Travis Geiselbrecht | 1d0df69 | 2008-09-01 02:26:09 -0700 | [diff] [blame^] | 1 | /** |
| 2 | * @file |
| 3 | * Address Resolution Protocol module for IP over Ethernet |
| 4 | * |
| 5 | * Functionally, ARP is divided into two parts. The first maps an IP address |
| 6 | * to a physical address when sending a packet, and the second part answers |
| 7 | * requests from other machines for our physical address. |
| 8 | * |
| 9 | * This implementation complies with RFC 826 (Ethernet ARP). It supports |
| 10 | * Gratuitious ARP from RFC3220 (IP Mobility Support for IPv4) section 4.6 |
| 11 | * if an interface calls etharp_query(our_netif, its_ip_addr, NULL) upon |
| 12 | * address change. |
| 13 | */ |
| 14 | |
| 15 | /* |
| 16 | * Copyright (c) 2001-2003 Swedish Institute of Computer Science. |
| 17 | * Copyright (c) 2003-2004 Leon Woestenberg <leon.woestenberg@axon.tv> |
| 18 | * Copyright (c) 2003-2004 Axon Digital Design B.V., The Netherlands. |
| 19 | * All rights reserved. |
| 20 | * |
| 21 | * Redistribution and use in source and binary forms, with or without modification, |
| 22 | * are permitted provided that the following conditions are met: |
| 23 | * |
| 24 | * 1. Redistributions of source code must retain the above copyright notice, |
| 25 | * this list of conditions and the following disclaimer. |
| 26 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 27 | * this list of conditions and the following disclaimer in the documentation |
| 28 | * and/or other materials provided with the distribution. |
| 29 | * 3. The name of the author may not be used to endorse or promote products |
| 30 | * derived from this software without specific prior written permission. |
| 31 | * |
| 32 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 33 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 34 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT |
| 35 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 36 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 37 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 38 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 39 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
| 40 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY |
| 41 | * OF SUCH DAMAGE. |
| 42 | * |
| 43 | * This file is part of the lwIP TCP/IP stack. |
| 44 | * |
| 45 | */ |
| 46 | |
| 47 | #include "lwip/opt.h" |
| 48 | #include "lwip/inet.h" |
| 49 | #include "netif/etharp.h" |
| 50 | #include "lwip/ip.h" |
| 51 | #include "lwip/stats.h" |
| 52 | |
| 53 | /* ARP needs to inform DHCP of any ARP replies? */ |
| 54 | #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK) |
| 55 | # include "lwip/dhcp.h" |
| 56 | #endif |
| 57 | |
| 58 | /** the time an ARP entry stays valid after its last update, |
| 59 | * (240 * 5) seconds = 20 minutes. |
| 60 | */ |
| 61 | #define ARP_MAXAGE 240 |
| 62 | /** the time an ARP entry stays pending after first request, |
| 63 | * (2 * 5) seconds = 10 seconds. |
| 64 | * |
| 65 | * @internal Keep this number at least 2, otherwise it might |
| 66 | * run out instantly if the timeout occurs directly after a request. |
| 67 | */ |
| 68 | #define ARP_MAXPENDING 2 |
| 69 | |
| 70 | #define HWTYPE_ETHERNET 1 |
| 71 | |
| 72 | /** ARP message types */ |
| 73 | #define ARP_REQUEST 1 |
| 74 | #define ARP_REPLY 2 |
| 75 | |
| 76 | #define ARPH_HWLEN(hdr) (ntohs((hdr)->_hwlen_protolen) >> 8) |
| 77 | #define ARPH_PROTOLEN(hdr) (ntohs((hdr)->_hwlen_protolen) & 0xff) |
| 78 | |
| 79 | #define ARPH_HWLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons(ARPH_PROTOLEN(hdr) | ((len) << 8)) |
| 80 | #define ARPH_PROTOLEN_SET(hdr, len) (hdr)->_hwlen_protolen = htons((len) | (ARPH_HWLEN(hdr) << 8)) |
| 81 | |
| 82 | enum etharp_state { |
| 83 | ETHARP_STATE_EMPTY, |
| 84 | ETHARP_STATE_PENDING, |
| 85 | ETHARP_STATE_STABLE, |
| 86 | /** @internal transitional state used in etharp_tmr() for convenience*/ |
| 87 | ETHARP_STATE_EXPIRED |
| 88 | }; |
| 89 | |
| 90 | struct etharp_entry { |
| 91 | #if ARP_QUEUEING |
| 92 | /** |
| 93 | * Pointer to queue of pending outgoing packets on this ARP entry. |
| 94 | */ |
| 95 | struct pbuf *p; |
| 96 | #endif |
| 97 | struct ip_addr ipaddr; |
| 98 | struct eth_addr ethaddr; |
| 99 | enum etharp_state state; |
| 100 | u8_t ctime; |
| 101 | }; |
| 102 | |
| 103 | static const struct eth_addr ethbroadcast = {{0xff,0xff,0xff,0xff,0xff,0xff}}; |
