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- # -*- test-case-name: twisted.conch.test.test_telnet -*-
- # Copyright (c) Twisted Matrix Laboratories.
- # See LICENSE for details.
-
- """
- Telnet protocol implementation.
-
- @author: Jean-Paul Calderone
- """
-
-
- import struct
-
- from zope.interface import implementer
-
- from twisted.internet import defer, interfaces as iinternet, protocol
- from twisted.logger import Logger
- from twisted.python.compat import iterbytes
-
-
- def _chr(i: int) -> bytes:
- """Create a byte sequence of length 1.
-
- U{RFC 854<https://tools.ietf.org/html/rfc854>} specifies codes in decimal,
- but Python can only handle L{bytes} literals in octal or hexadecimal.
- This helper function bridges that gap.
-
- @param i: The value of the only byte in the sequence.
- """
- return bytes((i,))
-
-
- MODE = _chr(1)
- EDIT = 1
- TRAPSIG = 2
- MODE_ACK = 4
- SOFT_TAB = 8
- LIT_ECHO = 16
-
- # Characters gleaned from the various (and conflicting) RFCs. Not all of these
- # are correct.
-
- NULL = _chr(0) # No operation.
- BEL = _chr(7) # Produces an audible or visible signal (which does NOT move the
- # print head).
- BS = _chr(8) # Moves the print head one character position towards the left
- # margin.
- HT = _chr(9) # Moves the printer to the next horizontal tab stop. It remains
- # unspecified how either party determines or establishes where such tab stops
- # are located.
- LF = _chr(10) # Moves the printer to the next print line, keeping the same
- # horizontal position.
- VT = _chr(11) # Moves the printer to the next vertical tab stop. It remains
- # unspecified how either party determines or establishes where such tab stops
- # are located.
- FF = _chr(12) # Moves the printer to the top of the next page, keeping the same
- # horizontal position.
- CR = _chr(13) # Moves the printer to the left margin of the current line.
-
- ECHO = _chr(1) # User-to-Server: Asks the server to send Echos of the
- # transmitted data.
- SGA = _chr(3) # Suppress Go Ahead. Go Ahead is silly and most modern servers
- # should suppress it.
- NAWS = _chr(31) # Negotiate About Window Size. Indicate that information about
- # the size of the terminal can be communicated.
- LINEMODE = _chr(34) # Allow line buffering to be negotiated about.
-
- EOR = _chr(239) # End of Record (RFC 885)
- SE = _chr(240) # End of subnegotiation parameters.
- NOP = _chr(241) # No operation.
- DM = _chr(242) # "Data Mark": The data stream portion of a Synch. This should
- # always be accompanied by a TCP Urgent notification.
- BRK = _chr(243) # NVT character Break.
- IP = _chr(244) # The function Interrupt Process.
- AO = _chr(245) # The function Abort Output
- AYT = _chr(246) # The function Are You There.
- EC = _chr(247) # The function Erase Character.
- EL = _chr(248) # The function Erase Line
- GA = _chr(249) # The Go Ahead signal.
- SB = _chr(250) # Indicates that what follows is subnegotiation of the indicated
- # option.
- WILL = _chr(251) # Indicates the desire to begin performing, or confirmation
- # that you are now performing, the indicated option.
- WONT = _chr(252) # Indicates the refusal to perform, or continue performing,
- # the indicated option.
- DO = _chr(253) # Indicates the request that the other party perform, or
- # confirmation that you are expecting the other party to perform, the indicated
- # option.
- DONT = _chr(254) # Indicates the demand that the other party stop performing,
- # or confirmation that you are no longer expecting the other party to perform,
- # the indicated option.
- IAC = _chr(255) # Data Byte 255. Introduces a telnet command.
