"broadcast",

"serve",

"unix_serve",

"ServerConnection",

"Server",

"basic_auth",

"""

:mod:`asyncio` implementation of a WebSocket server connection.

:class:`ServerConnection` provides :meth:`recv` and :meth:`send` methods for

receiving and sending messages.

It supports asynchronous iteration to receive messages::

async for message in websocket:

await process(message)

The iterator exits normally when the connection is closed with close code

1000 (OK) or 1001 (going away) or without a close code. It raises a

:exc:`~websockets.exceptions.ConnectionClosedError` when the connection is

closed with any other code.

The ``ping_interval``, ``ping_timeout``, ``close_timeout``, ``max_queue``,

and ``write_limit`` arguments have the same meaning as in :func:`serve`.

Args:

protocol: Sans-I/O connection.

server: Server that manages this connection.

"""

def __init__(

self,

protocol: ServerProtocol,

server: Server,

*,

ping_interval: float | None = 20,

ping_timeout: float | None = 20,

close_timeout: float | None = 10,

max_queue: int | None | tuple[int | None, int | None] = 16,

write_limit: int | tuple[int, int | None] = 2**15,

) -> None:

self.protocol: ServerProtocol

super().__init__(

protocol,

ping_interval=ping_interval,

ping_timeout=ping_timeout,

close_timeout=close_timeout,

max_queue=max_queue,

write_limit=write_limit,

)

self.server = server

self.request_rcvd: asyncio.Future[None] = self.loop.create_future()

self.username: str # see basic_auth()

self.handler: Callable[[ServerConnection], Awaitable[None]] # see route()

self.handler_kwargs: Mapping[str, Any] # see route()

def respond(self, status: StatusLike, text: str) -> Response:

"""

Create a plain text HTTP response.

``process_request`` and ``process_response`` may call this method to

return an HTTP response instead of performing the WebSocket opening

handshake.

You can modify the response before returning it, for example by changing

HTTP headers.

Args:

status: HTTP status code.

text: HTTP response body; it will be encoded to UTF-8.

Returns:

HTTP response to send to the client.

"""

return self.protocol.reject(status, text)

async def handshake(

self,

process_request: (

Callable[

[ServerConnection, Request],

Awaitable[Response | None] | Response | None,

]

| None

) = None,

process_response: (

Callable[

[ServerConnection, Request, Response],

Awaitable[Response | None] | Response | None,

]

| None

) = None,

server_header: str | None = SERVER,

) -> None:

"""

Perform the opening handshake.

"""

await asyncio.wait(

[self.request_rcvd, self.connection_lost_waiter],

return_when=asyncio.FIRST_COMPLETED,

)

if self.request is not None:

async with self.send_context(expected_state=CONNECTING):

response = None

if process_request is not None:

try:

response = process_request(self, self.request)

if isinstance(response, Awaitable):

response = await response

except Exception as exc:

self.protocol.handshake_exc = exc

response = self.protocol.reject(

http.HTTPStatus.INTERNAL_SERVER_ERROR,

(

"Failed to open a WebSocket connection.\n"

"See server log for more information.\n"

),

)

if response is None:

if self.server.is_serving():

self.response = self.protocol.accept(self.request)

else:

self.response = self.protocol.reject(

http.HTTPStatus.SERVICE_UNAVAILABLE,

"Server is shutting down.\n",

)

else:

assert isinstance(response, Response) # help mypy

self.response = response

if server_header:

self.response.headers["Server"] = server_header

response = None

if process_response is not None:

try:

response = process_response(self, self.request, self.response)

if isinstance(response, Awaitable):

response = await response

except Exception as exc:

self.protocol.handshake_exc = exc

response = self.protocol.reject(

http.HTTPStatus.INTERNAL_SERVER_ERROR,

(

"Failed to open a WebSocket connection.\n"

"See server log for more information.\n"

),

)

if response is not None:

assert isinstance(response, Response) # help mypy

self.response = response

self.protocol.send_response(self.response)

# self.protocol.handshake_exc is set when the connection is lost before

# receiving a request, when the request cannot be parsed, or when the

# handshake fails, including when process_request or process_response

# raises an exception.

# It isn't set when process_request or process_response sends an HTTP

# response that rejects the handshake.

if self.protocol.handshake_exc is not None:

raise self.protocol.handshake_exc

def process_event(self, event: Event) -> None:

"""

Process one incoming event.

