893 lines
32 KiB
C
893 lines
32 KiB
C
/**
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* @file
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* Address Resolution Protocol module for IP over Ethernet
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*
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* Functionally, ARP is divided into two parts. The first maps an IP address
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* to a physical address when sending a packet, and the second part answers
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* requests from other machines for our physical address.
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*
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* This implementation complies with RFC 826 (Ethernet ARP). It supports
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* Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6
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* if an interface calls etharp_query(our_netif, its_ip_addr, NULL) upon
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* address change.
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*/
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/*
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* Copyright (c) 2001-2003 Swedish Institute of Computer Science.
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* Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv>
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* Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands.
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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 modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* 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 products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* This file is part of the lwIP TCP/IP stack.
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*
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*/
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#include <string.h>
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#include "lwip/opt.h"
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#include "lwip/inet.h"
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#include "netif/etharp.h"
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#include "lwip/ip.h"
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#include "lwip/stats.h"
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#include "lwip/snmp.h"
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/* ARP needs to inform DHCP of any ARP replies? */
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#if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
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# include "lwip/dhcp.h"
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#endif
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/** the time an ARP entry stays valid after its last update,
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* (240 * 5) seconds = 20 minutes.
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*/
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#define ARP_MAXAGE 240
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/** the time an ARP entry stays pending after first request,
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* (2 * 5) seconds = 10 seconds.
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*
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* @internal Keep this number at least 2, otherwise it might
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* run out instantly if the timeout occurs directly after a request.
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*/
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#define ARP_MAXPENDING 2
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#define HWTYPE_ETHERNET 1
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/** ARP message types */
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#define ARP_REQUEST 1
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#define ARP_REPLY 2
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#define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8)
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#define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff)
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#define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8))
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#define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8))
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enum etharp_state {
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ETHARP_STATE_EMPTY,
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ETHARP_STATE_PENDING,
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ETHARP_STATE_STABLE,
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/** @internal transitional state used in etharp_tmr() for convenience*/
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ETHARP_STATE_EXPIRED
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};
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struct etharp_entry {
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#if ARP_QUEUEING
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/**
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* Pointer to queue of pending outgoing packets on this ARP entry.
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*/
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struct pbuf *p;
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#endif
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struct ip_addr ipaddr;
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struct eth_addr ethaddr;
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enum etharp_state state;
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u8_t ctime;
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struct netif *netif;
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};
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static const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
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static struct etharp_entry arp_table[ARP_TABLE_SIZE];
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/**
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* Try hard to create a new entry - we want the IP address to appear in
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* the cache (even if this means removing an active entry or so). */
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#define ETHARP_TRY_HARD 1
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static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags);
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static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags);
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/**
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* Initializes ARP module.
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*/
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void
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etharp_init(void)
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{
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u8_t i;
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/* clear ARP entries */
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for(i = 0; i < ARP_TABLE_SIZE; ++i) {
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arp_table[i].state = ETHARP_STATE_EMPTY;
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#if ARP_QUEUEING
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arp_table[i].p = NULL;
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#endif
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arp_table[i].ctime = 0;
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arp_table[i].netif = NULL;
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}
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}
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/**
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* Clears expired entries in the ARP table.
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*
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* This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
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* in order to expire entries in the ARP table.
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*/
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void
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etharp_tmr(void)
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{
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u8_t i;
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LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
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/* remove expired entries from the ARP table */
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for (i = 0; i < ARP_TABLE_SIZE; ++i) {
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arp_table[i].ctime++;
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/* stable entry? */
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if ((arp_table[i].state == ETHARP_STATE_STABLE) &&
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/* entry has become old? */
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(arp_table[i].ctime >= ARP_MAXAGE)) {
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LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired stable entry %"U16_F".\n", (u16_t)i));
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arp_table[i].state = ETHARP_STATE_EXPIRED;
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/* pending entry? */
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} else if (arp_table[i].state == ETHARP_STATE_PENDING) {
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/* entry unresolved/pending for too long? */
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if (arp_table[i].ctime >= ARP_MAXPENDING) {
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LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired pending entry %"U16_F".\n", (u16_t)i));
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arp_table[i].state = ETHARP_STATE_EXPIRED;
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#if ARP_QUEUEING
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} else if (arp_table[i].p != NULL) {
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/* resend an ARP query here */
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#endif
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}
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}
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/* clean up entries that have just been expired */
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if (arp_table[i].state == ETHARP_STATE_EXPIRED) {
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/* remove from SNMP ARP index tree */
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snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
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#if ARP_QUEUEING
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/* and empty packet queue */
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if (arp_table[i].p != NULL) {
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/* remove all queued packets */
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LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].p)));
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pbuf_free(arp_table[i].p);
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arp_table[i].p = NULL;
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}
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#endif
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/* recycle entry for re-use */
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arp_table[i].state = ETHARP_STATE_EMPTY;
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}
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}
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}
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/**
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* Search the ARP table for a matching or new entry.