-
- LINEMODE_MODE = _chr(1)
- LINEMODE_EDIT = _chr(1)
- LINEMODE_TRAPSIG = _chr(2)
- LINEMODE_MODE_ACK = _chr(4)
- LINEMODE_SOFT_TAB = _chr(8)
- LINEMODE_LIT_ECHO = _chr(16)
- LINEMODE_FORWARDMASK = _chr(2)
- LINEMODE_SLC = _chr(3)
- LINEMODE_SLC_SYNCH = _chr(1)
- LINEMODE_SLC_BRK = _chr(2)
- LINEMODE_SLC_IP = _chr(3)
- LINEMODE_SLC_AO = _chr(4)
- LINEMODE_SLC_AYT = _chr(5)
- LINEMODE_SLC_EOR = _chr(6)
- LINEMODE_SLC_ABORT = _chr(7)
- LINEMODE_SLC_EOF = _chr(8)
- LINEMODE_SLC_SUSP = _chr(9)
- LINEMODE_SLC_EC = _chr(10)
- LINEMODE_SLC_EL = _chr(11)
-
- LINEMODE_SLC_EW = _chr(12)
- LINEMODE_SLC_RP = _chr(13)
- LINEMODE_SLC_LNEXT = _chr(14)
- LINEMODE_SLC_XON = _chr(15)
- LINEMODE_SLC_XOFF = _chr(16)
- LINEMODE_SLC_FORW1 = _chr(17)
- LINEMODE_SLC_FORW2 = _chr(18)
- LINEMODE_SLC_MCL = _chr(19)
- LINEMODE_SLC_MCR = _chr(20)
- LINEMODE_SLC_MCWL = _chr(21)
- LINEMODE_SLC_MCWR = _chr(22)
- LINEMODE_SLC_MCBOL = _chr(23)
- LINEMODE_SLC_MCEOL = _chr(24)
- LINEMODE_SLC_INSRT = _chr(25)
- LINEMODE_SLC_OVER = _chr(26)
- LINEMODE_SLC_ECR = _chr(27)
- LINEMODE_SLC_EWR = _chr(28)
- LINEMODE_SLC_EBOL = _chr(29)
- LINEMODE_SLC_EEOL = _chr(30)
-
- LINEMODE_SLC_DEFAULT = _chr(3)
- LINEMODE_SLC_VALUE = _chr(2)
- LINEMODE_SLC_CANTCHANGE = _chr(1)
- LINEMODE_SLC_NOSUPPORT = _chr(0)
- LINEMODE_SLC_LEVELBITS = _chr(3)
-
- LINEMODE_SLC_ACK = _chr(128)
- LINEMODE_SLC_FLUSHIN = _chr(64)
- LINEMODE_SLC_FLUSHOUT = _chr(32)
- LINEMODE_EOF = _chr(236)
- LINEMODE_SUSP = _chr(237)
- LINEMODE_ABORT = _chr(238)
-
-
- class ITelnetProtocol(iinternet.IProtocol):
- def unhandledCommand(command, argument):
- """
- A command was received but not understood.
-
- @param command: the command received.
- @type command: L{str}, a single character.
- @param argument: the argument to the received command.
- @type argument: L{str}, a single character, or None if the command that
- was unhandled does not provide an argument.
- """
-
- def unhandledSubnegotiation(command, data):
- """
- A subnegotiation command was received but not understood.
-
- @param command: the command being subnegotiated. That is, the first
- byte after the SB command.
- @type command: L{str}, a single character.
- @param data: all other bytes of the subneogation. That is, all but the
- first bytes between SB and SE, with IAC un-escaping applied.
- @type data: L{bytes}, each a single character
- """
-
- def enableLocal(option):
- """
- Enable the given option locally.
-
- This should enable the given option on this side of the
- telnet connection and return True. If False is returned,
- the option will be treated as still disabled and the peer
- will be notified.
-
- @param option: the option to be enabled.
- @type option: L{bytes}, a single character.
- """
-
- def enableRemote(option):
- """
- Indicate whether the peer should be allowed to enable this option.
-
- Returns True if the peer should be allowed to enable this option,
- False otherwise.
-
- @param option: the option to be enabled.
- @type option: L{bytes}, a single character.
- """
-
- def disableLocal(option):
- """
- Disable the given option locally.
-
- Unlike enableLocal, this method cannot fail. The option must be
- disabled.
-
- @param option: the option to be disabled.
- @type option: L{bytes}, a single character.
- """
-
- def disableRemote(option):
- """
- Indicate that the peer has disabled this option.
-
- @param option: the option to be disabled.
- @type option: L{bytes}, a single character.
- """
-
-
- class ITelnetTransport(iinternet.ITransport):
- def do(option):
- """
- Indicate a desire for the peer to begin performing the given option.
-
- Returns a Deferred that fires with True when the peer begins performing
- the option, or fails with L{OptionRefused} when the peer refuses to
- perform it. If the peer is already performing the given option, the
- Deferred will fail with L{AlreadyEnabled}. If a negotiation regarding
- this option is already in progress, the Deferred will fail with
- L{AlreadyNegotiating}.
