bsd/netinet/in_arp.c

   1 /*
   2  * Copyright (c) 2004-2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * Copyright (c) 1982, 1989, 1993
  30  *      The Regents of the University of California.  All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  */
  61
  62 #include <kern/debug.h>
  63 #include <netinet/in_arp.h>
  64 #include <sys/types.h>
  65 #include <sys/param.h>
  66 #include <sys/kernel_types.h>
  67 #include <sys/syslog.h>
  68 #include <sys/systm.h>
  69 #include <sys/time.h>
  70 #include <sys/kernel.h>
  71 #include <sys/mbuf.h>
  72 #include <sys/sysctl.h>
  73 #include <string.h>
  74 #include <net/if_arp.h>
  75 #include <net/if_dl.h>
  76 #include <net/dlil.h>
  77 #include <net/route.h>
  78 #include <netinet/if_ether.h>
  79 #include <netinet/in_var.h>
  80
  81 #define SIN(s) ((struct sockaddr_in *)s)
  82 #define CONST_LLADDR(s) ((const u_char*)((s)->sdl_data + (s)->sdl_nlen))
  83 #define rt_expire rt_rmx.rmx_expire
  84
  85 static const size_t MAX_HW_LEN = 10;
  86
  87 SYSCTL_DECL(_net_link_ether);
  88 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW|CTLFLAG_LOCKED, 0, "");
  89
  90 /* timer values */
  91 static int arpt_prune = (5*60*1); /* walk list every 5 minutes */
  92 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
  93 static int arpt_down = 20;      /* once declared down, don't send for 20 sec */
  94
  95 /* Apple Hardware SUM16 checksuming */
  96 int apple_hwcksum_tx = 1;
  97 int apple_hwcksum_rx = 1;
  98
  99 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW,
 100            &arpt_prune, 0, "");
 101 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
 102            &arpt_keep, 0, "");
 103 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, host_down_time, CTLFLAG_RW,
 104            &arpt_down, 0, "");
 105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, apple_hwcksum_tx, CTLFLAG_RW,
 106            &apple_hwcksum_tx, 0, "");
 107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, apple_hwcksum_rx, CTLFLAG_RW,
 108            &apple_hwcksum_rx, 0, "");
 109
 110 struct llinfo_arp {
 111         LIST_ENTRY(llinfo_arp) la_le;
 112         struct  rtentry *la_rt;
 113         struct  mbuf *la_hold;          /* last packet until resolved/timeout */
 114         long    la_asked;               /* last time we QUERIED for this addr */
 115 };
 116
 117 static LIST_HEAD(, llinfo_arp) llinfo_arp;
 118
 119 static int      arp_inuse, arp_allocated;
 120
 121 static int      arp_maxtries = 5;
 122 static int      useloopback = 1; /* use loopback interface for local traffic */
 123 static int      arp_proxyall = 0;
 124 static int      arp_sendllconflict = 0;
 125
 126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
 127            &arp_maxtries, 0, "");
 128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
 129            &useloopback, 0, "");
 130 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
 131            &arp_proxyall, 0, "");
 132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, sendllconflict, CTLFLAG_RW,
 133            &arp_sendllconflict, 0, "");
 134
 135 static int log_arp_warnings = 0;
 136
 137 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_warnings, CTLFLAG_RW,
 138         &log_arp_warnings, 0,
 139         "log arp warning messages");
 140
 141 static int keep_announcements = 1;
 142 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, keep_announcements, CTLFLAG_RW,
 143         &keep_announcements, 0,
 144         "keep arp announcements");
 145
 146 static int send_conflicting_probes = 1;
 147 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, send_conflicting_probes, CTLFLAG_RW,
 148         &send_conflicting_probes, 0,
 149         "send conflicting link-local arp probes");
 150
 151 extern u_int32_t        ipv4_ll_arp_aware;
 152
 153 /*
 154  * Free an arp entry.
 155  */
 156 static void
 157 arptfree(
 158         struct llinfo_arp *la)
 159 {
 160         struct rtentry *rt = la->la_rt;
 161         struct sockaddr_dl *sdl;
 162         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 163         if (rt == 0)
 164                 panic("arptfree");
 165         if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) &&
 166             sdl->sdl_family == AF_LINK) {
 167                 sdl->sdl_alen = 0;
 168                 la->la_asked = 0;
 169                 rt->rt_flags &= ~RTF_REJECT;
 170                 return;
 171         }
 172         rtrequest_locked(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt),
 173                         0, (struct rtentry **)0);
 174 }
 175
 176 /*
 177  * Timeout routine.  Age arp_tab entries periodically.
