etharp.c

00001 /**
00002  * @file
00003  * Address Resolution Protocol module for IP over Ethernet
00004  *
00005  * Functionally, ARP is divided into two parts. The first maps an IP address
00006  * to a physical address when sending a packet, and the second part answers
00007  * requests from other machines for our physical address.
00008  *
00009  * This implementation complies with RFC 826 (Ethernet ARP). It supports
00010  * Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6
00011  * if an interface calls etharp_gratuitous(our_netif) upon address change.
00012  */
00013 
00014 /*
00015  * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
00016  * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv>
00017  * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands.
00018  * All rights reserved.
00019  *
00020  * Redistribution and use in source and binary forms, with or without modification,
00021  * are permitted provided that the following conditions are met:
00022  *
00023  * 1. Redistributions of source code must retain the above copyright notice,
00024  *    this list of conditions and the following disclaimer.
00025  * 2. Redistributions in binary form must reproduce the above copyright notice,
00026  *    this list of conditions and the following disclaimer in the documentation
00027  *    and/or other materials provided with the distribution.
00028  * 3. The name of the author may not be used to endorse or promote products
00029  *    derived from this software without specific prior written permission.
00030  *
00031  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00032  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00033  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00034  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00035  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00036  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00037  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00038  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00039  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00040  * OF SUCH DAMAGE.
00041  *
00042  * This file is part of the lwIP TCP/IP stack.
00043  *
00044  */
00045  
00046 #include "lwip/opt.h"
00047 
00048 #if LWIP_ARP || LWIP_ETHERNET
00049 
00050 #include "lwip/ip_addr.h"
00051 #include "lwip/def.h"
00052 #include "lwip/ip.h"
00053 #include "lwip/stats.h"
00054 #include "lwip/snmp.h"
00055 #include "lwip/dhcp.h "
00056 #include "lwip/autoip.h"
00057 #include "netif/etharp.h"
00058 
00059 #if PPPOE_SUPPORT
00060 #include "netif/ppp_oe.h"
00061 #endif /* PPPOE_SUPPORT */
00062 
00063 #include <string.h>
00064 
00065 const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}};
00066 const struct eth_addr ethzero = {{0,0,0,0,0,0}};
00067 
00068 #if LWIP_ARP /* don't build if not configured for use in lwipopts.h */
00069 
00070 /** the time an ARP entry stays valid after its last update,
00071  *  for ARP_TMR_INTERVAL = 5000, this is
00072  *  (240 * 5) seconds = 20 minutes.
00073  */
00074 #define ARP_MAXAGE 240
00075 /** the time an ARP entry stays pending after first request,
00076  *  for ARP_TMR_INTERVAL = 5000, this is
00077  *  (2 * 5) seconds = 10 seconds.
00078  * 
00079  *  @internal Keep this number at least 2, otherwise it might
00080  *  run out instantly if the timeout occurs directly after a request.
00081  */
00082 #define ARP_MAXPENDING 2
00083 
00084 #define HWTYPE_ETHERNET 1
00085 
00086 enum etharp_state {
00087   ETHARP_STATE_EMPTY = 0,
00088   ETHARP_STATE_PENDING,
00089   ETHARP_STATE_STABLE
00090 };
00091 
00092 struct etharp_entry {
00093 #if ARP_QUEUEING
00094   /** Pointer to queue of pending outgoing packets on this ARP entry. */
00095   struct etharp_q_entry *q;
00096 #endif /* ARP_QUEUEING */
00097   ip_addr_t ipaddr;
00098   struct eth_addr ethaddr;
00099 #if LWIP_SNMP
00100   struct netif *netif;
00101 #endif /* LWIP_SNMP */
00102   u8_t state;
00103   u8_t ctime;
00104 #if ETHARP_SUPPORT_STATIC_ENTRIES
00105   u8_t static_entry;
00106 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00107 };
00108 
00109 static struct etharp_entry arp_table[ARP_TABLE_SIZE];
00110 
00111 #if !LWIP_NETIF_HWADDRHINT
00112 static u8_t etharp_cached_entry;
00113 #endif /* !LWIP_NETIF_HWADDRHINT */
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_FLAG_TRY_HARD     1
00118 #define ETHARP_FLAG_FIND_ONLY    2
00119 #define ETHARP_FLAG_STATIC_ENTRY 4
00120 
00121 #if LWIP_NETIF_HWADDRHINT
00122 #define ETHARP_SET_HINT(netif, hint)  if (((netif) != NULL) && ((netif)->addr_hint != NULL))  \
00123                                       *((netif)->addr_hint) = (hint);
00124 #else /* LWIP_NETIF_HWADDRHINT */
00125 #define ETHARP_SET_HINT(netif, hint)  (etharp_cached_entry = (hint))
00126 #endif /* LWIP_NETIF_HWADDRHINT */
00127 
00128 static err_t update_arp_entry(struct netif *netif, ip_addr_t *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 "ARP_TABLE_SIZE must fit in an s8_t, 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 /* ARP_QUEUEING */
00158 
00159 /** Clean up ARP table entries */
00160 static void
00161 free_entry(int i)
00162 {
00163   /* remove from SNMP ARP index tree */
00164   snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
00165 #if ARP_QUEUEING
00166   /* and empty packet queue */
00167   if (arp_table[i].q != NULL) {
00168     /* remove all queued packets */
00169     LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
00170     free_etharp_q(arp_table[i].q);
00171     arp_table[i].q = NULL;
00172   }
00173 #endif /* ARP_QUEUEING */
00174   /* recycle entry for re-use */      
00175   arp_table[i].state = ETHARP_STATE_EMPTY;
00176 #if ETHARP_SUPPORT_STATIC_ENTRIES
00177   arp_table[i].static_entry = 0;
00178 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00179 #ifdef LWIP_DEBUG
00180   /* for debugging, clean out the complete entry */
00181   arp_table[i].ctime = 0;
00182 #if LWIP_SNMP
00183   arp_table[i].netif = NULL;
00184 #endif /* LWIP_SNMP */
00185   ip_addr_set_zero(&arp_table[i].ipaddr);
00186   arp_table[i].ethaddr = ethzero;
00187 #endif /* LWIP_DEBUG */
00188 }
00189 
00190 /**
00191  * Clears expired entries in the ARP table.
00192  *
00193  * This function should be called every ETHARP_TMR_INTERVAL milliseconds (5 seconds),
00194  * in order to expire entries in the ARP table.