-
- Note: It is currently possible that this Deferred will never fire,
- if the peer never responds, or if the peer believes the option to
- already be enabled.
- """
-
- def dont(option):
- """
- Indicate a desire for the peer to cease performing the given option.
-
- Returns a Deferred that fires with True when the peer ceases performing
- the option. If the peer is not performing the given option, the
- Deferred will fail with L{AlreadyDisabled}. If negotiation regarding
- this option is already in progress, the Deferred will fail with
- L{AlreadyNegotiating}.
-
- Note: It is currently possible that this Deferred will never fire,
- if the peer never responds, or if the peer believes the option to
- already be disabled.
- """
-
- def will(option):
- """
- Indicate our willingness to begin performing this option locally.
-
- Returns a Deferred that fires with True when the peer agrees to allow us
- to begin performing this option, or fails with L{OptionRefused} if the
- peer refuses to allow us to begin performing it. If the option is
- already enabled locally, the Deferred will fail with L{AlreadyEnabled}.
- If negotiation regarding this option is already in progress, the
- Deferred will fail with L{AlreadyNegotiating}.
-
- Note: It is currently possible that this Deferred will never fire,
- if the peer never responds, or if the peer believes the option to
- already be enabled.
- """
-
- def wont(option):
- """
- Indicate that we will stop performing the given option.
-
- Returns a Deferred that fires with True when the peer acknowledges
- we have stopped performing this option. If the option is already
- disabled locally, the Deferred will fail with L{AlreadyDisabled}.
- If negotiation regarding this option is already in progress,
- the Deferred will fail with L{AlreadyNegotiating}.
-
- Note: It is currently possible that this Deferred will never fire,
- if the peer never responds, or if the peer believes the option to
- already be disabled.
- """
-
- def requestNegotiation(about, data):
- """
- Send a subnegotiation request.
-
- @param about: A byte indicating the feature being negotiated.
- @param data: Any number of L{bytes} containing specific information
- about the negotiation being requested. No values in this string
- need to be escaped, as this function will escape any value which
- requires it.
- """
-
-
- class TelnetError(Exception):
- pass
-
-
- class NegotiationError(TelnetError):
- def __str__(self) -> str:
- return (
- self.__class__.__module__
- + "."
- + self.__class__.__name__
- + ":"
- + repr(self.args[0])
- )
-
-
- class OptionRefused(NegotiationError):
- pass
-
-
- class AlreadyEnabled(NegotiationError):
- pass
-
-
- class AlreadyDisabled(NegotiationError):
- pass
-
-
- class AlreadyNegotiating(NegotiationError):
- pass
-
-
- @implementer(ITelnetProtocol)
- class TelnetProtocol(protocol.Protocol):
- _log = Logger()
-
- def unhandledCommand(self, command, argument):
- pass
-
- def unhandledSubnegotiation(self, command, data):
- pass
-
- def enableLocal(self, option):
- pass
-
- def enableRemote(self, option):
- pass
-
- def disableLocal(self, option):
- pass
-
- def disableRemote(self, option):
- pass
-
-
- class Telnet(protocol.Protocol):
- """
- @ivar commandMap: A mapping of bytes to callables. When a
- telnet command is received, the command byte (the first byte
- after IAC) is looked up in this dictionary. If a callable is
- found, it is invoked with the argument of the command, or None
- if the command takes no argument. Values should be added to
- this dictionary if commands wish to be handled. By default,
- only WILL, WONT, DO, and DONT are handled. These should not
- be overridden, as this class handles them correctly and
- provides an API for interacting with them.
-
- @ivar negotiationMap: A mapping of bytes to callables. When
- a subnegotiation command is received, the command byte (the
- first byte after SB) is looked up in this dictionary. If
- a callable is found, it is invoked with the argument of the
- subnegotiation. Values should be added to this dictionary if
- subnegotiations are to be handled. By default, no values are
- handled.
-
- @ivar options: A mapping of option bytes to their current
- state. This state is likely of little use to user code.
- Changes should not be made to it.
-
- @ivar state: A string indicating the current parse state. It
- can take on the values "data", "escaped", "command", "newline",
- "subnegotiation", and "subnegotiation-escaped". Changes
- should not be made to it.
-
- @ivar transport: This protocol's transport object.
- """
-
- # One of a lot of things
- state = "data"
-
- def __init__(self):
- self.options = {}
- self.negotiationMap = {}
- self.commandMap = {
- WILL: self.telnet_WILL,
- WONT: self.telnet_WONT,
- DO: self.telnet_DO,
- DONT: self.telnet_DONT,
- }
-
- def _write(self, data):
- self.transport.write(data)
-
- class _OptionState:
- """
- Represents the state of an option on both sides of a telnet
- connection.
