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 /* don't build if not configured for use in lwipopts.h */
00049 
00050 #include "lwip/inet.h"
00051 #include "lwip/ip.h"
00052 #include "lwip/stats.h"
00053 #include "lwip/snmp.h"
00054 #include "lwip/dhcp.h "
00055 #include "lwip/autoip.h"
00056 #include "netif/etharp.h"
00057 
00058 #if PPPOE_SUPPORT
00059 #include "netif/ppp_oe.h"
00060 #endif /* PPPOE_SUPPORT */
00061 
00062 #include <string.h>
00063 
00064 /** the time an ARP entry stays valid after its last update,
00065  *  for ARP_TMR_INTERVAL = 5000, this is
00066  *  (240 * 5) seconds = 20 minutes.
00067  */
00068 #define ARP_MAXAGE 240
00069 /** the time an ARP entry stays pending after first request,
00070  *  for ARP_TMR_INTERVAL = 5000, this is
00071  *  (2 * 5) seconds = 10 seconds.
00072  * 
00073  *  @internal Keep this number at least 2, otherwise it might
00074  *  run out instantly if the timeout occurs directly after a request.
00075  */
00076 #define ARP_MAXPENDING 2
00077 
00078 #define HWTYPE_ETHERNET 1
00079 
00080 #define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8)
00081 #define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff)
00082 
00083 #define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8))
00084 #define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8))
00085 
00086 enum etharp_state {
00087   ETHARP_STATE_EMPTY = 0,
00088   ETHARP_STATE_PENDING,
00089   ETHARP_STATE_STABLE
00090 };
00091 
00092 struct etharp_entry {
00093 #if ARP_QUEUEING
00094   /** 
00095    * Pointer to queue of pending outgoing packets on this ARP entry.
00096    */
00097   struct etharp_q_entry *q;
00098 #endif
00099   struct ip_addr ipaddr;
00100   struct eth_addr ethaddr;
00101   enum etharp_state state;
00102   u8_t ctime;
00103   struct netif *netif;
00104 };
00105 
00106 const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
00107 const struct eth_addr ethzero = {{0,0,0,0,0,0}};
00108 static struct etharp_entry arp_table[ARP_TABLE_SIZE] MEM_POSITION;
00109 #if !LWIP_NETIF_HWADDRHINT
00110 static u8_t etharp_cached_entry MEM_POSITION;
00111 #endif
00112 
00113 /**
00114  * Try hard to create a new entry - we want the IP address to appear in
00115  * the cache (even if this means removing an active entry or so). */
00116 #define ETHARP_TRY_HARD 1
00117 #define ETHARP_FIND_ONLY  2
00118 
00119 #if LWIP_NETIF_HWADDRHINT
00120 #define NETIF_SET_HINT(netif, hint)  if (((netif) != NULL) && ((netif)->addr_hint != NULL))  \
00121                                       *((netif)->addr_hint) = (hint);
00122 static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif);
00123 #else /* LWIP_NETIF_HWADDRHINT */
00124 static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags);
00125 #endif /* LWIP_NETIF_HWADDRHINT */
00126 
00127 static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags);
00128 
00129 
00130 /* Some checks, instead of etharp_init(): */
00131 #if (LWIP_ARP && (ARP_TABLE_SIZE > 0x7f))
00132   #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"
00133 #endif
00134 
00135 
00136 #if ARP_QUEUEING
00137 /**
00138  * Free a complete queue of etharp entries
00139  *
00140  * @param q a qeueue of etharp_q_entry's to free
00141  */
00142 static void
00143 free_etharp_q(struct etharp_q_entry *q)
00144 {
00145   struct etharp_q_entry *r;
00146   LWIP_ASSERT("q != NULL", q != NULL);
00147   LWIP_ASSERT("q->p != NULL", q->p != NULL);
00148   while (q) {
00149     r = q;
00150     q = q->next;
00151     LWIP_ASSERT("r->p != NULL", (r->p != NULL));
00152     pbuf_free(r->p);
00153     memp_free(MEMP_ARP_QUEUE, r);
00154   }
00155 }
00156 #endif
00157 
00158 /**
00159  * Clears expired entries in the ARP table.
00160  *
00161  * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
00162  * in order to expire entries in the ARP table.
00163  */
00164 void
00165 etharp_tmr(void)
00166 {
00167   u8_t i;
00168 
00169   LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
00170   /* remove expired entries from the ARP table */
00171   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00172     arp_table[i].ctime++;
00173     if (((arp_table[i].state == ETHARP_STATE_STABLE) &&
00174          (arp_table[i].ctime >= ARP_MAXAGE)) ||
00175         ((arp_table[i].state == ETHARP_STATE_PENDING)  &&
00176          (arp_table[i].ctime >= ARP_MAXPENDING))) {
00177          /* pending or stable entry has become old! */
00178       LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
00179            arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
00180       /* clean up entries that have just been expired */
00181       /* remove from SNMP ARP index tree */
00182       snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00183 #if ARP_QUEUEING
00184       /* and empty packet queue */
00185       if (arp_table[i].q != NULL) {
00186         /* remove all queued packets */
00187         LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
00188         free_etharp_q(arp_table[i].q);
00189         arp_table[i].q = NULL;
00190       }
00191 #endif
00192       /* recycle entry for re-use */      
00193       arp_table[i].state = ETHARP_STATE_EMPTY;
00194     }
00195 #if ARP_QUEUEING
00196     /* still pending entry? (not expired) */
00197     if (arp_table[i].state == ETHARP_STATE_PENDING) {
00198         /* resend an ARP query here? */
00199     }
00200 #endif
00201   }
00202 }
00203 
00204 /**
00205  * Search the ARP table for a matching or new entry.
