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_query(our_netif, its_ip_addr, NULL) upon
00012  * address change.
00013  */
00014 
00015 /*
00016  * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
00017  * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv>
00018  * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands.
00019  * All rights reserved.
00020  *
00021  * Redistribution and use in source and binary forms, with or without modification,
00022  * are permitted provided that the following conditions are met:
00023  *
00024  * 1. Redistributions of source code must retain the above copyright notice,
00025  *    this list of conditions and the following disclaimer.
00026  * 2. Redistributions in binary form must reproduce the above copyright notice,
00027  *    this list of conditions and the following disclaimer in the documentation
00028  *    and/or other materials provided with the distribution.
00029  * 3. The name of the author may not be used to endorse or promote products
00030  *    derived from this software without specific prior written permission.
00031  *
00032  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00033  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00034  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00035  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00036  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00037  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00038  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00039  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00040  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00041  * OF SUCH DAMAGE.
00042  *
00043  * This file is part of the lwIP TCP/IP stack.
00044  *
00045  */
00046  
00047 #include "lwip/opt.h"
00048 
00049 #if LWIP_ARP /* don't build if not configured for use in lwipopts.h */
00050 
00051 #include "lwip/inet.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 /** the time an ARP entry stays valid after its last update,
00066  *  for ARP_TMR_INTERVAL = 5000, this is
00067  *  (240 * 5) seconds = 20 minutes.
00068  */
00069 #define ARP_MAXAGE 240
00070 /** the time an ARP entry stays pending after first request,
00071  *  for ARP_TMR_INTERVAL = 5000, this is
00072  *  (2 * 5) seconds = 10 seconds.
00073  * 
00074  *  @internal Keep this number at least 2, otherwise it might
00075  *  run out instantly if the timeout occurs directly after a request.
00076  */
00077 #define ARP_MAXPENDING 2
00078 
00079 #define HWTYPE_ETHERNET 1
00080 
00081 #define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8)
00082 #define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff)
00083 
00084 #define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8))
00085 #define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8))
00086 
00087 enum etharp_state {
00088   ETHARP_STATE_EMPTY = 0,
00089   ETHARP_STATE_PENDING,
00090   ETHARP_STATE_STABLE
00091 };
00092 
00093 struct etharp_entry {
00094 #if ARP_QUEUEING
00095   /** 
00096    * Pointer to queue of pending outgoing packets on this ARP entry.
00097    */
00098   struct etharp_q_entry *q;
00099 #endif
00100   struct ip_addr ipaddr;
00101   struct eth_addr ethaddr;
00102   enum etharp_state state;
00103   u8_t ctime;
00104   struct netif *netif;
00105 };
00106 
00107 const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
00108 const struct eth_addr ethzero = {{0,0,0,0,0,0}};
00109 static struct etharp_entry arp_table[ARP_TABLE_SIZE] MEM_POSITION;
00110 #if !LWIP_NETIF_HWADDRHINT
00111 static u8_t etharp_cached_entry MEM_POSITION;
00112 #endif
00113 
00114 /**
00115  * Try hard to create a new entry - we want the IP address to appear in
00116  * the cache (even if this means removing an active entry or so). */
00117 #define ETHARP_TRY_HARD 1
00118 #define ETHARP_FIND_ONLY  2
00119 
00120 #if LWIP_NETIF_HWADDRHINT
00121 #define NETIF_SET_HINT(netif, hint)  if (((netif) != NULL) && ((netif)->addr_hint != NULL))  \
00122                                       *((netif)->addr_hint) = (hint);
00123 static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif);
00124 #else /* LWIP_NETIF_HWADDRHINT */
00125 static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags);
00126 #endif /* LWIP_NETIF_HWADDRHINT */
00127 
00128 static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags);
00129 
00130 
00131 /* Some checks, instead of etharp_init(): */
00132 #if (LWIP_ARP && (ARP_TABLE_SIZE > 0x7f))
00133   #error "If you want to use ARP, ARP_TABLE_SIZE must fit in an s8_t, so, you have to reduce it in your lwipopts.h"
00134 #endif
00135 
00136 
00137 #if ARP_QUEUEING
00138 /**
00139  * Free a complete queue of etharp entries
00140  *
00141  * @param q a qeueue of etharp_q_entry's to free
00142  */
00143 static void
00144 free_etharp_q(struct etharp_q_entry *q)
00145 {
00146   struct etharp_q_entry *r;
00147   LWIP_ASSERT("q != NULL", q != NULL);
00148   LWIP_ASSERT("q->p != NULL", q->p != NULL);
00149   while (q) {
00150     r = q;
00151     q = q->next;
00152     LWIP_ASSERT("r->p != NULL", (r->p != NULL));
00153     pbuf_free(r->p);
00154     memp_free(MEMP_ARP_QUEUE, r);
00155   }
00156 }
00157 #endif
00158 
00159 /**
00160  * Clears expired entries in the ARP table.
00161  *
00162  * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
00163  * in order to expire entries in the ARP table.
