1r"""TELNET client class.
2
3Based on RFC 854: TELNET Protocol Specification, by J. Postel and
4J. Reynolds
5
6Example:
7
8>>> from telnetlib import Telnet
9>>> tn = Telnet('www.python.org', 79)   # connect to finger port
10>>> tn.write('guido\r\n')
11>>> print tn.read_all()
12Login       Name               TTY         Idle    When    Where
13guido    Guido van Rossum      pts/2        <Dec  2 11:10> snag.cnri.reston..
14
15>>>
16
17Note that read_all() won't read until eof -- it just reads some data
18-- but it guarantees to read at least one byte unless EOF is hit.
19
20It is possible to pass a Telnet object to select.select() in order to
21wait until more data is available.  Note that in this case,
22read_eager() may return '' even if there was data on the socket,
23because the protocol negotiation may have eaten the data.  This is why
24EOFError is needed in some cases to distinguish between "no data" and
25"connection closed" (since the socket also appears ready for reading
26when it is closed).
27
28To do:
29- option negotiation
30- timeout should be intrinsic to the connection object instead of an
31  option on one of the read calls only
32
33"""
34
35
36# Imported modules
37import errno
38import sys
39import socket
40import select
41
42__all__ = ["Telnet"]
43
44# Tunable parameters
45DEBUGLEVEL = 0
46
47# Telnet protocol defaults
48TELNET_PORT = 23
49
50# Telnet protocol characters (don't change)
51IAC  = chr(255) # "Interpret As Command"
52DONT = chr(254)
53DO   = chr(253)
54WONT = chr(252)
55WILL = chr(251)
56theNULL = chr(0)
57
58SE  = chr(240)  # Subnegotiation End
59NOP = chr(241)  # No Operation
60DM  = chr(242)  # Data Mark
61BRK = chr(243)  # Break
62IP  = chr(244)  # Interrupt process
63AO  = chr(245)  # Abort output
64AYT = chr(246)  # Are You There
65EC  = chr(247)  # Erase Character
66EL  = chr(248)  # Erase Line
67GA  = chr(249)  # Go Ahead
68SB =  chr(250)  # Subnegotiation Begin
69
70
71# Telnet protocol options code (don't change)
72# These ones all come from arpa/telnet.h
73BINARY = chr(0) # 8-bit data path
74ECHO = chr(1) # echo
75RCP = chr(2) # prepare to reconnect
76SGA = chr(3) # suppress go ahead
77NAMS = chr(4) # approximate message size
78STATUS = chr(5) # give status
79TM = chr(6) # timing mark
80RCTE = chr(7) # remote controlled transmission and echo
81NAOL = chr(8) # negotiate about output line width
82NAOP = chr(9) # negotiate about output page size
83NAOCRD = chr(10) # negotiate about CR disposition
84NAOHTS = chr(11) # negotiate about horizontal tabstops
85NAOHTD = chr(12) # negotiate about horizontal tab disposition
86NAOFFD = chr(13) # negotiate about formfeed disposition
87NAOVTS = chr(14) # negotiate about vertical tab stops
88NAOVTD = chr(15) # negotiate about vertical tab disposition
89NAOLFD = chr(16) # negotiate about output LF disposition
90XASCII = chr(17) # extended ascii character set
91LOGOUT = chr(18) # force logout
92BM = chr(19) # byte macro
93DET = chr(20) # data entry terminal
94SUPDUP = chr(21) # supdup protocol
95SUPDUPOUTPUT = chr(22) # supdup output
96SNDLOC = chr(23) # send location
97TTYPE = chr(24) # terminal type
98EOR = chr(25) # end or record
99TUID = chr(26) # TACACS user identification
100OUTMRK = chr(27) # output marking
101TTYLOC = chr(28) # terminal location number
102VT3270REGIME = chr(29) # 3270 regime
103X3PAD = chr(30) # X.3 PAD
104NAWS = chr(31) # window size
105TSPEED = chr(32) # terminal speed
106LFLOW = chr(33) # remote flow control
107LINEMODE = chr(34) # Linemode option
108XDISPLOC = chr(35) # X Display Location
109OLD_ENVIRON = chr(36) # Old - Environment variables
110AUTHENTICATION = chr(37) # Authenticate
111ENCRYPT = chr(38) # Encryption option
112NEW_ENVIRON = chr(39) # New - Environment variables
113# the following ones come from
114# http://www.iana.org/assignments/telnet-options
115# Unfortunately, that document does not assign identifiers
116# to all of them, so we are making them up
117TN3270E = chr(40) # TN3270E
118XAUTH = chr(41) # XAUTH
119CHARSET = chr(42) # CHARSET
120RSP = chr(43) # Telnet Remote Serial Port
121COM_PORT_OPTION = chr(44) # Com Port Control Option
122SUPPRESS_LOCAL_ECHO = chr(45) # Telnet Suppress Local Echo
123TLS = chr(46) # Telnet Start TLS
124KERMIT = chr(47) # KERMIT
125SEND_URL = chr(48) # SEND-URL
126FORWARD_X = chr(49) # FORWARD_X
127PRAGMA_LOGON = chr(138) # TELOPT PRAGMA LOGON
128SSPI_LOGON = chr(139) # TELOPT SSPI LOGON
129PRAGMA_HEARTBEAT = chr(140) # TELOPT PRAGMA HEARTBEAT
130EXOPL = chr(255) # Extended-Options-List
131NOOPT = chr(0)
132
133class Telnet:
134
135    """Telnet interface class.
