Revised the routes in the examples in README.rst.

README.rst

@@ -6,12 +6,30 @@ Flask HTTP Digest Authentication
 Description
 ===========
 
-*Flask-Digest-Auth* is an HTTP Digest Authentication implementation
+*Flask-Digest-Auth* is an `HTTP Digest Authentication`_ implementation
 for Flask_ applications.  It authenticates the user for the protected
-views.  It works with Flask-Login_, so that log in protection can be
-separated with the authentication mechanism.  You can write Flask
-modules that work with different authentication mechanisms.
+views.
 
+HTTP Digest Authentication is specified in `RFC 2617`_.
+
+HTTP Digest Authentication has the advantage that it does not send the
+actual password to the server, which greatly enhances the security.
+It uses the challenge-response authentication scheme.  The client
+returns the response calculated from the challenge and the password,
+but not the original password.
+
+Log in forms has the advantage of freedom, in the senses of both the
+visual design and the actual implementation.  You may implement your
+own challenge-response log in form, but then you are reinventing the
+wheels.  If a pretty log in form is not critical to your project, HTTP
+Digest Authentication should be a good choice.
+
+Flask-Digest-Auth works with Flask-Login_.  Log in protection can be
+separated with the authentication mechanism.  You can create protected
+Flask modules without knowing the actual authentication mechanisms.
+
+.. _HTTP Digest Authentication: https://en.wikipedia.org/wiki/Digest_access_authentication
+.. _RFC 2617: https://www.rfc-editor.org/rfc/rfc2617
 .. _Flask: https://flask.palletsprojects.com
 .. _Flask-Login: https://flask-login.readthedocs.io
 
@@ -19,14 +37,14 @@ modules that work with different authentication mechanisms.
 Installation
 ============
 
-It's suggested that you install with ``pip``:
+You can install Flask-Digest-Auth with ``pip``:
 
 ::
 
-    pip install flask-digest-auth
+    pip install Flask-Digest-Auth
 
 You may also install the latest source from the
-`flask-digest-auth Github repository`_.
+`Flask-Digest-Auth GitHub repository`_.
 
 ::
 
@@ -34,7 +52,7 @@ You may also install the latest source from the
     cd flask-digest-auth
     pip install .
 
-.. _flask-digest-auth Github repository: https://github.com/imacat/flask-digest-auth
+.. _Flask-Digest-Auth GitHub repository: https://github.com/imacat/flask-digest-auth
 
 
 Flask-Digest-Auth Alone
@@ -50,7 +68,7 @@ In your ``my_app.py``:
 
 ::
 
-    from flask import Flask
+    from flask import Flask, request, redirect
     from flask_digest_auth import DigestAuth
 
     app: flask = Flask(__name__)
@@ -71,13 +89,19 @@ In your ``my_app.py``:
     def admin():
         ... (Process the view) ...
 
+    @app.post("/logout")
+    @auth.login_required
+    def logout():
+        auth.logout()
+        return redirect(request.form.get("next"))
+
 
 Example for Larger Applications with ``create_app()`` with Flask-Digest-Auth Alone
 ----------------------------------------------------------------------------------
 
 In your ``my_app/__init__.py``:
 
-:::
+::
 
     from flask import Flask
     from flask_digest_auth import DigestAuth
@@ -105,15 +129,21 @@ In your ``my_app/views.py``:
 ::
 
     from my_app import auth
-    from flask import Flask, Blueprint
+    from flask import Flask, Blueprint, request, redirect
 
     bp = Blueprint("admin", __name__, url_prefix="/admin")
 
-    @bp.get("/")
+    @bp.get("/admin")
     @auth.login_required
     def admin():
         ... (Process the view) ...
 
+    @app.post("/logout")
+    @auth.login_required
+    def logout():
+        auth.logout()
+        return redirect(request.form.get("next"))
+
     def init_app(app: Flask) -> None:
         app.register_blueprint(bp)
 
@@ -134,7 +164,7 @@ In your ``my_app.py``:
 
 ::
 
-    from flask import Flask
+    from flask import Flask, request, redirect
     from flask_digest_auth import DigestAuth
     from flask_login import LoginManager
 
@@ -160,18 +190,27 @@ In your ``my_app.py``:
     def admin():
         ... (Process the view) ...
 