 178  */
 179 /* ARGSUSED */
 180 static void
 181 arptimer(void *ignored_arg)
 182 {
 183 #pragma unused (ignored_arg)
 184         struct llinfo_arp *la, *ola;
 185         struct timeval timenow;
 186
 187         lck_mtx_lock(rt_mtx);
 188         la = llinfo_arp.lh_first;
 189         getmicrotime(&timenow);
 190         while ((ola = la) != 0) {
 191                 struct rtentry *rt = la->la_rt;
 192                 la = la->la_le.le_next;
 193                 if (rt->rt_expire && rt->rt_expire <= timenow.tv_sec)
 194                         arptfree(ola); /* timer has expired, clear */
 195         }
 196         lck_mtx_unlock(rt_mtx);
 197         timeout(arptimer, (caddr_t)0, arpt_prune * hz);
 198 }
 199
 200 /*
 201  * Parallel to llc_rtrequest.
 202  */
 203 static void
 204 arp_rtrequest(
 205         int req,
 206         struct rtentry *rt,
 207         __unused struct sockaddr *sa)
 208 {
 209         struct sockaddr *gate = rt->rt_gateway;
 210         struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
 211         static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK, 0, 0, 0, 0, 0, {0}};
 212         static int arpinit_done;
 213         struct timeval timenow;
 214
 215         if (!arpinit_done) {
 216                 arpinit_done = 1;
 217                 LIST_INIT(&llinfo_arp);
 218                 timeout(arptimer, (caddr_t)0, hz);
 219         }
 220         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 221
 222         if (rt->rt_flags & RTF_GATEWAY)
 223                 return;
 224         getmicrotime(&timenow);
 225         switch (req) {
 226
 227         case RTM_ADD:
 228                 /*
 229                  * XXX: If this is a manually added route to interface
 230                  * such as older version of routed or gated might provide,
 231                  * restore cloning bit.
 232                  */
 233                 if ((rt->rt_flags & RTF_HOST) == 0 &&
 234                     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
 235                         rt->rt_flags |= RTF_CLONING;
 236                 if (rt->rt_flags & RTF_CLONING) {
 237                         /*
 238                          * Case 1: This route should come from a route to iface.
 239                          */
 240                         rt_setgate(rt, rt_key(rt),
 241                                         (struct sockaddr *)&null_sdl);
 242                         gate = rt->rt_gateway;
 243                         SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 244                         SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 245                         /* In case we're called before 1.0 sec. has elapsed */
 246                         rt->rt_expire = MAX(timenow.tv_sec, 1);
 247                         break;
 248                 }
 249                 /* Announce a new entry if requested. */
 250                 if (rt->rt_flags & RTF_ANNOUNCE)
 251                         dlil_send_arp(rt->rt_ifp, ARPOP_REQUEST, SDL(gate), rt_key(rt), (struct sockaddr_dl *)rt_key(rt), NULL);
 252                 /*FALLTHROUGH*/
 253         case RTM_RESOLVE:
 254                 if (gate->sa_family != AF_LINK ||
 255                     gate->sa_len < sizeof(null_sdl)) {
 256                         if (log_arp_warnings)
 257                                 log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
 258                         break;
 259                 }
 260                 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 261                 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 262                 if (la != 0)
 263                         break; /* This happens on a route change */
 264                 /*
 265                  * Case 2:  This route may come from cloning, or a manual route
 266                  * add with a LL address.
 267                  */
 268                 R_Malloc(la, struct llinfo_arp *, sizeof(*la));
 269                 rt->rt_llinfo = (caddr_t)la;
 270                 if (la == 0) {
 271                         if ( log_arp_warnings)
 272                                 log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
 273                         break;
 274                 }
 275                 arp_inuse++, arp_allocated++;
 276                 Bzero(la, sizeof(*la));
 277                 la->la_rt = rt;
 278                 rt->rt_flags |= RTF_LLINFO;
 279                 LIST_INSERT_HEAD(&llinfo_arp, la, la_le);
 280
 281 #if INET
 282                 /*
 283                  * This keeps the multicast addresses from showing up
 284                  * in `arp -a' listings as unresolved.  It's not actually
 285                  * functional.  Then the same for broadcast.
