herosdevices.core.bus.telnet.telnetlib
======================================

.. py:module:: herosdevices.core.bus.telnet.telnetlib

.. autoapi-nested-parse::

   TELNET client class.

   Based on the python stdlib telnet library which was deprecated in version 3.12.

   Copyright © 2001-2023 Python Software Foundation; All Rights Reserved

   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





Module Contents
---------------

.. py:class:: Telnet(host=None, port=0, timeout=socket._GLOBAL_DEFAULT_TIMEOUT)

   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.



   .. py:attribute:: sock
      :value: None



   .. py:attribute:: debuglevel
      :value: 0



   .. py:attribute:: host
      :value: None



   .. py:attribute:: port
      :value: 0



   .. py:attribute:: timeout


   .. py:attribute:: rawq
      :value: b''



   .. py:attribute:: irawq
      :value: 0



   .. py:attribute:: cookedq
      :value: b''



   .. py:attribute:: eof
      :value: 0



   .. py:attribute:: iacseq
      :value: b''



   .. py:attribute:: sb
      :value: 0



   .. py:attribute:: sbdataq
      :value: b''



   .. py:attribute:: option_callback
      :value: None



   .. py:method:: open(host, port=0, timeout=socket._GLOBAL_DEFAULT_TIMEOUT)

      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.



   .. py:method:: msg(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.




   .. py:method:: set_debuglevel(debuglevel)

      Set the debug level.

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




   .. py:method:: close()

      Close the connection.



   .. py:method:: get_socket()

      Return the socket object used internally.



   .. py:method:: fileno()

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



   .. py:method:: write(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.




   .. py:method:: read_until(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.




   .. py:method:: read_all()

      Read all data until EOF; block until connection closed.



   .. py:method:: read_some()

      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.




   .. py:method:: read_very_eager()

      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.




   .. py:method:: read_eager()

      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.




   .. py:method:: read_lazy()

      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.




   .. py:method:: read_very_lazy()

      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.




   .. py:method:: read_sb_data()

      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.




   .. py:method:: set_option_negotiation_callback(callback)

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



   .. py:method:: process_rawq()

      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.




   .. py:method:: rawq_getchar()

      Get next char from raw queue.

      Block if no data is immediately available.  Raise EOFError
      when connection is closed.




   .. py:method:: fill_rawq()

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

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




   .. py:method:: sock_avail()

      Test whether data is available on the socket.



   .. py:method:: interact()

      Interaction function, emulates a very dumb telnet client.



   .. py:method:: mt_interact()

      Multithreaded version of interact().



   .. py:method:: listener()

      Helper for mt_interact() -- this executes in the other thread.



   .. py:method:: expect(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.