00206  * 
00207  * If an IP address is given, return a pending or stable ARP entry that matches
00208  * the address. If no match is found, create a new entry with this address set,
00209  * but in state ETHARP_EMPTY. The caller must check and possibly change the
00210  * state of the returned entry.
00211  * 
00212  * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
00213  * 
00214  * In all cases, attempt to create new entries from an empty entry. If no
00215  * empty entries are available and ETHARP_TRY_HARD flag is set, recycle
00216  * old entries. Heuristic choose the least important entry for recycling.
00217  *
00218  * @param ipaddr IP address to find in ARP cache, or to add if not found.
00219  * @param flags
00220  * - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of
00221  * active (stable or pending) entries.
00222  *  
00223  * @return The ARP entry index that matched or is created, ERR_MEM if no
00224  * entry is found or could be recycled.
00225  */
00226 static s8_t
00227 #if LWIP_NETIF_HWADDRHINT
00228 find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif)
00229 #else /* LWIP_NETIF_HWADDRHINT */
00230 find_entry(struct ip_addr *ipaddr, u8_t flags)
00231 #endif /* LWIP_NETIF_HWADDRHINT */
00232 {
00233   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
00234   s8_t empty = ARP_TABLE_SIZE;
00235   u8_t i = 0, age_pending = 0, age_stable = 0;
00236 #if ARP_QUEUEING
00237   /* oldest entry with packets on queue */
00238   s8_t old_queue = ARP_TABLE_SIZE;
00239   /* its age */
00240   u8_t age_queue = 0;
00241 #endif
00242 
00243   /* First, test if the last call to this function asked for the
00244    * same address. If so, we're really fast! */
00245   if (ipaddr) {
00246     /* ipaddr to search for was given */
00247 #if LWIP_NETIF_HWADDRHINT
00248     if ((netif != NULL) && (netif->addr_hint != NULL)) {
00249       /* per-pcb cached entry was given */
00250       u8_t per_pcb_cache = *(netif->addr_hint);
00251       if ((per_pcb_cache < ARP_TABLE_SIZE) && arp_table[per_pcb_cache].state == ETHARP_STATE_STABLE) {
00252         /* the per-pcb-cached entry is stable */
00253         if (ip_addr_cmp(ipaddr, &arp_table[per_pcb_cache].ipaddr)) {
00254           /* per-pcb cached entry was the right one! */
00255           ETHARP_STATS_INC(etharp.cachehit);
00256           return per_pcb_cache;
00257         }
00258       }
00259     }
00260 #else /* #if LWIP_NETIF_HWADDRHINT */
00261     if (arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) {
00262       /* the cached entry is stable */
00263       if (ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr)) {
00264         /* cached entry was the right one! */
00265         ETHARP_STATS_INC(etharp.cachehit);
00266         return etharp_cached_entry;
00267       }
00268     }
00269 #endif /* #if LWIP_NETIF_HWADDRHINT */
00270   }
00271 
00272   /**
00273    * a) do a search through the cache, remember candidates
00274    * b) select candidate entry
00275    * c) create new entry
00276    */
00277 
00278   /* a) in a single search sweep, do all of this
00279    * 1) remember the first empty entry (if any)
00280    * 2) remember the oldest stable entry (if any)
00281    * 3) remember the oldest pending entry without queued packets (if any)
00282    * 4) remember the oldest pending entry with queued packets (if any)
00283    * 5) search for a matching IP entry, either pending or stable
00284    *    until 5 matches, or all entries are searched for.
00285    */
00286 
00287   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00288     /* no empty entry found yet and now we do find one? */
00289     if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) {
00290       LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
00291       /* remember first empty entry */
00292       empty = i;
00293     }
00294     /* pending entry? */
00295     else if (arp_table[i].state == ETHARP_STATE_PENDING) {
00296       /* if given, does IP address match IP address in ARP entry? */
00297       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00298         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
00299         /* found exact IP address match, simply bail out */
00300 #if LWIP_NETIF_HWADDRHINT
00301         NETIF_SET_HINT(netif, i);
00302 #else /* #if LWIP_NETIF_HWADDRHINT */
00303         etharp_cached_entry = i;
00304 #endif /* #if LWIP_NETIF_HWADDRHINT */
00305         return i;
00306 #if ARP_QUEUEING
00307       /* pending with queued packets? */
00308       } else if (arp_table[i].q != NULL) {
00309         if (arp_table[i].ctime >= age_queue) {
00310           old_queue = i;
00311           age_queue = arp_table[i].ctime;
00312         }
00313 #endif
00314       /* pending without queued packets? */
00315       } else {
00316         if (arp_table[i].ctime >= age_pending) {
00317           old_pending = i;
00318           age_pending = arp_table[i].ctime;
00319         }
00320       }        
00321     }
00322     /* stable entry? */
00323     else if (arp_table[i].state == ETHARP_STATE_STABLE) {
00324       /* if given, does IP address match IP address in ARP entry? */