"""

# First event - handshake request.

if self.request is None:

assert isinstance(event, Request)

self.request = event

self.request_rcvd.set_result(None)

# Later events - frames.

else:

super().process_event(event)

def connection_made(self, transport: asyncio.BaseTransport) -> None:

super().connection_made(transport)

"""

WebSocket server returned by :func:`serve`.

This class mirrors the API of :class:`asyncio.Server`.

It keeps track of WebSocket connections in order to close them properly

when shutting down.

Args:

handler: Connection handler. It receives the WebSocket connection,

which is a :class:`ServerConnection`, in argument.

process_request: Intercept the request during the opening handshake.

Return an HTTP response to force the response. Return :obj:`None` to

continue normally. When you force an HTTP 101 Continue response, the

handshake is successful. Else, the connection is aborted.

``process_request`` may be a function or a coroutine.

process_response: Intercept the response during the opening handshake.

Modify the response or return a new HTTP response to force the

response. Return :obj:`None` to continue normally. When you force an

HTTP 101 Continue response, the handshake is successful. Else, the

connection is aborted. ``process_response`` may be a function or a

coroutine.

server_header: Value of the ``Server`` response header.

It defaults to ``"Python/x.y.z websockets/X.Y"``. Setting it to

:obj:`None` removes the header.

open_timeout: Timeout for opening connections in seconds.

:obj:`None` disables the timeout.

logger: Logger for this server.

It defaults to ``logging.getLogger("websockets.server")``.

See the :doc:`logging guide <../../topics/logging>` for details.

"""

def __init__(

self,

handler: Callable[[ServerConnection], Awaitable[None]],

*,

process_request: (

Callable[

[ServerConnection, Request],

Awaitable[Response | None] | Response | None,

]

| None

) = None,

process_response: (

Callable[

[ServerConnection, Request, Response],

Awaitable[Response | None] | Response | None,

]

| None

) = None,

server_header: str | None = SERVER,

open_timeout: float | None = 10,

logger: LoggerLike | None = None,

) -> None:

self.loop = asyncio.get_running_loop()

self.handler = handler

self.process_request = process_request

self.process_response = process_response

self.server_header = server_header

self.open_timeout = open_timeout

if logger is None:

logger = logging.getLogger("websockets.server")

self.logger = logger

# Keep track of active connections.

self.handlers: dict[ServerConnection, asyncio.Task[None]] = {}

# Task responsible for closing the server and terminating connections.

self.close_task: asyncio.Task[None] | None = None

# Completed when the server is closed and connections are terminated.

self.closed_waiter: asyncio.Future[None] = self.loop.create_future()

@property

def connections(self) -> set[ServerConnection]:

"""

Set of active connections.

This property contains all connections that completed the opening

handshake successfully and didn't start the closing handshake yet.

It can be useful in combination with :func:`~broadcast`.

"""

return {connection for connection in self.handlers if connection.state is OPEN}

def wrap(self, server: asyncio.Server) -> None:

"""

Attach to a given :class:`asyncio.Server`.

