/** * @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_gratuitous(our_netif) upon address change. */ /* * Copyright (c) 2001-2003 Swedish Institute of Computer Science. * Copyright (c) 2003-2004 Leon Woestenberg * 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_IPV4 && LWIP_ARP /* don't build if not configured for use in lwipopts.h */ #include "lwip/etharp.h" #include "lwip/stats.h" #include "lwip/snmp.h" #include "lwip/dhcp.h" #include "lwip/autoip.h" #include "lwip/prot/iana.h" #include "netif/ethernet.h" #include #ifdef LWIP_HOOK_FILENAME #include LWIP_HOOK_FILENAME #endif /** Re-request a used ARP entry 1 minute before it would expire to prevent * breaking a steadily used connection because the ARP entry timed out. */ #define ARP_AGE_REREQUEST_USED_UNICAST (ARP_MAXAGE - 30) #define ARP_AGE_REREQUEST_USED_BROADCAST (ARP_MAXAGE - 15) /** the time an ARP entry stays pending after first request, * for ARP_TMR_INTERVAL = 1000, this is * 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 5 /** ARP states */ enum etharp_state { ETHARP_STATE_EMPTY = 0, ETHARP_STATE_PENDING, ETHARP_STATE_STABLE, ETHARP_STATE_STABLE_REREQUESTING_1, ETHARP_STATE_STABLE_REREQUESTING_2 #if ETHARP_SUPPORT_STATIC_ENTRIES , ETHARP_STATE_STATIC #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ }; struct etharp_entry { #if ARP_QUEUEING /** Pointer to queue of pending outgoing packets on this ARP entry. */ struct etharp_q_entry *q; #else /* ARP_QUEUEING */ /** Pointer to a single pending outgoing packet on this ARP entry. */ struct pbuf *q; #endif /* ARP_QUEUEING */ ip4_addr_t ipaddr; struct netif *netif; struct eth_addr ethaddr; u16_t ctime; u8_t state; }; static struct etharp_entry arp_table[ARP_TABLE_SIZE]; #if !LWIP_NETIF_HWADDRHINT static netif_addr_idx_t etharp_cached_entry; #endif /* !LWIP_NETIF_HWADDRHINT */ /** 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_FLAG_TRY_HARD 1 #define ETHARP_FLAG_FIND_ONLY 2 #if ETHARP_SUPPORT_STATIC_ENTRIES #define ETHARP_FLAG_STATIC_ENTRY 4 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ #if LWIP_NETIF_HWADDRHINT #define ETHARP_SET_ADDRHINT(netif, addrhint) do { if (((netif) != NULL) && ((netif)->hints != NULL)) { \ (netif)->hints->addr_hint = (addrhint); }} while(0) #else /* LWIP_NETIF_HWADDRHINT */ #define ETHARP_SET_ADDRHINT(netif, addrhint) (etharp_cached_entry = (addrhint)) #endif /* LWIP_NETIF_HWADDRHINT */ /* Check for maximum ARP_TABLE_SIZE */ #if (ARP_TABLE_SIZE > NETIF_ADDR_IDX_MAX) #error "ARP_TABLE_SIZE must fit in an s16_t, you have to reduce it in your lwipopts.h" #endif static err_t etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr *hw_dst_addr); static 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 ip4_addr_t *ipsrc_addr, const struct eth_addr *hwdst_addr, const ip4_addr_t *ipdst_addr, const u16_t opcode); #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); 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); } } #else /* ARP_QUEUEING */ /** Compatibility define: free the queued pbuf */ #define free_etharp_q(q) pbuf_free(q) #endif /* ARP_QUEUEING */ /** Clean up ARP table entries */ static void etharp_free_entry(int i) { /* remove from SNMP ARP index tree */ mib2_remove_arp_entry(arp_table[i].netif, &arp_table[i].ipaddr); /* and empty packet queue */ if (arp_table[i].q != NULL) { /* remove all queued packets */ LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_free_entry: 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; } /* recycle entry for re-use */ arp_table[i].state = ETHARP_STATE_EMPTY; #ifdef LWIP_DEBUG /* for debugging, clean out the complete entry */ arp_table[i].ctime = 0; arp_table[i].netif = NULL; ip4_addr_set_zero(&arp_table[i].ipaddr); arp_table[i].ethaddr = ethzero; #endif /* LWIP_DEBUG */ } #if LWIP_LOWPOWER #include "lwip/lowpower.h" u32_t etharp_tmr_tick(void) { s32_t i; u32_t tick = 0; u32_t time; for (i = 0; i < ARP_TABLE_SIZE; i++) { u8_t state = arp_table[i].state; if ((state != ETHARP_STATE_EMPTY) #if ETHARP_SUPPORT_STATIC_ENTRIES && (state != ETHARP_STATE_STATIC) #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ ) { if (arp_table[i].state != ETHARP_STATE_STABLE) { LWIP_DEBUGF(LOWPOWER_DEBUG, ("%s tmr tick: 1\n", "etharp_tmr_tick")); return 1; } time = (u32_t)ARP_MAXAGE - arp_table[i].ctime; SET_TMR_TICK(tick, time); } } LWIP_DEBUGF(LOWPOWER_DEBUG, ("%s tmr tick: %u\n", "etharp_tmr_tick", tick)); return tick; } #endif /* LWIP_LOWPOWER */ /** * Clears expired entries in the ARP table. * * This function should be called every ARP_TMR_INTERVAL milliseconds (1 second), * in order to expire entries in the ARP table. */ void etharp_tmr(void) { int i; LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n")); /* remove expired entries from the ARP table */ for (i = 0; i < ARP_TABLE_SIZE; ++i) { u8_t state = arp_table[i].state; if (state != ETHARP_STATE_EMPTY #if ETHARP_SUPPORT_STATIC_ENTRIES && (state != ETHARP_STATE_STATIC) #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ ) { arp_table[i].ctime++; if ((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 %d.\n", arp_table[i].state >= ETHARP_STATE_STABLE ? "stable" : "pending", i)); /* clean up entries that have just been expired */ etharp_free_entry(i); } else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING_1) { /* Don't send more than one request every 2 seconds. */ arp_table[i].state = ETHARP_STATE_STABLE_REREQUESTING_2; } else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING_2) { /* Reset state to stable, so that the next transmitted packet will re-send an ARP request. */ arp_table[i].state = ETHARP_STATE_STABLE; } else if (arp_table[i].state == ETHARP_STATE_PENDING) { /* still pending, resend an ARP query */ etharp_request(arp_table[i].netif, &arp_table[i].ipaddr); } } } } /** * 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_FLAG_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 See @ref etharp_state * @param netif netif related to this address (used for NETIF_HWADDRHINT) * * @return The ARP entry index that matched or is created, ERR_MEM if no * entry is found or could be recycled. */ static s16_t etharp_find_entry(const ip4_addr_t *ipaddr, u8_t flags, struct netif *netif) { s16_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE; s16_t empty = ARP_TABLE_SIZE; s16_t i = 0; /* oldest entry with packets on queue */ s16_t old_queue = ARP_TABLE_SIZE; /* its age */ u16_t age_queue = 0, age_pending = 0, age_stable = 0; LWIP_UNUSED_ARG(netif); /** * 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) { u8_t state = arp_table[i].state; /* no empty entry found yet and now we do find one? */ if ((empty == ARP_TABLE_SIZE) && (state == ETHARP_STATE_EMPTY)) { LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_find_entry: found empty entry %d\n", (int)i)); /* remember first empty entry */ empty = i; } else if (state != ETHARP_STATE_EMPTY) { LWIP_ASSERT("state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE", state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE); /* if given, does IP address match IP address in ARP entry? */ if (ipaddr && ip4_addr_cmp(ipaddr, &arp_table[i].ipaddr) #if ETHARP_TABLE_MATCH_NETIF && ((netif == NULL) || (netif == arp_table[i].netif)) #endif /* ETHARP_TABLE_MATCH_NETIF */ ) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: found matching entry %d\n", (int)i)); /* found exact IP address match, simply bail out */ return i; } /* pending entry? */ if (state == ETHARP_STATE_PENDING) { /* pending with queued packets? */ if (arp_table[i].q != NULL) { if (arp_table[i].ctime >= age_queue) { old_queue = i; age_queue = arp_table[i].ctime; } } else /* pending without queued packets? */ { if (arp_table[i].ctime >= age_pending) { old_pending = i; age_pending = arp_table[i].ctime; } } /* stable