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EBIKE-FreeRTOS/Common/ethernet/lwIP/netif/etharp.c
aixiao af0dfbbbb8 init
2024-04-14 18:38:39 +08:00

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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_query(our_netif, its_ip_addr, NULL) 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 <string.h>
#include "lwip/opt.h"
#include "lwip/inet.h"
#include "netif/etharp.h"
#include "lwip/ip.h"
#include "lwip/stats.h"
#include "lwip/snmp.h"
/* ARP needs to inform DHCP of any ARP replies? */
#if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
# include "lwip/dhcp.h"
#endif
/** the time an ARP entry stays valid after its last update,
* (240 * 5) seconds = 20 minutes.
*/
#define ARP_MAXAGE 240
/** the time an ARP entry stays pending after first request,
* (2 * 5) seconds = 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 2
#define HWTYPE_ETHERNET 1
/** ARP message types */
#define ARP_REQUEST 1
#define ARP_REPLY 2
#define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8)
#define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff)
#define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8))
#define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8))
enum etharp_state {
ETHARP_STATE_EMPTY,
ETHARP_STATE_PENDING,
ETHARP_STATE_STABLE,
/** @internal transitional state used in etharp_tmr() for convenience*/
ETHARP_STATE_EXPIRED
};
struct etharp_entry {
#if ARP_QUEUEING
/**
* Pointer to queue of pending outgoing packets on this ARP entry.
*/
struct pbuf *p;
#endif
struct ip_addr ipaddr;
struct eth_addr ethaddr;
enum etharp_state state;
u8_t ctime;
struct netif *netif;
};
static const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
static struct etharp_entry arp_table[ARP_TABLE_SIZE];
/**
* 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_TRY_HARD 1
static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags);
static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags);
/**
* Initializes ARP module.
*/
void
etharp_init(void)
{
u8_t i;
/* clear ARP entries */
for(i = 0; i < ARP_TABLE_SIZE; ++i) {
arp_table[i].state = ETHARP_STATE_EMPTY;
#if ARP_QUEUEING
arp_table[i].p = NULL;
#endif
arp_table[i].ctime = 0;
arp_table[i].netif = NULL;
}
}
/**
* Clears expired entries in the ARP table.
*
* This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
* in order to expire entries in the ARP table.
*/
void
etharp_tmr(void)
{
u8_t i;
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
/* remove expired entries from the ARP table */
for (i = 0; i < ARP_TABLE_SIZE; ++i) {
arp_table[i].ctime++;
/* 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 %"U16_F".\n", (u16_t)i));
arp_table[i].state = ETHARP_STATE_EXPIRED;
/* pending entry? */
} else if (arp_table[i].state == ETHARP_STATE_PENDING) {
/* entry unresolved/pending for too long? */
if (arp_table[i].ctime >= ARP_MAXPENDING) {
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired pending entry %"U16_F".\n", (u16_t)i));
arp_table[i].state = ETHARP_STATE_EXPIRED;
#if ARP_QUEUEING
} else if (arp_table[i].p != NULL) {
/* resend an ARP query here */
#endif
}
}
/* clean up entries that have just been expired */
if (arp_table[i].state == ETHARP_STATE_EXPIRED) {
/* remove from SNMP ARP index tree */
snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
#if ARP_QUEUEING
/* and empty packet queue */
if (arp_table[i].p != NULL) {
/* remove all queued packets */
LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].p)));
pbuf_free(arp_table[i].p);
arp_table[i].p = NULL;
}
#endif
/* recycle entry for re-use */
arp_table[i].state = ETHARP_STATE_EMPTY;
}
}
}
/**
* 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_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
* - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of
* active (stable or pending) entries.
*
* @return The ARP entry index that matched or is created, ERR_MEM if no
* entry is found or could be recycled.
