/** | |
* @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 "lwip/opt.h" | |
#include "lwip/inet.h" | |
#include "netif/etharp.h" | |
#include "lwip/ip.h" | |
#include "lwip/stats.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; | |
}; | |
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; | |
} | |
} | |
/** | |
* 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) { | |
#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); | |
/* 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, 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; | |
LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i)); | |
/* update address */ | |
for (k = 0; k < netif->hwaddr_len; ++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 */ | |
for (k = 0; k < netif->hwaddr_len; ++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; | |
} | |
/** | |
* 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, sizeof(struct etharp_hdr))); | |
pbuf_free(p); | |
return; | |
} | |
hdr = p->payload; | |
/* get aligned copies of addresses */ | |
*(struct ip_addr2 *)&sipaddr = hdr->sipaddr; | |
*(struct ip_addr2 *)&dipaddr = hdr->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; | |
for(i = 0; i < netif->hwaddr_len; ++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 *)ðbroadcast; | |
/* 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; | |
for (i = 0; i < netif->hwaddr_len; 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; | |
for(k = 0; k < netif->hwaddr_len; 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); | |
for (k = 0; k < netif->hwaddr_len; 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)); | |
for (k = 0; k < netif->hwaddr_len; ++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; | |
} |