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 /** The 24-bit IANA multicast OUI is 01-00-5e: */
00069 #define LL_MULTICAST_ADDR_0 0x01
00070 #define LL_MULTICAST_ADDR_1 0x00
00071 #define LL_MULTICAST_ADDR_2 0x5e
00072 
00073 #if LWIP_ARP /* don't build if not configured for use in lwipopts.h */
00074 
00075 /** the time an ARP entry stays valid after its last update,
00076  *  for ARP_TMR_INTERVAL = 5000, this is
00077  *  (240 * 5) seconds = 20 minutes.
00078  */
00079 #define ARP_MAXAGE              240
00080 /** Re-request a used ARP entry 1 minute before it would expire to prevent
00081  *  breaking a steadily used connection because the ARP entry timed out. */
00082 #define ARP_AGE_REREQUEST_USED  (ARP_MAXAGE - 12)
00083 
00084 /** the time an ARP entry stays pending after first request,
00085  *  for ARP_TMR_INTERVAL = 5000, this is
00086  *  (2 * 5) seconds = 10 seconds.
00087  * 
00088  *  @internal Keep this number at least 2, otherwise it might
00089  *  run out instantly if the timeout occurs directly after a request.
00090  */
00091 #define ARP_MAXPENDING 2
00092 
00093 #define HWTYPE_ETHERNET 1
00094 
00095 enum etharp_state {
00096   ETHARP_STATE_EMPTY = 0,
00097   ETHARP_STATE_PENDING,
00098   ETHARP_STATE_STABLE,
00099   ETHARP_STATE_STABLE_REREQUESTING
00100 #if ETHARP_SUPPORT_STATIC_ENTRIES
00101   ,ETHARP_STATE_STATIC
00102 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00103 };
00104 
00105 struct etharp_entry {
00106 #if ARP_QUEUEING
00107   /** Pointer to queue of pending outgoing packets on this ARP entry. */
00108   struct etharp_q_entry *q;
00109 #else /* ARP_QUEUEING */
00110   /** Pointer to a single pending outgoing packet on this ARP entry. */
00111   struct pbuf *q;
00112 #endif /* ARP_QUEUEING */
00113   ip_addr_t ipaddr;
00114   struct netif *netif;
00115   struct eth_addr ethaddr;
00116   u8_t state;
00117   u8_t ctime;
00118 };
00119 
00120 static struct etharp_entry arp_table[ARP_TABLE_SIZE];
00121 
00122 #if !LWIP_NETIF_HWADDRHINT
00123 static u8_t etharp_cached_entry;
00124 #endif /* !LWIP_NETIF_HWADDRHINT */
00125 
00126 /** Try hard to create a new entry - we want the IP address to appear in
00127     the cache (even if this means removing an active entry or so). */
00128 #define ETHARP_FLAG_TRY_HARD     1
00129 #define ETHARP_FLAG_FIND_ONLY    2
00130 #if ETHARP_SUPPORT_STATIC_ENTRIES
00131 #define ETHARP_FLAG_STATIC_ENTRY 4
00132 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00133 
00134 #if LWIP_NETIF_HWADDRHINT
00135 #define ETHARP_SET_HINT(netif, hint)  if (((netif) != NULL) && ((netif)->addr_hint != NULL))  \
00136                                       *((netif)->addr_hint) = (hint);
00137 #else /* LWIP_NETIF_HWADDRHINT */
00138 #define ETHARP_SET_HINT(netif, hint)  (etharp_cached_entry = (hint))
00139 #endif /* LWIP_NETIF_HWADDRHINT */
00140 
00141 
00142 /* Some checks, instead of etharp_init(): */
00143 #if (LWIP_ARP && (ARP_TABLE_SIZE > 0x7f))
00144   #error "ARP_TABLE_SIZE must fit in an s8_t, you have to reduce it in your lwipopts.h"
00145 #endif
00146 
00147 
00148 #if ARP_QUEUEING
00149 /**
00150  * Free a complete queue of etharp entries
00151  *
00152  * @param q a qeueue of etharp_q_entry's to free
00153  */
00154 static void
00155 free_etharp_q(struct etharp_q_entry *q)
00156 {
00157   struct etharp_q_entry *r;
00158   LWIP_ASSERT("q != NULL", q != NULL);
00159   LWIP_ASSERT("q->p != NULL", q->p != NULL);
00160   while (q) {
00161     r = q;
00162     q = q->next;
00163     LWIP_ASSERT("r->p != NULL", (r->p != NULL));
00164     pbuf_free(r->p);
00165     memp_free(MEMP_ARP_QUEUE, r);
00166   }
00167 }
00168 #else /* ARP_QUEUEING */
00169 
00170 /** Compatibility define: free the queued pbuf */
00171 #define free_etharp_q(q) pbuf_free(q)
00172 
00173 #endif /* ARP_QUEUEING */
00174 
00175 /** Clean up ARP table entries */
00176 static void
00177 etharp_free_entry(int i)
00178 {
00179   /* remove from SNMP ARP index tree */
00180   snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00181   /* and empty packet queue */
00182   if (arp_table[i].q != NULL) {
00183     /* remove all queued packets */
00184     LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_free_entry: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
00185     free_etharp_q(arp_table[i].q);
00186     arp_table[i].q = NULL;
00187   }
00188   /* recycle entry for re-use */
00189   arp_table[i].state = ETHARP_STATE_EMPTY;
00190 #ifdef LWIP_DEBUG
00191   /* for debugging, clean out the complete entry */
00192   arp_table[i].ctime = 0;
00193   arp_table[i].netif = NULL;
00194   ip_addr_set_zero(&arp_table[i].ipaddr);
00195   arp_table[i].ethaddr = ethzero;
00196 #endif /* LWIP_DEBUG */
00197 }
00198 
00199 /**
00200  * Clears expired entries in the ARP table.
00201  *
00202  * This function should be called every ETHARP_TMR_INTERVAL milliseconds (5 seconds),
00203  * in order to expire entries in the ARP table.
