etharp.c

00001 /**
00002  * @file
00003  * Address Resolution Protocol module for IP over Ethernet
00004  *
00005  * Functionally, ARP is divided into two parts. The first maps an IP address
00006  * to a physical address when sending a packet, and the second part answers
00007  * requests from other machines for our physical address.
00008  *
00009  * This implementation complies with RFC 826 (Ethernet ARP). It supports
00010  * Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6
00011  * if an interface calls etharp_gratuitous(our_netif) upon address change.
00012  */
00013 
00014 /*
00015  * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
00016  * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv>
00017  * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands.
00018  * All rights reserved.
00019  *
00020  * Redistribution and use in source and binary forms, with or without modification,
00021  * are permitted provided that the following conditions are met:
00022  *
00023  * 1. Redistributions of source code must retain the above copyright notice,
00024  *    this list of conditions and the following disclaimer.
00025  * 2. Redistributions in binary form must reproduce the above copyright notice,
00026  *    this list of conditions and the following disclaimer in the documentation
00027  *    and/or other materials provided with the distribution.
00028  * 3. The name of the author may not be used to endorse or promote products
00029  *    derived from this software without specific prior written permission.
00030  *
00031  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00032  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00033  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00034  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00035  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00036  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00037  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00038  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00039  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00040  * OF SUCH DAMAGE.
00041  *
00042  * This file is part of the lwIP TCP/IP stack.
00043  *
00044  */
00045  
00046 #include "lwip/opt.h"
00047 
00048 #if LWIP_ARP || LWIP_ETHERNET
00049 
00050 #include "lwip/ip_addr.h"
00051 #include "lwip/def.h"
00052 #include "lwip/ip.h"
00053 #include "lwip/stats.h"
00054 #include "lwip/snmp.h"
00055 #include "lwip/dhcp.h "
00056 #include "lwip/autoip.h"
00057 #include "netif/etharp.h"
00058 
00059 #if PPPOE_SUPPORT
00060 #include "netif/ppp_oe.h"
00061 #endif /* PPPOE_SUPPORT */
00062 
00063 #include <string.h>
00064 
00065 const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
00066 const struct eth_addr ethzero = {{0,0,0,0,0,0}};
00067 
00068 #if LWIP_ARP /* don't build if not configured for use in lwipopts.h */
00069 
00070 /** the time an ARP entry stays valid after its last update,
00071  *  for ARP_TMR_INTERVAL = 5000, this is
00072  *  (240 * 5) seconds = 20 minutes.
00073  */
00074 #define ARP_MAXAGE 240
00075 /** the time an ARP entry stays pending after first request,
00076  *  for ARP_TMR_INTERVAL = 5000, this is
00077  *  (2 * 5) seconds = 10 seconds.
00078  * 
00079  *  @internal Keep this number at least 2, otherwise it might
00080  *  run out instantly if the timeout occurs directly after a request.
00081  */
00082 #define ARP_MAXPENDING 2
00083 
00084 #define HWTYPE_ETHERNET 1
00085 
00086 #define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8)
00087 #define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff)
00088 
00089 #define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8))
00090 #define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8))
00091 
00092 enum etharp_state {
00093   ETHARP_STATE_EMPTY = 0,
00094   ETHARP_STATE_PENDING,
00095   ETHARP_STATE_STABLE
00096 };
00097 
00098 struct etharp_entry {
00099 #if ARP_QUEUEING
00100   /** 
00101    * Pointer to queue of pending outgoing packets on this ARP entry.
00102    */
00103   struct etharp_q_entry *q;
00104 #endif /* ARP_QUEUEING */
00105   ip_addr_t ipaddr;
00106   struct eth_addr ethaddr;
00107   enum etharp_state state;
00108   u8_t ctime;
00109   struct netif *netif;
00110 };
00111 
00112 static struct etharp_entry arp_table[ARP_TABLE_SIZE];
00113 #if !LWIP_NETIF_HWADDRHINT
00114 static u8_t etharp_cached_entry;
00115 #endif /* !LWIP_NETIF_HWADDRHINT */
00116 
00117 /**
00118  * Try hard to create a new entry - we want the IP address to appear in
00119  * the cache (even if this means removing an active entry or so). */
00120 #define ETHARP_TRY_HARD 1
00121 #define ETHARP_FIND_ONLY  2
00122 
00123 #if LWIP_NETIF_HWADDRHINT
00124 #define NETIF_SET_HINT(netif, hint)  if (((netif) != NULL) && ((netif)->addr_hint != NULL))  \
00125                                       *((netif)->addr_hint) = (hint);
00126 static s8_t find_entry(ip_addr_t *ipaddr, u8_t flags, struct netif *netif);
00127 #else /* LWIP_NETIF_HWADDRHINT */
00128 static s8_t find_entry(ip_addr_t *ipaddr, u8_t flags);
00129 #endif /* LWIP_NETIF_HWADDRHINT */
00130 
00131 static err_t update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags);
00132 
00133 
00134 /* Some checks, instead of etharp_init(): */
00135 #if (LWIP_ARP && (ARP_TABLE_SIZE > 0x7f))
00136   #error "If you want to use ARP, ARP_TABLE_SIZE must fit in an s8_t, so, you have to reduce it in your lwipopts.h"
00137 #endif
00138 
00139 
00140 #if ARP_QUEUEING
00141 /**
00142  * Free a complete queue of etharp entries
00143  *
00144  * @param q a qeueue of etharp_q_entry's to free
00145  */
00146 static void
00147 free_etharp_q(struct etharp_q_entry *q)
00148 {
00149   struct etharp_q_entry *r;
00150   LWIP_ASSERT("q != NULL", q != NULL);
00151   LWIP_ASSERT("q->p != NULL", q->p != NULL);
00152   while (q) {
00153     r = q;
00154     q = q->next;
00155     LWIP_ASSERT("r->p != NULL", (r->p != NULL));
00156     pbuf_free(r->p);
00157     memp_free(MEMP_ARP_QUEUE, r);
00158   }
00159 }
00160 #endif /* ARP_QUEUEING */
00161 
00162 /**
00163  * Clears expired entries in the ARP table.
