--- /dev/null
+/**
+ * @file
+ * Address Resolution Protocol module for IP over Ethernet
+ *
+ * Functionally, ARP is divided into two parts. The first maps an IP address
+ * to a physical address when sending a packet, and the second part answers
+ * requests from other machines for our physical address.
+ *
+ * This implementation complies with RFC 826 (Ethernet ARP). It supports
+ * Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6
+ * if an interface calls etharp_query(our_netif, its_ip_addr, NULL) upon
+ * address change.
+ */
+
+/*
+ * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
+ * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv>
+ * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ *
+ */
+
+#include "lwip/opt.h"
+
+#if LWIP_ARP /* don't build if not configured for use in lwipopts.h */
+
+#include "lwip/inet.h"
+#include "lwip/ip.h"
+#include "lwip/stats.h"
+#include "lwip/snmp.h"
+#include "lwip/dhcp.h"
+#include "lwip/autoip.h"
+#include "netif/etharp.h"
+
+#if PPPOE_SUPPORT
+#include "netif/ppp_oe.h"
+#endif /* PPPOE_SUPPORT */
+
+#include <string.h>
+
+/** the time an ARP entry stays valid after its last update,
+ * for ARP_TMR_INTERVAL = 5000, this is
+ * (240 * 5) seconds = 20 minutes.
+ */
+#define ARP_MAXAGE 240
+/** the time an ARP entry stays pending after first request,
+ * for ARP_TMR_INTERVAL = 5000, this is
+ * (2 * 5) seconds = 10 seconds.
+ *
+ * @internal Keep this number at least 2, otherwise it might
+ * run out instantly if the timeout occurs directly after a request.
+ */
+#define ARP_MAXPENDING 2
+
+#define HWTYPE_ETHERNET 1
+
+#define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8)
+#define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff)
+
+#define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8))
+#define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8))
+
+enum etharp_state {
+ ETHARP_STATE_EMPTY = 0,
+ ETHARP_STATE_PENDING,
+ ETHARP_STATE_STABLE
+};
+
+struct etharp_entry {
+#if ARP_QUEUEING
+ /**
+ * Pointer to queue of pending outgoing packets on this ARP entry.
+ */
+ struct etharp_q_entry *q;
+#endif
+ struct ip_addr ipaddr;
+ struct eth_addr ethaddr;
+ enum etharp_state state;
+ u8_t ctime;
+ struct netif *netif;
+};
+
+const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
+const struct eth_addr ethzero = {{0,0,0,0,0,0}};
+static struct etharp_entry arp_table[ARP_TABLE_SIZE];
+#if !LWIP_NETIF_HWADDRHINT
+static u8_t etharp_cached_entry;
+#endif
+
+/**
+ * Try hard to create a new entry - we want the IP address to appear in
+ * the cache (even if this means removing an active entry or so). */
+#define ETHARP_TRY_HARD 1
+#define ETHARP_FIND_ONLY 2
+
+#if LWIP_NETIF_HWADDRHINT
+#define NETIF_SET_HINT(netif, hint) if (((netif) != NULL) && ((netif)->addr_hint != NULL)) \
+ *((netif)->addr_hint) = (hint);
+static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif);
+#else /* LWIP_NETIF_HWADDRHINT */
+static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags);
+#endif /* LWIP_NETIF_HWADDRHINT */
+
+static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags);
+
+
+/* Some checks, instead of etharp_init(): */
+#if (LWIP_ARP && (ARP_TABLE_SIZE > 0x7f))
+ #error "If you want to use ARP, ARP_TABLE_SIZE must fit in an s8_t, so, you have to reduce it in your lwipopts.h"
+#endif
+
+
+#if ARP_QUEUEING
+/**
+ * Free a complete queue of etharp entries
+ *
+ * @param q a qeueue of etharp_q_entry's to free
+ */
+static void
+free_etharp_q(struct etharp_q_entry *q)
+{
+ struct etharp_q_entry *r;
+ LWIP_ASSERT("q != NULL", q != NULL);
+ LWIP_ASSERT("q->p != NULL", q->p != NULL);
+ while (q) {
+ r = q;
+ q = q->next;
+ LWIP_ASSERT("r->p != NULL", (r->p != NULL));
+ pbuf_free(r->p);
+ memp_free(MEMP_ARP_QUEUE, r);
+ }
+}
+#endif
+
+/**
+ * Clears expired entries in the ARP table.