00325       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00326         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
00327         /* found exact IP address match, simply bail out */
00328 #if LWIP_NETIF_HWADDRHINT
00329         NETIF_SET_HINT(netif, i);
00330 #else /* #if LWIP_NETIF_HWADDRHINT */
00331         etharp_cached_entry = i;
00332 #endif /* #if LWIP_NETIF_HWADDRHINT */
00333         return i;
00334       /* remember entry with oldest stable entry in oldest, its age in maxtime */
00335       } else if (arp_table[i].ctime >= age_stable) {
00336         old_stable = i;
00337         age_stable = arp_table[i].ctime;
00338       }
00339     }
00340   }
00341   /* { we have no match } => try to create a new entry */
00342    
00343   /* no empty entry found and not allowed to recycle? */
00344   if (((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0))
00345       /* or don't create new entry, only search? */
00346       || ((flags & ETHARP_FIND_ONLY) != 0)) {
00347     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
00348     return (s8_t)ERR_MEM;
00349   }
00350   
00351   /* b) choose the least destructive entry to recycle:
00352    * 1) empty entry
00353    * 2) oldest stable entry
00354    * 3) oldest pending entry without queued packets
00355    * 4) oldest pending entry with queued packets
00356    * 
00357    * { ETHARP_TRY_HARD is set at this point }
00358    */ 
00359 
00360   /* 1) empty entry available? */
00361   if (empty < ARP_TABLE_SIZE) {
00362     i = empty;
00363     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
00364   }
00365   /* 2) found recyclable stable entry? */
00366   else if (old_stable < ARP_TABLE_SIZE) {
00367     /* recycle oldest stable*/
00368     i = old_stable;
00369     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
00370 #if ARP_QUEUEING
00371     /* no queued packets should exist on stable entries */
00372     LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
00373 #endif
00374   /* 3) found recyclable pending entry without queued packets? */
00375   } else if (old_pending < ARP_TABLE_SIZE) {
00376     /* recycle oldest pending */
00377     i = old_pending;
00378     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
00379 #if ARP_QUEUEING
00380   /* 4) found recyclable pending entry with queued packets? */
00381   } else if (old_queue < ARP_TABLE_SIZE) {
00382     /* recycle oldest pending */
00383     i = old_queue;
00384     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)));
00385     free_etharp_q(arp_table[i].q);
00386     arp_table[i].q = NULL;
00387 #endif
00388     /* no empty or recyclable entries found */
00389   } else {
00390     return (s8_t)ERR_MEM;
00391   }
00392 
00393   /* { empty or recyclable entry found } */
00394   LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00395 
00396   if (arp_table[i].state != ETHARP_STATE_EMPTY)
00397   {
00398     snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00399   }
00400   /* recycle entry (no-op for an already empty entry) */
00401   arp_table[i].state = ETHARP_STATE_EMPTY;
00402 
00403   /* IP address given? */
00404   if (ipaddr != NULL) {
00405     /* set IP address */
00406     ip_addr_set(&arp_table[i].ipaddr, ipaddr);
00407   }
00408   arp_table[i].ctime = 0;
00409 #if LWIP_NETIF_HWADDRHINT
00410   NETIF_SET_HINT(netif, i);
00411 #else /* #if LWIP_NETIF_HWADDRHINT */
00412   etharp_cached_entry = i;
00413 #endif /* #if LWIP_NETIF_HWADDRHINT */
00414   return (err_t)i;
00415 }
00416 
00417 /**
00418  * Send an IP packet on the network using netif->linkoutput
00419  * The ethernet header is filled in before sending.
00420  *
00421  * @params netif the lwIP network interface on which to send the packet
00422  * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
00423  * @params src the source MAC address to be copied into the ethernet header
00424  * @params dst the destination MAC address to be copied into the ethernet header
00425  * @return ERR_OK if the packet was sent, any other err_t on failure
00426  */
00427 static err_t
00428 etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
00429 {
00430   struct eth_hdr *ethhdr = (struct eth_hdr *)p->payload;
00431   u8_t k;
00432 
00433   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00434               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00435   k = ETHARP_HWADDR_LEN;
00436   while(k > 0) {
00437     k--;
00438     ethhdr->dest.addr[k] = dst->addr[k];
00439     ethhdr->src.addr[k]  = src->addr[k];
00440   }
00441   ethhdr->type = htons(ETHTYPE_IP);
00442   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
00443   /* send the packet */
00444   return netif->linkoutput(netif, p);
00445 }
00446 
00447 /**
00448  * Update (or insert) a IP/MAC address pair in the ARP cache.
00449  *
00450  * If a pending entry is resolved, any queued packets will be sent
00451  * at this point.
00452  * 
00453  * @param ipaddr IP address of the inserted ARP entry.
00454  * @param ethaddr Ethernet address of the inserted ARP entry.
00455  * @param flags Defines behaviour:
00456  * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
00457  * only existing ARP entries will be updated.
00458  *
00459  * @return
00460  * - ERR_OK Succesfully updated ARP cache.