00204  */
00205 void
00206 etharp_tmr(void)
00207 {
00208   u8_t i;
00209 
00210   LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
00211   /* remove expired entries from the ARP table */
00212   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00213     u8_t state = arp_table[i].state;
00214     if (state != ETHARP_STATE_EMPTY
00215 #if ETHARP_SUPPORT_STATIC_ENTRIES
00216       && (state != ETHARP_STATE_STATIC)
00217 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00218       ) {
00219       arp_table[i].ctime++;
00220       if ((arp_table[i].ctime >= ARP_MAXAGE) ||
00221           ((arp_table[i].state == ETHARP_STATE_PENDING)  &&
00222            (arp_table[i].ctime >= ARP_MAXPENDING))) {
00223         /* pending or stable entry has become old! */
00224         LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
00225              arp_table[i].state >= ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
00226         /* clean up entries that have just been expired */
00227         etharp_free_entry(i);
00228       }
00229       else if (arp_table[i].state == ETHARP_STATE_STABLE_REREQUESTING) {
00230         /* Reset state to stable, so that the next transmitted packet will
00231            re-send an ARP request. */
00232         arp_table[i].state = ETHARP_STATE_STABLE;
00233       }
00234 #if ARP_QUEUEING
00235       /* still pending entry? (not expired) */
00236       if (arp_table[i].state == ETHARP_STATE_PENDING) {
00237         /* resend an ARP query here? */
00238       }
00239 #endif /* ARP_QUEUEING */
00240     }
00241   }
00242 }
00243 
00244 /**
00245  * Search the ARP table for a matching or new entry.
00246  * 
00247  * If an IP address is given, return a pending or stable ARP entry that matches
00248  * the address. If no match is found, create a new entry with this address set,
00249  * but in state ETHARP_EMPTY. The caller must check and possibly change the
00250  * state of the returned entry.
00251  * 
00252  * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
00253  * 
00254  * In all cases, attempt to create new entries from an empty entry. If no
00255  * empty entries are available and ETHARP_FLAG_TRY_HARD flag is set, recycle
00256  * old entries. Heuristic choose the least important entry for recycling.
00257  *
00258  * @param ipaddr IP address to find in ARP cache, or to add if not found.
00259  * @param flags @see definition of ETHARP_FLAG_*
00260  * @param netif netif related to this address (used for NETIF_HWADDRHINT)
00261  *  
00262  * @return The ARP entry index that matched or is created, ERR_MEM if no
00263  * entry is found or could be recycled.
00264  */
00265 static s8_t
00266 etharp_find_entry(ip_addr_t *ipaddr, u8_t flags)
00267 {
00268   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
00269   s8_t empty = ARP_TABLE_SIZE;
00270   u8_t i = 0, age_pending = 0, age_stable = 0;
00271   /* oldest entry with packets on queue */
00272   s8_t old_queue = ARP_TABLE_SIZE;
00273   /* its age */
00274   u8_t age_queue = 0;
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     u8_t state = arp_table[i].state;
00293     /* no empty entry found yet and now we do find one? */
00294     if ((empty == ARP_TABLE_SIZE) && (state == ETHARP_STATE_EMPTY)) {
00295       LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_find_entry: found empty entry %"U16_F"\n", (u16_t)i));
00296       /* remember first empty entry */
00297       empty = i;
00298     } else if (state != ETHARP_STATE_EMPTY) {
00299       LWIP_ASSERT("state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE",
00300         state == ETHARP_STATE_PENDING || state >= ETHARP_STATE_STABLE);
00301       /* if given, does IP address match IP address in ARP entry? */
00302       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00303         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: found matching entry %"U16_F"\n", (u16_t)i));
00304         /* found exact IP address match, simply bail out */
00305         return i;
00306       }
00307       /* pending entry? */
00308       if (state == ETHARP_STATE_PENDING) {
00309         /* pending with queued packets? */
00310         if (arp_table[i].q != NULL) {
00311           if (arp_table[i].ctime >= age_queue) {
00312             old_queue = i;
00313             age_queue = arp_table[i].ctime;
00314           }
00315         } else
00316         /* pending without queued packets? */
00317         {
00318           if (arp_table[i].ctime >= age_pending) {
00319             old_pending = i;
00320             age_pending = arp_table[i].ctime;
00321           }
00322         }
00323       /* stable entry? */
00324       } else if (state >= ETHARP_STATE_STABLE) {
00325 #if ETHARP_SUPPORT_STATIC_ENTRIES
00326         /* don't record old_stable for static entries since they never expire */
00327         if (state < ETHARP_STATE_STATIC)
00328 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00329         {
00330           /* remember entry with oldest stable entry in oldest, its age in maxtime */
00331           if (arp_table[i].ctime >= age_stable) {
00332             old_stable = i;
00333             age_stable = arp_table[i].ctime;
00334           }
00335         }
00336       }
00337     }
00338   }
00339   /* { we have no match } => try to create a new entry */
00340    
00341   /* don't create new entry, only search? */
00342   if (((flags & ETHARP_FLAG_FIND_ONLY) != 0) ||
00343       /* or no empty entry found and not allowed to recycle? */
00344       ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_FLAG_TRY_HARD) == 0))) {
00345     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty entry found and not allowed to recycle\n"));
00346     return (s8_t)ERR_MEM;
00347   }
00348   
00349   /* b) choose the least destructive entry to recycle:
00350    * 1) empty entry
00351    * 2) oldest stable entry
00352    * 3) oldest pending entry without queued packets
00353    * 4) oldest pending entry with queued packets
00354    * 
00355    * { ETHARP_FLAG_TRY_HARD is set at this point }
00356    */ 
00357 
00358   /* 1) empty entry available? */
00359   if (empty < ARP_TABLE_SIZE) {
00360     i = empty;
00361     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
00362   } else {
00363     /* 2) found recyclable stable entry? */
00364     if (old_stable < ARP_TABLE_SIZE) {
00365       /* recycle oldest stable*/
00366       i = old_stable;
00367       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
00368       /* no queued packets should exist on stable entries */
00369       LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
00370     /* 3) found recyclable pending entry without queued packets? */
00371     } else if (old_pending < ARP_TABLE_SIZE) {
00372       /* recycle oldest pending */
00373       i = old_pending;
00374       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
00375     /* 4) found recyclable pending entry with queued packets? */
00376     } else if (old_queue < ARP_TABLE_SIZE) {
00377       /* recycle oldest pending (queued packets are free in etharp_free_entry) */
00378       i = old_queue;
00379       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].q)));
00380       /* no empty or recyclable entries found */
00381     } else {
00382       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_find_entry: no empty or recyclable entries found\n"));
00383       return (s8_t)ERR_MEM;
00384     }
00385 
00386     /* { empty or recyclable entry found } */
00387     LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00388     etharp_free_entry(i);
00389   }
00390 
00391   LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00392   LWIP_ASSERT("arp_table[i].state == ETHARP_STATE_EMPTY",
00393     arp_table[i].state == ETHARP_STATE_EMPTY);
00394 
00395   /* IP address given? */
00396   if (ipaddr != NULL) {
00397     /* set IP address */
00398     ip_addr_copy(arp_table[i].ipaddr, *ipaddr);
00399   }
00400   arp_table[i].ctime = 0;
00401   return (err_t)i;
00402 }
00403 
00404 /**
00405  * Send an IP packet on the network using netif->linkoutput
00406  * The ethernet header is filled in before sending.