| 104 | static struct etharp_entry arp_table[ARP_TABLE_SIZE]; |
| 105 | |
| 106 | /** |
| 107 | * Try hard to create a new entry - we want the IP address to appear in |
| 108 | * the cache (even if this means removing an active entry or so). */ |
| 109 | #define ETHARP_TRY_HARD 1 |
| 110 | |
| 111 | static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags); |
| 112 | static err_t update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags); |
| 113 | /** |
| 114 | * Initializes ARP module. |
| 115 | */ |
| 116 | void |
| 117 | etharp_init(void) |
| 118 | { |
| 119 | u8_t i; |
| 120 | /* clear ARP entries */ |
| 121 | for(i = 0; i < ARP_TABLE_SIZE; ++i) { |
| 122 | arp_table[i].state = ETHARP_STATE_EMPTY; |
| 123 | #if ARP_QUEUEING |
| 124 | arp_table[i].p = NULL; |
| 125 | #endif |
| 126 | arp_table[i].ctime = 0; |
| 127 | } |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Clears expired entries in the ARP table. |
| 132 | * |
| 133 | * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds), |
| 134 | * in order to expire entries in the ARP table. |
| 135 | */ |
| 136 | void |
| 137 | etharp_tmr(void) |
| 138 | { |
| 139 | u8_t i; |
| 140 | |
| 141 | LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n")); |
| 142 | /* remove expired entries from the ARP table */ |
| 143 | for (i = 0; i < ARP_TABLE_SIZE; ++i) { |
| 144 | arp_table[i].ctime++; |
| 145 | /* stable entry? */ |
| 146 | if ((arp_table[i].state == ETHARP_STATE_STABLE) && |
| 147 | /* entry has become old? */ |
| 148 | (arp_table[i].ctime >= ARP_MAXAGE)) { |
| 149 | LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired stable entry %"U16_F".\n", (u16_t)i)); |
| 150 | arp_table[i].state = ETHARP_STATE_EXPIRED; |
| 151 | /* pending entry? */ |
| 152 | } else if (arp_table[i].state == ETHARP_STATE_PENDING) { |
| 153 | /* entry unresolved/pending for too long? */ |
| 154 | if (arp_table[i].ctime >= ARP_MAXPENDING) { |
| 155 | LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: expired pending entry %"U16_F".\n", (u16_t)i)); |
| 156 | arp_table[i].state = ETHARP_STATE_EXPIRED; |
| 157 | #if ARP_QUEUEING |
| 158 | } else if (arp_table[i].p != NULL) { |
| 159 | /* resend an ARP query here */ |
| 160 | #endif |
| 161 | } |
| 162 | } |
| 163 | /* clean up entries that have just been expired */ |
| 164 | if (arp_table[i].state == ETHARP_STATE_EXPIRED) { |
| 165 | #if ARP_QUEUEING |
| 166 | /* and empty packet queue */ |
| 167 | if (arp_table[i].p != NULL) { |
| 168 | /* remove all queued packets */ |
| 169 | LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].p))); |
| 170 | pbuf_free(arp_table[i].p); |
| 171 | arp_table[i].p = NULL; |
| 172 | } |
| 173 | #endif |
| 174 | /* recycle entry for re-use */ |
| 175 | arp_table[i].state = ETHARP_STATE_EMPTY; |
| 176 | } |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Search the ARP table for a matching or new entry. |
| 182 | * |
| 183 | * If an IP address is given, return a pending or stable ARP entry that matches |
| 184 | * the address. If no match is found, create a new entry with this address set, |
| 185 | * but in state ETHARP_EMPTY. The caller must check and possibly change the |
| 186 | * state of the returned entry. |
| 187 | * |
| 188 | * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY. |
| 189 | * |
| 190 | * In all cases, attempt to create new entries from an empty entry. If no |
| 191 | * empty entries are available and ETHARP_TRY_HARD flag is set, recycle |
| 192 | * old entries. Heuristic choose the least important entry for recycling. |
| 193 | * |
| 194 | * @param ipaddr IP address to find in ARP cache, or to add if not found. |
| 195 | * @param flags |
| 196 | * - ETHARP_TRY_HARD: Try hard to create a entry by allowing recycling of |
| 197 | * active (stable or pending) entries. |
| 198 | * |
| 199 | * @return The ARP entry index that matched or is created, ERR_MEM if no |
| 200 | * entry is found or could be recycled. |
| 201 | */ |
| 202 | static s8_t find_entry(struct ip_addr *ipaddr, u8_t flags) |
| 203 | { |
| 204 | s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE; |
| 205 | s8_t empty = ARP_TABLE_SIZE; |
| 206 | u8_t i = 0, age_pending = 0, age_stable = 0; |
| 207 | #if ARP_QUEUEING |
| 208 | /* oldest entry with packets on queue */ |
| 209 | s8_t old_queue = ARP_TABLE_SIZE; |
| 210 | /* its age */ |
