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 enum etharp_state {
00087   ETHARP_STATE_EMPTY = 0,
00088   ETHARP_STATE_PENDING,
00089   ETHARP_STATE_STABLE
00090 };
00091 
00092 struct etharp_entry {
00093 #if ARP_QUEUEING
00094   /** Pointer to queue of pending outgoing packets on this ARP entry. */
00095   struct etharp_q_entry *q;
00096 #else /* ARP_QUEUEING */
00097   /** Pointer to a single pending outgoing packet on this ARP entry. */
00098   struct pbuf *q;
00099 #endif /* ARP_QUEUEING */
00100   ip_addr_t ipaddr;
00101   struct eth_addr ethaddr;
00102 #if LWIP_SNMP
00103   struct netif *netif;
00104 #endif /* LWIP_SNMP */
00105   u8_t state;
00106   u8_t ctime;
00107 #if ETHARP_SUPPORT_STATIC_ENTRIES
00108   u8_t static_entry;
00109 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00110 };
00111 
00112 static struct etharp_entry arp_table[ARP_TABLE_SIZE];
00113 
00114 #if !LWIP_NETIF_HWADDRHINT
00115 static u8_t etharp_cached_entry;
00116 #endif /* !LWIP_NETIF_HWADDRHINT */
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_FLAG_TRY_HARD     1
00121 #define ETHARP_FLAG_FIND_ONLY    2
00122 #define ETHARP_FLAG_STATIC_ENTRY 4
00123 
00124 #if LWIP_NETIF_HWADDRHINT
00125 #define ETHARP_SET_HINT(netif, hint)  if (((netif) != NULL) && ((netif)->addr_hint != NULL))  \
00126                                       *((netif)->addr_hint) = (hint);
00127 #else /* LWIP_NETIF_HWADDRHINT */
00128 #define ETHARP_SET_HINT(netif, hint)  (etharp_cached_entry = (hint))
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 "ARP_TABLE_SIZE must fit in an s8_t, 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 #else /* ARP_QUEUEING */
00161 
00162 /** Compatibility define: free the queued pbuf */
00163 #define free_etharp_q(q) pbuf_free(q)
00164 
00165 #endif /* ARP_QUEUEING */
00166 
00167 /** Clean up ARP table entries */
00168 static void
00169 free_entry(int i)
00170 {
00171   /* remove from SNMP ARP index tree */
00172   snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00173   /* and empty packet queue */
00174   if (arp_table[i].q != NULL) {
00175     /* remove all queued packets */
00176     LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
00177     free_etharp_q(arp_table[i].q);
00178     arp_table[i].q = NULL;
00179   }
00180   /* recycle entry for re-use */      
00181   arp_table[i].state = ETHARP_STATE_EMPTY;
00182 #if ETHARP_SUPPORT_STATIC_ENTRIES
00183   arp_table[i].static_entry = 0;
00184 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00185 #ifdef LWIP_DEBUG
00186   /* for debugging, clean out the complete entry */
00187   arp_table[i].ctime = 0;
00188 #if LWIP_SNMP
00189   arp_table[i].netif = NULL;
00190 #endif /* LWIP_SNMP */
00191   ip_addr_set_zero(&arp_table[i].ipaddr);
00192   arp_table[i].ethaddr = ethzero;
00193 #endif /* LWIP_DEBUG */
00194 }
00195 
00196 /**
00197  * Clears expired entries in the ARP table.
00198  *
00199  * This function should be called every ETHARP_TMR_INTERVAL milliseconds (5 seconds),
00200  * in order to expire entries in the ARP table.
00201  */
00202 void
00203 etharp_tmr(void)
00204 {
00205   u8_t i;
00206 
00207   LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
00208   /* remove expired entries from the ARP table */
00209   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00210     u8_t state = arp_table[i].state;
00211     if (state != ETHARP_STATE_EMPTY
00212 #if ETHARP_SUPPORT_STATIC_ENTRIES
00213       && (arp_table[i].static_entry == 0)
00214 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00215       ) {
00216       arp_table[i].ctime++;
00217       if ((arp_table[i].ctime >= ARP_MAXAGE) ||
00218           ((arp_table[i].state == ETHARP_STATE_PENDING)  &&
00219            (arp_table[i].ctime >= ARP_MAXPENDING))) {
00220         /* pending or stable entry has become old! */
00221         LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
00222              arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
00223         /* clean up entries that have just been expired */
00224         free_entry(i);
00225       }
00226 #if ARP_QUEUEING
00227       /* still pending entry? (not expired) */
00228       if (arp_table[i].state == ETHARP_STATE_PENDING) {
00229         /* resend an ARP query here? */
00230       }
00231 #endif /* ARP_QUEUEING */
00232     }
00233   }
00234 }
00235 
00236 /**
00237  * Search the ARP table for a matching or new entry.
00238  * 
00239  * If an IP address is given, return a pending or stable ARP entry that matches
00240  * the address. If no match is found, create a new entry with this address set,
00241  * but in state ETHARP_EMPTY. The caller must check and possibly change the
00242  * state of the returned entry.
00243  * 
00244  * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
00245  * 
00246  * In all cases, attempt to create new entries from an empty entry. If no
00247  * empty entries are available and ETHARP_FLAG_TRY_HARD flag is set, recycle
00248  * old entries. Heuristic choose the least important entry for recycling.
00249  *
00250  * @param ipaddr IP address to find in ARP cache, or to add if not found.
00251  * @param flags @see definition of ETHARP_FLAG_*
00252  * @param netif netif related to this address (used for NETIF_HWADDRHINT)
00253  *  
00254  * @return The ARP entry index that matched or is created, ERR_MEM if no
00255  * entry is found or could be recycled.