00407  *
00408  * @params netif the lwIP network interface on which to send the packet
00409  * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
00410  * @params src the source MAC address to be copied into the ethernet header
00411  * @params dst the destination MAC address to be copied into the ethernet header
00412  * @return ERR_OK if the packet was sent, any other err_t on failure
00413  */
00414 static err_t
00415 etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
00416 {
00417   struct eth_hdr *ethhdr = (struct eth_hdr *)p->payload;
00418 
00419   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00420               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00421   ETHADDR32_COPY(&ethhdr->dest, dst);
00422   ETHADDR16_COPY(&ethhdr->src, src);
00423   ethhdr->type = PP_HTONS(ETHTYPE_IP);
00424   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
00425   /* send the packet */
00426   return netif->linkoutput(netif, p);
00427 }
00428 
00429 /**
00430  * Update (or insert) a IP/MAC address pair in the ARP cache.
00431  *
00432  * If a pending entry is resolved, any queued packets will be sent
00433  * at this point.
00434  * 
00435  * @param netif netif related to this entry (used for NETIF_ADDRHINT)
00436  * @param ipaddr IP address of the inserted ARP entry.
00437  * @param ethaddr Ethernet address of the inserted ARP entry.
00438  * @param flags @see definition of ETHARP_FLAG_*
00439  *
00440  * @return
00441  * - ERR_OK Succesfully updated ARP cache.
00442  * - ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set.
00443  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00444  *
00445  * @see pbuf_free()
00446  */
00447 static err_t
00448 etharp_update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
00449 {
00450   s8_t i;
00451   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
00452   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_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",
00453     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00454     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00455     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00456   /* non-unicast address? */
00457   if (ip_addr_isany(ipaddr) ||
00458       ip_addr_isbroadcast(ipaddr, netif) ||
00459       ip_addr_ismulticast(ipaddr)) {
00460     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
00461     return ERR_ARG;
00462   }
00463   /* find or create ARP entry */
00464   i = etharp_find_entry(ipaddr, flags);
00465   /* bail out if no entry could be found */
00466   if (i < 0) {
00467     return (err_t)i;
00468   }
00469 
00470 #if ETHARP_SUPPORT_STATIC_ENTRIES
00471   if (flags & ETHARP_FLAG_STATIC_ENTRY) {
00472     /* record static type */
00473     arp_table[i].state = ETHARP_STATE_STATIC;
00474   } else
00475 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00476   {
00477     /* mark it stable */
00478     arp_table[i].state = ETHARP_STATE_STABLE;
00479   }
00480 
00481   /* record network interface */
00482   arp_table[i].netif = netif;
00483   /* insert in SNMP ARP index tree */
00484   snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
00485 
00486   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
00487   /* update address */
00488   ETHADDR32_COPY(&arp_table[i].ethaddr, ethaddr);
00489   /* reset time stamp */
00490   arp_table[i].ctime = 0;
00491   /* this is where we will send out queued packets! */
00492 #if ARP_QUEUEING
00493   while (arp_table[i].q != NULL) {
00494     struct pbuf *p;
00495     /* remember remainder of queue */
00496     struct etharp_q_entry *q = arp_table[i].q;
00497     /* pop first item off the queue */
00498     arp_table[i].q = q->next;
00499     /* get the packet pointer */
00500     p = q->p;
00501     /* now queue entry can be freed */
00502     memp_free(MEMP_ARP_QUEUE, q);
00503 #else /* ARP_QUEUEING */
00504   if (arp_table[i].q != NULL) {
00505     struct pbuf *p = arp_table[i].q;
00506     arp_table[i].q = NULL;
00507 #endif /* ARP_QUEUEING */
00508     /* send the queued IP packet */
00509     etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
00510     /* free the queued IP packet */
00511     pbuf_free(p);
00512   }
00513   return ERR_OK;
00514 }
00515 
00516 #if ETHARP_SUPPORT_STATIC_ENTRIES
00517 /** Add a new static entry to the ARP table. If an entry exists for the
00518  * specified IP address, this entry is overwritten.
00519  * If packets are queued for the specified IP address, they are sent out.
00520  *
00521  * @param ipaddr IP address for the new static entry
00522  * @param ethaddr ethernet address for the new static entry
00523  * @return @see return values of etharp_add_static_entry
00524  */
00525 err_t
00526 etharp_add_static_entry(ip_addr_t *ipaddr, struct eth_addr *ethaddr)
00527 {
00528   struct netif *netif;
00529   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",
00530     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00531     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00532     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00533 
00534   netif = ip_route(ipaddr);
00535   if (netif == NULL) {
00536     return ERR_RTE;
00537   }
00538 
00539   return etharp_update_arp_entry(netif, ipaddr, ethaddr, ETHARP_FLAG_TRY_HARD | ETHARP_FLAG_STATIC_ENTRY);
00540 }
00541 
00542 /** Remove a static entry from the ARP table previously added with a call to
00543  * etharp_add_static_entry.
00544  *
00545  * @param ipaddr IP address of the static entry to remove
00546  * @return ERR_OK: entry removed
00547  *         ERR_MEM: entry wasn't found
00548  *         ERR_ARG: entry wasn't a static entry but a dynamic one
00549  */
00550 err_t
00551 etharp_remove_static_entry(ip_addr_t *ipaddr)
00552 {
00553   s8_t i;
00554   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00555     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
00556 
00557   /* find or create ARP entry */
00558   i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
00559   /* bail out if no entry could be found */
00560   if (i < 0) {
00561     return (err_t)i;
00562   }
00563 
00564   if (arp_table[i].state != ETHARP_STATE_STATIC) {
00565     /* entry wasn't a static entry, cannot remove it */
00566     return ERR_ARG;
00567   }
00568   /* entry found, free it */
00569   etharp_free_entry(i);
00570   return ERR_OK;
00571 }
00572 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00573 
00574 /**
00575  * Remove all ARP table entries of the specified netif.
00576  *
00577  * @param netif points to a network interface
00578  */
00579 void etharp_cleanup_netif(struct netif *netif)
00580 {
00581   u8_t i;
00582 
00583   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00584     u8_t state = arp_table[i].state;
00585     if ((state != ETHARP_STATE_EMPTY) && (arp_table[i].netif == netif)) {
00586       etharp_free_entry(i);
00587     }
00588   }
00589 }
00590 
00591 /**
00592  * Finds (stable) ethernet/IP address pair from ARP table
00593  * using interface and IP address index.
00594  * @note the addresses in the ARP table are in network order!