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*
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* If an IP address is given, return a pending or stable ARP entry that matches
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* the address. If no match is found, create a new entry with this address set,
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* but in state ETHARP_EMPTY. The caller must check and possibly change the
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* state of the returned entry.
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*
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* If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
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*
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* In all cases, attempt to create new entries from an empty entry. If no
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* empty entries are available and ETHARP_TRY_HARD flag is set, recycle
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* old entries. Heuristic choose the least important entry for recycling.
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*
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* @param ipaddr IP address to find in ARP cache, or to add if not found.
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* @param flags
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* - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of
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* active (stable or pending) entries.
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*
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* @return The ARP entry index that matched or is created, ERR_MEM if no
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* entry is found or could be recycled.
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*/
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static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags)
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{
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s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
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s8_t empty = ARP_TABLE_SIZE;
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u8_t i = 0, age_pending = 0, age_stable = 0;
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#if ARP_QUEUEING
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/* oldest entry with packets on queue */
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s8_t old_queue = ARP_TABLE_SIZE;
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/* its age */
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u8_t age_queue = 0;
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#endif
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/**
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* a) do a search through the cache, remember candidates
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* b) select candidate entry
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* c) create new entry
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*/
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/* a) in a single search sweep, do all of this
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* 1) remember the first empty entry (if any)
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* 2) remember the oldest stable entry (if any)
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* 3) remember the oldest pending entry without queued packets (if any)
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* 4) remember the oldest pending entry with queued packets (if any)
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* 5) search for a matching IP entry, either pending or stable
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* until 5 matches, or all entries are searched for.
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*/
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for (i = 0; i < ARP_TABLE_SIZE; ++i) {
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/* no empty entry found yet and now we do find one? */
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if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) {
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LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
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/* remember first empty entry */
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empty = i;
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}
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/* pending entry? */
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else if (arp_table[i].state == ETHARP_STATE_PENDING) {
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/* if given, does IP address match IP address in ARP entry? */
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if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
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/* found exact IP address match, simply bail out */
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return i;
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#if ARP_QUEUEING
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/* pending with queued packets? */
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} else if (arp_table[i].p != NULL) {
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if (arp_table[i].ctime >= age_queue) {
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old_queue = i;
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age_queue = arp_table[i].ctime;
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}
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#endif
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/* pending without queued packets? */
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} else {
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if (arp_table[i].ctime >= age_pending) {
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old_pending = i;
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age_pending = arp_table[i].ctime;
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}
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}
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}
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/* stable entry? */
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else if (arp_table[i].state == ETHARP_STATE_STABLE) {
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/* if given, does IP address match IP address in ARP entry? */
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if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
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/* found exact IP address match, simply bail out */
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return i;
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/* remember entry with oldest stable entry in oldest, its age in maxtime */
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} else if (arp_table[i].ctime >= age_stable) {
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old_stable = i;
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age_stable = arp_table[i].ctime;
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}
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}
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}
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/* { we have no match } => try to create a new entry */
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/* no empty entry found and not allowed to recycle? */
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if ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0))
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{
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return (s8_t)ERR_MEM;
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}
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/* b) choose the least destructive entry to recycle:
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* 1) empty entry
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* 2) oldest stable entry
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* 3) oldest pending entry without queued packets
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* 4) oldest pending entry without queued packets
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*
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* { ETHARP_TRY_HARD is set at this point }
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*/
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/* 1) empty entry available? */
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if (empty < ARP_TABLE_SIZE) {
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i = empty;
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
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}
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/* 2) found recyclable stable entry? */
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else if (old_stable < ARP_TABLE_SIZE) {
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/* recycle oldest stable*/
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i = old_stable;
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
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#if ARP_QUEUEING
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/* no queued packets should exist on stable entries */
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LWIP_ASSERT("arp_table[i].p == NULL", arp_table[i].p == NULL);
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#endif
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/* 3) found recyclable pending entry without queued packets? */
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} else if (old_pending < ARP_TABLE_SIZE) {
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/* recycle oldest pending */
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i = old_pending;
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
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#if ARP_QUEUEING
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/* 4) found recyclable pending entry with queued packets? */
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} else if (old_queue < ARP_TABLE_SIZE) {
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/* recycle oldest pending */
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i = old_queue;
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].p)));
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pbuf_free(arp_table[i].p);
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arp_table[i].p = NULL;
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#endif
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/* no empty or recyclable entries found */
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} else {
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return (s8_t)ERR_MEM;
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}
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/* { empty or recyclable entry found } */
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LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
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if (arp_table[i].state != ETHARP_STATE_EMPTY)
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{
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snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
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}
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/* recycle entry (no-op for an already empty entry) */
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arp_table[i].state = ETHARP_STATE_EMPTY;
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/* IP address given? */
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if (ipaddr != NULL) {
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/* set IP address */
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ip_addr_set(&arp_table[i].ipaddr, ipaddr);
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}
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arp_table[i].ctime = 0;
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return (err_t)i;
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}
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/**
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* Update (or insert) a IP/MAC address pair in the ARP cache.
