Function server

example/netcat_timeout.cpp:30–39

}

task<> server(uint16_t port) {
    acceptor ac{inet_address{port}};
    // 限时2s，只接受一个 client
    int sockfd = co_await timeout(ac.accept(), 2s);
    if (sockfd >= 0) {
        co_spawn(session(Socket{sockfd}));
    } else {
        log_error(-sockfd);
    }
}

task<> client(std::string_view hostname, uint16_t port) {
    inet_address addr;