 286                  */
 287                 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr))) {
 288                         dlil_resolve_multi(rt->rt_ifp, rt_key(rt), gate, sizeof(struct sockaddr_dl));
 289                         rt->rt_expire = 0;
 290                 }
 291                 else if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
 292                         struct sockaddr_dl      *gate_ll = SDL(gate);
 293                         size_t  broadcast_len;
 294                         ifnet_llbroadcast_copy_bytes(rt->rt_ifp, LLADDR(gate_ll),
 295                                                                                  sizeof(gate_ll->sdl_data),
 296                                                                                  &broadcast_len);
 297                         gate_ll->sdl_alen = broadcast_len;
 298                         gate_ll->sdl_family = AF_LINK;
 299                         gate_ll->sdl_len = sizeof(struct sockaddr_dl);
 300                         /* In case we're called before 1.0 sec. has elapsed */
 301                         rt->rt_expire = MAX(timenow.tv_sec, 1);
 302                 }
 303 #endif
 304
 305                 if (SIN(rt_key(rt))->sin_addr.s_addr ==
 306                     (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) {
 307                     /*
 308                      * This test used to be
 309                      *  if (loif.if_flags & IFF_UP)
 310                      * It allowed local traffic to be forced
 311                      * through the hardware by configuring the loopback down.
 312                      * However, it causes problems during network configuration
 313                      * for boards that can't receive packets they send.
 314                      * It is now necessary to clear "useloopback" and remove
 315                      * the route to force traffic out to the hardware.
 316                      */
 317                         rt->rt_expire = 0;
 318                         ifnet_lladdr_copy_bytes(rt->rt_ifp, LLADDR(SDL(gate)), SDL(gate)->sdl_alen = 6);
 319                         if (useloopback)
 320                                 rt->rt_ifp = lo_ifp;
 321
 322                 }
 323                 break;
 324
 325         case RTM_DELETE:
 326                 if (la == 0)
 327                         break;
 328                 arp_inuse--;
 329                 LIST_REMOVE(la, la_le);
 330                 rt->rt_llinfo = NULL;
 331                 rt->rt_flags &= ~RTF_LLINFO;
 332                 if (la->la_hold) {
 333                         m_freem(la->la_hold);
 334                 }
 335                 la->la_hold = NULL;
 336                 R_Free((caddr_t)la);
 337         }
 338 }
 339
 340 /*
 341  * convert hardware address to hex string for logging errors.
 342  */
 343 static const char *
 344 sdl_addr_to_hex(const struct sockaddr_dl *sdl, char * orig_buf, int buflen)
 345 {
 346         char *          buf = orig_buf;
 347         int             i;
 348         const u_char *  lladdr = (u_char *)sdl->sdl_data;
 349         int                     maxbytes = buflen / 3;
 350
 351         if (maxbytes > sdl->sdl_alen) {
 352                 maxbytes = sdl->sdl_alen;
 353         }
 354         *buf = '\0';
 355         for (i = 0; i < maxbytes; i++) {
 356                 snprintf(buf, 3, "%02x", lladdr[i]);
 357                 buf += 2;
 358                 *buf = (i == maxbytes - 1) ? '\0' : ':';
 359                 buf++;
 360         }
 361         return (orig_buf);
 362 }
 363
 364 /*
 365  * arp_lookup_route will lookup the route for a given address.
 366  *
 367  * The routing lock must be held. The address must be for a
 368  * host on a local network on this interface.
 369  */
 370 static errno_t
 371 arp_lookup_route(
 372         const struct in_addr *addr,
 373         int     create,
 374         int proxy,
 375         route_t *route,
 376         unsigned int ifscope)
 377 {
 378         struct sockaddr_inarp sin = {sizeof(sin), AF_INET, 0, {0}, {0}, 0, 0};
 379         const char *why = NULL;
 380         errno_t error = 0;
 381
 382         // Caller is responsible for taking the routing lock
 383         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 384
 385         sin.sin_addr.s_addr = addr->s_addr;
 386         sin.sin_other = proxy ? SIN_PROXY : 0;
 387
 388         *route = rtalloc1_scoped_locked((struct sockaddr*)&sin,
 389             create, 0, ifscope);
 390         if (*route == NULL)
 391                 return ENETUNREACH;
 392
 393         rtunref(*route);
 394
 395         if ((*route)->rt_flags & RTF_GATEWAY) {
 396                 why = "host is not on local network";
 397
 398                 /* If there are no references to this route, purge it */
 399                 if ((*route)->rt_refcnt <= 0 && ((*route)->rt_flags & RTF_WASCLONED) != 0) {
 400                         rtrequest_locked(RTM_DELETE,
 401                                         (struct sockaddr *)rt_key(*route),
 402                                         (*route)->rt_gateway, rt_mask(*route),
 403                                         (*route)->rt_flags, 0);
 404                 }
 405                 *route = NULL;
 406                 error = ENETUNREACH;
 407         }
 408         else if (((*route)->rt_flags & RTF_LLINFO) == 0) {
 409                 why = "could not allocate llinfo";
 410                 *route = NULL;
 411                 error = ENOMEM;
 412         }
 413         else if ((*route)->rt_gateway->sa_family != AF_LINK) {
 414                 why = "gateway route is not ours";
 415                 *route = NULL;
 416                 error = EPROTONOSUPPORT;
 417         }
 418
 419         if (why && create && log_arp_warnings) {
 420                 char    tmp[MAX_IPv4_STR_LEN];
 421                 log(LOG_DEBUG, "arplookup link#%d %s failed: %s\n", ifscope,
 422                         inet_ntop(AF_INET, addr, tmp, sizeof(tmp)), why);
 423         }
 424
 425         return error;
 426 }
 427
 428
 429 __private_extern__ errno_t
 430 arp_route_to_gateway_route(
 431         const struct sockaddr *net_dest,
 432         route_t hint,
 433         route_t *out_route);
 434 /*
 435  * arp_route_to_gateway_route will find the gateway route for a given route.
