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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"""
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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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def read_eager(self):
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"""Read readily available data.
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Raise EOFError if connection closed and no cooked data
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available. Return b'' 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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"""
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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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def read_lazy(self):
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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 b'' if no cooked data available otherwise. Don't block
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unless in the midst of an IAC sequence.
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"""
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self.process_rawq()
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return self.read_very_lazy()
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def read_very_lazy(self):
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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 b'' if no cooked data available otherwise. Don't block.
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"""
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buf = self.cookedq
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self.cookedq = b''
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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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def read_sb_data(self):
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"""Return any data available in the SB ... SE queue.
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Return b'' if no SB ... SE available. Should only be called
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after seeing a SB or SE command. When a new SB command is
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found, old unread SB data will be discarded. Don't block.
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"""
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buf = self.sbdataq
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self.sbdataq = b''
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return buf
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def set_option_negotiation_callback(self, callback):
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"""Provide a callback function called after each receipt of a telnet option."""
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self.option_callback = callback
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def process_rawq(self):
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"""Transfer from raw queue to cooked queue.
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Set self.eof when connection is closed. Don't block unless in
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the midst of an IAC sequence.
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"""
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buf = [b'', b'']
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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 not self.iacseq:
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if c == theNULL:
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continue
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if c == b"\021":
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continue
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if c != IAC:
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buf[self.sb] = buf[self.sb] + c
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continue
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else:
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self.iacseq += c
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elif len(self.iacseq) == 1:
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# 'IAC: IAC CMD [OPTION only for WILL/WONT/DO/DONT]'
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if c in (DO, DONT, WILL, WONT):
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self.iacseq += c
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continue
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self.iacseq = b''
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if c == IAC:
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buf[self.sb] = buf[self.sb] + c
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else:
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if c == SB: # SB ... SE start.
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self.sb = 1
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self.sbdataq = b''
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elif c == SE:
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self.sb = 0
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self.sbdataq = self.sbdataq + buf[1]
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buf[1] = b''
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if self.option_callback:
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# Callback is supposed to look into
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# the sbdataq
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self.option_callback(self.sock, c, NOOPT)
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else:
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# We can't offer automatic processing of
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# suboptions. Alas, we should not get any
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# unless we did a WILL/DO before.
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self.msg('IAC %d not recognized' % ord(c))
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elif len(self.iacseq) == 2:
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cmd = self.iacseq[1:2]
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self.iacseq = b''
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opt = c
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if cmd in (DO, DONT):
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self.msg('IAC %s %d',
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cmd == DO and 'DO' or 'DONT', ord(opt))
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if self.option_callback:
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self.option_callback(self.sock, cmd, opt)
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else:
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self.sock.sendall(IAC + WONT + opt)
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elif cmd in (WILL, WONT):
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self.msg('IAC %s %d',
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cmd == WILL and 'WILL' or 'WONT', ord(opt))
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if self.option_callback:
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self.option_callback(self.sock, cmd, opt)
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else:
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self.sock.sendall(IAC + DONT + opt)
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except EOFError: # raised by self.rawq_getchar()
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self.iacseq = b'' # Reset on EOF
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self.sb = 0
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pass
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self.cookedq = self.cookedq + buf[0]
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self.sbdataq = self.sbdataq + buf[1]
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def rawq_getchar(self):
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"""Get next char from raw queue.
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Block if no data is immediately available. Raise EOFError
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when connection is closed.
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"""
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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:self.irawq+1]
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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 = b''
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self.irawq = 0
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return c
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def fill_rawq(self):
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"""Fill raw queue from exactly one recv() system call.
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Block if no data is immediately available. Set self.eof when
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connection is closed.
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"""
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if self.irawq >= len(self.rawq):
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self.rawq = b''
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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.msg("recv %r", buf)
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self.eof = (not buf)
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self.rawq = self.rawq + buf
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def sock_avail(self):
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"""Test whether data is available on the socket."""
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return select.select([self], [], [], 0) == ([self], [], [])
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def interact(self):
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"""Interaction function, emulates a very dumb telnet client."""