| 211 | u8_t age_queue = 0; |
| 212 | #endif |
| 213 | |
| 214 | /** |
| 215 | * a) do a search through the cache, remember candidates |
| 216 | * b) select candidate entry |
| 217 | * c) create new entry |
| 218 | */ |
| 219 | |
| 220 | /* a) in a single search sweep, do all of this |
| 221 | * 1) remember the first empty entry (if any) |
| 222 | * 2) remember the oldest stable entry (if any) |
| 223 | * 3) remember the oldest pending entry without queued packets (if any) |
| 224 | * 4) remember the oldest pending entry with queued packets (if any) |
| 225 | * 5) search for a matching IP entry, either pending or stable |
| 226 | * until 5 matches, or all entries are searched for. |
| 227 | */ |
| 228 | |
| 229 | for (i = 0; i < ARP_TABLE_SIZE; ++i) { |
| 230 | /* no empty entry found yet and now we do find one? */ |
| 231 | if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == ETHARP_STATE_EMPTY)) { |
| 232 | LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i)); |
| 233 | /* remember first empty entry */ |
| 234 | empty = i; |
| 235 | } |
| 236 | /* pending entry? */ |
| 237 | else if (arp_table[i].state == ETHARP_STATE_PENDING) { |
| 238 | /* if given, does IP address match IP address in ARP entry? */ |
| 239 | if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) { |
| 240 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i)); |
| 241 | /* found exact IP address match, simply bail out */ |
| 242 | return i; |
| 243 | #if ARP_QUEUEING |
| 244 | /* pending with queued packets? */ |
| 245 | } else if (arp_table[i].p != NULL) { |
| 246 | if (arp_table[i].ctime >= age_queue) { |
| 247 | old_queue = i; |
| 248 | age_queue = arp_table[i].ctime; |
| 249 | } |
| 250 | #endif |
| 251 | /* pending without queued packets? */ |
| 252 | } else { |
| 253 | if (arp_table[i].ctime >= age_pending) { |
| 254 | old_pending = i; |
| 255 | age_pending = arp_table[i].ctime; |
| 256 | } |
| 257 | } |
| 258 | } |
| 259 | /* stable entry? */ |
| 260 | else if (arp_table[i].state == ETHARP_STATE_STABLE) { |
| 261 | /* if given, does IP address match IP address in ARP entry? */ |
| 262 | if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) { |
| 263 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i)); |
| 264 | /* found exact IP address match, simply bail out */ |
| 265 | return i; |
| 266 | /* remember entry with oldest stable entry in oldest, its age in maxtime */ |
| 267 | } else if (arp_table[i].ctime >= age_stable) { |
| 268 | old_stable = i; |
| 269 | age_stable = arp_table[i].ctime; |
| 270 | } |
| 271 | } |
| 272 | } |
| 273 | /* { we have no match } => try to create a new entry */ |
| 274 | |
| 275 | /* no empty entry found and not allowed to recycle? */ |
| 276 | if ((empty == ARP_TABLE_SIZE) && ((flags & ETHARP_TRY_HARD) == 0)) |
| 277 | { |
| 278 | return (s8_t)ERR_MEM; |
| 279 | } |
| 280 | |
| 281 | /* b) choose the least destructive entry to recycle: |
| 282 | * 1) empty entry |
| 283 | * 2) oldest stable entry |
| 284 | * 3) oldest pending entry without queued packets |
| 285 | * 4) oldest pending entry without queued packets |
| 286 | * |
| 287 | * { ETHARP_TRY_HARD is set at this point } |
| 288 | */ |
| 289 | |
| 290 | /* 1) empty entry available? */ |
| 291 | if (empty < ARP_TABLE_SIZE) { |
| 292 | i = empty; |
| 293 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i)); |
| 294 | } |
| 295 | /* 2) found recyclable stable entry? */ |
| 296 | else if (old_stable < ARP_TABLE_SIZE) { |
| 297 | /* recycle oldest stable*/ |
| 298 | i = old_stable; |
| 299 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i)); |
| 300 | #if ARP_QUEUEING |
| 301 | /* no queued packets should exist on stable entries */ |
| 302 | LWIP_ASSERT("arp_table[i].p == NULL", arp_table[i].p == NULL); |
| 303 | #endif |
| 304 | /* 3) found recyclable pending entry without queued packets? */ |
| 305 | } else if (old_pending < ARP_TABLE_SIZE) { |
| 306 | /* recycle oldest pending */ |
| 307 | i = old_pending; |
| 308 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i)); |
| 309 | #if ARP_QUEUEING |
| 310 | /* 4) found recyclable pending entry with queued packets? */ |
| 311 | } else if (old_queue < ARP_TABLE_SIZE) { |
| 312 | /* recycle oldest pending */ |
| 313 | i = old_queue; |
| 314 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].p))); |
| 315 | pbuf_free(arp_table[i].p); |
| 316 | arp_table[i].p = NULL; |
