infinite loop with future c++

I have this code and it gives me an infinite loop as the state of the future is always NOT ready even though the function inside it is finished. I checked the respond function and it always end but the state is never changed to ready.

/**
    this class simulate a driver response to the future 
*/
class driver {
    bool response;
    int time;
public:
    driver(bool response, int time) : response(response), time(time) {}

    bool respond() {
        this_thread::sleep_for(std::chrono::milliseconds(time));
        return response;
    }
};


int check_response(vector<driver> &ds) {
    auto f1 = std::async(std::launch::async, [&]() {
        return ds[0].respond();
    });

    auto f2 = std::async(std::launch::async, [&]() {
        return ds[1].respond();
    });

    auto state1 = f1.wait_for(5ms);
    auto state2 = f2.wait_for(5ms);
    while (
        (state1 != future_status::ready)
        &&
        (state2 != future_status::ready)
        ) {
            auto state1 = f1.wait_for(5ms);
            auto state2 = f2.wait_for(5ms);
           // never exits this loop
    }

    if (state1 == future_status::ready && f1.get()) {
        return 0;
    }
    else if (state2 == future_status::ready && f2.get()) {
        return 1;
    }
    else {
        return -1;
    }
}


int main() {
    vector<driver> ds{
        {true,300},
        {true,10}
    };
    cout << check_response(ds);
}