00164  *
00165  * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
00166  * in order to expire entries in the ARP table.
00167  */
00168 void
00169 etharp_tmr(void)
00170 {
00171   u8_t i;
00172 
00173   LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
00174   /* remove expired entries from the ARP table */
00175   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00176     arp_table[i].ctime++;
00177     if (((arp_table[i].state == ETHARP_STATE_STABLE) &&
00178          (arp_table[i].ctime >= ARP_MAXAGE)) ||
00179         ((arp_table[i].state == ETHARP_STATE_PENDING)  &&
00180          (arp_table[i].ctime >= ARP_MAXPENDING))) {
00181          /* pending or stable entry has become old! */
00182       LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
00183            arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
00184       /* clean up entries that have just been expired */
00185       /* remove from SNMP ARP index tree */
00186       snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00187 #if ARP_QUEUEING
00188       /* and empty packet queue */
00189       if (arp_table[i].q != NULL) {
00190         /* remove all queued packets */
00191         LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
00192         free_etharp_q(arp_table[i].q);
00193         arp_table[i].q = NULL;
00194       }
00195 #endif /* ARP_QUEUEING */
00196       /* recycle entry for re-use */      
00197       arp_table[i].state = ETHARP_STATE_EMPTY;
00198     }
00199 #if ARP_QUEUEING
00200     /* still pending entry? (not expired) */
00201     if (arp_table[i].state == ETHARP_STATE_PENDING) {
00202         /* resend an ARP query here? */
00203     }
00204 #endif /* ARP_QUEUEING */
00205   }
00206 }
00207 
00208 /**
00209  * Search the ARP table for a matching or new entry.
00210  * 
00211  * If an IP address is given, return a pending or stable ARP entry that matches
00212  * the address. If no match is found, create a new entry with this address set,
00213  * but in state ETHARP_EMPTY. The caller must check and possibly change the
00214  * state of the returned entry.
00215  * 
00216  * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
00217  * 
00218  * In all cases, attempt to create new entries from an empty entry. If no
00219  * empty entries are available and ETHARP_TRY_HARD flag is set, recycle
00220  * old entries. Heuristic choose the least important entry for recycling.
00221  *
00222  * @param ipaddr IP address to find in ARP cache, or to add if not found.
00223  * @param flags
00224  * - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of
00225  * active (stable or pending) entries.
00226  *  
00227  * @return The ARP entry index that matched or is created, ERR_MEM if no
00228  * entry is found or could be recycled.
00229  */
00230 static s8_t
00231 #if LWIP_NETIF_HWADDRHINT
00232 find_entry(ip_addr_t *ipaddr, u8_t flags, struct netif *netif)
00233 #else /* LWIP_NETIF_HWADDRHINT */
00234 find_entry(ip_addr_t *ipaddr, u8_t flags)
00235 #endif /* LWIP_NETIF_HWADDRHINT */
00236 {
00237   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
00238   s8_t empty = ARP_TABLE_SIZE;
00239   u8_t i = 0, age_pending = 0, age_stable = 0;
00240 #if ARP_QUEUEING
00241   /* oldest entry with packets on queue */
00242   s8_t old_queue = ARP_TABLE_SIZE;
00243   /* its age */
00244   u8_t age_queue = 0;
00245 #endif /* ARP_QUEUEING */
00246 
00247   /* First, test if the last call to this function asked for the
00248    * same address. If so, we're really fast! */
00249   if (ipaddr) {
00250     /* ipaddr to search for was given */
00251 #if LWIP_NETIF_HWADDRHINT
00252     if ((netif != NULL) && (netif->addr_hint != NULL)) {
00253       /* per-pcb cached entry was given */
00254       u8_t per_pcb_cache = *(netif->addr_hint);
00255       if ((per_pcb_cache < ARP_TABLE_SIZE) && arp_table[per_pcb_cache].state == ETHARP_STATE_STABLE) {
00256         /* the per-pcb-cached entry is stable */
00257         if (ip_addr_cmp(ipaddr, &arp_table[per_pcb_cache].ipaddr)) {
00258           /* per-pcb cached entry was the right one! */
00259           ETHARP_STATS_INC(etharp.cachehit);
00260           return per_pcb_cache;
00261         }
00262       }
00263     }
00264 #else /* #if LWIP_NETIF_HWADDRHINT */
00265     if (arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) {
00266       /* the cached entry is stable */
00267       if (ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr)) {
00268         /* cached entry was the right one! */
00269         ETHARP_STATS_INC(etharp.cachehit);
00270         return etharp_cached_entry;
00271       }
00272     }
00273 #endif /* #if LWIP_NETIF_HWADDRHINT */
00274   }
00275 
00276   /**
00277    * a) do a search through the cache, remember candidates
00278    * b) select candidate entry
00279    * c) create new entry
00280    */
00281 
00282   /* a) in a single search sweep, do all of this
00283    * 1) remember the first empty entry (if any)
00284    * 2) remember the oldest stable entry (if any)
00285    * 3) remember the oldest pending entry without queued packets (if any)
00286    * 4) remember the oldest pending entry with queued packets (if any)
00287    * 5) search for a matching IP entry, either pending or stable
00288    *    until 5 matches, or all entries are searched for.