136
137    An instance of this class represents a connection to a telnet
138    server.  The instance is initially not connected; the open()
139    method must be used to establish a connection.  Alternatively, the
140    host name and optional port number can be passed to the
141    constructor, too.
142
143    Don't try to reopen an already connected instance.
144
145    This class has many read_*() methods.  Note that some of them
146    raise EOFError when the end of the connection is read, because
147    they can return an empty string for other reasons.  See the
148    individual doc strings.
149
150    read_until(expected, [timeout])
151        Read until the expected string has been seen, or a timeout is
152        hit (default is no timeout); may block.
153
154    read_all()
155        Read all data until EOF; may block.
156
157    read_some()
158        Read at least one byte or EOF; may block.
159
160    read_very_eager()
161        Read all data available already queued or on the socket,
162        without blocking.
163
164    read_eager()
165        Read either data already queued or some data available on the
166        socket, without blocking.
167
168    read_lazy()
169        Read all data in the raw queue (processing it first), without
170        doing any socket I/O.
171
172    read_very_lazy()
173        Reads all data in the cooked queue, without doing any socket
174        I/O.
175
176    read_sb_data()
177        Reads available data between SB ... SE sequence. Don't block.
178
179    set_option_negotiation_callback(callback)
180        Each time a telnet option is read on the input flow, this callback
181        (if set) is called with the following parameters :
182        callback(telnet socket, command, option)
183            option will be chr(0) when there is no option.
184        No other action is done afterwards by telnetlib.
185
186    """
187
188    def __init__(self, host=None, port=0,
189                 timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
190        """Constructor.
191
192        When called without arguments, create an unconnected instance.
193        With a hostname argument, it connects the instance; port number
194        and timeout are optional.
195        """
196        self.debuglevel = DEBUGLEVEL
197        self.host = host
198        self.port = port
199        self.timeout = timeout
200        self.sock = None
201        self.rawq = ''
202        self.irawq = 0
203        self.cookedq = ''
204        self.eof = 0
205        self.iacseq = '' # Buffer for IAC sequence.
206        self.sb = 0 # flag for SB and SE sequence.
207        self.sbdataq = ''
208        self.option_callback = None
209        self._has_poll = hasattr(select, 'poll')
210        if host is not None:
211            self.open(host, port, timeout)
212
213    def open(self, host, port=0, timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
214        """Connect to a host.
215
216        The optional second argument is the port number, which
217        defaults to the standard telnet port (23).
218
219        Don't try to reopen an already connected instance.
220        """
221        self.eof = 0
222        if not port:
223            port = TELNET_PORT
224        self.host = host
225        self.port = port
226        self.timeout = timeout
227        self.sock = socket.create_connection((host, port), timeout)
228
229    def __del__(self):
230        """Destructor -- close the connection."""
231        self.close()
232
233    def msg(self, msg, *args):
234        """Print a debug message, when the debug level is > 0.
235
236        If extra arguments are present, they are substituted in the
237        message using the standard string formatting operator.