00164  */
00165 void
00166 etharp_tmr(void)
00167 {
00168   u8_t i;
00169 
00170   LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
00171   /* remove expired entries from the ARP table */
00172   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00173     arp_table[i].ctime++;
00174     if (((arp_table[i].state == ETHARP_STATE_STABLE) &&
00175          (arp_table[i].ctime >= ARP_MAXAGE)) ||
00176         ((arp_table[i].state == ETHARP_STATE_PENDING)  &&
00177          (arp_table[i].ctime >= ARP_MAXPENDING))) {
00178          /* pending or stable entry has become old! */
00179       LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
00180            arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
00181       /* clean up entries that have just been expired */
00182       /* remove from SNMP ARP index tree */
00183       snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00184 #if ARP_QUEUEING
00185       /* and empty packet queue */
00186       if (arp_table[i].q != NULL) {
00187         /* remove all queued packets */
00188         LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
00189         free_etharp_q(arp_table[i].q);
00190         arp_table[i].q = NULL;
00191       }
00192 #endif
00193       /* recycle entry for re-use */      
00194       arp_table[i].state = ETHARP_STATE_EMPTY;
00195     }
00196 #if ARP_QUEUEING
00197     /* still pending entry? (not expired) */
00198     if (arp_table[i].state == ETHARP_STATE_PENDING) {
00199         /* resend an ARP query here? */
00200     }
00201 #endif
00202   }
00203 }
00204 
00205 /**
00206  * Search the ARP table for a matching or new entry.
00207  * 
00208  * If an IP address is given, return a pending or stable ARP entry that matches
00209  * the address. If no match is found, create a new entry with this address set,
00210  * but in state ETHARP_EMPTY. The caller must check and possibly change the
00211  * state of the returned entry.
00212  * 
00213  * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
00214  * 
00215  * In all cases, attempt to create new entries from an empty entry. If no
00216  * empty entries are available and ETHARP_TRY_HARD flag is set, recycle
00217  * old entries. Heuristic choose the least important entry for recycling.
00218  *
00219  * @param ipaddr IP address to find in ARP cache, or to add if not found.
00220  * @param flags
00221  * - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of
00222  * active (stable or pending) entries.
00223  *  
00224  * @return The ARP entry index that matched or is created, ERR_MEM if no
00225  * entry is found or could be recycled.
00226  */
00227 static s8_t
00228 #if LWIP_NETIF_HWADDRHINT
00229 find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif)
00230 #else /* LWIP_NETIF_HWADDRHINT */
00231 find_entry(struct ip_addr *ipaddr, u8_t flags)
00232 #endif /* LWIP_NETIF_HWADDRHINT */
00233 {
00234   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
00235   s8_t empty = ARP_TABLE_SIZE;
00236   u8_t i = 0, age_pending = 0, age_stable = 0;
00237 #if ARP_QUEUEING
00238   /* oldest entry with packets on queue */
00239   s8_t old_queue = ARP_TABLE_SIZE;
00240   /* its age */
00241   u8_t age_queue = 0;
00242 #endif
00243 
00244   /* First, test if the last call to this function asked for the
00245    * same address. If so, we're really fast! */
00246   if (ipaddr) {
00247     /* ipaddr to search for was given */
00248 #if LWIP_NETIF_HWADDRHINT
00249     if ((netif != NULL) && (netif->addr_hint != NULL)) {
00250       /* per-pcb cached entry was given */
00251       u8_t per_pcb_cache = *(netif->addr_hint);
00252       if ((per_pcb_cache < ARP_TABLE_SIZE) && arp_table[per_pcb_cache].state == ETHARP_STATE_STABLE) {
00253         /* the per-pcb-cached entry is stable */
00254         if (ip_addr_cmp(ipaddr, &arp_table[per_pcb_cache].ipaddr)) {
00255           /* per-pcb cached entry was the right one! */
00256           ETHARP_STATS_INC(etharp.cachehit);
00257           return per_pcb_cache;
00258         }
00259       }
00260     }
00261 #else /* #if LWIP_NETIF_HWADDRHINT */
00262     if (arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) {
00263       /* the cached entry is stable */
00264       if (ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr)) {
00265         /* cached entry was the right one! */
00266         ETHARP_STATS_INC(etharp.cachehit);
00267         return etharp_cached_entry;
00268       }
00269     }
00270 #endif /* #if LWIP_NETIF_HWADDRHINT */
00271   }
00272 
00273   /**
00274    * a) do a search through the cache, remember candidates
00275    * b) select candidate entry
00276    * c) create new entry
00277    */
00278 
00279   /* a) in a single search sweep, do all of this
00280    * 1) remember the first empty entry (if any)
00281    * 2) remember the oldest stable entry (if any)
00282    * 3) remember the oldest pending entry without queued packets (if any)
00283    * 4) remember the oldest pending entry with queued packets (if any)
00284    * 5) search for a matching IP entry, either pending or stable
00285    *    until 5 matches, or all entries are searched for.
