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2116b12da5
robust at shutdown. If needs to release multiple resources, they are released even if errors are occured.
670 lines
22 KiB
Python
670 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 a selector in order to wait until
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more data is available. Note that in this case, read_eager() may return b''
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even if there was data on the socket, because the protocol negotiation may have
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eaten the data. This is why EOFError is needed in some cases to distinguish
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between "no data" and "connection closed" (since the socket also appears ready
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for reading 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 selectors
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from time import monotonic as _time
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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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# poll/select have the advantage of not requiring any extra file descriptor,
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# contrarily to epoll/kqueue (also, they require a single syscall).
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if hasattr(selectors, 'PollSelector'):
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_TelnetSelector = selectors.PollSelector
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else:
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_TelnetSelector = selectors.SelectSelector
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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,%s):' % (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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sock = self.sock
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self.sock = None
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self.eof = True
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self.iacseq = b''
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self.sb = 0
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if sock:
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sock.close()
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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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OSError 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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if timeout is not None:
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deadline = _time() + timeout
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with _TelnetSelector() as selector:
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selector.register(self, selectors.EVENT_READ)
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while not self.eof:
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if selector.select(timeout):
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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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timeout = deadline - _time()
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if timeout < 0:
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break
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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)
|
|
self.rawq = self.rawq + buf
|
|
|
|
def sock_avail(self):
|
|
"""Test whether data is available on the socket."""
|
|
with _TelnetSelector() as selector:
|
|
selector.register(self, selectors.EVENT_READ)
|
|
return bool(selector.select(0))
|
|
|
|
def interact(self):
|
|
"""Interaction function, emulates a very dumb telnet client."""
|
|
if sys.platform == "win32":
|
|
self.mt_interact()
|
|
return
|
|
with _TelnetSelector() as selector:
|
|
selector.register(self, selectors.EVENT_READ)
|
|
selector.register(sys.stdin, selectors.EVENT_READ)
|
|
|
|
while True:
|
|
for key, events in selector.select():
|
|
if key.fileobj is self:
|
|
try:
|
|
text = self.read_eager()
|
|
except EOFError:
|
|
print('*** Connection closed by remote host ***')
|
|
return
|
|
if text:
|
|
sys.stdout.write(text.decode('ascii'))
|
|
sys.stdout.flush()
|
|
elif key.fileobj is sys.stdin:
|
|
line = sys.stdin.readline().encode('ascii')
|
|
if not line:
|
|
return
|
|
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.encode('ascii'))
|
|
|
|
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.decode('ascii'))
|
|
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:
|
|
deadline = _time() + timeout
|
|
with _TelnetSelector() as selector:
|
|
selector.register(self, selectors.EVENT_READ)
|
|
while not self.eof:
|
|
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 timeout is not None:
|
|
ready = selector.select(timeout)
|
|
timeout = deadline - _time()
|
|
if not ready:
|
|
if timeout < 0:
|
|
break
|
|
else:
|
|
continue
|
|
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()
|