[lwip-users] Multicast Example?

[Jonathan Ross]

I'm using lwip 1.3.0 and I'm using it in raw mode (as provided in Xilinx EDK 11.1/11.4 - I had to change a .tcl script though to include igmp.c).

Using the code below I can see an IGMP join message exit my device and enter the switch its plugged into, but the router in charge of IGMP does not subsequently list my device/interface as being subscribed to the multicast group 239.253.1.1. The IGMP join message it sends out also has a lot of trailing zeros that I don't see when I issue a similar IGMP join from my workstation (OS X 10.6), and also unlike my workstation and other desktops at work, lwIP sends out a single IGMP join, and all other device send 2 or 3 (any idea why?). Also, whenever the IGMP Membership Query message is sent out, my device does not re-issue a join to 239.253.1.1. Did I do something wrong? Below is the code.

int main() {

struct netif *netif, server_netif;

struct ip_addr ipaddr, netmask, gw, ipgroup;

unsigned char mac_ethernet_address[] = { /* REDACTED */ };

err_t igmp_result;

netif = &server_netif;

        init_platform();

/* initliaze IP addresses to be used */

IP4_ADDR( &ipaddr, 10,  10,  12,  58 );

IP4_ADDR( &gw,      10,  10,  12, 254 );

IP4_ADDR( &netmask, 255, 255, 255,   0 );

IP4_ADDR( &ipgroup, 239, 253,   1,   1 );

print_ip_settings(&ipaddr, &netmask, &gw);

lwip_init();

netif->flags |= NETIF_FLAG_IGMP; // This has no effect as netif->flags is zeroed by netif_add when called in xemac_add... 

// but netif has conditional statements based on the value... so I'm confused.

   /* Add network interface to the netif_list, and set it as default */

if (!xemac_add(netif, &ipaddr, &netmask, &gw, mac_ethernet_address, PLATFORM_EMAC_BASEADDR)) {

xil_printf("Error adding N/W interface\n\r");

return -1;

}

netif_set_default(netif);

/* now enable interrupts */

platform_enable_interrupts();

/* specify that the network if is up */

netif_set_up( netif );

/* start the application (web server, rxtest, txtest, etc..) */

udp_echo_init();

netif->flags |= NETIF_FLAG_IGMP;

igmp_result = igmp_start( netif );

igmp_result = igmp_joingroup( &ipaddr, &ipgroup );

/* receive and process packets */

while (1) {

xemacif_input(netif);

//transfer_data();

}

/* never reached */

cleanup_platform();

return 0;

}

Also, xemac_add calls netif_add, and within which there is the following code:

  netif->flags = 0;

// ...

#if LWIP_IGMP

  /* start IGMP processing */

  if (netif->flags & NETIF_FLAG_IGMP) {

    igmp_start( netif);

  }

#endif /* LWIP_IGMP */

How does igmp_start ever get called? I don't see any code in the file (where I write //... above) that could reset the flag to include NETIF_FLAG_IGMP.

Thanks!

Jonathan