00256  */
00257 static s8_t
00258 find_entry(ip_addr_t *ipaddr, u8_t flags)
00259 {
00260   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
00261   s8_t empty = ARP_TABLE_SIZE;
00262   u8_t i = 0, age_pending = 0, age_stable = 0;
00263   /* oldest entry with packets on queue */
00264   s8_t old_queue = ARP_TABLE_SIZE;
00265   /* its age */
00266   u8_t age_queue = 0;
00267 
00268   /**
00269    * a) do a search through the cache, remember candidates
00270    * b) select candidate entry
00271    * c) create new entry
00272    */
00273 
00274   /* a) in a single search sweep, do all of this
00275    * 1) remember the first empty entry (if any)
00276    * 2) remember the oldest stable entry (if any)
00277    * 3) remember the oldest pending entry without queued packets (if any)
00278    * 4) remember the oldest pending entry with queued packets (if any)
00279    * 5) search for a matching IP entry, either pending or stable
00280    *    until 5 matches, or all entries are searched for.
00281    */
00282 
00283   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00284     u8_t state = arp_table[i].state;
00285     /* no empty entry found yet and now we do find one? */
00286     if ((empty == ARP_TABLE_SIZE) && (state == ETHARP_STATE_EMPTY)) {
00287       LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
00288       /* remember first empty entry */
00289       empty = i;
00290     } else if (state != ETHARP_STATE_EMPTY) {
00291       LWIP_ASSERT("state == ETHARP_STATE_PENDING || state == ETHARP_STATE_STABLE",
00292         state == ETHARP_STATE_PENDING || state == ETHARP_STATE_STABLE);
00293       /* if given, does IP address match IP address in ARP entry? */
00294       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00295         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching entry %"U16_F"\n", (u16_t)i));
00296         /* found exact IP address match, simply bail out */
00297         return i;
00298       }
00299       /* pending entry? */
00300       if (state == ETHARP_STATE_PENDING) {
00301         /* pending with queued packets? */
00302         if (arp_table[i].q != NULL) {
00303           if (arp_table[i].ctime >= age_queue) {
00304             old_queue = i;
00305             age_queue = arp_table[i].ctime;
00306           }
00307         } else
00308         /* pending without queued packets? */
00309         {
00310           if (arp_table[i].ctime >= age_pending) {
00311             old_pending = i;
00312             age_pending = arp_table[i].ctime;
00313           }
00314         }
00315       /* stable entry? */
00316       } else if (state == ETHARP_STATE_STABLE) {
00317 #if ETHARP_SUPPORT_STATIC_ENTRIES
00318         /* don't record old_stable for static entries since they never expire */
00319         if (arp_table[i].static_entry == 0)
00320 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00321         {
00322           /* remember entry with oldest stable entry in oldest, its age in maxtime */
00323           if (arp_table[i].ctime >= age_stable) {
00324             old_stable = i;
00325             age_stable = arp_table[i].ctime;
00326           }
00327         }
00328       }
00329     }
00330   }
00331   /* { we have no match } => try to create a new entry */
00332    
00333   /* don't create new entry, only search? */
00334   if (((flags & ETHARP_FLAG_FIND_ONLY) != 0) ||
00335       /* or no empty entry found and not allowed to recycle? */
00336       ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_FLAG_TRY_HARD) == 0))) {
00337     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
00338     return (s8_t)ERR_MEM;
00339   }
00340   
00341   /* b) choose the least destructive entry to recycle:
00342    * 1) empty entry
00343    * 2) oldest stable entry
00344    * 3) oldest pending entry without queued packets
00345    * 4) oldest pending entry with queued packets
00346    * 
00347    * { ETHARP_FLAG_TRY_HARD is set at this point }
00348    */ 
00349 
00350   /* 1) empty entry available? */
00351   if (empty < ARP_TABLE_SIZE) {
00352     i = empty;
00353     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
00354   } else {
00355     /* 2) found recyclable stable entry? */
00356     if (old_stable < ARP_TABLE_SIZE) {
00357       /* recycle oldest stable*/
00358       i = old_stable;
00359       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
00360       /* no queued packets should exist on stable entries */
00361       LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
00362     /* 3) found recyclable pending entry without queued packets? */
00363     } else if (old_pending < ARP_TABLE_SIZE) {
00364       /* recycle oldest pending */
00365       i = old_pending;
00366       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
00367     /* 4) found recyclable pending entry with queued packets? */
00368     } else if (old_queue < ARP_TABLE_SIZE) {
00369       /* recycle oldest pending (queued packets are free in free_entry) */
00370       i = old_queue;
00371       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)));
00372       /* no empty or recyclable entries found */
00373     } else {
00374       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty or recyclable entries found\n"));
00375       return (s8_t)ERR_MEM;
00376     }
00377 
00378     /* { empty or recyclable entry found } */
00379     LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00380     free_entry(i);
00381   }
00382 
00383   LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00384   LWIP_ASSERT("arp_table[i].state == ETHARP_STATE_EMPTY",
00385     arp_table[i].state == ETHARP_STATE_EMPTY);
00386 
00387   /* IP address given? */
00388   if (ipaddr != NULL) {
00389     /* set IP address */
00390     ip_addr_copy(arp_table[i].ipaddr, *ipaddr);
00391   }
00392   arp_table[i].ctime = 0;
00393 #if ETHARP_SUPPORT_STATIC_ENTRIES
00394   arp_table[i].static_entry = 0;
00395 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00396   return (err_t)i;
00397 }
00398 
00399 /**
00400  * Send an IP packet on the network using netif->linkoutput
00401  * The ethernet header is filled in before sending.