*/
static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags)
{
s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
s8_t empty = ARP_TABLE_SIZE;
u8_t i = 0, age_pending = 0, age_stable = 0;
#if ARP_QUEUEING
/* oldest entry with packets on queue */
s8_t old_queue = ARP_TABLE_SIZE;
/* its age */
u8_t age_queue = 0;
#endif
/**
* 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) {
/* no empty entry found yet and now we do find one? */
if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) {
LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
/* remember first empty entry */
empty = i;
}
/* pending entry? */
else if (arp_table[i].state == ETHARP_STATE_PENDING) {
/* if given, does IP address match IP address in ARP entry? */
if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
/* found exact IP address match, simply bail out */
return i;
#if ARP_QUEUEING
/* pending with queued packets? */
} else if (arp_table[i].p != NULL) {
if (arp_table[i].ctime >= age_queue) {
old_queue = i;
age_queue = arp_table[i].ctime;
}
#endif
/* pending without queued packets? */
} else {
if (arp_table[i].ctime >= age_pending) {
old_pending = i;
age_pending = arp_table[i].ctime;
}
}
}
/* stable entry? */
else if (arp_table[i].state == ETHARP_STATE_STABLE) {
/* if given, does IP address match IP address in ARP entry? */
if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
/* found exact IP address match, simply bail out */
return i;
/* remember entry with oldest stable entry in oldest, its age in maxtime */
} else 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 */
/* no empty entry found and not allowed to recycle? */
if ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0))
{
return (s8_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 without queued packets
*
* { ETHARP_TRY_HARD is set at this point }
*/
/* 1) empty entry available? */
if (empty < ARP_TABLE_SIZE) {
i = empty;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
}
/* 2) found recyclable stable entry? */
else if (old_stable < ARP_TABLE_SIZE) {
/* recycle oldest stable*/
i = old_stable;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
#if ARP_QUEUEING
/* no queued packets should exist on stable entries */
LWIP_ASSERT("arp_table[i].p == NULL", arp_table[i].p == NULL);
#endif
/* 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 | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
#if ARP_QUEUEING
/* 4) found recyclable pending entry with queued packets? */
} else if (old_queue < ARP_TABLE_SIZE) {
/* recycle oldest pending */
i = old_queue;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].p)));
pbuf_free(arp_table[i].p);
arp_table[i].p = NULL;
#endif
/* no empty or recyclable entries found */
} else {
return (s8_t)ERR_MEM;
}
/* { empty or recyclable entry found } */
LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
if (arp_table[i].state != ETHARP_STATE_EMPTY)
{
snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
}
/* recycle entry (no-op for an already empty entry) */
arp_table[i].state = ETHARP_STATE_EMPTY;
/* IP address given? */
if (ipaddr != NULL) {
/* set IP address */
ip_addr_set(&arp_table[i].ipaddr, ipaddr);
}
arp_table[i].ctime = 0;
return (err_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 ipaddr IP address of the inserted ARP entry.
* @param ethaddr Ethernet address of the inserted ARP entry.
* @param flags Defines behaviour:
* - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
* only existing ARP entries will be updated.
*
* @return
* - ERR_OK Succesfully updated ARP cache.
* - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
*
* @see pbuf_free()
*/
static err_t
update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
{
s8_t i;
u8_t k;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("update_arp_entry()\n"));
LWIP_ASSERT("netif->hwaddr_len != 0", netif->hwaddr_len != 0);
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("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(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]));
/* 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;
}
/* find or create ARP entry */
i = find_entry(ipaddr, flags);
/* bail out if no entry could be found */
if (i < 0) return (err_t)i;
/* mark it stable */
arp_table[i].state = ETHARP_STATE_STABLE;
/* record network interface */
arp_table[i].netif = netif;
/* insert in SNMP ARP index tree */
snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
/* update address */
k = netif->hwaddr_len;
while (k > 0) {
k--;
arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
}
/* reset time stamp */
arp_table[i].ctime = 0;
/* this is where we will send out queued packets! */
#if ARP_QUEUEING
while (arp_table[i].p != NULL) {
/* get the first packet on the queue */
struct pbuf *p = arp_table[i].p;
/* Ethernet header */
struct eth_hdr *ethhdr = p->payload;
/* remember (and reference) remainder of queue */
/* note: this will also terminate the p pbuf chain */
arp_table[i].p = pbuf_dequeue(p);
/* fill-in Ethernet header */
k = netif->hwaddr_len;
while(k > 0) {
k--;
ethhdr->dest.addr[k] = ethaddr->addr[k];
ethhdr->src.addr[k] = netif->hwaddr[k];
}
ethhdr->type = htons(ETHTYPE_IP);
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: sending queued IP packet %p.\n", (void *)p));
/* send the queued IP packet */
netif->linkoutput(netif, p);
/* free the queued IP packet */
pbuf_free(p);
}
#endif
return ERR_OK;
}
/**
* 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
*/
s8_t
etharp_find_addr(struct netif *netif, struct ip_addr *ipaddr,
struct eth_addr **eth_ret, struct ip_addr **ip_ret)
{
s8_t i;
i = 0;
while (i < ARP_TABLE_SIZE)
{
if ((arp_table[i].state == ETHARP_STATE_STABLE) &&
(arp_table[i].netif == netif) &&
ip_addr_cmp(ipaddr, &arp_table[i].ipaddr) )
{
*eth_ret = &arp_table[i].ethaddr;
*ip_ret = &arp_table[i].ipaddr;
return i;
}
i++;
}
return -1;
}
/**
* Updates the ARP table using the given IP packet.
*
* Uses the incoming IP packet's source address to update the
* ARP cache for the local network. The function does not alter
* or free the packet. This function must be called before the
* packet p is passed to the IP layer.
*
* @param netif The lwIP network interface on which the IP packet pbuf arrived.
* @param pbuf The IP packet that arrived on netif.
*
* @return NULL
*
* @see pbuf_free()
*/
void
etharp_ip_input(struct netif *netif, struct pbuf *p)
{
struct ethip_hdr *hdr;
LWIP_ASSERT("netif != NULL", netif != NULL);
/* Only insert an entry if the source IP address of the
incoming IP packet comes from a host on the local network. */
hdr = p->payload;
/* source is not on the local network? */
if (!ip_addr_netcmp(&(hdr->ip.src), &(netif->ip_addr), &(netif->netmask))) {
/* do nothing */
return;
}
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
/* update ARP table */
/* @todo We could use ETHARP_TRY_HARD if we think we are going to talk
* back soon (for example, if the destination IP address is ours. */
update_arp_entry(netif, &(hdr->ip.src), &(hdr->eth.src), 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 netif The lwIP network interface on which the ARP packet pbuf arrived.
* @param pbuf The ARP packet that arrived on netif. Is freed by this function.
* @param ethaddr Ethernet address of netif.