Since :meth:`~asyncio.loop.create_server` doesn't support injecting a

custom ``Server`` class, the easiest solution that doesn't rely on

private :mod:`asyncio` APIs is to:

- instantiate a :class:`Server`

- give the protocol factory a reference to that instance

- call :meth:`~asyncio.loop.create_server` with the factory

- attach the resulting :class:`asyncio.Server` with this method

"""

self.server = server

for sock in server.sockets:

if sock.family == socket.AF_INET:

name = "%s:%d" % sock.getsockname()

elif sock.family == socket.AF_INET6:

name = "[%s]:%d" % sock.getsockname()[:2]

elif sock.family == socket.AF_UNIX:

name = sock.getsockname()

# In the unlikely event that someone runs websockets over a

# protocol other than IP or Unix sockets, avoid crashing.

else: # pragma: no cover

name = str(sock.getsockname())

self.logger.info("server listening on %s", name)

async def conn_handler(self, connection: ServerConnection) -> None:

"""

Handle the lifecycle of a WebSocket connection.

Since this method doesn't have a caller that can handle exceptions,

it attempts to log relevant ones.

It guarantees that the TCP connection is closed before exiting.

"""

try:

async with asyncio_timeout(self.open_timeout):

try:

await connection.handshake(

self.process_request,

self.process_response,

self.server_header,

)

except asyncio.CancelledError:

connection.transport.abort()

raise

except Exception:

connection.logger.error("opening handshake failed", exc_info=True)

connection.transport.abort()

return

if connection.protocol.state is not OPEN:

# process_request or process_response rejected the handshake.

connection.transport.abort()

return

try:

connection.start_keepalive()

await self.handler(connection)

except Exception:

connection.logger.error("connection handler failed", exc_info=True)

await connection.close(CloseCode.INTERNAL_ERROR)

else:

await connection.close()

except TimeoutError:

# When the opening handshake times out, there's nothing to log.

pass

except Exception: # pragma: no cover

# Don't leak connections on unexpected errors.

connection.transport.abort()

finally:

# Registration is tied to the lifecycle of conn_handler() because

# the server waits for connection handlers to terminate, even if

# all connections are already closed.

del self.handlers[connection]

def start_connection_handler(self, connection: ServerConnection) -> None:

"""

Register a connection with this server.

"""

# The connection must be registered in self.handlers immediately.

# If it was registered in conn_handler(), a race condition could

# happen when closing the server after scheduling conn_handler()

# but before it starts executing.

self.handlers[connection] = self.loop.create_task(self.conn_handler(connection))

def close(self, close_connections: bool = True) -> None:

"""

Close the server.

* Close the underlying :class:`asyncio.Server`.

* When ``close_connections`` is :obj:`True`, which is the default,

close existing connections. Specifically:

* Reject opening WebSocket connections with an HTTP 503 (service

unavailable) error. This happens when the server accepted the TCP

connection but didn't complete the opening handshake before closing.

* Close open WebSocket connections with close code 1001 (going away).

* Wait until all connection handlers terminate.

:meth:`close` is idempotent.

"""

if self.close_task is None:

self.close_task = self.get_loop().create_task(

self._close(close_connections)

)

async def _close(self, close_connections: bool) -> None:

"""

Implementation of :meth:`close`.

This calls :meth:`~asyncio.Server.close` on the underlying

:class:`asyncio.Server` object to stop accepting new connections and

then closes open connections with close code 1001.

"""

self.logger.info("server closing")

# Stop accepting new connections.

self.server.close()

# Wait until all accepted connections reach connection_made() and call

# register(). See https://github.com/python/cpython/issues/79033 for

# details. This workaround can be removed when dropping Python < 3.11.

await asyncio.sleep(0)

if close_connections:

# Close OPEN connections with close code 1001. After server.close(),

# handshake() closes OPENING connections with an HTTP 503 error.

close_tasks = [

asyncio.create_task(connection.close(1001))

for connection in self.handlers

if connection.protocol.state is not CONNECTING

]

# asyncio.wait doesn't accept an empty first argument.

if close_tasks:

await asyncio.wait(close_tasks)

# Wait until all TCP connections are closed.

await self.server.wait_closed()

# Wait until all connection handlers terminate.

# asyncio.wait doesn't accept an empty first argument.

if self.handlers:

await asyncio.wait(self.handlers.values())

# Tell wait_closed() to return.

self.closed_waiter.set_result(None)

self.logger.info("server closed")

async def wait_closed(self) -> None:

"""

Wait until the server is closed.