00286    */
00287 
00288   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00289     /* no empty entry found yet and now we do find one? */
00290     if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) {
00291       LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
00292       /* remember first empty entry */
00293       empty = i;
00294     }
00295     /* pending entry? */
00296     else if (arp_table[i].state == ETHARP_STATE_PENDING) {
00297       /* if given, does IP address match IP address in ARP entry? */
00298       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00299         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
00300         /* found exact IP address match, simply bail out */
00301 #if LWIP_NETIF_HWADDRHINT
00302         NETIF_SET_HINT(netif, i);
00303 #else /* #if LWIP_NETIF_HWADDRHINT */
00304         etharp_cached_entry = i;
00305 #endif /* #if LWIP_NETIF_HWADDRHINT */
00306         return i;
00307 #if ARP_QUEUEING
00308       /* pending with queued packets? */
00309       } else if (arp_table[i].q != NULL) {
00310         if (arp_table[i].ctime >= age_queue) {
00311           old_queue = i;
00312           age_queue = arp_table[i].ctime;
00313         }
00314 #endif
00315       /* pending without queued packets? */
00316       } else {
00317         if (arp_table[i].ctime >= age_pending) {
00318           old_pending = i;
00319           age_pending = arp_table[i].ctime;
00320         }
00321       }        
00322     }
00323     /* stable entry? */
00324     else if (arp_table[i].state == ETHARP_STATE_STABLE) {
00325       /* if given, does IP address match IP address in ARP entry? */
00326       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00327         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
00328         /* found exact IP address match, simply bail out */
00329 #if LWIP_NETIF_HWADDRHINT
00330         NETIF_SET_HINT(netif, i);
00331 #else /* #if LWIP_NETIF_HWADDRHINT */
00332         etharp_cached_entry = i;
00333 #endif /* #if LWIP_NETIF_HWADDRHINT */
00334         return i;
00335       /* remember entry with oldest stable entry in oldest, its age in maxtime */
00336       } else if (arp_table[i].ctime >= age_stable) {
00337         old_stable = i;
00338         age_stable = arp_table[i].ctime;
00339       }
00340     }
00341   }
00342   /* { we have no match } => try to create a new entry */
00343    
00344   /* no empty entry found and not allowed to recycle? */
00345   if (((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0))
00346       /* or don't create new entry, only search? */
00347       || ((flags & ETHARP_FIND_ONLY) != 0)) {
00348     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
00349     return (s8_t)ERR_MEM;
00350   }
00351   
00352   /* b) choose the least destructive entry to recycle:
00353    * 1) empty entry
00354    * 2) oldest stable entry
00355    * 3) oldest pending entry without queued packets
00356    * 4) oldest pending entry with queued packets
00357    * 
00358    * { ETHARP_TRY_HARD is set at this point }
00359    */ 
00360 
00361   /* 1) empty entry available? */
00362   if (empty < ARP_TABLE_SIZE) {
00363     i = empty;
00364     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
00365   }
00366   /* 2) found recyclable stable entry? */
00367   else if (old_stable < ARP_TABLE_SIZE) {
00368     /* recycle oldest stable*/
00369     i = old_stable;
00370     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
00371 #if ARP_QUEUEING
00372     /* no queued packets should exist on stable entries */
00373     LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
00374 #endif
00375   /* 3) found recyclable pending entry without queued packets? */
00376   } else if (old_pending < ARP_TABLE_SIZE) {
00377     /* recycle oldest pending */
00378     i = old_pending;
00379     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
00380 #if ARP_QUEUEING
00381   /* 4) found recyclable pending entry with queued packets? */
00382   } else if (old_queue < ARP_TABLE_SIZE) {
00383     /* recycle oldest pending */
00384     i = old_queue;
00385     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)));
00386     free_etharp_q(arp_table[i].q);
00387     arp_table[i].q = NULL;
00388 #endif
00389     /* no empty or recyclable entries found */
00390   } else {
00391     return (s8_t)ERR_MEM;
00392   }
00393 
00394   /* { empty or recyclable entry found } */
00395   LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00396 
00397   if (arp_table[i].state != ETHARP_STATE_EMPTY)
00398   {
00399     snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00400   }
00401   /* recycle entry (no-op for an already empty entry) */
00402   arp_table[i].state = ETHARP_STATE_EMPTY;
00403 
00404   /* IP address given? */
00405   if (ipaddr != NULL) {
00406     /* set IP address */
00407     ip_addr_set(&arp_table[i].ipaddr, ipaddr);
00408   }
00409   arp_table[i].ctime = 0;
00410 #if LWIP_NETIF_HWADDRHINT
00411   NETIF_SET_HINT(netif, i);
00412 #else /* #if LWIP_NETIF_HWADDRHINT */
00413   etharp_cached_entry = i;
00414 #endif /* #if LWIP_NETIF_HWADDRHINT */
00415   return (err_t)i;
00416 }
00417 
00418 /**
00419  * Send an IP packet on the network using netif->linkoutput
00420  * The ethernet header is filled in before sending.
00421  *
00422  * @params netif the lwIP network interface on which to send the packet
00423  * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
00424  * @params src the source MAC address to be copied into the ethernet header
00425  * @params dst the destination MAC address to be copied into the ethernet header
00426  * @return ERR_OK if the packet was sent, any other err_t on failure
00427  */
00428 static err_t
00429 etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
00430 {
00431   struct eth_hdr *ethhdr = (struct eth_hdr *)p->payload;
00432   u8_t k;
00433 
00434   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00435               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00436   k = ETHARP_HWADDR_LEN;
00437   while(k > 0) {
00438     k--;
00439     ethhdr->dest.addr[k] = dst->addr[k];
00440     ethhdr->src.addr[k]  = src->addr[k];
00441   }
00442   ethhdr->type = htons(ETHTYPE_IP);
00443   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
00444   /* send the packet */
00445   return netif->linkoutput(netif, p);
00446 }
00447 
00448 /**
00449  * Update (or insert) a IP/MAC address pair in the ARP cache.
00450  *
00451  * If a pending entry is resolved, any queued packets will be sent
00452  * at this point.
00453  * 
00454  * @param ipaddr IP address of the inserted ARP entry.
00455  * @param ethaddr Ethernet address of the inserted ARP entry.
00456  * @param flags Defines behaviour:
00457  * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
00458  * only existing ARP entries will be updated.
00459  *
00460  * @return
00461  * - ERR_OK Succesfully updated ARP cache.