entry? */ } else if (state >= ETHARP_STATE_STABLE) { #if ETHARP_SUPPORT_STATIC_ENTRIES /* don't record old_stable for static entries since they never expire */ if (state < ETHARP_STATE_STATIC) #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ { /* remember entry with oldest stable entry in oldest, its age in maxtime */ 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 */ /* don't create new entry, only search? */ if (((flags & ETHARP_FLAG_FIND_ONLY) != 0) || /* or no empty entry found and not allowed to recycle? */ ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_FLAG_TRY_HARD) == 0))) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty entry found and not allowed to recycle\n")); return (s16_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 with queued packets * * { ETHARP_FLAG_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, ("etharp_find_entry: selecting empty entry %d\n", (int)i)); } else { /* 2) found recyclable stable entry? */ if (old_stable < ARP_TABLE_SIZE) { /* recycle oldest stable*/ i = old_stable; LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest stable entry %d\n", (int)i)); /* no queued packets should exist on stable entries */ LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL); /* 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, ("etharp_find_entry: selecting oldest pending entry %d (without queue)\n", (int)i)); /* 4) found recyclable pending entry with queued packets? */ } else if (old_queue < ARP_TABLE_SIZE) { /* recycle oldest pending (queued packets are free in etharp_free_entry) */ i = old_queue; LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %d, freeing packet queue %p\n", (int)i, (void *)(arp_table[i].q))); /* no empty or recyclable entries found */ } else { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty or recyclable entries found\n")); return (s16_t)ERR_MEM; } /* { empty or recyclable entry found } */ LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE); etharp_free_entry(i); } LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE); LWIP_ASSERT("arp_table[i].state == ETHARP_STATE_EMPTY", arp_table[i].state == ETHARP_STATE_EMPTY); /* IP address given? */ if (ipaddr != NULL) { /* set IP address */ ip4_addr_copy(arp_table[i].ipaddr, *ipaddr); } arp_table[i].ctime = 0; #if ETHARP_TABLE_MATCH_NETIF arp_table[i].netif = netif; #endif /* ETHARP_TABLE_MATCH_NETIF */ return (s16_t)i; } /** * 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 netif netif related to this entry (used for NETIF_ADDRHINT) * @param ipaddr IP address of the inserted ARP entry. * @param ethaddr Ethernet address of the inserted ARP entry. * @param flags See @ref etharp_state * * @return * - ERR_OK Successfully updated ARP cache. * - ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set. * - ERR_ARG Non-unicast address given, those will not appear in ARP cache. * * @see pbuf_free() */ static err_t etharp_update_arp_entry(struct netif *netif, const ip4_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags) { s16_t i; LWIP_ASSERT("netif->hwaddr_len == ETH_HWADDR_LEN", netif->hwaddr_len == ETH_HWADDR_LEN); LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_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_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr), (u16_t)ethaddr->addr[0], (u16_t)ethaddr->addr[1], (u16_t)ethaddr->addr[2], (u16_t)ethaddr->addr[3], (u16_t)ethaddr->addr[4], (u16_t)ethaddr->addr[5])); /* non-unicast address? */ if (ip4_addr_isany(ipaddr) || ip4_addr_isbroadcast(ipaddr, netif) || ip4_addr_ismulticast(ipaddr)) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: will not add non-unicast IP address to ARP cache\n")); return ERR_ARG; } /* find or create ARP entry */ i = etharp_find_entry(ipaddr, flags, netif); /* bail out if no entry could be found */ if (i < 0) { return (err_t)i; } #if ETHARP_SUPPORT_STATIC_ENTRIES