00195  */
00196 void
00197 etharp_tmr(void)
00198 {
00199   u8_t i;
00200 
00201   LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
00202   /* remove expired entries from the ARP table */
00203   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00204     u8_t state = arp_table[i].state;
00205     if (state != ETHARP_STATE_EMPTY
00206 #if ETHARP_SUPPORT_STATIC_ENTRIES
00207       && (arp_table[i].static_entry == 0)
00208 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00209       ) {
00210       arp_table[i].ctime++;
00211       if ((arp_table[i].ctime >= ARP_MAXAGE) ||
00212           ((arp_table[i].state == ETHARP_STATE_PENDING)  &&
00213            (arp_table[i].ctime >= ARP_MAXPENDING))) {
00214         /* pending or stable entry has become old! */
00215         LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
00216              arp_table[i].state == ETHARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
00217         /* clean up entries that have just been expired */
00218         free_entry(i);
00219       }
00220 #if ARP_QUEUEING
00221       /* still pending entry? (not expired) */
00222       if (arp_table[i].state == ETHARP_STATE_PENDING) {
00223         /* resend an ARP query here? */
00224       }
00225 #endif /* ARP_QUEUEING */
00226     }
00227   }
00228 }
00229 
00230 /**
00231  * Search the ARP table for a matching or new entry.
00232  * 
00233  * If an IP address is given, return a pending or stable ARP entry that matches
00234  * the address. If no match is found, create a new entry with this address set,
00235  * but in state ETHARP_EMPTY. The caller must check and possibly change the
00236  * state of the returned entry.
00237  * 
00238  * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
00239  * 
00240  * In all cases, attempt to create new entries from an empty entry. If no
00241  * empty entries are available and ETHARP_FLAG_TRY_HARD flag is set, recycle
00242  * old entries. Heuristic choose the least important entry for recycling.
00243  *
00244  * @param ipaddr IP address to find in ARP cache, or to add if not found.
00245  * @param flags @see definition of ETHARP_FLAG_*
00246  * @param netif netif related to this address (used for NETIF_HWADDRHINT)
00247  *  
00248  * @return The ARP entry index that matched or is created, ERR_MEM if no
00249  * entry is found or could be recycled.
00250  */
00251 static s8_t
00252 find_entry(ip_addr_t *ipaddr, u8_t flags)
00253 {
00254   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
00255   s8_t empty = ARP_TABLE_SIZE;
00256   u8_t i = 0, age_pending = 0, age_stable = 0;
00257 #if ARP_QUEUEING
00258   /* oldest entry with packets on queue */
00259   s8_t old_queue = ARP_TABLE_SIZE;
00260   /* its age */
00261   u8_t age_queue = 0;
00262 #endif /* ARP_QUEUEING */
00263 
00264   /**
00265    * a) do a search through the cache, remember candidates
00266    * b) select candidate entry
00267    * c) create new entry
00268    */
00269 
00270   /* a) in a single search sweep, do all of this
00271    * 1) remember the first empty entry (if any)
00272    * 2) remember the oldest stable entry (if any)
00273    * 3) remember the oldest pending entry without queued packets (if any)
00274    * 4) remember the oldest pending entry with queued packets (if any)
00275    * 5) search for a matching IP entry, either pending or stable
00276    *    until 5 matches, or all entries are searched for.
00277    */
00278 
00279   for (i = 0; i < ARP_TABLE_SIZE; ++i) {
00280     u8_t state = arp_table[i].state;
00281     /* no empty entry found yet and now we do find one? */
00282     if ((empty == ARP_TABLE_SIZE) && (state == ETHARP_STATE_EMPTY)) {
00283       LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
00284       /* remember first empty entry */
00285       empty = i;
00286     } else if (state != ETHARP_STATE_EMPTY) {
00287       LWIP_ASSERT("state == ETHARP_STATE_PENDING || state == ETHARP_STATE_STABLE",
00288         state == ETHARP_STATE_PENDING || state == ETHARP_STATE_STABLE);
00289       /* if given, does IP address match IP address in ARP entry? */
00290       if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
00291         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching entry %"U16_F"\n", (u16_t)i));
00292         /* found exact IP address match, simply bail out */
00293         return i;
00294       }
00295       /* pending entry? */
00296       if (state == ETHARP_STATE_PENDING) {
00297         /* pending with queued packets? */
00298 #if ARP_QUEUEING
00299         if (arp_table[i].q != NULL) {
00300           if (arp_table[i].ctime >= age_queue) {
00301             old_queue = i;
00302             age_queue = arp_table[i].ctime;
00303           }
00304         } else
00305 #endif /* ARP_QUEUEING */
00306         /* pending without queued packets? */
00307         {
00308           if (arp_table[i].ctime >= age_pending) {
00309             old_pending = i;
00310             age_pending = arp_table[i].ctime;
00311           }
00312         }
00313       /* stable entry? */
00314       } else if (state == ETHARP_STATE_STABLE) {
00315 #if ETHARP_SUPPORT_STATIC_ENTRIES
00316         /* don't record old_stable for static entries since they never expire */
00317         if (arp_table[i].static_entry == 0)
00318 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00319         {
00320           /* remember entry with oldest stable entry in oldest, its age in maxtime */
00321           if (arp_table[i].ctime >= age_stable) {
00322             old_stable = i;
00323             age_stable = arp_table[i].ctime;
00324           }
00325         }
00326       }
00327     }
00328   }
00329   /* { we have no match } => try to create a new entry */
00330    
00331   /* don't create new entry, only search? */
00332   if (((flags & ETHARP_FLAG_FIND_ONLY) != 0) ||
00333       /* or no empty entry found and not allowed to recycle? */
00334       ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_FLAG_TRY_HARD) == 0))) {
00335     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
00336     return (s8_t)ERR_MEM;
00337   }
00338   
00339   /* b) choose the least destructive entry to recycle:
00340    * 1) empty entry
00341    * 2) oldest stable entry
00342    * 3) oldest pending entry without queued packets
00343    * 4) oldest pending entry with queued packets
00344    * 
00345    * { ETHARP_FLAG_TRY_HARD is set at this point }
00346    */ 
00347 
00348   /* 1) empty entry available? */
00349   if (empty < ARP_TABLE_SIZE) {
00350     i = empty;
00351     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
00352   } else {
00353     /* 2) found recyclable stable entry? */
00354     if (old_stable < ARP_TABLE_SIZE) {
00355       /* recycle oldest stable*/
00356       i = old_stable;
00357       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
00358 #if ARP_QUEUEING
00359       /* no queued packets should exist on stable entries */
00360       LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
00361 #endif /* ARP_QUEUEING */
00362     /* 3) found recyclable pending entry without queued packets? */
00363     } else if (old_pending < ARP_TABLE_SIZE) {
00364       /* recycle oldest pending */
00365       i = old_pending;
00366       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
00367 #if ARP_QUEUEING
00368     /* 4) found recyclable pending entry with queued packets? */
00369     } else if (old_queue < ARP_TABLE_SIZE) {
00370       /* recycle oldest pending (queued packets are free in free_entry) */
00371       i = old_queue;
00372       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)));
00373 #endif /* ARP_QUEUEING */
00374       /* no empty or recyclable entries found */
00375     } else {
00376       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty or recyclable entries found\n"));
00377       return (s8_t)ERR_MEM;
00378     }
00379 
00380     /* { empty or recyclable entry found } */
00381     LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00382     free_entry(i);
00383   }
00384 
00385   LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
00386   LWIP_ASSERT("arp_table[i].state == ETHARP_STATE_EMPTY",
00387     arp_table[i].state == ETHARP_STATE_EMPTY);
00388 
00389   /* IP address given? */
00390   if (ipaddr != NULL) {
00391     /* set IP address */
00392     ip_addr_copy(arp_table[i].ipaddr, *ipaddr);
00393   }
00394   arp_table[i].ctime = 0;
00395 #if ETHARP_SUPPORT_STATIC_ENTRIES
00396   arp_table[i].static_entry = 0;
00397 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00398   return (err_t)i;
00399 }
00400 
00401 /**
00402  * Send an IP packet on the network using netif->linkoutput
00403  * The ethernet header is filled in before sending.
