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Added and clearified comment for upcoming code refactoring.

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This commit is contained in:
likewise 2003-11-14 19:23:08 +00:00
parent 5c9aa074eb
commit c13adc3616
1 changed files with 35 additions and 22 deletions
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57
src/netif/etharp.c
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@ -113,6 +113,9 @@ struct etharp_entry {
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;
#endif
u8_t ctime;
@ -155,16 +158,22 @@ etharp_tmr(void)
/* remove expired entries from the ARP table */
for (i = 0; i < ARP_TABLE_SIZE; ++i) {
arp_table[i].ctime++;
/* a resolved/stable entry? */
if ((arp_table[i].state == ETHARP_STATE_STABLE) &&
/* entry has become old? */
(arp_table[i].ctime >= ARP_MAXAGE)) {
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired stable entry %u.\n", i));
goto empty;
/* an unresolved/pending entry? */
} else if ((arp_table[i].state == ETHARP_STATE_PENDING) &&
/* entry unresolved/pending for too long? */
(arp_table[i].ctime >= ARP_MAXPENDING)) {
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired pending entry %u.\n", i));
empty:
empty:
/* empty old entry */
arp_table[i].state = ETHARP_STATE_EMPTY;
#if ARP_QUEUEING
/* and empty packet queue */
if (arp_table[i].p != NULL) {
/* remove any queued packet */
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %u, packet queue %p.\n", i, (void *)(arp_table[i].p)));
@ -197,12 +206,12 @@ find_arp_entry(void)
}
/* If no unused entry is found, we try to find the oldest entry and
throw it away. If all entries are new and have 0 ctime drop one */
throw it away. If all entries are new and ctime drop one */
if (i == ARP_TABLE_SIZE) {
maxtime = 0;
j = ARP_TABLE_SIZE;
for (i = 0; i < ARP_TABLE_SIZE; ++i) {
/* remember entry with oldest stable entry in j*/
/* remember entry with oldest stable entry in j */
if ((arp_table[i].state == ETHARP_STATE_STABLE) &&
#if ARP_QUEUEING /* do not want to re-use an entry with queued packets */
(arp_table[i].p == NULL) &&
@ -210,6 +219,7 @@ find_arp_entry(void)
(arp_table[i].ctime >= maxtime)) {
maxtime = arp_table[i].ctime;
j = i;
/* { j = oldest stable entry } */
}
}
if (j != ARP_TABLE_SIZE) {
@ -512,10 +522,10 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
* This ARP request is returned as a pbuf, which should be sent by
* the caller.
*
* If ARP failed to allocate resources, NULL is returned.
*
* A returned non-NULL packet should be sent by the caller.
*
* If ARP failed to allocate resources, NULL is returned.
*
* @param netif The lwIP network interface which the IP packet will be sent on.
* @param ipaddr The IP address of the packet destination.
* @param pbuf The pbuf(s) containing the IP packet to be sent.
@ -530,7 +540,7 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
struct eth_hdr *ethhdr;
u8_t i;
/* Make room for Ethernet header. */
/* make room for Ethernet header */
if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
/* The pbuf_header() call shouldn't fail, and we'll just bail
out if it does.. */
@ -539,9 +549,6 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
return NULL;
}
/* obtain source Ethernet address of the given interface */
srcaddr = (struct eth_addr *)netif->hwaddr;
/* assume unresolved Ethernet address */
dest = NULL;
/* Construct Ethernet header. Start with looking up deciding which
@ -569,19 +576,20 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
}
/* destination IP address is an IP unicast address */
else {
/* destination IP network address not on local network? */
/* this occurs if the packet is routed to the default gateway on this interface */
/* destination IP network address not on local network?
* IP layer wants us to forward to the default gateway */
if (!ip_addr_maskcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
/* gateway available? */
/* interface has default gateway? */
if (netif->gw.addr != 0)
{
/* use the gateway IP address */
/* route to default gateway IP address */
ipaddr = &(netif->gw);
}
/* no gateway available? */
else
{
/* IP destination address outside local network, but no gateway available */
/* { packet is discarded } */
return NULL;
}
}
@ -600,6 +608,7 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
/* ARP query for the IP address, submit this IP packet for queueing */
/* TODO: How do we handle netif->ipaddr == ipaddr? */
etharp_query(netif, ipaddr, q);
/* { packet was queued (ERR_OK), or discarded } */
/* return nothing */
return NULL;
}
@ -612,8 +621,11 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
/* destination Ethernet address known */
if (dest != NULL) {
/* A valid IP->MAC address mapping was found, so we construct the
Ethernet header for the outgoing packet. */
/* obtain source Ethernet address of the given interface */
srcaddr = (struct eth_addr *)netif->hwaddr;
/* A valid IP->MAC address mapping was found, fill in the
* Ethernet header for the outgoing packet */
ethhdr = q->payload;
for(i = 0; i < netif->hwaddr_len; i++) {
@ -654,7 +666,6 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
{
struct eth_addr *srcaddr;
struct etharp_hdr *hdr;
struct pbuf *p;
err_t result = ERR_OK;
u8_t i;
u8_t perform_arp_request = 1;
@ -683,11 +694,11 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
/* queried address not yet in ARP table? */
if (i == ARP_TABLE_SIZE) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: IP address not found in ARP table\n"));
/* find an available entry */
/* find an available (unused or old) entry */
i = find_arp_entry();
/* bail out if no ARP entries are available */
if (i == ARP_TABLE_SIZE) {
LWIP_DEBUGF(ETHARP_DEBUG | 2, ("etharp_query: no more ARP entries available.\n"));
LWIP_DEBUGF(ETHARP_DEBUG | 2, ("etharp_query: no more ARP entries available. Should seldom occur.\n"));
return ERR_MEM;
}
/* we will now recycle entry i */
@ -696,12 +707,13 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
ip_addr_set(&arp_table[i].ipaddr, ipaddr);
arp_table[i].ctime = 0;
arp_table[i].state = ETHARP_STATE_PENDING;
#if ARP_QUEUEING
/* free queued packet, as entry is now invalidated */
#if ARP_QUEUEING /* deal with queue of recycled entry */
/* free queued packet, as entry is now invalidated and recycled */
if (arp_table[i].p != NULL) {
pbuf_free(arp_table[i].p);
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3,
("etharp_query: dropped packet %p from recycled ARP entry queue. Should not occur.\n", (void *)arp_table[i].p));
arp_table[i].p = NULL;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("etharp_query: dropped packet on ARP queue. Should not occur.\n"));
}
#endif
}
@ -713,8 +725,8 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
/* earlier queued packet on this entry? */
if (arp_table[i].p != NULL) {
pbuf_free(arp_table[i].p);
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("etharp_query: dropped packet %p on ARP queue. Should not occur.\n", (void *)arp_table[i].p));
arp_table[i].p = NULL;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("etharp_query: dropped packet on ARP queue. Should not occur.\n"));
/* fall-through into next if */
}
#endif
@ -733,6 +745,7 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
/* ARP request? */
if (perform_arp_request)
{
struct pbuf *p;
/* allocate a pbuf for the outgoing ARP request packet */
p = pbuf_alloc(PBUF_LINK, sizeof(struct etharp_hdr), PBUF_RAM);
/* could allocate pbuf? */