+ *
+ * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
+ * in order to expire entries in the ARP table.
+ */
+void
+etharp_tmr(void)
+{
+ u8_t i;
+
+ LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
+ /* remove expired entries from the ARP table */
+ for (i = 0; i < ARP_TABLE_SIZE; ++i) {
+ arp_table[i].ctime++;
+ if (((arp_table[i].state == ETHARP_STATE_STABLE) &&
+ (arp_table[i].ctime >= ARP_MAXAGE)) ||
+ ((arp_table[i].state == ETHARP_STATE_PENDING) &&
+ (arp_table[i].ctime >= ARP_MAXPENDING))) {
+ /* pending or stable entry has become old! */
+ LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
+ arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
+ /* clean up entries that have just been expired */
+ /* remove from SNMP ARP index tree */
+ snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
+#if ARP_QUEUEING
+ /* and empty packet queue */
+ if (arp_table[i].q != NULL) {
+ /* remove all queued packets */
+ LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
+ free_etharp_q(arp_table[i].q);
+ arp_table[i].q = NULL;
+ }
+#endif
+ /* recycle entry for re-use */
+ arp_table[i].state = ETHARP_STATE_EMPTY;
+ }
+#if ARP_QUEUEING
+ /* still pending entry? (not expired) */
+ if (arp_table[i].state == ETHARP_STATE_PENDING) {
+ /* resend an ARP query here? */
+ }
+#endif
+ }
+}
+
+/**
+ * Search the ARP table for a matching or new entry.
+ *
+ * If an IP address is given, return a pending or stable ARP entry that matches
+ * the address. If no match is found, create a new entry with this address set,
+ * but in state ETHARP_EMPTY. The caller must check and possibly change the
+ * state of the returned entry.
+ *
+ * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
+ *
+ * In all cases, attempt to create new entries from an empty entry. If no
+ * empty entries are available and ETHARP_TRY_HARD flag is set, recycle
+ * old entries. Heuristic choose the least important entry for recycling.
+ *
+ * @param ipaddr IP address to find in ARP cache, or to add if not found.
+ * @param flags
+ * - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of
+ * active (stable or pending) entries.
+ *
+ * @return The ARP entry index that matched or is created, ERR_MEM if no
+ * entry is found or could be recycled.
+ */
+static s8_t
+#if LWIP_NETIF_HWADDRHINT
+find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif)
+#else /* LWIP_NETIF_HWADDRHINT */
+find_entry(struct ip_addr *ipaddr, u8_t flags)
+#endif /* LWIP_NETIF_HWADDRHINT */
+{
+ s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
+ s8_t empty = ARP_TABLE_SIZE;
+ u8_t i = 0, age_pending = 0, age_stable = 0;
+#if ARP_QUEUEING
+ /* oldest entry with packets on queue */
+ s8_t old_queue = ARP_TABLE_SIZE;
+ /* its age */
+ u8_t age_queue = 0;
+#endif
+
+ /* First, test if the last call to this function asked for the
+ * same address. If so, we're really fast! */
+ if (ipaddr) {
+ /* ipaddr to search for was given */
+#if LWIP_NETIF_HWADDRHINT
+ if ((netif != NULL) && (netif->addr_hint != NULL)) {
+ /* per-pcb cached entry was given */
+ u8_t per_pcb_cache = *(netif->addr_hint);
+ if ((per_pcb_cache < ARP_TABLE_SIZE) && arp_table[per_pcb_cache].state == ETHARP_STATE_STABLE) {
+ /* the per-pcb-cached entry is stable */
+ if (ip_addr_cmp(ipaddr, &arp_table[per_pcb_cache].ipaddr)) {
+ /* per-pcb cached entry was the right one! */
+ ETHARP_STATS_INC(etharp.cachehit);
+ return per_pcb_cache;
+ }
+ }
+ }
+#else /* #if LWIP_NETIF_HWADDRHINT */
+ if (arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) {
+ /* the cached entry is stable */
+ if (ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr)) {
+ /* cached entry was the right one! */
+ ETHARP_STATS_INC(etharp.cachehit);
+ return etharp_cached_entry;
+ }
+ }
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+ }
+
+ /**
+ * a) do a search through the cache, remember candidates
+ * b) select candidate entry
+ * c) create new entry
+ */
+
+ /* a) in a single search sweep, do all of this
+ * 1) remember the first empty entry (if any)
+ * 2) remember the oldest stable entry (if any)
+ * 3) remember the oldest pending entry without queued packets (if any)
+ * 4) remember the oldest pending entry with queued packets (if any)
+ * 5) search for a matching IP entry, either pending or stable
+ * until 5 matches, or all entries are searched for.