00404  *
00405  * @params netif the lwIP network interface on which to send the packet
00406  * @params p the packet to send, p->payload pointing to the (uninitialized) ethernet header
00407  * @params src the source MAC address to be copied into the ethernet header
00408  * @params dst the destination MAC address to be copied into the ethernet header
00409  * @return ERR_OK if the packet was sent, any other err_t on failure
00410  */
00411 static err_t
00412 etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct eth_addr *dst)
00413 {
00414   struct eth_hdr *ethhdr = (struct eth_hdr *)p->payload;
00415 
00416   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00417               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00418   ETHADDR32_COPY(&ethhdr->dest, dst);
00419   ETHADDR16_COPY(&ethhdr->src, src);
00420   ethhdr->type = PP_HTONS(ETHTYPE_IP);
00421   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
00422   /* send the packet */
00423   return netif->linkoutput(netif, p);
00424 }
00425 
00426 /**
00427  * Update (or insert) a IP/MAC address pair in the ARP cache.
00428  *
00429  * If a pending entry is resolved, any queued packets will be sent
00430  * at this point.
00431  * 
00432  * @param netif netif related to this entry (used for NETIF_ADDRHINT)
00433  * @param ipaddr IP address of the inserted ARP entry.
00434  * @param ethaddr Ethernet address of the inserted ARP entry.
00435  * @param flags @see definition of ETHARP_FLAG_*
00436  *
00437  * @return
00438  * - ERR_OK Succesfully updated ARP cache.
00439  * - ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set.
00440  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00441  *
00442  * @see pbuf_free()
00443  */
00444 static err_t
00445 update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
00446 {
00447   s8_t i;
00448   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
00449   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",
00450     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00451     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00452     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00453   /* non-unicast address? */
00454   if (ip_addr_isany(ipaddr) ||
00455       ip_addr_isbroadcast(ipaddr, netif) ||
00456       ip_addr_ismulticast(ipaddr)) {
00457     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
00458     return ERR_ARG;
00459   }
00460   /* find or create ARP entry */
00461   i = find_entry(ipaddr, flags);
00462   /* bail out if no entry could be found */
00463   if (i < 0) {
00464     return (err_t)i;
00465   }
00466 
00467 #if ETHARP_SUPPORT_STATIC_ENTRIES
00468   if (flags & ETHARP_FLAG_STATIC_ENTRY) {
00469     /* record static type */
00470     arp_table[i].static_entry = 1;
00471   }
00472 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00473 
00474   /* mark it stable */
00475   arp_table[i].state = ETHARP_STATE_STABLE;
00476 
00477 #if LWIP_SNMP
00478   /* record network interface */
00479   arp_table[i].netif = netif;
00480 #endif /* LWIP_SNMP */
00481   /* insert in SNMP ARP index tree */
00482   snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
00483 
00484   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
00485   /* update address */
00486   ETHADDR32_COPY(&arp_table[i].ethaddr, ethaddr);
00487   /* reset time stamp */
00488   arp_table[i].ctime = 0;
00489 #if ARP_QUEUEING
00490   /* this is where we will send out queued packets! */
00491   while (arp_table[i].q != NULL) {
00492     struct pbuf *p;
00493     /* remember remainder of queue */
00494     struct etharp_q_entry *q = arp_table[i].q;
00495     /* pop first item off the queue */
00496     arp_table[i].q = q->next;
00497     /* get the packet pointer */
00498     p = q->p;
00499     /* now queue entry can be freed */
00500     memp_free(MEMP_ARP_QUEUE, q);
00501     /* send the queued IP packet */
00502     etharp_send_ip(netif, p, (struct eth_addr*)(netif->hwaddr), ethaddr);
00503     /* free the queued IP packet */
00504     pbuf_free(p);
00505   }
00506 #endif /* ARP_QUEUEING */
00507   return ERR_OK;
00508 }
00509 
00510 #if ETHARP_SUPPORT_STATIC_ENTRIES
00511 /** Add a new static entry to the ARP table. If an entry exists for the
00512  * specified IP address, this entry is overwritten.
00513  * If packets are queued for the specified IP address, they are sent out.
00514  *
00515  * @param ipaddr IP address for the new static entry
00516  * @param ethaddr ethernet address for the new static entry
00517  * @return @see return values of etharp_add_static_entry
00518  */
00519 err_t
00520 etharp_add_static_entry(ip_addr_t *ipaddr, struct eth_addr *ethaddr)
00521 {
00522   struct netif *netif;
00523   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_add_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n",
00524     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr),
00525     ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
00526     ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
00527 
00528   netif = ip_route(ipaddr);
00529   if (netif == NULL) {
00530     return ERR_RTE;
00531   }
00532 
00533   return update_arp_entry(netif, ipaddr, ethaddr, ETHARP_FLAG_TRY_HARD | ETHARP_FLAG_STATIC_ENTRY);
00534 }
00535 
00536 /** Remove a static entry from the ARP table previously added with a call to
00537  * etharp_add_static_entry.
