Revised the login_required method of the DigestAuth class for readability.

.gitignore

@@ -23,11 +23,13 @@ dist
 .pytest_cache
 venv
 
-flask_session
-instance
-
 .DS_Store
 .idea
+
+instance
+flask_session
+
 .scannerwork
+sonar-project.properties
 
 excludes

src/flask_digest_auth/algo.py

@@ -61,6 +61,16 @@ def calc_response(
         cnonce or nc is missing with the auth or auth-int qop.
     """
 
+    def validate_required(field: t.Optional[str], error: str) -> None:
+        """Validates a required field.
+
+        :param field: The field that is required.
+        :param error: The error message.
+        :return: None.
+        """
+        if field is None:
+            raise UnauthorizedException(error)
+
     def calc_ha1() -> str:
         """Calculates and returns the first hash.
 
@@ -68,16 +78,13 @@ def calc_response(
         :raise UnauthorizedException: When the cnonce is missing with the MD5-sess
             algorithm.
         """
-        if algorithm is None or algorithm == "MD5":
-            return password_hash
         if algorithm == "MD5-sess":
-            if cnonce is None:
-                raise UnauthorizedException(
-                    f"Missing \"cnonce\" with algorithm=\"{algorithm}\"")
+            validate_required(
+                cnonce, f"Missing \"cnonce\" with algorithm=\"{algorithm}\"")
             return md5(f"{password_hash}:{nonce}:{cnonce}".encode("utf8")) \
                 .hexdigest()
-        raise UnauthorizedException(
-            f"Unsupported algorithm=\"{algorithm}\"")
+        # algorithm is None or algorithm == "MD5"
+        return password_hash
 
     def calc_ha2() -> str:
         """Calculates the second hash.
@@ -86,30 +93,20 @@ def calc_response(
         :raise UnauthorizedException: When the body is missing with
             qop="auth-int".
         """
-        if qop is None or qop == "auth":
-            return md5(f"{method}:{uri}".encode("utf8")).hexdigest()
         if qop == "auth-int":
-            if body is None:
-                raise UnauthorizedException(
-                    f"Missing \"body\" with qop=\"{qop}\"")
+            validate_required(body, f"Missing \"body\" with qop=\"{qop}\"")
             return md5(
                 f"{method}:{uri}:{md5(body).hexdigest()}".encode("utf8")) \
                 .hexdigest()
-        raise UnauthorizedException(f"Unsupported qop=\"{qop}\"")
+        # qop is None or qop == "auth"
+        return md5(f"{method}:{uri}".encode("utf8")).hexdigest()
 
     ha1: str = calc_ha1()
     ha2: str = calc_ha2()
-    if qop is None:
-        return md5(f"{ha1}:{nonce}:{ha2}".encode("utf8")).hexdigest()
     if qop == "auth" or qop == "auth-int":
-        if cnonce is None:
-            raise UnauthorizedException(
-                f"Missing \"cnonce\" with the qop=\"{qop}\"")
-        if nc is None:
-            raise UnauthorizedException(
-                f"Missing \"nc\" with the qop=\"{qop}\"")
+        validate_required(cnonce, f"Missing \"cnonce\" with the qop=\"{qop}\"")
+        validate_required(nc, f"Missing \"nc\" with the qop=\"{qop}\"")
         return md5(f"{ha1}:{nonce}:{nc}:{cnonce}:{qop}:{ha2}".encode("utf8"))\
             .hexdigest()
-    if cnonce is None:
-        raise UnauthorizedException(
-            f"Unsupported qop=\"{qop}\"")
+    # qop is None
+    return md5(f"{ha1}:{nonce}:{ha2}".encode("utf8")).hexdigest()

src/flask_digest_auth/auth.py

@@ -110,6 +110,36 @@ class DigestAuth:
         class NoLogInException(Exception):
             """The exception thrown when the user is not authorized."""
 
