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Prevent non-unicast addresses from polluting the ARP cache.

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This commit is contained in:
likewise 2004-05-05 23:47:33 +00:00
parent e2bc8e86e2
commit 273612b251
2 changed files with 33 additions and 22 deletions
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2
src/include/netif/etharp.h
View File

@ -49,6 +49,8 @@ struct eth_addr {
};
struct eth_hdr {
/* Ethernet header is 14 bytes, this breaks natural alignment on
* subsequent (TCP/IP) protocol header fields. */
#if ETH_PAD_SIZE
u8_t padding[ETH_PAD_SIZE];
#endif

53
src/netif/etharp.c
View File

@ -79,20 +79,20 @@ enum etharp_state {
ETHARP_STATE_EMPTY,
ETHARP_STATE_PENDING,
ETHARP_STATE_STABLE,
/** @internal convenience transitional state used in etharp_tmr() */
/** @internal transitional state used in etharp_tmr() for convenience*/
ETHARP_STATE_EXPIRED
};
struct etharp_entry {
struct ip_addr ipaddr;
struct eth_addr ethaddr;
enum etharp_state state;
#if ARP_QUEUEING
/**
* Pointer to queue of pending outgoing packets on this ARP entry.
* Must be at most a single packet for now. */
struct pbuf *p;
*/
struct pbuf *p;
#endif
struct ip_addr ipaddr;
struct eth_addr ethaddr;
enum etharp_state state;
u8_t ctime;
};
@ -233,12 +233,14 @@ find_arp_entry(void)
* - ARP_INSERT_FLAG Allows ARP to insert this as a new item. If not specified,
* only existing ARP entries will be updated.
*
* @return pbuf If non-NULL, a packet that was queued on a pending entry.
* You should sent it and must call pbuf_free() afterwards.
* @return
* - ERR_OK Succesfully updated ARP cache.
* - ERR_MEM If we could not add a new ARP entry when ARP_INSERT_FLAG was set.
* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
*
* @see pbuf_free()
*/
static struct pbuf *
err_t
update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
{
s8_t i, k;
@ -248,10 +250,12 @@ update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *e
ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr),
ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
/* do not update for 0.0.0.0 addresses */
if (ipaddr->addr == 0) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add 0.0.0.0 to ARP cache\n"));
return NULL;
/* non-unicast address? */
if (ip_addr_isany(ipaddr) ||
ip_addr_isbroadcast(ipaddr, netif) ||
ip_addr_ismulticast(ipaddr)) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
return ERR_ARG;
}
/* Walk through the ARP mapping table and try to find an entry to update.
* If none is found, a new IP -> MAC address mapping is inserted. */
@ -300,7 +304,7 @@ update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *e
}
#endif
/* IP addresses should only occur once in the ARP entry, we are done */
return NULL;
return ERR_OK;
}
} /* if STABLE */
} /* for all ARP entries */
@ -315,9 +319,9 @@ update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *e
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: adding entry to table\n"));
/* find an empty or old entry. */
i = find_arp_entry();
if (i == ERR_MEM) {
if (i < 0) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: no available entry found\n"));
return NULL;
return (err_t)i;
}
/* set IP address */
ip_addr_set(&arp_table[i].ipaddr, ipaddr);
@ -610,10 +614,11 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
* If the IP address was already stable in the cache, the packet is
* directly sent. An ARP request is sent out.
*
* @param netif The lwIP network interface where ipaddr
* @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.
*
* @return
* - ERR_BUF Could not make room for Ethernet header.
@ -621,12 +626,8 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
* 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).
*
* @note Might be used in the future by manual IP configuration
* as well.
* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
*
* TODO: use the ctime field to see how long ago an ARP request was sent,
* possibly retry.
*/
err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
{
@ -636,6 +637,14 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
s8_t i; /* ARP entry index */
u8_t k; /* Ethernet address octet index */
/* non-unicast address? */
if (ip_addr_isany(ipaddr) ||
ip_addr_isbroadcast(ipaddr, netif) ||
ip_addr_ismulticast(ipaddr)) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
return ERR_ARG;
}
/* Do three things in this order (by design):
*
* 1) send out ARP request