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-/**
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- * \addtogroup uip
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- * @{
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- */
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-
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-/**
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- * \defgroup uiparp uIP Address Resolution Protocol
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- * @{
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- *
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- * The Address Resolution Protocol ARP is used for mapping between IP
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- * addresses and link level addresses such as the Ethernet MAC
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- * addresses. ARP uses broadcast queries to ask for the link level
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- * address of a known IP address and the host which is configured with
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- * the IP address for which the query was meant, will respond with its
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- * link level address.
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- *
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- * \note This ARP implementation only supports Ethernet.
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- */
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-
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-/**
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- * \file
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- * Implementation of the ARP Address Resolution Protocol.
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- * \author Adam Dunkels <adam@dunkels.com>
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- *
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- */
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-
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-/*
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- * Copyright (c) 2001-2003, Adam Dunkels.
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- * All rights reserved.
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- *
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- * Redistribution and use in source and binary forms, with or without
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- * modification, are permitted provided that the following conditions
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- * are met:
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- * 1. Redistributions of source code must retain the above copyright
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- * notice, this list of conditions and the following disclaimer.
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- * 2. Redistributions in binary form must reproduce the above copyright
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- * notice, this list of conditions and the following disclaimer in the
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- * documentation and/or other materials provided with the distribution.
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- * 3. The name of the author may not be used to endorse or promote
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- * products derived from this software without specific prior
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- * written permission.
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- *
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- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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- * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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- * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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- * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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- * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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- *
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- * This file is part of the uIP TCP/IP stack.
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- *
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- * $Id$
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- *
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- */
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-
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-
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-#include "uip_arp.h"
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-
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-#include <string.h>
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-
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-struct arp_hdr {
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- struct uip_eth_hdr ethhdr;
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- u16_t hwtype;
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- u16_t protocol;
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- u8_t hwlen;
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- u8_t protolen;
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- u16_t opcode;
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- struct uip_eth_addr shwaddr;
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- u16_t sipaddr[2];
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- struct uip_eth_addr dhwaddr;
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- u16_t dipaddr[2];
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-};
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-
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-struct ethip_hdr {
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- struct uip_eth_hdr ethhdr;
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- /* IP header. */
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- u8_t vhl,
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- tos,
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- len[2],
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- ipid[2],
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- ipoffset[2],
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- ttl,
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- proto;
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- u16_t ipchksum;
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- u16_t srcipaddr[2],
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- destipaddr[2];
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-};
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-
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-#define ARP_REQUEST 1
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-#define ARP_REPLY 2
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-
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-#define ARP_HWTYPE_ETH 1
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-
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-struct arp_entry {
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- u16_t ipaddr[2];
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- struct uip_eth_addr ethaddr;
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- u8_t time;
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-};
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-
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-struct uip_eth_addr uip_ethaddr = {{UIP_ETHADDR0,
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- UIP_ETHADDR1,
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- UIP_ETHADDR2,
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- UIP_ETHADDR3,
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- UIP_ETHADDR4,
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- UIP_ETHADDR5}};
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-
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-static struct arp_entry arp_table[UIP_ARPTAB_SIZE];
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-static u16_t ipaddr[2];
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-static u8_t i, c;
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-
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-static u8_t arptime;
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-static u8_t tmpage;
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-
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-#define BUF ((struct arp_hdr *)&uip_buf[0])
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-#define IPBUF ((struct ethip_hdr *)&uip_buf[0])
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-/*-----------------------------------------------------------------------------------*/
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-/**
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- * Initialize the ARP module.
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- *
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- */
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-/*-----------------------------------------------------------------------------------*/
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-void
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-uip_arp_init(void)
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-{
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- for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
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- memset(arp_table[i].ipaddr, 0, 4);
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- }
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-}
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-/*-----------------------------------------------------------------------------------*/
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-/**
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- * Periodic ARP processing function.
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- *
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- * This function performs periodic timer processing in the ARP module
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- * and should be called at regular intervals. The recommended interval
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- * is 10 seconds between the calls.