238
239        """
240        if self.debuglevel > 0:
241            print 'Telnet(%s,%s):' % (self.host, self.port),
242            if args:
243                print msg % args
244            else:
245                print msg
246
247    def set_debuglevel(self, debuglevel):
248        """Set the debug level.
249
250        The higher it is, the more debug output you get (on sys.stdout).
251
252        """
253        self.debuglevel = debuglevel
254
255    def close(self):
256        """Close the connection."""
257        if self.sock:
258            self.sock.close()
259        self.sock = 0
260        self.eof = 1
261        self.iacseq = ''
262        self.sb = 0
263
264    def get_socket(self):
265        """Return the socket object used internally."""
266        return self.sock
267
268    def fileno(self):
269        """Return the fileno() of the socket object used internally."""
270        return self.sock.fileno()
271
272    def write(self, buffer):
273        """Write a string to the socket, doubling any IAC characters.
274
275        Can block if the connection is blocked.  May raise
276        socket.error if the connection is closed.
277
278        """
279        if IAC in buffer:
280            buffer = buffer.replace(IAC, IAC+IAC)
281        self.msg("send %r", buffer)
282        self.sock.sendall(buffer)
283
284    def read_until(self, match, timeout=None):
285        """Read until a given string is encountered or until timeout.
286
287        When no match is found, return whatever is available instead,
288        possibly the empty string.  Raise EOFError if the connection
289        is closed and no cooked data is available.
290
291        """
292        if self._has_poll:
293            return self._read_until_with_poll(match, timeout)
294        else:
295            return self._read_until_with_select(match, timeout)
296
297    def _read_until_with_poll(self, match, timeout):
298        """Read until a given string is encountered or until timeout.
299
300        This method uses select.poll() to implement the timeout.
301        """
302        n = len(match)
303        call_timeout = timeout
304        if timeout is not None:
305            from time import time
306            time_start = time()
307        self.process_rawq()
308        i = self.cookedq.find(match)
309        if i < 0:
310            poller = select.poll()
311            poll_in_or_priority_flags = select.POLLIN | select.POLLPRI
312            poller.register(self, poll_in_or_priority_flags)
313            while i < 0 and not self.eof:
314                try:
315                    ready = poller.poll(call_timeout)
316                except select.error as e:
317                    if e.errno == errno.EINTR:
318                        if timeout is not None:
319                            elapsed = time() - time_start
320                            call_timeout = timeout-elapsed
321                        continue
322                    raise
323                for fd, mode in ready:
324                    if mode & poll_in_or_priority_flags:
325                        i = max(0, len(self.cookedq)-n)
326                        self.fill_rawq()
327                        self.process_rawq()
328                        i = self.cookedq.find(match, i)
329                if timeout is not None:
330                    elapsed = time() - time_start
331                    if elapsed >= timeout:
332                        break
333                    call_timeout = timeout-elapsed
334            poller.unregister(self)
335        if i >= 0:
336            i = i + n
337            buf = self.cookedq[:i]
338            self.cookedq = self.cookedq[i:]
339            return buf
340        return self.read_very_lazy()
341
342    def _read_until_with_select(self, match, timeout=None):
343        """Read until a given string is encountered or until timeout.
344
345        The timeout is implemented using select.select().
346        """
347        n = len(match)
348        self.process_rawq()
349        i = self.cookedq.find(match)
350        if i >= 0:
351            i = i+n
352            buf = self.cookedq[:i]
353            self.cookedq = self.cookedq[i:]
354            return buf
355        s_reply = ([self], [], [])
356        s_args = s_reply
357        if timeout is not None:
358            s_args = s_args + (timeout,)
359            from time import time
360            time_start = time()
361        while not self.eof and select.select(*s_args) == s_reply:
362            i = max(0, len(self.cookedq)-n)
363            self.fill_rawq()
364            self.process_rawq()
365            i = self.cookedq.find(match, i)
366            if i >= 0:
367                i = i+n
368                buf = self.cookedq[:i]
369                self.cookedq = self.cookedq[i:]
370                return buf
371            if timeout is not None:
372                elapsed = time() - time_start
373                if elapsed >= timeout:
374                    break
375                s_args = s_reply + (timeout-elapsed,)
376        return self.read_very_lazy()
377
378    def read_all(self):
379        """Read all data until EOF; block until connection closed."""
