diff options
Diffstat (limited to 'Lib')
| -rw-r--r-- | Lib/telnetlib.py | 424 |
1 files changed, 424 insertions, 0 deletions
diff --git a/Lib/telnetlib.py b/Lib/telnetlib.py new file mode 100644 index 0000000..4595426 --- /dev/null +++ b/Lib/telnetlib.py @@ -0,0 +1,424 @@ +"""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 + +""" + + +# Imported modules +import socket +import select +import string +import regsub + +# 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 = regsub.gsub(IAC, IAC+IAC, 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 = string.find(self.cookedq, 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 = string.find(self.cookedq, 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)) + 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.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.""" + import sys, select + while 1: + rfd, wfd, xfd = select.select([self, sys.stdin], [], []) + if sys.stdin in rfd: + line = sys.stdin.readline() + self.write(line) + 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() + self.close() + + + +def test(): + """Test program for telnetlib. + + Usage: python telnetlib.py [-d] ... [host [port]] + + Default host is localhost; default port is 23. + + """ + import sys + 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() |