uip-input.c

来自「這是一個實時嵌入式作業系統 實作了MCS51 ARM等MCU」· C语言 代码 · 共 526 行 · 第 1/2 页

         * now on.
         */

        BUF->ipoffset[0] = BUF->ipoffset[1] = 0;
        BUF->len[0] = uip_reasslen >> 8;
        BUF->len[1] = uip_reasslen & 0xff;
        BUF->ipchksum = 0;
        BUF->ipchksum = ~(uip_ipchksum(dev));

        return uip_reasslen;
      }
  }

nullreturn:
  return 0;
}
#endif /* UIP_REASSEMBLY */

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Function: uip_input
 *
 * Description:
 *
 * Assumptions:
 *
 ****************************************************************************/

void uip_input(struct uip_driver_s *dev)
{
  /* This is where the input processing starts. */

#ifdef CONFIG_NET_STATISTICS
  uip_stat.ip.recv++;
#endif

  /* Start of IP input header processing code. */

#ifdef CONFIG_NET_IPv6
  /* Check validity of the IP header. */

  if ((BUF->vtc & 0xf0) != 0x60) 
    {
      /* IP version and header length. */

#ifdef CONFIG_NET_STATISTICS
      uip_stat.ip.drop++;
      uip_stat.ip.vhlerr++;
#endif
      ndbg("Invalid IPv6 version: %d\n", BUF->vtc >> 4);
      goto drop;
    }
#else /* CONFIG_NET_IPv6 */
  /* Check validity of the IP header. */

  if (BUF->vhl != 0x45)
    {
      /* IP version and header length. */

#ifdef CONFIG_NET_STATISTICS
      uip_stat.ip.drop++;
      uip_stat.ip.vhlerr++;
#endif
      ndbg("Invalid IP version or header length: %02x\n", BUF->vhl);
      goto drop;
    }
#endif /* CONFIG_NET_IPv6 */

  /* Check the size of the packet. If the size reported to us in d_len is
   * smaller the size reported in the IP header, we assume that the packet
   * has been corrupted in transit. If the size of d_len is larger than the
   * size reported in the IP packet header, the packet has been padded and
   * we set d_len to the correct value.
   */

  if ((BUF->len[0] << 8) + BUF->len[1] <= dev->d_len)
    {
      dev->d_len = (BUF->len[0] << 8) + BUF->len[1];
#ifdef CONFIG_NET_IPv6
      /* The length reported in the IPv6 header is the length of the
       * payload that follows the header. However, uIP uses the d_len
       * variable for holding the size of the entire packet, including the
       * IP header. For IPv4 this is not a problem as the length field in
       * the IPv4 header contains the length of the entire packet. But
       * for IPv6 we need to add the size of the IPv6 header (40 bytes).
       */

      dev->d_len += 40;
#endif /* CONFIG_NET_IPv6 */
    }
  else
    {
      ndbg("IP packet shorter than length in IP header\n");
      goto drop;
    }

#ifndef CONFIG_NET_IPv6
  /* Check the fragment flag. */

  if ((BUF->ipoffset[0] & 0x3f) != 0 || BUF->ipoffset[1] != 0)
    {
#if UIP_REASSEMBLY
      dev->d_len = uip_reass();
      if (dev->d_len == 0)
        {
          goto drop;
        }
#else /* UIP_REASSEMBLY */
#ifdef CONFIG_NET_STATISTICS
      uip_stat.ip.drop++;
      uip_stat.ip.fragerr++;
#endif
      ndbg("IP fragment dropped\n");
      goto drop;
#endif /* UIP_REASSEMBLY */
    }
#endif /* CONFIG_NET_IPv6 */

   /* If IP broadcast support is configured, we check for a broadcast
    * UDP packet, which may be destined to us (even if there is no IP
    * address yet assigned to the device as is the case when we are
    * negotiating over DHCP for an address).
    */