 436  *
 437  * If the route is down, look the route up again.
 438  * If the route goes through a gateway, get the route to the gateway.
 439  * If the gateway route is down, look it up again.
 440  * If the route is set to reject, verify it hasn't expired.
 441  */
 442 __private_extern__ errno_t
 443 arp_route_to_gateway_route(
 444         const struct sockaddr *net_dest,
 445         route_t hint,
 446         route_t *out_route)
 447 {
 448         struct timeval timenow;
 449         route_t route = hint;
 450         *out_route = NULL;
 451
 452         /* If we got a hint from the higher layers, check it out */
 453         if (route) {
 454                 lck_mtx_lock(rt_mtx);
 455
 456                 if ((route->rt_flags & RTF_UP) == 0) {
 457                         /* route is down, find a new one */
 458                         hint = route = rtalloc1_scoped_locked(net_dest,
 459                             1, 0, route->rt_ifp->if_index);
 460                         if (hint) {
 461                                 rtunref(hint);
 462                         }
 463                         else {
 464                                 /* No route to host */
 465                                 lck_mtx_unlock(rt_mtx);
 466                                 return EHOSTUNREACH;
 467                         }
 468                 }
 469
 470                 if (route->rt_flags & RTF_GATEWAY) {
 471                         /*
 472                          * We need the gateway route. If it is NULL or down,
 473                          * look it up.
 474                          */
 475                         if (route->rt_gwroute == 0 ||
 476                                 (route->rt_gwroute->rt_flags & RTF_UP) == 0) {
 477                                 if (route->rt_gwroute != 0)
 478                                         rtfree_locked(route->rt_gwroute);
 479
 480                                 route->rt_gwroute = rtalloc1_scoped_locked(
 481                                     route->rt_gateway, 1, 0,
 482                                     route->rt_ifp->if_index);
 483                                 if (route->rt_gwroute == 0) {
 484                                         lck_mtx_unlock(rt_mtx);
 485                                         return EHOSTUNREACH;
 486                                 }
 487                         }
 488
 489                         route = route->rt_gwroute;
 490                 }
 491
 492                 if (route->rt_flags & RTF_REJECT) {
 493                         getmicrotime(&timenow);
 494                         if (route->rt_rmx.rmx_expire == 0 ||
 495                                 timenow.tv_sec < route->rt_rmx.rmx_expire) {
 496                                 lck_mtx_unlock(rt_mtx);
 497                                 return route == hint ? EHOSTDOWN : EHOSTUNREACH;
 498                         }
 499                 }
 500
 501                 lck_mtx_unlock(rt_mtx);
 502         }
 503
 504         *out_route = route;
 505         return 0;
 506 }
 507
 508 errno_t
 509 arp_lookup_ip(
 510         ifnet_t ifp,
 511         const struct sockaddr_in *net_dest,
 512         struct sockaddr_dl *ll_dest,
 513         size_t  ll_dest_len,
 514         route_t hint,
 515         mbuf_t packet)
 516 {
 517         route_t route = NULL;
 518         errno_t result = 0;
 519         struct sockaddr_dl      *gateway;
 520         struct llinfo_arp       *llinfo;
 521         struct timeval timenow;
 522
 523         if (net_dest->sin_family != AF_INET)
 524                 return EAFNOSUPPORT;
 525
 526         if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 527                 return ENETDOWN;
 528
 529         /*
 530          * If we were given a route, verify the route and grab the gateway
 531          */
 532         if (hint) {
 533                 result = arp_route_to_gateway_route((const struct sockaddr*)net_dest,
 534                                                                                         hint, &route);
 535                 if (result != 0)
 536                         return result;
 537         }
 538
 539         if (packet->m_flags & M_BCAST) {
 540                 u_long  broadcast_len;
 541                 bzero(ll_dest, ll_dest_len);
 542                 result = ifnet_llbroadcast_copy_bytes(ifp, LLADDR(ll_dest), ll_dest_len
 543                                                                                           - offsetof(struct sockaddr_dl,
 544                                                                                           sdl_data), &broadcast_len);
 545                 if (result != 0) {
 546                         return result;
 547                 }
 548
 549                 ll_dest->sdl_alen = broadcast_len;
 550                 ll_dest->sdl_family = AF_LINK;
 551                 ll_dest->sdl_len = sizeof(struct sockaddr_dl);
 552
 553                 return 0;
 554         }
 555         if (packet->m_flags & M_MCAST) {
 556                 return dlil_resolve_multi(ifp, (const struct sockaddr*)net_dest,
 557                                                                    (struct sockaddr*)ll_dest, ll_dest_len);
 558         }
 559
 560         lck_mtx_lock(rt_mtx);
 561
 562         /*
 563          * If we didn't find a route, or the route doesn't have
 564          * link layer information, trigger the creation of the
 565          * route and link layer information.