+ */
+
+ for (i = 0; i < ARP_TABLE_SIZE; ++i) {
+ /* no empty entry found yet and now we do find one? */
+ if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) {
+ LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
+ /* remember first empty entry */
+ empty = i;
+ }
+ /* pending entry? */
+ else if (arp_table[i].state == ETHARP_STATE_PENDING) {
+ /* if given, does IP address match IP address in ARP entry? */
+ if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
+ /* found exact IP address match, simply bail out */
+#if LWIP_NETIF_HWADDRHINT
+ NETIF_SET_HINT(netif, i);
+#else /* #if LWIP_NETIF_HWADDRHINT */
+ etharp_cached_entry = i;
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+ return i;
+#if ARP_QUEUEING
+ /* pending with queued packets? */
+ } else if (arp_table[i].q != NULL) {
+ if (arp_table[i].ctime >= age_queue) {
+ old_queue = i;
+ age_queue = arp_table[i].ctime;
+ }
+#endif
+ /* pending without queued packets? */
+ } else {
+ if (arp_table[i].ctime >= age_pending) {
+ old_pending = i;
+ age_pending = arp_table[i].ctime;
+ }
+ }
+ }
+ /* stable entry? */
+ else if (arp_table[i].state == ETHARP_STATE_STABLE) {
+ /* if given, does IP address match IP address in ARP entry? */
+ if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
+ /* found exact IP address match, simply bail out */
+#if LWIP_NETIF_HWADDRHINT
+ NETIF_SET_HINT(netif, i);
+#else /* #if LWIP_NETIF_HWADDRHINT */
+ etharp_cached_entry = i;
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+ return i;
+ /* remember entry with oldest stable entry in oldest, its age in maxtime */
+ } else if (arp_table[i].ctime >= age_stable) {
+ old_stable = i;
+ age_stable = arp_table[i].ctime;
+ }
+ }
+ }
+ /* { we have no match } => try to create a new entry */
+
+ /* no empty entry found and not allowed to recycle? */
+ if (((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0))
+ /* or don't create new entry, only search? */
+ || ((flags & ETHARP_FIND_ONLY) != 0)) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
+ return (s8_t)ERR_MEM;
+ }
+
+ /* b) choose the least destructive entry to recycle:
+ * 1) empty entry
+ * 2) oldest stable entry
+ * 3) oldest pending entry without queued packets
+ * 4) oldest pending entry without queued packets
+ *
+ * { ETHARP_TRY_HARD is set at this point }
+ */
+
+ /* 1) empty entry available? */
+ if (empty < ARP_TABLE_SIZE) {
+ i = empty;
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
+ }
+ /* 2) found recyclable stable entry? */
+ else if (old_stable < ARP_TABLE_SIZE) {
+ /* recycle oldest stable*/
+ i = old_stable;
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
+#if ARP_QUEUEING
+ /* no queued packets should exist on stable entries */
+ LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