380        self.process_rawq()
381        while not self.eof:
382            self.fill_rawq()
383            self.process_rawq()
384        buf = self.cookedq
385        self.cookedq = ''
386        return buf
387
388    def read_some(self):
389        """Read at least one byte of cooked data unless EOF is hit.
390
391        Return '' if EOF is hit.  Block if no data is immediately
392        available.
393
394        """
395        self.process_rawq()
396        while not self.cookedq and not self.eof:
397            self.fill_rawq()
398            self.process_rawq()
399        buf = self.cookedq
400        self.cookedq = ''
401        return buf
402
403    def read_very_eager(self):
404        """Read everything that's possible without blocking in I/O (eager).
405
406        Raise EOFError if connection closed and no cooked data
407        available.  Return '' if no cooked data available otherwise.
408        Don't block unless in the midst of an IAC sequence.
409
410        """
411        self.process_rawq()
412        while not self.eof and self.sock_avail():
413            self.fill_rawq()
414            self.process_rawq()
415        return self.read_very_lazy()
416
417    def read_eager(self):
418        """Read readily available data.
419
420        Raise EOFError if connection closed and no cooked data
421        available.  Return '' if no cooked data available otherwise.
422        Don't block unless in the midst of an IAC sequence.
423
424        """
425        self.process_rawq()
426        while not self.cookedq and not self.eof and self.sock_avail():
427            self.fill_rawq()
428            self.process_rawq()
429        return self.read_very_lazy()
430
431    def read_lazy(self):
432        """Process and return data that's already in the queues (lazy).
433
434        Raise EOFError if connection closed and no data available.
435        Return '' if no cooked data available otherwise.  Don't block
436        unless in the midst of an IAC sequence.
437
438        """
439        self.process_rawq()
440        return self.read_very_lazy()
441
442    def read_very_lazy(self):
443        """Return any data available in the cooked queue (very lazy).
444
445        Raise EOFError if connection closed and no data available.
446        Return '' if no cooked data available otherwise.  Don't block.
447
448        """
449        buf = self.cookedq
450        self.cookedq = ''
451        if not buf and self.eof and not self.rawq:
452            raise EOFError, 'telnet connection closed'
453        return buf
454
455    def read_sb_data(self):
456        """Return any data available in the SB ... SE queue.
457
458        Return '' if no SB ... SE available. Should only be called
459        after seeing a SB or SE command. When a new SB command is
460        found, old unread SB data will be discarded. Don't block.
461
462        """
463        buf = self.sbdataq
464        self.sbdataq = ''
465        return buf
466
467    def set_option_negotiation_callback(self, callback):
468        """Provide a callback function called after each receipt of a telnet option."""
469        self.option_callback = callback
470
471    def process_rawq(self):
472        """Transfer from raw queue to cooked queue.
473
474        Set self.eof when connection is closed.  Don't block unless in
475        the midst of an IAC sequence.
476
477        """
478        buf = ['', '']
479        try:
480            while self.rawq:
481                c = self.rawq_getchar()
482                if not self.iacseq:
483                    if c == theNULL:
484                        continue
485                    if c == "\021":
486                        continue
487                    if c != IAC:
488                        buf[self.sb] = buf[self.sb] + c
489                        continue
490                    else:
491                        self.iacseq += c
492                elif len(self.iacseq) == 1:
493                    # 'IAC: IAC CMD [OPTION only for WILL/WONT/DO/DONT]'
494                    if c in (DO, DONT, WILL, WONT):
495                        self.iacseq += c
496                        continue
497
498                    self.iacseq = ''
499                    if c == IAC:
500                        buf[self.sb] = buf[self.sb] + c
501                    else:
502                        if c == SB: # SB ... SE start.
503                            self.sb = 1
504                            self.sbdataq = ''
505                        elif c == SE:
506                            self.sb = 0
507                            self.sbdataq = self.sbdataq + buf[1]
508                            buf[1] = ''
509                        if self.option_callback:
510                            # Callback is supposed to look into
511                            # the sbdataq
512                            self.option_callback(self.sock, c, NOOPT)
513                        else:
514                            # We can't offer automatic processing of
515                            # suboptions. Alas, we should not get any
516                            # unless we did a WILL/DO before.