00538  *
00539  * @param ipaddr IP address of the static entry to remove
00540  * @return ERR_OK: entry removed
00541  *         ERR_MEM: entry wasn't found
00542  *         ERR_ARG: entry wasn't a static entry but a dynamic one
00543  */
00544 err_t
00545 etharp_remove_static_entry(ip_addr_t *ipaddr)
00546 {
00547   s8_t i;
00548   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00549     ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
00550 
00551   /* find or create ARP entry */
00552   i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
00553   /* bail out if no entry could be found */
00554   if (i < 0) {
00555     return (err_t)i;
00556   }
00557 
00558   if ((arp_table[i].state != ETHARP_STATE_STABLE) ||
00559     (arp_table[i].static_entry == 0)) {
00560     /* entry wasn't a static entry, cannot remove it */
00561     return ERR_ARG;
00562   }
00563   /* entry found, free it */
00564   free_entry(i);
00565   return ERR_OK;
00566 }
00567 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
00568 
00569 /**
00570  * Finds (stable) ethernet/IP address pair from ARP table
00571  * using interface and IP address index.
00572  * @note the addresses in the ARP table are in network order!
00573  *
00574  * @param netif points to interface index
00575  * @param ipaddr points to the (network order) IP address index
00576  * @param eth_ret points to return pointer
00577  * @param ip_ret points to return pointer
00578  * @return table index if found, -1 otherwise
00579  */
00580 s8_t
00581 etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
00582          struct eth_addr **eth_ret, ip_addr_t **ip_ret)
00583 {
00584   s8_t i;
00585 
00586   LWIP_ASSERT("eth_ret != NULL && ip_ret != NULL",
00587     eth_ret != NULL && ip_ret != NULL);
00588 
00589   LWIP_UNUSED_ARG(netif);
00590 
00591   i = find_entry(ipaddr, ETHARP_FLAG_FIND_ONLY);
00592   if((i >= 0) && arp_table[i].state == ETHARP_STATE_STABLE) {
00593       *eth_ret = &arp_table[i].ethaddr;
00594       *ip_ret = &arp_table[i].ipaddr;
00595       return i;
00596   }
00597   return -1;
00598 }
00599 
00600 #if ETHARP_TRUST_IP_MAC
00601 /**
00602  * Updates the ARP table using the given IP packet.
00603  *
00604  * Uses the incoming IP packet's source address to update the
00605  * ARP cache for the local network. The function does not alter
00606  * or free the packet. This function must be called before the
00607  * packet p is passed to the IP layer.
00608  *
00609  * @param netif The lwIP network interface on which the IP packet pbuf arrived.
00610  * @param p The IP packet that arrived on netif.
00611  *
00612  * @return NULL
00613  *
00614  * @see pbuf_free()
00615  */
00616 static void
00617 etharp_ip_input(struct netif *netif, struct pbuf *p)
00618 {
00619   struct eth_hdr *ethhdr;
00620   struct ip_hdr *iphdr;
00621   ip_addr_t iphdr_src;
00622   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00623 
00624   /* Only insert an entry if the source IP address of the
00625      incoming IP packet comes from a host on the local network. */
00626   ethhdr = (struct eth_hdr *)p->payload;
00627   iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00628 #if ETHARP_SUPPORT_VLAN
00629   if (ethhdr->type == ETHTYPE_VLAN) {
00630     iphdr = (struct ip_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00631   }
00632 #endif /* ETHARP_SUPPORT_VLAN */
00633 
00634   ip_addr_copy(iphdr_src, iphdr->src);
00635 
00636   /* source is not on the local network? */
00637   if (!ip_addr_netcmp(&iphdr_src, &(netif->ip_addr), &(netif->netmask))) {
00638     /* do nothing */
00639     return;
00640   }
00641 
00642   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n"));
00643   /* update the source IP address in the cache, if present */
00644   /* @todo We could use ETHARP_FLAG_TRY_HARD if we think we are going to talk
00645    * back soon (for example, if the destination IP address is ours. */
00646   update_arp_entry(netif, &iphdr_src, &(ethhdr->src), ETHARP_FLAG_FIND_ONLY);
00647 }
00648 #endif /* ETHARP_TRUST_IP_MAC */
00649 
00650 /**
00651  * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
00652  * send out queued IP packets. Updates cache with snooped address pairs.
00653  *
00654  * Should be called for incoming ARP packets. The pbuf in the argument
00655  * is freed by this function.
00656  *
00657  * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
00658  * @param ethaddr Ethernet address of netif.
00659  * @param p The ARP packet that arrived on netif. Is freed by this function.