00402  *
00403  * @params netif the lwIP network interface on which to send the packet
00404  * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
00405  * @params src the source MAC address to be copied into the ethernet header
00406  * @params dst the destination MAC address to be copied into the ethernet header
00407  * @return ERR_OK if the packet was sent, any other err_t on failure
00408  */
00409 static err_t
00410 etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
00411 {
00412   struct eth_hdr *ethhdr = (struct eth_hdr *)p->payload;
00413 
00414   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00415               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00416   ETHADDR32_COPY(&ethhdr->dest, dst);
00417   ETHADDR16_COPY(&ethhdr->src, src);
00418   ethhdr->type = PP_HTONS(ETHTYPE_IP);
00419   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
00420   /* send the packet */
00421   return netif->linkoutput(netif, p);
00422 }
00423 
00424 /**
00425  * Update (or insert) a IP/MAC address pair in the ARP cache.
00426  *
00427  * If a pending entry is resolved, any queued packets will be sent
00428  * at this point.
00429  * 
00430  * @param netif netif related to this entry (used for NETIF_ADDRHINT)
00431  * @param ipaddr IP address of the inserted ARP entry.
00432  * @param ethaddr Ethernet address of the inserted ARP entry.
00433  * @param flags @see definition of ETHARP_FLAG_*
00434  *
00435  * @return
00436  * - ERR_OK Succesfully updated ARP cache.
00437  * - ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set.
00438  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00439  *
00440  * @see pbuf_free()
00441  */
00442 static err_t
00443 update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
00444 {
00445   s8_t i;
00446   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
00447   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",
00448     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00449     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00450     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00451   /* non-unicast address? */
00452   if (ip_addr_isany(ipaddr) ||
00453       ip_addr_isbroadcast(ipaddr, netif) ||
00454       ip_addr_ismulticast(ipaddr)) {
00455     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
00456     return ERR_ARG;
00457   }
00458   /* find or create ARP entry */
00459   i = find_entry(ipaddr, flags);
00460   /* bail out if no entry could be found */
00461   if (i < 0) {
00462     return (err_t)i;
00463   }
00464 
00465 #if ETHARP_SUPPORT_STATIC_ENTRIES
00466   if (flags & ETHARP_FLAG_STATIC_ENTRY) {
00467     /* record static type */
00468     arp_table[i].static_entry = 1;
00469   }
00470 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00471 
00472   /* mark it stable */
00473   arp_table[i].state = ETHARP_STATE_STABLE;
00474 
00475 #if LWIP_SNMP
00476   /* record network interface */
00477   arp_table[i].netif = netif;
00478 #endif /* LWIP_SNMP */
00479   /* insert in SNMP ARP index tree */
00480   snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
00481 
00482   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
00483   /* update address */
00484   ETHADDR32_COPY(&arp_table[i].ethaddr, ethaddr);
00485   /* reset time stamp */
00486   arp_table[i].ctime = 0;
00487   /* this is where we will send out queued packets! */
00488 #if ARP_QUEUEING
00489   while (arp_table[i].q != NULL) {
00490     struct pbuf *p;
00491     /* remember remainder of queue */
00492     struct etharp_q_entry *q = arp_table[i].q;
00493     /* pop first item off the queue */
00494     arp_table[i].q = q->next;
00495     /* get the packet pointer */
00496     p = q->p;
00497     /* now queue entry can be freed */
00498     memp_free(MEMP_ARP_QUEUE, q);
00499 #else /* ARP_QUEUEING */
00500   if (arp_table[i].q != NULL) {
00501     struct pbuf *p = arp_table[i].q;
00502     arp_table[i].q = NULL;
00503 #endif /* ARP_QUEUEING */
00504     /* send the queued IP packet */
00505     etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
00506     /* free the queued IP packet */
00507     pbuf_free(p);
00508   }
00509   return ERR_OK;
00510 }
00511 
00512 #if ETHARP_SUPPORT_STATIC_ENTRIES
00513 /** Add a new static entry to the ARP table. If an entry exists for the
00514  * specified IP address, this entry is overwritten.
00515  * If packets are queued for the specified IP address, they are sent out.
00516  *
00517  * @param ipaddr IP address for the new static entry
00518  * @param ethaddr ethernet address for the new static entry
00519  * @return @see return values of etharp_add_static_entry
00520  */
00521 err_t
00522 etharp_add_static_entry(ip_addr_t *ipaddr, struct eth_addr *ethaddr)
00523 {
00524   struct netif *netif;
00525   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_add_static_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",
00526     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00527     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00528     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00529 
00530   netif = ip_route(ipaddr);
00531   if (netif == NULL) {
00532     return ERR_RTE;
00533   }
00534 
00535   return update_arp_entry(netif, ipaddr, ethaddr, ETHARP_FLAG_TRY_HARD | ETHARP_FLAG_STATIC_ENTRY);
00536 }
00537 
00538 /** Remove a static entry from the ARP table previously added with a call to
00539  * etharp_add_static_entry.
00540  *
00541  * @param ipaddr IP address of the static entry to remove
00542  * @return ERR_OK: entry removed
00543  *         ERR_MEM: entry wasn't found
00544  *         ERR_ARG: entry wasn't a static entry but a dynamic one
00545  */
00546 err_t
00547 etharp_remove_static_entry(ip_addr_t *ipaddr)
00548 {
00549   s8_t i;
00550   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00551     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
00552 
00553   /* find or create ARP entry */
00554   i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
00555   /* bail out if no entry could be found */
00556   if (i < 0) {
00557     return (err_t)i;
00558   }
00559 
00560   if ((arp_table[i].state != ETHARP_STATE_STABLE) ||
00561     (arp_table[i].static_entry == 0)) {
00562     /* entry wasn't a static entry, cannot remove it */
00563     return ERR_ARG;
00564   }
00565   /* entry found, free it */
00566   free_entry(i);
00567   return ERR_OK;
00568 }
00569 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00570 
00571 /**
00572  * Finds (stable) ethernet/IP address pair from ARP table
00573  * using interface and IP address index.
00574  * @note the addresses in the ARP table are in network order!