+#endif
+ /* 3) found recyclable pending entry without queued packets? */
+ } else if (old_pending < ARP_TABLE_SIZE) {
+ /* recycle oldest pending */
+ i = old_pending;
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
+#if ARP_QUEUEING
+ /* 4) found recyclable pending entry with queued packets? */
+ } else if (old_queue < ARP_TABLE_SIZE) {
+ /* recycle oldest pending */
+ i = old_queue;
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].q)));
+ free_etharp_q(arp_table[i].q);
+ arp_table[i].q = NULL;
+#endif
+ /* no empty or recyclable entries found */
+ } else {
+ return (s8_t)ERR_MEM;
+ }
+
+ /* { empty or recyclable entry found } */
+ LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
+
+ if (arp_table[i].state != ETHARP_STATE_EMPTY)
+ {
+ snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
+ }
+ /* recycle entry (no-op for an already empty entry) */
+ arp_table[i].state = ETHARP_STATE_EMPTY;
+
+ /* IP address given? */
+ if (ipaddr != NULL) {
+ /* set IP address */
+ ip_addr_set(&arp_table[i].ipaddr, ipaddr);
+ }
+ arp_table[i].ctime = 0;
+#if LWIP_NETIF_HWADDRHINT
+ NETIF_SET_HINT(netif, i);
+#else /* #if LWIP_NETIF_HWADDRHINT */
+ etharp_cached_entry = i;
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+ return (err_t)i;
+}
+
+/**
+ * Send an IP packet on the network using netif->linkoutput
+ * The ethernet header is filled in before sending.
+ *
+ * @params netif the lwIP network interface on which to send the packet
+ * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
+ * @params src the source MAC address to be copied into the ethernet header
+ * @params dst the destination MAC address to be copied into the ethernet header
+ * @return ERR_OK if the packet was sent, any other err_t on failure
+ */
+static err_t
+etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
+{
+ struct eth_hdr *ethhdr = p->payload;
+ u8_t k;
+
+ LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
+ (netif->hwaddr_len == ETHARP_HWADDR_LEN));
+ k = ETHARP_HWADDR_LEN;
+ while(k > 0) {
+ k--;
+ ethhdr->dest.addr[k] = dst->addr[k];
+ ethhdr->src.addr[k] = src->addr[k];
+ }
+ ethhdr->type = htons(ETHTYPE_IP);
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
+ /* send the packet */
+ return netif->linkoutput(netif, p);
+}
+
+/**
+ * Update (or insert) a IP/MAC address pair in the ARP cache.
+ *
+ * If a pending entry is resolved, any queued packets will be sent
+ * at this point.
+ *
+ * @param ipaddr IP address of the inserted ARP entry.
+ * @param ethaddr Ethernet address of the inserted ARP entry.
+ * @param flags Defines behaviour:
+ * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
+ * only existing ARP entries will be updated.
+ *
+ * @return
+ * - ERR_OK Succesfully updated ARP cache.
+ * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
+ * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
+ *
+ * @see pbuf_free()
+ */
+static err_t
+update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
+{
+ s8_t i;
+ u8_t k;
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 3, ("update_arp_entry()\n"));
+ LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_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",
+ ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr),
+ ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
+ ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
+ /* non-unicast address? */
+ if (ip_addr_isany(ipaddr) ||
+ ip_addr_isbroadcast(ipaddr, netif) ||
+ ip_addr_ismulticast(ipaddr)) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
+ return ERR_ARG;
+ }
+ /* find or create ARP entry */
+#if LWIP_NETIF_HWADDRHINT
+ i = find_entry(ipaddr, flags, netif);
+#else /* LWIP_NETIF_HWADDRHINT */
+ i = find_entry(ipaddr, flags);
+#endif /* LWIP_NETIF_HWADDRHINT */
+ /* bail out if no entry could be found */
+ if (i < 0)
+ return (err_t)i;
+
+ /* mark it stable */
+ arp_table[i].state = ETHARP_STATE_STABLE;
+ /* record network interface */
+ arp_table[i].netif = netif;
+
+ /* insert in SNMP ARP index tree */
+ snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
+
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
+ /* update address */
+ k = ETHARP_HWADDR_LEN;
+ while (k > 0) {
+ k--;
+ arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
+ }
+ /* reset time stamp */
+ arp_table[i].ctime = 0;
+#if ARP_QUEUEING
+ /* this is where we will send out queued packets! */
+ while (arp_table[i].q != NULL) {
+ struct pbuf *p;
+ /* remember remainder of queue */
+ struct etharp_q_entry *q = arp_table[i].q;
+ /* pop first item off the queue */
+ arp_table[i].q = q->next;
+ /* get the packet pointer */
+ p = q->p;
+ /* now queue entry can be freed */
+ memp_free(MEMP_ARP_QUEUE, q);
+ /* send the queued IP packet */
+ etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
+ /* free the queued IP packet */
+ pbuf_free(p);
+ }
+#endif
+ return ERR_OK;
+}
+
+/**
+ * Finds (stable) ethernet/IP address pair from ARP table
+ * using interface and IP address index.
+ * @note the addresses in the ARP table are in network order!
+ *
+ * @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;
+
+ LWIP_UNUSED_ARG(netif);
+
+#if LWIP_NETIF_HWADDRHINT
+ i = find_entry(ipaddr, ETHARP_FIND_ONLY, NULL);
+#else /* LWIP_NETIF_HWADDRHINT */
+ i = find_entry(ipaddr, ETHARP_FIND_ONLY);
+#endif /* LWIP_NETIF_HWADDRHINT */
+ if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) {
+ *eth_ret = &arp_table[i].ethaddr;
+ *ip_ret = &arp_table[i].ipaddr;
+ return 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 p 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_ERROR("netif != NULL", (netif != NULL), return;);
+ /* 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 | LWIP_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 ethaddr Ethernet address of netif.
+ * @param p The ARP packet that arrived on netif. Is freed by this function.
+ *
+ * @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;
+#if LWIP_AUTOIP
+ const u8_t * ethdst_hwaddr;
+#endif /* LWIP_AUTOIP */
+
+ LWIP_ERROR("netif != NULL", (netif != NULL), return;);
+
+ /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
+ since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
+ if (p->len < sizeof(struct etharp_hdr)) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 1, ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len, (s16_t)sizeof(struct etharp_hdr)));
+ ETHARP_STATS_INC(etharp.lenerr);
+ ETHARP_STATS_INC(etharp.drop);
+ pbuf_free(p);
+ return;
+ }
+
+ hdr = p->payload;
+
+ /* RFC 826 "Packet Reception": */
+ if ((hdr->hwtype != htons(HWTYPE_ETHERNET)) ||
+ (hdr->_hwlen_protolen != htons((ETHARP_HWADDR_LEN << 8) | sizeof(struct ip_addr))) ||
+ (hdr->proto != htons(ETHTYPE_IP)) ||
+ (hdr->ethhdr.type != htons(ETHTYPE_ARP))) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 1,
+ ("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
+ hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr), hdr->ethhdr.type));
+ ETHARP_STATS_INC(etharp.proterr);
+ ETHARP_STATS_INC(etharp.drop);
+ pbuf_free(p);
+ return;
+ }
+ ETHARP_STATS_INC(etharp.recv);
+
+#if LWIP_AUTOIP
+ /* We have to check if a host already has configured our random
+ * created link local address and continously check if there is
+ * a host with this IP-address so we can detect collisions */
+ autoip_arp_reply(netif, hdr);
+#endif /* LWIP_AUTOIP */
+
+ /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
+ * structure packing (not using structure copy which breaks strict-aliasing rules). */
+ SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
+ SMEMCPY(&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 | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
+ /* ARP request for our address? */
+ if (for_us) {
+
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
+ /* Re-use pbuf to send ARP reply.