if (flags & ETHARP_FLAG_STATIC_ENTRY) { /* record static type */ arp_table[i].state = ETHARP_STATE_STATIC; } else if (arp_table[i].state == ETHARP_STATE_STATIC) { /* found entry is a static type, don't overwrite it */ return ERR_VAL; } else #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ { /* mark it stable */ arp_table[i].state = ETHARP_STATE_STABLE; } /* record network interface */ arp_table[i].netif = netif; /* insert in SNMP ARP index tree */ mib2_add_arp_entry(netif, &arp_table[i].ipaddr); LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: updating stable entry %"S16_F"\n", i)); /* update address */ SMEMCPY(&arp_table[i].ethaddr, ethaddr, ETH_HWADDR_LEN); /* reset time stamp */ arp_table[i].ctime = 0; /* this is where we will send out queued packets! */ #if ARP_QUEUEING 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); #else /* ARP_QUEUEING */ if (arp_table[i].q != NULL) { struct pbuf *p = arp_table[i].q; arp_table[i].q = NULL; #endif /* ARP_QUEUEING */ /* send the queued IP packet */ ethernet_output(netif, p, (struct eth_addr *)(netif->hwaddr), ethaddr, ETHTYPE_IP); /* free the queued IP packet */ pbuf_free(p); } return ERR_OK; } #if ETHARP_SUPPORT_STATIC_ENTRIES /** Add a new static entry to the ARP table. If an entry exists for the * specified IP address, this entry is overwritten. * If packets are queued for the specified IP address, they are sent out. * * @param ipaddr IP address for the new static entry * @param ethaddr ethernet address for the new static entry * @return See return values of etharp_add_static_entry */ err_t etharp_add_static_entry(const ip4_addr_t *ipaddr, struct eth_addr *ethaddr) { struct netif *netif; LWIP_ASSERT_CORE_LOCKED(); LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_add_static_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_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr), (u16_t)ethaddr->addr[0], (u16_t)ethaddr->addr[1], (u16_t)ethaddr->addr[2], (u16_t)ethaddr->addr[3], (u16_t)ethaddr->addr[4], (u16_t)ethaddr->addr[5])); #ifdef LOSCFG_NET_CONTAINER netif = ip4_route(ipaddr, get_root_net_group()); #else netif = ip4_route(ipaddr); #endif if (netif == NULL) { return ERR_RTE; } return etharp_update_arp_entry(netif, ipaddr, ethaddr, ETHARP_FLAG_TRY_HARD | ETHARP_FLAG_STATIC_ENTRY); } /** Remove a static entry from the ARP table previously added with a call to * etharp_add_static_entry. * * @param ipaddr IP address of the static entry to remove * @return ERR_OK: entry removed * ERR_MEM: entry wasn't found * ERR_ARG: entry wasn't a static entry but a dynamic one */ err_t etharp_remove_static_entry(const ip4_addr_t *ipaddr) { s16_t i; LWIP_ASSERT_CORE_LOCKED(); LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n", ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr))); /* find or create ARP entry */ i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY, NULL); /* bail out if no entry could be found */ if (i < 0) { return (err_t)i; } if (arp_table[i].state != ETHARP_STATE_STATIC) { /* entry wasn't a static entry, cannot remove it */ return ERR_ARG; } /* entry found, free it */ etharp_free_entry(i); return ERR_OK; } #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */ /** * Remove all ARP table entries of the specified netif. * * @param netif points to a network interface */ void etharp_cleanup_netif(struct netif *netif) { int i; for (i = 0; i < ARP_TABLE_SIZE; ++i) { u8_t state = arp_table[i].state; if ((state != ETHARP_STATE_EMPTY) && (arp_table[i].netif == netif)) { etharp_free_entry(i); } } } /** * 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 */ ssize_t etharp_find_addr(struct netif *netif, const ip4_addr_t *ipaddr, struct eth_addr **eth_ret, const ip4_addr_t **ip_ret) { s16_t i; LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL", eth_ret != NULL && ip_ret != NULL); LWIP_UNUSED_ARG(netif); i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY, netif); 