00575  *
00576  * @param netif points to interface index
00577  * @param ipaddr points to the (network order) IP address index
00578  * @param eth_ret points to return pointer
00579  * @param ip_ret points to return pointer
00580  * @return table index if found, -1 otherwise
00581  */
00582 s8_t
00583 etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
00584          struct eth_addr **eth_ret, ip_addr_t **ip_ret)
00585 {
00586   s8_t i;
00587 
00588   LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL",
00589     eth_ret != NULL && ip_ret != NULL);
00590 
00591   LWIP_UNUSED_ARG(netif);
00592 
00593   i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
00594   if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) {
00595       *eth_ret = &arp_table[i].ethaddr;
00596       *ip_ret = &arp_table[i].ipaddr;
00597       return i;
00598   }
00599   return -1;
00600 }
00601 
00602 #if ETHARP_TRUST_IP_MAC
00603 /**
00604  * Updates the ARP table using the given IP packet.
00605  *
00606  * Uses the incoming IP packet's source address to update the
00607  * ARP cache for the local network. The function does not alter
00608  * or free the packet. This function must be called before the
00609  * packet p is passed to the IP layer.
00610  *
00611  * @param netif The lwIP network interface on which the IP packet pbuf arrived.
00612  * @param p The IP packet that arrived on netif.
00613  *
00614  * @return NULL
00615  *
00616  * @see pbuf_free()
00617  */
00618 static void
00619 etharp_ip_input(struct netif *netif, struct pbuf *p)
00620 {
00621   struct eth_hdr *ethhdr;
00622   struct ip_hdr *iphdr;
00623   ip_addr_t iphdr_src;
00624   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00625 
00626   /* Only insert an entry if the source IP address of the
00627      incoming IP packet comes from a host on the local network. */
00628   ethhdr = (struct eth_hdr *)p->payload;
00629   iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00630 #if ETHARP_SUPPORT_VLAN
00631   if (ethhdr->type == PP_HTONS(ETHTYPE_VLAN)) {
00632     iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00633   }
00634 #endif /* ETHARP_SUPPORT_VLAN */
00635 
00636   ip_addr_copy(iphdr_src, iphdr->src);
00637 
00638   /* source is not on the local network? */
00639   if (!ip_addr_netcmp(&iphdr_src, &(netif->ip_addr), &(netif->netmask))) {
00640     /* do nothing */
00641     return;
00642   }
00643 
00644   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
00645   /* update the source IP address in the cache, if present */
00646   /* @todo We could use ETHARP_FLAG_TRY_HARD if we think we are going to talk
00647    * back soon (for example, if the destination IP address is ours. */
00648   update_arp_entry(netif, &iphdr_src, &(ethhdr->src), ETHARP_FLAG_FIND_ONLY);
00649 }
00650 #endif /* ETHARP_TRUST_IP_MAC */
00651 
00652 /**
00653  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
00654  * send out queued IP packets. Updates cache with snooped address pairs.
00655  *
00656  * Should be called for incoming ARP packets. The pbuf in the argument
00657  * is freed by this function.
00658  *
00659  * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
00660  * @param ethaddr Ethernet address of netif.
00661  * @param p The ARP packet that arrived on netif. Is freed by this function.
00662  *
00663  * @return NULL
00664  *
00665  * @see pbuf_free()
00666  */
00667 static void
00668 etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
00669 {
00670   struct etharp_hdr *hdr;
00671   struct eth_hdr *ethhdr;
00672   /* these are aligned properly, whereas the ARP header fields might not be */
00673   ip_addr_t sipaddr, dipaddr;
00674   u8_t for_us;
00675 #if LWIP_AUTOIP
00676   const u8_t * ethdst_hwaddr;
00677 #endif /* LWIP_AUTOIP */
00678 
00679   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00680 
00681   /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
00682      since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
00683   if (p->len < SIZEOF_ETHARP_PACKET) {
00684     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00685       ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len,
00686       (s16_t)SIZEOF_ETHARP_PACKET));
00687     ETHARP_STATS_INC(etharp.lenerr);
00688     ETHARP_STATS_INC(etharp.drop);
00689     pbuf_free(p);
00690     return;
00691   }
00692 
00693   ethhdr = (struct eth_hdr *)p->payload;
00694   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00695 #if ETHARP_SUPPORT_VLAN
00696   if (ethhdr->type == PP_HTONS(ETHTYPE_VLAN)) {
00697     hdr = (struct etharp_hdr *)(((u8_t*)ethhdr) + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00698   }
00699 #endif /* ETHARP_SUPPORT_VLAN */
00700 
00701   /* RFC 826 "Packet Reception": */
00702   if ((hdr->hwtype != PP_HTONS(HWTYPE_ETHERNET)) ||
00703       (hdr->hwlen != ETHARP_HWADDR_LEN) ||
00704       (hdr->protolen != sizeof(ip_addr_t)) ||
00705       (hdr->proto != PP_HTONS(ETHTYPE_IP)))  {
00706     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00707       ("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
00708       hdr->hwtype, hdr->hwlen, hdr->proto, hdr->protolen));
00709     ETHARP_STATS_INC(etharp.proterr);
00710     ETHARP_STATS_INC(etharp.drop);
00711     pbuf_free(p);
00712     return;
00713   }
00714   ETHARP_STATS_INC(etharp.recv);
00715 
00716 #if LWIP_AUTOIP
00717   /* We have to check if a host already has configured our random
00718    * created link local address and continously check if there is
00719    * a host with this IP-address so we can detect collisions */
00720   autoip_arp_reply(netif, hdr);
00721 #endif /* LWIP_AUTOIP */
00722 
00723   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00724    * structure packing (not using structure copy which breaks strict-aliasing rules). */
00725   IPADDR2_COPY(&sipaddr, &hdr->sipaddr);
00726   IPADDR2_COPY(&dipaddr, &hdr->dipaddr);
00727 
00728   /* this interface is not configured? */
00729   if (ip_addr_isany(&netif->ip_addr)) {
00730     for_us = 0;
00731   } else {
00732     /* ARP packet directed to us? */
00733     for_us = (u8_t)ip_addr_cmp(&dipaddr, &(netif->ip_addr));
00734   }
00735 
00736   /* ARP message directed to us?