+ Since we are re-using an existing pbuf, we can't call etharp_raw since
+ that would allocate a new pbuf. */
+ hdr->opcode = htons(ARP_REPLY);
+
+ hdr->dipaddr = hdr->sipaddr;
+ hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr;
+
+ LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
+ (netif->hwaddr_len == ETHARP_HWADDR_LEN));
+ i = ETHARP_HWADDR_LEN;
+#if LWIP_AUTOIP
+ /* If we are using Link-Local, ARP packets must be broadcast on the
+ * link layer. (See RFC3927 Section 2.5) */
+ ethdst_hwaddr = ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
+#endif /* LWIP_AUTOIP */
+
+ while(i > 0) {
+ i--;
+ hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
+#if LWIP_AUTOIP
+ hdr->ethhdr.dest.addr[i] = ethdst_hwaddr[i];
+#else /* LWIP_AUTOIP */
+ hdr->ethhdr.dest.addr[i] = hdr->shwaddr.addr[i];
+#endif /* LWIP_AUTOIP */
+ hdr->shwaddr.addr[i] = ethaddr->addr[i];
+ hdr->ethhdr.src.addr[i] = ethaddr->addr[i];
+ }
+
+ /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
+ are already correct, we tested that before */
+
+ /* 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 | LWIP_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 | LWIP_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 | LWIP_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 | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
+ ETHARP_STATS_INC(etharp.err);
+ break;
+ }
+ /* free ARP packet */
+ pbuf_free(p);
+}
+
+/**
+ * Resolve and fill-in Ethernet address header for outgoing IP 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 q The pbuf(s) containing the IP packet to be sent.
+ * @param ipaddr The IP address of the packet destination.
+ *
+ * @return
+ * - ERR_RTE No route to destination (no gateway to external networks),
+ * or the return type of either etharp_query() or etharp_send_ip().
+ */
+err_t
+etharp_output(struct netif *netif, struct pbuf *q, struct ip_addr *ipaddr)
+{
+ struct eth_addr *dest, mcastaddr;
+
+ /* make room for Ethernet header - should not fail */
+ if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
+ /* bail out */
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_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 */
+ /* send packet directly on the link */
+ return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
+}
+
+/**
+ * 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.
+ *
+ * @note q must only be ONE packet, not a packet queue!
+ *
+ * @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 */
+
+ /* non-unicast address? */
+ if (ip_addr_isbroadcast(ipaddr, netif) ||
+ ip_addr_ismulticast(ipaddr) ||
+ ip_addr_isany(ipaddr)) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_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 */
+#if LWIP_NETIF_HWADDRHINT
+ i = find_entry(ipaddr, ETHARP_TRY_HARD, netif);
+#else /* LWIP_NETIF_HWADDRHINT */
+ i = find_entry(ipaddr, ETHARP_TRY_HARD);
+#endif /* LWIP_NETIF_HWADDRHINT */
+
+ /* could not find or create entry? */
+ if (i < 0) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
+ if (q) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
+ ETHARP_STATS_INC(etharp.memerr);
+ }
+ 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);
+ if (result != ERR_OK) {
+ /* ARP request couldn't be sent */
+ /* We don't re-send arp request in etharp_tmr, but we still queue packets,
+ since this failure could be temporary, and the next packet calling
+ etharp_query again could lead to sending the queued packets. */
+ }
+ }
+
+ /* packet given? */
+ if (q != NULL) {
+ /* stable entry? */
+ if (arp_table[i].state == ETHARP_STATE_STABLE) {