00289    */
00290 
00291   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00292     /* no empty entry found yet and now we do find one? */
00293     if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) {
00294       LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
00295       /* remember first empty entry */
00296       empty = i;
00297     }
00298     /* pending entry? */
00299     else if (arp_table[i].state == ETHARP_STATE_PENDING) {
00300       /* if given, does IP address match IP address in ARP entry? */
00301       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00302         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
00303         /* found exact IP address match, simply bail out */
00304 #if LWIP_NETIF_HWADDRHINT
00305         NETIF_SET_HINT(netif, i);
00306 #else /* #if LWIP_NETIF_HWADDRHINT */
00307         etharp_cached_entry = i;
00308 #endif /* #if LWIP_NETIF_HWADDRHINT */
00309         return i;
00310 #if ARP_QUEUEING
00311       /* pending with queued packets? */
00312       } else if (arp_table[i].q != NULL) {
00313         if (arp_table[i].ctime >= age_queue) {
00314           old_queue = i;
00315           age_queue = arp_table[i].ctime;
00316         }
00317 #endif /* ARP_QUEUEING */
00318       /* pending without queued packets? */
00319       } else {
00320         if (arp_table[i].ctime >= age_pending) {
00321           old_pending = i;
00322           age_pending = arp_table[i].ctime;
00323         }
00324       }        
00325     }
00326     /* stable entry? */
00327     else if (arp_table[i].state == ETHARP_STATE_STABLE) {
00328       /* if given, does IP address match IP address in ARP entry? */
00329       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00330         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
00331         /* found exact IP address match, simply bail out */
00332 #if LWIP_NETIF_HWADDRHINT
00333         NETIF_SET_HINT(netif, i);
00334 #else /* #if LWIP_NETIF_HWADDRHINT */
00335         etharp_cached_entry = i;
00336 #endif /* #if LWIP_NETIF_HWADDRHINT */
00337         return i;
00338       /* remember entry with oldest stable entry in oldest, its age in maxtime */
00339       } else if (arp_table[i].ctime >= age_stable) {
00340         old_stable = i;
00341         age_stable = arp_table[i].ctime;
00342       }
00343     }
00344   }
00345   /* { we have no match } => try to create a new entry */
00346    
00347   /* don't create new entry, only search? */
00348   if (((flags & ETHARP_FIND_ONLY) != 0) ||
00349       /* or no empty entry found and not allowed to recycle? */
00350       ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0))) {
00351     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
00352     return (s8_t)ERR_MEM;
00353   }
00354   
00355   /* b) choose the least destructive entry to recycle:
00356    * 1) empty entry
00357    * 2) oldest stable entry
00358    * 3) oldest pending entry without queued packets
00359    * 4) oldest pending entry with queued packets
00360    * 
00361    * { ETHARP_TRY_HARD is set at this point }
00362    */ 
00363 
00364   /* 1) empty entry available? */
00365   if (empty < ARP_TABLE_SIZE) {
00366     i = empty;
00367     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
00368   }
00369   /* 2) found recyclable stable entry? */
00370   else if (old_stable < ARP_TABLE_SIZE) {
00371     /* recycle oldest stable*/
00372     i = old_stable;
00373     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
00374 #if ARP_QUEUEING
00375     /* no queued packets should exist on stable entries */
00376     LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
00377 #endif /* ARP_QUEUEING */
00378   /* 3) found recyclable pending entry without queued packets? */
00379   } else if (old_pending < ARP_TABLE_SIZE) {
00380     /* recycle oldest pending */
00381     i = old_pending;
00382     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
00383 #if ARP_QUEUEING
00384   /* 4) found recyclable pending entry with queued packets? */
00385   } else if (old_queue < ARP_TABLE_SIZE) {
00386     /* recycle oldest pending */
00387     i = old_queue;
00388     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].q)));
00389     free_etharp_q(arp_table[i].q);
00390     arp_table[i].q = NULL;
00391 #endif /* ARP_QUEUEING */
00392     /* no empty or recyclable entries found */
00393   } else {
00394     return (s8_t)ERR_MEM;
00395   }
00396 
00397   /* { empty or recyclable entry found } */
00398   LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00399 
00400   if (arp_table[i].state != ETHARP_STATE_EMPTY)
00401   {
00402     snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00403   }
00404   /* recycle entry (no-op for an already empty entry) */
00405   arp_table[i].state = ETHARP_STATE_EMPTY;
00406 
00407   /* IP address given? */
00408   if (ipaddr != NULL) {
00409     /* set IP address */
00410     ip_addr_copy(arp_table[i].ipaddr, *ipaddr);
00411   }
00412   arp_table[i].ctime = 0;
00413 #if LWIP_NETIF_HWADDRHINT
00414   NETIF_SET_HINT(netif, i);
00415 #else /* #if LWIP_NETIF_HWADDRHINT */
00416   etharp_cached_entry = i;
00417 #endif /* #if LWIP_NETIF_HWADDRHINT */
00418   return (err_t)i;
00419 }
00420 
00421 /**
00422  * Send an IP packet on the network using netif->linkoutput
00423  * The ethernet header is filled in before sending.
00424  *
00425  * @params netif the lwIP network interface on which to send the packet
00426  * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
00427  * @params src the source MAC address to be copied into the ethernet header
00428  * @params dst the destination MAC address to be copied into the ethernet header
00429  * @return ERR_OK if the packet was sent, any other err_t on failure
00430  */
00431 static err_t
00432 etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
00433 {
00434   struct eth_hdr *ethhdr = (struct eth_hdr *)p->payload;
00435   u8_t k;
00436 
00437   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00438               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00439   k = ETHARP_HWADDR_LEN;
00440   while(k > 0) {
00441     k--;
00442     ethhdr->dest.addr[k] = dst->addr[k];
00443     ethhdr->src.addr[k]  = src->addr[k];
00444   }
00445   ethhdr->type = htons(ETHTYPE_IP);
00446   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
00447   /* send the packet */
00448   return netif->linkoutput(netif, p);
00449 }
00450 
00451 /**
00452  * Update (or insert) a IP/MAC address pair in the ARP cache.
00453  *
00454  * If a pending entry is resolved, any queued packets will be sent
00455  * at this point.
00456  * 
00457  * @param ipaddr IP address of the inserted ARP entry.
00458  * @param ethaddr Ethernet address of the inserted ARP entry.
00459  * @param flags Defines behaviour:
00460  * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
00461  * only existing ARP entries will be updated.
00462  *
00463  * @return
00464  * - ERR_OK Succesfully updated ARP cache.