| 317 | #endif |
| 318 | /* no empty or recyclable entries found */ |
| 319 | } else { |
| 320 | return (s8_t)ERR_MEM; |
| 321 | } |
| 322 | |
| 323 | /* { empty or recyclable entry found } */ |
| 324 | LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE); |
| 325 | |
| 326 | /* recycle entry (no-op for an already empty entry) */ |
| 327 | arp_table[i].state = ETHARP_STATE_EMPTY; |
| 328 | |
| 329 | /* IP address given? */ |
| 330 | if (ipaddr != NULL) { |
| 331 | /* set IP address */ |
| 332 | ip_addr_set(&arp_table[i].ipaddr, ipaddr); |
| 333 | } |
| 334 | arp_table[i].ctime = 0; |
| 335 | return (err_t)i; |
| 336 | } |
| 337 | |
| 338 | /** |
| 339 | * Update (or insert) a IP/MAC address pair in the ARP cache. |
| 340 | * |
| 341 | * If a pending entry is resolved, any queued packets will be sent |
| 342 | * at this point. |
| 343 | * |
| 344 | * @param ipaddr IP address of the inserted ARP entry. |
| 345 | * @param ethaddr Ethernet address of the inserted ARP entry. |
| 346 | * @param flags Defines behaviour: |
| 347 | * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified, |
| 348 | * only existing ARP entries will be updated. |
| 349 | * |
| 350 | * @return |
| 351 | * - ERR_OK Succesfully updated ARP cache. |
| 352 | * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set. |
| 353 | * - ERR_ARG Non-unicast address given, those will not appear in ARP cache. |
| 354 | * |
| 355 | * @see pbuf_free() |
| 356 | */ |
| 357 | static err_t |
| 358 | update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags) |
| 359 | { |
| 360 | s8_t i, k; |
| 361 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 3, ("update_arp_entry()\n")); |
| 362 | LWIP_ASSERT("netif->hwaddr_len != 0", netif->hwaddr_len != 0); |
| 363 | LWIP_DEBUGF(ETHARP_DEBUG | 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", |
| 364 | ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr), |
| 365 | ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2], |
| 366 | ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5])); |
| 367 | /* non-unicast address? */ |
| 368 | if (ip_addr_isany(ipaddr) || |
| 369 | ip_addr_isbroadcast(ipaddr, netif) || |
| 370 | ip_addr_ismulticast(ipaddr)) { |
| 371 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n")); |
| 372 | return ERR_ARG; |
| 373 | } |
| 374 | /* find or create ARP entry */ |
| 375 | i = find_entry(ipaddr, flags); |
| 376 | /* bail out if no entry could be found */ |
| 377 | if (i < 0) return (err_t)i; |
| 378 | |
| 379 | /* mark it stable */ |
| 380 | arp_table[i].state = ETHARP_STATE_STABLE; |
| 381 | |
| 382 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i)); |
| 383 | /* update address */ |
| 384 | for (k = 0; k < netif->hwaddr_len; ++k) { |
| 385 | arp_table[i].ethaddr.addr[k] = ethaddr->addr[k]; |
| 386 | } |
| 387 | /* reset time stamp */ |
| 388 | arp_table[i].ctime = 0; |
| 389 | /* this is where we will send out queued packets! */ |
| 390 | #if ARP_QUEUEING |
| 391 | while (arp_table[i].p != NULL) { |
| 392 | /* get the first packet on the queue */ |
| 393 | struct pbuf *p = arp_table[i].p; |
| 394 | /* Ethernet header */ |
| 395 | struct eth_hdr *ethhdr = p->payload; |
| 396 | /* remember (and reference) remainder of queue */ |
| 397 | /* note: this will also terminate the p pbuf chain */ |
| 398 | arp_table[i].p = pbuf_dequeue(p); |
| 399 | /* fill-in Ethernet header */ |
| 400 | for (k = 0; k < netif->hwaddr_len; ++k) { |
| 401 | ethhdr->dest.addr[k] = ethaddr->addr[k]; |
| 402 | ethhdr->src.addr[k] = netif->hwaddr[k]; |
| 403 | } |
| 404 | ethhdr->type = htons(ETHTYPE_IP); |
| 405 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: sending queued IP packet %p.\n", (void *)p)); |
| 406 | /* send the queued IP packet */ |
| 407 | netif->linkoutput(netif, p); |
| 408 | /* free the queued IP packet */ |
| 409 | pbuf_free(p); |
| 410 | } |
| 411 | #endif |
| 412 | return ERR_OK; |
| 413 | } |
| 414 | |
| 415 | /** |
| 416 | * Updates the ARP table using the given IP packet. |
| 417 | * |
| 418 | * Uses the incoming IP packet's source address to update the |
| 419 | * ARP cache for the local network. The function does not alter |
| 420 | * or free the packet. This function must be called before the |
| 421 | * packet p is passed to the IP layer. |
| 422 | * |
| 423 | * @param netif The lwIP network interface on which the IP packet pbuf arrived. |