00737       -> add IP address in ARP cache; assume requester wants to talk to us,
00738          can result in directly sending the queued packets for this host.
00739      ARP message not directed to us?
00740       ->  update the source IP address in the cache, if present */
00741   update_arp_entry(netif, &sipaddr, &(hdr->shwaddr),
00742                    for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY);
00743 
00744   /* now act on the message itself */
00745   switch (hdr->opcode) {
00746   /* ARP request? */
00747   case PP_HTONS(ARP_REQUEST):
00748     /* ARP request. If it asked for our address, we send out a
00749      * reply. In any case, we time-stamp any existing ARP entry,
00750      * and possiby send out an IP packet that was queued on it. */
00751 
00752     LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
00753     /* ARP request for our address? */
00754     if (for_us) {
00755 
00756       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
00757       /* Re-use pbuf to send ARP reply.
00758          Since we are re-using an existing pbuf, we can't call etharp_raw since
00759          that would allocate a new pbuf. */
00760       hdr->opcode = htons(ARP_REPLY);
00761 
00762       IPADDR2_COPY(&hdr->dipaddr, &hdr->sipaddr);
00763       IPADDR2_COPY(&hdr->sipaddr, &netif->ip_addr);
00764 
00765       LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00766                   (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00767 #if LWIP_AUTOIP
00768       /* If we are using Link-Local, all ARP packets that contain a Link-Local
00769        * 'sender IP address' MUST be sent using link-layer broadcast instead of
00770        * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
00771       ethdst_hwaddr = ip_addr_islinklocal(&netif->ip_addr) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
00772 #endif /* LWIP_AUTOIP */
00773 
00774       ETHADDR16_COPY(&hdr->dhwaddr, &hdr->shwaddr);
00775 #if LWIP_AUTOIP
00776       ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
00777 #else  /* LWIP_AUTOIP */
00778       ETHADDR16_COPY(&ethhdr->dest, &hdr->shwaddr);
00779 #endif /* LWIP_AUTOIP */
00780       ETHADDR16_COPY(&hdr->shwaddr, ethaddr);
00781       ETHADDR16_COPY(&ethhdr->src, ethaddr);
00782 
00783       /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
00784          are already correct, we tested that before */
00785 
00786       /* return ARP reply */
00787       netif->linkoutput(netif, p);
00788     /* we are not configured? */
00789     } else if (ip_addr_isany(&netif->ip_addr)) {
00790       /* { for_us == 0 and netif->ip_addr.addr == 0 } */
00791       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
00792     /* request was not directed to us */
00793     } else {
00794       /* { for_us == 0 and netif->ip_addr.addr != 0 } */
00795       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
00796     }
00797     break;
00798   case PP_HTONS(ARP_REPLY):
00799     /* ARP reply. We already updated the ARP cache earlier. */
00800     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
00801 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
00802     /* DHCP wants to know about ARP replies from any host with an
00803      * IP address also offered to us by the DHCP server. We do not
00804      * want to take a duplicate IP address on a single network.
00805      * @todo How should we handle redundant (fail-over) interfaces? */
00806     dhcp_arp_reply(netif, &sipaddr);
00807 #endif /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */
00808     break;
00809   default:
00810     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
00811     ETHARP_STATS_INC(etharp.err);
00812     break;
00813   }
00814   /* free ARP packet */
00815   pbuf_free(p);
00816 }
00817 
00818 /**
00819  * Resolve and fill-in Ethernet address header for outgoing IP packet.
00820  *
00821  * For IP multicast and broadcast, corresponding Ethernet addresses
00822  * are selected and the packet is transmitted on the link.
00823  *
00824  * For unicast addresses, the packet is submitted to etharp_query(). In
00825  * case the IP address is outside the local network, the IP address of
00826  * the gateway is used.
00827  *
00828  * @param netif The lwIP network interface which the IP packet will be sent on.
00829  * @param q The pbuf(s) containing the IP packet to be sent.
00830  * @param ipaddr The IP address of the packet destination.
00831  *
00832  * @return
00833  * - ERR_RTE No route to destination (no gateway to external networks),
00834  * or the return type of either etharp_query() or etharp_send_ip().
