etharp.c

lwip-1.4.0

  ((arp_table[i].state == ETHARP_STATE_PENDING) ||
   (arp_table[i].state == ETHARP_STATE_STABLE)));

  /* do we have a pending entry? or an implicit query request? */
  if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
    /* try to resolve it; send out ARP request */
    result = etharp_request(netif, ipaddr);
    if (result != ERR_OK) {
      /* ARP request couldn't be sent */
      /* We don't re-send arp request in etharp_tmr, but we still queue packets,
         since this failure could be temporary, and the next packet calling
         etharp_query again could lead to sending the queued packets. */
    }
    if (q == NULL) {
      return result;
    }
  }

  /* packet given? */
  LWIP_ASSERT("q != NULL", q != NULL);
  /* stable entry? */
  if (arp_table[i].state == ETHARP_STATE_STABLE) {
    /* we have a valid IP->Ethernet address mapping */
    ETHARP_SET_HINT(netif, i);
    /* send the packet */
    result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
  /* pending entry? (either just created or already pending */
  } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
    /* entry is still pending, queue the given packet 'q' */
    struct pbuf *p;
    int copy_needed = 0;
    /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
     * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
     * PBUF_ROMs can be left as they are, since ROM must not get changed. */
    p = q;
    while (p) {
      LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
      if(p->type != PBUF_ROM) {
        copy_needed = 1;
        break;
      }
      p = p->next;
    }
    if(copy_needed) {
      /* copy the whole packet into new pbufs */
      p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
      if(p != NULL) {
        if (pbuf_copy(p, q) != ERR_OK) {
          pbuf_free(p);
          p = NULL;
        }
      }
    } else {
      /* referencing the old pbuf is enough */
      p = q;
      pbuf_ref(p);
    }
    /* packet could be taken over? */
    if (p != NULL) {
      /* queue packet ... */
#if ARP_QUEUEING
      struct etharp_q_entry *new_entry;
      /* allocate a new arp queue entry */
      new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
      if (new_entry != NULL) {
        new_entry->next = 0;
        new_entry->p = p;
        if(arp_table[i].q != NULL) {
          /* queue was already existent, append the new entry to the end */
          struct etharp_q_entry *r;
          r = arp_table[i].q;
          while (r->next != NULL) {
            r = r->next;
          }
          r->next = new_entry;
        } else {
          /* queue did not exist, first item in queue */
          arp_table[i].q = new_entry;
        }
        LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
        result = ERR_OK;
      } else {
        /* the pool MEMP_ARP_QUEUE is empty */
        pbuf_free(p);
        LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
        result = ERR_MEM;
      }
#else /* ARP_QUEUEING */
      /* always queue one packet per ARP request only, freeing a previously queued packet */
      if (arp_table[i].q != NULL) {
        LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: dropped previously queued packet %p for ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
        pbuf_free(arp_table[i].q);
      }
      arp_table[i].q = p;
      result = ERR_OK;
      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
#endif /* ARP_QUEUEING */
    } else {
      ETHARP_STATS_INC(etharp.memerr);
      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
      result = ERR_MEM;
    }
  }
  return result;
}

/**
 * Send a raw ARP packet (opcode and all addresses can be modified)
 *
 * @param netif the lwip network interface on which to send the ARP packet
 * @param ethsrc_addr the source MAC address for the ethernet header
 * @param ethdst_addr the destination MAC address for the ethernet header
 * @param hwsrc_addr the source MAC address for the ARP protocol header
 * @param ipsrc_addr the source IP address for the ARP protocol header
 * @param hwdst_addr the destination MAC address for the ARP protocol header
 * @param ipdst_addr the destination IP address for the ARP protocol header
 * @param opcode the type of the ARP packet
 * @return ERR_OK if the ARP packet has been sent
 *         ERR_MEM if the ARP packet couldn't be allocated
 *         any other err_t on failure
 */
#if !LWIP_AUTOIP
static
#endif /* LWIP_AUTOIP */
err_t
etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
           const struct eth_addr *ethdst_addr,
           const struct eth_addr *hwsrc_addr, const ip_addr_t *ipsrc_addr,
           const struct eth_addr *hwdst_addr, const ip_addr_t *ipdst_addr,
           const u16_t opcode)
{
  struct pbuf *p;
  err_t result = ERR_OK;
  struct eth_hdr *ethhdr;
  struct etharp_hdr *hdr;
#if LWIP_AUTOIP
  const u8_t * ethdst_hwaddr;
#endif /* LWIP_AUTOIP */

  /* allocate a pbuf for the outgoing ARP request packet */
  p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
  /* could allocate a pbuf for an ARP request? */
  if (p == NULL) {
    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
      ("etharp_raw: could not allocate pbuf for ARP request.\n"));
    ETHARP_STATS_INC(etharp.memerr);
    return ERR_MEM;
  }
  LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
              (p->len >= SIZEOF_ETHARP_PACKET));

  ethhdr = (struct eth_hdr *)p->payload;
  hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
  hdr->opcode = htons(opcode);

  LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
              (netif->hwaddr_len == ETHARP_HWADDR_LEN));
#if LWIP_AUTOIP
  /* If we are using Link-Local, all ARP packets that contain a Link-Local
   * 'sender IP address' MUST be sent using link-layer broadcast instead of
   * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
  ethdst_hwaddr = ip_addr_islinklocal(ipsrc_addr) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
#endif /* LWIP_AUTOIP */
  /* Write the ARP MAC-Addresses */
  ETHADDR16_COPY(&hdr->shwaddr, hwsrc_addr);
  ETHADDR16_COPY(&hdr->dhwaddr, hwdst_addr);
  /* Write the Ethernet MAC-Addresses */
#if LWIP_AUTOIP
  ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
#else  /* LWIP_AUTOIP */
  ETHADDR16_COPY(&ethhdr->dest, ethdst_addr);
#endif /* LWIP_AUTOIP */
  ETHADDR16_COPY(&ethhdr->src, ethsrc_addr);
  /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
   * structure packing. */ 
  IPADDR2_COPY(&hdr->sipaddr, ipsrc_addr);
  IPADDR2_COPY(&hdr->dipaddr, ipdst_addr);

  hdr->hwtype = PP_HTONS(HWTYPE_ETHERNET);
  hdr->proto = PP_HTONS(ETHTYPE_IP);
  /* set hwlen and protolen */
  hdr->hwlen = ETHARP_HWADDR_LEN;
  hdr->protolen = sizeof(ip_addr_t);

  ethhdr->type = PP_HTONS(ETHTYPE_ARP);
  /* send ARP query */
  result = netif->linkoutput(netif, p);
  ETHARP_STATS_INC(etharp.xmit);
  /* free ARP query packet */
  pbuf_free(p);
  p = NULL;
  /* could not allocate pbuf for ARP request */

  return result;
}

/**
 * Send an ARP request packet asking for ipaddr.
 *
 * @param netif the lwip network interface on which to send the request
 * @param ipaddr the IP address for which to ask
 * @return ERR_OK if the request has been sent
 *         ERR_MEM if the ARP packet couldn't be allocated
 *         any other err_t on failure
 */
err_t
etharp_request(struct netif *netif, ip_addr_t *ipaddr)
{
  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
  return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
                    (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
                    ipaddr, ARP_REQUEST);
}
#endif /* LWIP_ARP */

/**
 * Process received ethernet frames. Using this function instead of directly
 * calling ip_input and passing ARP frames through etharp in ethernetif_input,
 * the ARP cache is protected from concurrent access.
 *
 * @param p the recevied packet, p->payload pointing to the ethernet header
 * @param netif the network interface on which the packet was received
 */
err_t
ethernet_input(struct pbuf *p, struct netif *netif)
{
  struct eth_hdr* ethhdr;
  u16_t type;
  s16_t ip_hdr_offset = SIZEOF_ETH_HDR;

  if (p->len <= SIZEOF_ETH_HDR) {
    /* a packet with only an ethernet header (or less) is not valid for us */
    ETHARP_STATS_INC(etharp.proterr);
    ETHARP_STATS_INC(etharp.drop);
    goto free_and_return;
  }

  /* points to packet payload, which starts with an Ethernet header */
  ethhdr = (struct eth_hdr *)p->payload;
  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
    ("ethernet_input: dest:%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F", src:%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F", type:%"X16_F"\n",
     (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
     (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
     (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
     (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
     (unsigned)htons(ethhdr->type)));

  type = ethhdr->type;
#if ETHARP_SUPPORT_VLAN
  if (type == PP_HTONS(ETHTYPE_VLAN)) {
    struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
    if (p->len <= SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR) {
      /* a packet with only an ethernet/vlan header (or less) is not valid for us */
      ETHARP_STATS_INC(etharp.proterr);
      ETHARP_STATS_INC(etharp.drop);
      goto free_and_return;
    }
#ifdef ETHARP_VLAN_CHECK /* if not, allow all VLANs */
    if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
      /* silently ignore this packet: not for our VLAN */
      pbuf_free(p);
      return ERR_OK;
    }
#endif /* ETHARP_VLAN_CHECK */
    type = vlan->tpid;
    ip_hdr_offset = SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR;
  }
#endif /* ETHARP_SUPPORT_VLAN */

#if LWIP_ARP_FILTER_NETIF
  netif = LWIP_ARP_FILTER_NETIF_FN(p, netif, htons(type));
#endif /* LWIP_ARP_FILTER_NETIF*/

  switch (type) {
#if LWIP_ARP
    /* IP packet? */
    case PP_HTONS(ETHTYPE_IP):
      if (!(netif->flags & NETIF_FLAG_ETHARP)) {
        goto free_and_return;
      }
#if ETHARP_TRUST_IP_MAC
      /* update ARP table */
      etharp_ip_input(netif, p);
#endif /* ETHARP_TRUST_IP_MAC */
      /* skip Ethernet header */
      if(pbuf_header(p, -ip_hdr_offset)) {
        LWIP_ASSERT("Can't move over header in packet", 0);
        goto free_and_return;
      } else {
        /* pass to IP layer */
        ip_input(p, netif);
      }
      break;
      
    case PP_HTONS(ETHTYPE_ARP):
      if (!(netif->flags & NETIF_FLAG_ETHARP)) {
        goto free_and_return;
      }
      /* pass p to ARP module */
      etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
      break;
#endif /* LWIP_ARP */
#if PPPOE_SUPPORT
    case PP_HTONS(ETHTYPE_PPPOEDISC): /* PPP Over Ethernet Discovery Stage */
      pppoe_disc_input(netif, p);
      break;

    case PP_HTONS(ETHTYPE_PPPOE): /* PPP Over Ethernet Session Stage */
      pppoe_data_input(netif, p);
      break;
#endif /* PPPOE_SUPPORT */

    default:
      ETHARP_STATS_INC(etharp.proterr);
      ETHARP_STATS_INC(etharp.drop);
      goto free_and_return;
  }

  /* This means the pbuf is freed or consumed,
     so the caller doesn't have to free it again */
  return ERR_OK;

free_and_return:
  pbuf_free(p);
  return ERR_OK;
}
#endif /* LWIP_ARP || LWIP_ETHERNET */