| """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). |
| |
| Bugs: |
| - may hang when connection is slow in the middle of an IAC sequence |
| |
| 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) |
| |
| |
| 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. |
| |
| """ |
| |
| 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 |
| if host: |
| 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 |
| self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| self.sock.connect((self.host, self.port)) |
| |
| 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 |
| |
| 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 %s", `buffer`) |
| self.sock.send(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,) |
| while not self.eof and apply(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 |
| 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 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 c == theNULL: |
| continue |
| if c == "\021": |
| continue |
| if c != IAC: |
| buf = buf + c |
| continue |
| c = self.rawq_getchar() |
| if c == IAC: |
| buf = buf + c |
| elif c in (DO, DONT): |
| opt = self.rawq_getchar() |
| self.msg('IAC %s %d', c == DO and 'DO' or 'DONT', ord(c)) |
| self.sock.send(IAC + WONT + opt) |
| elif c in (WILL, WONT): |
| opt = self.rawq_getchar() |
| self.msg('IAC %s %d', |
| c == WILL and 'WILL' or 'WONT', ord(c)) |
| self.sock.send(IAC + DONT + opt) |
| else: |
| self.msg('IAC %s not recognized' % `c`) |
| except EOFError: # raised by self.rawq_getchar() |
| pass |
| self.cookedq = self.cookedq + buf |
| |
| 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) |
| self.msg("recv %s", `buf`) |
| self.eof = (not buf) |
| self.rawq = self.rawq + buf |
| |
| def sock_avail(self): |
| """Test whether data is available on the socket.""" |
| return select.select([self], [], [], 0) == ([self], [], []) |
| |
| def interact(self): |
| """Interaction function, emulates a very dumb telnet client.""" |
| if sys.platform == "win32": |
| self.mt_interact() |
| return |
| while 1: |
| rfd, wfd, xfd = select.select([self, sys.stdin], [], []) |
| if self in rfd: |
| try: |
| text = self.read_eager() |
| except EOFError: |
| print '*** Connection closed by remote host ***' |
| break |
| if text: |
| sys.stdout.write(text) |
| sys.stdout.flush() |
| if sys.stdin in rfd: |
| line = sys.stdin.readline() |
| if not line: |
| break |
| self.write(line) |
| |
| def mt_interact(self): |
| """Multithreaded version of interact().""" |
| import thread |
| thread.start_new_thread(self.listener, ()) |
| while 1: |
| line = sys.stdin.readline() |
| if not line: |
| break |
| self.write(line) |
| |
| def listener(self): |
| """Helper for mt_interact() -- this executes in the other thread.""" |
| while 1: |
| try: |
| data = self.read_eager() |
| except EOFError: |
| print '*** Connection closed by remote host ***' |
| return |
| if data: |
| sys.stdout.write(data) |
| else: |
| sys.stdout.flush() |
| |
| def expect(self, list, timeout=None): |
| """Read until one from a list of a regular expressions matches. |
| |
| The first argument is a list of regular expressions, either |
| compiled (re.RegexObject instances) or uncompiled (strings). |
| The optional second argument is a timeout, in seconds; default |
| is no timeout. |
| |
| Return a tuple of three items: the index in the list of the |
| first regular expression that matches; the match object |
| returned; and the text read up till and including the match. |
| |
| If EOF is read and no text was read, raise EOFError. |
| Otherwise, when nothing matches, return (-1, None, text) where |
| text is the text received so far (may be the empty string if a |
| timeout happened). |
| |
| If a regular expression ends with a greedy match (e.g. '.*') |
| or if more than one expression can match the same input, the |
| results are undeterministic, and may depend on the I/O timing. |
| |
| """ |
| re = None |
| list = list[:] |
| indices = range(len(list)) |
| for i in indices: |
| if not hasattr(list[i], "search"): |
| if not re: import re |
| list[i] = re.compile(list[i]) |
| while 1: |
| self.process_rawq() |
| for i in indices: |
| m = list[i].search(self.cookedq) |
| if m: |
| e = m.end() |
| text = self.cookedq[:e] |
| self.cookedq = self.cookedq[e:] |
| return (i, m, text) |
| if self.eof: |
| break |
| if timeout is not None: |
| r, w, x = select.select([self.fileno()], [], [], timeout) |
| if not r: |
| break |
| self.fill_rawq() |
| text = self.read_very_lazy() |
| if not text and self.eof: |
| raise EOFError |
| return (-1, None, text) |
| |
| |
| def test(): |
| """Test program for telnetlib. |
| |
| Usage: python telnetlib.py [-d] ... [host [port]] |
| |
| Default host is localhost; default port is 23. |
| |
| """ |
| debuglevel = 0 |
| while sys.argv[1:] and sys.argv[1] == '-d': |
| debuglevel = debuglevel+1 |
| del sys.argv[1] |
| host = 'localhost' |
| if sys.argv[1:]: |
| host = sys.argv[1] |
| port = 0 |
| if sys.argv[2:]: |
| portstr = sys.argv[2] |
| try: |
| port = int(portstr) |
| except ValueError: |
| port = socket.getservbyname(portstr, 'tcp') |
| tn = Telnet() |
| tn.set_debuglevel(debuglevel) |
| tn.open(host, port) |
| tn.interact() |
| tn.close() |
| |
| if __name__ == '__main__': |
| test() |