517                            self.msg('IAC %d not recognized' % ord(c))
518                elif len(self.iacseq) == 2:
519                    cmd = self.iacseq[1]
520                    self.iacseq = ''
521                    opt = c
522                    if cmd in (DO, DONT):
523                        self.msg('IAC %s %d',
524                            cmd == DO and 'DO' or 'DONT', ord(opt))
525                        if self.option_callback:
526                            self.option_callback(self.sock, cmd, opt)
527                        else:
528                            self.sock.sendall(IAC + WONT + opt)
529                    elif cmd in (WILL, WONT):
530                        self.msg('IAC %s %d',
531                            cmd == WILL and 'WILL' or 'WONT', ord(opt))
532                        if self.option_callback:
533                            self.option_callback(self.sock, cmd, opt)
534                        else:
535                            self.sock.sendall(IAC + DONT + opt)
536        except EOFError: # raised by self.rawq_getchar()
537            self.iacseq = '' # Reset on EOF
538            self.sb = 0
539            pass
540        self.cookedq = self.cookedq + buf[0]
541        self.sbdataq = self.sbdataq + buf[1]
542
543    def rawq_getchar(self):
544        """Get next char from raw queue.
545
546        Block if no data is immediately available.  Raise EOFError
547        when connection is closed.
548
549        """
550        if not self.rawq:
551            self.fill_rawq()
552            if self.eof:
553                raise EOFError
554        c = self.rawq[self.irawq]
555        self.irawq = self.irawq + 1
556        if self.irawq >= len(self.rawq):
557            self.rawq = ''
558            self.irawq = 0
559        return c
560
561    def fill_rawq(self):
562        """Fill raw queue from exactly one recv() system call.
563
564        Block if no data is immediately available.  Set self.eof when
565        connection is closed.
566
567        """
568        if self.irawq >= len(self.rawq):
569            self.rawq = ''
570            self.irawq = 0
571        # The buffer size should be fairly small so as to avoid quadratic
572        # behavior in process_rawq() above
573        buf = self.sock.recv(50)
574        self.msg("recv %r", buf)
575        self.eof = (not buf)
576        self.rawq = self.rawq + buf
577
578    def sock_avail(self):
579        """Test whether data is available on the socket."""
580        return select.select([self], [], [], 0) == ([self], [], [])
581
582    def interact(self):
583        """Interaction function, emulates a very dumb telnet client."""
584        if sys.platform == "win32":
585            self.mt_interact()
586            return
587        while 1:
588            rfd, wfd, xfd = select.select([self, sys.stdin], [], [])
589            if self in rfd:
590                try:
591                    text = self.read_eager()
592                except EOFError:
593                    print '*** Connection closed by remote host ***'
594                    break
595                if text:
596                    sys.stdout.write(text)
597                    sys.stdout.flush()
598            if sys.stdin in rfd:
599                line = sys.stdin.readline()
600                if not line:
601                    break
602                self.write(line)
603
604    def mt_interact(self):
605        """Multithreaded version of interact()."""
606        import thread
607        thread.start_new_thread(self.listener, ())
608        while 1:
609            line = sys.stdin.readline()
610            if not line:
611                break
612            self.write(line)
613
614    def listener(self):
615        """Helper for mt_interact() -- this executes in the other thread."""
616        while 1:
617            try:
618                data = self.read_eager()
619            except EOFError:
620                print '*** Connection closed by remote host ***'
621                return
622            if data:
623                sys.stdout.write(data)
624            else:
625                sys.stdout.flush()
626
627    def expect(self, list, timeout=None):
628        """Read until one from a list of a regular expressions matches.
629
630        The first argument is a list of regular expressions, either
631        compiled (re.RegexObject instances) or uncompiled (strings).
632        The optional second argument is a timeout, in seconds; default
633        is no timeout.
634
635        Return a tuple of three items: the index in the list of the
636        first regular expression that matches; the match object
637        returned; and the text read up till and including the match.
638
639        If EOF is read and no text was read, raise EOFError.
640        Otherwise, when nothing matches, return (-1, None, text) where
641        text is the text received so far (may be the empty string if a
642        timeout happened).
643
644        If a regular expression ends with a greedy match (e.g. '.*')
645        or if more than one expression can match the same input, the
646        results are undeterministic, and may depend on the I/O timing.
