Re: [lwip-users] Using ARP to get MAC address

[Tomas Daujotas]

A small update:

In etharp_find_addr(), I've found that I don't get
ETHARP_STATE_STABLE, but the index returned is correct here:

s8_t etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr, struct
eth_addr **eth_ret, ip_addr_t **ip_ret) {

  s8_t i;

  LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL", eth_ret != NULL &&
ip_ret != NULL);

  LWIP_UNUSED_ARG(netif);

  i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY); // <<--- here returns
table index 0

  if((i >= 0) && arp_table[i].state == 1) {     //ETHARP_STATE_STABLE)
{ <<--- I don't know what flag is equal to ETHARP_STATE_STABLE, so
let's override it for tests only
      *eth_ret = &arp_table[i].ethaddr; // <<--- returned all 0
      *ip_ret = &arp_table[i].ipaddr; // returned correct IP address
      return i; // returns 0
  }
  return -1;
}

I get the index 0, so I've overrided the ETHARP_STATE_STABLE part,
since arp_table[i].state returns 1.

Now the check part:

I've defined required structs as pointers:

struct ip_addr * ret_ip_addr;
struct eth_addr * ret_eth_addr;

Then the check part is:

        arp_query = etharp_query(&alteraTseNetif, &alteraTseNetif.gw, NULL);
        arp_find = etharp_find_addr(&alteraTseNetif, &alteraTseNetif.gw,
&ret_eth_addr, &ret_ip_addr);

    if(arp_query != ERR_OK) {
        printf("Query FAIL (returned: %d)\n",arp_query);
    } else {
        printf("Query OK, trying to find MAC address...\n");
                if(arp_find > -1) {
                        printf("Find addr OK (returned arp table index number:
%d)\n", arp_find);
                        printf("Returned IP: 0x%08X\n", (unsigned 
int)ret_ip_addr->addr);
                        printf("Returned MAC: %02X:%02X:%02X:%02X:%02X:%02X\n",
ret_eth_addr->addr[0],
                                                                                
                                                        ret_eth_addr->addr[1],
                                                                                
                                                        ret_eth_addr->addr[2],
                                                                                
                                                        ret_eth_addr->addr[3],
                                                                                
                                                        ret_eth_addr->addr[4],
                                                                                
                                                        ret_eth_addr->addr[5]);
                } else {
                        printf("Find addr FAIL (returned %d)\n", arp_find);
                }
    }

I get the correct result in ret_ip_addr pointer, which, as You can
see, returns my gateway address (same as alteraTseNetif.gw). However
my MAC pointer returns all six 0x00. This means the table isn't
updated?