00465  * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
00466  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00467  *
00468  * @see pbuf_free()
00469  */
00470 static err_t
00471 update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
00472 {
00473   s8_t i;
00474   u8_t k;
00475   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry()\n"));
00476   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
00477   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_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",
00478     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00479     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00480     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00481   /* non-unicast address? */
00482   if (ip_addr_isany(ipaddr) ||
00483       ip_addr_isbroadcast(ipaddr, netif) ||
00484       ip_addr_ismulticast(ipaddr)) {
00485     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
00486     return ERR_ARG;
00487   }
00488   /* find or create ARP entry */
00489 #if LWIP_NETIF_HWADDRHINT
00490   i = find_entry(ipaddr, flags, netif);
00491 #else /* LWIP_NETIF_HWADDRHINT */
00492   i = find_entry(ipaddr, flags);
00493 #endif /* LWIP_NETIF_HWADDRHINT */
00494   /* bail out if no entry could be found */
00495   if (i < 0)
00496     return (err_t)i;
00497   
00498   /* mark it stable */
00499   arp_table[i].state = ETHARP_STATE_STABLE;
00500   /* record network interface */
00501   arp_table[i].netif = netif;
00502 
00503   /* insert in SNMP ARP index tree */
00504   snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
00505 
00506   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
00507   /* update address */
00508   k = ETHARP_HWADDR_LEN;
00509   while (k > 0) {
00510     k--;
00511     arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
00512   }
00513   /* reset time stamp */
00514   arp_table[i].ctime = 0;
00515 #if ARP_QUEUEING
00516   /* this is where we will send out queued packets! */
00517   while (arp_table[i].q != NULL) {
00518     struct pbuf *p;
00519     /* remember remainder of queue */
00520     struct etharp_q_entry *q = arp_table[i].q;
00521     /* pop first item off the queue */
00522     arp_table[i].q = q->next;
00523     /* get the packet pointer */
00524     p = q->p;
00525     /* now queue entry can be freed */
00526     memp_free(MEMP_ARP_QUEUE, q);
00527     /* send the queued IP packet */
00528     etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
00529     /* free the queued IP packet */
00530     pbuf_free(p);
00531   }
00532 #endif /* ARP_QUEUEING */
00533   return ERR_OK;
00534 }
00535 
00536 /**
00537  * Finds (stable) ethernet/IP address pair from ARP table
00538  * using interface and IP address index.
00539  * @note the addresses in the ARP table are in network order!
00540  *
00541  * @param netif points to interface index
00542  * @param ipaddr points to the (network order) IP address index
00543  * @param eth_ret points to return pointer
00544  * @param ip_ret points to return pointer
00545  * @return table index if found, -1 otherwise
00546  */
00547 s8_t
00548 etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
00549          struct eth_addr **eth_ret, ip_addr_t **ip_ret)
00550 {
00551   s8_t i;
00552 
00553   LWIP_UNUSED_ARG(netif);
00554 
00555 #if LWIP_NETIF_HWADDRHINT
00556   i = find_entry(ipaddr, ETHARP_FIND_ONLY, NULL);
00557 #else /* LWIP_NETIF_HWADDRHINT */
00558   i = find_entry(ipaddr, ETHARP_FIND_ONLY);
00559 #endif /* LWIP_NETIF_HWADDRHINT */
00560   if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) {
00561       *eth_ret = &arp_table[i].ethaddr;
00562       *ip_ret = &arp_table[i].ipaddr;
00563       return i;
00564   }
00565   return -1;
00566 }
00567 #if ETHARP_TRUST_IP_MAC
00568 /**
00569  * Updates the ARP table using the given IP packet.
00570  *
00571  * Uses the incoming IP packet's source address to update the
00572  * ARP cache for the local network. The function does not alter
00573  * or free the packet. This function must be called before the
00574  * packet p is passed to the IP layer.
00575  *
00576  * @param netif The lwIP network interface on which the IP packet pbuf arrived.
00577  * @param p The IP packet that arrived on netif.
00578  *
00579  * @return NULL
00580  *
00581  * @see pbuf_free()
00582  */
00583 static void
00584 etharp_ip_input(struct netif *netif, struct pbuf *p)
00585 {
00586   struct eth_hdr *ethhdr;
00587   struct ip_hdr *iphdr;
00588   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00589 
00590   /* Only insert an entry if the source IP address of the
00591      incoming IP packet comes from a host on the local network. */
00592   ethhdr = (struct eth_hdr *)p->payload;
00593   iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00594 #if ETHARP_SUPPORT_VLAN
00595   if (ethhdr->type == ETHTYPE_VLAN) {
00596     iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00597   }
00598 #endif /* ETHARP_SUPPORT_VLAN */
00599 
00600   /* source is not on the local network? */
00601   if (!ip_addr_netcmp(&(iphdr->src), &(netif->ip_addr), &(netif->netmask))) {
00602     /* do nothing */
00603     return;
00604   }
00605 
00606   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
00607   /* update the source IP address in the cache, if present */
00608   /* @todo We could use ETHARP_TRY_HARD if we think we are going to talk
00609    * back soon (for example, if the destination IP address is ours. */
00610   update_arp_entry(netif, &(iphdr->src), &(ethhdr->src), ETHARP_FIND_ONLY);
00611 }
00612 #endif /* ETHARP_TRUST_IP_MAC */
00613 
00614 /**
00615  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
00616  * send out queued IP packets. Updates cache with snooped address pairs.
00617  *
00618  * Should be called for incoming ARP packets. The pbuf in the argument
00619  * is freed by this function.
00620  *
00621  * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
00622  * @param ethaddr Ethernet address of netif.
00623  * @param p The ARP packet that arrived on netif. Is freed by this function.
