uip-arp.c

這是一個實時嵌入式作業系統 實作了MCS51 ARM等MCU

/****************************************************************************
 * net/uip/uip-arp.c
 * Implementation of the ARP Address Resolution Protocol.
 *
 *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <[e-mail]>
 *
 * Based on uIP which also has a BSD style license:
 *
 *   Author: Adam Dunkels <[e-mail]>
 *   Copyright (c) 2001-2003, Adam Dunkels.
 *   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/* The Address Resolution Protocol ARP is used for mapping between IP
 * addresses and link level addresses such as the Ethernet MAC
 * addresses. ARP uses broadcast queries to ask for the link level
 * address of a known IP address and the host which is configured with
 * the IP address for which the query was meant, will respond with its
 * link level address.
 *
 * Note: This ARP implementation only supports Ethernet.
 */

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#ifdef CONFIG_NET

#include <sys/types.h>
#include <sys/ioctl.h>

#include <string.h>
#include <debug.h>

#include <netinet/in.h>
#include <net/ethernet.h>
#include <net/uip/uip-arch.h>
#include <net/uip/uip-arp.h>

/****************************************************************************
 * Definitions
 ****************************************************************************/

#define ARP_REQUEST 1
#define ARP_REPLY   2

#define ARP_HWTYPE_ETH 1

#define ETHBUF ((struct uip_eth_hdr *)&dev->d_buf[0])
#define ARPBUF ((struct arp_hdr *)&dev->d_buf[UIP_LLH_LEN])
#define IPBUF  ((struct ethip_hdr *)&dev->d_buf[UIP_LLH_LEN])

/****************************************************************************
 * Private Types
 ****************************************************************************/

/* ARP header -- Size 28 bytes */

struct arp_hdr
{
  uint16 ah_hwtype;        /* 16-bit Hardware type (Ethernet=0x001) */
  uint16 ah_protocol;      /* 16-bit Protocoal type (IP=0x0800 */
  uint8  ah_hwlen;         /*  8-bit Hardware address size (6) */
  uint8  ah_protolen;      /*  8-bit Procotol address size (4) */
  uint16 ah_opcode;        /* 16-bit Operation */
  uint8  ah_shwaddr[6];    /* 48-bit Sender hardware address */   
  uint16 ah_sipaddr[2];    /* 32-bit Sender IP adress */
  uint8  ah_dhwaddr[6];    /* 48-bit Target hardware address */
  uint16 ah_dipaddr[2];    /* 32-bit Target IP address */
};

/* IP header -- Size 20 or 24 bytes */

struct ethip_hdr
{
  uint8  eh_vhl;           /*  8-bit Version (4) and header length (5 or 6) */
  uint8  eh_tos;           /*  8-bit Type of service (e.g., 6=TCP) */
  uint8  eh_len[2];        /* 16-bit Total length */
  uint8  eh_ipid[2];       /* 16-bit Identification */
  uint8  eh_ipoffset[2];   /* 16-bit IP flags + fragment offset */
  uint8  eh_ttl;           /*  8-bit Time to Live */
  uint8  eh_proto;         /*  8-bit Protocol */
  uint16 eh_ipchksum;      /* 16-bit Header checksum */
  uint16 eh_srcipaddr[2];  /* 32-bit Source IP address */
  uint16 eh_destipaddr[2]; /* 32-bit Destination IP address */
  uint16 eh_ipoption[2];   /* (optional) */
};

struct arp_entry
{
  in_addr_t         at_ipaddr;
  struct ether_addr at_ethaddr;
  uint8             at_time;
};

/****************************************************************************
 * Private Data
 ****************************************************************************/

static const struct ether_addr broadcast_ethaddr =
  {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}};
static const uint16 broadcast_ipaddr[2] = {0xffff, 0xffff};

static struct arp_entry arp_table[CONFIG_NET_ARPTAB_SIZE];
static uint8 g_arptime;


/****************************************************************************
 * Private Functions
 ****************************************************************************/

#if defined(CONFIG_NET_DUMPARP) && defined(CONFIG_DEBUG)
static void uip_arp_dump(struct arp_hdr *arp)
{
  ndbg("  HW type: %04x Protocol: %04x\n",
       arp->ah_hwtype, arp->ah_protocol);\
  ndbg("  HW len: %02x Proto len: %02x Operation: %04x\n",
        arp->ah_hwlen, arp->ah_protolen, arp->ah_opcode);
  ndbg("  Sender MAC: %02x:%02x:%02x:%02x:%02x:%02x IP: %d.%d.%d.%d\n",
       arp->ah_shwaddr[0], arp->ah_shwaddr[1], arp->ah_shwaddr[2],
       arp->ah_shwaddr[3], arp->ah_shwaddr[4], arp->ah_shwaddr[5],
       arp->ah_sipaddr[0] & 0xff, arp->ah_sipaddr[0] >> 8,
       arp->ah_sipaddr[1] & 0xff, arp->ah_sipaddr[1] >> 8);
  ndbg("  Dest MAC:   %02x:%02x:%02x:%02x:%02x:%02x IP: %d.%d.%d.%d\n",
       arp->ah_dhwaddr[0], arp->ah_dhwaddr[1], arp->ah_dhwaddr[2],
       arp->ah_dhwaddr[3], arp->ah_dhwaddr[4], arp->ah_dhwaddr[5],
       arp->ah_dipaddr[0] & 0xff, arp->ah_dipaddr[0] >> 8,
       arp->ah_dipaddr[1] & 0xff, arp->ah_dipaddr[1] >> 8);
}
#else
# define uip_arp_dump(arp)
#endif

static void uip_arp_update(uint16 *pipaddr, uint8 *ethaddr)
{
  struct arp_entry *tabptr;
  in_addr_t         ipaddr = uip_ip4addr_conv(pipaddr);
  int               i;

  /* Walk through the ARP mapping table and try to find an entry to
   * update. If none is found, the IP -> MAC address mapping is
   * inserted in the ARP table.
   */

  for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
    {
      tabptr = &arp_table[i];

      /* Only check those entries that are actually in use. */

      if (tabptr->at_ipaddr != 0)
        {
          /* Check if the source IP address of the incoming packet matches
           * the IP address in this ARP table entry.
           */

          if (uip_ipaddr_cmp(ipaddr, tabptr->at_ipaddr))
            {
              /* An old entry found, update this and return. */
              memcpy(tabptr->at_ethaddr.ether_addr_octet, ethaddr, ETHER_ADDR_LEN);
              tabptr->at_time = g_arptime;

              return;
            }
        }
    }

  /* If we get here, no existing ARP table entry was found, so we
     create one. */

  /* First, we try to find an unused entry in the ARP table. */

  for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
    {
      tabptr = &arp_table[i];
      if (tabptr->at_ipaddr == 0)
        {
          break;
        }
    }

  /* If no unused entry is found, we try to find the oldest entry and
   * throw it away.
   */

  if (i == CONFIG_NET_ARPTAB_SIZE)
    {
      uint8 tmpage = 0;
      int   j      = 0;
      for (i = 0; i < CONFIG_NET_ARPTAB_SIZE; ++i)
        {
          tabptr = &arp_table[i];
          if (g_arptime - tabptr->at_time > tmpage)
            {
              tmpage = g_arptime - tabptr->at_time;
              j = i;
            }
        }
      i = j;
      tabptr = &arp_table[i];
    }

  /* Now, i is the ARP table entry which we will fill with the new
   * information.
   */

  tabptr->at_ipaddr = ipaddr;
  memcpy(tabptr->at_ethaddr.ether_addr_octet, ethaddr, ETHER_ADDR_LEN);