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; } /** * Possibility to iterate over stable ARP table entries * * @param i entry number, 0 to ARP_TABLE_SIZE * @param ipaddr return value: IP address * @param netif return value: points to interface * @param eth_ret return value: ETH address * @return 1 on valid index, 0 otherwise */ int etharp_get_entry(size_t i, ip4_addr_t **ipaddr, struct netif **netif, struct eth_addr **eth_ret) { LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL); LWIP_ASSERT("netif != NULL", netif != NULL); LWIP_ASSERT("eth_ret != NULL", eth_ret != NULL); if ((i < ARP_TABLE_SIZE) && (arp_table[i].state >= ETHARP_STATE_STABLE)) { *ipaddr = &arp_table[i].ipaddr; *netif = arp_table[i].netif; *eth_ret = &arp_table[i].ethaddr; return 1; } else { return 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 p The ARP packet that arrived on netif. Is freed by this function. * @param netif The lwIP network interface on which the ARP packet pbuf arrived. * * @see pbuf_free() */ void etharp_input(struct pbuf *p, struct netif *netif) { struct etharp_hdr *hdr; /* these are aligned properly, whereas the ARP header fields might not be */ ip4_addr_t sipaddr, dipaddr; u8_t for_us; LWIP_ASSERT_CORE_LOCKED(); LWIP_ERROR("netif != NULL", (netif != NULL), return;); hdr = (struct etharp_hdr *)p->payload; /* RFC 826 "Packet Reception": */ if ((hdr->hwtype != PP_HTONS(LWIP_IANA_HWTYPE_ETHERNET)) || (hdr->hwlen != ETH_HWADDR_LEN) || (hdr->protolen != sizeof(ip4_addr_t)) || (hdr->proto != PP_HTONS(ETHTYPE_IP))) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("etharp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n", hdr->hwtype, (u16_t)hdr->hwlen, hdr->proto, (u16_t)hdr->protolen)); 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 continuously 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 ip4_addr_wordaligned to aligned ip4_addr, to support compilers without * structure packing (not using structure copy which breaks strict-aliasing rules). */ IPADDR_WORDALIGNED_COPY_TO_IP4_ADDR_T(&sipaddr, &hdr->sipaddr); IPADDR_WORDALIGNED_COPY_TO_IP4_ADDR_T(&dipaddr, &hdr->dipaddr); /* this interface is not configured? */ if (ip4_addr_isany_val(*netif_ip4_addr(netif))) { for_us = 0; } else { /* ARP packet directed to us? */ for_us = (u8_t)ip4_addr_cmp(&dipaddr, netif_ip4_addr(netif)); } /* ARP message directed to 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. ARP message not directed to us? -> update the source IP address in the cache, if present */ etharp_update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY); /* now act on the message itself */ switch (hdr->opcode) { /* ARP request? */ case PP_HTONS(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 possibly send out an IP packet that was queued on it. */ LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: incoming ARP request\n")); /* ARP request for our address? */ if (for_us) { /* send ARP response */ etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &hdr->shwaddr, (struct eth_addr *)netif->hwaddr, netif_ip4_addr(netif), &hdr->shwaddr, &sipaddr, ARP_REPLY); /* we are not configured? */ } else if (ip4_addr_isany_val(*netif_ip4_addr(netif))) { /* { for_us == 0 and netif->ip_addr.addr == 0 } */ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_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_input: ARP request was not for us.