| 424 | * @param pbuf The IP packet that arrived on netif. |
| 425 | * |
| 426 | * @return NULL |
| 427 | * |
| 428 | * @see pbuf_free() |
| 429 | */ |
| 430 | void |
| 431 | etharp_ip_input(struct netif *netif, struct pbuf *p) |
| 432 | { |
| 433 | struct ethip_hdr *hdr; |
| 434 | LWIP_ASSERT("netif != NULL", netif != NULL); |
| 435 | /* Only insert an entry if the source IP address of the |
| 436 | incoming IP packet comes from a host on the local network. */ |
| 437 | hdr = p->payload; |
| 438 | /* source is not on the local network? */ |
| 439 | if (!ip_addr_netcmp(&(hdr->ip.src), &(netif->ip_addr), &(netif->netmask))) { |
| 440 | /* do nothing */ |
| 441 | return; |
| 442 | } |
| 443 | |
| 444 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_ip_input: updating ETHARP table.\n")); |
| 445 | /* update ARP table */ |
| 446 | /* @todo We could use ETHARP_TRY_HARD if we think we are going to talk |
| 447 | * back soon (for example, if the destination IP address is ours. */ |
| 448 | update_arp_entry(netif, &(hdr->ip.src), &(hdr->eth.src), 0); |
| 449 | } |
| 450 | |
| 451 | |
| 452 | /** |
| 453 | * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache |
| 454 | * send out queued IP packets. Updates cache with snooped address pairs. |
| 455 | * |
| 456 | * Should be called for incoming ARP packets. The pbuf in the argument |
| 457 | * is freed by this function. |
| 458 | * |
| 459 | * @param netif The lwIP network interface on which the ARP packet pbuf arrived. |
| 460 | * @param pbuf The ARP packet that arrived on netif. Is freed by this function. |
| 461 | * @param ethaddr Ethernet address of netif. |
| 462 | * |
| 463 | * @return NULL |
| 464 | * |
| 465 | * @see pbuf_free() |
| 466 | */ |
| 467 | void |
| 468 | etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p) |
| 469 | { |
| 470 | struct etharp_hdr *hdr; |
| 471 | /* these are aligned properly, whereas the ARP header fields might not be */ |
| 472 | struct ip_addr sipaddr, dipaddr; |
| 473 | u8_t i; |
| 474 | u8_t for_us; |
| 475 | |
| 476 | LWIP_ASSERT("netif != NULL", netif != NULL); |
| 477 | |
| 478 | /* drop short ARP packets */ |
| 479 | if (p->tot_len < sizeof(struct etharp_hdr)) { |
| 480 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 1, ("etharp_arp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len, sizeof(struct etharp_hdr))); |
| 481 | pbuf_free(p); |
| 482 | return; |
| 483 | } |
| 484 | |
| 485 | hdr = p->payload; |
| 486 | |
| 487 | /* get aligned copies of addresses */ |
| 488 | *(struct ip_addr2 *)&sipaddr = hdr->sipaddr; |
| 489 | *(struct ip_addr2 *)&dipaddr = hdr->dipaddr; |
| 490 | |
| 491 | /* this interface is not configured? */ |
| 492 | if (netif->ip_addr.addr == 0) { |
| 493 | for_us = 0; |
| 494 | } else { |
| 495 | /* ARP packet directed to us? */ |
| 496 | for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr)); |
| 497 | } |
| 498 | |
| 499 | /* ARP message directed to us? */ |
| 500 | if (for_us) { |
| 501 | /* add IP address in ARP cache; assume requester wants to talk to us. |
| 502 | * can result in directly sending the queued packets for this host. */ |
| 503 | update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), ETHARP_TRY_HARD); |
| 504 | /* ARP message not directed to us? */ |
| 505 | } else { |
| 506 | /* update the source IP address in the cache, if present */ |
| 507 | update_arp_entry(netif, &sipaddr, &(hdr->shwaddr), 0); |
| 508 | } |
| 509 | |
| 510 | /* now act on the message itself */ |
| 511 | switch (htons(hdr->opcode)) { |
| 512 | /* ARP request? */ |
| 513 | case ARP_REQUEST: |
| 514 | /* ARP request. If it asked for our address, we send out a |
| 515 | * reply. In any case, we time-stamp any existing ARP entry, |
| 516 | * and possiby send out an IP packet that was queued on it. */ |
| 517 | |
| 518 | LWIP_DEBUGF (ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP request\n")); |
| 519 | /* ARP request for our address? */ |
| 520 | if (for_us) { |
| 521 | |
| 522 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: replying to ARP request for our IP address\n")); |
| 523 | /* re-use pbuf to send ARP reply */ |
| 524 | hdr->opcode = htons(ARP_REPLY); |
| 525 | |
| 526 | hdr->dipaddr = hdr->sipaddr; |
| 527 | hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr; |
| 528 | |
| 529 | for(i = 0; i < netif->hwaddr_len; ++i) { |
