Question

What’s the difference between TCP’s close and TCP’s abort? Following is an example:

..//init the socket FD
while(1)
{
switch(socket_state)
{
case 0:
if(0 != FD)
{
    tcp_connect(FD,rem_ip, 502, 0);
    socket_state = 1;
    break;
}
case 2:
    if(TRUE == wait_ack)
    {
            return;
    }
    ..//sending data
    wait_ack = TRUE;
    break;
case 3:
{
    if(0 != FD)
    {
        tcp_close(FD);   //or tcp_abort(FD);
        tcp_release_socket(FD);
        soc_state = 0;
    }
}
     break;
}

}

tcp_callback:

U16 Listener(U8 socket,U8 event,U8* ptr,U16 par)
switch(event)
{
    case TCP_EVT_CONNECT:
        soc_state = 2;
        break;
    case TCP_EVT_ACK:
        wait_ack = __FALSE;
        break;
    case TCP_EVT_ABORT:
        soc_state = 3;
        break;
}
return (1);

Now, when I shut the server down, my client will receive a TCP_EVT_ABORT message, and set soc_state = 3. In while(1) loop, switch sees this and goes into case 3. Do I want it to close, or abort? In the next loop iteration, I go back to state 0. Why is the file descriptor still not 0?
How can I use abort or close mechnism correctly?

Answer 1

A little hard to understand,When you use tcp_get_socket,then the socket is allocated and its state is TCP_STATE_CLOSED.After that,using tcp_connect to connect remote server.Its state will change to TCP_STATE_SYN_REC.When connection is established,state become TCP_STATE_CONNECT.When server side is shut down,Client side will receive EVENT : TCP_EVT_ABORT. I close current socket using tcp_release_socket. Also when data is sent completed,using this function close socket.Next time ,we should invoke tcp_get_socket before tcp_connect with the old socket. For short,every connection,every tcp_get_socket.