 566          */
 567         if (route == NULL || route->rt_llinfo == NULL)
 568                 result = arp_lookup_route(&net_dest->sin_addr, 1, 0, &route,
 569                     ifp->if_index);
 570
 571         if (result || route == NULL || route->rt_llinfo == NULL) {
 572                 char    tmp[MAX_IPv4_STR_LEN];
 573                 lck_mtx_unlock(rt_mtx);
 574                 if (log_arp_warnings)
 575                         log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s\n",
 576                                 inet_ntop(AF_INET, &net_dest->sin_addr, tmp, sizeof(tmp)));
 577                 return result;
 578         }
 579
 580         /*
 581          * Now that we have the right route, is it filled in?
 582          */
 583         gateway = SDL(route->rt_gateway);
 584         getmicrotime(&timenow);
 585         if ((route->rt_rmx.rmx_expire == 0 || route->rt_rmx.rmx_expire > timenow.tv_sec) &&
 586                 gateway != NULL && gateway->sdl_family == AF_LINK && gateway->sdl_alen != 0) {
 587                 bcopy(gateway, ll_dest, MIN(gateway->sdl_len, ll_dest_len));
 588                 lck_mtx_unlock(rt_mtx);
 589                 return 0;
 590         }
 591
 592         /*
 593          * Route wasn't complete/valid. We need to arp.
 594          */
 595         if (ifp->if_flags & IFF_NOARP) {
 596                 lck_mtx_unlock(rt_mtx);
 597                 return ENOTSUP;
 598         }
 599
 600         llinfo = (struct llinfo_arp*)route->rt_llinfo;
 601         if (packet) {
 602                 if (llinfo->la_hold) {
 603                         m_freem(llinfo->la_hold);
 604                 }
 605                 llinfo->la_hold = packet;
 606         }
 607
 608         if (route->rt_rmx.rmx_expire) {
 609                 route->rt_flags &= ~RTF_REJECT;
 610                 if (llinfo->la_asked == 0 || route->rt_rmx.rmx_expire != timenow.tv_sec) {
 611                         route->rt_rmx.rmx_expire = timenow.tv_sec;
 612                         if (llinfo->la_asked++ < arp_maxtries) {
 613                                 lck_mtx_unlock(rt_mtx);
 614                                 dlil_send_arp(ifp, ARPOP_REQUEST, NULL, route->rt_ifa->ifa_addr,
 615                                                           NULL, (const struct sockaddr*)net_dest);
 616                                 return EJUSTRETURN;
 617                         }
 618                         else {
 619                                 route->rt_flags |= RTF_REJECT;
 620                                 route->rt_rmx.rmx_expire += arpt_down;
 621                                 llinfo->la_asked = 0;
 622                                 llinfo->la_hold = NULL;
 623                                 lck_mtx_unlock(rt_mtx);
 624                                 return EHOSTUNREACH;
 625                         }
 626                 }
 627         }
 628         lck_mtx_unlock(rt_mtx);
 629
 630         return EJUSTRETURN;
 631 }
 632
 633 errno_t
 634 arp_ip_handle_input(
 635         ifnet_t         ifp,
 636         u_short         arpop,
 637         const struct sockaddr_dl *sender_hw,
 638         const struct sockaddr_in *sender_ip,
 639         const struct sockaddr_in *target_ip)
 640 {
 641         char    ipv4str[MAX_IPv4_STR_LEN];
 642         struct sockaddr_dl *gateway;
 643         struct in_ifaddr *ia;
 644         struct in_ifaddr *best_ia = NULL;
 645         route_t route = NULL;
 646         char buf[3 * MAX_HW_LEN]; // enough for MAX_HW_LEN byte hw address
 647         struct llinfo_arp *llinfo;
 648         errno_t error;
 649         int created_announcement = 0;
 650
 651         /* Do not respond to requests for 0.0.0.0 */
 652         if (target_ip->sin_addr.s_addr == 0 && arpop == ARPOP_REQUEST) {
 653                 return 0;
 654         }
 655
 656         /*
 657          * Determine if this ARP is for us
 658          */
 659         lck_mtx_lock(rt_mtx);