00595  *
00596  * @param netif points to interface index
00597  * @param ipaddr points to the (network order) IP address index
00598  * @param eth_ret points to return pointer
00599  * @param ip_ret points to return pointer
00600  * @return table index if found, -1 otherwise
00601  */
00602 s8_t
00603 etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
00604          struct eth_addr **eth_ret, ip_addr_t **ip_ret)
00605 {
00606   s8_t i;
00607 
00608   LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL",
00609     eth_ret != NULL && ip_ret != NULL);
00610 
00611   LWIP_UNUSED_ARG(netif);
00612 
00613   i = etharp_find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
00614   if((i >= 0) && (arp_table[i].state >= ETHARP_STATE_STABLE)) {
00615       *eth_ret = &arp_table[i].ethaddr;
00616       *ip_ret = &arp_table[i].ipaddr;
00617       return i;
00618   }
00619   return -1;
00620 }
00621 
00622 #if ETHARP_TRUST_IP_MAC
00623 /**
00624  * Updates the ARP table using the given IP packet.
00625  *
00626  * Uses the incoming IP packet's source address to update the
00627  * ARP cache for the local network. The function does not alter
00628  * or free the packet. This function must be called before the
00629  * packet p is passed to the IP layer.
00630  *
00631  * @param netif The lwIP network interface on which the IP packet pbuf arrived.
00632  * @param p The IP packet that arrived on netif.
00633  *
00634  * @return NULL
00635  *
00636  * @see pbuf_free()
00637  */
00638 static void
00639 etharp_ip_input(struct netif *netif, struct pbuf *p)
00640 {
00641   struct eth_hdr *ethhdr;
00642   struct ip_hdr *iphdr;
00643   ip_addr_t iphdr_src;
00644   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00645 
00646   /* Only insert an entry if the source IP address of the
00647      incoming IP packet comes from a host on the local network. */
00648   ethhdr = (struct eth_hdr *)p->payload;
00649   iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00650 #if ETHARP_SUPPORT_VLAN
00651   if (ethhdr->type == PP_HTONS(ETHTYPE_VLAN)) {
00652     iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00653   }
00654 #endif /* ETHARP_SUPPORT_VLAN */
00655 
00656   ip_addr_copy(iphdr_src, iphdr->src);
00657 
00658   /* source is not on the local network? */
00659   if (!ip_addr_netcmp(&iphdr_src, &(netif->ip_addr), &(netif->netmask))) {
00660     /* do nothing */
00661     return;
00662   }
00663 
00664   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
00665   /* update the source IP address in the cache, if present */
00666   /* @todo We could use ETHARP_FLAG_TRY_HARD if we think we are going to talk
00667    * back soon (for example, if the destination IP address is ours. */
00668   etharp_update_arp_entry(netif, &iphdr_src, &(ethhdr->src), ETHARP_FLAG_FIND_ONLY);
00669 }
00670 #endif /* ETHARP_TRUST_IP_MAC */
00671 
00672 /**
00673  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
00674  * send out queued IP packets. Updates cache with snooped address pairs.
00675  *
00676  * Should be called for incoming ARP packets. The pbuf in the argument
00677  * is freed by this function.
00678  *
00679  * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
00680  * @param ethaddr Ethernet address of netif.
00681  * @param p The ARP packet that arrived on netif. Is freed by this function.
00682  *
00683  * @return NULL
00684  *
00685  * @see pbuf_free()
00686  */
00687 static void
00688 etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
00689 {
00690   struct etharp_hdr *hdr;
00691   struct eth_hdr *ethhdr;
00692   /* these are aligned properly, whereas the ARP header fields might not be */
00693   ip_addr_t sipaddr, dipaddr;
00694   u8_t for_us;
00695 #if LWIP_AUTOIP
00696   const u8_t * ethdst_hwaddr;
00697 #endif /* LWIP_AUTOIP */
00698 
00699   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00700 
00701   /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
00702      since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
00703   if (p->len < SIZEOF_ETHARP_PACKET) {
00704     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00705       ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len,
00706       (s16_t)SIZEOF_ETHARP_PACKET));
00707     ETHARP_STATS_INC(etharp.lenerr);
00708     ETHARP_STATS_INC(etharp.drop);
00709     pbuf_free(p);
00710     return;
00711   }
00712 
00713   ethhdr = (struct eth_hdr *)p->payload;
00714   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00715 #if ETHARP_SUPPORT_VLAN
00716   if (ethhdr->type == PP_HTONS(ETHTYPE_VLAN)) {
00717     hdr = (struct etharp_hdr *)(((u8_t*)ethhdr) + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00718   }
00719 #endif /* ETHARP_SUPPORT_VLAN */
00720 
00721   /* RFC 826 "Packet Reception": */
00722   if ((hdr->hwtype != PP_HTONS(HWTYPE_ETHERNET)) ||
00723       (hdr->hwlen != ETHARP_HWADDR_LEN) ||
00724       (hdr->protolen != sizeof(ip_addr_t)) ||
00725       (hdr->proto != PP_HTONS(ETHTYPE_IP)))  {
00726     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00727       ("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
00728       hdr->hwtype, hdr->hwlen, hdr->proto, hdr->protolen));
00729     ETHARP_STATS_INC(etharp.proterr);
00730     ETHARP_STATS_INC(etharp.drop);
00731     pbuf_free(p);
00732     return;
00733   }
00734   ETHARP_STATS_INC(etharp.recv);
00735 
00736 #if LWIP_AUTOIP
00737   /* We have to check if a host already has configured our random
00738    * created link local address and continously check if there is
00739    * a host with this IP-address so we can detect collisions */
00740   autoip_arp_reply(netif, hdr);
00741 #endif /* LWIP_AUTOIP */
00742 
00743   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00744    * structure packing (not using structure copy which breaks strict-aliasing rules). */
00745   IPADDR2_COPY(&sipaddr, &hdr->sipaddr);
00746   IPADDR2_COPY(&dipaddr, &hdr->dipaddr);
00747 
00748   /* this interface is not configured? */
00749   if (ip_addr_isany(&netif->ip_addr)) {
00750     for_us = 0;
00751   } else {
00752     /* ARP packet directed to us? */
00753     for_us = (u8_t)ip_addr_cmp(&dipaddr, &(netif->ip_addr));
00754   }
00755 
00756   /* ARP message directed to us?
00757       -> add IP address in ARP cache; assume requester wants to talk to us,
00758          can result in directly sending the queued packets for this host.