+    @app.post("/logout")
+    @flask_login.login_required
+    def logout():
+        auth.logout()
+        # Do not call flask_login.logout_user()
+        return redirect(request.form.get("next"))
+
 
 Example for Larger Applications with ``create_app()`` with Flask-Login Integration
 ----------------------------------------------------------------------------------
 
 In your ``my_app/__init__.py``:
 
-:::
+::
 
     from flask import Flask
     from flask_digest_auth import DigestAuth
     from flask_login import LoginManager
 
+    auth: DigestAuth = DigestAuth()
+
     def create_app(test_config = None) -> Flask:
         app: flask = Flask(__name__)
         ... (Configure the Flask application) ...
@@ -183,7 +222,7 @@ In your ``my_app/__init__.py``:
         def load_user(user_id: str) -> t.Optional[User]:
             ... (Load the user with the username) ...
 
-        auth: DigestAuth = DigestAuth(realm=app.config["REALM"])
+        auth.realm = app.config["REALM"]
         auth.init_app(app)
 
         @auth.register_get_password
@@ -197,23 +236,56 @@ In your ``my_app/views.py``:
 ::
 
     import flask_login
-    from flask import Flask, Blueprint
+    from flask import Flask, Blueprint, request, redirect
+    from my_app import auth
 
     bp = Blueprint("admin", __name__, url_prefix="/admin")
 
-    @bp.get("/")
+    @bp.get("/admin")
     @flask_login.login_required
     def admin():
         ... (Process the view) ...
 
+    @app.post("/logout")
+    @flask_login.login_required
+    def logout():
+        auth.logout()
+        # Do not call flask_login.logout_user()
+        return redirect(request.form.get("next"))
+
     def init_app(app: Flask) -> None:
         app.register_blueprint(bp)
 
-The views only depend on Flask-Login, but not its underlying
-authentication mechanism.  You can always change the
-authentication mechanism without changing the views, or release a
-protected Flask module without specifying the authentication
-mechanism.
+The views only depend on Flask-Login, but not the actual
+authentication mechanism.  You can change the actual authentication
+mechanism without changing the views.
+
+
+Setting the Password Hash
+=========================
+
+The password hash of the HTTP Digest Authentication is composed of the
+realm, the username, and the password.  Example for setting the
+password:
+
+::
+
+    from flask_digest_auth import make_password_hash
+
+    user.password = make_password_hash(realm, username, password)
+
+The username is part of the hash.  If the user changes their username,
+you need to ask their password, to generate and store the new password
+hash.
+
+
+Log Out
+=======
+
+Call ``auth.logout()`` when the user wants to log out.
+Besides the usual log out routine, ``auth.logout()`` actually causes
+the next browser automatic authentication to fail, forcing the browser
+to ask the user for the username and password again.
 
 
 Writing Tests

src/flask_digest_auth/auth.py

@@ -27,7 +27,8 @@ from functools import wraps
 from random import random
 from secrets import token_urlsafe
 
-from flask import g, request, Response, session, abort, Flask, Request
+from flask import g, request, Response, session, abort, Flask, Request, \
+    current_app
 from itsdangerous import URLSafeTimedSerializer, BadData
 from werkzeug.datastructures import Authorization
 
@@ -112,6 +113,9 @@ class DigestAuth:
         :return: None.
         :raise UnauthorizedException: When the authentication failed.
         """
+        if "digest_auth_logout" in session:
+            del session["digest_auth_logout"]
+            raise UnauthorizedException("Logging out")
         authorization: Authorization = request.authorization
         if self.use_opaque:
             if authorization.opaque is None:
@@ -252,6 +256,24 @@ class DigestAuth:
             raise ModuleNotFoundError(
                 "init_app() is only for Flask-Login integration")
 