\n")); } break; case PP_HTONS(ARP_REPLY): /* ARP reply. We already updated the ARP cache earlier. */ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_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 /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */ break; default: LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_input: ARP unknown opcode type %"S16_F"\n", lwip_htons(hdr->opcode))); ETHARP_STATS_INC(etharp.err); break; } /* free ARP packet */ pbuf_free(p); } /** Just a small helper function that sends a pbuf to an ethernet address * in the arp_table specified by the index 'arp_idx'. */ static err_t etharp_output_to_arp_index(struct netif *netif, struct pbuf *q, netif_addr_idx_t arp_idx) { LWIP_ASSERT("arp_table[arp_idx].state >= ETHARP_STATE_STABLE", arp_table[arp_idx].state >= ETHARP_STATE_STABLE); /* if arp table entry is about to expire: re-request it, but only if its state is ETHARP_STATE_STABLE to prevent flooding the network with ARP requests if this address is used frequently. */ if (arp_table[arp_idx].state == ETHARP_STATE_STABLE) { if (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED_BROADCAST) { /* issue a standard request using broadcast */ if (etharp_request(netif, &arp_table[arp_idx].ipaddr) == ERR_OK) { arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING_1; } } else if (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED_UNICAST) { /* issue a unicast request (for 15 seconds) to prevent unnecessary broadcast */ if (etharp_request_dst(netif, &arp_table[arp_idx].ipaddr, &arp_table[arp_idx].ethaddr) == ERR_OK) { arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING_1; } } } return ethernet_output(netif, q, (struct eth_addr *)(netif->hwaddr), &arp_table[arp_idx].ethaddr, ETHTYPE_IP); } /** * 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 ethernet_output(). */ err_t etharp_output(struct netif *netif, struct pbuf *q, const ip4_addr_t *ipaddr) { const struct eth_addr *dest; struct eth_addr mcastaddr; const ip4_addr_t *dst_addr = ipaddr; LWIP_ASSERT_CORE_LOCKED(); LWIP_ASSERT("netif != NULL", netif != NULL); LWIP_ASSERT("q != NULL", q != NULL); LWIP_ASSERT("ipaddr != NULL", ipaddr != 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 (ip4_addr_isbroadcast(ipaddr, netif)) { /* broadcast on Ethernet also */ dest = (const struct eth_addr *)ðbroadcast; /* multicast destination IP address? */ } else if (ip4_addr_ismulticast(ipaddr)) { /* Hash IP multicast address to MAC address.*/ mcastaddr.addr[0] = LL_IP4_MULTICAST_ADDR_0; mcastaddr.addr[1] = LL_IP4_MULTICAST_ADDR_1; mcastaddr.addr[2] = LL_IP4_MULTICAST_ADDR_2; 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 { netif_addr_idx_t i; /* outside local network? if so, this can neither be a global broadcast nor a subnet broadcast. */ if (!ip4_addr_netcmp(ipaddr, netif_ip4_addr(netif), netif_ip4_netmask(netif)) && !ip4_addr_islinklocal(ipaddr)) { #if LWIP_AUTOIP struct ip_hdr *iphdr = LWIP_ALIGNMENT_CAST(struct ip_hdr *, q->payload); /* According to RFC 3297, chapter 2.6.2 (Forwarding Rules), a packet with a link-local source address must always be "directly to its destination on the same physical link. The host MUST NOT send the packet to any router for forwarding". */ if (!ip4_addr_islinklocal(&iphdr->src)) #endif /* LWIP_AUTOIP */ { #ifdef LWIP_HOOK_ETHARP_GET_GW /* For advanced routing, a single default gateway might not be enough, so get the IP address of the gateway to handle the current destination address. */ dst_addr = LWIP_HOOK_ETHARP_GET_GW(netif, ipaddr); if (dst_addr == NULL) #endif /* LWIP_HOOK_ETHARP_GET_GW */ { /* interface has default gateway? */ if (!ip4_addr_isany_val(*netif_ip4_gw(netif))) { /* send to hardware address of default gateway IP address */ dst_addr = netif_ip4_gw(netif); /* no default gateway available */ } else { /* no route to destination error (default gateway missing) */ return ERR_RTE; } } } } #if LWIP_NETIF_HWADDRHINT if (netif->hints != NULL) { /* per-pcb cached entry was given */ netif_addr_idx_t etharp_cached_entry = netif->hints->addr_hint; if (etharp_cached_entry < ARP_TABLE_SIZE) { #endif /* LWIP_NETIF_HWADDRHINT */ if ((arp_table[etharp_cached_entry].state >= ETHARP_STATE_STABLE) && #if ETHARP_TABLE_MATCH_NETIF (arp_table[etharp_cached_entry].netif == netif) && #endif (ip4_addr_cmp(dst_addr, &arp_table[etharp_cached_entry].ipaddr))) { /* the