*
* @return NULL
*
* @see pbuf_free()
*/
void
etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
{
struct etharp_hdr *hdr;
/* these are aligned properly, whereas the ARP header fields might not be */
struct ip_addr sipaddr, dipaddr;
u8_t i;
u8_t for_us;
LWIP_ASSERT("netif != NULL", netif != NULL);
/* drop short ARP packets */
if (p->tot_len < sizeof(struct etharp_hdr)) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 1, ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len, (s16_t)sizeof(struct etharp_hdr)));
pbuf_free(p);
return;
}
hdr = p->payload;
/* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
* structure packing (not using structure copy which breaks strict-aliasing rules). */
memcpy(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
memcpy(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
/* this interface is not configured? */
if (netif->ip_addr.addr == 0) {
for_us = 0;
} else {
/* ARP packet directed to us? */
for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr));
}
/* ARP message directed to us? */
if (for_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. */
update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD);
/* ARP message not directed to us? */
} else {
/* update the source IP address in the cache, if present */
update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), 0);
}
/* now act on the message itself */
switch (htons(hdr->opcode)) {
/* ARP request? */
case 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 possiby send out an IP packet that was queued on it. */
LWIP_DEBUGF (ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
/* ARP request for our address? */
if (for_us) {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
/* re-use pbuf to send ARP reply */
hdr->opcode = htons(ARP_REPLY);
hdr->dipaddr = hdr->sipaddr;
hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr;
i = netif->hwaddr_len;
while(i > 0) {
i--;
hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
hdr->shwaddr.addr[i] = ethaddr->addr[i];
hdr->ethhdr.dest.addr[i] = hdr->dhwaddr.addr[i];
hdr->ethhdr.src.addr[i] = ethaddr->addr[i];
}
hdr->hwtype = htons(HWTYPE_ETHERNET);
ARPH_HWLEN_SET(hdr, netif->hwaddr_len);
hdr->proto = htons(ETHTYPE_IP);
ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr));
hdr->ethhdr.type = htons(ETHTYPE_ARP);
/* return ARP reply */
netif->linkoutput(netif, p);
/* we are not configured? */
} else if (netif->ip_addr.addr == 0) {
/* { for_us == 0 and netif->ip_addr.addr == 0 } */
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_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 | DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
}
break;
case ARP_REPLY:
/* ARP reply. We already updated the ARP cache earlier. */
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_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
break;
default:
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
break;
}
/* free ARP packet */
pbuf_free(p);
}
/**
* Resolve and fill-in Ethernet address header for outgoing 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 ipaddr The IP address of the packet destination.
* @param pbuf The pbuf(s) containing the IP packet to be sent.
*
* @return
* - ERR_RTE No route to destination (no gateway to external networks),
* or the return type of either etharp_query() or netif->linkoutput().
*/
err_t
etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
{
struct eth_addr *dest, *srcaddr, mcastaddr;
struct eth_hdr *ethhdr;
u8_t i;
/* make room for Ethernet header - should not fail */
if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
/* bail out */
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n"));
LINK_STATS_INC(link.lenerr);
return ERR_BUF;
}
/* assume unresolved Ethernet address */
dest = 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 (ip_addr_isbroadcast(ipaddr, netif)) {
/* broadcast on Ethernet also */
dest = (struct eth_addr *)&ethbroadcast;
/* multicast destination IP address? */
} else if (ip_addr_ismulticast(ipaddr)) {
/* Hash IP multicast address to MAC address.*/
mcastaddr.addr[0] = 0x01;
mcastaddr.addr[1] = 0x00;
mcastaddr.addr[2] = 0x5e;
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 {
/* outside local network? */
if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
/* interface has default gateway? */
if (netif->gw.addr != 0) {
/* 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;
}
}
/* queue on destination Ethernet address belonging to ipaddr */
return etharp_query(netif, ipaddr, q);
}
/* continuation for multicast/broadcast destinations */
/* obtain source Ethernet address of the given interface */
srcaddr = (struct eth_addr *)netif->hwaddr;
ethhdr = q->payload;
i = netif->hwaddr_len;
while(i > 0) {
i--;
ethhdr->dest.addr[i] = dest->addr[i];
ethhdr->src.addr[i] = srcaddr->addr[i];
}
ethhdr->type = htons(ETHTYPE_IP);
/* send packet directly on the link */
return netif->linkoutput(netif, q);
}
/**
* 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.