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- *
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- */
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-/*-----------------------------------------------------------------------------------*/
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-void
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-uip_arp_timer(void)
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-{
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- struct arp_entry *tabptr;
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-
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- ++arptime;
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- for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
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- tabptr = &arp_table[i];
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- if((tabptr->ipaddr[0] | tabptr->ipaddr[1]) != 0 &&
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- arptime - tabptr->time >= UIP_ARP_MAXAGE) {
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- memset(tabptr->ipaddr, 0, 4);
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- }
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- }
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-
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-}
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-/*-----------------------------------------------------------------------------------*/
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-static void
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-uip_arp_update(u16_t *ipaddr, struct uip_eth_addr *ethaddr)
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-{
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- register struct arp_entry *tabptr;
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- /* Walk through the ARP mapping table and try to find an entry to
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- update. If none is found, the IP -> MAC address mapping is
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- inserted in the ARP table. */
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- for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
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-
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- tabptr = &arp_table[i];
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- /* Only check those entries that are actually in use. */
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- if(tabptr->ipaddr[0] != 0 &&
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- tabptr->ipaddr[1] != 0) {
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-
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- /* Check if the source IP address of the incoming packet matches
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- the IP address in this ARP table entry. */
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- if(ipaddr[0] == tabptr->ipaddr[0] &&
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- ipaddr[1] == tabptr->ipaddr[1]) {
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-
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- /* An old entry found, update this and return. */
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- memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6);
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- tabptr->time = arptime;
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-
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- return;
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- }
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- }
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- }
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-
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- /* If we get here, no existing ARP table entry was found, so we
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- create one. */
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-
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- /* First, we try to find an unused entry in the ARP table. */
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- for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
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- tabptr = &arp_table[i];
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- if(tabptr->ipaddr[0] == 0 &&
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- tabptr->ipaddr[1] == 0) {
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- break;
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- }
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- }
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-
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- /* If no unused entry is found, we try to find the oldest entry and
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- throw it away. */
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- if(i == UIP_ARPTAB_SIZE) {
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- tmpage = 0;
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- c = 0;
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- for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
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- tabptr = &arp_table[i];
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- if(arptime - tabptr->time > tmpage) {
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- tmpage = arptime - tabptr->time;
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- c = i;
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- }
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- }
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- i = c;
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- }
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-
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- /* Now, i is the ARP table entry which we will fill with the new
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- information. */
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- memcpy(tabptr->ipaddr, ipaddr, 4);
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- memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6);
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- tabptr->time = arptime;
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-}
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-/*-----------------------------------------------------------------------------------*/
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-/**
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- * ARP processing for incoming IP packets
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- *
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- * This function should be called by the device driver when an IP
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- * packet has been received. The function will check if the address is
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- * in the ARP cache, and if so the ARP cache entry will be
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- * refreshed. If no ARP cache entry was found, a new one is created.
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- *
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- * This function expects an IP packet with a prepended Ethernet header
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- * in the uip_buf[] buffer, and the length of the packet in the global
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- * variable uip_len.
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- */
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-/*-----------------------------------------------------------------------------------*/
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-void
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-uip_arp_ipin(void)
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-{
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- uip_len -= sizeof(struct uip_eth_hdr);
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-
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- /* Only insert/update an entry if the source IP address of the
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- incoming IP packet comes from a host on the local network. */
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- if((IPBUF->srcipaddr[0] & uip_arp_netmask[0]) !=
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- (uip_hostaddr[0] & uip_arp_netmask[0])) {
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- return;
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- }
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- if((IPBUF->srcipaddr[1] & uip_arp_netmask[1]) !=
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- (uip_hostaddr[1] & uip_arp_netmask[1])) {
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- return;
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- }
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- uip_arp_update(IPBUF->srcipaddr, &(IPBUF->ethhdr.src));
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-
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- return;
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-}
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-/*-----------------------------------------------------------------------------------*/
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-/**
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- * ARP processing for incoming ARP packets.