00759      ARP message not directed to us?
00760       ->  update the source IP address in the cache, if present */
00761   etharp_update_arp_entry(netif, &sipaddr, &(hdr->shwaddr),
00762                    for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY);
00763 
00764   /* now act on the message itself */
00765   switch (hdr->opcode) {
00766   /* ARP request? */
00767   case PP_HTONS(ARP_REQUEST):
00768     /* ARP request. If it asked for our address, we send out a
00769      * reply. In any case, we time-stamp any existing ARP entry,
00770      * and possiby send out an IP packet that was queued on it. */
00771 
00772     LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
00773     /* ARP request for our address? */
00774     if (for_us) {
00775 
00776       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
00777       /* Re-use pbuf to send ARP reply.
00778          Since we are re-using an existing pbuf, we can't call etharp_raw since
00779          that would allocate a new pbuf. */
00780       hdr->opcode = htons(ARP_REPLY);
00781 
00782       IPADDR2_COPY(&hdr->dipaddr, &hdr->sipaddr);
00783       IPADDR2_COPY(&hdr->sipaddr, &netif->ip_addr);
00784 
00785       LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00786                   (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00787 #if LWIP_AUTOIP
00788       /* If we are using Link-Local, all ARP packets that contain a Link-Local
00789        * 'sender IP address' MUST be sent using link-layer broadcast instead of
00790        * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
00791       ethdst_hwaddr = ip_addr_islinklocal(&netif->ip_addr) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
00792 #endif /* LWIP_AUTOIP */
00793 
00794       ETHADDR16_COPY(&hdr->dhwaddr, &hdr->shwaddr);
00795 #if LWIP_AUTOIP
00796       ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
00797 #else  /* LWIP_AUTOIP */
00798       ETHADDR16_COPY(&ethhdr->dest, &hdr->shwaddr);
00799 #endif /* LWIP_AUTOIP */
00800       ETHADDR16_COPY(&hdr->shwaddr, ethaddr);
00801       ETHADDR16_COPY(&ethhdr->src, ethaddr);
00802 
00803       /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
00804          are already correct, we tested that before */
00805 
00806       /* return ARP reply */
00807       netif->linkoutput(netif, p);
00808     /* we are not configured? */
00809     } else if (ip_addr_isany(&netif->ip_addr)) {
00810       /* { for_us == 0 and netif->ip_addr.addr == 0 } */
00811       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
00812     /* request was not directed to us */
00813     } else {
00814       /* { for_us == 0 and netif->ip_addr.addr != 0 } */
00815       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
00816     }
00817     break;
00818   case PP_HTONS(ARP_REPLY):
00819     /* ARP reply. We already updated the ARP cache earlier. */
00820     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
00821 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
00822     /* DHCP wants to know about ARP replies from any host with an
00823      * IP address also offered to us by the DHCP server. We do not
00824      * want to take a duplicate IP address on a single network.
00825      * @todo How should we handle redundant (fail-over) interfaces? */
00826     dhcp_arp_reply(netif, &sipaddr);
00827 #endif /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */
00828     break;
00829   default:
00830     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
00831     ETHARP_STATS_INC(etharp.err);
00832     break;
00833   }
00834   /* free ARP packet */
00835   pbuf_free(p);
00836 }
00837 
00838 /** Just a small helper function that sends a pbuf to an ethernet address
00839  * in the arp_table specified by the index 'arp_idx'.
00840  */
00841 static err_t
00842 etharp_output_to_arp_index(struct netif *netif, struct pbuf *q, u8_t arp_idx)
00843 {
00844   LWIP_ASSERT("arp_table[arp_idx].state >= ETHARP_STATE_STABLE",
00845               arp_table[arp_idx].state >= ETHARP_STATE_STABLE);
00846   /* if arp table entry is about to expire: re-request it,
00847      but only if its state is ETHARP_STATE_STABLE to prevent flooding the
00848      network with ARP requests if this address is used frequently. */
00849   if ((arp_table[arp_idx].state == ETHARP_STATE_STABLE) && 
00850       (arp_table[arp_idx].ctime >= ARP_AGE_REREQUEST_USED)) {
00851     if (etharp_request(netif, &arp_table[arp_idx].ipaddr) == ERR_OK) {
00852       arp_table[arp_idx].state = ETHARP_STATE_STABLE_REREQUESTING;
00853     }
00854   }
00855   
00856   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr),
00857     &arp_table[arp_idx].ethaddr);
00858 }
00859 
00860 /**
00861  * Resolve and fill-in Ethernet address header for outgoing IP packet.
00862  *
00863  * For IP multicast and broadcast, corresponding Ethernet addresses
00864  * are selected and the packet is transmitted on the link.
00865  *
00866  * For unicast addresses, the packet is submitted to etharp_query(). In
00867  * case the IP address is outside the local network, the IP address of
00868  * the gateway is used.
00869  *
00870  * @param netif The lwIP network interface which the IP packet will be sent on.
00871  * @param q The pbuf(s) containing the IP packet to be sent.
00872  * @param ipaddr The IP address of the packet destination.
00873  *
00874  * @return
00875  * - ERR_RTE No route to destination (no gateway to external networks),
00876  * or the return type of either etharp_query() or etharp_send_ip().