per-pcb-cached entry is stable and the right one! */ ETHARP_STATS_INC(etharp.cachehit); return etharp_output_to_arp_index(netif, q, etharp_cached_entry); } #if LWIP_NETIF_HWADDRHINT } } #endif /* LWIP_NETIF_HWADDRHINT */ /* find stable entry: do this here since this is a critical path for throughput and etharp_find_entry() is kind of slow */ for (i = 0; i < ARP_TABLE_SIZE; i++) { if ((arp_table[i].state >= ETHARP_STATE_STABLE) && #if ETHARP_TABLE_MATCH_NETIF (arp_table[i].netif == netif) && #endif (ip4_addr_cmp(dst_addr, &arp_table[i].ipaddr))) { /* found an existing, stable entry */ ETHARP_SET_ADDRHINT(netif, i); return etharp_output_to_arp_index(netif, q, i); } } /* no stable entry found, use the (slower) query function: queue on destination Ethernet address belonging to ipaddr */ return etharp_query(netif, dst_addr, q); } /* continuation for multicast/broadcast destinations */ /* obtain source Ethernet address of the given interface */ /* send packet directly on the link */ return ethernet_output(netif, q, (struct eth_addr *)(netif->hwaddr), dest, ETHTYPE_IP); } /** * 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, const ip4_addr_t *ipaddr, struct pbuf *q) { struct eth_addr *srcaddr = (struct eth_addr *)netif->hwaddr; err_t result = ERR_MEM; int is_new_entry = 0; s16_t i_err; netif_addr_idx_t i; /* non-unicast address? */ if (ip4_addr_isbroadcast(ipaddr, netif) || ip4_addr_ismulticast(ipaddr) || ip4_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 */ i_err = etharp_find_entry(ipaddr, ETHARP_FLAG_TRY_HARD, netif); /* could not find or create entry? */ if (i_err < 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_err; } LWIP_ASSERT("type overflow", (size_t)i_err < NETIF_ADDR_IDX_MAX); i = (netif_addr_idx_t)i_err; /* mark a fresh entry as pending (we just sent a request) */ if (arp_table[i].state == ETHARP_STATE_EMPTY) { is_new_entry = 1; arp_table[i].state = ETHARP_STATE_PENDING; /* record network interface for re-sending arp request in etharp_tmr */ arp_table[i].netif = netif; } /* { 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 new entry? or an implicit query request? */ if (is_new_entry || (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. */ } else { /* ARP request successfully sent */ if ((arp_table[i].state == ETHARP_STATE_PENDING) && !is_new_entry) { /* A new ARP request has been sent for a pending entry. Reset the ctime to not let it expire too fast. */ LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: reset ctime for entry %"S16_F"\n", (s16_t)i)); arp_table[i].ctime = 0; } } if (q == NULL) { return result; } } /* packet given? */ LWIP_ASSERT("q != NULL", q != NULL); /* stable entry? */ if (arp_table[i].state >= ETHARP_STATE_STABLE) { /* we have a valid IP->Ethernet address mapping */ ETHARP_SET_ADDRHINT(netif, i); /* send the packet */ result = ethernet_output(netif, q, srcaddr, &(arp_table[i].ethaddr), ETHTYPE_IP); /* pending entry? (either just created or already pending */ } else if (arp_table[i].state == ETHARP_STATE_PENDING) { /* entry is still pending, queue the given packet 'q' */ struct pbuf *p; int copy_needed = 0; /* IF q includes a pbuf that must be copied, copy the whole chain into a * new PBUF_RAM. See the definition of PBUF_NEEDS_COPY for details. */ p = q; while (p) { LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0)); if (PBUF_NEEDS_COPY(p)) { copy_needed = 1; break; } p = p->next; } if (copy_needed) { /* copy the whole packet into new pbufs */ p = pbuf_clone(PBUF_LINK, PBUF_RAM, q); } else { /* referencing the old pbuf is enough */ p = q; pbuf_ref(p); } /* packet could be taken over? */ if (p != NULL) { /* queue packet ... */ #if ARP_QUEUEING struct etharp_q_entry *new_entry; /* allocate a new arp queue entry */ new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE); if (new_entry != NULL) { unsigned int