-
- @ivar us: The state of the option on this side of the connection.
-
- @ivar him: The state of the option on the other side of the
- connection.
- """
-
- class _Perspective:
- """
- Represents the state of an option on side of the telnet
- connection. Some options can be enabled on a particular side of
- the connection (RFC 1073 for example: only the client can have
- NAWS enabled). Other options can be enabled on either or both
- sides (such as RFC 1372: each side can have its own flow control
- state).
-
- @ivar state: C{'yes'} or C{'no'} indicating whether or not this
- option is enabled on one side of the connection.
-
- @ivar negotiating: A boolean tracking whether negotiation about
- this option is in progress.
-
- @ivar onResult: When negotiation about this option has been
- initiated by this side of the connection, a L{Deferred}
- which will fire with the result of the negotiation. L{None}
- at other times.
- """
-
- state = "no"
- negotiating = False
- onResult = None
-
- def __str__(self) -> str:
- return self.state + ("*" * self.negotiating)
-
- def __init__(self):
- self.us = self._Perspective()
- self.him = self._Perspective()
-
- def __repr__(self) -> str:
- return f"<_OptionState us={self.us} him={self.him}>"
-
- def getOptionState(self, opt):
- return self.options.setdefault(opt, self._OptionState())
-
- def _do(self, option):
- self._write(IAC + DO + option)
-
- def _dont(self, option):
- self._write(IAC + DONT + option)
-
- def _will(self, option):
- self._write(IAC + WILL + option)
-
- def _wont(self, option):
- self._write(IAC + WONT + option)
-
- def will(self, option):
- """
- Indicate our willingness to enable an option.
- """
- s = self.getOptionState(option)
- if s.us.negotiating or s.him.negotiating:
- return defer.fail(AlreadyNegotiating(option))
- elif s.us.state == "yes":
- return defer.fail(AlreadyEnabled(option))
- else:
- s.us.negotiating = True
- s.us.onResult = d = defer.Deferred()
- self._will(option)
- return d
-
- def wont(self, option):
- """
- Indicate we are not willing to enable an option.
- """
- s = self.getOptionState(option)
- if s.us.negotiating or s.him.negotiating:
- return defer.fail(AlreadyNegotiating(option))
- elif s.us.state == "no":
- return defer.fail(AlreadyDisabled(option))
- else:
- s.us.negotiating = True
- s.us.onResult = d = defer.Deferred()
- self._wont(option)
- return d
-
- def do(self, option):
- s = self.getOptionState(option)
- if s.us.negotiating or s.him.negotiating:
- return defer.fail(AlreadyNegotiating(option))
- elif s.him.state == "yes":
- return defer.fail(AlreadyEnabled(option))
- else:
- s.him.negotiating = True
- s.him.onResult = d = defer.Deferred()
- self._do(option)
- return d
-
- def dont(self, option):
- s = self.getOptionState(option)
- if s.us.negotiating or s.him.negotiating:
- return defer.fail(AlreadyNegotiating(option))
- elif s.him.state == "no":
- return defer.fail(AlreadyDisabled(option))
- else:
- s.him.negotiating = True
- s.him.onResult = d = defer.Deferred()
- self._dont(option)
- return d
-
- def requestNegotiation(self, about, data):
- """
- Send a negotiation message for the option C{about} with C{data} as the
- payload.
-
- @param data: the payload
- @type data: L{bytes}
- @see: L{ITelnetTransport.requestNegotiation}
- """
- data = data.replace(IAC, IAC * 2)
- self._write(IAC + SB + about + data + IAC + SE)
-
- def dataReceived(self, data):
- appDataBuffer = []
-
- for b in iterbytes(data):
- if self.state == "data":
- if b == IAC:
- self.state = "escaped"
- elif b == b"\r":
- self.state = "newline"
- else:
- appDataBuffer.append(b)
- elif self.state == "escaped":
- if b == IAC:
- appDataBuffer.append(b)
- self.state = "data"
- elif b == SB:
- self.state = "subnegotiation"
- self.commands = []
- elif b in (EOR, NOP, DM, BRK, IP, AO, AYT, EC, EL, GA):
- self.state = "data"
- if appDataBuffer:
- self.applicationDataReceived(b"".join(appDataBuffer))
- del appDataBuffer[:]
- self.commandReceived(b, None)
- elif b in (WILL, WONT, DO, DONT):
- self.state = "command"
- self.command = b
- else:
- raise ValueError("Stumped", b)
- elif self.state == "command":
- self.state = "data"
- command = self.command
- del self.command
- if appDataBuffer:
- self.applicationDataReceived(b"".join(appDataBuffer))
- del appDataBuffer[:]
- self.commandReceived(command, b)
- elif self.state == "newline":
- self.state = "data"
- if b == b"\n":
- appDataBuffer.append(b"\n")
- elif b == b"\0":
- appDataBuffer.append(b"\r")
- elif b == IAC:
- # IAC isn't really allowed after \r, according to the
- # RFC, but handling it this way is less surprising than
- # delivering the IAC to the app as application data.