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|
if sys.platform == "win32":
|
|
self.mt_interact()
|
|
return
|
|
while 1:
|
|
rfd, wfd, xfd = select.select([self, sys.stdin], [], [])
|
|
if self in rfd:
|
|
try:
|
|
text = self.read_eager()
|
|
except EOFError:
|
|
print('*** Connection closed by remote host ***')
|
|
break
|
|
if text:
|
|
sys.stdout.write(text.decode('ascii'))
|
|
sys.stdout.flush()
|
|
if sys.stdin in rfd:
|
|
line = sys.stdin.readline().encode('ascii')
|
|
if not line:
|
|
break
|
|
self.write(line)
|
|
|
|
def mt_interact(self):
|
|
"""Multithreaded version of interact()."""
|
|
import _thread
|
|
_thread.start_new_thread(self.listener, ())
|
|
while 1:
|
|
line = sys.stdin.readline()
|
|
if not line:
|
|
break
|
|
self.write(line)
|
|
|
|
def listener(self):
|
|
"""Helper for mt_interact() -- this executes in the other thread."""
|
|
while 1:
|
|
try:
|
|
data = self.read_eager()
|
|
except EOFError:
|
|
print('*** Connection closed by remote host ***')
|
|
return
|
|
if data:
|
|
sys.stdout.write(data)
|
|
else:
|
|
sys.stdout.flush()
|
|
|
|
def expect(self, list, timeout=None):
|
|
"""Read until one from a list of a regular expressions matches.
|
|
|
|
The first argument is a list of regular expressions, either
|
|
compiled (re.RegexObject instances) or uncompiled (strings).
|
|
The optional second argument is a timeout, in seconds; default
|
|
is no timeout.
|
|
|
|
Return a tuple of three items: the index in the list of the
|
|
first regular expression that matches; the match object
|
|
returned; and the text read up till and including the match.
|
|
|
|
If EOF is read and no text was read, raise EOFError.
|
|
Otherwise, when nothing matches, return (-1, None, text) where
|
|
text is the text received so far (may be the empty string if a
|
|
timeout happened).
|
|
|
|
If a regular expression ends with a greedy match (e.g. '.*')
|
|
or if more than one expression can match the same input, the
|
|
results are undeterministic, and may depend on the I/O timing.
|
|
|
|
"""
|
|
re = None
|
|
list = list[:]
|
|
indices = range(len(list))
|
|
for i in indices:
|
|
if not hasattr(list[i], "search"):
|
|
if not re: import re
|
|
list[i] = re.compile(list[i])
|
|
if timeout is not None:
|
|
from time import time
|
|
time_start = time()
|
|
while 1:
|
|
self.process_rawq()
|
|
for i in indices:
|
|
m = list[i].search(self.cookedq)
|
|
if m:
|
|
e = m.end()
|
|
text = self.cookedq[:e]
|
|
self.cookedq = self.cookedq[e:]
|
|
return (i, m, text)
|
|
if self.eof:
|
|
break
|
|
if timeout is not None:
|
|
elapsed = time() - time_start
|
|
if elapsed >= timeout:
|
|
break
|
|
s_args = ([self.fileno()], [], [], timeout-elapsed)
|
|
r, w, x = select.select(*s_args)
|
|
if not r:
|
|
break
|
|
self.fill_rawq()
|
|
text = self.read_very_lazy()
|
|
if not text and self.eof:
|
|
raise EOFError
|
|
return (-1, None, text)
|
|
|
|
|
|
def test():
|
|
"""Test program for telnetlib.
|
|
|
|
Usage: python telnetlib.py [-d] ... [host [port]]
|
|
|
|
Default host is localhost; default port is 23.
|
|
|
|
"""
|
|
debuglevel = 0
|
|
while sys.argv[1:] and sys.argv[1] == '-d':
|
|
debuglevel = debuglevel+1
|
|
del sys.argv[1]
|
|
host = 'localhost'
|
|
if sys.argv[1:]:
|
|
host = sys.argv[1]
|
|
port = 0
|
|
if sys.argv[2:]:
|
|
portstr = sys.argv[2]
|
|
try:
|
|
port = int(portstr)
|
|
except ValueError:
|
|
port = socket.getservbyname(portstr, 'tcp')
|
|
tn = Telnet()
|
|
tn.set_debuglevel(debuglevel)
|
|
tn.open(host, port, timeout=0.5)
|
|
tn.interact()
|
|
tn.close()
|
|
|
|
if __name__ == '__main__':
|
|
test()
|