When :meth:`wait_closed` returns, all TCP connections are closed and

all connection handlers have returned.

To ensure a fast shutdown, a connection handler should always be

awaiting at least one of:

* :meth:`~ServerConnection.recv`: when the connection is closed,

it raises :exc:`~websockets.exceptions.ConnectionClosedOK`;

* :meth:`~ServerConnection.wait_closed`: when the connection is

closed, it returns.

Then the connection handler is immediately notified of the shutdown;

it can clean up and exit.

"""

await asyncio.shield(self.closed_waiter)

def get_loop(self) -> asyncio.AbstractEventLoop:

"""

See :meth:`asyncio.Server.get_loop`.

"""

return self.server.get_loop()

def is_serving(self) -> bool: # pragma: no cover

"""

See :meth:`asyncio.Server.is_serving`.

"""

return self.server.is_serving()

async def start_serving(self) -> None: # pragma: no cover

"""

See :meth:`asyncio.Server.start_serving`.

Typical use::

server = await serve(..., start_serving=False)

# perform additional setup here...

# ... then start the server

await server.start_serving()

"""

await self.server.start_serving()

async def serve_forever(self) -> None: # pragma: no cover

"""

See :meth:`asyncio.Server.serve_forever`.

Typical use::

server = await serve(...)

# this coroutine doesn't return

# canceling it stops the server

await server.serve_forever()

This is an alternative to using :func:`serve` as an asynchronous context

manager. Shutdown is triggered by canceling :meth:`serve_forever`

instead of exiting a :func:`serve` context.

"""

await self.server.serve_forever()

@property

def sockets(self) -> Iterable[socket.socket]:

"""

See :attr:`asyncio.Server.sockets`.

"""

return self.server.sockets

async def __aenter__(self) -> Server: # pragma: no cover

return self

async def __aexit__(

self,

exc_type: type[BaseException] | None,

exc_value: BaseException | None,

traceback: TracebackType | None,

) -> None: # pragma: no cover

self.close()

"""

Create a WebSocket server listening on ``host`` and ``port``.

Whenever a client connects, the server creates a :class:`ServerConnection`,

performs the opening handshake, and delegates to the ``handler`` coroutine.

The handler receives the :class:`ServerConnection` instance, which you can

use to send and receive messages.

Once the handler completes, either normally or with an exception, the server

performs the closing handshake and closes the connection.

This coroutine returns a :class:`Server` whose API mirrors

:class:`asyncio.Server`. Treat it as an asynchronous context manager to

ensure that the server will be closed::

from websockets.asyncio.server import serve

def handler(websocket):

...

# set this future to exit the server

stop = asyncio.get_running_loop().create_future()

async with serve(handler, host, port):

await stop

Alternatively, call :meth:`~Server.serve_forever` to serve requests and

cancel it to stop the server::

server = await serve(handler, host, port)

await server.serve_forever()

Args:

handler: Connection handler. It receives the WebSocket connection,

which is a :class:`ServerConnection`, in argument.

host: Network interfaces the server binds to.

See :meth:`~asyncio.loop.create_server` for details.

port: TCP port the server listens on.

See :meth:`~asyncio.loop.create_server` for details.

origins: Acceptable values of the ``Origin`` header, for defending

against Cross-Site WebSocket Hijacking attacks. Values can be

:class:`str` to test for an exact match or regular expressions

compiled by :func:`re.compile` to test against a pattern. Include

:obj:`None` in the list if the lack of an origin is acceptable.

extensions: List of supported extensions, in order in which they

should be negotiated and run.

subprotocols: List of supported subprotocols, in order of decreasing

preference.

select_subprotocol: Callback for selecting a subprotocol among

those supported by the client and the server. It receives a

:class:`ServerConnection` (not a

:class:`~websockets.server.ServerProtocol`!) instance and a list of

subprotocols offered by the client. Other than the first argument,

it has the same behavior as the

:meth:`ServerProtocol.select_subprotocol

<websockets.server.ServerProtocol.select_subprotocol>` method.

compression: The "permessage-deflate" extension is enabled by default.