00462  * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
00463  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00464  *
00465  * @see pbuf_free()
00466  */
00467 static err_t
00468 update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
00469 {
00470   s8_t i;
00471   u8_t k;
00472   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 3, ("update_arp_entry()\n"));
00473   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
00474   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",
00475                                         ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr), 
00476                                         ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00477                                         ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00478   /* non-unicast address? */
00479   if (ip_addr_isany(ipaddr) ||
00480       ip_addr_isbroadcast(ipaddr, netif) ||
00481       ip_addr_ismulticast(ipaddr)) {
00482     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
00483     return ERR_ARG;
00484   }
00485   /* find or create ARP entry */
00486 #if LWIP_NETIF_HWADDRHINT
00487   i = find_entry(ipaddr, flags, netif);
00488 #else /* LWIP_NETIF_HWADDRHINT */
00489   i = find_entry(ipaddr, flags);
00490 #endif /* LWIP_NETIF_HWADDRHINT */
00491   /* bail out if no entry could be found */
00492   if (i < 0)
00493     return (err_t)i;
00494   
00495   /* mark it stable */
00496   arp_table[i].state = ETHARP_STATE_STABLE;
00497   /* record network interface */
00498   arp_table[i].netif = netif;
00499 
00500   /* insert in SNMP ARP index tree */
00501   snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
00502 
00503   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
00504   /* update address */
00505   k = ETHARP_HWADDR_LEN;
00506   while (k > 0) {
00507     k--;
00508     arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
00509   }
00510   /* reset time stamp */
00511   arp_table[i].ctime = 0;
00512 #if ARP_QUEUEING
00513   /* this is where we will send out queued packets! */
00514   while (arp_table[i].q != NULL) {
00515     struct pbuf *p;
00516     /* remember remainder of queue */
00517     struct etharp_q_entry *q = arp_table[i].q;
00518     /* pop first item off the queue */
00519     arp_table[i].q = q->next;
00520     /* get the packet pointer */
00521     p = q->p;
00522     /* now queue entry can be freed */
00523     memp_free(MEMP_ARP_QUEUE, q);
00524     /* send the queued IP packet */
00525     etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
00526     /* free the queued IP packet */
00527     pbuf_free(p);
00528   }
00529 #endif
00530   return ERR_OK;
00531 }
00532 
00533 /**
00534  * Finds (stable) ethernet/IP address pair from ARP table
00535  * using interface and IP address index.
00536  * @note the addresses in the ARP table are in network order!
00537  *
00538  * @param netif points to interface index
00539  * @param ipaddr points to the (network order) IP address index
00540  * @param eth_ret points to return pointer
00541  * @param ip_ret points to return pointer
00542  * @return table index if found, -1 otherwise
00543  */
00544 s8_t
00545 etharp_find_addr(struct netif *netif, struct ip_addr *ipaddr,
00546          struct eth_addr **eth_ret, struct ip_addr **ip_ret)
00547 {
00548   s8_t i;
00549 
00550   LWIP_UNUSED_ARG(netif);
00551 
00552 #if LWIP_NETIF_HWADDRHINT
00553   i = find_entry(ipaddr, ETHARP_FIND_ONLY, NULL);
00554 #else /* LWIP_NETIF_HWADDRHINT */
00555   i = find_entry(ipaddr, ETHARP_FIND_ONLY);
00556 #endif /* LWIP_NETIF_HWADDRHINT */
00557   if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) {
00558       *eth_ret = &arp_table[i].ethaddr;
00559       *ip_ret = &arp_table[i].ipaddr;
00560       return i;
00561   }
00562   return -1;
00563 }
00564 
00565 /**
00566  * Updates the ARP table using the given IP packet.
00567  *
00568  * Uses the incoming IP packet's source address to update the
00569  * ARP cache for the local network. The function does not alter
00570  * or free the packet. This function must be called before the
00571  * packet p is passed to the IP layer.
00572  *
00573  * @param netif The lwIP network interface on which the IP packet pbuf arrived.
00574  * @param p The IP packet that arrived on netif.
00575  *
00576  * @return NULL
00577  *
00578  * @see pbuf_free()
00579  */
00580 void
00581 etharp_ip_input(struct netif *netif, struct pbuf *p)
00582 {
00583   struct ethip_hdr *hdr;
00584   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00585   /* Only insert an entry if the source IP address of the
00586      incoming IP packet comes from a host on the local network. */
00587   hdr = (struct ethip_hdr *)p->payload;
00588   /* source is not on the local network? */
00589   if (!ip_addr_netcmp(&(hdr->ip.src), &(netif->ip_addr), &(netif->netmask))) {
00590     /* do nothing */
00591     return;
00592   }
00593 
00594   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
00595   /* update ARP table */
00596   /* @todo We could use ETHARP_TRY_HARD if we think we are going to talk
00597    * back soon (for example, if the destination IP address is ours. */
00598   update_arp_entry(netif, &(hdr->ip.src), &(hdr->eth.src), 0);
00599 }
00600 
00601 
00602 /**
00603  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
00604  * send out queued IP packets. Updates cache with snooped address pairs.
00605  *
00606  * Should be called for incoming ARP packets. The pbuf in the argument
00607  * is freed by this function.
00608  *
00609  * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
00610  * @param ethaddr Ethernet address of netif.
00611  * @param p The ARP packet that arrived on netif. Is freed by this function.