00461  * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
00462  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00463  *
00464  * @see pbuf_free()
00465  */
00466 static err_t
00467 update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
00468 {
00469   s8_t i;
00470   u8_t k;
00471   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 3, ("update_arp_entry()\n"));
00472   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
00473   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",
00474                                         ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr), 
00475                                         ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00476                                         ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00477   /* non-unicast address? */
00478   if (ip_addr_isany(ipaddr) ||
00479       ip_addr_isbroadcast(ipaddr, netif) ||
00480       ip_addr_ismulticast(ipaddr)) {
00481     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
00482     return ERR_ARG;
00483   }
00484   /* find or create ARP entry */
00485 #if LWIP_NETIF_HWADDRHINT
00486   i = find_entry(ipaddr, flags, netif);
00487 #else /* LWIP_NETIF_HWADDRHINT */
00488   i = find_entry(ipaddr, flags);
00489 #endif /* LWIP_NETIF_HWADDRHINT */
00490   /* bail out if no entry could be found */
00491   if (i < 0)
00492     return (err_t)i;
00493   
00494   /* mark it stable */
00495   arp_table[i].state = ETHARP_STATE_STABLE;
00496   /* record network interface */
00497   arp_table[i].netif = netif;
00498 
00499   /* insert in SNMP ARP index tree */
00500   snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
00501 
00502   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
00503   /* update address */
00504   k = ETHARP_HWADDR_LEN;
00505   while (k > 0) {
00506     k--;
00507     arp_table[i].ethaddr.addr[k] = ethaddr->addr[k];
00508   }
00509   /* reset time stamp */
00510   arp_table[i].ctime = 0;
00511 #if ARP_QUEUEING
00512   /* this is where we will send out queued packets! */
00513   while (arp_table[i].q != NULL) {
00514     struct pbuf *p;
00515     /* remember remainder of queue */
00516     struct etharp_q_entry *q = arp_table[i].q;
00517     /* pop first item off the queue */
00518     arp_table[i].q = q->next;
00519     /* get the packet pointer */
00520     p = q->p;
00521     /* now queue entry can be freed */
00522     memp_free(MEMP_ARP_QUEUE, q);
00523     /* send the queued IP packet */
00524     etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
00525     /* free the queued IP packet */
00526     pbuf_free(p);
00527   }
00528 #endif
00529   return ERR_OK;
00530 }
00531 
00532 /**
00533  * Finds (stable) ethernet/IP address pair from ARP table
00534  * using interface and IP address index.
00535  * @note the addresses in the ARP table are in network order!
00536  *
00537  * @param netif points to interface index
00538  * @param ipaddr points to the (network order) IP address index
00539  * @param eth_ret points to return pointer
00540  * @param ip_ret points to return pointer
00541  * @return table index if found, -1 otherwise
00542  */
00543 s8_t
00544 etharp_find_addr(struct netif *netif, struct ip_addr *ipaddr,
00545          struct eth_addr **eth_ret, struct ip_addr **ip_ret)
00546 {
00547   s8_t i;
00548 
00549   LWIP_UNUSED_ARG(netif);
00550 
00551 #if LWIP_NETIF_HWADDRHINT
00552   i = find_entry(ipaddr, ETHARP_FIND_ONLY, NULL);
00553 #else /* LWIP_NETIF_HWADDRHINT */
00554   i = find_entry(ipaddr, ETHARP_FIND_ONLY);
00555 #endif /* LWIP_NETIF_HWADDRHINT */
00556   if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) {
00557       *eth_ret = &arp_table[i].ethaddr;
00558       *ip_ret = &arp_table[i].ipaddr;
00559       return i;
00560   }
00561   return -1;
00562 }
00563 
00564 /**
00565  * Updates the ARP table using the given IP packet.
00566  *
00567  * Uses the incoming IP packet's source address to update the
00568  * ARP cache for the local network. The function does not alter
00569  * or free the packet. This function must be called before the
00570  * packet p is passed to the IP layer.
00571  *
00572  * @param netif The lwIP network interface on which the IP packet pbuf arrived.
00573  * @param p The IP packet that arrived on netif.
00574  *
00575  * @return NULL
00576  *
00577  * @see pbuf_free()
00578  */
00579 void
00580 etharp_ip_input(struct netif *netif, struct pbuf *p)
00581 {
00582   struct eth_hdr *ethhdr;
00583   struct ip_hdr *iphdr;
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   ethhdr = (struct eth_hdr *)p->payload;
00588   iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00589 #if ETHARP_SUPPORT_VLAN
00590   if (ethhdr->type == ETHTYPE_VLAN) {
00591     iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00592   }
00593 #endif /* ETHARP_SUPPORT_VLAN */
00594 
00595   /* source is not on the local network? */
00596   if (!ip_addr_netcmp(&(iphdr->src), &(netif->ip_addr), &(netif->netmask))) {
00597     /* do nothing */
00598     return;
00599   }
00600 
00601   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
00602   /* update ARP table */
00603   /* @todo We could use ETHARP_TRY_HARD if we think we are going to talk
00604    * back soon (for example, if the destination IP address is ours. */
00605   update_arp_entry(netif, &(iphdr->src), &(ethhdr->src), 0);
00606 }
00607 
00608 
00609 /**
00610  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
00611  * send out queued IP packets. Updates cache with snooped address pairs.
00612  *
00613  * Should be called for incoming ARP packets. The pbuf in the argument
00614  * is freed by this function.
00615  *
00616  * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
00617  * @param ethaddr Ethernet address of netif.
00618  * @param p The ARP packet that arrived on netif. Is freed by this function.
