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fixed bug #33551 (ARP entries may time out although in use) by sending an ARP request when an ARP entry is used in the last minute before it would time out.

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Simon Goldschmidt 2011-07-21 20:28:18 +02:00 committed by goldsimon
parent 23dfcf7b8c
commit be412dc042
2 changed files with 112 additions and 61 deletions
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5
CHANGELOG
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@ -17,6 +17,11 @@ HISTORY
++ Bugfixes: ++ Bugfixes:
2011-07-21: Simon Goldschmidt
* etharp.c: fixed bug #33551 (ARP entries may time out although in use) by
sending an ARP request when an ARP entry is used in the last minute before
it would time out.
2011-07-04: Simon Goldschmidt 2011-07-04: Simon Goldschmidt
* sys_arch.txt: Fixed documentation after changing sys arch prototypes for 1.4.0. * sys_arch.txt: Fixed documentation after changing sys arch prototypes for 1.4.0.

168
src/netif/etharp.c
View File

@ -71,7 +71,11 @@ const struct eth_addr ethzero = {{0,0,0,0,0,0}};
* for ARP_TMR_INTERVAL = 5000, this is * for ARP_TMR_INTERVAL = 5000, this is
* (240 * 5) seconds = 20 minutes. * (240 * 5) seconds = 20 minutes.
*/ */
#define ARP_MAXAGE 240 #define ARP_MAXAGE 240
/** 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 (ARP_MAXAGE - 12)
/** the time an ARP entry stays pending after first request, /** the time an ARP entry stays pending after first request,
* for ARP_TMR_INTERVAL = 5000, this is * for ARP_TMR_INTERVAL = 5000, this is
* (2 * 5) seconds = 10 seconds. * (2 * 5) seconds = 10 seconds.
@ -86,7 +90,8 @@ const struct eth_addr ethzero = {{0,0,0,0,0,0}};
enum etharp_state { enum etharp_state {
ETHARP_STATE_EMPTY = 0, ETHARP_STATE_EMPTY = 0,
ETHARP_STATE_PENDING, ETHARP_STATE_PENDING,
ETHARP_STATE_STABLE ETHARP_STATE_STABLE,
ETHARP_STATE_STABLE_REREQUESTING
}; };
struct etharp_entry { struct etharp_entry {
@ -98,10 +103,8 @@ struct etharp_entry {
struct pbuf *q; struct pbuf *q;
#endif /* ARP_QUEUEING */ #endif /* ARP_QUEUEING */
ip_addr_t ipaddr; ip_addr_t ipaddr;
struct eth_addr ethaddr;
#if LWIP_SNMP
struct netif *netif; struct netif *netif;
#endif /* LWIP_SNMP */ struct eth_addr ethaddr;
u8_t state; u8_t state;
u8_t ctime; u8_t ctime;
#if ETHARP_SUPPORT_STATIC_ENTRIES #if ETHARP_SUPPORT_STATIC_ENTRIES
@ -185,9 +188,7 @@ free_entry(int i)
#ifdef LWIP_DEBUG #ifdef LWIP_DEBUG
/* for debugging, clean out the complete entry */ /* for debugging, clean out the complete entry */
arp_table[i].ctime = 0; arp_table[i].ctime = 0;
#if LWIP_SNMP
arp_table[i].netif = NULL; arp_table[i].netif = NULL;
#endif /* LWIP_SNMP */
ip_addr_set_zero(&arp_table[i].ipaddr); ip_addr_set_zero(&arp_table[i].ipaddr);
arp_table[i].ethaddr = ethzero; arp_table[i].ethaddr = ethzero;
#endif /* LWIP_DEBUG */ #endif /* LWIP_DEBUG */
@ -219,10 +220,16 @@ etharp_tmr(void)
(arp_table[i].ctime >= ARP_MAXPENDING))) { (arp_table[i].ctime >= ARP_MAXPENDING))) {
/* pending or stable entry has become old! */ /* pending or stable entry has become old! */
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n", LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i)); arp_table[i].state >= ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
/* clean up entries that have just been expired */ /* clean up entries that have just been expired */
free_entry(i); free_entry(i);
} }
else if ((arp_table[i].ctime >= ARP_AGE_REREQUEST_USED) &&
(arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING)) {
/* stable entry that is in use is about to expire: re-request it to
prevent it from breaking communication when it expires */
etharp_request(arp_table[i].netif, &arp_table[i].ipaddr);
}
#if ARP_QUEUEING #if ARP_QUEUEING
/* still pending entry? (not expired) */ /* still pending entry? (not expired) */
if (arp_table[i].state == ETHARP_STATE_PENDING) { if (arp_table[i].state == ETHARP_STATE_PENDING) {
@ -288,8 +295,8 @@ find_entry(ip_addr_t *ipaddr, u8_t flags)
/* remember first empty entry */ /* remember first empty entry */
empty = i; empty = i;
} else if (state != ETHARP_STATE_EMPTY) { } else if (state != ETHARP_STATE_EMPTY) {
LWIP_ASSERT("state == ETHARP_STATE_PENDING || state == ETHARP_STATE_STABLE", LWIP_ASSERT("state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE",
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 given, does IP address match IP address in ARP entry? */