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*
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* If a pending entry is resolved, any queued packets will be sent
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* at this point.
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*
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* @param ipaddr IP address of the inserted ARP entry.
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* @param ethaddr Ethernet address of the inserted ARP entry.
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* @param flags Defines behaviour:
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* - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
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* only existing ARP entries will be updated.
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*
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* @return
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* - ERR_OK Succesfully updated ARP cache.
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* - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
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* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
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*
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* @see pbuf_free()
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*/
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static err_t
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update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
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{
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s8_t i;
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u8_t k;
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("update_arp_entry()\n"));
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LWIP_ASSERT("netif->hwaddr_len != 0", netif->hwaddr_len != 0);
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n",
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ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr),
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ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
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ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
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/* non-unicast address? */
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if (ip_addr_isany(ipaddr) ||
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ip_addr_isbroadcast(ipaddr, netif) ||
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ip_addr_ismulticast(ipaddr)) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
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return ERR_ARG;
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}
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/* find or create ARP entry */
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i = find_entry(ipaddr, flags);
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/* bail out if no entry could be found */
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if (i < 0) return (err_t)i;
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/* mark it stable */
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arp_table[i].state = ETHARP_STATE_STABLE;
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/* record network interface */
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arp_table[i].netif = netif;
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/* insert in SNMP ARP index tree */
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snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
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/* update address */
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k = netif->hwaddr_len;
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while (k > 0) {
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k--;
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arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
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}
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/* reset time stamp */
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arp_table[i].ctime = 0;
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/* this is where we will send out queued packets! */
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#if ARP_QUEUEING
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while (arp_table[i].p != NULL) {
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/* get the first packet on the queue */
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struct pbuf *p = arp_table[i].p;
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/* Ethernet header */
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struct eth_hdr *ethhdr = p->payload;
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/* remember (and reference) remainder of queue */
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/* note: this will also terminate the p pbuf chain */
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arp_table[i].p = pbuf_dequeue(p);
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/* fill-in Ethernet header */
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k = netif->hwaddr_len;
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while(k > 0) {
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k--;
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ethhdr->dest.addr[k] = ethaddr->addr[k];
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ethhdr->src.addr[k] = netif->hwaddr[k];
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}
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ethhdr->type = htons(ETHTYPE_IP);
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: sending queued IP packet %p.\n", (void *)p));
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/* send the queued IP packet */
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netif->linkoutput(netif, p);
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/* free the queued IP packet */
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pbuf_free(p);
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}
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#endif
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return ERR_OK;
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}
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/**
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* Finds (stable) ethernet/IP address pair from ARP table
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* using interface and IP address index.
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* @note the addresses in the ARP table are in network order!
