threatcode · pull · Feb 28, 2026 · Feb 28, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -50,7 +50,8 @@ jobs:
         run: python -Im tox -e ${{ matrix.toxenv }}
 
   tests:
-    name: Python ${{ matrix.python-version }} (${{ matrix.os }})${{ matrix.asyncio-debug && ' [asyncio-debug]' || '' }}
+    name: Python ${{ matrix.python-version }} (${{ matrix.os }})${{ matrix.asyncio-debug && ' [asyncio-debug]' || '' }}${{ matrix.optional && ' [OPTIONAL]' || '' }}
+    continue-on-error: ${{ matrix.optional || false }}
     strategy:
       fail-fast: false
       matrix:
@@ -65,15 +66,22 @@ jobs:
           - "3.13"
 
         include:
-          # Python 3.14 pre-release
+          # Python 3.14 pre-release (Linux + Windows)
           - os: ubuntu-latest
             python-version: "3.14"
+          - os: windows-latest
+            python-version: "3.14"
 
           # Python 3.14 with asyncio debug mode
           - os: ubuntu-latest
             python-version: "3.14"
             asyncio-debug: true
 
+          # Python 3.15 pre-release (optional)
+          - os: ubuntu-latest
+            python-version: "3.15"
+            optional: true
+
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -145,9 +153,8 @@ jobs:
           python -Im coverage report --format=markdown >> $GITHUB_STEP_SUMMARY
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v5
         with:
-          token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: false
           verbose: true
 

diff --git a/README.rst b/README.rst
@@ -38,111 +38,109 @@ The python telnetlib.py_ module removed by Python 3.13 is also re-distributed as
 
 See the `Guidebook`_ for examples and the `API documentation`_.
 
-Asyncio Protocol
-----------------
-
-The core protocol and CLI utilities are written using an `Asyncio Interface`_.
-
-Blocking API
-------------
-
-A Synchronous interface, modeled after telnetlib.py_ (client) and miniboa_ (server), with various
-enhancements in protocol negotiation is also provided.  See `sync API documentation`_ for more.
-
 Command-line Utilities
 ----------------------
 
-Two CLI tools are included: ``telnetlib3-client`` for connecting to servers
-and ``telnetlib3-server`` for hosting a server.
+The CLI utility ``telnetlib3-client`` is provided for connecting to servers and
+``telnetlib3-server`` for hosting a server.
 
-Both tools argument ``--shell=my_module.fn_shell`` describing a python
-module path to a function of signature ``async def shell(reader, writer)``.
-The server also provides ``--pty-exec`` argument to host a stand-alone
-program.
+Both tools accept the argument ``--shell=my_module.fn_shell`` describing a python module path to a
+function of signature ``async def shell(reader, writer)``.  The server also provides ``--pty-exec``
+argument to host stand-alone programs.
 
 ::
 
-    # utf8 roguelike server
+    # telnet to utf8 roguelike server
     telnetlib3-client nethack.alt.org
-    # utf8 bbs
+
+    # or bbs,
     telnetlib3-client xibalba.l33t.codes 44510
-    # automatic communication with telnet server
+
+    # automatic script communicates with a server
     telnetlib3-client --shell bin.client_wargame.shell 1984.ws 666
-    # run a server with default shell
+
+    # run a server bound with the default shell bound to 127.0.0.1 6023
     telnetlib3-server
-    # or custom port and ip and shell
+
+    # or custom ip, port and shell
     telnetlib3-server 0.0.0.0 1984 --shell=bin.server_wargame.shell
-    # run an external program with a pseudo-terminal (raw mode is default)
-    telnetlib3-server --pty-exec /bin/bash -- --login
-    # or a linemode program, bc (calculator)
-    telnetlib3-server --pty-exec /bin/bc --line-mode
 
+    # host an external program with a pseudo-terminal (raw mode is default)
+    telnetlib3-server --pty-exec /bin/bash -- --login
 
-There are also fingerprinting CLIs, ``telnetlib3-fingerprint`` and
-``telnetlib3-fingerprint-server``
+    # or host a program in linemode,
+    telnetlib3-server --pty-exec /bin/bc --line-mode
 
-::
+There are also two fingerprinting CLIs, ``telnetlib3-fingerprint`` and
+``telnetlib3-fingerprint-server``::
 
     # host a server, wait for clients to connect and fingerprint them,
     telnetlib3-fingerprint-server
 
-    # report fingerprint of telnet server on 1984.ws
+    # report fingerprint of the telnet server on 1984.ws
     telnetlib3-fingerprint 1984.ws
 
+Encoding
+~~~~~~~~
 
-Legacy telnetlib
-----------------
+The default encoding is the system locale, usually UTF-8, and, without negotiation of BINARY
+transmission, all Telnet protocol text *should* be limited to ASCII text, by strict compliance of
+Telnet.  Further, the encoding used *should* be negotiated by CHARSET.
 
-This library contains an *unadulterated copy* of Python 3.12's telnetlib.py_,
-from the standard library before it was removed in Python 3.13.
+When these conditions are true, telnetlib3-server and telnetlib3-client allow connections of any
+encoding supporting by the python language, and additionally specially ``ATASCII`` and ``PETSCII``
+encodings.  Any server capable of negotiating CHARSET or LANG through NEW_ENVIRON is also presumed
+to support BINARY.
 
