implement automatic login refresh using OIDC refresh tokens

api/src/dooris_api/__init__.py

@@ -3,6 +3,6 @@ from dooris_api.app import app
 
 def main():
     import uvicorn
-    config = uvicorn.Config(app, port=8000, log_level="info")
+    config = uvicorn.Config(app, port=8000, log_level="debug")
     server = uvicorn.Server(config)
     server.run()

api/src/dooris_api/app.py

@@ -1,8 +1,8 @@
 from typing import Optional
 import logging
 import secrets
-import math
-from datetime import datetime, UTC, timedelta
+import sys
+from datetime import datetime, UTC
 from fastapi import FastAPI, Request, Response
 from fastapi.responses import RedirectResponse
 from contextlib import asynccontextmanager
@@ -18,6 +18,12 @@ logger = logging.getLogger(__name__)
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
+    root_logger = logging.getLogger("")
+    root_logger.setLevel(logging.INFO)
+    root_logger.addHandler(logging.StreamHandler(sys.stderr))
+    app_logger = logging.getLogger("dooris_api")
+    app_logger.setLevel(logging.DEBUG)
+    
     app.extra["oidc_client"] = OpenidClient.from_issuer_url(
         url="https://id.hamburg.ccc.de/realms/test/",
         authentication_redirect_uri="http://localhost:8000/auth/login-callback",
@@ -84,25 +90,13 @@ async def login_callback(req: Request, resp: Response, oidc_client: deps.OpenidC
     
     # save the authentication result for later reuse
     if isinstance(auth_result, TokenSuccessResponse):
-        now = datetime.now(UTC)
         auth_start_time = datetime.fromtimestamp(float(req.cookies["auth_start_time"]), UTC)
-
-        # extract the ID token now to validate its authenticity and properly set the cookie lifetime
-        id_token = oidc_client.decode_id_token(auth_result.id_token, nonce=req.cookies["auth_nonce"])
-
-        # calculate how long each token is valid
-        at_max_age = auth_start_time - now + timedelta(seconds=auth_result.expires_in)
-        rt_max_age = auth_start_time - now + timedelta(seconds=auth_result.refresh_expires_in)
-        id_max_age = datetime.fromtimestamp(id_token.exp, UTC) - now
-
-        # update cookies
-        resp.set_cookie("access_token", auth_result.access_token, max_age=int(at_max_age.total_seconds()), httponly=True, secure=True)
-        resp.set_cookie("refresh_token", auth_result.refresh_token, max_age=int(rt_max_age.total_seconds()), httponly=True, secure=True)
-        resp.set_cookie("id_token", auth_result.id_token, max_age=int(id_max_age.total_seconds()), httponly=True, secure=True)
-        resp.set_cookie("auth_nonce", req.cookies["auth_nonce"], max_age=int(id_max_age.total_seconds()), httponly=True, secure=True)
+        deps.persist_auth_state(oidc_client, resp, auth_result, auth_start_time, req.cookies["auth_nonce"])
 
         # redirect the user to the page they wanted to visit
         return {"authenticated": True}
     else:
         return {"authenticated": False, "error": auth_result}
 
+
+

api/src/dooris_api/deps.py

@@ -1,10 +1,16 @@
 from typing import Annotated, Optional
-from fastapi import Request, Depends
+import logging
+from datetime import datetime, UTC, timedelta
+from fastapi import Request, Depends, Response
+from simple_openid_connect.data import TokenSuccessResponse
 from simple_openid_connect.client import OpenidClient
 
 from dooris_api import models
 
 
+logger = logging.getLogger(__name__)
+
+
 async def get_oidc_client(req: Request) -> OpenidClient:
     return req.app.extra["oidc_client"]
 
@@ -12,14 +18,53 @@ async def get_oidc_client(req: Request) -> OpenidClient:
 OpenidClient = Annotated[OpenidClient, Depends(get_oidc_client)]
 
 
-async def get_current_user(req: Request, oidc_client: OpenidClient) -> Optional[models.CurrentUser]:
-    # for now we only handle the case of no expired tokens
-    # TODO: automatically use the refresh token to fetch new access tokens
-    if not all(i in req.cookies for i in ["access_token", "refresh_token", "id_token", "auth_nonce"]):
-        return None
+async def get_current_user(req: Request, resp: Response, oidc_client: OpenidClient) -> Optional[models.CurrentUser]:
+    # easiest case: we still have an access token (which is the most fleeting component)
+    # everything else should still be valid so we can just use it
+    if all(i in req.cookies for i in ("access_token", "id_token", "auth_nonce")):
+        logger.debug("user is fully authenticated, returning current user from existing id_token")
+        id_token = oidc_client.decode_id_token(req.cookies["id_token"], nonce=req.cookies["auth_nonce"])
+        return models.CurrentUser(id_token=id_token)
 
-    id_token = oidc_client.decode_id_token(req.cookies["id_token"], nonce=req.cookies["auth_nonce"])
-    return models.CurrentUser(id_token=id_token)
+    # if we have a refresh token, try to get new tokens
+    if all(i in req.cookies for i in ("refresh_token", "auth_nonce")):
+        logger.debug("user has been previously authenticated, trying to recover with refresh_token")
+        auth_start_time = datetime.now(UTC)
+        token_resp = oidc_client.exchange_refresh_token(req.cookies["refresh_token"])
+        if isinstance(token_resp, TokenSuccessResponse):
+            persist_auth_state(oidc_client, resp, token_resp, auth_start_time)
+
+            # return the newly gotten info
+            id_token = oidc_client.decode_id_token(token_resp.id_token)
+            return models.CurrentUser(id_token=id_token)
+    
+    # otherwise we can't meaningfully recover any user information or the user is simply not authenticated
+    logger.debug("no currently authenticated user")
+    return None
+
+
+def persist_auth_state(oidc_client: OpenidClient, resp: Response, tokens: TokenSuccessResponse, auth_start_time: datetime, token_nonce: Optional[str] = None):
+    now = datetime.now(UTC)
+    
+    # extract the ID token now to validate its authenticity and properly set the cookie lifetime
+    id_token = oidc_client.decode_id_token(tokens.id_token, nonce=token_nonce)
+
+    # calculate how long each token is valid
+    at_max_age = auth_start_time - now + timedelta(seconds=tokens.expires_in)
+    id_max_age = datetime.fromtimestamp(id_token.exp, UTC) - now
+    nonce_max_age = max(at_max_age, id_max_age)
+    if tokens.refresh_token is not None and tokens.refresh_expires_in is not None:
+        rt_max_age = auth_start_time - now + timedelta(seconds=tokens.refresh_expires_in)
+        nonce_max_age = max(at_max_age, rt_max_age, id_max_age)
+    if token_nonce is None:
+        nonce_max_age = timedelta(0)
+
+    # update cookies
+    resp.set_cookie("access_token", tokens.access_token, max_age=int(at_max_age.total_seconds()), httponly=True, secure=True)
+    if tokens.refresh_token is not None and tokens.refresh_expires_in is not None:
+        resp.set_cookie("refresh_token", tokens.refresh_token, max_age=int(rt_max_age.total_seconds()), httponly=True, secure=True)
+    resp.set_cookie("id_token", tokens.id_token, max_age=int(id_max_age.total_seconds()), httponly=True, secure=True)
+    resp.set_cookie("auth_nonce", token_nonce, max_age=int(nonce_max_age.total_seconds()), httponly=True, secure=True)
 
 
 CurrentUser = Annotated[Optional[models.CurrentUser], Depends(get_current_user)]