| 530 | hdr->dhwaddr.addr[i] = hdr->shwaddr.addr[i]; |
| 531 | hdr->shwaddr.addr[i] = ethaddr->addr[i]; |
| 532 | hdr->ethhdr.dest.addr[i] = hdr->dhwaddr.addr[i]; |
| 533 | hdr->ethhdr.src.addr[i] = ethaddr->addr[i]; |
| 534 | } |
| 535 | |
| 536 | hdr->hwtype = htons(HWTYPE_ETHERNET); |
| 537 | ARPH_HWLEN_SET(hdr, netif->hwaddr_len); |
| 538 | |
| 539 | hdr->proto = htons(ETHTYPE_IP); |
| 540 | ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr)); |
| 541 | |
| 542 | hdr->ethhdr.type = htons(ETHTYPE_ARP); |
| 543 | /* return ARP reply */ |
| 544 | netif->linkoutput(netif, p); |
| 545 | /* we are not configured? */ |
| 546 | } else if (netif->ip_addr.addr == 0) { |
| 547 | /* { for_us == 0 and netif->ip_addr.addr == 0 } */ |
| 548 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: we are unconfigured, ARP request ignored.\n")); |
| 549 | /* request was not directed to us */ |
| 550 | } else { |
| 551 | /* { for_us == 0 and netif->ip_addr.addr != 0 } */ |
| 552 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n")); |
| 553 | } |
| 554 | break; |
| 555 | case ARP_REPLY: |
| 556 | /* ARP reply. We already updated the ARP cache earlier. */ |
| 557 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n")); |
| 558 | #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK) |
| 559 | /* DHCP wants to know about ARP replies from any host with an |
| 560 | * IP address also offered to us by the DHCP server. We do not |
| 561 | * want to take a duplicate IP address on a single network. |
| 562 | * @todo How should we handle redundant (fail-over) interfaces? |
| 563 | * */ |
| 564 | dhcp_arp_reply(netif, &sipaddr); |
| 565 | #endif |
| 566 | break; |
| 567 | default: |
| 568 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_arp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode))); |
| 569 | break; |
| 570 | } |
| 571 | /* free ARP packet */ |
| 572 | pbuf_free(p); |
| 573 | } |
| 574 | |
| 575 | /** |
| 576 | * Resolve and fill-in Ethernet address header for outgoing packet. |
| 577 | * |
| 578 | * For IP multicast and broadcast, corresponding Ethernet addresses |
| 579 | * are selected and the packet is transmitted on the link. |
| 580 | * |
| 581 | * For unicast addresses, the packet is submitted to etharp_query(). In |
| 582 | * case the IP address is outside the local network, the IP address of |
| 583 | * the gateway is used. |
| 584 | * |
| 585 | * @param netif The lwIP network interface which the IP packet will be sent on. |
| 586 | * @param ipaddr The IP address of the packet destination. |
| 587 | * @param pbuf The pbuf(s) containing the IP packet to be sent. |
| 588 | * |
| 589 | * @return |
| 590 | * - ERR_RTE No route to destination (no gateway to external networks), |
| 591 | * or the return type of either etharp_query() or netif->linkoutput(). |
| 592 | */ |
| 593 | err_t |
| 594 | etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q) |
| 595 | { |
| 596 | struct eth_addr *dest, *srcaddr, mcastaddr; |
| 597 | struct eth_hdr *ethhdr; |
| 598 | u8_t i; |
| 599 | |
| 600 | /* make room for Ethernet header - should not fail */ |
| 601 | if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) { |
| 602 | /* bail out */ |
| 603 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n")); |
| 604 | LINK_STATS_INC(link.lenerr); |
| 605 | return ERR_BUF; |
| 606 | } |
| 607 | |
| 608 | /* assume unresolved Ethernet address */ |
| 609 | dest = NULL; |
| 610 | /* Determine on destination hardware address. Broadcasts and multicasts |
| 611 | * are special, other IP addresses are looked up in the ARP table. */ |
| 612 | |
| 613 | /* broadcast destination IP address? */ |
| 614 | if (ip_addr_isbroadcast(ipaddr, netif)) { |
| 615 | /* broadcast on Ethernet also */ |
| 616 | dest = (struct eth_addr *)ðbroadcast; |
| 617 | /* multicast destination IP address? */ |
| 618 | } else if (ip_addr_ismulticast(ipaddr)) { |
| 619 | /* Hash IP multicast address to MAC address.*/ |
| 620 | mcastaddr.addr[0] = 0x01; |
| 621 | mcastaddr.addr[1] = 0x00; |
| 622 | mcastaddr.addr[2] = 0x5e; |
| 623 | mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f; |
| 624 | mcastaddr.addr[4] = ip4_addr3(ipaddr); |
| 625 | mcastaddr.addr[5] = ip4_addr4(ipaddr); |
| 626 | /* destination Ethernet address is multicast */ |
| 627 | dest = &mcastaddr; |
| 628 | /* unicast destination IP address? */ |
| 629 | } else { |