00619  *
00620  * @return NULL
00621  *
00622  * @see pbuf_free()
00623  */
00624 void
00625 etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
00626 {
00627   struct etharp_hdr *hdr;
00628   struct eth_hdr *ethhdr;
00629   /* these are aligned properly, whereas the ARP header fields might not be */
00630   struct ip_addr sipaddr, dipaddr;
00631   u8_t i;
00632   u8_t for_us;
00633 #if LWIP_AUTOIP
00634   const u8_t * ethdst_hwaddr;
00635 #endif /* LWIP_AUTOIP */
00636 
00637   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00638   
00639   /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
00640      since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
00641   if (p->len < SIZEOF_ETHARP_PACKET) {
00642     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_ETHARP_PACKET));
00643     ETHARP_STATS_INC(etharp.lenerr);
00644     ETHARP_STATS_INC(etharp.drop);
00645     pbuf_free(p);
00646     return;
00647   }
00648 
00649   ethhdr = (struct eth_hdr *)p->payload;
00650   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00651 #if ETHARP_SUPPORT_VLAN
00652   if (ethhdr->type == ETHTYPE_VLAN) {
00653     hdr = (struct etharp_hdr *)(((u8_t*)ethhdr) + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00654   }
00655 #endif /* ETHARP_SUPPORT_VLAN */
00656 
00657   /* RFC 826 "Packet Reception": */
00658   if ((hdr->hwtype != htons(HWTYPE_ETHERNET)) ||
00659       (hdr->_hwlen_protolen != htons((ETHARP_HWADDR_LEN << 8) | sizeof(struct ip_addr))) ||
00660       (hdr->proto != htons(ETHTYPE_IP)) ||
00661       (ethhdr->type != htons(ETHTYPE_ARP)))  {
00662     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 1,
00663       ("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",
00664       hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr), ethhdr->type));
00665     ETHARP_STATS_INC(etharp.proterr);
00666     ETHARP_STATS_INC(etharp.drop);
00667     pbuf_free(p);
00668     return;
00669   }
00670   ETHARP_STATS_INC(etharp.recv);
00671 
00672 #if LWIP_AUTOIP
00673   /* We have to check if a host already has configured our random
00674    * created link local address and continously check if there is
00675    * a host with this IP-address so we can detect collisions */
00676   autoip_arp_reply(netif, hdr);
00677 #endif /* LWIP_AUTOIP */
00678 
00679   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00680    * structure packing (not using structure copy which breaks strict-aliasing rules). */
00681   SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
00682   SMEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
00683 
00684   /* this interface is not configured? */
00685   if (netif->ip_addr.addr == 0) {
00686     for_us = 0;
00687   } else {
00688     /* ARP packet directed to us? */
00689     for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr));
00690   }
00691 
00692   /* ARP message directed to us? */
00693   if (for_us) {
00694     /* add IP address in ARP cache; assume requester wants to talk to us.
00695      * can result in directly sending the queued packets for this host. */
00696     update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD);
00697   /* ARP message not directed to us? */
00698   } else {
00699     /* update the source IP address in the cache, if present */
00700     update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), 0);
00701   }
00702 
00703   /* now act on the message itself */
00704   switch (htons(hdr->opcode)) {
00705   /* ARP request? */
00706   case ARP_REQUEST:
00707     /* ARP request. If it asked for our address, we send out a
00708      * reply. In any case, we time-stamp any existing ARP entry,
00709      * and possiby send out an IP packet that was queued on it. */
00710 
00711     LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
00712     /* ARP request for our address? */
00713     if (for_us) {
00714 
00715       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
00716       /* Re-use pbuf to send ARP reply.
00717          Since we are re-using an existing pbuf, we can't call etharp_raw since
00718          that would allocate a new pbuf. */
00719       hdr->opcode = htons(ARP_REPLY);
00720 
00721       hdr->dipaddr = hdr->sipaddr;
00722       SMEMCPY(&hdr->sipaddr, &netif->ip_addr, sizeof(hdr->sipaddr));
00723 
00724       LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00725                   (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00726       i = ETHARP_HWADDR_LEN;
00727 #if LWIP_AUTOIP
00728       /* If we are using Link-Local, ARP packets must be broadcast on the
00729        * link layer. (See RFC3927 Section 2.5) */
00730       ethdst_hwaddr = ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
00731 #endif /* LWIP_AUTOIP */
00732 
00733       while(i > 0) {
00734         i--;
00735         hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i];
00736 #if LWIP_AUTOIP
00737         ethhdr->dest.addr[i] = ethdst_hwaddr[i];
00738 #else  /* LWIP_AUTOIP */
00739         ethhdr->dest.addr[i] = hdr->shwaddr.addr[i];
00740 #endif /* LWIP_AUTOIP */
00741         hdr->shwaddr.addr[i] = ethaddr->addr[i];
00742         ethhdr->src.addr[i] = ethaddr->addr[i];
00743       }
00744 
00745       /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
00746          are already correct, we tested that before */
00747 
00748       /* return ARP reply */
00749       netif->linkoutput(netif, p);
00750     /* we are not configured? */
00751     } else if (netif->ip_addr.addr == 0) {
00752       /* { for_us == 0 and netif->ip_addr.addr == 0 } */
00753       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
00754     /* request was not directed to us */
00755     } else {
00756       /* { for_us == 0 and netif->ip_addr.addr != 0 } */
00757       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
00758     }
00759     break;
00760   case ARP_REPLY:
00761     /* ARP reply. We already updated the ARP cache earlier. */
00762     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
00763 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
00764     /* DHCP wants to know about ARP replies from any host with an
00765      * IP address also offered to us by the DHCP server. We do not
00766      * want to take a duplicate IP address on a single network.
00767      * @todo How should we handle redundant (fail-over) interfaces? */
00768     dhcp_arp_reply(netif, &sipaddr);
00769 #endif
00770     break;
00771   default:
00772     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
00773     ETHARP_STATS_INC(etharp.err);
00774     break;
00775   }
00776   /* free ARP packet */
00777   pbuf_free(p);
00778 }
00779 
00780 /**
00781  * Resolve and fill-in Ethernet address header for outgoing IP packet.
00782  *
00783  * For IP multicast and broadcast, corresponding Ethernet addresses
00784  * are selected and the packet is transmitted on the link.
00785  *
00786  * For unicast addresses, the packet is submitted to etharp_query(). In
00787  * case the IP address is outside the local network, the IP address of
00788  * the gateway is used.
00789  *
00790  * @param netif The lwIP network interface which the IP packet will be sent on.
00791  * @param q The pbuf(s) containing the IP packet to be sent.