00624  *
00625  * @return NULL
00626  *
00627  * @see pbuf_free()
00628  */
00629 static void
00630 etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
00631 {
00632   struct etharp_hdr *hdr;
00633   struct eth_hdr *ethhdr;
00634   /* these are aligned properly, whereas the ARP header fields might not be */
00635   ip_addr_t sipaddr, dipaddr;
00636   u8_t i;
00637   u8_t for_us;
00638 #if LWIP_AUTOIP
00639   const u8_t * ethdst_hwaddr;
00640 #endif /* LWIP_AUTOIP */
00641 
00642   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00643 
00644   /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
00645      since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
00646   if (p->len < SIZEOF_ETHARP_PACKET) {
00647     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00648       ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len,
00649       (s16_t)SIZEOF_ETHARP_PACKET));
00650     ETHARP_STATS_INC(etharp.lenerr);
00651     ETHARP_STATS_INC(etharp.drop);
00652     pbuf_free(p);
00653     return;
00654   }
00655 
00656   ethhdr = (struct eth_hdr *)p->payload;
00657   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00658 #if ETHARP_SUPPORT_VLAN
00659   if (ethhdr->type == ETHTYPE_VLAN) {
00660     hdr = (struct etharp_hdr *)(((u8_t*)ethhdr) + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00661   }
00662 #endif /* ETHARP_SUPPORT_VLAN */
00663 
00664   /* RFC 826 "Packet Reception": */
00665   if ((hdr->hwtype != htons(HWTYPE_ETHERNET)) ||
00666       (hdr->_hwlen_protolen != htons((ETHARP_HWADDR_LEN << 8) | sizeof(ip_addr_t))) ||
00667       (hdr->proto != htons(ETHTYPE_IP)) ||
00668       (ethhdr->type != htons(ETHTYPE_ARP)))  {
00669     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00670       ("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
00671       hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr), ethhdr->type));
00672     ETHARP_STATS_INC(etharp.proterr);
00673     ETHARP_STATS_INC(etharp.drop);
00674     pbuf_free(p);
00675     return;
00676   }
00677   ETHARP_STATS_INC(etharp.recv);
00678 
00679 #if LWIP_AUTOIP
00680   /* We have to check if a host already has configured our random
00681    * created link local address and continously check if there is
00682    * a host with this IP-address so we can detect collisions */
00683   autoip_arp_reply(netif, hdr);
00684 #endif /* LWIP_AUTOIP */
00685 
00686   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00687    * structure packing (not using structure copy which breaks strict-aliasing rules). */
00688   SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
00689   SMEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
00690 
00691   /* this interface is not configured? */
00692   if (ip_addr_isany(&netif->ip_addr)) {
00693     for_us = 0;
00694   } else {
00695     /* ARP packet directed to us? */
00696     for_us = (u8_t)ip_addr_cmp(&dipaddr, &(netif->ip_addr));
00697   }
00698 
00699   /* ARP message directed to us? */
00700   if (for_us) {
00701     /* add IP address in ARP cache; assume requester wants to talk to us.
00702      * can result in directly sending the queued packets for this host. */
00703     update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD);
00704   /* ARP message not directed to us? */
00705   } else {
00706     /* update the source IP address in the cache, if present */
00707     update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_FIND_ONLY);
00708   }
00709 
00710   /* now act on the message itself */
00711   switch (htons(hdr->opcode)) {
00712   /* ARP request? */
00713   case ARP_REQUEST:
00714     /* ARP request. If it asked for our address, we send out a
00715      * reply. In any case, we time-stamp any existing ARP entry,
00716      * and possiby send out an IP packet that was queued on it. */
00717 
00718     LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
00719     /* ARP request for our address? */
00720     if (for_us) {
00721 
00722       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
00723       /* Re-use pbuf to send ARP reply.
00724          Since we are re-using an existing pbuf, we can't call etharp_raw since
00725          that would allocate a new pbuf. */
00726       hdr->opcode = htons(ARP_REPLY);
00727 
00728       SMEMCPY(&hdr->dipaddr, &hdr->sipaddr, sizeof(ip_addr_t));
00729       SMEMCPY(&hdr->sipaddr, &netif->ip_addr, sizeof(ip_addr_t));
00730 
00731       LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00732                   (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00733       i = ETHARP_HWADDR_LEN;
00734 #if LWIP_AUTOIP
00735       /* If we are using Link-Local, all ARP packets that contain a Link-Local
00736        * 'sender IP address' MUST be sent using link-layer broadcast instead of
00737        * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
00738       ethdst_hwaddr = ip_addr_islinklocal(&netif->ip_addr) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
00739 #endif /* LWIP_AUTOIP */
00740 
00741       while(i > 0) {
00742         i--;
00743         hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
00744 #if LWIP_AUTOIP
00745         ethhdr->dest.addr[i] = ethdst_hwaddr[i];
00746 #else  /* LWIP_AUTOIP */
00747         ethhdr->dest.addr[i] = hdr->shwaddr.addr[i];
00748 #endif /* LWIP_AUTOIP */
00749         hdr->shwaddr.addr[i] = ethaddr->addr[i];
00750         ethhdr->src.addr[i] = ethaddr->addr[i];
00751       }
00752 
00753       /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
00754          are already correct, we tested that before */
00755 
00756       /* return ARP reply */
00757       netif->linkoutput(netif, p);
00758     /* we are not configured? */
00759     } else if (ip_addr_isany(&netif->ip_addr)) {
00760       /* { for_us == 0 and netif->ip_addr.addr == 0 } */
00761       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
00762     /* request was not directed to us */
00763     } else {
00764       /* { for_us == 0 and netif->ip_addr.addr != 0 } */
00765       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
00766     }
00767     break;
00768   case ARP_REPLY:
00769     /* ARP reply. We already updated the ARP cache earlier. */
00770     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
00771 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
00772     /* DHCP wants to know about ARP replies from any host with an
00773      * IP address also offered to us by the DHCP server. We do not
00774      * want to take a duplicate IP address on a single network.