+ /* we have a valid IP->Ethernet address mapping */
+ /* send the packet */
+ result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
+ /* 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;
+ int copy_needed = 0;
+ /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
+ * to copy the whole queue into a new PBUF_RAM (see bug #11400)
+ * PBUF_ROMs can be left as they are, since ROM must not get changed. */
+ p = q;
+ while (p) {
+ LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
+ if(p->type != PBUF_ROM) {
+ copy_needed = 1;
+ break;
+ }
+ p = p->next;
+ }
+ if(copy_needed) {
+ /* copy the whole packet into new pbufs */
+ p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
+ if(p != NULL) {
+ if (pbuf_copy(p, q) != ERR_OK) {
+ pbuf_free(p);
+ p = NULL;
+ }
+ }
+ } else {
+ /* referencing the old pbuf is enough */
+ p = q;
+ pbuf_ref(p);
+ }
+ /* packet could be taken over? */
+ if (p != NULL) {
+ /* queue packet ... */
+ struct etharp_q_entry *new_entry;
+ /* allocate a new arp queue entry */
+ new_entry = memp_malloc(MEMP_ARP_QUEUE);
+ if (new_entry != NULL) {
+ new_entry->next = 0;
+ new_entry->p = p;
+ if(arp_table[i].q != NULL) {
+ /* queue was already existent, append the new entry to the end */
+ struct etharp_q_entry *r;
+ r = arp_table[i].q;
+ while (r->next != NULL) {
+ r = r->next;
+ }
+ r->next = new_entry;
+ } else {
+ /* queue did not exist, first item in queue */
+ arp_table[i].q = new_entry;
+ }
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
+ result = ERR_OK;
+ } else {
+ /* the pool MEMP_ARP_QUEUE is empty */
+ pbuf_free(p);
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_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 {
+ ETHARP_STATS_INC(etharp.memerr);
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_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 | LWIP_DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
+#endif
+ }
+ }
+ return result;
+}
+
+/**
+ * Send a raw ARP packet (opcode and all addresses can be modified)
+ *
+ * @param netif the lwip network interface on which to send the ARP packet
+ * @param ethsrc_addr the source MAC address for the ethernet header
+ * @param ethdst_addr the destination MAC address for the ethernet header
+ * @param hwsrc_addr the source MAC address for the ARP protocol header
+ * @param ipsrc_addr the source IP address for the ARP protocol header
+ * @param hwdst_addr the destination MAC address for the ARP protocol header
+ * @param ipdst_addr the destination IP address for the ARP protocol header
+ * @param opcode the type of the ARP packet
+ * @return ERR_OK if the ARP packet has been sent
+ * ERR_MEM if the ARP packet couldn't be allocated
+ * any other err_t on failure
+ */
+#if !LWIP_AUTOIP
+static
+#endif /* LWIP_AUTOIP */
+err_t
+etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
+ const struct eth_addr *ethdst_addr,
+ const struct eth_addr *hwsrc_addr, const struct ip_addr *ipsrc_addr,
+ const struct eth_addr *hwdst_addr, const struct ip_addr *ipdst_addr,
+ const u16_t opcode)
+{
+ struct pbuf *p;
+ err_t result = ERR_OK;
+ u8_t k; /* ARP entry index */
+ struct etharp_hdr *hdr;
+#if LWIP_AUTOIP
+ const u8_t * ethdst_hwaddr;
+#endif /* LWIP_AUTOIP */
+
+ /* 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) {
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 2, ("etharp_raw: could not allocate pbuf for ARP request.\n"));
+ ETHARP_STATS_INC(etharp.memerr);
+ return ERR_MEM;
+ }
+ LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
+ (p->len >= sizeof(struct etharp_hdr)));
+
+ hdr = p->payload;
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
