Ensure that identity provider is used for auth,

even in websockets (but only if those inherit from JupyterHandler,
and if they do not fallback to previous implementation and warn).

jupyter_server/base/handlers.py

@@ -589,7 +589,7 @@ def check_host(self) -> bool:
             )
         return allow
 
-    async def prepare(self) -> Awaitable[None] | None:  # type:ignore[override]
+    async def prepare(self, *, _redirect_to_login=True) -> Awaitable[None] | None:  # type:ignore[override]
         """Prepare a response."""
         # Set the current Jupyter Handler context variable.
         CallContext.set(CallContext.JUPYTER_HANDLER, self)
@@ -636,9 +636,18 @@ async def prepare(self) -> Awaitable[None] | None:  # type:ignore[override]
                 raise HTTPError(403)
             method = getattr(self, self.request.method.lower())
             if not getattr(method, "__allow_unauthenticated", False):
-                # reuse `web.authenticated` logic, which redirects to the login
-                # page on GET and HEAD and otherwise raises 403
-                return web.authenticated(lambda _: super().prepare)(self)
+                if _redirect_to_login:
+                    # reuse `web.authenticated` logic, which redirects to the login
+                    # page on GET and HEAD and otherwise raises 403
+                    return web.authenticated(lambda _: super().prepare())(self)
+                else:
+                    # raise 403 if user is not known without redirecting to login page
+                    user = self.current_user
+                    if user is None:
+                        self.log.warning(
+                            f"Couldn't authenticate {self.__class__.__name__} connection"
+                        )
+                        raise web.HTTPError(403)
 
         return super().prepare()
 
@@ -736,7 +745,7 @@ def write_error(self, status_code: int, **kwargs: Any) -> None:
 class APIHandler(JupyterHandler):
     """Base class for API handlers"""
 
-    async def prepare(self) -> None:
+    async def prepare(self) -> None:  # type:ignore[override]
         """Prepare an API response."""
         await super().prepare()
         if not self.check_origin():
@@ -848,7 +857,7 @@ def options(self, *args: Any, **kwargs: Any) -> None:
 class Template404(JupyterHandler):
     """Render our 404 template"""
 
-    async def prepare(self) -> None:
+    async def prepare(self) -> None:  # type:ignore[override]
         """Prepare a 404 response."""
         await super().prepare()
         raise web.HTTPError(404)

jupyter_server/base/websocket.py

@@ -1,11 +1,15 @@
 """Base websocket classes."""
 import re
+import warnings
 from typing import Optional, no_type_check
 from urllib.parse import urlparse
 
 from tornado import ioloop, web
 from tornado.iostream import IOStream
 
+from jupyter_server.base.handlers import JupyterHandler
+from jupyter_server.utils import JupyterServerAuthWarning
+
 # ping interval for keeping websockets alive (30 seconds)
 WS_PING_INTERVAL = 30000
 
@@ -84,7 +88,10 @@ def clear_cookie(self, *args, **kwargs):
 
     @no_type_check
     def _maybe_auth(self):
-        """Verify authentication if required"""
+        """Verify authentication if required.
+
+        Only used when the websocket class does not inherit from JupyterHandler.
+        """
         if not self.settings.get("allow_unauthenticated_access", False):
             if not self.request.method:
                 raise web.HTTPError(403)
@@ -100,8 +107,18 @@ def _maybe_auth(self):
     @no_type_check
     def prepare(self, *args, **kwargs):
         """Handle a get request."""
-        self._maybe_auth()
-        return super().prepare(*args, **kwargs)
+        if not isinstance(self, JupyterHandler):
+            should_authenticate = not self.settings.get("allow_unauthenticated_access", False)
+            if "identity_provider" in self.settings and should_authenticate:
+                warnings.warn(
+                    "WebSocketMixin sub-class does not inherit from JupyterHandler"
+                    " preventing proper authentication using custom identity provider.",
+                    JupyterServerAuthWarning,
+                    stacklevel=2,
+                )
+            self._maybe_auth()
+            return super().prepare(*args, **kwargs)
+        return super().prepare(*args, **kwargs, _redirect_to_login=False)
 
     @no_type_check
     def open(self, *args, **kwargs):

tests/base/test_websocket.py

@@ -11,9 +11,10 @@
 
 from jupyter_server.auth import IdentityProvider, User
 from jupyter_server.auth.decorator import allow_unauthenticated
+from jupyter_server.base.handlers import JupyterHandler
 from jupyter_server.base.websocket import WebSocketMixin
 from jupyter_server.serverapp import ServerApp
-from jupyter_server.utils import url_path_join
+from jupyter_server.utils import JupyterServerAuthWarning, url_path_join
 
 
 class MockHandler(WebSocketMixin, WebSocketHandler):
@@ -66,11 +67,15 @@ async def test_ping_client_timeout(mixin):
         mixin.write_message("hello")
 
 
-class NoAuthRulesWebsocketHandler(MockHandler):
+class MockJupyterHandler(MockHandler, JupyterHandler):
     pass
 
 
-class PermissiveWebsocketHandler(MockHandler):
+class NoAuthRulesWebsocketHandler(MockJupyterHandler):
+    pass
+
+
+class PermissiveWebsocketHandler(MockJupyterHandler):
     @allow_unauthenticated
     def get(self, *args, **kwargs) -> None:
         return super().get(*args, **kwargs)
@@ -148,5 +153,38 @@ def fetch():
     iidp = IndiscriminateIdentityProvider()
     # should allow access with the user set be the identity provider
     with patch.dict(jp_serverapp.web_app.settings, {"identity_provider": iidp}):
-        res = await fetch()
-        assert res.code == 200
+        ws = await fetch()
+        ws.close()
+
+
+class PermissivePlainWebsocketHandler(MockHandler):
+    # note: inherits from MockHandler not MockJupyterHandler
+    @allow_unauthenticated
+    def get(self, *args, **kwargs) -> None:
+        return super().get(*args, **kwargs)
+
+
+@pytest.mark.parametrize(
+    "jp_server_config",
+    [
+        {
+            "ServerApp": {
+                "allow_unauthenticated_access": False,
+                "identity_provider": IndiscriminateIdentityProvider(),
+            }
+        }
+    ],
+)
+async def test_websocket_auth_warns_mixin_lacks_jupyter_handler(jp_serverapp, jp_ws_fetch):
+    app: ServerApp = jp_serverapp
+    app.web_app.add_handlers(
+        ".*$",
+        [(url_path_join(app.base_url, "permissive"), PermissivePlainWebsocketHandler)],
+    )
+
+    with pytest.warns(
+        JupyterServerAuthWarning,
+        match="WebSocketMixin sub-class does not inherit from JupyterHandler",
+    ):
+        ws = await jp_ws_fetch("permissive", headers={"Authorization": ""})
+        ws.close()