r"""TELNET client class.

Based on RFC 854: TELNET Protocol Specification, by J. Postel and

J. Reynolds

Example:

>>> from telnetlib import Telnet

>>> tn = Telnet('www.python.org', 79)   # connect to finger port

>>> tn.write('guido\r\n')

>>> print tn.read_all()

Login       Name               TTY         Idle    When    Where

guido    Guido van Rossum      pts/2        <Dec  2 11:10> snag.cnri.reston..

>>>

Note that read_all() won't read until eof -- it just reads some data

-- but it guarantees to read at least one byte unless EOF is hit.

It is possible to pass a Telnet object to select.select() in order to

wait until more data is available.  Note that in this case,

read_eager() may return '' even if there was data on the socket,

because the protocol negotiation may have eaten the data.  This is why

EOFError is needed in some cases to distinguish between "no data" and

"connection closed" (since the socket also appears ready for reading

when it is closed).

To do:

- option negotiation

- timeout should be intrinsic to the connection object instead of an

  option on one of the read calls only

"""

# Imported modules

import sys

import socket

import select

__all__ = ["Telnet"]

# Tunable parameters

DEBUGLEVEL = 0

# Telnet protocol defaults

TELNET_PORT = 23

# Telnet protocol characters (don't change)

IAC  = chr(255) # "Interpret As Command"

DONT = chr(254)

DO   = chr(253)

WONT = chr(252)

WILL = chr(251)

theNULL = chr(0)