- # The purpose of the restriction is to allow terminals
- # to unambiguously interpret the behavior of the CR
- # after reading only one more byte. CR LF is supposed
- # to mean one thing (cursor to next line, first column),
- # CR NUL another (cursor to first column). Absent the
- # NUL, it still makes sense to interpret this as CR and
- # then apply all the usual interpretation to the IAC.
- appDataBuffer.append(b"\r")
- self.state = "escaped"
- else:
- appDataBuffer.append(b"\r" + b)
- elif self.state == "subnegotiation":
- if b == IAC:
- self.state = "subnegotiation-escaped"
- else:
- self.commands.append(b)
- elif self.state == "subnegotiation-escaped":
- if b == SE:
- self.state = "data"
- commands = self.commands
- del self.commands
- if appDataBuffer:
- self.applicationDataReceived(b"".join(appDataBuffer))
- del appDataBuffer[:]
- self.negotiate(commands)
- else:
- self.state = "subnegotiation"
- self.commands.append(b)
- else:
- raise ValueError("How'd you do this?")
-
- if appDataBuffer:
- self.applicationDataReceived(b"".join(appDataBuffer))
-
- def connectionLost(self, reason):
- for state in self.options.values():
- if state.us.onResult is not None:
- d = state.us.onResult
- state.us.onResult = None
- d.errback(reason)
- if state.him.onResult is not None:
- d = state.him.onResult
- state.him.onResult = None
- d.errback(reason)
-
- def applicationDataReceived(self, data):
- """
- Called with application-level data.
- """
-
- def unhandledCommand(self, command, argument):
- """
- Called for commands for which no handler is installed.
- """
-
- def commandReceived(self, command, argument):
- cmdFunc = self.commandMap.get(command)
- if cmdFunc is None:
- self.unhandledCommand(command, argument)
- else:
- cmdFunc(argument)
-
- def unhandledSubnegotiation(self, command, data):
- """
- Called for subnegotiations for which no handler is installed.
- """
-
- def negotiate(self, data):
- command, data = data[0], data[1:]
- cmdFunc = self.negotiationMap.get(command)
- if cmdFunc is None:
- self.unhandledSubnegotiation(command, data)
- else:
- cmdFunc(data)
-
- def telnet_WILL(self, option):
- s = self.getOptionState(option)
- self.willMap[s.him.state, s.him.negotiating](self, s, option)
-
- def will_no_false(self, state, option):
- # He is unilaterally offering to enable an option.
- if self.enableRemote(option):
- state.him.state = "yes"
- self._do(option)
- else:
- self._dont(option)
-
- def will_no_true(self, state, option):
- # Peer agreed to enable an option in response to our request.
- state.him.state = "yes"
- state.him.negotiating = False
- d = state.him.onResult
- state.him.onResult = None
- d.callback(True)
- assert self.enableRemote(
- option
- ), "enableRemote must return True in this context (for option {!r})".format(
- option
- )
-
- def will_yes_false(self, state, option):
- # He is unilaterally offering to enable an already-enabled option.
- # Ignore this.
- pass
-
- def will_yes_true(self, state, option):
- # This is a bogus state. It is here for completeness. It will
- # never be entered.
- assert (
- False
- ), "will_yes_true can never be entered, but was called with {!r}, {!r}".format(
- state,
- option,
- )
-
- willMap = {
- ("no", False): will_no_false,
- ("no", True): will_no_true,
- ("yes", False): will_yes_false,
- ("yes", True): will_yes_true,
- }
-
- def telnet_WONT(self, option):
- s = self.getOptionState(option)
- self.wontMap[s.him.state, s.him.negotiating](self, s, option)
-
- def wont_no_false(self, state, option):
- # He is unilaterally demanding that an already-disabled option be/remain disabled.