+    @staticmethod
+    def logout() -> None:
+        """Logs out the user.
+        This actually causes the next authentication to fail, which forces
+        the browser to ask the user for the username and password again.
+
+        :return: None.
+        """
+        if "user" in session:
+            del session["user"]
+        try:
+            if hasattr(current_app, "login_manager"):
+                from flask_login import logout_user
+                logout_user()
+        except ModuleNotFoundError:
+            pass
+        session["digest_auth_logout"] = True
+
 
 class AuthState:
     """The authorization state."""

src/flask_digest_auth/test.py

@@ -49,14 +49,14 @@ class Client(WerkzeugClient):
             return response
         if hasattr(g, "_login_user"):
             delattr(g, "_login_user")
-        auth_data: Authorization = self.__class__.__make_authorization(
+        auth_data: Authorization = self.__class__.make_authorization(
             www_authenticate, args[0], digest_auth[0], digest_auth[1])
         response = super(Client, self).open(*args, auth=auth_data, **kwargs)
         return response
 
     @staticmethod
-    def __make_authorization(www_authenticate: WWWAuthenticate, uri: str,
-                             username: str, password: str) -> Authorization:
+    def make_authorization(www_authenticate: WWWAuthenticate, uri: str,
+                           username: str, password: str) -> Authorization:
         """Composes and returns the request authorization.
 
         :param www_authenticate: The WWW-Authenticate response.

tests/test_auth.py

@@ -22,8 +22,9 @@ import typing as t
 from secrets import token_urlsafe
 from types import SimpleNamespace
 
-from flask import Response, Flask, g
+from flask import Response, Flask, g, redirect, request
 from flask_testing import TestCase
+from werkzeug.datastructures import WWWAuthenticate, Authorization
 
 from flask_digest_auth import DigestAuth, make_password_hash, Client
 
@@ -70,24 +71,34 @@ class AuthenticationTestCase(TestCase):
             return SimpleNamespace(username=username) if username in user_db \
                 else None
 
-        @app.get("/login-required-1/auth", endpoint="auth-1")
+        @app.get("/admin-1/auth", endpoint="admin-1")
         @auth.login_required
-        def login_required_1() -> str:
-            """The first dummy view.
+        def admin_1() -> str:
+            """The first administration section.
 
             :return: The response.
             """
             return f"Hello, {g.user.username}! #1"
 
-        @app.get("/login-required-2/auth", endpoint="auth-2")
+        @app.get("/admin-2/auth", endpoint="admin-2")
         @auth.login_required
-        def login_required_2() -> str:
-            """The second dummy view.
+        def admin_2() -> str:
+            """The second administration section.
 
             :return: The response.
             """
             return f"Hello, {g.user.username}! #2"
 
+        @app.post("/logout", endpoint="logout")
+        @auth.login_required
+        def logout() -> redirect:
+            """Logs out the user.
+
+            :return: The response.
+            """
+            auth.logout()
+            return redirect(request.form.get("next"))
+
         return app
 
     def test_auth(self) -> None:
@@ -95,14 +106,90 @@ class AuthenticationTestCase(TestCase):
 
