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Implemented conditional insertion of ARP entries to update_arp_entry using ARP_INSERT_FLAG.

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likewise 2002-11-13 08:56:11 +00:00
parent 1f1e6eb5a1
commit f9129c4dcd
1 changed files with 78 additions and 35 deletions
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113
src/netif/etharp.c
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@ -3,6 +3,9 @@
* Address Resolution Protocol module for IP over Ethernet
*
* $Log: etharp.c,v $
* Revision 1.7 2002/11/13 08:56:11 likewise
* Implemented conditional insertion of ARP entries to update_arp_entry using ARP_INSERT_FLAG.
*
* Revision 1.6 2002/11/11 14:34:29 likewise
* Changed static etharp_query() to support queueing packets. This fix missed in last commit.
*
@ -53,6 +56,38 @@
* Author: Adam Dunkels <adam@sics.se>
*
*/
/*
* TODO:
*
RFC 3220 4.6 IP Mobility Support for IPv4 January 2002
- A Gratuitous ARP [45] is an ARP packet sent by a node in order
to spontaneously cause other nodes to update an entry in their
ARP cache. A gratuitous ARP MAY use either an ARP Request or
an ARP Reply packet. In either case, the ARP Sender Protocol
Address and ARP Target Protocol Address are both set to the IP
address of the cache entry to be updated, and the ARP Sender
Hardware Address is set to the link-layer address to which this
cache entry should be updated. When using an ARP Reply packet,
the Target Hardware Address is also set to the link-layer
address to which this cache entry should be updated (this field
is not used in an ARP Request packet).
In either case, for a gratuitous ARP, the ARP packet MUST be
transmitted as a local broadcast packet on the local link. As
specified in [36], any node receiving any ARP packet (Request
or Reply) MUST update its local ARP cache with the Sender
Protocol and Hardware Addresses in the ARP packet, if the
receiving node has an entry for that IP address already in its
ARP cache. This requirement in the ARP protocol applies even
for ARP Request packets, and for ARP Reply packets that do not
match any ARP Request transmitted by the receiving node [36].
*
My suggestion would be to send a ARP request for our newly obtained
address upon configuration of an Ethernet interface.
*/
#include "lwip/opt.h"
#include "lwip/debug.h"
@ -67,10 +102,10 @@
# include "lwip/dhcp.h"
#endif
/** the time an ARP entry stays valid after its last update */
#define ARP_MAXAGE 120 /* 120 * 10 seconds = 20 minutes. */
/** the maximum time waiting for ARP reply to a ARP request */
#define ARP_MAXPENDING 2 /* 2 * 10 seconds = 20 seconds. */
/** the time an ARP entry stays valid after its last update, (120 * 10) seconds = 20 minutes. */
#define ARP_MAXAGE 120
/** the time an ARP entry stays pending after first request, (2 * 10) seconds = 20 seconds. */
#define ARP_MAXPENDING 2
#define HWTYPE_ETHERNET 1
@ -138,7 +173,8 @@ static const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
static struct etharp_entry arp_table[ARP_TABLE_SIZE];
static u8_t ctime;
static struct pbuf *insert_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr);
static struct pbuf *update_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags);
#define ARP_INSERT_FLAG 1
/**
* Initializes ARP module.
@ -151,6 +187,7 @@ etharp_init(void)
for(i = 0; i < ARP_TABLE_SIZE; ++i) {
arp_table[i].state = ETHARP_STATE_EMPTY;
}
/* reset ARP current time */
ctime = 0;
}
@ -223,18 +260,20 @@ find_arp_entry(void)
}
/**
* Insert an entry into the ARP cache, or update an existing one.
* Update (or insert) an entry in the ARP cache.
*
* @param ipaddr IP address of the inserted ARP entry.
* @param ethaddr Ethernet address of the inserted ARP entry.
*
* @param flags Defines behaviour:
* - 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().