+ hdr->opcode = htons(opcode);
+
+ LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
+ (netif->hwaddr_len == ETHARP_HWADDR_LEN));
+ k = ETHARP_HWADDR_LEN;
+#if LWIP_AUTOIP
+ /* If we are using Link-Local, ARP packets must be broadcast on the
+ * link layer. (See RFC3927 Section 2.5) */
+ ethdst_hwaddr = ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
+#endif /* LWIP_AUTOIP */
+ /* Write MAC-Addresses (combined loop for both headers) */
+ while(k > 0) {
+ k--;
+ /* Write the ARP MAC-Addresses */
+ hdr->shwaddr.addr[k] = hwsrc_addr->addr[k];
+ hdr->dhwaddr.addr[k] = hwdst_addr->addr[k];
+ /* Write the Ethernet MAC-Addresses */
+#if LWIP_AUTOIP
+ hdr->ethhdr.dest.addr[k] = ethdst_hwaddr[k];
+#else /* LWIP_AUTOIP */
+ hdr->ethhdr.dest.addr[k] = ethdst_addr->addr[k];
+#endif /* LWIP_AUTOIP */
+ hdr->ethhdr.src.addr[k] = ethsrc_addr->addr[k];
+ }
+ hdr->sipaddr = *(struct ip_addr2 *)ipsrc_addr;
+ hdr->dipaddr = *(struct ip_addr2 *)ipdst_addr;
+
+ hdr->hwtype = htons(HWTYPE_ETHERNET);
+ hdr->proto = htons(ETHTYPE_IP);
+ /* set hwlen and protolen together */
+ hdr->_hwlen_protolen = htons((ETHARP_HWADDR_LEN << 8) | sizeof(struct ip_addr));
+
+ hdr->ethhdr.type = htons(ETHTYPE_ARP);
+ /* send ARP query */
+ result = netif->linkoutput(netif, p);
+ ETHARP_STATS_INC(etharp.xmit);
+ /* free ARP query packet */
+ pbuf_free(p);
+ p = NULL;
+ /* could not allocate pbuf for ARP request */
+
+ return result;
+}
+
+/**
+ * Send an ARP request packet asking for ipaddr.
+ *
+ * @param netif the lwip network interface on which to send the request
+ * @param ipaddr the IP address for which to ask
+ * @return ERR_OK if the request has been sent
+ * ERR_MEM if the ARP packet couldn't be allocated
+ * any other err_t on failure
+ */
+err_t
+etharp_request(struct netif *netif, struct ip_addr *ipaddr)
+{
+ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
+ return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, ðbroadcast,
+ (struct eth_addr *)netif->hwaddr, &netif->ip_addr, ðzero,
+ ipaddr, ARP_REQUEST);
+}
+
+/**
+ * Process received ethernet frames. Using this function instead of directly
+ * calling ip_input and passing ARP frames through etharp in ethernetif_input,
+ * the ARP cache is protected from concurrent access.
+ *
+ * @param p the recevied packet, p->payload pointing to the ethernet header
+ * @param netif the network interface on which the packet was received
+ */
+err_t
+ethernet_input(struct pbuf *p, struct netif *netif)
+{
+ struct eth_hdr* ethhdr;
+
+ /* points to packet payload, which starts with an Ethernet header */
+ ethhdr = p->payload;
+
+ switch (htons(ethhdr->type)) {
+ /* IP packet? */
+ case ETHTYPE_IP:
+#if ETHARP_TRUST_IP_MAC
+ /* update ARP table */
+ etharp_ip_input(netif, p);
+#endif /* ETHARP_TRUST_IP_MAC */
+ /* skip Ethernet header */
+ if(pbuf_header(p, -(s16_t)sizeof(struct eth_hdr))) {
+ LWIP_ASSERT("Can't move over header in packet", 0);
+ pbuf_free(p);
+ p = NULL;
+ } else {
+ /* pass to IP layer */
+ ip_input(p, netif);
+ }
+ break;
+
+ case ETHTYPE_ARP:
+ /* pass p to ARP module */
+ etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
+ break;
+
+#if PPPOE_SUPPORT
+ case ETHTYPE_PPPOEDISC: /* PPP Over Ethernet Discovery Stage */
+ pppoe_disc_input(netif, p);
+ break;
+
+ case ETHTYPE_PPPOE: /* PPP Over Ethernet Session Stage */
+ pppoe_data_input(netif, p);
+ break;
+#endif /* PPPOE_SUPPORT */
+
+ default:
+ pbuf_free(p);
+ p = NULL;
+ break;
+ }
+
+ /* This means the pbuf is freed or consumed,
+ so the caller doesn't have to free it again */
+ return ERR_OK;
+}
+#endif /* LWIP_ARP */