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*
|
|
* @param netif points to interface index
|
|
* @param ipaddr points to the (network order) IP address index
|
|
* @param eth_ret points to return pointer
|
|
* @param ip_ret points to return pointer
|
|
* @return table index if found, -1 otherwise
|
|
*/
|
|
s8_t
|
|
etharp_find_addr(struct netif *netif, struct ip_addr *ipaddr,
|
|
struct eth_addr **eth_ret, struct ip_addr **ip_ret)
|
|
{
|
|
s8_t i;
|
|
|
|
i = 0;
|
|
while (i < ARP_TABLE_SIZE)
|
|
{
|
|
if ((arp_table[i].state == ETHARP_STATE_STABLE) &&
|
|
(arp_table[i].netif == netif) &&
|
|
ip_addr_cmp(ipaddr, &arp_table[i].ipaddr) )
|
|
{
|
|
*eth_ret = &arp_table[i].ethaddr;
|
|
*ip_ret = &arp_table[i].ipaddr;
|
|
return i;
|
|
}
|
|
i++;
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
/**
|
|
* Updates the ARP table using the given IP packet.
|
|
*
|
|
* Uses the incoming IP packet's source address to update the
|
|
* ARP cache for the local network. The function does not alter
|
|
* or free the packet. This function must be called before the
|
|
* packet p is passed to the IP layer.
|
|
*
|
|
* @param netif The lwIP network interface on which the IP packet pbuf arrived.
|
|
* @param pbuf The IP packet that arrived on netif.
|
|
*
|
|
* @return NULL
|
|
*
|
|
* @see pbuf_free()
|
|
*/
|
|
void
|
|
etharp_ip_input(struct netif *netif, struct pbuf *p)
|
|
{
|
|
struct ethip_hdr *hdr;
|
|
LWIP_ASSERT("netif != NULL", netif != NULL);
|
|
/* Only insert an entry if the source IP address of the
|
|
incoming IP packet comes from a host on the local network. */
|
|
hdr = p->payload;
|
|
/* source is not on the local network? */
|
|
if (!ip_addr_netcmp(&(hdr->ip.src), &(netif->ip_addr), &(netif->netmask))) {
|
|
/* do nothing */
|
|
return;
|
|
}
|
|
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
|
|
/* update ARP table */
|
|
/* @todo We could use ETHARP_TRY_HARD if we think we are going to talk
|
|
* back soon (for example, if the destination IP address is ours. */
|
|
update_arp_entry(netif, &(hdr->ip.src), &(hdr->eth.src), 0);
|
|
}
|
|
|
|
|
|
/**
|
|
* Responds to ARP requests to us. Upon ARP replies to us, add entry to cache
|
|
* send out queued IP packets. Updates cache with snooped address pairs.
|
|
*
|
|
* Should be called for incoming ARP packets. The pbuf in the argument
|
|
* is freed by this function.
|
|
*
|
|
* @param netif The lwIP network interface on which the ARP packet pbuf arrived.
|
|
* @param pbuf The ARP packet that arrived on netif. Is freed by this function.
|
|
* @param ethaddr Ethernet address of netif.
|
|
*
|
|
* @return NULL
|
|
*
|
|
* @see pbuf_free()
|
|
*/
|
|
void
|
|
etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
|
|
{
|
|
struct etharp_hdr *hdr;
|
|
/* these are aligned properly, whereas the ARP header fields might not be */
|
|
struct ip_addr sipaddr, dipaddr;
|
|
u8_t i;
|
|
u8_t for_us;
|
|
|
|
LWIP_ASSERT("netif != NULL", netif != NULL);
|
|
|
|
/* drop short ARP packets */
|
|
if (p->tot_len < sizeof(struct etharp_hdr)) {
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 1, ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len, (s16_t)sizeof(struct etharp_hdr)));
|
|
pbuf_free(p);
|
|
return;
|
|
}
|
|
|
|
hdr = p->payload;
|
|
|
|
/* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
|
|
* structure packing (not using structure copy which breaks strict-aliasing rules). */
|
|
memcpy(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
|
|
memcpy(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
|
|
|
|
/* this interface is not configured? */
|
|
if (netif->ip_addr.addr == 0) {
|
|
for_us = 0;
|
|
} else {
|
|
/* ARP packet directed to us? */
|
|
for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr));
|
|
}
|
|
|
|
/* ARP message directed to us? */
|
|
if (for_us) {
|
|
/* add IP address in ARP cache; assume requester wants to talk to us.