- # Ignore this (although we could record it and refuse subsequent enable attempts
- # from our side - he can always refuse them again though, so we won't)
- pass
-
- def wont_no_true(self, state, option):
- # Peer refused to enable an option in response to our request.
- state.him.negotiating = False
- d = state.him.onResult
- state.him.onResult = None
- d.errback(OptionRefused(option))
-
- def wont_yes_false(self, state, option):
- # Peer is unilaterally demanding that an option be disabled.
- state.him.state = "no"
- self.disableRemote(option)
- self._dont(option)
-
- def wont_yes_true(self, state, option):
- # Peer agreed to disable an option at our request.
- state.him.state = "no"
- state.him.negotiating = False
- d = state.him.onResult
- state.him.onResult = None
- d.callback(True)
- self.disableRemote(option)
-
- wontMap = {
- ("no", False): wont_no_false,
- ("no", True): wont_no_true,
- ("yes", False): wont_yes_false,
- ("yes", True): wont_yes_true,
- }
-
- def telnet_DO(self, option):
- s = self.getOptionState(option)
- self.doMap[s.us.state, s.us.negotiating](self, s, option)
-
- def do_no_false(self, state, option):
- # Peer is unilaterally requesting that we enable an option.
- if self.enableLocal(option):
- state.us.state = "yes"
- self._will(option)
- else:
- self._wont(option)
-
- def do_no_true(self, state, option):
- # Peer agreed to allow us to enable an option at our request.
- state.us.state = "yes"
- state.us.negotiating = False
- d = state.us.onResult
- state.us.onResult = None
- d.callback(True)
- self.enableLocal(option)
-
- def do_yes_false(self, state, option):
- # Peer is unilaterally requesting us to enable an already-enabled option.
- # Ignore this.
- pass
-
- def do_yes_true(self, state, option):
- # This is a bogus state. It is here for completeness. It will never be
- # entered.
- assert (
- False
- ), "do_yes_true can never be entered, but was called with {!r}, {!r}".format(
- state,
- option,
- )
-
- doMap = {
- ("no", False): do_no_false,
- ("no", True): do_no_true,
- ("yes", False): do_yes_false,
- ("yes", True): do_yes_true,
- }
-
- def telnet_DONT(self, option):
- s = self.getOptionState(option)
- self.dontMap[s.us.state, s.us.negotiating](self, s, option)
-
- def dont_no_false(self, state, option):
- # Peer is unilaterally demanding us to disable an already-disabled option.
- # Ignore this.
- pass
-
- def dont_no_true(self, state, option):
- # Offered option was refused. Fail the Deferred returned by the
- # previous will() call.
- state.us.negotiating = False
- d = state.us.onResult
- state.us.onResult = None
- d.errback(OptionRefused(option))
-
- def dont_yes_false(self, state, option):
- # Peer is unilaterally demanding we disable an option.
- state.us.state = "no"
- self.disableLocal(option)
- self._wont(option)
-
- def dont_yes_true(self, state, option):
- # Peer acknowledged our notice that we will disable an option.
- state.us.state = "no"
- state.us.negotiating = False
- d = state.us.onResult
- state.us.onResult = None
- d.callback(True)
- self.disableLocal(option)
-
- dontMap = {
- ("no", False): dont_no_false,
- ("no", True): dont_no_true,
- ("yes", False): dont_yes_false,
- ("yes", True): dont_yes_true,
- }
-
- def enableLocal(self, option):
- """
- Reject all attempts to enable options.
- """
- return False
-
- def enableRemote(self, option):
- """
- Reject all attempts to enable options.
- """
- return False
-
- def disableLocal(self, option):
- """
- Signal a programming error by raising an exception.
-
- L{enableLocal} must return true for the given value of C{option} in
- order for this method to be called. If a subclass of L{Telnet}
- overrides enableLocal to allow certain options to be enabled, it must
- also override disableLocal to disable those options.
-
- @raise NotImplementedError: Always raised.
- """
- raise NotImplementedError(
- f"Don't know how to disable local telnet option {option!r}"
- )
-
- def disableRemote(self, option):
- """
- Signal a programming error by raising an exception.
-
- L{enableRemote} must return true for the given value of C{option} in
- order for this method to be called. If a subclass of L{Telnet}
- overrides enableRemote to allow certain options to be enabled, it must
- also override disableRemote tto disable those options.
