Files
2020-05-25 08:13:42 +02:00

128 lines
5.0 KiB
Python

import re
from inspect import Parameter, Signature
from typing import Optional, Sequence
from fastapi import Depends, HTTPException, status
from makefun import with_signature
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
INVALID_CHARS_PATTERN = re.compile(r"[^0-9a-zA-Z_]")
INVALID_LEADING_CHARS_PATTERN = re.compile(r"^[^a-zA-Z_]+")
def name_to_variable_name(name: str) -> str:
"""Transform a backend name string into a string safe to use as variable name."""
name = re.sub(INVALID_CHARS_PATTERN, "", name)
name = re.sub(INVALID_LEADING_CHARS_PATTERN, "", name)
return name
class DuplicateBackendNamesError(Exception):
pass
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
# Here comes some blood magic 🧙‍♂️
# Thank to "makefun", we are able to generate callable
# with a dynamic number of dependencies at runtime.
# This way, each security schemes are detected by the OpenAPI generator.
try:
parameters = [
Parameter(
name=name_to_variable_name(backend.name),
kind=Parameter.POSITIONAL_OR_KEYWORD,
default=Depends(backend.scheme), # type: ignore
)
for backend in self.backends
]
signature = Signature(parameters)
except ValueError:
raise DuplicateBackendNamesError()
@with_signature(signature, func_name="get_optional_current_user")
async def get_optional_current_user(*args, **kwargs):
return await self._authenticate(*args, **kwargs)
@with_signature(signature, func_name="get_optional_current_active_user")
async def get_optional_current_active_user(*args, **kwargs):
user = await get_optional_current_user(*args, **kwargs)
if not user or not user.is_active:
return None
return user
@with_signature(signature, func_name="get_optional_current_superuser")
async def get_optional_current_superuser(*args, **kwargs):
user = await get_optional_current_active_user(*args, **kwargs)
if not user or not user.is_superuser:
return None
return user
@with_signature(signature, func_name="get_current_user")
async def get_current_user(*args, **kwargs):
user = await get_optional_current_user(*args, **kwargs)
if user is None:
raise self._get_credentials_exception()
return user
@with_signature(signature, func_name="get_current_active_user")
async def get_current_active_user(*args, **kwargs):
user = await get_optional_current_active_user(*args, **kwargs)
if user is None:
raise self._get_credentials_exception()
return user
@with_signature(signature, func_name="get_current_superuser")
async def get_current_superuser(*args, **kwargs):
user = await get_optional_current_active_user(*args, **kwargs)
if user is None:
raise self._get_credentials_exception()
if not user.is_superuser:
raise self._get_credentials_exception(status.HTTP_403_FORBIDDEN)
return user
self.get_current_user = get_current_user
self.get_current_active_user = get_current_active_user
self.get_current_superuser = get_current_superuser
self.get_optional_current_user = get_optional_current_user
self.get_optional_current_active_user = get_optional_current_active_user
self.get_optional_current_superuser = get_optional_current_superuser
async def _authenticate(self, *args, **kwargs) -> Optional[BaseUserDB]:
for backend in self.backends:
token: str = kwargs[name_to_variable_name(backend.name)]
if token:
user = await backend(token, self.user_db)
if user is not None:
return user
return None
def _get_credentials_exception(
self, status_code: int = status.HTTP_401_UNAUTHORIZED
) -> HTTPException:
return HTTPException(status_code=status_code)