00835  */
00836 err_t
00837 etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
00838 {
00839   struct eth_addr *dest, mcastaddr;
00840 
00841   /* make room for Ethernet header - should not fail */
00842   if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
00843     /* bail out */
00844     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
00845       ("etharp_output: could not allocate room for header.\n"));
00846     LINK_STATS_INC(link.lenerr);
00847     return ERR_BUF;
00848   }
00849 
00850   /* assume unresolved Ethernet address */
00851   dest = NULL;
00852   /* Determine on destination hardware address. Broadcasts and multicasts
00853    * are special, other IP addresses are looked up in the ARP table. */
00854 
00855   /* broadcast destination IP address? */
00856   if (ip_addr_isbroadcast(ipaddr, netif)) {
00857     /* broadcast on Ethernet also */
00858     dest = (struct eth_addr *)&ethbroadcast;
00859   /* multicast destination IP address? */
00860   } else if (ip_addr_ismulticast(ipaddr)) {
00861     /* Hash IP multicast address to MAC address.*/
00862     mcastaddr.addr[0] = 0x01;
00863     mcastaddr.addr[1] = 0x00;
00864     mcastaddr.addr[2] = 0x5e;
00865     mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
00866     mcastaddr.addr[4] = ip4_addr3(ipaddr);
00867     mcastaddr.addr[5] = ip4_addr4(ipaddr);
00868     /* destination Ethernet address is multicast */
00869     dest = &mcastaddr;
00870   /* unicast destination IP address? */
00871   } else {
00872     /* outside local network? */
00873     if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask)) &&
00874         !ip_addr_islinklocal(ipaddr)) {
00875 #if LWIP_AUTOIP
00876       struct ip_hdr *iphdr = (struct ip_hdr*)((u8_t*)q->payload +
00877         sizeof(struct eth_hdr));
00878       /* According to RFC 3297, chapter 2.6.2 (Forwarding Rules), a packet with
00879          a link-local source address must always be "directly to its destination
00880          on the same physical link. The host MUST NOT send the packet to any
00881          router for forwarding". */
00882       if (!ip_addr_islinklocal(&iphdr->src))
00883 #endif /* LWIP_AUTOIP */
00884       {
00885         /* interface has default gateway? */
00886         if (!ip_addr_isany(&netif->gw)) {
00887           /* send to hardware address of default gateway IP address */
00888           ipaddr = &(netif->gw);
00889         /* no default gateway available */
00890         } else {
00891           /* no route to destination error (default gateway missing) */
00892           return ERR_RTE;
00893         }
00894       }
00895     }
00896 #if LWIP_NETIF_HWADDRHINT
00897     if (netif->addr_hint != NULL) {
00898       /* per-pcb cached entry was given */
00899       u8_t etharp_cached_entry = *(netif->addr_hint);
00900       if (etharp_cached_entry < ARP_TABLE_SIZE) {
00901 #endif /* LWIP_NETIF_HWADDRHINT */
00902         if ((arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) &&
00903             (ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr))) {
00904           /* the per-pcb-cached entry is stable and the right one! */
00905           ETHARP_STATS_INC(etharp.cachehit);
00906           return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr),
00907             &arp_table[etharp_cached_entry].ethaddr);
00908         }
00909 #if LWIP_NETIF_HWADDRHINT
00910       }
00911     }
00912 #endif /* LWIP_NETIF_HWADDRHINT */
00913     /* queue on destination Ethernet address belonging to ipaddr */
00914     return etharp_query(netif, ipaddr, q);
00915   }
00916 
00917   /* continuation for multicast/broadcast destinations */
00918   /* obtain source Ethernet address of the given interface */
00919   /* send packet directly on the link */
00920   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
00921 }
00922 
00923 /**
00924  * Send an ARP request for the given IP address and/or queue a packet.
00925  *
00926  * If the IP address was not yet in the cache, a pending ARP cache entry
00927  * is added and an ARP request is sent for the given address. The packet
00928  * is queued on this entry.
00929  *
00930  * If the IP address was already pending in the cache, a new ARP request
00931  * is sent for the given address. The packet is queued on this entry.
00932  *
00933  * If the IP address was already stable in the cache, and a packet is
00934  * given, it is directly sent and no ARP request is sent out. 
00935  * 
00936  * If the IP address was already stable in the cache, and no packet is
00937  * given, an ARP request is sent out.
00938  * 
00939  * @param netif The lwIP network interface on which ipaddr
00940  * must be queried for.
00941  * @param ipaddr The IP address to be resolved.
00942  * @param q If non-NULL, a pbuf that must be delivered to the IP address.
00943  * q is not freed by this function.
00944  *
00945  * @note q must only be ONE packet, not a packet queue!
00946  *
00947  * @return
00948  * - ERR_BUF Could not make room for Ethernet header.
00949  * - ERR_MEM Hardware address unknown, and no more ARP entries available
00950  *   to query for address or queue the packet.
00951  * - ERR_MEM Could not queue packet due to memory shortage.
00952  * - ERR_RTE No route to destination (no gateway to external networks).
00953  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00954  *
00955  */
00956 err_t
00957 etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
00958 {
00959   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
00960   err_t result = ERR_MEM;
00961   s8_t i; /* ARP entry index */
00962 
00963   /* non-unicast address? */
00964   if (ip_addr_isbroadcast(ipaddr, netif) ||
00965       ip_addr_ismulticast(ipaddr) ||
00966       ip_addr_isany(ipaddr)) {
00967     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
00968     return ERR_ARG;
00969   }
00970 
00971   /* find entry in ARP cache, ask to create entry if queueing packet */
00972   i = find_entry(ipaddr, ETHARP_FLAG_TRY_HARD);
00973 
00974   /* could not find or create entry? */
00975   if (i < 0) {
00976     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
00977     if (q) {
00978       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
00979       ETHARP_STATS_INC(etharp.memerr);
00980     }
00981     return (err_t)i;
00982   }
00983 
00984   /* mark a fresh entry as pending (we just sent a request) */
00985   if (arp_table[i].state == ETHARP_STATE_EMPTY) {
00986     arp_table[i].state = ETHARP_STATE_PENDING;
00987   }
00988 
00989   /* { i is either a STABLE or (new or existing) PENDING entry } */
00990   LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
00991   ((arp_table[i].state == ETHARP_STATE_PENDING) ||
00992    (arp_table[i].state == ETHARP_STATE_STABLE)));
00993 
00994   /* do we have a pending entry? or an implicit query request? */
00995   if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
00996     /* try to resolve it; send out ARP request */
00997     result = etharp_request(netif, ipaddr);
00998     if (result != ERR_OK) {
00999       /* ARP request couldn't be sent */
01000       /* We don't re-send arp request in etharp_tmr, but we still queue packets,
01001          since this failure could be temporary, and the next packet calling
01002          etharp_query again could lead to sending the queued packets. */
01003     }
01004     if (q == NULL) {
01005       return result;
01006     }
01007   }
01008 
01009   /* packet given? */