+        def get_logged_in_user() -> t.Optional[t.Any]:
+            """Returns the currently logged-in user.
+
+            :return: The currently logged-in user.
+            :raise NoLogInException: When the user is not logged in.
+            """
+            if "user" not in session:
+                raise NoLogInException
+            user: t.Optional[t.Any] = self.__get_user(session["user"])
+            if user is None:
+                raise NoLogInException
+            return user
+
+        def auth_user(state: AuthState) -> t.Any:
+            """Authenticates a user.
+
+            :param state: The authentication state.
+            :return: The user.
+            :raise UnauthorizedException: When the authentication fails.
+            """
+            authorization: Authorization = request.authorization
+            if authorization is None:
+                raise UnauthorizedException
+            if authorization.type != "digest":
+                raise UnauthorizedException(
+                    "Not an HTTP digest authorization")
+            self.authenticate(state)
+            session["user"] = authorization.username
+            return self.__get_user(authorization.username)
+
         @wraps(view)
         def login_required_view(*args, **kwargs) -> t.Any:
             """The login-protected view.
@@ -119,36 +149,24 @@ class DigestAuth:
             :return: The response.
             """
             try:
-                if "user" not in session:
-                    raise NoLogInException
-                user: t.Optional[t.Any] = self.__get_user(session["user"])
-                if user is None:
-                    raise NoLogInException
-                g.user = user
+                g.user = get_logged_in_user()
                 return view(*args, **kwargs)
             except NoLogInException:
-                state: AuthState = AuthState()
-                authorization: Authorization = request.authorization
-                try:
-                    if authorization is None:
-                        raise UnauthorizedException
-                    if authorization.type != "digest":
-                        raise UnauthorizedException(
-                            "Not an HTTP digest authorization")
-                    self.authenticate(state)
-                    session["user"] = authorization.username
-                    user = self.__get_user(authorization.username)
-                    g.user = user
-                    self.__on_login(user)
-                    return view(*args, **kwargs)
-                except UnauthorizedException as e:
-                    if len(e.args) > 0:
-                        sys.stderr.write(e.args[0] + "\n")
-                    response: Response = Response()
-                    response.status = 401
-                    response.headers["WWW-Authenticate"] \
-                        = self.make_response_header(state)
-                    abort(response)
+                pass
+
+            state: AuthState = AuthState()
+            try:
+                g.user = auth_user(state)
+                self.__on_login(g.user)
+                return view(*args, **kwargs)
+            except UnauthorizedException as e:
+                if len(e.args) > 0:
+                    sys.stderr.write(e.args[0] + "\n")
+                response: Response = Response()
+                response.status = 401
+                response.headers["WWW-Authenticate"] \
+                    = self.make_response_header(state)
+                abort(response)
 
         return login_required_view
 
@@ -203,9 +221,19 @@ class DigestAuth:
         :param state: The authorization state.
         :return: The WWW-Authenticate response header.
         """
-        opaque: t.Optional[str] = None if not self.use_opaque else \
-            (state.opaque if state.opaque is not None
-             else self.serializer.dumps(randbits(32), salt="opaque"))
+
+        def get_opaque() -> t.Optional[str]:
+            """Returns the opaque value.
+
+            :return: The opaque value.
+            """
+            if not self.use_opaque:
+                return None
+            if state.opaque is not None:
+                return state.opaque
+            return self.serializer.dumps(randbits(32), salt="opaque")
+
+        opaque: t.Optional[str] = get_opaque()
         nonce: str = self.serializer.dumps(
             randbits(32),
             salt="nonce" if opaque is None else f"nonce-{opaque}")

src/flask_digest_auth/test.py

@@ -66,9 +66,8 @@ class Client(WerkzeugClient):
         :return: The request authorization.
         """
         qop: t.Optional[t.Literal["auth", "auth-int"]] = None
-        if www_authenticate.qop is not None:
-            if "auth" in www_authenticate.qop:
-                qop = "auth"
+        if www_authenticate.qop is not None and "auth" in www_authenticate.qop:
+            qop = "auth"
 
         cnonce: t.Optional[str] = None
         if qop is not None or www_authenticate.algorithm == "MD5-sess":