|
|
* can result in directly sending the queued packets for this host. */
|
|
update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD);
|
|
/* ARP message not directed to us? */
|
|
} else {
|
|
/* update the source IP address in the cache, if present */
|
|
update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), 0);
|
|
}
|
|
|
|
/* now act on the message itself */
|
|
switch (htons(hdr->opcode)) {
|
|
/* ARP request? */
|
|
case ARP_REQUEST:
|
|
/* ARP request. If it asked for our address, we send out a
|
|
* reply. In any case, we time-stamp any existing ARP entry,
|
|
* and possiby send out an IP packet that was queued on it. */
|
|
|
|
LWIP_DEBUGF (ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
|
|
/* ARP request for our address? */
|
|
if (for_us) {
|
|
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
|
|
/* re-use pbuf to send ARP reply */
|
|
hdr->opcode = htons(ARP_REPLY);
|
|
|
|
hdr->dipaddr = hdr->sipaddr;
|
|
hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr;
|
|
|
|
i = netif->hwaddr_len;
|
|
while(i > 0) {
|
|
i--;
|
|
hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
|
|
hdr->shwaddr.addr[i] = ethaddr->addr[i];
|
|
hdr->ethhdr.dest.addr[i] = hdr->dhwaddr.addr[i];
|
|
hdr->ethhdr.src.addr[i] = ethaddr->addr[i];
|
|
}
|
|
|
|
hdr->hwtype = htons(HWTYPE_ETHERNET);
|
|
ARPH_HWLEN_SET(hdr, netif->hwaddr_len);
|
|
|
|
hdr->proto = htons(ETHTYPE_IP);
|
|
ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr));
|
|
|
|
hdr->ethhdr.type = htons(ETHTYPE_ARP);
|
|
/* return ARP reply */
|
|
netif->linkoutput(netif, p);
|
|
/* we are not configured? */
|
|
} else if (netif->ip_addr.addr == 0) {
|
|
/* { for_us == 0 and netif->ip_addr.addr == 0 } */
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
|
|
/* request was not directed to us */
|
|
} else {
|
|
/* { for_us == 0 and netif->ip_addr.addr != 0 } */
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
|
|
}
|
|
break;
|
|
case ARP_REPLY:
|
|
/* ARP reply. We already updated the ARP cache earlier. */
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
|
|
#if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
|
|
/* DHCP wants to know about ARP replies from any host with an
|
|
* IP address also offered to us by the DHCP server. We do not
|
|
* want to take a duplicate IP address on a single network.
|
|
* @todo How should we handle redundant (fail-over) interfaces?
|
|
* */
|
|
dhcp_arp_reply(netif, &sipaddr);
|
|
#endif
|
|
break;
|
|
default:
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
|
|
break;
|
|
}
|
|
/* free ARP packet */
|
|
pbuf_free(p);
|
|
}
|
|
|
|
/**
|
|
* Resolve and fill-in Ethernet address header for outgoing packet.
|
|
*
|
|
* For IP multicast and broadcast, corresponding Ethernet addresses
|
|
* are selected and the packet is transmitted on the link.
|
|
*
|
|
* For unicast addresses, the packet is submitted to etharp_query(). In
|
|
* case the IP address is outside the local network, the IP address of
|
|
* the gateway is used.
|
|
*
|
|
* @param netif The lwIP network interface which the IP packet will be sent on.
|
|
* @param ipaddr The IP address of the packet destination.
|
|
* @param pbuf The pbuf(s) containing the IP packet to be sent.
|
|
*
|
|
* @return
|
|
* - ERR_RTE No route to destination (no gateway to external networks),
|
|
* or the return type of either etharp_query() or netif->linkoutput().
