471 lines
16 KiB
Python
471 lines
16 KiB
Python
# The Flask HTTP Digest Authentication Project.
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# Author: imacat@mail.imacat.idv.tw (imacat), 2022/10/22
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# Copyright (c) 2022 imacat.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""The HTTP Digest Authentication.
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See RFC 2617 HTTP Authentication: Basic and Digest Access Authentication
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"""
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from __future__ import annotations
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import sys
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import typing as t
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from functools import wraps
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from secrets import token_urlsafe, randbits
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from flask import g, request, Response, session, abort, Flask, Request
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from itsdangerous import URLSafeTimedSerializer, BadData
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from werkzeug.datastructures import Authorization
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from flask_digest_auth.algo import calc_response
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class DigestAuth:
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"""The HTTP digest authentication."""
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def __init__(self, realm: t.Optional[str] = None):
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"""Constructs the HTTP digest authentication.
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:param realm: The realm.
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"""
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self.__serializer: URLSafeTimedSerializer \
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= URLSafeTimedSerializer(token_urlsafe(32))
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self.realm: str = "" if realm is None else realm
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"""The realm. Default is an empty string."""
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self.algorithm: t.Optional[t.Literal["MD5", "MD5-sess"]] = None
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"""The algorithm, either None, ``MD5``, or ``MD5-sess``. Default is
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None."""
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self.use_opaque: bool = True
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"""Whether to use an opaque. Default is True."""
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self.__domain: t.List[str] = []
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"""A list of directories that this username and password applies to.
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Default is empty."""
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self.__qop: t.List[t.Literal["auth", "auth-int"]] \
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= ["auth", "auth-int"]
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"""A list of supported quality of protection supported, either
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``qop``, ``auth-int``, both, or empty. Default is both."""
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self.app: t.Optional[Flask] = None
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"""The current Flask application."""
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self.__get_password_hash: BasePasswordHashGetter \
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= BasePasswordHashGetter()
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self.__get_user: BaseUserGetter = BaseUserGetter()
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self.__on_login: BaseOnLogInCallback = BaseOnLogInCallback()
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def login_required(self, view) -> t.Callable:
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"""The view decorator for HTTP digest authentication.
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:Example:
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::
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@app.get("/admin")
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@auth.login_required
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def admin():
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return f"Hello, {g.user.username}!"
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The logged-in user can be retrieved at ``g.user``.
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:param view: The view.
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:return: The login-protected view.
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"""
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class NoLogInException(Exception):
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"""The exception thrown when the user is not authorized."""
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def get_logged_in_user() -> t.Any:
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"""Returns the currently logged-in user.
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:return: The currently logged-in user.
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:raise NoLogInException: When the user is not logged in.
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"""
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if "user" not in session:
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raise NoLogInException
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user: t.Optional[t.Any] = self.__get_user(session["user"])
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if user is None:
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del session["user"]
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raise NoLogInException
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return user
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def auth_user(state: AuthState) -> t.Any:
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"""Authenticates a user.
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:param state: The authentication state.
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:return: The user.
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:raise UnauthorizedException: When the authentication fails.
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"""
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authorization: Authorization = request.authorization
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if authorization is None:
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raise UnauthorizedException
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if authorization.type != "digest":
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raise UnauthorizedException(
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"Not an HTTP digest authorization")
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self.__authenticate(state)
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session["user"] = authorization.username
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return self.__get_user(authorization.username)
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@wraps(view)
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def login_required_view(*args, **kwargs) -> t.Any:
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"""The login-protected view.
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:param args: The positional arguments of the view.
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:param kwargs: The keyword arguments of the view.
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:return: The response.
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"""
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try:
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g.user = get_logged_in_user()
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return view(*args, **kwargs)
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except NoLogInException:
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pass
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state: AuthState = AuthState()
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try:
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g.user = auth_user(state)
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self.__on_login(g.user)
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return view(*args, **kwargs)
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except UnauthorizedException as e:
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if len(e.args) > 0:
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sys.stderr.write(e.args[0] + "\n")
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response: Response = Response()
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response.status = 401
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response.headers["WWW-Authenticate"] \
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= self.__make_response_header(state)
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abort(response)
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return login_required_view
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def __authenticate(self, state: AuthState) -> None:
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"""Authenticate a user.