00792  * @param ipaddr The IP address of the packet destination.
00793  *
00794  * @return
00795  * - ERR_RTE No route to destination (no gateway to external networks),
00796  * or the return type of either etharp_query() or etharp_send_ip().
00797  */
00798 err_t
00799 etharp_output(struct netif *netif, struct pbuf *q, struct ip_addr *ipaddr)
00800 {
00801   struct eth_addr *dest, mcastaddr;
00802 
00803   /* make room for Ethernet header - should not fail */
00804   if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
00805     /* bail out */
00806     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n"));
00807     LINK_STATS_INC(link.lenerr);
00808     return ERR_BUF;
00809   }
00810 
00811   /* assume unresolved Ethernet address */
00812   dest = NULL;
00813   /* Determine on destination hardware address. Broadcasts and multicasts
00814    * are special, other IP addresses are looked up in the ARP table. */
00815 
00816   /* broadcast destination IP address? */
00817   if (ip_addr_isbroadcast(ipaddr, netif)) {
00818     /* broadcast on Ethernet also */
00819     dest = (struct eth_addr *)&ethbroadcast;
00820   /* multicast destination IP address? */
00821   } else if (ip_addr_ismulticast(ipaddr)) {
00822     /* Hash IP multicast address to MAC address.*/
00823     mcastaddr.addr[0] = 0x01;
00824     mcastaddr.addr[1] = 0x00;
00825     mcastaddr.addr[2] = 0x5e;
00826     mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
00827     mcastaddr.addr[4] = ip4_addr3(ipaddr);
00828     mcastaddr.addr[5] = ip4_addr4(ipaddr);
00829     /* destination Ethernet address is multicast */
00830     dest = &mcastaddr;
00831   /* unicast destination IP address? */
00832   } else {
00833     /* outside local network? */
00834     if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) {
00835       /* interface has default gateway? */
00836       if (netif->gw.addr != 0) {
00837         /* send to hardware address of default gateway IP address */
00838         ipaddr = &(netif->gw);
00839       /* no default gateway available */
00840       } else {
00841         /* no route to destination error (default gateway missing) */
00842         return ERR_RTE;
00843       }
00844     }
00845     /* queue on destination Ethernet address belonging to ipaddr */
00846     return etharp_query(netif, ipaddr, q);
00847   }
00848 
00849   /* continuation for multicast/broadcast destinations */
00850   /* obtain source Ethernet address of the given interface */
00851   /* send packet directly on the link */
00852   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
00853 }
00854 
00855 /**
00856  * Send an ARP request for the given IP address and/or queue a packet.
00857  *
00858  * If the IP address was not yet in the cache, a pending ARP cache entry
00859  * is added and an ARP request is sent for the given address. The packet
00860  * is queued on this entry.
00861  *
00862  * If the IP address was already pending in the cache, a new ARP request
00863  * is sent for the given address. The packet is queued on this entry.
00864  *
00865  * If the IP address was already stable in the cache, and a packet is
00866  * given, it is directly sent and no ARP request is sent out. 
00867  * 
00868  * If the IP address was already stable in the cache, and no packet is
00869  * given, an ARP request is sent out.
00870  * 
00871  * @param netif The lwIP network interface on which ipaddr
00872  * must be queried for.
00873  * @param ipaddr The IP address to be resolved.
00874  * @param q If non-NULL, a pbuf that must be delivered to the IP address.
00875  * q is not freed by this function.
00876  *
00877  * @note q must only be ONE packet, not a packet queue!
00878  *
00879  * @return
00880  * - ERR_BUF Could not make room for Ethernet header.
00881  * - ERR_MEM Hardware address unknown, and no more ARP entries available
00882  *   to query for address or queue the packet.
00883  * - ERR_MEM Could not queue packet due to memory shortage.
00884  * - ERR_RTE No route to destination (no gateway to external networks).
00885  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00886  *
00887  */
00888 err_t
00889 etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
00890 {
00891   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
00892   err_t result = ERR_MEM;
00893   s8_t i; /* ARP entry index */
00894 
00895   /* non-unicast address? */
00896   if (ip_addr_isbroadcast(ipaddr, netif) ||
00897       ip_addr_ismulticast(ipaddr) ||
00898       ip_addr_isany(ipaddr)) {
00899     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
00900     return ERR_ARG;
00901   }
00902 
00903   /* find entry in ARP cache, ask to create entry if queueing packet */
00904 #if LWIP_NETIF_HWADDRHINT
00905   i = find_entry(ipaddr, ETHARP_TRY_HARD, netif);
00906 #else /* LWIP_NETIF_HWADDRHINT */
00907   i = find_entry(ipaddr, ETHARP_TRY_HARD);
00908 #endif /* LWIP_NETIF_HWADDRHINT */
00909 
00910   /* could not find or create entry? */
00911   if (i < 0) {
00912     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
00913     if (q) {
00914       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
00915       ETHARP_STATS_INC(etharp.memerr);
00916     }
00917     return (err_t)i;
00918   }
00919 
00920   /* mark a fresh entry as pending (we just sent a request) */
00921   if (arp_table[i].state == ETHARP_STATE_EMPTY) {
00922     arp_table[i].state = ETHARP_STATE_PENDING;
00923   }
00924 
00925   /* { i is either a STABLE or (new or existing) PENDING entry } */
00926   LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
00927   ((arp_table[i].state == ETHARP_STATE_PENDING) ||
00928    (arp_table[i].state == ETHARP_STATE_STABLE)));
00929 
00930   /* do we have a pending entry? or an implicit query request? */