*
* @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, struct ip_addr *ipaddr, struct pbuf *q)
{
struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
err_t result = ERR_MEM;
s8_t i; /* ARP entry index */
u8_t k; /* Ethernet address octet index */
/* non-unicast address? */
if (ip_addr_isbroadcast(ipaddr, netif) ||
ip_addr_ismulticast(ipaddr) ||
ip_addr_isany(ipaddr)) {
LWIP_DEBUGF(ETHARP_DEBUG | 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 = find_entry(ipaddr, ETHARP_TRY_HARD);
/* could not find or create entry? */
if (i < 0)
{
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
if (q) LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: packet dropped\n"));
return (err_t)i;
}
/* mark a fresh entry as pending (we just sent a request) */
if (arp_table[i].state == ETHARP_STATE_EMPTY) {
arp_table[i].state = ETHARP_STATE_PENDING;
}
/* { 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 pending entry? or an implicit query request? */
if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
/* try to resolve it; send out ARP request */
result = etharp_request(netif, ipaddr);
}
/* packet given? */
if (q != NULL) {
/* stable entry? */
if (arp_table[i].state == ETHARP_STATE_STABLE) {
/* we have a valid IP->Ethernet address mapping,
* fill in the Ethernet header for the outgoing packet */
struct eth_hdr *ethhdr = q->payload;
k = netif->hwaddr_len;
while(k > 0) {
k--;
ethhdr->dest.addr[k] = arp_table[i].ethaddr.addr[k];
ethhdr->src.addr[k] = srcaddr->addr[k];
}
ethhdr->type = htons(ETHTYPE_IP);
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: sending packet %p\n", (void *)q));
/* send the packet */
result = netif->linkoutput(netif, q);
/* pending entry? (either just created or already pending */
} else if (arp_table[i].state == ETHARP_STATE_PENDING) {
#if ARP_QUEUEING /* queue the given q packet */
struct pbuf *p;
/* copy any PBUF_REF referenced payloads into PBUF_RAM */
/* (the caller of lwIP assumes the referenced payload can be
* freed after it returns from the lwIP call that brought us here) */
p = pbuf_take(q);
/* packet could be taken over? */
if (p != NULL) {
/* queue packet ... */
if (arp_table[i].p == NULL) {
/* ... in the empty queue */
pbuf_ref(p);
arp_table[i].p = p;
#if 0 /* multi-packet-queueing disabled, see bug #11400 */
} else {
/* ... at tail of non-empty queue */
pbuf_queue(arp_table[i].p, p);
#endif
}
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
result = ERR_OK;
} else {
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
/* { result == ERR_MEM } through initialization */
}
#else /* ARP_QUEUEING == 0 */
/* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
/* { result == ERR_MEM } through initialization */
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
#endif
}
}
return result;
}
err_t etharp_request(struct netif *netif, struct ip_addr *ipaddr)
{
struct pbuf *p;
struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
err_t result = ERR_OK;
u8_t k; /* ARP entry index */
/* allocate a pbuf for the outgoing ARP request packet */
p = pbuf_alloc(PBUF_LINK, sizeof(struct etharp_hdr), PBUF_RAM);
/* could allocate a pbuf for an ARP request? */
if (p != NULL) {
struct etharp_hdr *hdr = p->payload;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_request: sending ARP request.\n"));
hdr->opcode = htons(ARP_REQUEST);
k = netif->hwaddr_len;
while(k > 0) {
k--;
hdr->shwaddr.addr[k] = srcaddr->addr[k];
/* the hardware address is what we ask for, in
* a request it is a don't-care value, we use zeroes */
hdr->dhwaddr.addr[k] = 0x00;
}
hdr->dipaddr = *(struct ip_addr2 *)ipaddr;
hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr;
hdr->hwtype = htons(HWTYPE_ETHERNET);
ARPH_HWLEN_SET(hdr, netif->hwaddr_len);
hdr->proto = htons(ETHTYPE_IP);
ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr));
k = netif->hwaddr_len;
while(k > 0) {
k--;
/* broadcast to all network interfaces on the local network */
hdr->ethhdr.dest.addr[k] = 0xff;
hdr->ethhdr.src.addr[k] = srcaddr->addr[k];
}
hdr->ethhdr.type = htons(ETHTYPE_ARP);
/* send ARP query */
result = netif->linkoutput(netif, p);
/* free ARP query packet */
pbuf_free(p);
p = NULL;
/* could not allocate pbuf for ARP request */
} else {
result = ERR_MEM;
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_request: could not allocate pbuf for ARP request.\n"));
}
return result;
}
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