00877  */
00878 err_t
00879 etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
00880 {
00881   struct eth_addr *dest;
00882   struct eth_addr mcastaddr;
00883   ip_addr_t *dst_addr = ipaddr;
00884 
00885   LWIP_ASSERT("netif != NULL", netif != NULL);
00886   LWIP_ASSERT("q != NULL", q != NULL);
00887   LWIP_ASSERT("ipaddr != NULL", ipaddr != NULL);
00888 
00889   /* make room for Ethernet header - should not fail */
00890   if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
00891     /* bail out */
00892     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
00893       ("etharp_output: could not allocate room for header.\n"));
00894     LINK_STATS_INC(link.lenerr);
00895     return ERR_BUF;
00896   }
00897 
00898   /* Determine on destination hardware address. Broadcasts and multicasts
00899    * are special, other IP addresses are looked up in the ARP table. */
00900 
00901   /* broadcast destination IP address? */
00902   if (ip_addr_isbroadcast(ipaddr, netif)) {
00903     /* broadcast on Ethernet also */
00904     dest = (struct eth_addr *)&ethbroadcast;
00905   /* multicast destination IP address? */
00906   } else if (ip_addr_ismulticast(ipaddr)) {
00907     /* Hash IP multicast address to MAC address.*/
00908     mcastaddr.addr[0] = LL_MULTICAST_ADDR_0;
00909     mcastaddr.addr[1] = LL_MULTICAST_ADDR_1;
00910     mcastaddr.addr[2] = LL_MULTICAST_ADDR_2;
00911     mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
00912     mcastaddr.addr[4] = ip4_addr3(ipaddr);
00913     mcastaddr.addr[5] = ip4_addr4(ipaddr);
00914     /* destination Ethernet address is multicast */
00915     dest = &mcastaddr;
00916   /* unicast destination IP address? */
00917   } else {
00918     s8_t i;
00919     /* outside local network? if so, this can neither be a global broadcast nor
00920        a subnet broadcast. */
00921     if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask)) &&
00922         !ip_addr_islinklocal(ipaddr)) {
00923 #if LWIP_AUTOIP
00924       struct ip_hdr *iphdr = (struct ip_hdr*)((u8_t*)q->payload +
00925         sizeof(struct eth_hdr));
00926       /* According to RFC 3297, chapter 2.6.2 (Forwarding Rules), a packet with
00927          a link-local source address must always be "directly to its destination
00928          on the same physical link. The host MUST NOT send the packet to any
00929          router for forwarding". */
00930       if (!ip_addr_islinklocal(&iphdr->src))
00931 #endif /* LWIP_AUTOIP */
00932       {
00933         /* interface has default gateway? */
00934         if (!ip_addr_isany(&netif->gw)) {
00935           /* send to hardware address of default gateway IP address */
00936           dst_addr = &(netif->gw);
00937         /* no default gateway available */
00938         } else {
00939           /* no route to destination error (default gateway missing) */
00940           return ERR_RTE;
00941         }
00942       }
00943     }
00944 #if LWIP_NETIF_HWADDRHINT
00945     if (netif->addr_hint != NULL) {
00946       /* per-pcb cached entry was given */
00947       u8_t etharp_cached_entry = *(netif->addr_hint);
00948       if (etharp_cached_entry < ARP_TABLE_SIZE) {
00949 #endif /* LWIP_NETIF_HWADDRHINT */
00950         if ((arp_table[etharp_cached_entry].state >= ETHARP_STATE_STABLE) &&
00951             (ip_addr_cmp(dst_addr, &arp_table[etharp_cached_entry].ipaddr))) {
00952           /* the per-pcb-cached entry is stable and the right one! */
00953           ETHARP_STATS_INC(etharp.cachehit);
00954           return etharp_output_to_arp_index(netif, q, etharp_cached_entry);
00955         }
00956 #if LWIP_NETIF_HWADDRHINT
00957       }
00958     }
00959 #endif /* LWIP_NETIF_HWADDRHINT */
00960 
00961     /* find stable entry: do this here since this is a critical path for
00962        throughput and etharp_find_entry() is kind of slow */
00963     for (i = 0; i < ARP_TABLE_SIZE; i++) {
00964       if ((arp_table[i].state >= ETHARP_STATE_STABLE) &&
00965           (ip_addr_cmp(dst_addr, &arp_table[i].ipaddr))) {
00966         /* found an existing, stable entry */
00967         ETHARP_SET_HINT(netif, i);
00968         return etharp_output_to_arp_index(netif, q, i);
00969       }
00970     }
00971     /* no stable entry found, use the (slower) query function:
00972        queue on destination Ethernet address belonging to ipaddr */
00973     return etharp_query(netif, dst_addr, q);
00974   }
00975 
00976   /* continuation for multicast/broadcast destinations */
00977   /* obtain source Ethernet address of the given interface */
00978   /* send packet directly on the link */
00979   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
00980 }
00981 
00982 /**
00983  * Send an ARP request for the given IP address and/or queue a packet.
00984  *
00985  * If the IP address was not yet in the cache, a pending ARP cache entry
00986  * is added and an ARP request is sent for the given address. The packet
00987  * is queued on this entry.
00988  *
00989  * If the IP address was already pending in the cache, a new ARP request
00990  * is sent for the given address. The packet is queued on this entry.
00991  *
00992  * If the IP address was already stable in the cache, and a packet is
00993  * given, it is directly sent and no ARP request is sent out. 
00994  * 
00995  * If the IP address was already stable in the cache, and no packet is
00996  * given, an ARP request is sent out.
00997  * 
00998  * @param netif The lwIP network interface on which ipaddr
00999  * must be queried for.
01000  * @param ipaddr The IP address to be resolved.
01001  * @param q If non-NULL, a pbuf that must be delivered to the IP address.
01002  * q is not freed by this function.
01003  *
01004  * @note q must only be ONE packet, not a packet queue!
01005  *
01006  * @return
01007  * - ERR_BUF Could not make room for Ethernet header.
01008  * - ERR_MEM Hardware address unknown, and no more ARP entries available
01009  *   to query for address or queue the packet.
01010  * - ERR_MEM Could not queue packet due to memory shortage.
01011  * - ERR_RTE No route to destination (no gateway to external networks).
01012  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
01013  *
01014  */
01015 err_t
01016 etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
01017 {
01018   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
01019   err_t result = ERR_MEM;
01020   s8_t i; /* ARP entry index */
01021 
01022   /* non-unicast address? */
01023   if (ip_addr_isbroadcast(ipaddr, netif) ||
01024       ip_addr_ismulticast(ipaddr) ||
01025       ip_addr_isany(ipaddr)) {
01026     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
01027     return ERR_ARG;
01028   }
01029 
01030   /* find entry in ARP cache, ask to create entry if queueing packet */
01031   i = etharp_find_entry(ipaddr, ETHARP_FLAG_TRY_HARD);
01032 
01033   /* could not find or create entry? */
01034   if (i < 0) {
01035     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
01036     if (q) {
01037       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
01038       ETHARP_STATS_INC(etharp.memerr);
01039     }
01040     return (err_t)i;
01041   }
01042 
01043   /* mark a fresh entry as pending (we just sent a request) */
01044   if (arp_table[i].state == ETHARP_STATE_EMPTY) {
01045     arp_table[i].state = ETHARP_STATE_PENDING;
01046   }
01047 
01048   /* { i is either a STABLE or (new or existing) PENDING entry } */
01049   LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
01050   ((arp_table[i].state == ETHARP_STATE_PENDING) ||
01051    (arp_table[i].state >= ETHARP_STATE_STABLE)));
01052 
01053   /* do we have a pending entry? or an implicit query request? */
01054   if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
01055     /* try to resolve it; send out ARP request */
01056     result = etharp_request(netif, ipaddr);
01057     if (result != ERR_OK) {