 660         for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
 661                 /* do_bridge should be tested here for bridging */
 662                 if (ia->ia_ifp == ifp) {
 663                         best_ia = ia;
 664                         if (target_ip->sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr ||
 665                                 sender_ip->sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr) {
 666                                 break;
 667                         }
 668                 }
 669         }
 670
 671         /* If we don't have an IP address on this interface, ignore the packet */
 672         if (best_ia == 0) {
 673                 lck_mtx_unlock(rt_mtx);
 674                 return 0;
 675         }
 676
 677         /* If the packet is from this interface, ignore the packet */
 678         if (!bcmp(CONST_LLADDR(sender_hw), ifnet_lladdr(ifp), sender_hw->sdl_len)) {
 679                 lck_mtx_unlock(rt_mtx);
 680                 return 0;
 681         }
 682
 683         /* Check for a conflict */
 684         if (sender_ip->sin_addr.s_addr == best_ia->ia_addr.sin_addr.s_addr) {
 685                 struct kev_msg        ev_msg;
 686                 struct kev_in_collision *in_collision;
 687                 u_char  storage[sizeof(struct kev_in_collision) + MAX_HW_LEN];
 688                 in_collision = (struct kev_in_collision*)storage;
 689                 log(LOG_ERR, "%s%d duplicate IP address %s sent from address %s\n",
 690                         ifp->if_name, ifp->if_unit,
 691                         inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str, sizeof(ipv4str)),
 692                         sdl_addr_to_hex(sender_hw, buf, sizeof(buf)));
 693
 694                 /* Send a kernel event so anyone can learn of the conflict */
 695                 in_collision->link_data.if_family = ifp->if_family;
 696                 in_collision->link_data.if_unit = ifp->if_unit;
 697                 strncpy(&in_collision->link_data.if_name[0], ifp->if_name, IFNAMSIZ);
 698                 in_collision->ia_ipaddr = sender_ip->sin_addr;
 699                 in_collision->hw_len = sender_hw->sdl_alen < MAX_HW_LEN ? sender_hw->sdl_alen : MAX_HW_LEN;
 700                 bcopy(CONST_LLADDR(sender_hw), (caddr_t)in_collision->hw_addr, in_collision->hw_len);
 701                 ev_msg.vendor_code = KEV_VENDOR_APPLE;
 702                 ev_msg.kev_class = KEV_NETWORK_CLASS;
 703                 ev_msg.kev_subclass = KEV_INET_SUBCLASS;
 704                 ev_msg.event_code = KEV_INET_ARPCOLLISION;
 705                 ev_msg.dv[0].data_ptr = in_collision;
 706                 ev_msg.dv[0].data_length = sizeof(struct kev_in_collision) + in_collision->hw_len;
 707                 ev_msg.dv[1].data_length = 0;
 708                 kev_post_msg(&ev_msg);
 709
 710                 goto respond;
 711         }
 712
 713         /*
 714          * Look up the routing entry. If it doesn't exist and we are the
 715          * target, and the sender isn't 0.0.0.0, go ahead and create one.
 716          */
 717         error = arp_lookup_route(&sender_ip->sin_addr,
 718             (target_ip->sin_addr.s_addr == best_ia->ia_addr.sin_addr.s_addr &&
 719             sender_ip->sin_addr.s_addr != 0), 0, &route, ifp->if_index);
 720         if (error || route == 0 || route->rt_gateway == 0) {
 721                 if (arpop != ARPOP_REQUEST) {
 722                         goto respond;
 723                 }
 724                 if (arp_sendllconflict
 725                     && send_conflicting_probes != 0
 726                     && (ifp->if_eflags & IFEF_ARPLL) != 0
 727                     && IN_LINKLOCAL(ntohl(target_ip->sin_addr.s_addr))
 728                     && sender_ip->sin_addr.s_addr == 0) {
 729                         /*
 730                          * Verify this ARP probe doesn't conflict with an IPv4LL we know of
 731                          * on another interface.