00612  *
00613  * @return NULL
00614  *
00615  * @see pbuf_free()
00616  */
00617 void
00618 etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
00619 {
00620   struct etharp_hdr *hdr;
00621   /* these are aligned properly, whereas the ARP header fields might not be */
00622   struct ip_addr sipaddr, dipaddr;
00623   u8_t i;
00624   u8_t for_us;
00625 #if LWIP_AUTOIP
00626   const u8_t * ethdst_hwaddr;
00627 #endif /* LWIP_AUTOIP */
00628 
00629   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00630   
00631   /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
00632      since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
00633   if (p->len < sizeof(struct etharp_hdr)) {
00634     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 1, ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len, (s16_t)sizeof(struct etharp_hdr)));
00635     ETHARP_STATS_INC(etharp.lenerr);
00636     ETHARP_STATS_INC(etharp.drop);
00637     pbuf_free(p);
00638     return;
00639   }
00640 
00641   hdr = (struct etharp_hdr *)p->payload;
00642 
00643   /* RFC 826 "Packet Reception": */
00644   if ((hdr->hwtype != htons(HWTYPE_ETHERNET)) ||
00645       (hdr->_hwlen_protolen != htons((ETHARP_HWADDR_LEN << 8) | sizeof(struct ip_addr))) ||
00646       (hdr->proto != htons(ETHTYPE_IP)) ||
00647       (hdr->ethhdr.type != htons(ETHTYPE_ARP)))  {
00648     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 1,
00649       ("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
00650       hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr), hdr->ethhdr.type));
00651     ETHARP_STATS_INC(etharp.proterr);
00652     ETHARP_STATS_INC(etharp.drop);
00653     pbuf_free(p);
00654     return;
00655   }
00656   ETHARP_STATS_INC(etharp.recv);
00657 
00658 #if LWIP_AUTOIP
00659   /* We have to check if a host already has configured our random
00660    * created link local address and continously check if there is
00661    * a host with this IP-address so we can detect collisions */
00662   autoip_arp_reply(netif, hdr);
00663 #endif /* LWIP_AUTOIP */
00664 
00665   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00666    * structure packing (not using structure copy which breaks strict-aliasing rules). */
00667   SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
00668   SMEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
00669 
00670   /* this interface is not configured? */
00671   if (netif->ip_addr.addr == 0) {
00672     for_us = 0;
00673   } else {
00674     /* ARP packet directed to us? */
00675     for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr));
00676   }
00677 
00678   /* ARP message directed to us? */
00679   if (for_us) {
00680     /* add IP address in ARP cache; assume requester wants to talk to us.
00681      * can result in directly sending the queued packets for this host. */
00682     update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD);
00683   /* ARP message not directed to us? */
00684   } else {
00685     /* update the source IP address in the cache, if present */
00686     update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), 0);
00687   }
00688 
00689   /* now act on the message itself */
00690   switch (htons(hdr->opcode)) {
00691   /* ARP request? */
00692   case ARP_REQUEST:
00693     /* ARP request. If it asked for our address, we send out a
00694      * reply. In any case, we time-stamp any existing ARP entry,
00695      * and possiby send out an IP packet that was queued on it. */
00696 
00697     LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
00698     /* ARP request for our address? */
00699     if (for_us) {
00700 
00701       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
00702       /* Re-use pbuf to send ARP reply.
00703          Since we are re-using an existing pbuf, we can't call etharp_raw since
00704          that would allocate a new pbuf. */
00705       hdr->opcode = htons(ARP_REPLY);
00706 
00707       hdr->dipaddr = hdr->sipaddr;
00708       SMEMCPY(&hdr->sipaddr, &netif->ip_addr, sizeof(hdr->sipaddr));
00709 
00710       LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00711                   (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00712       i = ETHARP_HWADDR_LEN;
00713 #if LWIP_AUTOIP
00714       /* If we are using Link-Local, ARP packets must be broadcast on the
00715        * link layer. (See RFC3927 Section 2.5) */
00716       ethdst_hwaddr = ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
00717 #endif /* LWIP_AUTOIP */
00718 
00719       while(i > 0) {
00720         i--;
00721         hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
00722 #if LWIP_AUTOIP
00723         hdr->ethhdr.dest.addr[i] = ethdst_hwaddr[i];
00724 #else  /* LWIP_AUTOIP */
00725         hdr->ethhdr.dest.addr[i] = hdr->shwaddr.addr[i];
00726 #endif /* LWIP_AUTOIP */
00727         hdr->shwaddr.addr[i] = ethaddr->addr[i];
00728         hdr->ethhdr.src.addr[i] = ethaddr->addr[i];
00729       }
00730 
00731       /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
00732          are already correct, we tested that before */
00733 
00734       /* return ARP reply */
00735       netif->linkoutput(netif, p);
00736     /* we are not configured? */
00737     } else if (netif->ip_addr.addr == 0) {
00738       /* { for_us == 0 and netif->ip_addr.addr == 0 } */
00739       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
00740     /* request was not directed to us */
00741     } else {
00742       /* { for_us == 0 and netif->ip_addr.addr != 0 } */
00743       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
00744     }
00745     break;
00746   case ARP_REPLY:
00747     /* ARP reply. We already updated the ARP cache earlier. */
00748     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
00749 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
00750     /* DHCP wants to know about ARP replies from any host with an
00751      * IP address also offered to us by the DHCP server. We do not
00752      * want to take a duplicate IP address on a single network.
00753      * @todo How should we handle redundant (fail-over) interfaces? */
00754     dhcp_arp_reply(netif, &sipaddr);
00755 #endif
00756     break;
00757   default:
00758     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
00759     ETHARP_STATS_INC(etharp.err);
00760     break;
00761   }
00762   /* free ARP packet */
00763   pbuf_free(p);
00764 }
00765 
00766 /**
00767  * Resolve and fill-in Ethernet address header for outgoing IP packet.
