如何在C ++中设置登录超时？

Question

I'm writing a timeout for a simple login on a server written in C++. Well, this is the code:

char username[this->BUFSIZE];
    clean(username);
    char password[this->BUFSIZE];
    clean(password);
    send(client_fd, "USER", 4, 0);

    //Start timer
    time_t end,start;
    double dif;
    time (&start);

    recv(client_fd,username,BUFSIZE,0);
    send(client_fd, "PASS", 4, 0);
    recv(client_fd,password,BUFSIZE,0);

    //End timer
    time (&end);
    dif = difftime (end,start);
            //If dif>10 seconds disconnect the client.
    if(dif>10)
        close(client_fd);

Ok it works fine, but there is just a problem: the disconnect happens only when the client end typing user + password. My goal is that the timer must close the connection at 10 seconds, independently if the client did the login or not.

Is it possible? Thank you!

Answer 1

You can use select() to wait for data on client_fd . select supports a timeout value and will return 0 if the timeout occurs. If data is ready, select will return the number of descriptors with data pending.

Answer 2

You can also set the socket option SO_RCVTIMEO with a timeval structure. This will cause recv to return once the timeout has happened.

Answer 3

Use a signal - SIGALRM, set this before entering recv and when it triggers close the connection.

Alternatively use a full-fat framework such as asio, which will provide timers etc.