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:param state: The authorization state.
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:return: None.
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:raise UnauthorizedException: When the authentication failed.
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"""
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if "digest_auth_logout" in session:
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del session["digest_auth_logout"]
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raise UnauthorizedException("Logging out")
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authorization: Authorization = request.authorization
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if self.use_opaque:
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if authorization.opaque is None:
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raise UnauthorizedException(
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"Missing \"opaque\" in the Authorization header")
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try:
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self.__serializer.loads(
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authorization.opaque, salt="opaque", max_age=1800)
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except BadData:
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raise UnauthorizedException("Invalid opaque")
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state.opaque = authorization.opaque
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password_hash: t.Optional[str] \
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= self.__get_password_hash(authorization.username)
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if password_hash is None:
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raise UnauthorizedException(
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f"No such user \"{authorization.username}\"")
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expected: str = calc_response(
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method=request.method, uri=authorization.uri,
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password_hash=password_hash, nonce=authorization.nonce,
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qop=authorization.qop,
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algorithm=authorization.get("algorithm"),
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cnonce=authorization.cnonce, nc=authorization.nc,
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body=request.data)
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if authorization.response != expected:
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state.stale = False
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raise UnauthorizedException("Incorrect response value")
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try:
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self.__serializer.loads(
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authorization.nonce,
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salt="nonce" if authorization.opaque is None
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else f"nonce-{authorization.opaque}")
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except BadData:
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state.stale = True
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raise UnauthorizedException("Invalid nonce")
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def __make_response_header(self, state: AuthState) -> str:
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"""Composes and returns the ``WWW-Authenticate`` response header.
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:param state: The authorization state.
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:return: The ``WWW-Authenticate`` response header.
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"""
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def get_opaque() -> t.Optional[str]:
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"""Returns the opaque value.
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:return: The opaque value.
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"""
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if not self.use_opaque:
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return None
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if state.opaque is not None:
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return state.opaque
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return self.__serializer.dumps(randbits(32), salt="opaque")
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opaque: t.Optional[str] = get_opaque()
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nonce: str = self.__serializer.dumps(
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randbits(32),
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salt="nonce" if opaque is None else f"nonce-{opaque}")
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header: str = f"Digest realm=\"{self.realm}\""
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if len(self.__domain) > 0:
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domain_list: str = ",".join(self.__domain)
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header += f", domain=\"{domain_list}\""
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header += f", nonce=\"{nonce}\""
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if opaque is not None:
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header += f", opaque=\"{opaque}\""
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if state.stale is not None:
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header += f", stale=TRUE" if state.stale else f", stale=FALSE"
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if self.algorithm is not None:
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header += f", algorithm=\"{self.algorithm}\""
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if len(self.__qop) > 0:
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qop_list: str = ",".join(self.__qop)
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header += f", qop=\"{qop_list}\""
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return header
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def register_get_password(self, func: t.Callable[[str], t.Optional[str]])\
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-> None:
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"""The decorator to register the callback to obtain the password hash.
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:Example:
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::
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@auth.register_get_password
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def get_password_hash(username: str) -> Optional[str]:
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user = User.query.filter(User.username == username).first()
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return None if user is None else user.password
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:param func: The callback that given the username, returns the password
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hash, or None if the user does not exist.
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:return: None.
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"""
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class PasswordHashGetter(BasePasswordHashGetter):
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"""The base password hash getter."""
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@staticmethod
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def __call__(username: str) -> t.Optional[str]:
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"""Returns the password hash of a user.
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:param username: The username.
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:return: The password hash, or None if the user does not exist.
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"""
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return func(username)
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self.__get_password_hash = PasswordHashGetter()
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def register_get_user(self, func: t.Callable[[str], t.Optional[t.Any]])\
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-> None:
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"""The decorator to register the callback to obtain the user.
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:Example:
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::
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@auth.register_get_user
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def get_user(username: str) -> Optional[User]:
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return User.query.filter(User.username == username).first()
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:param func: The callback that given the username, returns the user,
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or None if the user does not exist.
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:return: None.
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"""
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class UserGetter(BaseUserGetter):
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"""The user getter."""
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@staticmethod
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def __call__(username: str) -> t.Optional[t.Any]:
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"""Returns a user.
