433 lines
14 KiB
C
433 lines
14 KiB
C
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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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* \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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* \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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* 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: uip_arp.c,v 1.5 2008/02/07 01:35:00 adamdunkels Exp $
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*
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*/
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#include "uip_arp.h"
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#include <string.h>
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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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uip_ipaddr_t sipaddr;
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struct uip_eth_addr dhwaddr;
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uip_ipaddr_t dipaddr;
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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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uip_ipaddr_t srcipaddr, destipaddr;
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};
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#define ARP_REQUEST 1
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#define ARP_REPLY 2
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#define ARP_HWTYPE_ETH 1
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struct arp_entry {
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uip_ipaddr_t ipaddr;
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struct uip_eth_addr ethaddr;
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u8_t time;
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};
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static const struct uip_eth_addr broadcast_ethaddr =
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{{0xff,0xff,0xff,0xff,0xff,0xff}};
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static const u16_t broadcast_ipaddr[2] = {0xffff,0xffff};
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static struct arp_entry arp_table[UIP_ARPTAB_SIZE];
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static uip_ipaddr_t ipaddr;
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static u8_t i, c;
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static u8_t arptime;
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static u8_t tmpage;
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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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#define DEBUG 0
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#if DEBUG
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#include <stdio.h>
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#define PRINTF(...) printf(__VA_ARGS__)
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#else
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#define PRINTF(...)
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#endif
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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 = NULL;
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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(uip_ipaddr_cmp(&tabptr->ipaddr, &uip_all_zeroes_addr) &&
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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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static void
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uip_arp_update(uip_ipaddr_t *ipaddr, struct uip_eth_addr *ethaddr)
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{
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register struct arp_entry *tabptr = NULL;
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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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tabptr = &arp_table[i];
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/* Only check those entries that are actually in use. */
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if(!uip_ipaddr_cmp(&tabptr->ipaddr, &uip_all_zeroes_addr)) {
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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(uip_ipaddr_cmp(ipaddr, &tabptr->ipaddr)) {
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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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return;
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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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/* 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(uip_ipaddr_cmp(&tabptr->ipaddr, &uip_all_zeroes_addr)) {
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break;
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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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tabptr = &arp_table[i];
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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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uip_ipaddr_copy(&tabptr->ipaddr, ipaddr);
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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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#if 0
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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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/* 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_netmask[0]) !=
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(uip_hostaddr[0] & uip_netmask[0])) {
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return;
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}
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if((IPBUF->srcipaddr[1] & uip_netmask[1]) !=
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(uip_hostaddr[1] & uip_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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return;
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}
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#endif /* 0 */
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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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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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uip_len = 0;
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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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PRINTF("uip_arp_arpin: request for %d.%d.%d.%d (we are %d.%d.%d.%d)\n",
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BUF->dipaddr.u8[0], BUF->dipaddr.u8[1],
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BUF->dipaddr.u8[2], BUF->dipaddr.u8[3],
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uip_hostaddr.u8[0], uip_hostaddr.u8[1],
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uip_hostaddr.u8[2], uip_hostaddr.u8[3]);
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if(uip_ipaddr_cmp(&BUF->dipaddr, &uip_hostaddr)) {
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/* First, we register the one who made the request in our ARP
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table, since it is likely that we will do more communication
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with this host in the future. */
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uip_arp_update(&BUF->sipaddr, &BUF->shwaddr);
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BUF->opcode = HTONS(ARP_REPLY);
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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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uip_ipaddr_copy(&BUF->dipaddr, &BUF->sipaddr);
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uip_ipaddr_copy(&BUF->sipaddr, &uip_hostaddr);
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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(uip_ipaddr_cmp(&BUF->dipaddr, &uip_hostaddr)) {
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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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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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{
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struct arp_entry *tabptr = NULL;
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/* Find the destination IP address in the ARP table and construct
|
||
|
|
the Ethernet header. If the destination IP address isn't on the
|
||
|
|
local network, we use the default router's IP address instead.
|
||
|
|
|
||
|
|
If not ARP table entry is found, we overwrite the original IP
|
||
|
|
packet with an ARP request for the IP address. */
|
||
|
|
|
||
|
|
/* First check if destination is a local broadcast. */
|
||
|
|
if(uip_ipaddr_cmp(&IPBUF->destipaddr, &uip_broadcast_addr)) {
|
||
|
|
memcpy(IPBUF->ethhdr.dest.addr, broadcast_ethaddr.addr, 6);
|
||
|
|
} else {
|
||
|
|
/* Check if the destination address is on the local network. */
|
||
|
|
if(!uip_ipaddr_maskcmp(&IPBUF->destipaddr, &uip_hostaddr, &uip_netmask)) {
|
||
|
|
/* Destination address was not on the local network, so we need to
|
||
|
|
use the default router's IP address instead of the destination
|
||
|
|
address when determining the MAC address. */
|
||
|
|
uip_ipaddr_copy(&ipaddr, &uip_draddr);
|
||
|
|
} else {
|
||
|
|
/* Else, we use the destination IP address. */
|
||
|
|
uip_ipaddr_copy(&ipaddr, &IPBUF->destipaddr);
|
||
|
|
}
|
||
|
|
|
||
|
|
for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
|
||
|
|
tabptr = &arp_table[i];
|
||
|
|
if(uip_ipaddr_cmp(&ipaddr, &tabptr->ipaddr)) {
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if(i == UIP_ARPTAB_SIZE) {
|
||
|
|
/* The destination address was not in our ARP table, so we
|
||
|
|
overwrite the IP packet with an ARP request. */
|
||
|
|
|
||
|
|
memset(BUF->ethhdr.dest.addr, 0xff, 6);
|
||
|
|
memset(BUF->dhwaddr.addr, 0x00, 6);
|
||
|
|
memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
|
||
|
|
memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6);
|
||
|
|
|
||
|
|
uip_ipaddr_copy(&BUF->dipaddr, &ipaddr);
|
||
|
|
uip_ipaddr_copy(&BUF->sipaddr, &uip_hostaddr);
|
||
|
|
BUF->opcode = HTONS(ARP_REQUEST); /* ARP request. */
|
||
|
|
BUF->hwtype = HTONS(ARP_HWTYPE_ETH);
|
||
|
|
BUF->protocol = HTONS(UIP_ETHTYPE_IP);
|
||
|
|
BUF->hwlen = 6;
|
||
|
|
BUF->protolen = 4;
|
||
|
|
BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP);
|
||
|
|
|
||
|
|
uip_appdata = &uip_buf[UIP_TCPIP_HLEN + UIP_LLH_LEN];
|
||
|
|
|
||
|
|
uip_len = sizeof(struct arp_hdr);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Build an ethernet header. */
|
||
|
|
memcpy(IPBUF->ethhdr.dest.addr, tabptr->ethaddr.addr, 6);
|
||
|
|
}
|
||
|
|
memcpy(IPBUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
|
||
|
|
|
||
|
|
IPBUF->ethhdr.type = HTONS(UIP_ETHTYPE_IP);
|
||
|
|
|
||
|
|
uip_len += sizeof(struct uip_eth_hdr);
|
||
|
|
}
|
||
|
|
/*-----------------------------------------------------------------------------------*/
|
||
|
|
|
||
|
|
/** @} */
|
||
|
|
/** @} */
|
||
|
|
|