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/**
* @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 */
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