00660  *
00661  * @return NULL
00662  *
00663  * @see pbuf_free()
00664  */
00665 static void
00666 etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
00667 {
00668   struct etharp_hdr *hdr;
00669   struct eth_hdr *ethhdr;
00670   /* these are aligned properly, whereas the ARP header fields might not be */
00671   ip_addr_t sipaddr, dipaddr;
00672   u8_t for_us;
00673 #if LWIP_AUTOIP
00674   const u8_t * ethdst_hwaddr;
00675 #endif /* LWIP_AUTOIP */
00676 
00677   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
00678 
00679   /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
00680      since a struct etharp_hdr is pointed to p->payload, so it musn't be chained! */
00681   if (p->len < SIZEOF_ETHARP_PACKET) {
00682     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00683       ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len,
00684       (s16_t)SIZEOF_ETHARP_PACKET));
00685     ETHARP_STATS_INC(etharp.lenerr);
00686     ETHARP_STATS_INC(etharp.drop);
00687     pbuf_free(p);
00688     return;
00689   }
00690 
00691   ethhdr = (struct eth_hdr *)p->payload;
00692   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
00693 #if ETHARP_SUPPORT_VLAN
00694   if (ethhdr->type == ETHTYPE_VLAN) {
00695     hdr = (struct etharp_hdr *)(((u8_t*)ethhdr) + SIZEOF_ETH_HDR + SIZEOF_VLAN_HDR);
00696   }
00697 #endif /* ETHARP_SUPPORT_VLAN */
00698 
00699   /* RFC 826 "Packet Reception": */
00700   if ((hdr->hwtype != PP_HTONS(HWTYPE_ETHERNET)) ||
00701       (hdr->hwlen != ETHARP_HWADDR_LEN) ||
00702       (hdr->protolen != sizeof(ip_addr_t)) ||
00703       (hdr->proto != PP_HTONS(ETHTYPE_IP)) ||
00704       (ethhdr->type != PP_HTONS(ETHTYPE_ARP)))  {
00705     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
00706       ("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",
00707       hdr->hwtype, hdr->hwlen, hdr->proto, hdr->protolen, ethhdr->type));
00708     ETHARP_STATS_INC(etharp.proterr);
00709     ETHARP_STATS_INC(etharp.drop);
00710     pbuf_free(p);
00711     return;
00712   }
00713   ETHARP_STATS_INC(etharp.recv);
00714 
00715 #if LWIP_AUTOIP
00716   /* We have to check if a host already has configured our random
00717    * created link local address and continously check if there is
00718    * a host with this IP-address so we can detect collisions */
00719   autoip_arp_reply(netif, hdr);
00720 #endif /* LWIP_AUTOIP */
00721 
00722   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00723    * structure packing (not using structure copy which breaks strict-aliasing rules). */
00724   IPADDR2_COPY(&sipaddr, &hdr->sipaddr);
00725   IPADDR2_COPY(&dipaddr, &hdr->dipaddr);
00726 
00727   /* this interface is not configured? */
00728   if (ip_addr_isany(&netif->ip_addr)) {
00729     for_us = 0;
00730   } else {
00731     /* ARP packet directed to us? */
00732     for_us = (u8_t)ip_addr_cmp(&dipaddr, &(netif->ip_addr));
00733   }
00734 
00735   /* ARP message directed to us?
00736       -> add IP address in ARP cache; assume requester wants to talk to us,
00737          can result in directly sending the queued packets for this host.
00738      ARP message not directed to us?
00739       ->  update the source IP address in the cache, if present */
00740   update_arp_entry(netif, &sipaddr, &(hdr->shwaddr),
00741                    for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY);
00742 
00743   /* now act on the message itself */
00744   switch (hdr->opcode) {
00745   /* ARP request? */
00746   case PP_HTONS(ARP_REQUEST):
00747     /* ARP request. If it asked for our address, we send out a
00748      * reply. In any case, we time-stamp any existing ARP entry,
00749      * and possiby send out an IP packet that was queued on it. */
00750 
00751     LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP request\n"));
00752     /* ARP request for our address? */
00753     if (for_us) {
00754 
00755       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n"));
00756       /* Re-use pbuf to send ARP reply.
00757          Since we are re-using an existing pbuf, we can't call etharp_raw since
00758          that would allocate a new pbuf. */
00759       hdr->opcode = htons(ARP_REPLY);
00760 
00761       IPADDR2_COPY(&hdr->dipaddr, &hdr->sipaddr);
00762       IPADDR2_COPY(&hdr->sipaddr, &netif->ip_addr);
00763 
00764       LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
00765                   (netif->hwaddr_len == ETHARP_HWADDR_LEN));
00766 #if LWIP_AUTOIP
00767       /* If we are using Link-Local, all ARP packets that contain a Link-Local
00768        * 'sender IP address' MUST be sent using link-layer broadcast instead of
00769        * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
00770       ethdst_hwaddr = ip_addr_islinklocal(&netif->ip_addr) ? (u8_t*)(ethbroadcast.addr) : hdr->shwaddr.addr;
00771 #endif /* LWIP_AUTOIP */
00772 
00773       ETHADDR16_COPY(&hdr->dhwaddr, &hdr->shwaddr);
00774 #if LWIP_AUTOIP
00775       ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
00776 #else  /* LWIP_AUTOIP */
00777       ETHADDR16_COPY(&ethhdr->dest, &hdr->shwaddr);
00778 #endif /* LWIP_AUTOIP */
00779       ETHADDR16_COPY(&hdr->shwaddr, ethaddr);
00780       ETHADDR16_COPY(&ethhdr->src, ethaddr);
00781 
00782       /* hwtype, hwaddr_len, proto, protolen and the type in the ethernet header
00783          are already correct, we tested that before */
00784 
00785       /* return ARP reply */
00786       netif->linkoutput(netif, p);
00787     /* we are not configured? */
00788     } else if (ip_addr_isany(&netif->ip_addr)) {
00789       /* { for_us == 0 and netif->ip_addr.addr == 0 } */
00790       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n"));
00791     /* request was not directed to us */
00792     } else {
00793       /* { for_us == 0 and netif->ip_addr.addr != 0 } */
00794       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
00795     }
00796     break;
00797   case PP_HTONS(ARP_REPLY):
00798     /* ARP reply. We already updated the ARP cache earlier. */
00799     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
00800 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
00801     /* DHCP wants to know about ARP replies from any host with an
00802      * IP address also offered to us by the DHCP server. We do not
00803      * want to take a duplicate IP address on a single network.
00804      * @todo How should we handle redundant (fail-over) interfaces? */
00805     dhcp_arp_reply(netif, &sipaddr);
00806 #endif /* (LWIP_DHCP && DHCP_DOES_ARP_CHECK) */
00807     break;
00808   default:
00809     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
00810     ETHARP_STATS_INC(etharp.err);
00811     break;
00812   }
00813   /* free ARP packet */
00814   pbuf_free(p);
00815 }
00816 
00817 /**
00818  * Resolve and fill-in Ethernet address header for outgoing IP packet.
00819  *
00820  * For IP multicast and broadcast, corresponding Ethernet addresses
00821  * are selected and the packet is transmitted on the link.
00822  *
00823  * For unicast addresses, the packet is submitted to etharp_query(). In
00824  * case the IP address is outside the local network, the IP address of
00825  * the gateway is used.
00826  *
00827  * @param netif The lwIP network interface which the IP packet will be sent on.
00828  * @param q The pbuf(s) containing the IP packet to be sent.
00829  * @param ipaddr The IP address of the packet destination.
00830  *
00831  * @return
00832  * - ERR_RTE No route to destination (no gateway to external networks),
00833  * or the return type of either etharp_query() or etharp_send_ip().