|
|
*/
|
|
err_t
|
|
etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
|
|
{
|
|
struct eth_addr *dest, *srcaddr, mcastaddr;
|
|
struct eth_hdr *ethhdr;
|
|
u8_t i;
|
|
|
|
/* make room for Ethernet header - should not fail */
|
|
if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
|
|
/* bail out */
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n"));
|
|
LINK_STATS_INC(link.lenerr);
|
|
return ERR_BUF;
|
|
}
|
|
|
|
/* assume unresolved Ethernet address */
|
|
dest = NULL;
|
|
/* Determine on destination hardware address. Broadcasts and multicasts
|
|
* are special, other IP addresses are looked up in the ARP table. */
|
|
|
|
/* broadcast destination IP address? */
|
|
if (ip_addr_isbroadcast(ipaddr, netif)) {
|
|
/* broadcast on Ethernet also */
|
|
dest = (struct eth_addr *)ðbroadcast;
|
|
/* multicast destination IP address? */
|
|
} else if (ip_addr_ismulticast(ipaddr)) {
|
|
/* Hash IP multicast address to MAC address.*/
|
|
mcastaddr.addr[0] = 0x01;
|
|
mcastaddr.addr[1] = 0x00;
|
|
mcastaddr.addr[2] = 0x5e;
|
|
mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
|
|
mcastaddr.addr[4] = ip4_addr3(ipaddr);
|
|
mcastaddr.addr[5] = ip4_addr4(ipaddr);
|
|
/* destination Ethernet address is multicast */
|
|
dest = &mcastaddr;
|
|
/* unicast destination IP address? */
|
|
} else {
|
|
/* outside local network? */
|
|
if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
|
|
/* interface has default gateway? */
|
|
if (netif->gw.addr != 0) {
|
|
/* send to hardware address of default gateway IP address */
|
|
ipaddr = &(netif->gw);
|
|
/* no default gateway available */
|
|
} else {
|
|
/* no route to destination error (default gateway missing) */
|
|
return ERR_RTE;
|
|
}
|
|
}
|
|
/* queue on destination Ethernet address belonging to ipaddr */
|
|
return etharp_query(netif, ipaddr, q);
|
|
}
|
|
|
|
/* continuation for multicast/broadcast destinations */
|
|
/* obtain source Ethernet address of the given interface */
|
|
srcaddr = (struct eth_addr *)netif->hwaddr;
|
|
ethhdr = q->payload;
|
|
i = netif->hwaddr_len;
|
|
while(i > 0) {
|
|
i--;
|
|
ethhdr->dest.addr[i] = dest->addr[i];
|
|
ethhdr->src.addr[i] = srcaddr->addr[i];
|
|
}
|
|
ethhdr->type = htons(ETHTYPE_IP);
|
|
/* send packet directly on the link */
|
|
return netif->linkoutput(netif, q);
|
|
}
|
|
|
|
/**
|
|
* Send an ARP request for the given IP address and/or queue a packet.
|
|
*
|
|
* If the IP address was not yet in the cache, a pending ARP cache entry
|
|
* is added and an ARP request is sent for the given address. The packet
|
|
* is queued on this entry.
|
|
*
|
|
* If the IP address was already pending in the cache, a new ARP request
|
|
* is sent for the given address. The packet is queued on this entry.
|
|
*
|
|
* If the IP address was already stable in the cache, and a packet is
|
|
* given, it is directly sent and no ARP request is sent out.
|
|
*
|
|
* If the IP address was already stable in the cache, and no packet is
|
|
* given, an ARP request is sent out.
|
|
*
|
|
* @param netif The lwIP network interface on which ipaddr
|
|
* must be queried for.
|
|
* @param ipaddr The IP address to be resolved.
|
|
* @param q If non-NULL, a pbuf that must be delivered to the IP address.
|
|
* q is not freed by this function.
|
|
*
|
|
* @return
|
|
* - ERR_BUF Could not make room for Ethernet header.
|
|
* - ERR_MEM Hardware address unknown, and no more ARP entries available
|
|
* to query for address or queue the packet.
|
|
* - ERR_MEM Could not queue packet due to memory shortage.
|
|
* - ERR_RTE No route to destination (no gateway to external networks).
|
|
* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
|
|
*
|
|
*/
|
|
err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
|
|
{
|
|
struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
|
|
err_t result = ERR_MEM;
|
|
s8_t i; /* ARP entry index */
|
|
u8_t k; /* Ethernet address octet index */
|
|
|
|
/* non-unicast address? */
|
|
if (ip_addr_isbroadcast(ipaddr, netif) ||
|
|
ip_addr_ismulticast(ipaddr) ||
|
|
ip_addr_isany(ipaddr)) {
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
|
|
return ERR_ARG;
|
|
}
|
|
|
|
/* find entry in ARP cache, ask to create entry if queueing packet */
|
|
i = find_entry(ipaddr, ETHARP_TRY_HARD);
