Retrieving client properties before adding it

Flower Help - Beginners
1

Is there a way to pass some information to the server so that the server can reject the client within the SimpleClientManager.register method?

When I try this example with flower 1.12.0, the client.get_properties(...) call hangs indefinitely:

# client
import flwr as fl


class FlowerClient(fl.client.NumPyClient):
    def get_properties(
        self, config: dict[str, bool | bytes | float | int | str]
    ) -> dict[str, bool | bytes | float | int | str]:
        res = {
            "msg": "hello",
        }
        return res


fl.client.start_client(
    server_address="localhost:8080",
    client=FlowerClient().to_client(),
)

# server
import flwr as fl
from flwr.server.client_proxy import ClientProxy
from flwr.common import GetPropertiesIns
from flwr.server.client_manager import SimpleClientManager


class ClientManager(SimpleClientManager):

    def register(self, client: ClientProxy) -> bool:
        # Here, the properties are not populated (which would already solve the problem)
        print("Registering client", client, client.properties)

        # Calling get_properties hangs
        print(client.get_properties(GetPropertiesIns({}), None, None))
        return super().register(client)


fl.server.start_server(
    server_address="0.0.0.0:8080",
    config=fl.server.ServerConfig(num_rounds=1),
    client_manager=ClientManager(),
)