Set ``compression`` to :obj:`None` to disable it. See the

:doc:`compression guide <../../topics/compression>` for details.

process_request: Intercept the request during the opening handshake.

Return an HTTP response to force the response or :obj:`None` to

continue normally. When you force an HTTP 101 Continue response, the

handshake is successful. Else, the connection is aborted.

``process_request`` may be a function or a coroutine.

process_response: Intercept the response during the opening handshake.

Return an HTTP response to force the response or :obj:`None` to

continue normally. When you force an HTTP 101 Continue response, the

handshake is successful. Else, the connection is aborted.

``process_response`` may be a function or a coroutine.

server_header: Value of the ``Server`` response header.

It defaults to ``"Python/x.y.z websockets/X.Y"``. Setting it to

:obj:`None` removes the header.

open_timeout: Timeout for opening connections in seconds.

:obj:`None` disables the timeout.

ping_interval: Interval between keepalive pings in seconds.

:obj:`None` disables keepalive.

ping_timeout: Timeout for keepalive pings in seconds.

:obj:`None` disables timeouts.

close_timeout: Timeout for closing connections in seconds.

:obj:`None` disables the timeout.

max_size: Maximum size of incoming messages in bytes.

:obj:`None` disables the limit. You may pass a ``(max_message_size,

max_fragment_size)`` tuple to set different limits for messages and

fragments when you expect long messages sent in short fragments.

max_queue: High-water mark of the buffer where frames are received.

It defaults to 16 frames. The low-water mark defaults to ``max_queue

// 4``. You may pass a ``(high, low)`` tuple to set the high-water

and low-water marks. If you want to disable flow control entirely,

you may set it to ``None``, although that's a bad idea.

write_limit: High-water mark of write buffer in bytes. It is passed to

:meth:`~asyncio.WriteTransport.set_write_buffer_limits`. It defaults

to 32 KiB. You may pass a ``(high, low)`` tuple to set the

high-water and low-water marks.

logger: Logger for this server.

It defaults to ``logging.getLogger("websockets.server")``. See the

:doc:`logging guide <../../topics/logging>` for details.

create_connection: Factory for the :class:`ServerConnection` managing

the connection. Set it to a wrapper or a subclass to customize

connection handling.

Any other keyword arguments are passed to the event loop's

:meth:`~asyncio.loop.create_server` method.

For example:

* You can set ``ssl`` to a :class:`~ssl.SSLContext` to enable TLS.

* You can set ``sock`` to provide a preexisting TCP socket. You may call

:func:`socket.create_server` (not to be confused with the event loop's

:meth:`~asyncio.loop.create_server` method) to create a suitable server

socket and customize it.

* You can set ``start_serving`` to ``False`` to start accepting connections

only after you call :meth:`~Server.start_serving()` or

:meth:`~Server.serve_forever()`.

"""

def __init__(

self,

handler: Callable[[ServerConnection], Awaitable[None]],

host: str | None = None,

port: int | None = None,

*,

# WebSocket

origins: Sequence[Origin | re.Pattern[str] | None] | None = None,

extensions: Sequence[ServerExtensionFactory] | None = None,

subprotocols: Sequence[Subprotocol] | None = None,

select_subprotocol: (

Callable[

[ServerConnection, Sequence[Subprotocol]],

Subprotocol | None,

]

| None

) = None,

compression: str | None = "deflate",

# HTTP

process_request: (

Callable[

[ServerConnection, Request],

Awaitable[Response | None] | Response | None,

]