         :return: None.
         """
-        response: Response = self.client.get(self.app.url_for("auth-1"))
+        response: Response = self.client.get(self.app.url_for("admin-1"))
         self.assertEqual(response.status_code, 401)
         response = self.client.get(
-            self.app.url_for("auth-1"), digest_auth=(_USERNAME, _PASSWORD))
+            self.app.url_for("admin-1"), digest_auth=(_USERNAME, _PASSWORD))
         self.assertEqual(response.status_code, 200)
         self.assertEqual(response.data.decode("UTF-8"),
                          f"Hello, {_USERNAME}! #1")
-        response: Response = self.client.get(self.app.url_for("auth-2"))
+        response: Response = self.client.get(self.app.url_for("admin-2"))
         self.assertEqual(response.status_code, 200)
         self.assertEqual(response.data.decode("UTF-8"),
                          f"Hello, {_USERNAME}! #2")
+
+    def test_stale_opaque(self) -> None:
+        """Tests the stale and opaque value.
+
+        :return: None.
+        """
+        admin_uri: str = self.app.url_for("admin-1")
+        response: Response
+        www_authenticate: WWWAuthenticate
+        auth_data: Authorization
+
+        response = super(Client, self.client).get(admin_uri)
+        self.assertEqual(response.status_code, 401)
+        www_authenticate = response.www_authenticate
+        self.assertEqual(www_authenticate.type, "digest")
+        self.assertEqual(www_authenticate.stale, None)
+        opaque: str = www_authenticate.opaque
+
+        www_authenticate.nonce = "bad"
+        auth_data = Client.make_authorization(
+            www_authenticate, admin_uri, _USERNAME, _PASSWORD)
+        response = super(Client, self.client).get(admin_uri, auth=auth_data)
+        self.assertEqual(response.status_code, 401)
+        www_authenticate = response.www_authenticate
+        self.assertEqual(www_authenticate.stale, True)
+        self.assertEqual(www_authenticate.opaque, opaque)
+
+        auth_data = Client.make_authorization(
+            www_authenticate, admin_uri, _USERNAME, _PASSWORD + "2")
+        response = super(Client, self.client).get(admin_uri, auth=auth_data)
+        self.assertEqual(response.status_code, 401)
+        www_authenticate = response.www_authenticate
+        self.assertEqual(www_authenticate.stale, False)
+        self.assertEqual(www_authenticate.opaque, opaque)
+
+        auth_data = Client.make_authorization(
+            www_authenticate, admin_uri, _USERNAME, _PASSWORD)
+        response = super(Client, self.client).get(admin_uri, auth=auth_data)
+        self.assertEqual(response.status_code, 200)
+
+    def test_logout(self) -> None:
+        """Tests the logging out.
+
+        :return: None.
+        """
+        admin_uri: str = self.app.url_for("admin-1")
+        logout_uri: str = self.app.url_for("logout")
+        response: Response
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 401)
+
+        response = self.client.get(admin_uri,
+                                   digest_auth=(_USERNAME, _PASSWORD))
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.post(logout_uri, data={"next": admin_uri})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.location, admin_uri)
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 401)
+
+        response = self.client.get(admin_uri,
+                                   digest_auth=(_USERNAME, _PASSWORD))
+        self.assertEqual(response.status_code, 401)
+
+        response = self.client.get(admin_uri,
+                                   digest_auth=(_USERNAME, _PASSWORD))
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 200)

tests/test_flask_login.py

@@ -21,8 +21,9 @@
 import typing as t
 from secrets import token_urlsafe
 
-from flask import Response, Flask
+from flask import Response, Flask, g, redirect, request
 from flask_testing import TestCase
+from werkzeug.datastructures import WWWAuthenticate, Authorization
 
 from flask_digest_auth import DigestAuth, make_password_hash, Client
 
@@ -32,7 +33,13 @@ _PASSWORD: str = "Circle Of Life"
 
 
 class User:
+    """A dummy user."""
+
     def __init__(self, username: str):
+        """Constructs a dummy user.
+
+        :param username: The username.
+        """
         self.username: str = username
         self.is_authenticated: bool = True
         self.is_active: bool = True
@@ -96,24 +103,34 @@ class FlaskLoginTestCase(TestCase):
             """
             return User(user_id) if user_id in user_db else None
 
-        @app.get("/login-required-1/auth", endpoint="auth-1")
+        @app.get("/admin-1/auth", endpoint="admin-1")
         @flask_login.login_required
-        def login_required_1() -> str:
-            """The first dummy view.
+        def admin_1() -> str:
+            """The first administration section.
 
             :return: The response.
             """
             return f"Hello, {flask_login.current_user.username}! #1"
 
-        @app.get("/login-required-2/auth", endpoint="auth-2")
+        @app.get("/admin-2/auth", endpoint="admin-2")
         @flask_login.login_required
-        def login_required_2() -> str:
-            """The second dummy view.
+        def admin_2() -> str:
+            """The second administration section.
 
             :return: The response.
             """
             return f"Hello, {flask_login.current_user.username}! #2"
 
+        @app.post("/logout", endpoint="logout")
+        @flask_login.login_required
+        def logout() -> redirect:
+            """Logs out the user.
+
+            :return: The response.
+            """
+            auth.logout()
+            return redirect(request.form.get("next"))
+
         return app
 
     def test_auth(self) -> None:
@@ -124,14 +141,99 @@ class FlaskLoginTestCase(TestCase):
         if not self.has_flask_login:
             self.skipTest("Skipped testing Flask-Login integration without it.")
 