00768  *
00769  * For IP multicast and broadcast, corresponding Ethernet addresses
00770  * are selected and the packet is transmitted on the link.
00771  *
00772  * For unicast addresses, the packet is submitted to etharp_query(). In
00773  * case the IP address is outside the local network, the IP address of
00774  * the gateway is used.
00775  *
00776  * @param netif The lwIP network interface which the IP packet will be sent on.
00777  * @param q The pbuf(s) containing the IP packet to be sent.
00778  * @param ipaddr The IP address of the packet destination.
00779  *
00780  * @return
00781  * - ERR_RTE No route to destination (no gateway to external networks),
00782  * or the return type of either etharp_query() or etharp_send_ip().
00783  */
00784 err_t
00785 etharp_output(struct netif *netif, struct pbuf *q, struct ip_addr *ipaddr)
00786 {
00787   struct eth_addr *dest, mcastaddr;
00788 
00789   /* make room for Ethernet header - should not fail */
00790   if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
00791     /* bail out */
00792     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n"));
00793     LINK_STATS_INC(link.lenerr);
00794     return ERR_BUF;
00795   }
00796 
00797   /* assume unresolved Ethernet address */
00798   dest = NULL;
00799   /* Determine on destination hardware address. Broadcasts and multicasts
00800    * are special, other IP addresses are looked up in the ARP table. */
00801 
00802   /* broadcast destination IP address? */
00803   if (ip_addr_isbroadcast(ipaddr, netif)) {
00804     /* broadcast on Ethernet also */
00805     dest = (struct eth_addr *)&ethbroadcast;
00806   /* multicast destination IP address? */
00807   } else if (ip_addr_ismulticast(ipaddr)) {
00808     /* Hash IP multicast address to MAC address.*/
00809     mcastaddr.addr[0] = 0x01;
00810     mcastaddr.addr[1] = 0x00;
00811     mcastaddr.addr[2] = 0x5e;
00812     mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
00813     mcastaddr.addr[4] = ip4_addr3(ipaddr);
00814     mcastaddr.addr[5] = ip4_addr4(ipaddr);
00815     /* destination Ethernet address is multicast */
00816     dest = &mcastaddr;
00817   /* unicast destination IP address? */
00818   } else {
00819     /* outside local network? */
00820     if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
00821       /* interface has default gateway? */
00822       if (netif->gw.addr != 0) {
00823         /* send to hardware address of default gateway IP address */
00824         ipaddr = &(netif->gw);
00825       /* no default gateway available */
00826       } else {
00827         /* no route to destination error (default gateway missing) */
00828         return ERR_RTE;
00829       }
00830     }
00831     /* queue on destination Ethernet address belonging to ipaddr */
00832     return etharp_query(netif, ipaddr, q);
00833   }
00834 
00835   /* continuation for multicast/broadcast destinations */
00836   /* obtain source Ethernet address of the given interface */
00837   /* send packet directly on the link */
00838   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
00839 }
00840 
00841 /**
00842  * Send an ARP request for the given IP address and/or queue a packet.
00843  *
00844  * If the IP address was not yet in the cache, a pending ARP cache entry
00845  * is added and an ARP request is sent for the given address. The packet
00846  * is queued on this entry.
00847  *
00848  * If the IP address was already pending in the cache, a new ARP request
00849  * is sent for the given address. The packet is queued on this entry.
00850  *
00851  * If the IP address was already stable in the cache, and a packet is
00852  * given, it is directly sent and no ARP request is sent out. 
00853  * 
00854  * If the IP address was already stable in the cache, and no packet is
00855  * given, an ARP request is sent out.
00856  * 
00857  * @param netif The lwIP network interface on which ipaddr
00858  * must be queried for.
00859  * @param ipaddr The IP address to be resolved.
00860  * @param q If non-NULL, a pbuf that must be delivered to the IP address.
00861  * q is not freed by this function.
00862  *
00863  * @note q must only be ONE packet, not a packet queue!
00864  *
00865  * @return
00866  * - ERR_BUF Could not make room for Ethernet header.
00867  * - ERR_MEM Hardware address unknown, and no more ARP entries available
00868  *   to query for address or queue the packet.
00869  * - ERR_MEM Could not queue packet due to memory shortage.
00870  * - ERR_RTE No route to destination (no gateway to external networks).
