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telnetlib
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(b'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 a selector in order to wait until
more data is available. Note that in this case, read_eager() may return b''
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
Classes
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.
close(self)
Close the connection.
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.Pattern 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 re.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.
fileno(self)
Return the fileno() of the socket object used internally.
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.
get_socket(self)
Return the socket object used internally.
interact(self)
Interaction function, emulates a very dumb telnet client.
listener(self)
Helper for mt_interact() -- this executes in the other thread.
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.
mt_interact(self)
Multithreaded version of interact().
open(self, host, port=0, timeout=<object object at 0x7f75e3c944e0>)
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.
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.
rawq_getchar(self)
Get next char from raw queue.
Block if no data is immediately available. Raise EOFError
when connection is closed.
read_all(self)
Read all data until EOF; block until connection closed.
read_eager(self)
Read readily available data.
Raise EOFError if connection closed and no cooked data
available. Return b'' if no cooked data available otherwise.
Don't block unless in the midst of an IAC sequence.
read_lazy(self)
Process and return data that's already in the queues (lazy).
Raise EOFError if connection closed and no data available.
Return b'' if no cooked data available otherwise. Don't block
unless in the midst of an IAC sequence.
read_sb_data(self)
Return any data available in the SB ... SE queue.
Return b'' 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.
read_some(self)
Read at least one byte of cooked data unless EOF is hit.
Return b'' if EOF is hit. Block if no data is immediately
available.
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.
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 b'' if no cooked data available otherwise.
Don't block unless in the midst of an IAC sequence.
read_very_lazy(self)
Return any data available in the cooked queue (very lazy).
Raise EOFError if connection closed and no data available.
Return b'' if no cooked data available otherwise. Don't block.
set_debuglevel(self, debuglevel)
Set the debug level.
The higher it is, the more debug output you get (on sys.stdout).
set_option_negotiation_callback(self, callback)
Provide a callback function called after each receipt of a telnet option.
sock_avail(self)
Test whether data is available on the socket.
write(self, buffer)
Write a string to the socket, doubling any IAC characters.
Can block if the connection is blocked. May raise
OSError if the connection is closed.
Functions
test
test()
Test program for telnetlib.
Usage: python telnetlib.py [-d] ... [host [port]]
Default host is localhost; default port is 23.
Other members
AO = b'\xf5'
AUTHENTICATION = b'%'
AYT = b'\xf6'
BINARY = b'\x00'
BM = b'\x13'
BRK = b'\xf3'
CHARSET = b'*'
COM_PORT_OPTION = b','
DEBUGLEVEL = 0
DET = b'\x14'
DM = b'\xf2'
DO = b'\xfd'
DONT = b'\xfe'
EC = b'\xf7'
ECHO = b'\x01'
EL = b'\xf8'
ENCRYPT = b'&'
EOR = b'\x19'
EXOPL = b'\xff'
FORWARD_X = b'1'
GA = b'\xf9'
IAC = b'\xff'
IP = b'\xf4'
KERMIT = b'/'
LFLOW = b'!'
LINEMODE = b'"'
LOGOUT = b'\x12'
NAMS = b'\x04'
NAOCRD = b'\n'
NAOFFD = b'\r'
NAOHTD = b'\x0c'
NAOHTS = b'\x0b'
NAOL = b'\x08'
NAOLFD = b'\x10'
NAOP = b'\t'
NAOVTD = b'\x0f'
NAOVTS = b'\x0e'
NAWS = b'\x1f'
NEW_ENVIRON = b"'"
NOOPT = b'\x00'
NOP = b'\xf1'
OLD_ENVIRON = b'