-To migrate code, change import statements:
+From a February 2026 `census of MUDs <https://muds.modem.xyz>`_ and `BBSs servers
+<https://bbs.modem.xyz>`_:
 
-.. code-block:: python
+- 2.8% of MUDs support bi-directional CHARSET
+- 0.5% of BBSs support bi-directional CHARSET.
+- 18.4% of BBSs support BINARY.
+- 3.2% of MUDs support BINARY.
 
-    # OLD imports:
-    import telnetlib
+For this reason, it is often required to specify the encoding, eg.!
 
-    # NEW imports:
-    import telnetlib3
+    telnetlib3-client --encoding=cp437 20forbeers.com 1337
 
-``telnetlib3`` did not provide server support, while this library also provides
-both client and server support through a similar Blocking API interface.
+Raw Mode
+~~~~~~~~
 
-See `sync API documentation`_ for details.
+Some telnet servers, especially BBS systems or those designed for serial transmission but are
+connected to a TCP socket without any telnet negotiation may require "raw" mode argument::
 
-Encoding
---------
+    telnetlib3-client --raw-mode area52.tk 5200 --encoding=atascii
 
-Often required, ``--encoding`` and ``--force-binary``::
+Asyncio Protocol
+----------------
 
-    telnetlib3-client --encoding=cp437 --force-binary 20forbeers.com 1337
+The core protocol and CLI utilities are written using an `Asyncio Interface`_.
 
-The default encoding is the system locale, usually UTF-8, but all Telnet
-protocol text *should* be limited to ASCII until BINARY mode is agreed by
-compliance of their respective RFCs.
+Blocking API
+------------
 
-However, many clients and servers that are capable of non-ascii encodings like
-UTF-8 or CP437 may not be capable of negotiating about BINARY, NEW_ENVIRON,
-or CHARSET to negotiate about it.
+A Synchronous interface, modeled after telnetlib.py_ (client) and miniboa_ (server), with various
+enhancements in protocol negotiation is also provided.  See `sync API documentation`_ for more.
 
-In this case, use ``--force-binary`` and ``--encoding`` when the encoding of
-the remote end is known.
+Legacy telnetlib
+----------------
 
-Go-Ahead (GA)
---------------
+This library contains an *unadulterated copy* of Python 3.12's telnetlib.py_,
+from the standard library before it was removed in Python 3.13.
 
-When a client does not negotiate Suppress Go-Ahead (SGA), the server sends
-``IAC GA`` after output to signal that the client may transmit. This is
-correct behavior for MUD clients like Mudlet that expect prompt detection
-via GA.
+To migrate code, change import statements:
 
-If GA causes unwanted output for your use case, disable it::
+.. code-block:: python
 
-    telnetlib3-server --never-send-ga
+    # OLD imports:
+    import telnetlib
 
-For PTY shells, GA is sent after 500ms of output idle time to avoid
-injecting GA in the middle of streaming output.
+    # NEW imports:
+    import telnetlib3
+
+This library *also* provides an additional client (and server) API through a similar interface but
+offering more advanced negotiation features and options.  See `sync API documentation`_ for more.
 
 Quick Example
 =============
@@ -156,7 +154,7 @@ A simple telnet server:
 
     async def shell(reader, writer):
         writer.write('\r\nWould you like to play a game? ')
-        inp = await reader.read(1)
+        inp = await reader.readline()
         if inp:
             writer.echo(inp)
             writer.write('\r\nThey say the only way to win '
@@ -170,6 +168,29 @@ A simple telnet server:
 
     asyncio.run(main())
 
+A client that connects and plays the game:
+
+.. code-block:: python
+
+    import asyncio
+    import telnetlib3
+
+    async def shell(reader, writer):
+        while True:
+            output = await reader.read(1024)
+            if not output:
+                break
+            if '?' in output:
+                writer.write('y\r\n')
+            print(output, end='', flush=True)
+        print()
+
+    async def main():
+        reader, writer = await telnetlib3.open_connection('localhost', 6023)
+        await shell(reader, writer)
+
+    asyncio.run(main())
+
 More examples are available in the `Guidebook`_ and the `bin/`_ directory of the repository.
 