00871  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00872  *
00873  */
00874 err_t
00875 etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
00876 {
00877   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
00878   err_t result = ERR_MEM;
00879   s8_t i; /* ARP entry index */
00880 
00881   /* non-unicast address? */
00882   if (ip_addr_isbroadcast(ipaddr, netif) ||
00883       ip_addr_ismulticast(ipaddr) ||
00884       ip_addr_isany(ipaddr)) {
00885     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
00886     return ERR_ARG;
00887   }
00888 
00889   /* find entry in ARP cache, ask to create entry if queueing packet */
00890 #if LWIP_NETIF_HWADDRHINT
00891   i = find_entry(ipaddr, ETHARP_TRY_HARD, netif);
00892 #else /* LWIP_NETIF_HWADDRHINT */
00893   i = find_entry(ipaddr, ETHARP_TRY_HARD);
00894 #endif /* LWIP_NETIF_HWADDRHINT */
00895 
00896   /* could not find or create entry? */
00897   if (i < 0) {
00898     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
00899     if (q) {
00900       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
00901       ETHARP_STATS_INC(etharp.memerr);
00902     }
00903     return (err_t)i;
00904   }
00905 
00906   /* mark a fresh entry as pending (we just sent a request) */
00907   if (arp_table[i].state == ETHARP_STATE_EMPTY) {
00908     arp_table[i].state = ETHARP_STATE_PENDING;
00909   }
00910 
00911   /* { i is either a STABLE or (new or existing) PENDING entry } */
00912   LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
00913   ((arp_table[i].state == ETHARP_STATE_PENDING) ||
00914    (arp_table[i].state == ETHARP_STATE_STABLE)));
00915 
00916   /* do we have a pending entry? or an implicit query request? */
00917   if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
00918     /* try to resolve it; send out ARP request */
00919     result = etharp_request(netif, ipaddr);
00920     if (result != ERR_OK) {
00921       /* ARP request couldn't be sent */
00922       /* We don't re-send arp request in etharp_tmr, but we still queue packets,
00923          since this failure could be temporary, and the next packet calling
00924          etharp_query again could lead to sending the queued packets. */
00925     }
00926   }
00927   
00928   /* packet given? */
00929   if (q != NULL) {
00930     /* stable entry? */
00931     if (arp_table[i].state == ETHARP_STATE_STABLE) {
00932       /* we have a valid IP->Ethernet address mapping */
00933       /* send the packet */
00934       result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
00935     /* pending entry? (either just created or already pending */
00936     } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
00937 #if ARP_QUEUEING /* queue the given q packet */
00938       struct pbuf *p;
00939       int copy_needed = 0;
00940       /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
00941        * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
00942        * PBUF_ROMs can be left as they are, since ROM must not get changed. */
00943       p = q;
00944       while (p) {
00945         LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
00946         if(p->type != PBUF_ROM) {
00947           copy_needed = 1;
00948           break;
00949         }
00950         p = p->next;
00951       }
00952       if(copy_needed) {
00953         /* copy the whole packet into new pbufs */
00954         p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
00955         if(p != NULL) {
00956           if (pbuf_copy(p, q) != ERR_OK) {
00957             pbuf_free(p);
00958             p = NULL;
00959           }
00960         }
00961       } else {
00962         /* referencing the old pbuf is enough */
00963         p = q;
00964         pbuf_ref(p);
00965       }
00966       /* packet could be taken over? */
00967       if (p != NULL) {
00968         /* queue packet ... */
00969         struct etharp_q_entry *new_entry;
00970         /* allocate a new arp queue entry */
00971         new_entry = memp_malloc(MEMP_ARP_QUEUE);
00972         if (new_entry != NULL) {
00973           new_entry->next = 0;
00974           new_entry->p = p;
00975           if(arp_table[i].q != NULL) {
00976             /* queue was already existent, append the new entry to the end */
00977             struct etharp_q_entry *r;
00978             r = arp_table[i].q;
00979             while (r->next != NULL) {
00980               r = r->next;
00981             }
00982             r->next = new_entry;
00983           } else {
00984             /* queue did not exist, first item in queue */
00985             arp_table[i].q = new_entry;
00986           }
00987           LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
00988           result = ERR_OK;
00989         } else {
00990           /* the pool MEMP_ARP_QUEUE is empty */
00991           pbuf_free(p);
00992           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));
00993           /* { result == ERR_MEM } through initialization */
00994         }
00995       } else {
00996         ETHARP_STATS_INC(etharp.memerr);
00997         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));
00998         /* { result == ERR_MEM } through initialization */
00999       }
01000 #else /* ARP_QUEUEING == 0 */
01001       /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
01002       /* { result == ERR_MEM } through initialization */
01003       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
01004 #endif
01005     }
01006   }
01007   return result;
01008 }
01009 
01010 /**
01011  * Send a raw ARP packet (opcode and all addresses can be modified)
01012  *
01013  * @param netif the lwip network interface on which to send the ARP packet
01014  * @param ethsrc_addr the source MAC address for the ethernet header
01015  * @param ethdst_addr the destination MAC address for the ethernet header
01016  * @param hwsrc_addr the source MAC address for the ARP protocol header
01017  * @param ipsrc_addr the source IP address for the ARP protocol header
01018  * @param hwdst_addr the destination MAC address for the ARP protocol header
01019  * @param ipdst_addr the destination IP address for the ARP protocol header
01020  * @param opcode the type of the ARP packet
01021  * @return ERR_OK if the ARP packet has been sent
01022  *         ERR_MEM if the ARP packet couldn't be allocated
01023  *         any other err_t on failure
