[lwip-users] Re: [lwip] ARP requests from LwIP side

[leon . woestenberg]

Hello,

I'm not sure what lwIP release your are using, but I've recently
submitted 2 bugfixes for both arp.c from lwIP 0.5.0. Search for
the "LW" here:

#define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen =
HTONS(ARPH_PROTOLEN(hdr) | ((len) << 8))
//#define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = HTONS((len)
| (ARPH_PROTOLEN(hdr) << 8)) // LW: bug
#define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = HTONS((len) |
(ARPH_HWLEN(hdr) << 8))


struct pbuf *
arp_query(struct netif *netif, struct eth_addr *ethaddr, struct ip_addr
*ipaddr)
{
  struct arp_hdr *hdr;
  struct pbuf *p;
  u8_t i;

  p = pbuf_alloc(PBUF_LINK, sizeof(struct arp_hdr), PBUF_RAM);
  if(p == NULL) {
    return NULL;
  }

  hdr = p->payload;

  hdr->opcode = htons(ARP_REQUEST);

  for(i = 0; i < 6; ++i) {
    hdr->dhwaddr.addr[i] = 0x00; // LW: bug in lwIP, uses u16_t, but also
0xff instead of 0xffff
    hdr->shwaddr.addr[i] = ethaddr->addr[i];
  }

  ip_addr_set(&(hdr->dipaddr), ipaddr);
  ip_addr_set(&(hdr->sipaddr), &(netif->ip_addr));

  hdr->hwtype = htons(HWTYPE_ETHERNET);
  ARPH_HWLEN_SET(hdr, 6);

  hdr->proto = htons(ETHTYPE_IP);
  ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr));

  for(i = 0; i < 6; ++i) {
    hdr->ethhdr.dest.addr[i] = 0xff;
    hdr->ethhdr.src.addr[i] = ethaddr->addr[i];
  }

  hdr->ethhdr.type = htons(ETHTYPE_ARP);

  return p;
}

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