if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) { if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching entry %"U16_F"\n", (u16_t)i)); LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching entry %"U16_F"\n", (u16_t)i));
@ -313,7 +320,7 @@ find_entry(ip_addr_t *ipaddr, u8_t flags)
} }
} }
/* stable entry? */ /* stable entry? */
} else if (state == ETHARP_STATE_STABLE) { } else if (state >= ETHARP_STATE_STABLE) {
#if ETHARP_SUPPORT_STATIC_ENTRIES #if ETHARP_SUPPORT_STATIC_ENTRIES
/* don't record old_stable for static entries since they never expire */ /* don't record old_stable for static entries since they never expire */
if (arp_table[i].static_entry == 0) if (arp_table[i].static_entry == 0)
@ -472,10 +479,8 @@ update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethadd
/* mark it stable */ /* mark it stable */
arp_table[i].state = ETHARP_STATE_STABLE; arp_table[i].state = ETHARP_STATE_STABLE;
#if LWIP_SNMP
/* record network interface */ /* record network interface */
arp_table[i].netif = netif; arp_table[i].netif = netif;
#endif /* LWIP_SNMP */
/* insert in SNMP ARP index tree */ /* insert in SNMP ARP index tree */
snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr); snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
@ -557,7 +562,7 @@ etharp_remove_static_entry(ip_addr_t *ipaddr)
return (err_t)i; return (err_t)i;
} }
if ((arp_table[i].state != ETHARP_STATE_STABLE) || if ((arp_table[i].state < ETHARP_STATE_STABLE) ||
(arp_table[i].static_entry == 0)) { (arp_table[i].static_entry == 0)) {
/* entry wasn't a static entry, cannot remove it */ /* entry wasn't a static entry, cannot remove it */
return ERR_ARG; return ERR_ARG;
@ -591,7 +596,7 @@ etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
LWIP_UNUSED_ARG(netif); LWIP_UNUSED_ARG(netif);
i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY); i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) { if((i >= 0) && (arp_table[i].state >= ETHARP_STATE_STABLE)) {
*eth_ret = &arp_table[i].ethaddr; *eth_ret = &arp_table[i].ethaddr;
*ip_ret = &arp_table[i].ipaddr; *ip_ret = &arp_table[i].ipaddr;
return i; return i;
@ -815,6 +820,28 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
pbuf_free(p); 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, u8_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) &&
(arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED)) {
if (etharp_request(netif, &arp_table[arp_idx].ipaddr) == ERR_OK) {
arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING;
}
}
return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr),
&arp_table[arp_idx].ethaddr);
}
/** /**
* Resolve and fill-in Ethernet address header for outgoing IP packet. * Resolve and fill-in Ethernet address header for outgoing IP packet.
* *
@ -836,7 +863,13 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
err_t err_t
etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr) etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
{ {
struct eth_addr *dest, mcastaddr; struct eth_addr *dest;
struct eth_addr mcastaddr;
ip_addr_t *dst_addr = ipaddr;
LWIP_ASSERT("netif != NULL", netif != NULL);
LWIP_ASSERT("q != NULL", q != NULL);
LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL);
/* make room for Ethernet header - should not fail */ /* make room for Ethernet header - should not fail */
if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) { if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
@ -847,8 +880,48 @@ etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
return ERR_BUF; return ERR_BUF;
} }
/* assume unresolved Ethernet address */ /* outside local network? if so, this can neither be a global broadcast nor
dest = NULL; a subnet broadcast. */
if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask)) &&
!ip_addr_islinklocal(ipaddr)) {
#if LWIP_AUTOIP
struct ip_hdr *iphdr = (struct ip_hdr*)((u8_t*)q->payload +
sizeof(struct eth_hdr));
/* 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 (!ip_addr_islinklocal(&iphdr->src))
#endif /* LWIP_AUTOIP */
{
/* interface has default gateway? */
if (!ip_addr_isany(&netif->gw)) {
/* send to hardware address of default gateway IP address */
dst_addr = &(netif->gw);
/* no default gateway available */
} else {
/* no route to destination error (default gateway missing) */
return ERR_RTE;
}
}
}
#if LWIP_NETIF_HWADDRHINT
if (netif->addr_hint != NULL) {
/* per-pcb cached entry was given */
u8_t etharp_cached_entry = *(netif->addr_hint);
if (etharp_cached_entry < ARP_TABLE_SIZE) {
#endif /* LWIP_NETIF_HWADDRHINT */
if ((arp_table[etharp_cached_entry].state >= ETHARP_STATE_STABLE) &&