00834  */
00835 err_t
00836 etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
00837 {
00838   struct eth_addr *dest, mcastaddr;
00839 
00840   /* make room for Ethernet header - should not fail */
00841   if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
00842     /* bail out */
00843     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
00844       ("etharp_output: could not allocate room for header.\n"));
00845     LINK_STATS_INC(link.lenerr);
00846     return ERR_BUF;
00847   }
00848 
00849   /* assume unresolved Ethernet address */
00850   dest = NULL;
00851   /* Determine on destination hardware address. Broadcasts and multicasts
00852    * are special, other IP addresses are looked up in the ARP table. */
00853 
00854   /* broadcast destination IP address? */
00855   if (ip_addr_isbroadcast(ipaddr, netif)) {
00856     /* broadcast on Ethernet also */
00857     dest = (struct eth_addr *)&ethbroadcast;
00858   /* multicast destination IP address? */
00859   } else if (ip_addr_ismulticast(ipaddr)) {
00860     /* Hash IP multicast address to MAC address.*/
00861     mcastaddr.addr[0] = 0x01;
00862     mcastaddr.addr[1] = 0x00;
00863     mcastaddr.addr[2] = 0x5e;
00864     mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
00865     mcastaddr.addr[4] = ip4_addr3(ipaddr);
00866     mcastaddr.addr[5] = ip4_addr4(ipaddr);
00867     /* destination Ethernet address is multicast */
00868     dest = &mcastaddr;
00869   /* unicast destination IP address? */
00870   } else {
00871     /* outside local network? */
00872     if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask)) &&
00873         !ip_addr_islinklocal(ipaddr)) {
00874       /* interface has default gateway? */
00875       if (!ip_addr_isany(&netif->gw)) {
00876         /* send to hardware address of default gateway IP address */
00877         ipaddr = &(netif->gw);
00878       /* no default gateway available */
00879       } else {
00880         /* no route to destination error (default gateway missing) */
00881         return ERR_RTE;
00882       }
00883     }
00884 #if LWIP_NETIF_HWADDRHINT
00885     if (netif->addr_hint != NULL) {
00886       /* per-pcb cached entry was given */
00887       u8_t etharp_cached_entry = *(netif->addr_hint);
00888       if (etharp_cached_entry < ARP_TABLE_SIZE) {
00889 #endif /* LWIP_NETIF_HWADDRHINT */
00890         if ((arp_table[etharp_cached_entry].state == ETHARP_STATE_STABLE) &&
00891             (ip_addr_cmp(ipaddr, &arp_table[etharp_cached_entry].ipaddr))) {
00892           /* the per-pcb-cached entry is stable and the right one! */
00893           ETHARP_STATS_INC(etharp.cachehit);
00894           return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr),
00895             &arp_table[etharp_cached_entry].ethaddr);
00896         }
00897 #if LWIP_NETIF_HWADDRHINT
00898       }
00899     }
00900 #endif /* LWIP_NETIF_HWADDRHINT */
00901     /* queue on destination Ethernet address belonging to ipaddr */
00902     return etharp_query(netif, ipaddr, q);
00903   }
00904 
00905   /* continuation for multicast/broadcast destinations */
00906   /* obtain source Ethernet address of the given interface */
00907   /* send packet directly on the link */
00908   return etharp_send_ip(netif, q, (struct eth_addr*)(netif->hwaddr), dest);
00909 }
00910 
00911 /**
00912  * Send an ARP request for the given IP address and/or queue a packet.
00913  *
00914  * If the IP address was not yet in the cache, a pending ARP cache entry
00915  * is added and an ARP request is sent for the given address. The packet
00916  * is queued on this entry.
00917  *
00918  * If the IP address was already pending in the cache, a new ARP request
00919  * is sent for the given address. The packet is queued on this entry.
00920  *
00921  * If the IP address was already stable in the cache, and a packet is
00922  * given, it is directly sent and no ARP request is sent out. 
00923  * 
00924  * If the IP address was already stable in the cache, and no packet is
00925  * given, an ARP request is sent out.
00926  * 
00927  * @param netif The lwIP network interface on which ipaddr
00928  * must be queried for.
00929  * @param ipaddr The IP address to be resolved.
00930  * @param q If non-NULL, a pbuf that must be delivered to the IP address.
00931  * q is not freed by this function.
00932  *
00933  * @note q must only be ONE packet, not a packet queue!
00934  *
00935  * @return
00936  * - ERR_BUF Could not make room for Ethernet header.
00937  * - ERR_MEM Hardware address unknown, and no more ARP entries available
00938  *   to query for address or queue the packet.
00939  * - ERR_MEM Could not queue packet due to memory shortage.
00940  * - ERR_RTE No route to destination (no gateway to external networks).