| None

) = None,

process_response: (

Callable[

[ServerConnection, Request, Response],

Awaitable[Response | None] | Response | None,

]

| None

) = None,

server_header: str | None = SERVER,

# Timeouts

open_timeout: float | None = 10,

ping_interval: float | None = 20,

ping_timeout: float | None = 20,

close_timeout: float | None = 10,

# Limits

max_size: int | None | tuple[int | None, int | None] = 2**20,

max_queue: int | None | tuple[int | None, int | None] = 16,

write_limit: int | tuple[int, int | None] = 2**15,

# Logging

logger: LoggerLike | None = None,

# Escape hatch for advanced customization

create_connection: type[ServerConnection] | None = None,

# Other keyword arguments are passed to loop.create_server

**kwargs: Any,

) -> None:

if subprotocols is not None:

validate_subprotocols(subprotocols)

if compression == "deflate":

extensions = enable_server_permessage_deflate(extensions)

elif compression is not None:

raise ValueError(f"unsupported compression: {compression}")

if create_connection is None:

create_connection = ServerConnection

self.server = Server(

handler,

process_request=process_request,

process_response=process_response,

server_header=server_header,

open_timeout=open_timeout,

logger=logger,

)

if kwargs.get("ssl") is not None:

kwargs.setdefault("ssl_handshake_timeout", open_timeout)

if sys.version_info[:2] >= (3, 11): # pragma: no branch

kwargs.setdefault("ssl_shutdown_timeout", close_timeout)

def factory() -> ServerConnection:

"""

Create an asyncio protocol for managing a WebSocket connection.

"""

# Create a closure to give select_subprotocol access to connection.

protocol_select_subprotocol: (

Callable[

[ServerProtocol, Sequence[Subprotocol]],

Subprotocol | None,

]

| None

) = None

if select_subprotocol is not None:

def protocol_select_subprotocol(

protocol: ServerProtocol,

subprotocols: Sequence[Subprotocol],

) -> Subprotocol | None:

# mypy doesn't know that select_subprotocol is immutable.

assert select_subprotocol is not None

# Ensure this function is only used in the intended context.

assert protocol is connection.protocol

return select_subprotocol(connection, subprotocols)

# This is a protocol in the Sans-I/O implementation of websockets.

protocol = ServerProtocol(

origins=origins,

extensions=extensions,

subprotocols=subprotocols,

select_subprotocol=protocol_select_subprotocol,

max_size=max_size,

logger=logger,

)

# This is a connection in websockets and a protocol in asyncio.

connection = create_connection(

protocol,

self.server,

ping_interval=ping_interval,

ping_timeout=ping_timeout,

close_timeout=close_timeout,

max_queue=max_queue,

write_limit=write_limit,

)

return connection

loop = asyncio.get_running_loop()

if kwargs.pop("unix", False):

self.create_server = loop.create_unix_server(factory, **kwargs)

else:

# mypy cannot tell that kwargs must provide sock when port is None.

self.create_server = loop.create_server(factory, host, port, **kwargs) # type: ignore[arg-type]

# async with serve(...) as ...: ...

async def __aenter__(self) -> Server:

return await self

async def __aexit__(

self,

exc_type: type[BaseException] | None,

exc_value: BaseException | None,

traceback: TracebackType | None,

) -> None:

self.server.close()

await self.server.wait_closed()

# ... = await serve(...)

def __await__(self) -> Generator[Any, None, Server]:

# Create a suitable iterator by calling __await__ on a coroutine.

return self.__await_impl__().__await__()

async def __await_impl__(self) -> Server:

server = await self.create_server

self.server.wrap(server)

return self.server

# ... = yield from serve(...) - remove when dropping Python < 3.10

handler: Callable[[ServerConnection], Awaitable[None]],

path: str | None = None,

**kwargs: Any,

) -> Awaitable[Server]:

"""

Create a WebSocket server listening on a Unix socket.