00775      * @todo How should we handle redundant (fail-over) interfaces? */
00776     dhcp_arp_reply(netif, &sipaddr);
00777 #endif /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */
00778     break;
00779   default:
00780     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
00781     ETHARP_STATS_INC(etharp.err);
00782     break;
00783   }
00784   /* free ARP packet */
00785   pbuf_free(p);
00786 }
00787 
00788 /**
00789  * Resolve and fill-in Ethernet address header for outgoing IP packet.
00790  *
00791  * For IP multicast and broadcast, corresponding Ethernet addresses
00792  * are selected and the packet is transmitted on the link.
00793  *
00794  * For unicast addresses, the packet is submitted to etharp_query(). In
00795  * case the IP address is outside the local network, the IP address of
00796  * the gateway is used.
00797  *
00798  * @param netif The lwIP network interface which the IP packet will be sent on.
00799  * @param q The pbuf(s) containing the IP packet to be sent.
00800  * @param ipaddr The IP address of the packet destination.
00801  *
00802  * @return
00803  * - ERR_RTE No route to destination (no gateway to external networks),
00804  * or the return type of either etharp_query() or etharp_send_ip().
00805  */
00806 err_t
00807 etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
00808 {
00809   struct eth_addr *dest, mcastaddr;
00810 
00811   /* make room for Ethernet header - should not fail */
00812   if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
00813     /* bail out */
00814     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
00815       ("etharp_output: could not allocate room for header.\n"));
00816     LINK_STATS_INC(link.lenerr);
00817     return ERR_BUF;
00818   }
00819 
00820   /* assume unresolved Ethernet address */
00821   dest = NULL;
00822   /* Determine on destination hardware address. Broadcasts and multicasts
00823    * are special, other IP addresses are looked up in the ARP table. */
00824 
00825   /* broadcast destination IP address? */
00826   if (ip_addr_isbroadcast(ipaddr, netif)) {
00827     /* broadcast on Ethernet also */
00828     dest = (struct eth_addr *)&ethbroadcast;
00829   /* multicast destination IP address? */
00830   } else if (ip_addr_ismulticast(ipaddr)) {
00831     /* Hash IP multicast address to MAC address.*/
00832     mcastaddr.addr[0] = 0x01;
00833     mcastaddr.addr[1] = 0x00;
00834     mcastaddr.addr[2] = 0x5e;
00835     mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
00836     mcastaddr.addr[4] = ip4_addr3(ipaddr);
00837     mcastaddr.addr[5] = ip4_addr4(ipaddr);
00838     /* destination Ethernet address is multicast */
00839     dest = &mcastaddr;
00840   /* unicast destination IP address? */
00841   } else {
00842     /* outside local network? */
00843     if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask)) &&
00844         !ip_addr_islinklocal(ipaddr)) {
00845       /* interface has default gateway? */
00846       if (!ip_addr_isany(&netif->gw)) {
00847         /* send to hardware address of default gateway IP address */
00848         ipaddr = &(netif->gw);
00849       /* no default gateway available */
00850       } else {
00851         /* no route to destination error (default gateway missing) */
00852         return ERR_RTE;
00853       }
00854     }
00855     /* queue on destination Ethernet address belonging to ipaddr */
00856     return etharp_query(netif, ipaddr, q);
00857   }
00858 
00859   /* continuation for multicast/broadcast destinations */
00860   /* obtain source Ethernet address of the given interface */
00861   /* send packet directly on the link */
00862   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
00863 }
00864 
00865 /**
00866  * Send an ARP request for the given IP address and/or queue a packet.
00867  *
00868  * If the IP address was not yet in the cache, a pending ARP cache entry
00869  * is added and an ARP request is sent for the given address. The packet
00870  * is queued on this entry.
00871  *
00872  * If the IP address was already pending in the cache, a new ARP request
00873  * is sent for the given address. The packet is queued on this entry.
00874  *
00875  * If the IP address was already stable in the cache, and a packet is
00876  * given, it is directly sent and no ARP request is sent out. 
00877  * 
00878  * If the IP address was already stable in the cache, and no packet is
00879  * given, an ARP request is sent out.
00880  * 
00881  * @param netif The lwIP network interface on which ipaddr
00882  * must be queried for.
00883  * @param ipaddr The IP address to be resolved.
00884  * @param q If non-NULL, a pbuf that must be delivered to the IP address.
00885  * q is not freed by this function.
00886  *
00887  * @note q must only be ONE packet, not a packet queue!
00888  *
00889  * @return
00890  * - ERR_BUF Could not make room for Ethernet header.
00891  * - ERR_MEM Hardware address unknown, and no more ARP entries available
00892  *   to query for address or queue the packet.
00893  * - ERR_MEM Could not queue packet due to memory shortage.
00894  * - ERR_RTE No route to destination (no gateway to external networks).