01010   LWIP_ASSERT("q != NULL", q != NULL);
01011   /* stable entry? */
01012   if (arp_table[i].state == ETHARP_STATE_STABLE) {
01013     /* we have a valid IP->Ethernet address mapping */
01014     ETHARP_SET_HINT(netif, i);
01015     /* send the packet */
01016     result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
01017   /* pending entry? (either just created or already pending */
01018   } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
01019     /* entry is still pending, queue the given packet 'q' */
01020     struct pbuf *p;
01021     int copy_needed = 0;
01022     /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
01023      * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
01024      * PBUF_ROMs can be left as they are, since ROM must not get changed. */
01025     p = q;
01026     while (p) {
01027       LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
01028       if(p->type != PBUF_ROM) {
01029         copy_needed = 1;
01030         break;
01031       }
01032       p = p->next;
01033     }
01034     if(copy_needed) {
01035       /* copy the whole packet into new pbufs */
01036       p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
01037       if(p != NULL) {
01038         if (pbuf_copy(p, q) != ERR_OK) {
01039           pbuf_free(p);
01040           p = NULL;
01041         }
01042       }
01043     } else {
01044       /* referencing the old pbuf is enough */
01045       p = q;
01046       pbuf_ref(p);
01047     }
01048     /* packet could be taken over? */
01049     if (p != NULL) {
01050       /* queue packet ... */
01051 #if ARP_QUEUEING
01052       struct etharp_q_entry *new_entry;
01053       /* allocate a new arp queue entry */
01054       new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
01055       if (new_entry != NULL) {
01056         new_entry->next = 0;
01057         new_entry->p = p;
01058         if(arp_table[i].q != NULL) {
01059           /* queue was already existent, append the new entry to the end */
01060           struct etharp_q_entry *r;
01061           r = arp_table[i].q;
01062           while (r->next != NULL) {
01063             r = r->next;
01064           }
01065           r->next = new_entry;
01066         } else {
01067           /* queue did not exist, first item in queue */
01068           arp_table[i].q = new_entry;
01069         }
01070         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01071         result = ERR_OK;
01072       } else {
01073         /* the pool MEMP_ARP_QUEUE is empty */
01074         pbuf_free(p);
01075         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));
01076         result = ERR_MEM;
01077       }
01078 #else /* ARP_QUEUEING */
01079       /* always queue one packet per ARP request only, freeing a previously queued packet */
01080       if (arp_table[i].q != NULL) {
01081         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: dropped previously queued packet %p for ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01082         pbuf_free(arp_table[i].q);
01083       }
01084       arp_table[i].q = p;
01085       result = ERR_OK;
01086       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01087 #endif /* ARP_QUEUEING */
01088     } else {
01089       ETHARP_STATS_INC(etharp.memerr);
01090       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));
01091       result = ERR_MEM;
01092     }
01093   }
01094   return result;
01095 }
01096 
01097 /**
01098  * Send a raw ARP packet (opcode and all addresses can be modified)
01099  *
01100  * @param netif the lwip network interface on which to send the ARP packet
01101  * @param ethsrc_addr the source MAC address for the ethernet header
01102  * @param ethdst_addr the destination MAC address for the ethernet header
01103  * @param hwsrc_addr the source MAC address for the ARP protocol header
01104  * @param ipsrc_addr the source IP address for the ARP protocol header
01105  * @param hwdst_addr the destination MAC address for the ARP protocol header
01106  * @param ipdst_addr the destination IP address for the ARP protocol header
01107  * @param opcode the type of the ARP packet
01108  * @return ERR_OK if the ARP packet has been sent
01109  *         ERR_MEM if the ARP packet couldn't be allocated
01110  *         any other err_t on failure
01111  */
01112 #if !LWIP_AUTOIP
01113 static
01114 #endif /* LWIP_AUTOIP */
01115 err_t
01116 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
01117            const struct eth_addr *ethdst_addr,
01118            const struct eth_addr *hwsrc_addr, const ip_addr_t *ipsrc_addr,
01119            const struct eth_addr *hwdst_addr, const ip_addr_t *ipdst_addr,
01120            const u16_t opcode)
01121 {
01122   struct pbuf *p;
01123   err_t result = ERR_OK;
01124   struct eth_hdr *ethhdr;
01125   struct etharp_hdr *hdr;
01126 #if LWIP_AUTOIP
01127   const u8_t * ethdst_hwaddr;
01128 #endif /* LWIP_AUTOIP */
01129 
01130   /* allocate a pbuf for the outgoing ARP request packet */
01131   p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
01132   /* could allocate a pbuf for an ARP request? */
01133   if (p == NULL) {
01134     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
01135       ("etharp_raw: could not allocate pbuf for ARP request.\n"));
01136     ETHARP_STATS_INC(etharp.memerr);
01137     return ERR_MEM;
01138   }
01139   LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
01140               (p->len >= SIZEOF_ETHARP_PACKET));
01141 
01142   ethhdr = (struct eth_hdr *)p->payload;
01143   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
01144   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
01145   hdr->opcode = htons(opcode);
01146 
01147   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
01148               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
01149 #if LWIP_AUTOIP
01150   /* If we are using Link-Local, all ARP packets that contain a Link-Local
01151    * 'sender IP address' MUST be sent using link-layer broadcast instead of
01152    * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
01153   ethdst_hwaddr = ip_addr_islinklocal(ipsrc_addr) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
01154 #endif /* LWIP_AUTOIP */
01155   /* Write the ARP MAC-Addresses */
01156   ETHADDR16_COPY(&hdr->shwaddr, hwsrc_addr);
01157   ETHADDR16_COPY(&hdr->dhwaddr, hwdst_addr);
01158   /* Write the Ethernet MAC-Addresses */
01159 #if LWIP_AUTOIP
01160   ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
01161 #else  /* LWIP_AUTOIP */
01162   ETHADDR16_COPY(&ethhdr->dest, ethdst_addr);
01163 #endif /* LWIP_AUTOIP */
01164   ETHADDR16_COPY(&ethhdr->src, ethsrc_addr);
01165   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
01166    * structure packing. */ 
01167   IPADDR2_COPY(&hdr->sipaddr, ipsrc_addr);
01168   IPADDR2_COPY(&hdr->dipaddr, ipdst_addr);
01169 
01170   hdr->hwtype = PP_HTONS(HWTYPE_ETHERNET);
01171   hdr->proto = PP_HTONS(ETHTYPE_IP);
01172   /* set hwlen and protolen */
01173   hdr->hwlen = ETHARP_HWADDR_LEN;
01174   hdr->protolen = sizeof(ip_addr_t);
01175 
01176   ethhdr->type = PP_HTONS(ETHTYPE_ARP);
01177   /* send ARP query */
01178   result = netif->linkoutput(netif, p);
01179   ETHARP_STATS_INC(etharp.xmit);
01180   /* free ARP query packet */
01181   pbuf_free(p);
01182   p = NULL;
01183   /* could not allocate pbuf for ARP request */
01184 
01185   return result;
01186 }
01187 
01188 /**
01189  * Send an ARP request packet asking for ipaddr.