00931   if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
00932     /* try to resolve it; send out ARP request */
00933     result = etharp_request(netif, ipaddr);
00934     if (result != ERR_OK) {
00935       /* ARP request couldn't be sent */
00936       /* We don't re-send arp request in etharp_tmr, but we still queue packets,
00937          since this failure could be temporary, and the next packet calling
00938          etharp_query again could lead to sending the queued packets. */
00939     }
00940   }
00941   
00942   /* packet given? */
00943   if (q != NULL) {
00944     /* stable entry? */
00945     if (arp_table[i].state == ETHARP_STATE_STABLE) {
00946       /* we have a valid IP->Ethernet address mapping */
00947       /* send the packet */
00948       result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
00949     /* pending entry? (either just created or already pending */
00950     } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
00951 #if ARP_QUEUEING /* queue the given q packet */
00952       struct pbuf *p;
00953       int copy_needed = 0;
00954       /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
00955        * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
00956        * PBUF_ROMs can be left as they are, since ROM must not get changed. */
00957       p = q;
00958       while (p) {
00959         LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
00960         if(p->type != PBUF_ROM) {
00961           copy_needed = 1;
00962           break;
00963         }
00964         p = p->next;
00965       }
00966       if(copy_needed) {
00967         /* copy the whole packet into new pbufs */
00968         p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
00969         if(p != NULL) {
00970           if (pbuf_copy(p, q) != ERR_OK) {
00971             pbuf_free(p);
00972             p = NULL;
00973           }
00974         }
00975       } else {
00976         /* referencing the old pbuf is enough */
00977         p = q;
00978         pbuf_ref(p);
00979       }
00980       /* packet could be taken over? */
00981       if (p != NULL) {
00982         /* queue packet ... */
00983         struct etharp_q_entry *new_entry;
00984         /* allocate a new arp queue entry */
00985         new_entry = memp_malloc(MEMP_ARP_QUEUE);
00986         if (new_entry != NULL) {
00987           new_entry->next = 0;
00988           new_entry->p = p;
00989           if(arp_table[i].q != NULL) {
00990             /* queue was already existent, append the new entry to the end */
00991             struct etharp_q_entry *r;
00992             r = arp_table[i].q;
00993             while (r->next != NULL) {
00994               r = r->next;
00995             }
00996             r->next = new_entry;
00997           } else {
00998             /* queue did not exist, first item in queue */
00999             arp_table[i].q = new_entry;
01000           }
01001           LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01002           result = ERR_OK;
01003         } else {
01004           /* the pool MEMP_ARP_QUEUE is empty */
01005           pbuf_free(p);
01006           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));
01007           /* { result == ERR_MEM } through initialization */
01008         }
01009       } else {
01010         ETHARP_STATS_INC(etharp.memerr);
01011         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));
01012         /* { result == ERR_MEM } through initialization */
01013       }
01014 #else /* ARP_QUEUEING == 0 */
01015       /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
01016       /* { result == ERR_MEM } through initialization */
01017       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
01018 #endif
01019     }
01020   }
01021   return result;
01022 }
01023 
01024 /**
01025  * Send a raw ARP packet (opcode and all addresses can be modified)
01026  *
01027  * @param netif the lwip network interface on which to send the ARP packet
01028  * @param ethsrc_addr the source MAC address for the ethernet header
01029  * @param ethdst_addr the destination MAC address for the ethernet header
01030  * @param hwsrc_addr the source MAC address for the ARP protocol header
01031  * @param ipsrc_addr the source IP address for the ARP protocol header
01032  * @param hwdst_addr the destination MAC address for the ARP protocol header
01033  * @param ipdst_addr the destination IP address for the ARP protocol header
01034  * @param opcode the type of the ARP packet
01035  * @return ERR_OK if the ARP packet has been sent
01036  *         ERR_MEM if the ARP packet couldn't be allocated
01037  *         any other err_t on failure
01038  */
01039 #if !LWIP_AUTOIP
01040 static
01041 #endif /* LWIP_AUTOIP */
01042 err_t
01043 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
01044            const struct eth_addr *ethdst_addr,
01045            const struct eth_addr *hwsrc_addr, const struct ip_addr *ipsrc_addr,
01046            const struct eth_addr *hwdst_addr, const struct ip_addr *ipdst_addr,
01047            const u16_t opcode)
01048 {
01049   struct pbuf *p;
01050   err_t result = ERR_OK;
01051   u8_t k; /* ARP entry index */
01052   struct eth_hdr *ethhdr;
01053   struct etharp_hdr *hdr;
01054 #if LWIP_AUTOIP
01055   const u8_t * ethdst_hwaddr;
01056 #endif /* LWIP_AUTOIP */
01057 
01058   /* allocate a pbuf for the outgoing ARP request packet */
01059   p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
01060   /* could allocate a pbuf for an ARP request? */
01061   if (p == NULL) {
01062     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | 2, ("etharp_raw: could not allocate pbuf for ARP request.\n"));
01063     ETHARP_STATS_INC(etharp.memerr);
01064     return ERR_MEM;
01065   }
01066   LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