00941  * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
00942  *
00943  */
00944 err_t
00945 etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
00946 {
00947   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
00948   err_t result = ERR_MEM;
00949   s8_t i; /* ARP entry index */
00950 
00951   /* non-unicast address? */
00952   if (ip_addr_isbroadcast(ipaddr, netif) ||
00953       ip_addr_ismulticast(ipaddr) ||
00954       ip_addr_isany(ipaddr)) {
00955     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
00956     return ERR_ARG;
00957   }
00958 
00959   /* find entry in ARP cache, ask to create entry if queueing packet */
00960   i = find_entry(ipaddr, ETHARP_FLAG_TRY_HARD);
00961 
00962   /* could not find or create entry? */
00963   if (i < 0) {
00964     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not create ARP entry\n"));
00965     if (q) {
00966       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: packet dropped\n"));
00967       ETHARP_STATS_INC(etharp.memerr);
00968     }
00969     return (err_t)i;
00970   }
00971 
00972   /* mark a fresh entry as pending (we just sent a request) */
00973   if (arp_table[i].state == ETHARP_STATE_EMPTY) {
00974     arp_table[i].state = ETHARP_STATE_PENDING;
00975   }
00976 
00977   /* { i is either a STABLE or (new or existing) PENDING entry } */
00978   LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
00979   ((arp_table[i].state == ETHARP_STATE_PENDING) ||
00980    (arp_table[i].state == ETHARP_STATE_STABLE)));
00981 
00982   /* do we have a pending entry? or an implicit query request? */
00983   if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) {
00984     /* try to resolve it; send out ARP request */
00985     result = etharp_request(netif, ipaddr);
00986     if (result != ERR_OK) {
00987       /* ARP request couldn't be sent */
00988       /* We don't re-send arp request in etharp_tmr, but we still queue packets,
00989          since this failure could be temporary, and the next packet calling
00990          etharp_query again could lead to sending the queued packets. */
00991     }
00992     if (q == NULL) {
00993       return result;
00994     }
00995   }
00996 
00997   /* packet given? */
00998   LWIP_ASSERT("q != NULL", q != NULL);
00999   /* stable entry? */
01000   if (arp_table[i].state == ETHARP_STATE_STABLE) {
01001     /* we have a valid IP->Ethernet address mapping */
01002     ETHARP_SET_HINT(netif, i);
01003     /* send the packet */
01004     result = etharp_send_ip(netif, q, srcaddr, &(arp_table[i].ethaddr));
01005   /* pending entry? (either just created or already pending */
01006   } else if (arp_table[i].state == ETHARP_STATE_PENDING) {
01007 #if ARP_QUEUEING /* queue the given q packet */
01008     struct pbuf *p;
01009     int copy_needed = 0;
01010     /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
01011      * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
01012      * PBUF_ROMs can be left as they are, since ROM must not get changed. */
01013     p = q;
01014     while (p) {
01015       LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
01016       if(p->type != PBUF_ROM) {
01017         copy_needed = 1;
01018         break;
01019       }
01020       p = p->next;
01021     }
01022     if(copy_needed) {
01023       /* copy the whole packet into new pbufs */
01024       p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
01025       if(p != NULL) {
01026         if (pbuf_copy(p, q) != ERR_OK) {
01027           pbuf_free(p);
01028           p = NULL;
01029         }
01030       }
01031     } else {
01032       /* referencing the old pbuf is enough */
01033       p = q;
01034       pbuf_ref(p);
01035     }
01036     /* packet could be taken over? */
01037     if (p != NULL) {
01038       /* queue packet ... */
01039       struct etharp_q_entry *new_entry;
01040       /* allocate a new arp queue entry */
01041       new_entry = (struct etharp_q_entry *)memp_malloc(MEMP_ARP_QUEUE);
01042       if (new_entry != NULL) {
01043         new_entry->next = 0;
01044         new_entry->p = p;
01045         if(arp_table[i].q != NULL) {
01046           /* queue was already existent, append the new entry to the end */
01047           struct etharp_q_entry *r;
01048           r = arp_table[i].q;
01049           while (r->next != NULL) {
01050             r = r->next;
01051           }
01052           r->next = new_entry;
01053         } else {
01054           /* queue did not exist, first item in queue */
01055           arp_table[i].q = new_entry;
01056         }
01057         LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
01058         result = ERR_OK;
01059       } else {
01060         /* the pool MEMP_ARP_QUEUE is empty */
01061         pbuf_free(p);
01062         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));
01063         /* { result == ERR_MEM } through initialization */
01064       }
01065     } else {
01066       ETHARP_STATS_INC(etharp.memerr);
01067       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));
01068       /* { result == ERR_MEM } through initialization */
01069     }
01070 #else /* ARP_QUEUEING */
01071     /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
01072     /* { result == ERR_MEM } through initialization */
01073     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
01074 #endif /* ARP_QUEUEING */
01075   }
01076   return result;
01077 }
01078 
01079 /**
01080  * Send a raw ARP packet (opcode and all addresses can be modified)
01081  *
01082  * @param netif the lwip network interface on which to send the ARP packet
01083  * @param ethsrc_addr the source MAC address for the ethernet header
01084  * @param ethdst_addr the destination MAC address for the ethernet header
01085  * @param hwsrc_addr the source MAC address for the ARP protocol header
01086  * @param ipsrc_addr the source IP address for the ARP protocol header
01087  * @param hwdst_addr the destination MAC address for the ARP protocol header
01088  * @param ipdst_addr the destination IP address for the ARP protocol header
01089  * @param opcode the type of the ARP packet
01090  * @return ERR_OK if the ARP packet has been sent
01091  *         ERR_MEM if the ARP packet couldn't be allocated
01092  *         any other err_t on failure
01093  */
01094 #if !LWIP_AUTOIP
01095 static
01096 #endif /* LWIP_AUTOIP */
01097 err_t
01098 etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
01099            const struct eth_addr *ethdst_addr,
01100            const struct eth_addr *hwsrc_addr, const ip_addr_t *ipsrc_addr,
01101            const struct eth_addr *hwdst_addr, const ip_addr_t *ipdst_addr,
01102            const u16_t opcode)
01103 {
01104   struct pbuf *p;
01105   err_t result = ERR_OK;
01106   struct eth_hdr *ethhdr;
01107   struct etharp_hdr *hdr;
01108 #if LWIP_AUTOIP
01109   const u8_t * ethdst_hwaddr;
01110 #endif /* LWIP_AUTOIP */
01111 
01112   /* allocate a pbuf for the outgoing ARP request packet */
01113   p = pbuf_alloc(PBUF_RAW, SIZEOF_ETHARP_PACKET, PBUF_RAM);
01114   /* could allocate a pbuf for an ARP request? */
01115   if (p == NULL) {
01116     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
01117       ("etharp_raw: could not allocate pbuf for ARP request.\n"));
01118     ETHARP_STATS_INC(etharp.memerr);
01119     return ERR_MEM;
01120   }
01121   LWIP_ASSERT("check that first pbuf can hold struct etharp_hdr",
01122               (p->len >= SIZEOF_ETHARP_PACKET));
01123 
01124   ethhdr = (struct eth_hdr *)p->payload;
01125   hdr = (struct etharp_hdr *)((u8_t*)ethhdr + SIZEOF_ETH_HDR);
01126   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_raw: sending raw ARP packet.\n"));
01127   hdr->opcode = htons(opcode);
01128 
01129   LWIP_ASSERT("netif->hwaddr_len must be the same as ETHARP_HWADDR_LEN for etharp!",
01130               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
01131 #if LWIP_AUTOIP
01132   /* If we are using Link-Local, all ARP packets that contain a Link-Local
01133    * 'sender IP address' MUST be sent using link-layer broadcast instead of
01134    * link-layer unicast. (See RFC3927 Section 2.5, last paragraph) */
01135   ethdst_hwaddr = ip_addr_islinklocal(ipsrc_addr) ? (u8_t*)(ethbroadcast.addr) : ethdst_addr->addr;
01136 #endif /* LWIP_AUTOIP */
01137   /* Write the ARP MAC-Addresses */
01138   ETHADDR16_COPY(&hdr->shwaddr, hwsrc_addr);
01139   ETHADDR16_COPY(&hdr->dhwaddr, hwdst_addr);
01140   /* Write the Ethernet MAC-Addresses */
01141 #if LWIP_AUTOIP
01142   ETHADDR16_COPY(&ethhdr->dest, ethdst_hwaddr);
01143 #else  /* LWIP_AUTOIP */
01144   ETHADDR16_COPY(&ethhdr->dest, ethdst_addr);
01145 #endif /* LWIP_AUTOIP */
01146   ETHADDR16_COPY(&ethhdr->src, ethsrc_addr);
01147   /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
01148    * structure packing. */ 
01149   IPADDR2_COPY(&hdr->sipaddr, ipsrc_addr);
01150   IPADDR2_COPY(&hdr->dipaddr, ipdst_addr);
01151 
01152   hdr->hwtype = PP_HTONS(HWTYPE_ETHERNET);
01153   hdr->proto = PP_HTONS(ETHTYPE_IP);
01154   /* set hwlen and protolen */
01155   hdr->hwlen = ETHARP_HWADDR_LEN;
01156   hdr->protolen = sizeof(ip_addr_t);
01157 
01158   ethhdr->type = PP_HTONS(ETHTYPE_ARP);
01159   /* send ARP query */
01160   result = netif->linkoutput(netif, p);
01161   ETHARP_STATS_INC(etharp.xmit);
01162   /* free ARP query packet */
01163   pbuf_free(p);
01164   p = NULL;
01165   /* could not allocate pbuf for ARP request */
01166 
01167   return result;
01168 }
01169 
01170 /**
01171  * Send an ARP request packet asking for ipaddr.