01190  *
01191  * @param netif the lwip network interface on which to send the request
01192  * @param ipaddr the IP address for which to ask
01193  * @return ERR_OK if the request has been sent
01194  *         ERR_MEM if the ARP packet couldn't be allocated
01195  *         any other err_t on failure
01196  */
01197 err_t
01198 etharp_request(struct netif *netif, ip_addr_t *ipaddr)
01199 {
01200   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
01201   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
01202                     (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
01203                     ipaddr, ARP_REQUEST);
01204 }
01205 #endif /* LWIP_ARP */
01206 
01207 /**
01208  * Process received ethernet frames. Using this function instead of directly
01209  * calling ip_input and passing ARP frames through etharp in ethernetif_input,
01210  * the ARP cache is protected from concurrent access.
01211  *
01212  * @param p the recevied packet, p->payload pointing to the ethernet header
01213  * @param netif the network interface on which the packet was received
01214  */
01215 err_t
01216 ethernet_input(struct pbuf *p, struct netif *netif)
01217 {
01218   struct eth_hdr* ethhdr;
01219   u16_t type;
01220   s16_t ip_hdr_offset = SIZEOF_ETH_HDR;
01221 
01222   if (p->len <= SIZEOF_ETH_HDR) {
01223     /* a packet with only an ethernet header (or less) is not valid for us */
01224     ETHARP_STATS_INC(etharp.proterr);
01225     ETHARP_STATS_INC(etharp.drop);
01226     goto free_and_return;
01227   }
01228 
01229   /* points to packet payload, which starts with an Ethernet header */
01230   ethhdr = (struct eth_hdr *)p->payload;
01231   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
01232     ("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",
01233      (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
01234      (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
01235      (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
01236      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
01237      (unsigned)htons(ethhdr->type)));
01238 
01239   type = ethhdr->type;
01240 #if ETHARP_SUPPORT_VLAN
01241   if (type == PP_HTONS(ETHTYPE_VLAN)) {
01242     struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
01243     if (p->len <= SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR) {
01244       /* a packet with only an ethernet/vlan header (or less) is not valid for us */
01245       ETHARP_STATS_INC(etharp.proterr);
01246       ETHARP_STATS_INC(etharp.drop);
01247       goto free_and_return;
01248     }
01249 #ifdef ETHARP_VLAN_CHECK /* if not, allow all VLANs */
01250     if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
01251       /* silently ignore this packet: not for our VLAN */
01252       pbuf_free(p);
01253       return ERR_OK;
01254     }
01255 #endif /* ETHARP_VLAN_CHECK */
01256     type = vlan->tpid;
01257     ip_hdr_offset = SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR;
01258   }
01259 #endif /* ETHARP_SUPPORT_VLAN */
01260 
01261 #if LWIP_ARP_FILTER_NETIF
01262   netif = LWIP_ARP_FILTER_NETIF_FN(p, netif, htons(type));
01263 #endif /* LWIP_ARP_FILTER_NETIF*/
01264 
01265   switch (type) {
01266 #if LWIP_ARP
01267     /* IP packet? */
01268     case PP_HTONS(ETHTYPE_IP):
01269       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01270         goto free_and_return;
01271       }
01272 #if ETHARP_TRUST_IP_MAC
01273       /* update ARP table */
01274       etharp_ip_input(netif, p);
01275 #endif /* ETHARP_TRUST_IP_MAC */
01276       /* skip Ethernet header */
01277       if(pbuf_header(p, -ip_hdr_offset)) {
01278         LWIP_ASSERT("Can't move over header in packet", 0);
01279         goto free_and_return;
01280       } else {
01281         /* pass to IP layer */
01282         ip_input(p, netif);
01283       }
01284       break;
01285       
01286     case PP_HTONS(ETHTYPE_ARP):
01287       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01288         goto free_and_return;
01289       }
01290       /* pass p to ARP module */
01291       etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
01292       break;
01293 #endif /* LWIP_ARP */
01294 #if PPPOE_SUPPORT
01295     case PP_HTONS(ETHTYPE_PPPOEDISC): /* PPP Over Ethernet Discovery Stage */
01296       pppoe_disc_input(netif, p);
01297       break;
01298 
01299     case PP_HTONS(ETHTYPE_PPPOE): /* PPP Over Ethernet Session Stage */
01300       pppoe_data_input(netif, p);
01301       break;
01302 #endif /* PPPOE_SUPPORT */
01303 
01304     default:
01305       ETHARP_STATS_INC(etharp.proterr);
01306       ETHARP_STATS_INC(etharp.drop);
01307       goto free_and_return;
01308   }
01309 
01310   /* This means the pbuf is freed or consumed,
01311      so the caller doesn't have to free it again */
01312   return ERR_OK;
01313 
01314 free_and_return:
01315   pbuf_free(p);
01316   return ERR_OK;
01317 }
01318 #endif /* LWIP_ARP || LWIP_ETHERNET */