SE  = chr(240)  # Subnegotiation End

NOP = chr(241)  # No Operation

DM  = chr(242)  # Data Mark

BRK = chr(243)  # Break

IP  = chr(244)  # Interrupt process

AO  = chr(245)  # Abort output

AYT = chr(246)  # Are You There

EC  = chr(247)  # Erase Character

EL  = chr(248)  # Erase Line

GA  = chr(249)  # Go Ahead

SB =  chr(250)  # Subnegotiation Begin

# Telnet protocol options code (don't change)

# These ones all come from arpa/telnet.h

BINARY = chr(0) # 8-bit data path

ECHO = chr(1) # echo

RCP = chr(2) # prepare to reconnect

SGA = chr(3) # suppress go ahead

NAMS = chr(4) # approximate message size

STATUS = chr(5) # give status

TM = chr(6) # timing mark

RCTE = chr(7) # remote controlled transmission and echo

NAOL = chr(8) # negotiate about output line width

NAOP = chr(9) # negotiate about output page size

NAOCRD = chr(10) # negotiate about CR disposition

NAOHTS = chr(11) # negotiate about horizontal tabstops

NAOHTD = chr(12) # negotiate about horizontal tab disposition

NAOFFD = chr(13) # negotiate about formfeed disposition

NAOVTS = chr(14) # negotiate about vertical tab stops

NAOVTD = chr(15) # negotiate about vertical tab disposition

NAOLFD = chr(16) # negotiate about output LF disposition

XASCII = chr(17) # extended ascii character set

LOGOUT = chr(18) # force logout

BM = chr(19) # byte macro

DET = chr(20) # data entry terminal

SUPDUP = chr(21) # supdup protocol

SUPDUPOUTPUT = chr(22) # supdup output

SNDLOC = chr(23) # send location

TTYPE = chr(24) # terminal type

EOR = chr(25) # end or record

TUID = chr(26) # TACACS user identification

OUTMRK = chr(27) # output marking

TTYLOC = chr(28) # terminal location number

VT3270REGIME = chr(29) # 3270 regime

X3PAD = chr(30) # X.3 PAD

NAWS = chr(31) # window size

TSPEED = chr(32) # terminal speed

LFLOW = chr(33) # remote flow control

LINEMODE = chr(34) # Linemode option

XDISPLOC = chr(35) # X Display Location

OLD_ENVIRON = chr(36) # Old - Environment variables

AUTHENTICATION = chr(37) # Authenticate

ENCRYPT = chr(38) # Encryption option

NEW_ENVIRON = chr(39) # New - Environment variables

# the following ones come from

# http://www.iana.org/assignments/telnet-options

# Unfortunately, that document does not assign identifiers

# to all of them, so we are making them up

TN3270E = chr(40) # TN3270E

XAUTH = chr(41) # XAUTH

CHARSET = chr(42) # CHARSET

RSP = chr(43) # Telnet Remote Serial Port

COM_PORT_OPTION = chr(44) # Com Port Control Option

SUPPRESS_LOCAL_ECHO = chr(45) # Telnet Suppress Local Echo

TLS = chr(46) # Telnet Start TLS

KERMIT = chr(47) # KERMIT

SEND_URL = chr(48) # SEND-URL

FORWARD_X = chr(49) # FORWARD_X

PRAGMA_LOGON = chr(138) # TELOPT PRAGMA LOGON

SSPI_LOGON = chr(139) # TELOPT SSPI LOGON

PRAGMA_HEARTBEAT = chr(140) # TELOPT PRAGMA HEARTBEAT

EXOPL = chr(255) # Extended-Options-List

NOOPT = chr(0)

class Telnet:

    """Telnet interface class.

    An instance of this class represents a connection to a telnet

    server.  The instance is initially not connected; the open()

    method must be used to establish a connection.  Alternatively, the

    host name and optional port number can be passed to the

    constructor, too.

    Don't try to reopen an already connected instance.

    This class has many read_*() methods.  Note that some of them

    raise EOFError when the end of the connection is read, because

    they can return an empty string for other reasons.  See the

    individual doc strings.

    read_until(expected, [timeout])

        Read until the expected string has been seen, or a timeout is

        hit (default is no timeout); may block.

    read_all()

        Read all data until EOF; may block.

    read_some()

        Read at least one byte or EOF; may block.

    read_very_eager()

        Read all data available already queued or on the socket,

        without blocking.

    read_eager()

        Read either data already queued or some data available on the

        socket, without blocking.

    read_lazy()

        Read all data in the raw queue (processing it first), without

        doing any socket I/O.

    read_very_lazy()

        Reads all data in the cooked queue, without doing any socket

        I/O.

    read_sb_data()

        Reads available data between SB ... SE sequence. Don't block.

    set_option_negotiation_callback(callback)

        Each time a telnet option is read on the input flow, this callback

        (if set) is called with the following parameters :

        callback(telnet socket, command, option)

            option will be chr(0) when there is no option.

        No other action is done afterwards by telnetlib.

    """

    def __init__(self, host=None, port=0):

        """Constructor.

        When called without arguments, create an unconnected instance.

        With a hostname argument, it connects the instance; a port

        number is optional.

        """

        self.debuglevel = DEBUGLEVEL

        self.host = host

        self.port = port

        self.sock = None

        self.rawq = ''

        self.irawq = 0

        self.cookedq = ''

        self.eof = 0

        self.iacseq = '' # Buffer for IAC sequence.

        self.sb = 0 # flag for SB and SE sequence.

        self.sbdataq = ''

        self.option_callback = None

        if host is not None:

            self.open(host, port)

    def open(self, host, port=0):

        """Connect to a host.

        The optional second argument is the port number, which

        defaults to the standard telnet port (23).

        Don't try to reopen an already connected instance.

        """

        self.eof = 0

        if not port:

            port = TELNET_PORT

        self.host = host

        self.port = port

        msg = "getaddrinfo returns an empty list"

        for res in socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM):

            af, socktype, proto, canonname, sa = res

            try:

                self.sock = socket.socket(af, socktype, proto)

                self.sock.connect(sa)

            except socket.error, msg:

                if self.sock:

                    self.sock.close()

                self.sock = None

                continue

            break

        if not self.sock:

            raise socket.error, msg

    def __del__(self):

        """Destructor -- close the connection."""

        self.close()

    def msg(self, msg, *args):

        """Print a debug message, when the debug level is > 0.

        If extra arguments are present, they are substituted in the

        message using the standard string formatting operator.

