diff options
Diffstat (limited to 'lwip/src/core/ipv4/etharp.c')
| -rw-r--r-- | lwip/src/core/ipv4/etharp.c | 1204 |
1 files changed, 1204 insertions, 0 deletions
diff --git a/lwip/src/core/ipv4/etharp.c b/lwip/src/core/ipv4/etharp.c new file mode 100644 index 0000000..442aac0 --- /dev/null +++ b/lwip/src/core/ipv4/etharp.c @@ -0,0 +1,1204 @@ +/** + * @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 <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_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 <string.h> + +#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 */ +} + +/** + * 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])); + + netif = ip4_route(ipaddr); + 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. */ + } + 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 */ |