|
|
|
|
/* could not find or create entry? */
|
|
if (i < 0)
|
|
{
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
|
|
if (q) LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: packet dropped\n"));
|
|
return (err_t)i;
|
|
}
|
|
|
|
/* mark a fresh entry as pending (we just sent a request) */
|
|
if (arp_table[i].state == ETHARP_STATE_EMPTY) {
|
|
arp_table[i].state = ETHARP_STATE_PENDING;
|
|
}
|
|
|
|
/* { i is either a STABLE or (new or existing) PENDING entry } */
|
|
LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
|
|
((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);
|
|
}
|
|
|
|
/* packet given? */
|
|
if (q != NULL) {
|
|
/* stable entry? */
|
|
if (arp_table[i].state == ETHARP_STATE_STABLE) {
|
|
/* we have a valid IP->Ethernet address mapping,
|
|
* fill in the Ethernet header for the outgoing packet */
|
|
struct eth_hdr *ethhdr = q->payload;
|
|
k = netif->hwaddr_len;
|
|
while(k > 0) {
|
|
k--;
|
|
ethhdr->dest.addr[k] = arp_table[i].ethaddr.addr[k];
|
|
ethhdr->src.addr[k] = srcaddr->addr[k];
|
|
}
|
|
ethhdr->type = htons(ETHTYPE_IP);
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: sending packet %p\n", (void *)q));
|
|
/* send the packet */
|
|
result = netif->linkoutput(netif, q);
|
|
/* pending entry? (either just created or already pending */
|
|
} else if (arp_table[i].state == ETHARP_STATE_PENDING) {
|
|
#if ARP_QUEUEING /* queue the given q packet */
|
|
struct pbuf *p;
|
|
/* copy any PBUF_REF referenced payloads into PBUF_RAM */
|
|
/* (the caller of lwIP assumes the referenced payload can be
|
|
* freed after it returns from the lwIP call that brought us here) */
|
|
p = pbuf_take(q);
|
|
/* packet could be taken over? */
|
|
if (p != NULL) {
|
|
/* queue packet ... */
|
|
if (arp_table[i].p == NULL) {
|
|
/* ... in the empty queue */
|
|
pbuf_ref(p);
|
|
arp_table[i].p = p;
|
|
#if 0 /* multi-packet-queueing disabled, see bug #11400 */
|
|
} else {
|
|
/* ... at tail of non-empty queue */
|
|
pbuf_queue(arp_table[i].p, p);
|
|
#endif
|
|
}
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
|
|
result = ERR_OK;
|
|
} else {
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
|
|
/* { result == ERR_MEM } through initialization */
|
|
}
|
|
#else /* ARP_QUEUEING == 0 */
|
|
/* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
|
|
/* { result == ERR_MEM } through initialization */
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
|
|
#endif
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
err_t etharp_request(struct netif *netif, struct ip_addr *ipaddr)
|
|
{
|
|
struct pbuf *p;
|
|
struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
|
|
err_t result = ERR_OK;
|
|
u8_t k; /* ARP entry index */
|
|
|
|
/* allocate a pbuf for the outgoing ARP request packet */
|
|
p = pbuf_alloc(PBUF_LINK, sizeof(struct etharp_hdr), PBUF_RAM);
|
|
/* could allocate a pbuf for an ARP request? */
|
|
if (p != NULL) {
|
|
struct etharp_hdr *hdr = p->payload;
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_request: sending ARP request.\n"));
|
|
hdr->opcode = htons(ARP_REQUEST);
|
|
k = netif->hwaddr_len;
|
|
while(k > 0) {
|
|
k--;
|
|
hdr->shwaddr.addr[k] = srcaddr->addr[k];
|
|
/* the hardware address is what we ask for, in
|
|
* a request it is a don't-care value, we use zeroes */
|
|
hdr->dhwaddr.addr[k] = 0x00;
|
|
}
|
|
hdr->dipaddr = *(struct ip_addr2 *)ipaddr;
|
|
hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr;
|
|
|
|
hdr->hwtype = htons(HWTYPE_ETHERNET);
|
|
ARPH_HWLEN_SET(hdr, netif->hwaddr_len);
|
|
|
|
hdr->proto = htons(ETHTYPE_IP);
|
|
ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr));
|
|
k = netif->hwaddr_len;
|
|
while(k > 0) {
|
|
k--;
|
|
/* broadcast to all network interfaces on the local network */
|
|
hdr->ethhdr.dest.addr[k] = 0xff;
|
|
hdr->ethhdr.src.addr[k] = srcaddr->addr[k];
|
|
}
|
|
hdr->ethhdr.type = htons(ETHTYPE_ARP);
|
|
/* send ARP query */
|
|
result = netif->linkoutput(netif, p);
|
|
/* free ARP query packet */
|
|
pbuf_free(p);
|
|
p = NULL;
|
|
/* could not allocate pbuf for ARP request */
|
|
} else {
|
|
result = ERR_MEM;
|
|
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_request: could not allocate pbuf for ARP request.\n"));
|
|
}
|
|
return result;
|
|
}
|