| /** |
| * @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; |
| } |