Fix #42: multiple authentication backends (#47)

* Revamp authentication to allow multiple backends

* Make router generate a login route for each backend

* Apply black

* Remove unused imports

* Complete docstrings

* Update documentation

* WIP add cookie auth

* Complete cookie auth unit tests

* Add documentation for cookie auth

* Fix cookie backend default name

* Don't make cookie return a Response

fastapi_users/authentication/__init__.py

@@ -1,2 +1,60 @@
+from typing import Sequence
+
+from fastapi import HTTPException
+from starlette import status
+from starlette.requests import Request
+
 from fastapi_users.authentication.base import BaseAuthentication  # noqa: F401
+from fastapi_users.authentication.cookie import CookieAuthentication  # noqa: F401
 from fastapi_users.authentication.jwt import JWTAuthentication  # noqa: F401
+from fastapi_users.db import BaseUserDatabase
+from fastapi_users.models import BaseUserDB
+
+
+class Authenticator:
+    """
+    Provides dependency callables to retrieve authenticated user.
+
+    It performs the authentication against a list of backends
+    defined by the end-developer. The first backend yielding a user wins.
+    If no backend yields a user, an HTTPException is raised.
+
+    :param backends: List of authentication backends.
+    :param user_db: Database adapter instance.
+    """
+
+    backends: Sequence[BaseAuthentication]
+    user_db: BaseUserDatabase
+
+    def __init__(
+        self, backends: Sequence[BaseAuthentication], user_db: BaseUserDatabase
+    ):
+        self.backends = backends
+        self.user_db = user_db
+
+    async def get_current_user(self, request: Request) -> BaseUserDB:
+        return await self._authenticate(request)
+
+    async def get_current_active_user(self, request: Request) -> BaseUserDB:
+        user = await self.get_current_user(request)
+        if not user.is_active:
+            raise self._get_credentials_exception()
+        return user
+
+    async def get_current_superuser(self, request: Request) -> BaseUserDB:
+        user = await self.get_current_active_user(request)
+        if not user.is_superuser:
+            raise self._get_credentials_exception(status.HTTP_403_FORBIDDEN)
+        return user
+
+    async def _authenticate(self, request: Request) -> BaseUserDB:
+        for backend in self.backends:
+            user = await backend(request, self.user_db)
+            if user is not None:
+                return user
+        raise self._get_credentials_exception()
+
+    def _get_credentials_exception(
+        self, status_code: int = status.HTTP_401_UNAUTHORIZED
+    ) -> HTTPException:
+        return HTTPException(status_code=status_code)