01067               (p->len >= SIZEOF_ETHARP_PACKET));
01068 
01069   ethhdr = (struct eth_hdr *)p->payload;
01070   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
01071   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
01072   hdr->opcode = htons(opcode);
01073 
01074   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
01075               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
01076   k = ETHARP_HWADDR_LEN;
01077 #if LWIP_AUTOIP
01078   /* If we are using Link-Local, ARP packets must be broadcast on the
01079    * link layer. (See RFC3927 Section 2.5) */
01080   ethdst_hwaddr = ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
01081 #endif /* LWIP_AUTOIP */
01082   /* Write MAC-Addresses (combined loop for both headers) */
01083   while(k > 0) {
01084     k--;
01085     /* Write the ARP MAC-Addresses */
01086     hdr->shwaddr.addr[k] = hwsrc_addr->addr[k];
01087     hdr->dhwaddr.addr[k] = hwdst_addr->addr[k];
01088     /* Write the Ethernet MAC-Addresses */
01089 #if LWIP_AUTOIP
01090     ethhdr->dest.addr[k] = ethdst_hwaddr[k];
01091 #else  /* LWIP_AUTOIP */
01092     ethhdr->dest.addr[k] = ethdst_addr->addr[k];
01093 #endif /* LWIP_AUTOIP */
01094     ethhdr->src.addr[k]  = ethsrc_addr->addr[k];
01095   }
01096   hdr->sipaddr = *(struct ip_addr2 *)ipsrc_addr;
01097   hdr->dipaddr = *(struct ip_addr2 *)ipdst_addr;
01098 
01099   hdr->hwtype = htons(HWTYPE_ETHERNET);
01100   hdr->proto = htons(ETHTYPE_IP);
01101   /* set hwlen and protolen together */
01102   hdr->_hwlen_protolen = htons((ETHARP_HWADDR_LEN << 8) | sizeof(struct ip_addr));
01103 
01104   ethhdr->type = htons(ETHTYPE_ARP);
01105   /* send ARP query */
01106   result = netif->linkoutput(netif, p);
01107   ETHARP_STATS_INC(etharp.xmit);
01108   /* free ARP query packet */
01109   pbuf_free(p);
01110   p = NULL;
01111   /* could not allocate pbuf for ARP request */
01112 
01113   return result;
01114 }
01115 
01116 /**
01117  * Send an ARP request packet asking for ipaddr.
01118  *
01119  * @param netif the lwip network interface on which to send the request
01120  * @param ipaddr the IP address for which to ask
01121  * @return ERR_OK if the request has been sent
01122  *         ERR_MEM if the ARP packet couldn't be allocated
01123  *         any other err_t on failure
01124  */
01125 err_t
01126 etharp_request(struct netif *netif, struct ip_addr *ipaddr)
01127 {
01128   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
01129   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
01130                     (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
01131                     ipaddr, ARP_REQUEST);
01132 }
01133 
01134 /**
01135  * Process received ethernet frames. Using this function instead of directly
01136  * calling ip_input and passing ARP frames through etharp in ethernetif_input,
01137  * the ARP cache is protected from concurrent access.
01138  *
01139  * @param p the recevied packet, p->payload pointing to the ethernet header
01140  * @param netif the network interface on which the packet was received
01141  */
01142 err_t
01143 ethernet_input(struct pbuf *p, struct netif *netif)
01144 {
01145   struct eth_hdr* ethhdr;
01146   u16_t type;
01147 
01148   /* points to packet payload, which starts with an Ethernet header */
01149   ethhdr = (struct eth_hdr *)p->payload;
01150   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
01151     ("ethernet_input: dest:%02x:%02x:%02x:%02x:%02x:%02x, src:%02x:%02x:%02x:%02x:%02x:%02x, type:%2hx\n",
01152      (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
01153      (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
01154      (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
01155      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
01156      (unsigned)htons(ethhdr->type)));
01157 
01158   type = htons(ethhdr->type);
01159 #if ETHARP_SUPPORT_VLAN
01160   if (type == ETHTYPE_VLAN) {
01161     struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
01162 #ifdef ETHARP_VLAN_CHECK /* if not, allow all VLANs */
01163     if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
01164       /* silently ignore this packet: not for our VLAN */
01165       pbuf_free(p);
01166       return ERR_OK;
01167     }
01168 #endif /* ETHARP_VLAN_CHECK */
01169     type = htons(vlan->tpid);
01170   }
01171 #endif /* ETHARP_SUPPORT_VLAN */
01172 
01173   switch (type) {
01174     /* IP packet? */
01175     case ETHTYPE_IP:
01176 #if ETHARP_TRUST_IP_MAC
01177       /* update ARP table */
01178       etharp_ip_input(netif, p);
01179 #endif /* ETHARP_TRUST_IP_MAC */
01180       /* skip Ethernet header */
01181       if(pbuf_header(p, -(s16_t)SIZEOF_ETH_HDR)) {
01182         LWIP_ASSERT("Can't move over header in packet", 0);
01183         pbuf_free(p);
01184         p = NULL;
01185       } else {
01186         /* pass to IP layer */
01187         ip_input(p, netif);
01188       }
01189       break;
01190       
01191     case ETHTYPE_ARP:
01192       /* pass p to ARP module */
01193       etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
01194       break;
01195 
01196 #if PPPOE_SUPPORT
01197     case ETHTYPE_PPPOEDISC: /* PPP Over Ethernet Discovery Stage */
01198       pppoe_disc_input(netif, p);
01199       break;
01200 
01201     case ETHTYPE_PPPOE: /* PPP Over Ethernet Session Stage */
01202       pppoe_data_input(netif, p);
01203       break;
01204 #endif /* PPPOE_SUPPORT */
01205 
01206     default:
01207       ETHARP_STATS_INC(etharp.proterr);
01208       ETHARP_STATS_INC(etharp.drop);
01209       pbuf_free(p);
01210       p = NULL;
01211       break;
01212   }
01213 
01214   /* This means the pbuf is freed or consumed,
01215      so the caller doesn't have to free it again */
01216   return ERR_OK;
01217 }
01218 #endif /* LWIP_ARP */