| 630 | /* outside local network? */ |
| 631 | if (!ip_addr_netcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))) { |
| 632 | /* interface has default gateway? */ |
| 633 | if (netif->gw.addr != 0) { |
| 634 | /* send to hardware address of default gateway IP address */ |
| 635 | ipaddr = &(netif->gw); |
| 636 | /* no default gateway available */ |
| 637 | } else { |
| 638 | /* no route to destination error (default gateway missing) */ |
| 639 | return ERR_RTE; |
| 640 | } |
| 641 | } |
| 642 | /* queue on destination Ethernet address belonging to ipaddr */ |
| 643 | return etharp_query(netif, ipaddr, q); |
| 644 | } |
| 645 | |
| 646 | /* continuation for multicast/broadcast destinations */ |
| 647 | /* obtain source Ethernet address of the given interface */ |
| 648 | srcaddr = (struct eth_addr *)netif->hwaddr; |
| 649 | ethhdr = q->payload; |
| 650 | for (i = 0; i < netif->hwaddr_len; i++) { |
| 651 | ethhdr->dest.addr[i] = dest->addr[i]; |
| 652 | ethhdr->src.addr[i] = srcaddr->addr[i]; |
| 653 | } |
| 654 | ethhdr->type = htons(ETHTYPE_IP); |
| 655 | /* send packet directly on the link */ |
| 656 | return netif->linkoutput(netif, q); |
| 657 | } |
| 658 | |
| 659 | /** |
| 660 | * Send an ARP request for the given IP address and/or queue a packet. |
| 661 | * |
| 662 | * If the IP address was not yet in the cache, a pending ARP cache entry |
| 663 | * is added and an ARP request is sent for the given address. The packet |
| 664 | * is queued on this entry. |
| 665 | * |
| 666 | * If the IP address was already pending in the cache, a new ARP request |
| 667 | * is sent for the given address. The packet is queued on this entry. |
| 668 | * |
| 669 | * If the IP address was already stable in the cache, and a packet is |
| 670 | * given, it is directly sent and no ARP request is sent out. |
| 671 | * |
| 672 | * If the IP address was already stable in the cache, and no packet is |
| 673 | * given, an ARP request is sent out. |
| 674 | * |
| 675 | * @param netif The lwIP network interface on which ipaddr |
| 676 | * must be queried for. |
| 677 | * @param ipaddr The IP address to be resolved. |
| 678 | * @param q If non-NULL, a pbuf that must be delivered to the IP address. |
| 679 | * q is not freed by this function. |
| 680 | * |
| 681 | * @return |
| 682 | * - ERR_BUF Could not make room for Ethernet header. |
| 683 | * - ERR_MEM Hardware address unknown, and no more ARP entries available |
| 684 | * to query for address or queue the packet. |
| 685 | * - ERR_MEM Could not queue packet due to memory shortage. |
| 686 | * - ERR_RTE No route to destination (no gateway to external networks). |
| 687 | * - ERR_ARG Non-unicast address given, those will not appear in ARP cache. |
| 688 | * |
| 689 | */ |
| 690 | err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q) |
| 691 | { |
| 692 | struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr; |
| 693 | err_t result = ERR_MEM; |
| 694 | s8_t i; /* ARP entry index */ |
| 695 | u8_t k; /* Ethernet address octet index */ |
| 696 | |
| 697 | /* non-unicast address? */ |
| 698 | if (ip_addr_isbroadcast(ipaddr, netif) || |
| 699 | ip_addr_ismulticast(ipaddr) || |
| 700 | ip_addr_isany(ipaddr)) { |
| 701 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n")); |
| 702 | return ERR_ARG; |
| 703 | } |
| 704 | |
| 705 | /* find entry in ARP cache, ask to create entry if queueing packet */ |
| 706 | i = find_entry(ipaddr, ETHARP_TRY_HARD); |
| 707 | |
| 708 | /* could not find or create entry? */ |
| 709 | if (i < 0) |
| 710 | { |
| 711 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not create ARP entry\n")); |
| 712 | if (q) LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: packet dropped\n")); |
| 713 | return (err_t)i; |
| 714 | } |
| 715 | |
| 716 | /* mark a fresh entry as pending (we just sent a request) */ |
| 717 | if (arp_table[i].state == ETHARP_STATE_EMPTY) { |
| 718 | arp_table[i].state = ETHARP_STATE_PENDING; |
| 719 | } |
| 720 | |
| 721 | /* { i is either a STABLE or (new or existing) PENDING entry } */ |
| 722 | LWIP_ASSERT("arp_table[i].state == PENDING or STABLE", |
| 723 | ((arp_table[i].state == ETHARP_STATE_PENDING) || |
| 724 | (arp_table[i].state == ETHARP_STATE_STABLE))); |
| 725 | |
| 726 | /* do we have a pending entry? or an implicit query request? */ |
| 727 | if ((arp_table[i].state == ETHARP_STATE_PENDING) || (q == NULL)) { |
