Re: [lwip-users] help request; need to get a grip of lwIP

[mcondarelli]

Real sorry.
I sent the message before it was finished.
Continuation follows below.

Regards
Mauro

----- Messaggio originale -----
> Hi,
> I'm struggling with my first lwIP port.
> I need to implement a few services, mostly based on TCP.
> 
> One of the first things I need to do is to create a socket to allow
> remote to connect, when this happens I should start sending some
> logging messages over the socket.
> If none is connected messages are silently discarded.
> 
> My real problem is to get to the first stage of the connection.
> 
> For some tests I used apps/tcpecho_raw as template.
> 
> My main program calls (no prior lwIP code) the function IP_start(0).
> 
> ---------------------------------------------------------------
> struct netif netif;
> 
> /* static port number; workaround for lwIP slipif deficencies */
> int slipif_port = -1;
> 
> static void ip_init(void *param)
> {
> IP4_ADDR(&gw, 192, 168, 0, 1);
> IP4_ADDR(&ipaddr, 192, 168, 0, 2);
> IP4_ADDR(&netmask, 255, 255, 255, 0);
> 
> netif_add(&netif, &ipaddr, &netmask, &gw, NULL, slipif_init,
> tcpip_input);
> nmea_init();
> }
> 
> error_t IP_start(u8_t port)
> {
> if (slipif_port != -1)
> {
> main_debug_printf("IP_start: already initialized!\r\n");
> return FAILURE;
> }
> slipif_port = port;
> 
> tcpip_init(ip_init, NULL);
> return SUCCESS;
> }
> ---------------------------------------------------------------
> nmea_init() is the function that initializes my application
> ---------------------------------------------------------------
---------------------------------------------------------------
void nmea_init(void)
{
   LWIP_DEBUGF(N_DEBUG, ("nmea_init: start\r\n"));
   nmea_pcb = tcp_new();
   if (nmea_pcb != NULL)
   {
      err_t err;

      err = tcp_bind(nmea_pcb, IP_ADDR_ANY, 1000);
      if (err == ERR_OK)
      {
         LWIP_DEBUGF(N_DEBUG, ("nmea_init: bound\r\n"));

         nmea_pcb = tcp_listen(nmea_pcb);
         tcp_accept(nmea_pcb, nmea_accept);
         LWIP_DEBUGF(N_DEBUG, ("nmea_init: waiting for connection\r\n"));
      }
      else
      {
         LWIP_DEBUGF(N_DEBUG, ("nmea_init: unable to bind\r\n"));
      }
   }
   else
   {
      LWIP_DEBUGF(N_DEBUG, ("nmea_init: unable to allocate pcb\r\n"));
   }
}
---------------------------------------------------------------
The function nmea_accept() is never called.
I traced the error down to lwip/core/ipv4/ip.c where the test:
---------------------------------------------------------------
      /* interface is up and configured? */
      if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) {
        /* unicast to this interface address? */
        if (ip_addr_cmp(&current_iphdr_dest, &(netif->ip_addr)) ||
            /* or broadcast on this interface network address? */
            ip_addr_isbroadcast(&current_iphdr_dest, netif)) {
          LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface 
%c%c\n",
              netif->name[0], netif->name[1]));
          /* break out of for loop */
          break;
        }
---------------------------------------------------------------
fails because netif_is_up(netif) returns FALSE.

Struct netif appears to contain the right values, but I'm obviously missing 
some needed initialization.

Can someone point me to some complete initialization fitting my cases?
I will try debugging through the code and I believe I can find out which 
function does the required initialization, but it's far from being an efficient 
process.

I really need to get a grip on the various programming interfaces lwIP has, 
possibly mixing them in a sensible way.

I will need to implement several semi-unrelated services all insisting on the 
same SLIP connection; some of them are best suited for the RAW interface while 
some other would prefer a connection; is it possible to mix (on different 
applications, of course)?

TiA
Mauro