01024  */
01025 #if !LWIP_AUTOIP
01026 static
01027 #endif /* LWIP_AUTOIP */
01028 err_t
01029 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
01030            const struct eth_addr *ethdst_addr,
01031            const struct eth_addr *hwsrc_addr, const struct ip_addr *ipsrc_addr,
01032            const struct eth_addr *hwdst_addr, const struct ip_addr *ipdst_addr,
01033            const u16_t opcode)
01034 {
01035   struct pbuf *p;
01036   err_t result = ERR_OK;
01037   u8_t k; /* ARP entry index */
01038   struct etharp_hdr *hdr;
01039 #if LWIP_AUTOIP
01040   const u8_t * ethdst_hwaddr;
01041 #endif /* LWIP_AUTOIP */
01042 
01043   /* allocate a pbuf for the outgoing ARP request packet */
01044   p = pbuf_alloc(PBUF_RAW, sizeof(struct etharp_hdr), PBUF_RAM);
01045   /* could allocate a pbuf for an ARP request? */
01046   if (p == NULL) {
01047     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 2, ("etharp_raw: could not allocate pbuf for ARP request.\n"));
01048     ETHARP_STATS_INC(etharp.memerr);
01049     return ERR_MEM;
01050   }
01051   LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
01052               (p->len >= sizeof(struct etharp_hdr)));
01053 
01054   hdr = (struct etharp_hdr *)p->payload;
01055   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
01056   hdr->opcode = htons(opcode);
01057 
01058   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
01059               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
01060   k = ETHARP_HWADDR_LEN;
01061 #if LWIP_AUTOIP
01062   /* If we are using Link-Local, ARP packets must be broadcast on the
01063    * link layer. (See RFC3927 Section 2.5) */
01064   ethdst_hwaddr = ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
01065 #endif /* LWIP_AUTOIP */
01066   /* Write MAC-Addresses (combined loop for both headers) */
01067   while(k > 0) {
01068     k--;
01069     /* Write the ARP MAC-Addresses */
01070     hdr->shwaddr.addr[k] = hwsrc_addr->addr[k];
01071     hdr->dhwaddr.addr[k] = hwdst_addr->addr[k];
01072     /* Write the Ethernet MAC-Addresses */
01073 #if LWIP_AUTOIP
01074     hdr->ethhdr.dest.addr[k] = ethdst_hwaddr[k];
01075 #else  /* LWIP_AUTOIP */
01076     hdr->ethhdr.dest.addr[k] = ethdst_addr->addr[k];
01077 #endif /* LWIP_AUTOIP */
01078     hdr->ethhdr.src.addr[k]  = ethsrc_addr->addr[k];
01079   }
01080   hdr->sipaddr = *(struct ip_addr2 *)ipsrc_addr;
01081   hdr->dipaddr = *(struct ip_addr2 *)ipdst_addr;
01082 
01083   hdr->hwtype = htons(HWTYPE_ETHERNET);
01084   hdr->proto = htons(ETHTYPE_IP);
01085   /* set hwlen and protolen together */
01086   hdr->_hwlen_protolen = htons((ETHARP_HWADDR_LEN << 8) | sizeof(struct ip_addr));
01087 
01088   hdr->ethhdr.type = htons(ETHTYPE_ARP);
01089   /* send ARP query */
01090   result = netif->linkoutput(netif, p);
01091   ETHARP_STATS_INC(etharp.xmit);
01092   /* free ARP query packet */
01093   pbuf_free(p);
01094   p = NULL;
01095   /* could not allocate pbuf for ARP request */
01096 
01097   return result;
01098 }
01099 
01100 /**
01101  * Send an ARP request packet asking for ipaddr.
01102  *
01103  * @param netif the lwip network interface on which to send the request
01104  * @param ipaddr the IP address for which to ask
01105  * @return ERR_OK if the request has been sent
01106  *         ERR_MEM if the ARP packet couldn't be allocated
01107  *         any other err_t on failure
01108  */
01109 err_t
01110 etharp_request(struct netif *netif, struct ip_addr *ipaddr)
01111 {
01112   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
01113   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
01114                     (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
01115                     ipaddr, ARP_REQUEST);
01116 }
01117 
01118 /**
01119  * Process received ethernet frames. Using this function instead of directly
01120  * calling ip_input and passing ARP frames through etharp in ethernetif_input,
01121  * the ARP cache is protected from concurrent access.
01122  *
01123  * @param p the recevied packet, p->payload pointing to the ethernet header
01124  * @param netif the network interface on which the packet was received
01125  */
01126 err_t
01127 ethernet_input(struct pbuf *p, struct netif *netif)
01128 {
01129   struct eth_hdr* ethhdr;
01130 
01131   /* points to packet payload, which starts with an Ethernet header */
01132   ethhdr = (struct eth_hdr *)p->payload;
01133   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
01134     ("ethernet_input: dest:%02x:%02x:%02x:%02x:%02x:%02x, src:%02x:%02x:%02x:%02x:%02x:%02x, type:%2hx\n",
01135      (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
01136      (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
01137      (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
01138      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
01139      (unsigned)htons(ethhdr->type)));
01140 
01141   switch (htons(ethhdr->type)) {
01142     /* IP packet? */
01143     case ETHTYPE_IP:
01144 #if ETHARP_TRUST_IP_MAC
01145       /* update ARP table */
01146       etharp_ip_input(netif, p);
01147 #endif /* ETHARP_TRUST_IP_MAC */
01148       /* skip Ethernet header */
01149       if(pbuf_header(p, -(s16_t)sizeof(struct eth_hdr))) {
01150         LWIP_ASSERT("Can't move over header in packet", 0);
01151         pbuf_free(p);
01152         p = NULL;
01153       } else {
01154         /* pass to IP layer */
01155         ip_input(p, netif);
01156       }
01157       break;
01158       
01159     case ETHTYPE_ARP:
01160       /* pass p to ARP module */
01161       etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
01162       break;
01163 
01164 #if PPPOE_SUPPORT
01165     case ETHTYPE_PPPOEDISC: /* PPP Over Ethernet Discovery Stage */
01166       pppoe_disc_input(netif, p);
01167       break;
01168 
01169     case ETHTYPE_PPPOE: /* PPP Over Ethernet Session Stage */
01170       pppoe_data_input(netif, p);
01171       break;
01172 #endif /* PPPOE_SUPPORT */
01173 
01174     default:
01175       ETHARP_STATS_INC(etharp.proterr);
01176       ETHARP_STATS_INC(etharp.drop);
01177       pbuf_free(p);
01178       p = NULL;
01179       break;
01180   }
01181 
01182   /* This means the pbuf is freed or consumed,
01183      so the caller doesn't have to free it again */
01184   return ERR_OK;
01185 }
01186 #endif /* LWIP_ARP */