(ip_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 */
/* Determine on destination hardware address. Broadcasts and multicasts /* Determine on destination hardware address. Broadcasts and multicasts
* are special, other IP addresses are looked up in the ARP table. */ * are special, other IP addresses are looked up in the ARP table. */
@ -869,49 +942,20 @@ etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
dest = &mcastaddr; dest = &mcastaddr;
/* unicast destination IP address? */ /* unicast destination IP address? */
} else { } else {
/* outside local network? */ s8_t i;
if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask)) && /* find stable entry: do this here since this is a critical path for
!ip_addr_islinklocal(ipaddr)) { throughput and find_entry() is kind of slow */
#if LWIP_AUTOIP for (i = 0; i < ARP_TABLE_SIZE; i++) {
struct ip_hdr *iphdr = (struct ip_hdr*)((u8_t*)q->payload + if ((arp_table[i].state >= ETHARP_STATE_STABLE) &&
sizeof(struct eth_hdr)); (ip_addr_cmp(dst_addr, &arp_table[i].ipaddr))) {
/* According to RFC 3297, chapter 2.6.2 (Forwarding Rules), a packet with /* found an existing, stable entry */
a link-local source address must always be "directly to its destination ETHARP_SET_HINT(netif, i);
on the same physical link. The host MUST NOT send the packet to any return etharp_output_to_arp_index(netif, q, i);
router for forwarding". */
if (!ip_addr_islinklocal(&iphdr->src))
#endif /* LWIP_AUTOIP */
{
/* interface has default gateway? */
if (!ip_addr_isany(&netif->gw)) {
/* send to hardware address of default gateway IP address */
ipaddr = &(netif->gw);
/* no default gateway available */
} else {
/* no route to destination error (default gateway missing) */
return ERR_RTE;
}
} }
} }
#if LWIP_NETIF_HWADDRHINT /* no stable entry found, use the (slower) query function:
if (netif->addr_hint != NULL) { queue on destination Ethernet address belonging to ipaddr */
/* per-pcb cached entry was given */ return etharp_query(netif, dst_addr, q);
u8_t etharp_cached_entry = *(netif->addr_hint);
if (etharp_cached_entry < ARP_TABLE_SIZE) {
#endif /* LWIP_NETIF_HWADDRHINT */
if ((arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) &&
(ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr))) {
/* the per-pcb-cached entry is stable and the right one! */
ETHARP_STATS_INC(etharp.cachehit);
return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr),
&arp_table[etharp_cached_entry].ethaddr);
}
#if LWIP_NETIF_HWADDRHINT
}
}
#endif /* LWIP_NETIF_HWADDRHINT */
/* queue on destination Ethernet address belonging to ipaddr */
return etharp_query(netif, ipaddr, q);
} }
/* continuation for multicast/broadcast destinations */ /* continuation for multicast/broadcast destinations */
@ -989,7 +1033,7 @@ etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
/* { i is either a STABLE or (new or existing) PENDING entry } */ /* { i is either a STABLE or (new or existing) PENDING entry } */
LWIP_ASSERT("arp_table[i].state == PENDING or STABLE", LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
((arp_table[i].state == ETHARP_STATE_PENDING) || ((arp_table[i].state == ETHARP_STATE_PENDING) ||
(arp_table[i].state == ETHARP_STATE_STABLE))); (arp_table[i].state >= ETHARP_STATE_STABLE)));
/* do we have a pending entry? or an implicit query request? */ /* do we have a pending entry? or an implicit query request? */
if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) { if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
@ -1009,7 +1053,7 @@ etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
/* packet given? */ /* packet given? */
LWIP_ASSERT("q != NULL", q != NULL); LWIP_ASSERT("q != NULL", q != NULL);
/* stable entry? */ /* stable entry? */
if (arp_table[i].state == ETHARP_STATE_STABLE) { if (arp_table[i].state >= ETHARP_STATE_STABLE) {
/* we have a valid IP->Ethernet address mapping */ /* we have a valid IP->Ethernet address mapping */
ETHARP_SET_HINT(netif, i); ETHARP_SET_HINT(netif, i);
/* send the packet */ /* send the packet */
@ -1127,6 +1171,8 @@ etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
const u8_t * ethdst_hwaddr; const u8_t * ethdst_hwaddr;
#endif /* LWIP_AUTOIP */ #endif /* LWIP_AUTOIP */
LWIP_ASSERT("netif != NULL", netif != NULL);
/* allocate a pbuf for the outgoing ARP request packet */ /* allocate a pbuf for the outgoing ARP request packet */
p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM); p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
/* could allocate a pbuf for an ARP request? */ /* could allocate a pbuf for an ARP request? */