 732                          */
 733                         error = arp_lookup_route(&target_ip->sin_addr, 0, 0,
 734                             &route, ifp->if_index);
 735                         if (error == 0 && route && route->rt_gateway) {
 736                                 gateway = SDL(route->rt_gateway);
 737                                 if (route->rt_ifp != ifp && gateway->sdl_alen != 0
 738                                     && (gateway->sdl_alen != sender_hw->sdl_alen
 739                                         || bcmp(CONST_LLADDR(gateway), CONST_LLADDR(sender_hw),
 740                                                 gateway->sdl_alen) != 0)) {
 741                                         /*
 742                                          * A node is probing for an IPv4LL we know exists on a
 743                                          * different interface. We respond with a conflicting probe
 744                                          * to force the new device to pick a different IPv4LL
 745                                          * address.
 746                                          */
 747                                         if (log_arp_warnings) {
 748                                             log(LOG_INFO,
 749                                                 "arp: %s on %s%d sent probe for %s, already on %s%d\n",
 750                                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 751                                                 ifp->if_name, ifp->if_unit,
 752                                                 inet_ntop(AF_INET, &target_ip->sin_addr, ipv4str,
 753                                                                   sizeof(ipv4str)),
 754                                                 route->rt_ifp->if_name, route->rt_ifp->if_unit);
 755                                             log(LOG_INFO,
 756                                                 "arp: sending conflicting probe to %s on %s%d\n",
 757                                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 758                                                 ifp->if_name, ifp->if_unit);
 759                                         }
 760                                         /*
 761                                          * Send a conservative unicast "ARP probe".
 762                                          * This should force the other device to pick a new number.
 763                                          * This will not force the device to pick a new number if the device
 764                                          * has already assigned that number.
 765                                          * This will not imply to the device that we own that address.
 766                                          */
 767                                         dlil_send_arp_internal(ifp, ARPOP_REQUEST,
 768                                                 (struct sockaddr_dl*)TAILQ_FIRST(&ifp->if_addrhead)->ifa_addr,
 769                                                 (const struct sockaddr*)sender_ip, sender_hw,
 770                                                 (const struct sockaddr*)target_ip);
 771                                 }
 772                         }
 773                         goto respond;
 774                 } else if (keep_announcements != 0
 775                            && target_ip->sin_addr.s_addr == sender_ip->sin_addr.s_addr) {
 776                         /* don't create entry if link-local address and link-local is disabled */
 777                         if (!IN_LINKLOCAL(ntohl(sender_ip->sin_addr.s_addr))
 778                             || (ifp->if_eflags & IFEF_ARPLL) != 0) {
 779                                 error = arp_lookup_route(&sender_ip->sin_addr,
 780                                     1, 0, &route, ifp->if_index);
 781                                 if (error == 0 && route != NULL && route->rt_gateway != NULL) {
 782                                         created_announcement = 1;
 783                                 }
 784                         }
 785                         if (created_announcement == 0) {
 786                                 goto respond;
 787                         }
 788                 } else {
 789                         goto respond;
 790                 }
 791         }
 792
 793         gateway = SDL(route->rt_gateway);
 794         if (route->rt_ifp != ifp) {
 795                 if (!IN_LINKLOCAL(ntohl(sender_ip->sin_addr.s_addr)) || (ifp->if_eflags & IFEF_ARPLL) == 0) {
 796                         if (log_arp_warnings)
 797                                 log(LOG_ERR, "arp: %s is on %s%d but got reply from %s on %s%d\n",
 798                                         inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 799                                                           sizeof(ipv4str)),
 800                                         route->rt_ifp->if_name,
 801                                         route->rt_ifp->if_unit,
 802                                         sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 803                                         ifp->if_name, ifp->if_unit);
 804                         goto respond;
 805                 }
 806                 else {
 807                         /* Don't change a permanent address */
 808                         if (route->rt_rmx.rmx_expire == 0) {
 809                                 goto respond;
 810                         }
 811
 812                         /*
 813                          * Don't change the cloned route away from the parent's interface
 814                          * if the address did resolve.