 Features
@@ -185,7 +206,7 @@ The following RFC specifications are implemented:
 * `rfc-857`_, "Telnet Echo Option", May 1983.
 * `rfc-858`_, "Telnet Suppress Go Ahead Option", May 1983.
 * `rfc-859`_, "Telnet Status Option", May 1983.
-* `rfc-860`_, "Telnet Timing mark Option", May 1983.
+* `rfc-860`_, "Telnet Timing Mark Option", May 1983.
 * `rfc-885`_, "Telnet End of Record Option", Dec 1983.
 * `rfc-930`_, "Telnet Terminal Type Option", Jan 1984.
 * `rfc-1073`_, "Telnet Window Size Option", Oct 1988.
@@ -231,18 +252,6 @@ The following RFC specifications are implemented:
 .. _sync API documentation: https://telnetlib3.readthedocs.io/en/latest/api/sync.html
 .. _miniboa: https://github.com/shmup/miniboa
 .. _asyncio: https://docs.python.org/3/library/asyncio.html
-.. _wait_for(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.TelnetConnection.wait_for
-.. _get_extra_info(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.TelnetConnection.get_extra_info
-.. _readline(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.TelnetConnection.readline
-.. _read_until(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.TelnetConnection.read_until
-.. _active: https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.active
-.. _address: https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.address
-.. _terminal_type: https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.terminal_type
-.. _columns: https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.columns
-.. _rows: https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.rows
-.. _idle(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.idle
-.. _duration(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.duration
-.. _deactivate(): https://telnetlib3.readthedocs.io/en/latest/api/sync.html#telnetlib3.sync.ServerConnection.deactivate
 
 Further Reading
 ---------------

diff --git a/bin/__init__.py b/bin/__init__.py
@@ -1 +1 @@
-# bin/ package — shell callbacks for telnetlib3 examples.
+# bin/ package -- shell callbacks for telnetlib3 examples.
diff --git a/bin/server_mud.py b/bin/server_mud.py
@@ -3,8 +3,12 @@
 
 Usage::
 
-    $ python bin/server_mud.py
-    $ telnet localhost 6023
+    $ telnetlib3-server --line-mode --shell bin.server_mud.shell
+    $ telnetlib3-client localhost 6023
+
+The default Telnet server negotiates WILL SGA + WILL ECHO, which puts telnetlib3-client into kludge
+(raw) mode.  MUD clients would prefer that you start the server with ``--line-mode``, to keep
+clients in their (default) NVT line mode.
 """
 
 from __future__ import annotations
@@ -15,12 +19,10 @@
 import random
 import asyncio
 import logging
-import argparse
 import unicodedata
 from typing import Any
 
 # local
-import telnetlib3
 from telnetlib3.telopt import GMCP, MSDP, MSSP, WILL
 from telnetlib3.server_shell import readline2
 
@@ -101,7 +103,7 @@
 }
 
 
-class Weapon:  # pylint: disable=too-few-public-methods
+class Weapon:
     """A weapon that can be held or placed in a room."""
 
     def __init__(self, name: str, damage: tuple[int, int], start_room: str) -> None:
@@ -117,7 +119,7 @@ def damage_display(self) -> str:
         return f"{self.damage[0]}-{self.damage[1]}"
 
 
-class Player:  # pylint: disable=too-few-public-methods
+class Player:
     """A connected player."""
 
     def __init__(self, name: str = "Adventurer") -> None:
@@ -272,9 +274,7 @@ def on_gmcp(writer: Any, package: str, data: Any) -> None:
     writer.write(f"[DEBUG GMCP] {package}: {json.dumps(data)}\r\n")
 
 
-def get_msdp_var(  # pylint: disable=too-many-return-statements
-    player: Player, var: str
-) -> dict[str, Any] | None:
+def get_msdp_var(player: Player, var: str) -> dict[str, Any] | None:
     """Return MSDP value dict for *var*, or ``None`` if unknown."""
     if var == "CHARACTER_NAME":
         return {"CHARACTER_NAME": player.name}
@@ -834,35 +834,3 @@ async def shell(reader: Any, writer: Any) -> None:
         broadcast_room(None, player.room, f"{player.name} has left.")
         update_room_all(player.room)
         writer.close()
-
-
-def parse_args(argv: list[str] | None = None) -> argparse.Namespace:
-    """Parse command-line arguments."""
-    ap = argparse.ArgumentParser(description="Mini-MUD demo server with telnetlib3")
-    ap.add_argument("--host", default="127.0.0.1", help="bind address (default: 127.0.0.1)")
-    ap.add_argument("--port", type=int, default=6023, help="bind port (default: 6023)")
-    ap.add_argument("--log-level", default="INFO", help="log level (default: INFO)")
-    return ap.parse_args(argv)
-
-
-async def main(argv: list[str] | None = None) -> None:
-    """Start the MUD server."""
-    args = parse_args(argv)
-    logging.basicConfig(
-        level=getattr(logging, args.log_level.upper()),
-        format="%(asctime)s %(message)s",
-        datefmt="%H:%M:%S",
-    )
-    server = await telnetlib3.create_server(host=args.host, port=args.port, shell=shell)
-    log.info("%s running on %s:%d", SERVER_NAME, args.host, args.port)
-    print(
-        f"{SERVER_NAME} running on"
-        f" {args.host}:{args.port}\n"
-        f"Connect with: telnet {args.host} {args.port}\n"
-        "Press Ctrl+C to stop"
-    )
-    await server.wait_closed()
-
-
-if __name__ == "__main__":
-    asyncio.run(main())
diff --git a/docs/api/session_context.rst b/docs/api/session_context.rst
@@ -0,0 +1,5 @@
+session_context
+---------------
+
+.. automodule:: telnetlib3._session_context
+   :members:
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		# bin/ package — shell callbacks for telnetlib3 examples.
		# bin/ package -- shell callbacks for telnetlib3 examples.