Crude OpenID Connect client using Authlib

Developers can go to /sso/login to get redirected to the SSO. On
successful login, the ID token is displayed.

Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>

aurweb/routers/sso.py

@@ -0,0 +1,30 @@
+import fastapi
+
+from authlib.integrations.starlette_client import OAuth
+from starlette.requests import Request
+
+import aurweb.config
+
+router = fastapi.APIRouter()
+
+oauth = OAuth()
+oauth.register(
+    name="sso",
+    server_metadata_url=aurweb.config.get("sso", "openid_configuration"),
+    client_kwargs={"scope": "openid"},
+    client_id=aurweb.config.get("sso", "client_id"),
+    client_secret=aurweb.config.get("sso", "client_secret"),
+)
+
+
+@router.get("/sso/login")
+async def login(request: Request):
+    redirect_uri = aurweb.config.get("options", "aur_location") + "/sso/authenticate"
+    return await oauth.sso.authorize_redirect(request, redirect_uri, prompt="login")
+
+
+@router.get("/sso/authenticate")
+async def authenticate(request: Request):
+    token = await oauth.sso.authorize_access_token(request)
+    user = await oauth.sso.parse_id_token(request, token)
+    return dict(user)