01172  *
01173  * @param netif the lwip network interface on which to send the request
01174  * @param ipaddr the IP address for which to ask
01175  * @return ERR_OK if the request has been sent
01176  *         ERR_MEM if the ARP packet couldn't be allocated
01177  *         any other err_t on failure
01178  */
01179 err_t
01180 etharp_request(struct netif *netif, ip_addr_t *ipaddr)
01181 {
01182   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
01183   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
01184                     (struct eth_addr *)netif->hwaddr, &netif->ip_addr, &ethzero,
01185                     ipaddr, ARP_REQUEST);
01186 }
01187 #endif /* LWIP_ARP */
01188 
01189 /**
01190  * Process received ethernet frames. Using this function instead of directly
01191  * calling ip_input and passing ARP frames through etharp in ethernetif_input,
01192  * the ARP cache is protected from concurrent access.
01193  *
01194  * @param p the recevied packet, p->payload pointing to the ethernet header
01195  * @param netif the network interface on which the packet was received
01196  */
01197 err_t
01198 ethernet_input(struct pbuf *p, struct netif *netif)
01199 {
01200   struct eth_hdr* ethhdr;
01201   u16_t type;
01202 
01203   /* points to packet payload, which starts with an Ethernet header */
01204   ethhdr = (struct eth_hdr *)p->payload;
01205   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE,
01206     ("ethernet_input: dest:%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F", src:%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F":%"X8_F", type:%"X16_F"\n",
01207      (unsigned)ethhdr->dest.addr[0], (unsigned)ethhdr->dest.addr[1], (unsigned)ethhdr->dest.addr[2],
01208      (unsigned)ethhdr->dest.addr[3], (unsigned)ethhdr->dest.addr[4], (unsigned)ethhdr->dest.addr[5],
01209      (unsigned)ethhdr->src.addr[0], (unsigned)ethhdr->src.addr[1], (unsigned)ethhdr->src.addr[2],
01210      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
01211      (unsigned)htons(ethhdr->type)));
01212 
01213   type = ethhdr->type;
01214 #if ETHARP_SUPPORT_VLAN
01215   if (type == PP_HTONS(ETHTYPE_VLAN)) {
01216     struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
01217 #ifdef ETHARP_VLAN_CHECK /* if not, allow all VLANs */
01218     if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
01219       /* silently ignore this packet: not for our VLAN */
01220       pbuf_free(p);
01221       return ERR_OK;
01222     }
01223 #endif /* ETHARP_VLAN_CHECK */
01224     type = vlan->tpid;
01225   }
01226 #endif /* ETHARP_SUPPORT_VLAN */
01227 
01228 #if LWIP_ARP_FILTER_NETIF
01229   netif = LWIP_ARP_FILTER_NETIF_FN(p, netif, htons(type));
01230 #endif /* LWIP_ARP_FILTER_NETIF*/
01231 
01232   switch (type) {
01233 #if LWIP_ARP
01234     /* IP packet? */
01235     case PP_HTONS(ETHTYPE_IP):
01236       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01237         goto free_and_return;
01238       }
01239 #if ETHARP_TRUST_IP_MAC
01240       /* update ARP table */
01241       etharp_ip_input(netif, p);
01242 #endif /* ETHARP_TRUST_IP_MAC */
01243       /* skip Ethernet header */
01244       if(pbuf_header(p, -(s16_t)SIZEOF_ETH_HDR)) {
01245         LWIP_ASSERT("Can't move over header in packet", 0);
01246         goto free_and_return;
01247       } else {
01248         /* pass to IP layer */
01249         ip_input(p, netif);
01250       }
01251       break;
01252       
01253     case PP_HTONS(ETHTYPE_ARP):
01254       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
01255         goto free_and_return;
01256       }
01257       /* pass p to ARP module */
01258       etharp_arp_input(netif, (struct eth_addr*)(netif->hwaddr), p);
01259       break;
01260 #endif /* LWIP_ARP */
01261 #if PPPOE_SUPPORT
01262     case PP_HTONS(ETHTYPE_PPPOEDISC): /* PPP Over Ethernet Discovery Stage */
01263       pppoe_disc_input(netif, p);
01264       break;
01265 
01266     case PP_HTONS(ETHTYPE_PPPOE): /* PPP Over Ethernet Session Stage */
01267       pppoe_data_input(netif, p);
01268       break;
01269 #endif /* PPPOE_SUPPORT */
01270 
01271     default:
01272       ETHARP_STATS_INC(etharp.proterr);
01273       ETHARP_STATS_INC(etharp.drop);
01274       goto free_and_return;
01275   }
01276 
01277   /* This means the pbuf is freed or consumed,
01278      so the caller doesn't have to free it again */
01279   return ERR_OK;
01280 
01281 free_and_return:
01282   pbuf_free(p);
01283   return ERR_OK;
01284 }
01285 #endif /* LWIP_ARP || LWIP_ETHERNET */