        """

        if self.debuglevel > 0:

            print 'Telnet(%s,%d):' % (self.host, self.port),

            if args:

                print msg % args

            else:

                print msg

    def set_debuglevel(self, debuglevel):

        """Set the debug level.

        The higher it is, the more debug output you get (on sys.stdout).

        """

        self.debuglevel = debuglevel

    def close(self):

        """Close the connection."""

        if self.sock:

            self.sock.close()

        self.sock = 0

        self.eof = 1

        self.iacseq = ''

        self.sb = 0

    def get_socket(self):

        """Return the socket object used internally."""

        return self.sock

    def fileno(self):

        """Return the fileno() of the socket object used internally."""

        return self.sock.fileno()

    def write(self, buffer):

        """Write a string to the socket, doubling any IAC characters.

        Can block if the connection is blocked.  May raise

        socket.error if the connection is closed.

        """

        if IAC in buffer:

            buffer = buffer.replace(IAC, IAC+IAC)

        self.msg("send %r", buffer)

        self.sock.sendall(buffer)

    def read_until(self, match, timeout=None):

        """Read until a given string is encountered or until timeout.

        When no match is found, return whatever is available instead,

        possibly the empty string.  Raise EOFError if the connection

        is closed and no cooked data is available.

        """

        n = len(match)

        self.process_rawq()

        i = self.cookedq.find(match)

        if i >= 0:

            i = i+n

            buf = self.cookedq[:i]

            self.cookedq = self.cookedq[i:]

            return buf

        s_reply = ([self], [], [])

        s_args = s_reply

        if timeout is not None:

            s_args = s_args + (timeout,)

            from time import time

            time_start = time()

        while not self.eof and select.select(*s_args) == s_reply:

            i = max(0, len(self.cookedq)-n)

            self.fill_rawq()

            self.process_rawq()

            i = self.cookedq.find(match, i)

            if i >= 0:

                i = i+n

                buf = self.cookedq[:i]

                self.cookedq = self.cookedq[i:]

                return buf

            if timeout is not None:

                elapsed = time() - time_start

                if elapsed >= timeout:

                    break

                s_args = s_reply + (timeout-elapsed,)

        return self.read_very_lazy()

    def read_all(self):

        """Read all data until EOF; block until connection closed."""

        self.process_rawq()

        while not self.eof:

            self.fill_rawq()

            self.process_rawq()

        buf = self.cookedq

        self.cookedq = ''

        return buf

    def read_some(self):

        """Read at least one byte of cooked data unless EOF is hit.

        Return '' if EOF is hit.  Block if no data is immediately

        available.

        """

        self.process_rawq()

        while not self.cookedq and not self.eof:

            self.fill_rawq()

            self.process_rawq()

        buf = self.cookedq

        self.cookedq = ''

        return buf

    def read_very_eager(self):

        """Read everything that's possible without blocking in I/O (eager).

        Raise EOFError if connection closed and no cooked data

        available.  Return '' if no cooked data available otherwise.

        Don't block unless in the midst of an IAC sequence.

        """

        self.process_rawq()

        while not self.eof and self.sock_avail():

            self.fill_rawq()

            self.process_rawq()

        return self.read_very_lazy()

    def read_eager(self):

        """Read readily available data.

        Raise EOFError if connection closed and no cooked data

        available.  Return '' if no cooked data available otherwise.

        Don't block unless in the midst of an IAC sequence.

        """

        self.process_rawq()

        while not self.cookedq and not self.eof and self.sock_avail():

            self.fill_rawq()

            self.process_rawq()

        return self.read_very_lazy()

    def read_lazy(self):

        """Process and return data that's already in the queues (lazy).

        Raise EOFError if connection closed and no data available.

        Return '' if no cooked data available otherwise.  Don't block

        unless in the midst of an IAC sequence.

        """

        self.process_rawq()

        return self.read_very_lazy()

    def read_very_lazy(self):

        """Return any data available in the cooked queue (very lazy).