647
648        """
649        if self._has_poll:
650            return self._expect_with_poll(list, timeout)
651        else:
652            return self._expect_with_select(list, timeout)
653
654    def _expect_with_poll(self, expect_list, timeout=None):
655        """Read until one from a list of a regular expressions matches.
656
657        This method uses select.poll() to implement the timeout.
658        """
659        re = None
660        expect_list = expect_list[:]
661        indices = range(len(expect_list))
662        for i in indices:
663            if not hasattr(expect_list[i], "search"):
664                if not re: import re
665                expect_list[i] = re.compile(expect_list[i])
666        call_timeout = timeout
667        if timeout is not None:
668            from time import time
669            time_start = time()
670        self.process_rawq()
671        m = None
672        for i in indices:
673            m = expect_list[i].search(self.cookedq)
674            if m:
675                e = m.end()
676                text = self.cookedq[:e]
677                self.cookedq = self.cookedq[e:]
678                break
679        if not m:
680            poller = select.poll()
681            poll_in_or_priority_flags = select.POLLIN | select.POLLPRI
682            poller.register(self, poll_in_or_priority_flags)
683            while not m and not self.eof:
684                try:
685                    ready = poller.poll(call_timeout)
686                except select.error as e:
687                    if e.errno == errno.EINTR:
688                        if timeout is not None:
689                            elapsed = time() - time_start
690                            call_timeout = timeout-elapsed
691                        continue
692                    raise
693                for fd, mode in ready:
694                    if mode & poll_in_or_priority_flags:
695                        self.fill_rawq()
696                        self.process_rawq()
697                        for i in indices:
698                            m = expect_list[i].search(self.cookedq)
699                            if m:
700                                e = m.end()
701                                text = self.cookedq[:e]
702                                self.cookedq = self.cookedq[e:]
703                                break
704                if timeout is not None:
705                    elapsed = time() - time_start
706                    if elapsed >= timeout:
707                        break
708                    call_timeout = timeout-elapsed
709            poller.unregister(self)
710        if m:
711            return (i, m, text)
712        text = self.read_very_lazy()
713        if not text and self.eof:
714            raise EOFError
715        return (-1, None, text)
716
717    def _expect_with_select(self, list, timeout=None):
718        """Read until one from a list of a regular expressions matches.
719
720        The timeout is implemented using select.select().
721        """
722        re = None
723        list = list[:]
724        indices = range(len(list))
725        for i in indices:
726            if not hasattr(list[i], "search"):
727                if not re: import re
728                list[i] = re.compile(list[i])
729        if timeout is not None:
730            from time import time
731            time_start = time()
732        while 1:
733            self.process_rawq()
734            for i in indices:
735                m = list[i].search(self.cookedq)
736                if m:
737                    e = m.end()
738                    text = self.cookedq[:e]
739                    self.cookedq = self.cookedq[e:]
740                    return (i, m, text)
741            if self.eof:
742                break
743            if timeout is not None:
744                elapsed = time() - time_start
745                if elapsed >= timeout:
746                    break
747                s_args = ([self.fileno()], [], [], timeout-elapsed)
748                r, w, x = select.select(*s_args)
749                if not r:
750                    break
751            self.fill_rawq()
752        text = self.read_very_lazy()
753        if not text and self.eof:
754            raise EOFError
755        return (-1, None, text)
756
757
758def test():
759    """Test program for telnetlib.
760
761    Usage: python telnetlib.py [-d] ... [host [port]]
762
763    Default host is localhost; default port is 23.
764
765    """
766    debuglevel = 0
767    while sys.argv[1:] and sys.argv[1] == '-d':
768        debuglevel = debuglevel+1
769        del sys.argv[1]
770    host = 'localhost'
771    if sys.argv[1:]:
772        host = sys.argv[1]
773    port = 0
774    if sys.argv[2:]:
775        portstr = sys.argv[2]
776        try:
777            port = int(portstr)
778        except ValueError:
779            port = socket.getservbyname(portstr, 'tcp')
780    tn = Telnet()
781    tn.set_debuglevel(debuglevel)
782    tn.open(host, port, timeout=0.5)
783    tn.interact()
784    tn.close()
785
786if __name__ == '__main__':
787    test()
788