qlen = 0; 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; qlen++; while (r->next != NULL) { r = r->next; qlen++; } r->next = new_entry; } else { /* queue did not exist, first item in queue */ arp_table[i].q = new_entry; } #if ARP_QUEUE_LEN if (qlen >= ARP_QUEUE_LEN) { struct etharp_q_entry *old; old = arp_table[i].q; arp_table[i].q = arp_table[i].q->next; pbuf_free(old->p); memp_free(MEMP_ARP_QUEUE, old); } #endif LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"U16_F"\n", (void *)q, 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; } #else /* ARP_QUEUEING */ /* always queue one packet per ARP request only, freeing a previously queued packet */ if (arp_table[i].q != NULL) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: dropped previously queued packet %p for ARP entry %"U16_F"\n", (void *)q, (u16_t)i)); pbuf_free(arp_table[i].q); } arp_table[i].q = p; result = ERR_OK; LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"U16_F"\n", (void *)q, (u16_t)i)); #endif /* ARP_QUEUEING */ } 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; } } 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 */ static 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 ip4_addr_t *ipsrc_addr, const struct eth_addr *hwdst_addr, const ip4_addr_t *ipdst_addr, const u16_t opcode) { struct pbuf *p; err_t result = ERR_OK; struct etharp_hdr *hdr; LWIP_ASSERT("netif != NULL", netif != NULL); /* allocate a pbuf for the outgoing ARP request packet */ p = pbuf_alloc(PBUF_LINK, SIZEOF_ETHARP_HDR, PBUF_RAM); /* could allocate a pbuf for an ARP request? */ if (p == NULL) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("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_ETHARP_HDR)); hdr = (struct etharp_hdr *)p->payload; LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n")); hdr->opcode = lwip_htons(opcode); LWIP_ASSERT("netif->hwaddr_len must be the same as ETH_HWADDR_LEN for etharp!", (netif->hwaddr_len == ETH_HWADDR_LEN)); /* Write the ARP MAC-Addresses */ SMEMCPY(&hdr->shwaddr, hwsrc_addr, ETH_HWADDR_LEN); SMEMCPY(&hdr->dhwaddr, hwdst_addr, ETH_HWADDR_LEN); /* Copy struct ip4_addr_wordaligned to aligned ip4_addr, to support compilers without * structure packing. */ IPADDR_WORDALIGNED_COPY_FROM_IP4_ADDR_T(&hdr->sipaddr, ipsrc_addr); IPADDR_WORDALIGNED_COPY_FROM_IP4_ADDR_T(&hdr->dipaddr, ipdst_addr); hdr->hwtype = PP_HTONS(LWIP_IANA_HWTYPE_ETHERNET); hdr->proto = PP_HTONS(ETHTYPE_IP); /* set hwlen and protolen */ hdr->hwlen = ETH_HWADDR_LEN; hdr->protolen = sizeof(ip4_addr_t); /* send ARP query */ #if LWIP_AUTOIP /* If we are using Link-Local, all ARP packets that contain a Link-Local * 'sender IP address' MUST be sent using link-layer broadcast instead of * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */ if (ip4_addr_islinklocal(ipsrc_addr)) { ethernet_output(netif, p, ethsrc_addr, ðbroadcast, ETHTYPE_ARP); } else #endif /* LWIP_AUTOIP */ { ethernet_output(netif, p, ethsrc_addr, ethdst_addr, ETHTYPE_ARP); } 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 to a specific eth address. * Used to send unicast request to refresh the ARP table just before an entry * times out * * @param netif the lwip network interface on which to send the request * @param ipaddr the IP address for which to ask * @param hw_dst_addr the ethernet address to send this packet to * @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 */ static err_t etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr *hw_dst_addr) { return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, hw_dst_addr, (struct eth_addr *)netif->hwaddr, netif_ip4_addr(netif), ðzero, ipaddr, ARP_REQUEST); } /** * 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, const ip4_addr_t *ipaddr) { LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n")); return etharp_request_dst(netif, ipaddr, ðbroadcast); } #endif /* LWIP_IPV4 && LWIP_ARP */