-
- @raise NotImplementedError: Always raised.
- """
- raise NotImplementedError(
- f"Don't know how to disable remote telnet option {option!r}"
- )
-
-
- class ProtocolTransportMixin:
- def write(self, data):
- self.transport.write(data.replace(b"\n", b"\r\n"))
-
- def writeSequence(self, seq):
- self.transport.writeSequence(seq)
-
- def loseConnection(self):
- self.transport.loseConnection()
-
- def getHost(self):
- return self.transport.getHost()
-
- def getPeer(self):
- return self.transport.getPeer()
-
-
- class TelnetTransport(Telnet, ProtocolTransportMixin):
- """
- @ivar protocol: An instance of the protocol to which this
- transport is connected, or None before the connection is
- established and after it is lost.
-
- @ivar protocolFactory: A callable which returns protocol instances
- which provide L{ITelnetProtocol}. This will be invoked when a
- connection is established. It is passed *protocolArgs and
- **protocolKwArgs.
-
- @ivar protocolArgs: A tuple of additional arguments to
- pass to protocolFactory.
-
- @ivar protocolKwArgs: A dictionary of additional arguments
- to pass to protocolFactory.
- """
-
- disconnecting = False
-
- protocolFactory = None
- protocol = None
-
- def __init__(self, protocolFactory=None, *a, **kw):
- Telnet.__init__(self)
- if protocolFactory is not None:
- self.protocolFactory = protocolFactory
- self.protocolArgs = a
- self.protocolKwArgs = kw
-
- def connectionMade(self):
- if self.protocolFactory is not None:
- self.protocol = self.protocolFactory(
- *self.protocolArgs, **self.protocolKwArgs
- )
- assert ITelnetProtocol.providedBy(self.protocol)
- try:
- factory = self.factory
- except AttributeError:
- pass
- else:
- self.protocol.factory = factory
- self.protocol.makeConnection(self)
-
- def connectionLost(self, reason):
- Telnet.connectionLost(self, reason)
- if self.protocol is not None:
- try:
- self.protocol.connectionLost(reason)
- finally:
- del self.protocol
-
- def enableLocal(self, option):
- return self.protocol.enableLocal(option)
-
- def enableRemote(self, option):
- return self.protocol.enableRemote(option)
-
- def disableLocal(self, option):
- return self.protocol.disableLocal(option)
-
- def disableRemote(self, option):
- return self.protocol.disableRemote(option)
-
- def unhandledSubnegotiation(self, command, data):
- self.protocol.unhandledSubnegotiation(command, data)
-
- def unhandledCommand(self, command, argument):
- self.protocol.unhandledCommand(command, argument)
-
- def applicationDataReceived(self, data):
- self.protocol.dataReceived(data)
-
- def write(self, data):
- ProtocolTransportMixin.write(self, data.replace(b"\xff", b"\xff\xff"))
-
-
- class TelnetBootstrapProtocol(TelnetProtocol, ProtocolTransportMixin):
- protocol = None
-
- def __init__(self, protocolFactory, *args, **kw):
- self.protocolFactory = protocolFactory
- self.protocolArgs = args
- self.protocolKwArgs = kw
-
- def connectionMade(self):
- self.transport.negotiationMap[NAWS] = self.telnet_NAWS
- self.transport.negotiationMap[LINEMODE] = self.telnet_LINEMODE
-
- for opt in (LINEMODE, NAWS, SGA):
- self.transport.do(opt).addErrback(
- lambda f: self._log.failure("Error do {opt!r}", f, opt=opt)
- )
- for opt in (ECHO,):
- self.transport.will(opt).addErrback(
- lambda f: self._log.failure("Error setting will {opt!r}", f, opt=opt)
- )
-
- self.protocol = self.protocolFactory(*self.protocolArgs, **self.protocolKwArgs)
-
- try:
- factory = self.factory
- except AttributeError:
- pass
- else:
- self.protocol.factory = factory
-
- self.protocol.makeConnection(self)
-
- def connectionLost(self, reason):
- if self.protocol is not None:
- try:
- self.protocol.connectionLost(reason)
- finally:
- del self.protocol
-
- def dataReceived(self, data):
- self.protocol.dataReceived(data)
-
- def enableLocal(self, opt):
- if opt == ECHO:
- return True
- elif opt == SGA:
- return True
- else:
- return False
-
- def enableRemote(self, opt):
- if opt == LINEMODE:
- self.transport.requestNegotiation(LINEMODE, MODE + LINEMODE_TRAPSIG)
- return True
- elif opt == NAWS:
- return True
- elif opt == SGA:
- return True
- else:
- return False
-
- def telnet_NAWS(self, data):
- # NAWS is client -> server *only*. self.protocol will
- # therefore be an ITerminalTransport, the `.protocol'
- # attribute of which will be an ITerminalProtocol. Maybe.