| 728 | /* try to resolve it; send out ARP request */ |
| 729 | result = etharp_request(netif, ipaddr); |
| 730 | } |
| 731 | |
| 732 | /* packet given? */ |
| 733 | if (q != NULL) { |
| 734 | /* stable entry? */ |
| 735 | if (arp_table[i].state == ETHARP_STATE_STABLE) { |
| 736 | /* we have a valid IP->Ethernet address mapping, |
| 737 | * fill in the Ethernet header for the outgoing packet */ |
| 738 | struct eth_hdr *ethhdr = q->payload; |
| 739 | for(k = 0; k < netif->hwaddr_len; k++) { |
| 740 | ethhdr->dest.addr[k] = arp_table[i].ethaddr.addr[k]; |
| 741 | ethhdr->src.addr[k] = srcaddr->addr[k]; |
| 742 | } |
| 743 | ethhdr->type = htons(ETHTYPE_IP); |
| 744 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: sending packet %p\n", (void *)q)); |
| 745 | /* send the packet */ |
| 746 | result = netif->linkoutput(netif, q); |
| 747 | /* pending entry? (either just created or already pending */ |
| 748 | } else if (arp_table[i].state == ETHARP_STATE_PENDING) { |
| 749 | #if ARP_QUEUEING /* queue the given q packet */ |
| 750 | struct pbuf *p; |
| 751 | /* copy any PBUF_REF referenced payloads into PBUF_RAM */ |
| 752 | /* (the caller of lwIP assumes the referenced payload can be |
| 753 | * freed after it returns from the lwIP call that brought us here) */ |
| 754 | p = pbuf_take(q); |
| 755 | /* packet could be taken over? */ |
| 756 | if (p != NULL) { |
| 757 | /* queue packet ... */ |
| 758 | if (arp_table[i].p == NULL) { |
| 759 | /* ... in the empty queue */ |
| 760 | pbuf_ref(p); |
| 761 | arp_table[i].p = p; |
| 762 | #if 0 /* multi-packet-queueing disabled, see bug #11400 */ |
| 763 | } else { |
| 764 | /* ... at tail of non-empty queue */ |
| 765 | pbuf_queue(arp_table[i].p, p); |
| 766 | #endif |
| 767 | } |
| 768 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i)); |
| 769 | result = ERR_OK; |
| 770 | } else { |
| 771 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q)); |
| 772 | /* { result == ERR_MEM } through initialization */ |
| 773 | } |
| 774 | #else /* ARP_QUEUEING == 0 */ |
| 775 | /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */ |
| 776 | /* { result == ERR_MEM } through initialization */ |
| 777 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q)); |
| 778 | #endif |
| 779 | } |
| 780 | } |
| 781 | return result; |
| 782 | } |
| 783 | |
| 784 | err_t etharp_request(struct netif *netif, struct ip_addr *ipaddr) |
| 785 | { |
| 786 | struct pbuf *p; |
| 787 | struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr; |
| 788 | err_t result = ERR_OK; |
| 789 | u8_t k; /* ARP entry index */ |
| 790 | |
| 791 | /* allocate a pbuf for the outgoing ARP request packet */ |
| 792 | p = pbuf_alloc(PBUF_LINK, sizeof(struct etharp_hdr), PBUF_RAM); |
| 793 | /* could allocate a pbuf for an ARP request? */ |
| 794 | if (p != NULL) { |
| 795 | struct etharp_hdr *hdr = p->payload; |
| 796 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_request: sending ARP request.\n")); |
| 797 | hdr->opcode = htons(ARP_REQUEST); |
| 798 | for (k = 0; k < netif->hwaddr_len; k++) |
| 799 | { |
| 800 | hdr->shwaddr.addr[k] = srcaddr->addr[k]; |
| 801 | /* the hardware address is what we ask for, in |
| 802 | * a request it is a don't-care value, we use zeroes */ |
| 803 | hdr->dhwaddr.addr[k] = 0x00; |
| 804 | } |
| 805 | hdr->dipaddr = *(struct ip_addr2 *)ipaddr; |
| 806 | hdr->sipaddr = *(struct ip_addr2 *)&netif->ip_addr; |
| 807 | |
| 808 | hdr->hwtype = htons(HWTYPE_ETHERNET); |
| 809 | ARPH_HWLEN_SET(hdr, netif->hwaddr_len); |
| 810 | |
| 811 | hdr->proto = htons(ETHTYPE_IP); |
| 812 | ARPH_PROTOLEN_SET(hdr, sizeof(struct ip_addr)); |
| 813 | for (k = 0; k < netif->hwaddr_len; ++k) |
| 814 | { |
| 815 | /* broadcast to all network interfaces on the local network */ |
| 816 | hdr->ethhdr.dest.addr[k] = 0xff; |
| 817 | hdr->ethhdr.src.addr[k] = srcaddr->addr[k]; |
| 818 | } |
| 819 | hdr->ethhdr.type = htons(ETHTYPE_ARP); |
| 820 | /* send ARP query */ |
| 821 | result = netif->linkoutput(netif, p); |
| 822 | /* free ARP query packet */ |
| 823 | pbuf_free(p); |
| 824 | p = NULL; |
| 825 | /* could not allocate pbuf for ARP request */ |
| 826 | } else { |
| 827 | result = ERR_MEM; |
| 828 | LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_request: could not allocate pbuf for ARP request.\n")); |
| 829 | } |
| 830 | return result; |
| 831 | } |