00895  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00896  *
00897  */
00898 err_t
00899 etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
00900 {
00901   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
00902   err_t result = ERR_MEM;
00903   s8_t i; /* ARP entry index */
00904 
00905   /* non-unicast address? */
00906   if (ip_addr_isbroadcast(ipaddr, netif) ||
00907       ip_addr_ismulticast(ipaddr) ||
00908       ip_addr_isany(ipaddr)) {
00909     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
00910     return ERR_ARG;
00911   }
00912 
00913   /* find entry in ARP cache, ask to create entry if queueing packet */
00914 #if LWIP_NETIF_HWADDRHINT
00915   i = find_entry(ipaddr, ETHARP_TRY_HARD, netif);
00916 #else /* LWIP_NETIF_HWADDRHINT */
00917   i = find_entry(ipaddr, ETHARP_TRY_HARD);
00918 #endif /* LWIP_NETIF_HWADDRHINT */
00919 
00920   /* could not find or create entry? */
00921   if (i < 0) {
00922     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
00923     if (q) {
00924       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
00925       ETHARP_STATS_INC(etharp.memerr);
00926     }
00927     return (err_t)i;
00928   }
00929 
00930   /* mark a fresh entry as pending (we just sent a request) */
00931   if (arp_table[i].state == ETHARP_STATE_EMPTY) {
00932     arp_table[i].state = ETHARP_STATE_PENDING;
00933   }
00934 
00935   /* { i is either a STABLE or (new or existing) PENDING entry } */
00936   LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
00937   ((arp_table[i].state == ETHARP_STATE_PENDING) ||
00938    (arp_table[i].state == ETHARP_STATE_STABLE)));
00939 
00940   /* do we have a pending entry? or an implicit query request? */
00941   if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
00942     /* try to resolve it; send out ARP request */
00943     result = etharp_request(netif, ipaddr);
00944     if (result != ERR_OK) {
00945       /* ARP request couldn't be sent */
00946       /* We don't re-send arp request in etharp_tmr, but we still queue packets,
00947          since this failure could be temporary, and the next packet calling
00948          etharp_query again could lead to sending the queued packets. */
00949     }
00950   }
00951   
00952   /* packet given? */
00953   if (q != NULL) {
00954     /* stable entry? */
00955     if (arp_table[i].state == ETHARP_STATE_STABLE) {
00956       /* we have a valid IP->Ethernet address mapping */
00957       /* send the packet */
00958       result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
00959     /* pending entry? (either just created or already pending */
00960     } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
00961 #if ARP_QUEUEING /* queue the given q packet */
00962       struct pbuf *p;
00963       int copy_needed = 0;
00964       /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
00965        * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
00966        * PBUF_ROMs can be left as they are, since ROM must not get changed. */
00967       p = q;
00968       while (p) {
00969         LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
00970         if(p->type != PBUF_ROM) {
00971           copy_needed = 1;
00972           break;
00973         }
00974         p = p->next;
00975       }
00976       if(copy_needed) {
00977         /* copy the whole packet into new pbufs */
00978         p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
00979         if(p != NULL) {
00980           if (pbuf_copy(p, q) != ERR_OK) {
00981             pbuf_free(p);
00982             p = NULL;
00983           }
00984         }
00985       } else {
00986         /* referencing the old pbuf is enough */
00987         p = q;
00988         pbuf_ref(p);
00989       }
00990       /* packet could be taken over? */
00991       if (p != NULL) {
00992         /* queue packet ... */
00993         struct etharp_q_entry *new_entry;
00994         /* allocate a new arp queue entry */
00995         new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
00996         if (new_entry != NULL) {
00997           new_entry->next = 0;
00998           new_entry->p = p;
00999           if(arp_table[i].q != NULL) {
01000             /* queue was already existent, append the new entry to the end */
01001             struct etharp_q_entry *r;
01002             r = arp_table[i].q;
01003             while (r->next != NULL) {
01004               r = r->next;
01005             }
01006             r->next = new_entry;
01007           } else {
01008             /* queue did not exist, first item in queue */
01009             arp_table[i].q = new_entry;
01010           }
01011           LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01012           result = ERR_OK;
01013         } else {
01014           /* the pool MEMP_ARP_QUEUE is empty */
01015           pbuf_free(p);
01016           LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
01017           /* { result == ERR_MEM } through initialization */
01018         }
01019       } else {
01020         ETHARP_STATS_INC(etharp.memerr);
01021         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
01022         /* { result == ERR_MEM } through initialization */
01023       }
01024 #else /* ARP_QUEUEING */
01025       /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
01026       /* { result == ERR_MEM } through initialization */
01027       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
01028 #endif /* ARP_QUEUEING */
01029     }
01030   }
01031   return result;
01032 }
01033 
01034 /**
01035  * Send a raw ARP packet (opcode and all addresses can be modified)
01036  *
01037  * @param netif the lwip network interface on which to send the ARP packet
01038  * @param ethsrc_addr the source MAC address for the ethernet header
01039  * @param ethdst_addr the destination MAC address for the ethernet header
01040  * @param hwsrc_addr the source MAC address for the ARP protocol header
01041  * @param ipsrc_addr the source IP address for the ARP protocol header
01042  * @param hwdst_addr the destination MAC address for the ARP protocol header
01043  * @param ipdst_addr the destination IP address for the ARP protocol header
01044  * @param opcode the type of the ARP packet
01045  * @return ERR_OK if the ARP packet has been sent
01046  *         ERR_MEM if the ARP packet couldn't be allocated
01047  *         any other err_t on failure
01048  */
01049 #if !LWIP_AUTOIP
01050 static
01051 #endif /* LWIP_AUTOIP */
01052 err_t
01053 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
01054            const struct eth_addr *ethdst_addr,
01055            const struct eth_addr *hwsrc_addr, const ip_addr_t *ipsrc_addr,
01056            const struct eth_addr *hwdst_addr, const ip_addr_t *ipdst_addr,
01057            const u16_t opcode)
01058 {
01059   struct pbuf *p;
01060   err_t result = ERR_OK;
01061   u8_t k; /* ARP entry index */
01062   struct eth_hdr *ethhdr;
01063   struct etharp_hdr *hdr;
01064 #if LWIP_AUTOIP