        Raise EOFError if connection closed and no data available.

        Return '' if no cooked data available otherwise.  Don't block.

        """

        buf = self.cookedq

        self.cookedq = ''

        if not buf and self.eof and not self.rawq:

            raise EOFError, 'telnet connection closed'

        return buf

    def read_sb_data(self):

        """Return any data available in the SB ... SE queue.

        Return '' if no SB ... SE available. Should only be called

        after seeing a SB or SE command. When a new SB command is

        found, old unread SB data will be discarded. Don't block.

        """

        buf = self.sbdataq

        self.sbdataq = ''

        return buf

    def set_option_negotiation_callback(self, callback):

        """Provide a callback function called after each receipt of a telnet option."""

        self.option_callback = callback

    def process_rawq(self):

        """Transfer from raw queue to cooked queue.

        Set self.eof when connection is closed.  Don't block unless in

        the midst of an IAC sequence.

        """

        buf = ['', '']

        try:

            while self.rawq:

                c = self.rawq_getchar()

                if not self.iacseq:

                    if c == theNULL:

                        continue

                    if c == "\021":

                        continue

                    if c != IAC:

                        buf[self.sb] = buf[self.sb] + c

                        continue

                    else:

                        self.iacseq += c

                elif len(self.iacseq) == 1:

                    # 'IAC: IAC CMD [OPTION only for WILL/WONT/DO/DONT]'

                    if c in (DO, DONT, WILL, WONT):

                        self.iacseq += c

                        continue

                    self.iacseq = ''

                    if c == IAC:

                        buf[self.sb] = buf[self.sb] + c

                    else:

                        if c == SB: # SB ... SE start.

                            self.sb = 1

                            self.sbdataq = ''

                        elif c == SE:

                            self.sb = 0

                            self.sbdataq = self.sbdataq + buf[1]

                            buf[1] = ''

                        if self.option_callback:

                            # Callback is supposed to look into

                            # the sbdataq

                            self.option_callback(self.sock, c, NOOPT)

                        else:

                            # We can't offer automatic processing of

                            # suboptions. Alas, we should not get any

                            # unless we did a WILL/DO before.

                            self.msg('IAC %d not recognized' % ord(c))

                elif len(self.iacseq) == 2:

                    cmd = self.iacseq[1]

                    self.iacseq = ''

                    opt = c

                    if cmd in (DO, DONT):

                        self.msg('IAC %s %d',

                            cmd == DO and 'DO' or 'DONT', ord(opt))

                        if self.option_callback:

                            self.option_callback(self.sock, cmd, opt)

                        else:

                            self.sock.sendall(IAC + WONT + opt)

                    elif cmd in (WILL, WONT):

                        self.msg('IAC %s %d',

                            cmd == WILL and 'WILL' or 'WONT', ord(opt))

                        if self.option_callback:

                            self.option_callback(self.sock, cmd, opt)

                        else:

                            self.sock.sendall(IAC + DONT + opt)

        except EOFError: # raised by self.rawq_getchar()

            self.iacseq = '' # Reset on EOF

            self.sb = 0

            pass

        self.cookedq = self.cookedq + buf[0]

        self.sbdataq = self.sbdataq + buf[1]

    def rawq_getchar(self):

        """Get next char from raw queue.

        Block if no data is immediately available.  Raise EOFError

        when connection is closed.

        """

        if not self.rawq:

            self.fill_rawq()

            if self.eof:

                raise EOFError

        c = self.rawq[self.irawq]

        self.irawq = self.irawq + 1

        if self.irawq >= len(self.rawq):

            self.rawq = ''

            self.irawq = 0

        return c

    def fill_rawq(self):

        """Fill raw queue from exactly one recv() system call.

        Block if no data is immediately available.  Set self.eof when

        connection is closed.

        """

        if self.irawq >= len(self.rawq):

            self.rawq = ''

            self.irawq = 0

        # The buffer size should be fairly small so as to avoid quadratic

        # behavior in process_rawq() above

        buf = self.sock.recv(50)