 815                          */
 816                         if (gateway->sdl_alen != 0 && route->rt_parent &&
 817                                 route->rt_parent->rt_ifp == route->rt_ifp) {
 818                                 goto respond;
 819                         }
 820
 821                         /* Change the interface when the existing route is on */
 822                         route->rt_ifp = ifp;
 823                         rtsetifa(route, &best_ia->ia_ifa);
 824                         gateway->sdl_index = ifp->if_index;
 825                 }
 826         }
 827
 828         if (gateway->sdl_alen && bcmp(LLADDR(gateway), CONST_LLADDR(sender_hw), gateway->sdl_alen)) {
 829                 if (route->rt_rmx.rmx_expire && log_arp_warnings) {
 830                         char buf2[3 * MAX_HW_LEN];
 831                         log(LOG_INFO, "arp: %s moved from %s to %s on %s%d\n",
 832                             inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 833                             sizeof(ipv4str)),
 834                             sdl_addr_to_hex(gateway, buf, sizeof(buf)),
 835                             sdl_addr_to_hex(sender_hw, buf2, sizeof(buf2)),
 836                             ifp->if_name, ifp->if_unit);
 837                 }
 838                 else if (route->rt_rmx.rmx_expire == 0) {
 839                         if (log_arp_warnings) {
 840                                 log(LOG_ERR, "arp: %s attempts to modify "
 841                                     "permanent entry for %s on %s%d\n",
 842                                     sdl_addr_to_hex(sender_hw, buf,
 843                                     sizeof(buf)),
 844                                     inet_ntop(AF_INET, &sender_ip->sin_addr,
 845                                     ipv4str, sizeof(ipv4str)),
 846                                     ifp->if_name, ifp->if_unit);
 847                         }
 848                         goto respond;
 849                 }
 850         }
 851
 852         /* Copy the sender hardware address in to the route's gateway address */
 853         gateway->sdl_alen = sender_hw->sdl_alen;
 854         bcopy(CONST_LLADDR(sender_hw), LLADDR(gateway), gateway->sdl_alen);
 855
 856         /* Update the expire time for the route and clear the reject flag */
 857         if (route->rt_rmx.rmx_expire) {
 858                 struct timeval timenow;
 859
 860                 getmicrotime(&timenow);
 861                 route->rt_rmx.rmx_expire = timenow.tv_sec + arpt_keep;
 862         }
 863         route->rt_flags &= ~RTF_REJECT;
 864
 865         /* update the llinfo, send a queued packet if there is one */
 866         llinfo = (struct llinfo_arp*)route->rt_llinfo;
 867         llinfo->la_asked = 0;
 868         if (llinfo->la_hold) {
 869                 struct mbuf *m0;
 870                 m0 = llinfo->la_hold;
 871                 llinfo->la_hold = 0;
 872
 873                 /* Should we a reference on the route first? */
 874                 lck_mtx_unlock(rt_mtx);
 875                 dlil_output(ifp, PF_INET, m0, (caddr_t)route, rt_key(route), 0);
 876                 lck_mtx_lock(rt_mtx);
 877         }
 878
 879 respond:
 880         if (arpop != ARPOP_REQUEST) {
 881                 lck_mtx_unlock(rt_mtx);
 882                 return 0;
 883         }
 884
 885         /* If we are not the target, check if we should proxy */
 886         if (target_ip->sin_addr.s_addr != best_ia->ia_addr.sin_addr.s_addr) {
 887
 888                 /* Find a proxy route */
 889                 error = arp_lookup_route(&target_ip->sin_addr, 0, SIN_PROXY,
 890                     &route, ifp->if_index);
 891                 if (error || route == NULL) {
 892
 893                         /* We don't have a route entry indicating we should use proxy */
 894                         /* If we aren't supposed to proxy all, we are done */
 895                         if (!arp_proxyall) {
 896                                 lck_mtx_unlock(rt_mtx);
 897                                 return 0;
 898                         }
 899
 900                         /* See if we have a route to the target ip before we proxy it */
 901                         route = rtalloc1_scoped_locked(
 902                             (const struct sockaddr *)target_ip, 0, 0,
 903                             ifp->if_index);
 904                         if (!route) {
 905                                 lck_mtx_unlock(rt_mtx);
 906                                 return 0;
 907                         }
 908
 909                         /*
 910                          * Don't proxy for hosts already on the same interface.
 911                          */
 912                         if (route->rt_ifp == ifp) {
 913                                 rtfree_locked(route);
 914                                 lck_mtx_unlock(rt_mtx);
 915                                 return 0;
 916                         }
 917                 }
 918         }
 919         lck_mtx_unlock(rt_mtx);
 920
 921         dlil_send_arp(ifp, ARPOP_REPLY, NULL, (const struct sockaddr*)target_ip,
 922                 sender_hw, (const struct sockaddr*)sender_ip);
 923
 924         return 0;
 925 }
 926
 927 void
 928 arp_ifinit(
 929         struct ifnet *ifp,
 930         struct ifaddr *ifa)
 931 {
 932         ifa->ifa_rtrequest = arp_rtrequest;
 933         ifa->ifa_flags |= RTF_CLONING;
 934         dlil_send_arp(ifp, ARPOP_REQUEST, NULL, ifa->ifa_addr, NULL, ifa->ifa_addr);
 935 }