*
* @see pbuf_free()
*/
static struct pbuf *
insert_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr)
update_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
{
u8_t i, k;
struct pbuf *p;
@ -250,7 +289,7 @@ insert_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr)
/* check those entries that are already in use. */
if(arp_table[i].state == ETHARP_STATE_STABLE) {
DEBUGF(ETHARP_DEBUG, ("insert_arp_entry: updating stable entry %u\n", i));
DEBUGF(ETHARP_DEBUG, ("update_arp_entry: updating stable entry %u\n", i));
/* An old entry found, update this and return. */
for(k = 0; k < 6; ++k) {
arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
@ -260,8 +299,8 @@ insert_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr)
}
else if(arp_table[i].state == ETHARP_STATE_PENDING) {
/* A pending entry was found, so we fill this in and return
the queued packet (if any). */
DEBUGF(ETHARP_DEBUG, ("insert_arp_entry: pending entry %u made stable\n", i));
the queued packet (if any). */
DEBUGF(ETHARP_DEBUG, ("update_arp_entry: pending entry %u made stable\n", i));
for(k = 0; k < 6; ++k) {
arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
}
@ -281,34 +320,38 @@ insert_arp_entry(struct ip_addr *ipaddr, struct eth_addr *ethaddr)
}
ethhdr->type = htons(ETHTYPE_IP);
DEBUGF(ETHARP_DEBUG, ("insert_arp_entry: returning queued packet %p\n", p));
DEBUGF(ETHARP_DEBUG, ("update_arp_entry: returning queued packet %p\n", p));
}
/* return queued packet, if any */
return p;
}
}
}
/* no matching ARP entry was found. find an empty or old entry. */
i = find_arp_entry();
if(i == ARP_TABLE_SIZE) {
DEBUGF(ETHARP_DEBUG, ("insert_arp_entry: no available entry found\n"));
return NULL;
}
/* no matching ARP entry was found */
/* allowed to insert an entry? */
if (flags & ARP_INSERT_FLAG)
{
/* find an empty or old entry. */
i = find_arp_entry();
if(i == ARP_TABLE_SIZE) {
DEBUGF(ETHARP_DEBUG, ("update_arp_entry: no available entry found\n"));
return NULL;
}
if (arp_table[i].state == ETHARP_STATE_STABLE) {
DEBUGF(ETHARP_DEBUG, ("insert_arp_entry: overwriting old stable entry %u\n", i));
if (arp_table[i].state == ETHARP_STATE_STABLE) {
DEBUGF(ETHARP_DEBUG, ("update_arp_entry: overwriting old stable entry %u\n", i));
}
else {
DEBUGF(ETHARP_DEBUG, ("update_arp_entry: using empty entry %u\n", i));
}
ip_addr_set(&arp_table[i].ipaddr, ipaddr);
for(k = 0; k < 6; ++k) {
arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
}
arp_table[i].ctime = ctime;
arp_table[i].state = ETHARP_STATE_STABLE;
arp_table[i].p = NULL;
}
else {
DEBUGF(ETHARP_DEBUG, ("insert_arp_entry: using empty entry %u\n", i));
}
ip_addr_set(&arp_table[i].ipaddr, ipaddr);
for(k = 0; k < 6; ++k) {
arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
}
arp_table[i].ctime = ctime;
arp_table[i].state = ETHARP_STATE_STABLE;
arp_table[i].p = NULL;
return NULL;
}
@ -346,8 +389,8 @@ etharp_ip_input(struct netif *netif, struct pbuf *p)
return NULL;
}
DEBUGF(ETHARP_DEBUG, ("etharp_ip_input: updating ETHARP table.\n"));
/* update ARP table */
return insert_arp_entry(&(hdr->ip.src), &(hdr->eth.src));
/* update ARP table, may insert */
return update_arp_entry(&(hdr->ip.src), &(hdr->eth.src), ARP_INSERT_FLAG);
}
@ -432,9 +475,9 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
if(ip_addr_cmp(&(hdr->dipaddr), &(netif->ip_addr))) {
struct pbuf *q;
DEBUGF(ETHARP_DEBUG, ("etharp_arp_input: ARP reply for us\n"));
/* insert_arp_entry() can return a pbuf that has previously been
/* update_arp_entry() can return a pbuf that has previously been
queued waiting for this IP address to become ARP stable. */
q = insert_arp_entry(&(hdr->sipaddr), &(hdr->shwaddr));
q = update_arp_entry(&(hdr->sipaddr), &(hdr->shwaddr), ARP_INSERT_FLAG);
/* free incoming ARP reply pbuf */
pbuf_free(p);
p = NULL;