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:param username: The username.
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:return: The user, or None if the user does not exist.
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"""
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return func(username)
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self.__get_user = UserGetter()
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def register_on_login(self, func: t.Callable[[t.Any], None]) -> None:
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"""The decorator to register the callback to run when the user logs in.
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:Example:
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::
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@auth.register_on_login
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def on_login(user: User) -> None:
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user.visits = user.visits + 1
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:param func: The callback given the logged-in user.
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:return: None.
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"""
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class OnLogInCallback:
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"""The callback when the user logs in."""
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@staticmethod
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def __call__(user: t.Any) -> None:
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"""Runs the callback when the user logs in.
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:param user: The logged-in user.
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:return: None.
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"""
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func(user)
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self.__on_login = OnLogInCallback()
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def init_app(self, app: Flask) -> None:
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"""Initializes the Flask application.
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:Example:
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::
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app: flask = Flask(__name__)
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auth: DigestAuth = DigestAuth()
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auth.realm = "My Admin"
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auth.init_app(app)
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:param app: The Flask application.
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:return: None.
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"""
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app.digest_auth = self
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self.app = app
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if hasattr(app, "login_manager"):
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from flask_login import LoginManager, login_user
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login_manager: LoginManager = getattr(app, "login_manager")
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@login_manager.unauthorized_handler
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def unauthorized() -> None:
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"""Handles when the user is unauthorized.
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:return: None.
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"""
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response: Response = Response()
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response.status = 401
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response.headers["WWW-Authenticate"] \
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= self.__make_response_header(g.digest_auth_state)
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abort(response)
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@login_manager.request_loader
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def load_user_from_request(req: Request) -> t.Optional[t.Any]:
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"""Loads the user from the request header.
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:param req: The request.
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:return: The authenticated user, or None if the
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authentication fails
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"""
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g.digest_auth_state = AuthState()
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authorization: Authorization = req.authorization
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try:
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if authorization is None:
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raise UnauthorizedException
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if authorization.type != "digest":
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raise UnauthorizedException(
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"Not an HTTP digest authorization")
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self.__authenticate(g.digest_auth_state)
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user = login_manager.user_callback(
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authorization.username)
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login_user(user)
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self.__on_login(user)
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return user
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except UnauthorizedException as e:
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if str(e) != "":
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app.logger.warning(str(e))
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return None
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def logout(self) -> None:
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"""Logs out the user.
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This actually causes the next authentication to fail, which forces
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the browser to ask the user for the username and password again.
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:Example:
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::
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@app.post("/logout")
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@auth.login_required
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def logout():
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auth.logout()
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return redirect(request.form.get("next"))
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:return: None.
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"""
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if "user" in session:
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del session["user"]
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try:
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if hasattr(self.app, "login_manager"):
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from flask_login import logout_user
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logout_user()
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except ModuleNotFoundError:
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pass
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session["digest_auth_logout"] = True
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class AuthState:
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"""The authorization state."""
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def __init__(self):
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"""Constructs the authorization state."""
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self.opaque: t.Optional[str] = None
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self.stale: t.Optional[bool] = None
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class UnauthorizedException(Exception):
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"""The exception thrown when the authentication is failed."""
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pass
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class BasePasswordHashGetter:
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"""The base password hash getter."""
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@staticmethod
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def __call__(username: str) -> t.Optional[str]:
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"""Returns the password hash of a user.
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:param username: The username.
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:return: The password hash, or None if the user does not exist.
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:raise UnboundLocalError: When the password hash getter function is
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not registered yet.
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"""
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raise UnboundLocalError("The function to return the password hash"
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" was not registered yet.")
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class BaseUserGetter:
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"""The base user getter."""
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@staticmethod
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def __call__(username: str) -> t.Optional[t.Any]:
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"""Returns a user.
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:param username: The username.
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:return: The user, or None if the user does not exist.
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:raise UnboundLocalError: When the user getter function is not
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registered yet.
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"""
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raise UnboundLocalError("The function to return the user"
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" was not registered yet.")
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class BaseOnLogInCallback:
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"""The base callback when the user logs in."""
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@staticmethod
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def __call__(user: t.Any) -> None:
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"""Runs the callback when the user logs in.
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:param user: The logged-in user.
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:return: None.
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"""
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