01058       /* ARP request couldn't be sent */
01059       /* We don't re-send arp request in etharp_tmr, but we still queue packets,
01060          since this failure could be temporary, and the next packet calling
01061          etharp_query again could lead to sending the queued packets. */
01062     }
01063     if (q == NULL) {
01064       return result;
01065     }
01066   }
01067 
01068   /* packet given? */
01069   LWIP_ASSERT("q != NULL", q != NULL);
01070   /* stable entry? */
01071   if (arp_table[i].state >= ETHARP_STATE_STABLE) {
01072     /* we have a valid IP->Ethernet address mapping */
01073     ETHARP_SET_HINT(netif, i);
01074     /* send the packet */
01075     result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
01076   /* pending entry? (either just created or already pending */
01077   } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
01078     /* entry is still pending, queue the given packet 'q' */
01079     struct pbuf *p;
01080     int copy_needed = 0;
01081     /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
01082      * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
01083      * PBUF_ROMs can be left as they are, since ROM must not get changed. */
01084     p = q;
01085     while (p) {
01086       LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
01087       if(p->type != PBUF_ROM) {
01088         copy_needed = 1;
01089         break;
01090       }
01091       p = p->next;
01092     }
01093     if(copy_needed) {
01094       /* copy the whole packet into new pbufs */
01095       p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
01096       if(p != NULL) {
01097         if (pbuf_copy(p, q) != ERR_OK) {
01098           pbuf_free(p);
01099           p = NULL;
01100         }
01101       }
01102     } else {
01103       /* referencing the old pbuf is enough */
01104       p = q;
01105       pbuf_ref(p);
01106     }
01107     /* packet could be taken over? */
01108     if (p != NULL) {
01109       /* queue packet ... */
01110 #if ARP_QUEUEING
01111       struct etharp_q_entry *new_entry;
01112       /* allocate a new arp queue entry */
01113       new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
01114       if (new_entry != NULL) {
01115         new_entry->next = 0;
01116         new_entry->p = p;
01117         if(arp_table[i].q != NULL) {
01118           /* queue was already existent, append the new entry to the end */
01119           struct etharp_q_entry *r;
01120           r = arp_table[i].q;
01121           while (r->next != NULL) {
01122             r = r->next;
01123           }
01124           r->next = new_entry;
01125         } else {
01126           /* queue did not exist, first item in queue */
01127           arp_table[i].q = new_entry;
01128         }
01129         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01130         result = ERR_OK;
01131       } else {
01132         /* the pool MEMP_ARP_QUEUE is empty */
01133         pbuf_free(p);
01134         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));
01135         result = ERR_MEM;
01136       }
01137 #else /* ARP_QUEUEING */
01138       /* always queue one packet per ARP request only, freeing a previously queued packet */
01139       if (arp_table[i].q != NULL) {
01140         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));
01141         pbuf_free(arp_table[i].q);
01142       }
01143       arp_table[i].q = p;
01144       result = ERR_OK;
01145       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01146 #endif /* ARP_QUEUEING */
01147     } else {
01148       ETHARP_STATS_INC(etharp.memerr);
01149       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));
01150       result = ERR_MEM;
01151     }
01152   }
01153   return result;
01154 }
01155 
01156 /**
01157  * Send a raw ARP packet (opcode and all addresses can be modified)
01158  *
01159  * @param netif the lwip network interface on which to send the ARP packet
01160  * @param ethsrc_addr the source MAC address for the ethernet header
01161  * @param ethdst_addr the destination MAC address for the ethernet header
01162  * @param hwsrc_addr the source MAC address for the ARP protocol header
01163  * @param ipsrc_addr the source IP address for the ARP protocol header
01164  * @param hwdst_addr the destination MAC address for the ARP protocol header
01165  * @param ipdst_addr the destination IP address for the ARP protocol header
01166  * @param opcode the type of the ARP packet
01167  * @return ERR_OK if the ARP packet has been sent
01168  *         ERR_MEM if the ARP packet couldn't be allocated
01169  *         any other err_t on failure
01170  */
01171 #if !LWIP_AUTOIP
01172 static
01173 #endif /* LWIP_AUTOIP */
01174 err_t
01175 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
01176            const struct eth_addr *ethdst_addr,
01177            const struct eth_addr *hwsrc_addr, const ip_addr_t *ipsrc_addr,
01178            const struct eth_addr *hwdst_addr, const ip_addr_t *ipdst_addr,
01179            const u16_t opcode)
01180 {
01181   struct pbuf *p;
01182   err_t result = ERR_OK;
01183   struct eth_hdr *ethhdr;
01184   struct etharp_hdr *hdr;
01185 #if LWIP_AUTOIP
01186   const u8_t * ethdst_hwaddr;
01187 #endif /* LWIP_AUTOIP */
01188 
01189   LWIP_ASSERT("netif != NULL", netif != NULL);
01190 
01191   /* allocate a pbuf for the outgoing ARP request packet */
01192   p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
01193   /* could allocate a pbuf for an ARP request? */
01194   if (p == NULL) {
01195     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
01196       ("etharp_raw: could not allocate pbuf for ARP request.\n"));
01197     ETHARP_STATS_INC(etharp.memerr);
01198     return ERR_MEM;
01199   }
01200   LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
01201               (p->len >= SIZEOF_ETHARP_PACKET));
01202 
01203   ethhdr = (struct eth_hdr *)p->payload;
01204   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
01205   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
01206   hdr->opcode = htons(opcode);
01207 
01208   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
01209               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
01210 #if LWIP_AUTOIP
01211   /* If we are using Link-Local, all ARP packets that contain a Link-Local
01212    * 'sender IP address' MUST be sent using link-layer broadcast instead of
01213    * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
01214   ethdst_hwaddr = ip_addr_islinklocal(ipsrc_addr) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
01215 #endif /* LWIP_AUTOIP */
01216   /* Write the ARP MAC-Addresses */
01217   ETHADDR16_COPY(&hdr->shwaddr, hwsrc_addr);
01218   ETHADDR16_COPY(&hdr->dhwaddr, hwdst_addr);
01219   /* Write the Ethernet MAC-Addresses */
01220 #if LWIP_AUTOIP
01221   ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
01222 #else  /* LWIP_AUTOIP */
01223   ETHADDR16_COPY(&ethhdr->dest, ethdst_addr);
01224 #endif /* LWIP_AUTOIP */
01225   ETHADDR16_COPY(&ethhdr->src, ethsrc_addr);
01226   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
01227    * structure packing. */ 
01228   IPADDR2_COPY(&hdr->sipaddr, ipsrc_addr);
01229   IPADDR2_COPY(&hdr->dipaddr, ipdst_addr);
01230 
01231   hdr->hwtype = PP_HTONS(HWTYPE_ETHERNET);
01232   hdr->proto = PP_HTONS(ETHTYPE_IP);
01233   /* set hwlen and protolen */
01234   hdr->hwlen = ETHARP_HWADDR_LEN;
01235   hdr->protolen = sizeof(ip_addr_t);
01236 
01237   ethhdr->type = PP_HTONS(ETHTYPE_ARP);
01238   /* send ARP query */
01239   result = netif->linkoutput(netif, p);
01240   ETHARP_STATS_INC(etharp.xmit);
01241   /* free ARP query packet */
01242   pbuf_free(p);
01243   p = NULL;
01244   /* could not allocate pbuf for ARP request */
01245 
01246   return result;
01247 }
01248 
01249 /**
01250  * Send an ARP request packet asking for ipaddr.