01065   const u8_t * ethdst_hwaddr;
01066 #endif /* LWIP_AUTOIP */
01067 
01068   /* allocate a pbuf for the outgoing ARP request packet */
01069   p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
01070   /* could allocate a pbuf for an ARP request? */
01071   if (p == NULL) {
01072     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
01073       ("etharp_raw: could not allocate pbuf for ARP request.\n"));
01074     ETHARP_STATS_INC(etharp.memerr);
01075     return ERR_MEM;
01076   }
01077   LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
01078               (p->len >= SIZEOF_ETHARP_PACKET));
01079 
01080   ethhdr = (struct eth_hdr *)p->payload;
01081   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
01082   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
01083   hdr->opcode = htons(opcode);
01084 
01085   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
01086               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
01087   k = ETHARP_HWADDR_LEN;
01088 #if LWIP_AUTOIP
01089   /* If we are using Link-Local, all ARP packets that contain a Link-Local
01090    * 'sender IP address' MUST be sent using link-layer broadcast instead of
01091    * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
01092   ethdst_hwaddr = ip_addr_islinklocal(ipsrc_addr) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
01093 #endif /* LWIP_AUTOIP */
01094   /* Write MAC-Addresses (combined loop for both headers) */
01095   while(k > 0) {
01096     k--;
01097     /* Write the ARP MAC-Addresses */
01098     hdr->shwaddr.addr[k] = hwsrc_addr->addr[k];
01099     hdr->dhwaddr.addr[k] = hwdst_addr->addr[k];
01100     /* Write the Ethernet MAC-Addresses */
01101 #if LWIP_AUTOIP
01102     ethhdr->dest.addr[k] = ethdst_hwaddr[k];
01103 #else  /* LWIP_AUTOIP */
01104     ethhdr->dest.addr[k] = ethdst_addr->addr[k];
01105 #endif /* LWIP_AUTOIP */
01106     ethhdr->src.addr[k]  = ethsrc_addr->addr[k];
01107   }
01108   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
01109    * structure packing. */ 
01110   SMEMCPY(&hdr->sipaddr, ipsrc_addr, sizeof(ip_addr_t));
01111   SMEMCPY(&hdr->dipaddr, ipdst_addr, sizeof(ip_addr_t));
01112 
01113   hdr->hwtype = htons(HWTYPE_ETHERNET);
01114   hdr->proto = htons(ETHTYPE_IP);
01115   /* set hwlen and protolen together */
01116   hdr->_hwlen_protolen = htons((ETHARP_HWADDR_LEN << 8) | sizeof(ip_addr_t));
01117 
01118   ethhdr->type = htons(ETHTYPE_ARP);
01119   /* send ARP query */
01120   result = netif->linkoutput(netif, p);
01121   ETHARP_STATS_INC(etharp.xmit);
01122   /* free ARP query packet */
01123   pbuf_free(p);
01124   p = NULL;
01125   /* could not allocate pbuf for ARP request */
01126 
01127   return result;
01128 }
01129 
01130 /**
01131  * Send an ARP request packet asking for ipaddr.
01132  *
01133  * @param netif the lwip network interface on which to send the request
01134  * @param ipaddr the IP address for which to ask
01135  * @return ERR_OK if the request has been sent
01136  *         ERR_MEM if the ARP packet couldn't be allocated
01137  *         any other err_t on failure
01138  */
01139 err_t
01140 etharp_request(struct netif *netif, ip_addr_t *ipaddr)
01141 {
01142   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
01143   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
01144                     (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
01145                     ipaddr, ARP_REQUEST);
01146 }
01147 #endif /* LWIP_ARP */
01148 
01149 /**
01150  * Process received ethernet frames. Using this function instead of directly
01151  * calling ip_input and passing ARP frames through etharp in ethernetif_input,
01152  * the ARP cache is protected from concurrent access.
01153  *
01154  * @param p the recevied packet, p->payload pointing to the ethernet header
01155  * @param netif the network interface on which the packet was received
01156  */
01157 err_t
01158 ethernet_input(struct pbuf *p, struct netif *netif)
01159 {
01160   struct eth_hdr* ethhdr;
01161   u16_t type;
01162 
01163   /* points to packet payload, which starts with an Ethernet header */
01164   ethhdr = (struct eth_hdr *)p->payload;
01165   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
01166     ("ethernet_input: dest:%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F", src:%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F", type:%"X16_F"\n",
01167      (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
01168      (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
01169      (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
01170      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
01171      (unsigned)htons(ethhdr->type)));
01172 
01173   type = htons(ethhdr->type);
01174 #if ETHARP_SUPPORT_VLAN
01175   if (type == ETHTYPE_VLAN) {
01176     struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
01177 #ifdef ETHARP_VLAN_CHECK /* if not, allow all VLANs */
01178     if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
01179       /* silently ignore this packet: not for our VLAN */
01180       pbuf_free(p);
01181       return ERR_OK;
01182     }
01183 #endif /* ETHARP_VLAN_CHECK */
01184     type = htons(vlan->tpid);
01185   }
01186 #endif /* ETHARP_SUPPORT_VLAN */
01187 
01188   switch (type) {
01189 #if LWIP_ARP
01190     /* IP packet? */
01191     case ETHTYPE_IP:
01192       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01193         goto free_and_return;
01194       }
01195 #if ETHARP_TRUST_IP_MAC
01196       /* update ARP table */
01197       etharp_ip_input(netif, p);
01198 #endif /* ETHARP_TRUST_IP_MAC */
01199       /* skip Ethernet header */
01200       if(pbuf_header(p, -(s16_t)SIZEOF_ETH_HDR)) {
01201         LWIP_ASSERT("Can't move over header in packet", 0);
01202         goto free_and_return;
01203       } else {
01204         /* pass to IP layer */
01205         ip_input(p, netif);
01206       }
01207       break;
01208       
01209     case ETHTYPE_ARP:
01210       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01211         goto free_and_return;
01212       }
01213       /* pass p to ARP module */
01214       etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
01215       break;
01216 #endif /* LWIP_ARP */
01217 #if PPPOE_SUPPORT
01218     case ETHTYPE_PPPOEDISC: /* PPP Over Ethernet Discovery Stage */
01219       pppoe_disc_input(netif, p);
01220       break;
01221 
01222     case ETHTYPE_PPPOE: /* PPP Over Ethernet Session Stage */
01223       pppoe_data_input(netif, p);
01224       break;
01225 #endif /* PPPOE_SUPPORT */
01226 
01227     default:
01228       ETHARP_STATS_INC(etharp.proterr);
01229       ETHARP_STATS_INC(etharp.drop);
01230       goto free_and_return;
01231   }
01232 
01233   /* This means the pbuf is freed or consumed,
01234      so the caller doesn't have to free it again */
01235   return ERR_OK;
01236 
01237 free_and_return:
01238   pbuf_free(p);
01239   return ERR_OK;
01240 }
01241 #endif /* LWIP_ARP || LWIP_ETHERNET */