This function is identical to :func:`serve`, except the ``host`` and

``port`` arguments are replaced by ``path``. It's only available on Unix.

It's useful for deploying a server behind a reverse proxy such as nginx.

Args:

handler: Connection handler. It receives the WebSocket connection,

which is a :class:`ServerConnection`, in argument.

path: File system path to the Unix socket.

"""

try:

username, password = credentials

except (TypeError, ValueError):

return False

else:

realm: str = "",

credentials: tuple[str, str] | Iterable[tuple[str, str]] | None = None,

check_credentials: Callable[[str, str], Awaitable[bool] | bool] | None = None,

) -> Callable[[ServerConnection, Request], Awaitable[Response | None]]:

"""

Factory for ``process_request`` to enforce HTTP Basic Authentication.

:func:`basic_auth` is designed to integrate with :func:`serve` as follows::

from websockets.asyncio.server import basic_auth, serve

async with serve(

...,

process_request=basic_auth(

realm="my dev server",

credentials=("hello", "iloveyou"),

),

):

If authentication succeeds, the connection's ``username`` attribute is set.

If it fails, the server responds with an HTTP 401 Unauthorized status.

One of ``credentials`` or ``check_credentials`` must be provided; not both.

Args:

realm: Scope of protection. It should contain only ASCII characters

because the encoding of non-ASCII characters is undefined. Refer to

section 2.2 of :rfc:`7235` for details.

credentials: Hard coded authorized credentials. It can be a

``(username, password)`` pair or a list of such pairs.

check_credentials: Function or coroutine that verifies credentials.

It receives ``username`` and ``password`` arguments and returns

whether they're valid.

Raises:

TypeError: If ``credentials`` or ``check_credentials`` is wrong.

ValueError: If ``credentials`` and ``check_credentials`` are both

provided or both not provided.

"""

if (credentials is None) == (check_credentials is None):

raise ValueError("provide either credentials or check_credentials")

if credentials is not None:

if is_credentials(credentials):

credentials_list = [cast(tuple[str, str], credentials)]

elif isinstance(credentials, Iterable):

credentials_list = list(cast(Iterable[tuple[str, str]], credentials))

if not all(is_credentials(item) for item in credentials_list):

raise TypeError(f"invalid credentials argument: {credentials}")

else:

raise TypeError(f"invalid credentials argument: {credentials}")

credentials_dict = dict(credentials_list)

def check_credentials(username: str, password: str) -> bool:

try:

expected_password = credentials_dict[username]

except KeyError:

return False

return hmac.compare_digest(expected_password, password)

assert check_credentials is not None # help mypy

async def process_request(

connection: ServerConnection,

request: Request,

) -> Response | None:

"""

Perform HTTP Basic Authentication.

If it succeeds, set the connection's ``username`` attribute and return

:obj:`None`. If it fails, return an HTTP 401 Unauthorized responss.

"""

try:

authorization = request.headers["Authorization"]

except KeyError:

response = connection.respond(

http.HTTPStatus.UNAUTHORIZED,

"Missing credentials\n",

)

response.headers["WWW-Authenticate"] = build_www_authenticate_basic(realm)

return response

try:

username, password = parse_authorization_basic(authorization)

except InvalidHeader:

response = connection.respond(

http.HTTPStatus.UNAUTHORIZED,

"Unsupported credentials\n",

)

response.headers["WWW-Authenticate"] = build_www_authenticate_basic(realm)

return response

valid_credentials = check_credentials(username, password)

if isinstance(valid_credentials, Awaitable):

valid_credentials = await valid_credentials

if not valid_credentials:

response = connection.respond(

http.HTTPStatus.UNAUTHORIZED,

"Invalid credentials\n",

)

response.headers["WWW-Authenticate"] = build_www_authenticate_basic(realm)

return response

connection.username = username

return None