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from __future__ import annotations
import functools
import hmac
import http
from typing import Any, Awaitable, Callable, Iterable, Optional, Tuple, Union, cast
from ..datastructures import Headers
from ..exceptions import InvalidHeader
from ..headers import build_www_authenticate_basic, parse_authorization_basic
from .server import HTTPResponse, WebSocketServerProtocol
__all__ = ["BasicAuthWebSocketServerProtocol", "basic_auth_protocol_factory"]
Credentials = Tuple[str, str]
def is_credentials(value: Any) -> bool:
try:
username, password = value
except (TypeError, ValueError):
return False
else:
return isinstance(username, str) and isinstance(password, str)
class BasicAuthWebSocketServerProtocol(WebSocketServerProtocol):
"""
WebSocket server protocol that enforces HTTP Basic Auth.
"""
realm: str = ""
"""
Scope of protection.
If provided, it should contain only ASCII characters because the
encoding of non-ASCII characters is undefined.
"""
username: Optional[str] = None
"""Username of the authenticated user."""
def __init__(
self,
*args: Any,
realm: Optional[str] = None,
check_credentials: Optional[Callable[[str, str], Awaitable[bool]]] = None,
**kwargs: Any,
) -> None:
if realm is not None:
self.realm = realm # shadow class attribute
self._check_credentials = check_credentials
super().__init__(*args, **kwargs)
async def check_credentials(self, username: str, password: str) -> bool:
"""
Check whether credentials are authorized.
This coroutine may be overridden in a subclass, for example to
authenticate against a database or an external service.
Args:
username: HTTP Basic Auth username.
password: HTTP Basic Auth password.
Returns:
bool: :obj:`True` if the handshake should continue;
:obj:`False` if it should fail with an HTTP 401 error.
"""
if self._check_credentials is not None:
return await self._check_credentials(username, password)
return False
async def process_request(
self,
path: str,
request_headers: Headers,
) -> Optional[HTTPResponse]:
"""
Check HTTP Basic Auth and return an HTTP 401 response if needed.
"""
try:
authorization = request_headers["Authorization"]
except KeyError:
return (
http.HTTPStatus.UNAUTHORIZED,
[("WWW-Authenticate", build_www_authenticate_basic(self.realm))],
b"Missing credentials\n",
)
try:
username, password = parse_authorization_basic(authorization)
except InvalidHeader:
return (
http.HTTPStatus.UNAUTHORIZED,
[("WWW-Authenticate", build_www_authenticate_basic(self.realm))],
b"Unsupported credentials\n",
)
if not await self.check_credentials(username, password):
return (
http.HTTPStatus.UNAUTHORIZED,
[("WWW-Authenticate", build_www_authenticate_basic(self.realm))],
b"Invalid credentials\n",
)
self.username = username
return await super().process_request(path, request_headers)
def basic_auth_protocol_factory(
realm: Optional[str] = None,
credentials: Optional[Union[Credentials, Iterable[Credentials]]] = None,
check_credentials: Optional[Callable[[str, str], Awaitable[bool]]] = None,
create_protocol: Optional[Callable[..., BasicAuthWebSocketServerProtocol]] = None,
) -> Callable[..., BasicAuthWebSocketServerProtocol]:
"""
Protocol factory that enforces HTTP Basic Auth.
:func:`basic_auth_protocol_factory` is designed to integrate with
:func:`~websockets.server.serve` like this::
websockets.serve(
...,
create_protocol=websockets.basic_auth_protocol_factory(
realm="my dev server",
credentials=("hello", "iloveyou"),
)
)
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: Coroutine that verifies credentials.
It receives ``username`` and ``password`` arguments
and returns a :class:`bool`. One of ``credentials`` or
``check_credentials`` must be provided but not both.
create_protocol: Factory that creates the protocol. By default, this
is :class:`BasicAuthWebSocketServerProtocol`. It can be replaced
by a subclass.
Raises:
TypeError: If the ``credentials`` or ``check_credentials`` argument is
wrong.
"""
if (credentials is None) == (check_credentials is None):
raise TypeError("provide either credentials or check_credentials")
if credentials is not None:
if is_credentials(credentials):
credentials_list = [cast(Credentials, credentials)]
elif isinstance(credentials, Iterable):
credentials_list = list(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)
async 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)
if create_protocol is None:
create_protocol = BasicAuthWebSocketServerProtocol
return functools.partial(
create_protocol,
realm=realm,
check_credentials=check_credentials,
)
|
