Re: [lwip-users] TCP_LISTEN_BACKLOG setting problem

[Martin Velek]

Probably you want to set the backlog to a value "0", zero. It will
have no effect because of this check.
tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog)
{
  /*...some code...*/
#if TCP_LISTEN_BACKLOG
  lpcb->accepts_pending = 0;
  lpcb->backlog = (backlog ? backlog : 1);
#endif /* TCP_LISTEN_BACKLOG */
/*...some code...*/
}

Obviously zero is not a proper value. Everytime, one client will wait.
If you want only one client, you have to close the listen socket after
accepting a connection and then reopen it. Ugly way, has anyone a
better idea?

Regards
Martin

On 22 February 2011 08:15, Mrutyunjay <address@hidden> wrote:
> hi ,
> I am using lwip (STABLE-1.3.2)  in two different f/w with rtthreads on TI
> luminary processor LM3S6965.
>
> I am not able to restrict listen queue to zero ( I need only one active
> connection on listening socket)
>
> 1. using blocking api .  if i set MAXCLIENT = 0
>
> if i set TCP_LISTEN_BACKLOG 0  , I can see 1 active connection and 8 in
> queue , 9th connection is rejected.
>
> if i set TCP_LISTEN_BACKLOG 1  , I can see 1 active connection and 1 in
> queue.
>
> I am passing  MAXCLIENT for listen queue as follows
>
> listen(server_socket, MAXCLIENT) == -1)  // control the listen queue
> accordingly note use : 0 for blocking 1 for non blocking f/w
>
> ---------------code snippet ---------------
> #define MAXCLIENT            0        // only one active connection.
> #define OFFLINE_PORT      5000  // listen on tcp 5000 port
> if ((server_socket = socket(AF_INET, SOCK_STREAM, 0)) == -1)
> {
>       !sock error handling !
> }
> /* Local Setting to receive connection
>  * initialize the server address (LM Module as Server)
>  */
>     server_addr.sin_family = AF_INET;
>     server_addr.sin_port = htons(OFFLINE_PORT);
>     server_addr.sin_addr.s_addr = INADDR_ANY;
>     rt_memset(&(server_addr.sin_zero),8, sizeof(server_addr.sin_zero));
>
> /* bind the connection on specified port to ANY Local IP address
>  * i.e bind the socket to server address
>  */
>     if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(struct
> sockaddr)) == -1)
>     {
>         /* Bind fails  Error handling !
>     }
>
> /* Listen on Socket
>      * Keep Server on listening mode
>      */
>     if (listen(server_socket, MAXCLIENT) == -1)
>     {
>         // Listen error handling
>     }
> while(1)  //  wait for connection
> {
>
>    //save one level stack
>         sin_size = sizeof(struct sockaddr_in);
>
>         /* connection socket accepts a client request,
>          * this function call is a blocking type
>          */
>         connected = accept(server_socket, (struct sockaddr *)&client_addr,
> &sin_size);
>         /* returns a successful connection socket */
>
>         /* Accept the return of client addr point to client's address
> information*/
>         rt_kprintf("\nI got a connection from (%s , %d)\n",
>         inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
>
>         while(1) // read and process responce from client until disconnected
> or sock error
>         {
>            bytes_received = read_bytes_from_socket(connected,(unsigned char
> *)&request_header.header,sizeof(request_header.header));
>            if(bytes_received <= 0)
>             {
>                lwip_close(connected);
>                break ; // get out of connected loop processing and wait for
> next connection .
>             }
>             else
>             {
>                // process incomming data and respond to clients .
>             }
>         } // end while client connected
>
> }// End  while // wating for conection loop
> ---------------
>
> 2. using non blocking api (select ,read ,write )
>
> if i set TCP_LISTEN_BACKLOG 0 or 1,  I still get 8 queue connections
>
>
>
>
>
>
> Regards,
> Mrutyunjay B Patel
> Regards,
> Mrutyunjay B Patel
>
> _______________________________________________
> lwip-users mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/lwip-users
>