- # You know what, XXX TODO clean this up.
- if len(data) == 4:
- width, height = struct.unpack("!HH", b"".join(data))
- self.protocol.terminalProtocol.terminalSize(width, height)
- else:
- self._log.error("Wrong number of NAWS bytes: {nbytes}", nbytes=len(data))
-
- linemodeSubcommands = {LINEMODE_SLC: "SLC"}
-
- def telnet_LINEMODE(self, data):
- # linemodeSubcommand = data[0]
- # # XXX TODO: This should be enabled to parse linemode subnegotiation.
- # getattr(self, "linemode_" + self.linemodeSubcommands[linemodeSubcommand])(
- # data[1:]
- # )
- pass
-
- def linemode_SLC(self, data):
- chunks = zip(*[iter(data)] * 3)
- for slcFunction, slcValue, slcWhat in chunks:
- # Later, we should parse stuff.
- "SLC", ord(slcFunction), ord(slcValue), ord(slcWhat)
-
-
- from twisted.protocols import basic
-
-
- class StatefulTelnetProtocol(basic.LineReceiver, TelnetProtocol):
- delimiter = b"\n"
-
- state = "Discard"
-
- def connectionLost(self, reason):
- basic.LineReceiver.connectionLost(self, reason)
- TelnetProtocol.connectionLost(self, reason)
-
- def lineReceived(self, line):
- oldState = self.state
- newState = getattr(self, "telnet_" + oldState)(line)
- if newState is not None:
- if self.state == oldState:
- self.state = newState
- else:
- self._log.warn("state changed and new state returned")
-
- def telnet_Discard(self, line):
- pass
-
-
- from twisted.cred import credentials
-
-
- class AuthenticatingTelnetProtocol(StatefulTelnetProtocol):
- """
- A protocol which prompts for credentials and attempts to authenticate them.
-
- Username and password prompts are given (the password is obscured). When the
- information is collected, it is passed to a portal and an avatar implementing
- L{ITelnetProtocol} is requested. If an avatar is returned, it connected to this
- protocol's transport, and this protocol's transport is connected to it.
- Otherwise, the user is re-prompted for credentials.
- """
-
- state = "User"
- protocol = None
-
- def __init__(self, portal):
- self.portal = portal
-
- def connectionMade(self):
- self.transport.write(b"Username: ")
-
- def connectionLost(self, reason):
- StatefulTelnetProtocol.connectionLost(self, reason)
- if self.protocol is not None:
- try:
- self.protocol.connectionLost(reason)
- self.logout()
- finally:
- del self.protocol, self.logout
-
- def telnet_User(self, line):
- self.username = line
- self.transport.will(ECHO)
- self.transport.write(b"Password: ")
- return "Password"
-
- def telnet_Password(self, line):
- username, password = self.username, line
- del self.username
-
- def login(ignored):
- creds = credentials.UsernamePassword(username, password)
- d = self.portal.login(creds, None, ITelnetProtocol)
- d.addCallback(self._cbLogin)
- d.addErrback(self._ebLogin)
-
- self.transport.wont(ECHO).addCallback(login)
- return "Discard"
-
- def _cbLogin(self, ial):
- interface, protocol, logout = ial
- assert interface is ITelnetProtocol
- self.protocol = protocol
- self.logout = logout
- self.state = "Command"
-
- protocol.makeConnection(self.transport)
- self.transport.protocol = protocol
-
- def _ebLogin(self, failure):
- self.transport.write(b"\nAuthentication failed\n")
- self.transport.write(b"Username: ")
- self.state = "User"
-
-
- __all__ = [
- # Exceptions
- "TelnetError",
- "NegotiationError",
- "OptionRefused",
- "AlreadyNegotiating",
- "AlreadyEnabled",
- "AlreadyDisabled",
- # Interfaces
- "ITelnetProtocol",
- "ITelnetTransport",
- # Other stuff, protocols, etc.
- "Telnet",
- "TelnetProtocol",
- "TelnetTransport",
- "TelnetBootstrapProtocol",
- ]
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