-        response: Response = self.client.get(self.app.url_for("auth-1"))
+        response: Response = self.client.get(self.app.url_for("admin-1"))
         self.assertEqual(response.status_code, 401)
         response = self.client.get(
-            self.app.url_for("auth-1"), digest_auth=(_USERNAME, _PASSWORD))
+            self.app.url_for("admin-1"), digest_auth=(_USERNAME, _PASSWORD))
         self.assertEqual(response.status_code, 200)
         self.assertEqual(response.data.decode("UTF-8"),
                          f"Hello, {_USERNAME}! #1")
-        response: Response = self.client.get(self.app.url_for("auth-2"))
+        response: Response = self.client.get(self.app.url_for("admin-2"))
         self.assertEqual(response.status_code, 200)
         self.assertEqual(response.data.decode("UTF-8"),
                          f"Hello, {_USERNAME}! #2")
+
+    def test_stale_opaque(self) -> None:
+        """Tests the stale and opaque value.
+
+        :return: None.
+        """
+        if not self.has_flask_login:
+            self.skipTest("Skipped testing Flask-Login integration without it.")
+
+        admin_uri: str = self.app.url_for("admin-1")
+        response: Response
+        www_authenticate: WWWAuthenticate
+        auth_data: Authorization
+
+        response = super(Client, self.client).get(admin_uri)
+        self.assertEqual(response.status_code, 401)
+        www_authenticate = response.www_authenticate
+        self.assertEqual(www_authenticate.type, "digest")
+        self.assertEqual(www_authenticate.stale, None)
+        opaque: str = www_authenticate.opaque
+
+        if hasattr(g, "_login_user"):
+            delattr(g, "_login_user")
+        www_authenticate.nonce = "bad"
+        auth_data = Client.make_authorization(
+            www_authenticate, admin_uri, _USERNAME, _PASSWORD)
+        response = super(Client, self.client).get(admin_uri, auth=auth_data)
+        self.assertEqual(response.status_code, 401)
+        www_authenticate = response.www_authenticate
+        self.assertEqual(www_authenticate.stale, True)
+        self.assertEqual(www_authenticate.opaque, opaque)
+
+        if hasattr(g, "_login_user"):
+            delattr(g, "_login_user")
+        auth_data = Client.make_authorization(
+            www_authenticate, admin_uri, _USERNAME, _PASSWORD + "2")
+        response = super(Client, self.client).get(admin_uri, auth=auth_data)
+        self.assertEqual(response.status_code, 401)
+        www_authenticate = response.www_authenticate
+        self.assertEqual(www_authenticate.stale, False)
+        self.assertEqual(www_authenticate.opaque, opaque)
+
+        if hasattr(g, "_login_user"):
+            delattr(g, "_login_user")
+        auth_data = Client.make_authorization(
+            www_authenticate, admin_uri, _USERNAME, _PASSWORD)
+        response = super(Client, self.client).get(admin_uri, auth=auth_data)
+        self.assertEqual(response.status_code, 200)
+
+    def test_logout(self) -> None:
+        """Tests the logging out.
+
+        :return: None.
+        """
+        admin_uri: str = self.app.url_for("admin-1")
+        logout_uri: str = self.app.url_for("logout")
+        response: Response
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 401)
+
+        response = self.client.get(admin_uri,
+                                   digest_auth=(_USERNAME, _PASSWORD))
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.post(logout_uri, data={"next": admin_uri})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.location, admin_uri)
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 401)
+
+        response = self.client.get(admin_uri,
+                                   digest_auth=(_USERNAME, _PASSWORD))
+        self.assertEqual(response.status_code, 401)
+
+        response = self.client.get(admin_uri,
+                                   digest_auth=(_USERNAME, _PASSWORD))
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.get(admin_uri)
+        self.assertEqual(response.status_code, 200)