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- *
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- * This function should be called by the device driver when an ARP
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- * packet has been received. The function will act differently
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- * depending on the ARP packet type: if it is a reply for a request
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- * that we previously sent out, the ARP cache will be filled in with
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- * the values from the ARP reply. If the incoming ARP packet is an ARP
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- * request for our IP address, an ARP reply packet is created and put
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- * into the uip_buf[] buffer.
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- *
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- * When the function returns, the value of the global variable uip_len
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- * indicates whether the device driver should send out a packet or
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- * not. If uip_len is zero, no packet should be sent. If uip_len is
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- * non-zero, it contains the length of the outbound packet that is
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- * present in the uip_buf[] buffer.
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- *
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- * This function expects an ARP packet with a prepended Ethernet
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- * header in the uip_buf[] buffer, and the length of the packet in the
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- * global variable uip_len.
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- */
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-/*-----------------------------------------------------------------------------------*/
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-void
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-uip_arp_arpin(void)
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-{
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-
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- if(uip_len < sizeof(struct arp_hdr)) {
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- uip_len = 0;
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- return;
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- }
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-
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- uip_len = 0;
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-
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- switch(BUF->opcode) {
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- case HTONS(ARP_REQUEST):
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- /* ARP request. If it asked for our address, we send out a
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- reply. */
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- if(BUF->dipaddr[0] == uip_hostaddr[0] &&
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- BUF->dipaddr[1] == uip_hostaddr[1]) {
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- /* The reply opcode is 2. */
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- BUF->opcode = HTONS(2);
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-
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- memcpy(BUF->dhwaddr.addr, BUF->shwaddr.addr, 6);
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- memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6);
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- memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
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- memcpy(BUF->ethhdr.dest.addr, BUF->dhwaddr.addr, 6);
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-
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- BUF->dipaddr[0] = BUF->sipaddr[0];
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- BUF->dipaddr[1] = BUF->sipaddr[1];
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- BUF->sipaddr[0] = uip_hostaddr[0];
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- BUF->sipaddr[1] = uip_hostaddr[1];
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-
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- BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP);
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- uip_len = sizeof(struct arp_hdr);
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- }
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- break;
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- case HTONS(ARP_REPLY):
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- /* ARP reply. We insert or update the ARP table if it was meant
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- for us. */
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- if(BUF->dipaddr[0] == uip_hostaddr[0] &&
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- BUF->dipaddr[1] == uip_hostaddr[1]) {
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-
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- uip_arp_update(BUF->sipaddr, &BUF->shwaddr);
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- }
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- break;
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- }
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-
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- return;
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-}
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-/*-----------------------------------------------------------------------------------*/
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-/**
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- * Prepend Ethernet header to an outbound IP packet and see if we need
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- * to send out an ARP request.
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- *
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- * This function should be called before sending out an IP packet. The
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- * function checks the destination IP address of the IP packet to see
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- * what Ethernet MAC address that should be used as a destination MAC
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- * address on the Ethernet.
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- *
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- * If the destination IP address is in the local network (determined
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- * by logical ANDing of netmask and our IP address), the function
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- * checks the ARP cache to see if an entry for the destination IP
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- * address is found. If so, an Ethernet header is prepended and the
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- * function returns. If no ARP cache entry is found for the
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- * destination IP address, the packet in the uip_buf[] is replaced by
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- * an ARP request packet for the IP address. The IP packet is dropped
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- * and it is assumed that they higher level protocols (e.g., TCP)
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- * eventually will retransmit the dropped packet.
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- *
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- * If the destination IP address is not on the local network, the IP
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- * address of the default router is used instead.
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- *
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- * When the function returns, a packet is present in the uip_buf[]
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- * buffer, and the length of the packet is in the global variable
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- * uip_len.
