initial from https://gitlab.mim-libre.fr/alphabet/radicale_oauth/-/blob/dev/oauth2/radicale_auth_oauth2/__init__.py

radicale/auth/oauth2.py

@@ -0,0 +1,44 @@
+"""
+Authentication backend that checks credentials against an oauth2 server auth endpoint
+"""
+
+from radicale import auth
+from radicale.log import logger
+import requests
+from requests.utils import quote
+
+
+class Auth(auth.BaseAuth):
+    def __init__(self, configuration):
+        super().__init__(configuration)
+        self._endpoint = configuration.get("auth", "oauth2_token_endpoint")
+        logger.warning("Using oauth2 token endpoint: %s" % (self._endpoint))
+
+    def login(self, login, password):
+        """Validate credentials.
+        Sends login credentials to oauth auth endpoint and checks that a token is returned
+        """
+        try:
+            # authenticate to authentication endpoint and return login if ok, else ""
+            req_params = {
+                "username": login,
+                "password": password,
+                "grant_type": "password",
+                "client_id": "radicale",
+            }
+            req_headers = {"Content-Type": "application/x-www-form-urlencoded"}
+            response = requests.post(
+                self._endpoint, data=req_params, headers=req_headers
+            )
+            if (
+                response.status_code == requests.codes.ok
+                and "access_token" in response.json()
+            ):
+                return login
+        except OSError as e:
+            raise RuntimeError(
+                "Failed to authenticate against oauth server %r: %s"
+                % (self._endpoint, e)
+            ) from e
+        logger.warning("User %s failed to authenticate" % (str(login)))
+        return ""