#if defined(CONFIG_NET_BROADCAST) && defined(CONFIG_NET_UDP)
  if (BUF->proto == UIP_PROTO_UDP &&
#ifndef CONFIG_NET_IPv6
      uip_ipaddr_cmp(uip_ip4addr_conv(BUF->destipaddr), g_alloneaddr))
#else
      uip_ipaddr_cmp(BUF->destipaddr, g_alloneaddr))
#endif
    {
      uip_udpinput(dev);
      return;
    }

  /* In most other cases, the device must be assigned a non-zero IP
   * address.  Another exception is when CONFIG_NET_PINGADDRCONF is
   * enabled...
   */

  else
#endif
  if (uip_ipaddr_cmp(dev->d_ipaddr, g_allzeroaddr))
    {
      /* If we are configured to use ping IP address configuration and
       * hasn't been assigned an IP address yet, we accept all ICMP
       * packets.
       */

#if defined(CONFIG_NET_PINGADDRCONF) && !defined(CONFIG_NET_IPv6)
      if (BUF->proto == UIP_PROTO_ICMP)
        {
          ndbg("Possible ping config packet received\n");
          uip_icmpinput(dev);
          goto done;
        }
      else
#endif
        {
          ndbg("No IP address assigned\n");
          goto drop;
        }
    }

  /* Check if the pack is destined for out IP address */
  else
    {
      /* Check if the packet is destined for our IP address. */
#ifndef CONFIG_NET_IPv6
      if (!uip_ipaddr_cmp(uip_ip4addr_conv(BUF->destipaddr), dev->d_ipaddr))
        {
#ifdef CONFIG_NET_STATISTICS
          uip_stat.ip.drop++;
#endif
          goto drop;
        }
#else /* CONFIG_NET_IPv6 */
      /* For IPv6, packet reception is a little trickier as we need to
       * make sure that we listen to certain multicast addresses (all
       * hosts multicast address, and the solicited-node multicast
       * address) as well. However, we will cheat here and accept all
       * multicast packets that are sent to the ff02::/16 addresses.
       */

      if (!uip_ipaddr_cmp(BUF->destipaddr, dev->d_ipaddr) &&
           BUF->destipaddr & HTONL(0xffff0000) != HTONL(0xff020000))
        {
#ifdef CONFIG_NET_STATISTICS
          uip_stat.ip.drop++;
#endif
          goto drop;
        }
#endif /* CONFIG_NET_IPv6 */
    }

#ifndef CONFIG_NET_IPv6
  if (uip_ipchksum(dev) != 0xffff)
    {
      /* Compute and check the IP header checksum. */

#ifdef CONFIG_NET_STATISTICS
      uip_stat.ip.drop++;
      uip_stat.ip.chkerr++;
#endif
      ndbg("Bad IP checksum\n");
      goto drop;
    }
#endif /* CONFIG_NET_IPv6 */

  /* Everything looks good so far.  Now process the incoming packet
   * according to the protocol.
   */

  switch (BUF->proto)
    {
#ifdef CONFIG_NET_TCP
      case UIP_PROTO_TCP:   /* TCP input */
        uip_tcpinput(dev);
        break;
#endif

#ifdef CONFIG_NET_UDP
      case UIP_PROTO_UDP:   /* UDP input */
        uip_udpinput(dev);
        break;
#endif

  /* Check for ICMP input */

#ifdef CONFIG_NET_ICMP
#ifndef CONFIG_NET_IPv6
      case UIP_PROTO_ICMP:  /* ICMP input */
#else
      case UIP_PROTO_ICMP6: /* ICMP6 input */
#endif
        uip_icmpinput(dev);
        break;
#endif

      default:              /* Unrecognized/unsupported protocol */
#ifdef CONFIG_NET_STATISTICS
        uip_stat.ip.drop++;
        uip_stat.ip.protoerr++;
#endif

        ndbg("Unrecognized IP protocol\n");
        goto drop;
    }

  /* Return and let the caller do any actual transmission. */

  return;

drop:
  dev->d_len = 0;
}
#endif /* CONFIG_NET */