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- */
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-/*-----------------------------------------------------------------------------------*/
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-void
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-uip_arp_out(void)
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-{
|
355
|
|
- struct arp_entry *tabptr;
|
356
|
|
- /* Find the destination IP address in the ARP table and construct
|
357
|
|
- the Ethernet header. If the destination IP addres isn't on the
|
358
|
|
- local network, we use the default router's IP address instead.
|
359
|
|
-
|
360
|
|
- If not ARP table entry is found, we overwrite the original IP
|
361
|
|
- packet with an ARP request for the IP address. */
|
362
|
|
-
|
363
|
|
- /* Check if the destination address is on the local network. */
|
364
|
|
- if((IPBUF->destipaddr[0] & uip_arp_netmask[0]) !=
|
365
|
|
- (uip_hostaddr[0] & uip_arp_netmask[0]) ||
|
366
|
|
- (IPBUF->destipaddr[1] & uip_arp_netmask[1]) !=
|
367
|
|
- (uip_hostaddr[1] & uip_arp_netmask[1])) {
|
368
|
|
- /* Destination address was not on the local network, so we need to
|
369
|
|
- use the default router's IP address instead of the destination
|
370
|
|
- address when determining the MAC address. */
|
371
|
|
- ipaddr[0] = uip_arp_draddr[0];
|
372
|
|
- ipaddr[1] = uip_arp_draddr[1];
|
373
|
|
- } else {
|
374
|
|
- /* Else, we use the destination IP address. */
|
375
|
|
- ipaddr[0] = IPBUF->destipaddr[0];
|
376
|
|
- ipaddr[1] = IPBUF->destipaddr[1];
|
377
|
|
- }
|
378
|
|
-
|
379
|
|
- for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
|
380
|
|
- tabptr = &arp_table[i];
|
381
|
|
- if(ipaddr[0] == tabptr->ipaddr[0] &&
|
382
|
|
- ipaddr[1] == tabptr->ipaddr[1])
|
383
|
|
- break;
|
384
|
|
- }
|
385
|
|
-
|
386
|
|
- if(i == UIP_ARPTAB_SIZE) {
|
387
|
|
- /* The destination address was not in our ARP table, so we
|
388
|
|
- overwrite the IP packet with an ARP request. */
|
389
|
|
-
|
390
|
|
- memset(BUF->ethhdr.dest.addr, 0xff, 6);
|
391
|
|
- memset(BUF->dhwaddr.addr, 0x00, 6);
|
392
|
|
- memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
|
393
|
|
- memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6);
|
394
|
|
-
|
395
|
|
- BUF->dipaddr[0] = ipaddr[0];
|
396
|
|
- BUF->dipaddr[1] = ipaddr[1];
|
397
|
|
- BUF->sipaddr[0] = uip_hostaddr[0];
|
398
|
|
- BUF->sipaddr[1] = uip_hostaddr[1];
|
399
|
|
- BUF->opcode = HTONS(ARP_REQUEST); /* ARP request. */
|
400
|
|
- BUF->hwtype = HTONS(ARP_HWTYPE_ETH);
|
401
|
|
- BUF->protocol = HTONS(UIP_ETHTYPE_IP);
|
402
|
|
- BUF->hwlen = 6;
|
403
|
|
- BUF->protolen = 4;
|
404
|
|
- BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP);
|
405
|
|
-
|
406
|
|
- uip_appdata = &uip_buf[40 + UIP_LLH_LEN];
|
407
|
|
-
|
408
|
|
- uip_len = sizeof(struct arp_hdr);
|
409
|
|
- return;
|
410
|
|
- }
|
411
|
|
-
|
412
|
|
- /* Build an ethernet header. */
|
413
|
|
- memcpy(IPBUF->ethhdr.dest.addr, tabptr->ethaddr.addr, 6);
|
414
|
|
- memcpy(IPBUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
|
415
|
|
-
|
416
|
|
- IPBUF->ethhdr.type = HTONS(UIP_ETHTYPE_IP);
|
417
|
|
-
|
418
|
|
- uip_len += sizeof(struct uip_eth_hdr);
|
419
|
|
-}
|
420
|
|
-/*-----------------------------------------------------------------------------------*/
|
421
|
|
-
|
422
|
|
-/** @} */
|
423
|
|
-/** @} */
|