01251  *
01252  * @param netif the lwip network interface on which to send the request
01253  * @param ipaddr the IP address for which to ask
01254  * @return ERR_OK if the request has been sent
01255  *         ERR_MEM if the ARP packet couldn't be allocated
01256  *         any other err_t on failure
01257  */
01258 err_t
01259 etharp_request(struct netif *netif, ip_addr_t *ipaddr)
01260 {
01261   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
01262   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
01263                     (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
01264                     ipaddr, ARP_REQUEST);
01265 }
01266 #endif /* LWIP_ARP */
01267 
01268 /**
01269  * Process received ethernet frames. Using this function instead of directly
01270  * calling ip_input and passing ARP frames through etharp in ethernetif_input,
01271  * the ARP cache is protected from concurrent access.
01272  *
01273  * @param p the recevied packet, p->payload pointing to the ethernet header
01274  * @param netif the network interface on which the packet was received
01275  */
01276 err_t
01277 ethernet_input(struct pbuf *p, struct netif *netif)
01278 {
01279   struct eth_hdr* ethhdr;
01280   u16_t type;
01281 #if LWIP_ARP || ETHARP_SUPPORT_VLAN
01282   s16_t ip_hdr_offset = SIZEOF_ETH_HDR;
01283 #endif /* LWIP_ARP || ETHARP_SUPPORT_VLAN */
01284 
01285   if (p->len <= SIZEOF_ETH_HDR) {
01286     /* a packet with only an ethernet header (or less) is not valid for us */
01287     ETHARP_STATS_INC(etharp.proterr);
01288     ETHARP_STATS_INC(etharp.drop);
01289     goto free_and_return;
01290   }
01291 
01292   /* points to packet payload, which starts with an Ethernet header */
01293   ethhdr = (struct eth_hdr *)p->payload;
01294   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
01295     ("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",
01296      (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
01297      (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
01298      (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
01299      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
01300      (unsigned)htons(ethhdr->type)));
01301 
01302   type = ethhdr->type;
01303 #if ETHARP_SUPPORT_VLAN
01304   if (type == PP_HTONS(ETHTYPE_VLAN)) {
01305     struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
01306     if (p->len <= SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR) {
01307       /* a packet with only an ethernet/vlan header (or less) is not valid for us */
01308       ETHARP_STATS_INC(etharp.proterr);
01309       ETHARP_STATS_INC(etharp.drop);
01310       goto free_and_return;
01311     }
01312 #if defined(ETHARP_VLAN_CHECK) || defined(ETHARP_VLAN_CHECK_FN) /* if not, allow all VLANs */
01313 #ifdef ETHARP_VLAN_CHECK_FN
01314     if (!ETHARP_VLAN_CHECK_FN(ethhdr, vlan)) {
01315 #elif defined(ETHARP_VLAN_CHECK)
01316     if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
01317 #endif
01318       /* silently ignore this packet: not for our VLAN */
01319       pbuf_free(p);
01320       return ERR_OK;
01321     }
01322 #endif /* defined(ETHARP_VLAN_CHECK) || defined(ETHARP_VLAN_CHECK_FN) */
01323     type = vlan->tpid;
01324     ip_hdr_offset = SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR;
01325   }
01326 #endif /* ETHARP_SUPPORT_VLAN */
01327 
01328 #if LWIP_ARP_FILTER_NETIF
01329   netif = LWIP_ARP_FILTER_NETIF_FN(p, netif, htons(type));
01330 #endif /* LWIP_ARP_FILTER_NETIF*/
01331 
01332   if (ethhdr->dest.addr[0] & 1) {
01333     /* this might be a multicast or broadcast packet */
01334     if (ethhdr->dest.addr[0] == LL_MULTICAST_ADDR_0) {
01335       if ((ethhdr->dest.addr[1] == LL_MULTICAST_ADDR_1) &&
01336           (ethhdr->dest.addr[2] == LL_MULTICAST_ADDR_2)) {
01337         /* mark the pbuf as link-layer multicast */
01338         p->flags |= PBUF_FLAG_LLMCAST;
01339       }
01340     } else if (eth_addr_cmp(&ethhdr->dest, &ethbroadcast)) {
01341       /* mark the pbuf as link-layer broadcast */
01342       p->flags |= PBUF_FLAG_LLBCAST;
01343     }
01344   }
01345 
01346   switch (type) {
01347 #if LWIP_ARP
01348     /* IP packet? */
01349     case PP_HTONS(ETHTYPE_IP):
01350       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01351         goto free_and_return;
01352       }
01353 #if ETHARP_TRUST_IP_MAC
01354       /* update ARP table */
01355       etharp_ip_input(netif, p);
01356 #endif /* ETHARP_TRUST_IP_MAC */
01357       /* skip Ethernet header */
01358       if(pbuf_header(p, -ip_hdr_offset)) {
01359         LWIP_ASSERT("Can't move over header in packet", 0);
01360         goto free_and_return;
01361       } else {
01362         /* pass to IP layer */
01363         ip_input(p, netif);
01364       }
01365       break;
01366       
01367     case PP_HTONS(ETHTYPE_ARP):
01368       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01369         goto free_and_return;
01370       }
01371       /* pass p to ARP module */
01372       etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
01373       break;
01374 #endif /* LWIP_ARP */
01375 #if PPPOE_SUPPORT
01376     case PP_HTONS(ETHTYPE_PPPOEDISC): /* PPP Over Ethernet Discovery Stage */
01377       pppoe_disc_input(netif, p);
01378       break;
01379 
01380     case PP_HTONS(ETHTYPE_PPPOE): /* PPP Over Ethernet Session Stage */
01381       pppoe_data_input(netif, p);
01382       break;
01383 #endif /* PPPOE_SUPPORT */
01384 
01385     default:
01386       ETHARP_STATS_INC(etharp.proterr);
01387       ETHARP_STATS_INC(etharp.drop);
01388       goto free_and_return;
01389   }
01390 
01391   /* This means the pbuf is freed or consumed,
01392      so the caller doesn't have to free it again */
01393   return ERR_OK;
01394 
01395 free_and_return:
01396   pbuf_free(p);
01397   return ERR_OK;
01398 }
01399 #endif /* LWIP_ARP || LWIP_ETHERNET */