server_base

Module provides class BaseServer.

class BaseServer(shell=None, _waiter_connected=None, _waiter_closed=None, encoding='utf8', encoding_errors='strict', force_binary=False, connect_maxwait=4.0, limit=None, reader_factory=<class 'telnetlib3.stream_reader.TelnetReader'>, reader_factory_encoding=<class 'telnetlib3.stream_reader.TelnetReaderUnicode'>, writer_factory=<class 'telnetlib3.stream_writer.TelnetWriter'>, writer_factory_encoding=<class 'telnetlib3.stream_writer.TelnetWriterUnicode'>)

Bases: asyncio.streams.FlowControlMixin, asyncio.protocols.Protocol

Base Telnet Server Protocol.

Class initializer.

connect_maxwait = None

maximum duration for check_negotiation().

timeout_connection()

eof_received()

Called when the other end calls write_eof() or equivalent.

This callback may be exercised by the nc(1) client argument -z.

connection_lost(exc)

Called when the connection is lost or closed.

Parameters:exc (Exception) – exception. None indicates close by EOF.

connection_made(transport)

Called when a connection is made.

Sets attributes _transport, _when_connected, _last_received, reader and writer.

Ensure super().connection_made(transport) is called when derived.

begin_shell(result)

data_received(data)

Process bytes received by transport.

duration

Time elapsed since client connected, in seconds as float.

idle

Time elapsed since data last received, in seconds as float.

get_extra_info(name, default=None)

Get optional server protocol or transport information.

begin_negotiation()

Begin on-connect negotiation.

A Telnet server is expected to demand preferred session options immediately after connection. Deriving implementations should always call super().begin_negotiation().

begin_advanced_negotiation()

Begin advanced negotiation.

Callback method further requests advanced telnet options. Called once on receipt of any DO or WILL acknowledgments received, indicating that the remote end is capable of negotiating further.

Only called if sub-classing begin_negotiation() causes at least one negotiation option to be affirmatively acknowledged.

encoding(outgoing=False, incoming=False)

Encoding that should be used for the direction indicated.

The base implementation always returns the encoding given to class initializer, or, when unset (None), US-ASCII.

negotiation_should_advance()

Whether advanced negotiation should commence.

Return type:bool Returns:True if advanced negotiation should be permitted.

The base implementation returns True if any negotiation options were affirmatively acknowledged by client, more than likely options requested in callback begin_negotiation().

check_negotiation(final=False)

Callback, return whether negotiation is complete.

Parameters:final (bool) – Whether this is the final time this callback will be requested to answer regarding protocol negotiation. Returns:Whether negotiation is over (server end is satisfied). Return type:bool

Method is called on each new command byte processed until negotiation is considered final, or after connect_maxwait has elapsed, setting attribute _waiter_connected to value self when complete.

Ensure super().check_negotiation() is called and conditionally combined when derived.

pause_writing()

Called when the transport’s buffer goes over the high-water mark.

Pause and resume calls are paired – pause_writing() is called once when the buffer goes strictly over the high-water mark (even if subsequent writes increases the buffer size even more), and eventually resume_writing() is called once when the buffer size reaches the low-water mark.

Note that if the buffer size equals the high-water mark, pause_writing() is not called – it must go strictly over. Conversely, resume_writing() is called when the buffer size is equal or lower than the low-water mark. These end conditions are important to ensure that things go as expected when either mark is zero.

NOTE: This is the only Protocol callback that is not called through EventLoop.call_soon() – if it were, it would have no effect when it’s most needed (when the app keeps writing without yielding until pause_writing() is called).

resume_writing()

Called when the transport’s buffer drains below the low-water mark.

See pause_writing() for details.