bsd/netinet/in_arp.c

   1 /*
   2  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1982, 1989, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  *
  54  */
  55
  56 #include <kern/debug.h>
  57 #include <netinet/in_arp.h>
  58 #include <sys/types.h>
  59 #include <sys/param.h>
  60 #include <sys/kernel_types.h>
  61 #include <sys/syslog.h>
  62 #include <sys/systm.h>
  63 #include <sys/time.h>
  64 #include <sys/kernel.h>
  65 #include <sys/mbuf.h>
  66 #include <sys/sysctl.h>
  67 #include <string.h>
  68 #include <net/if_arp.h>
  69 #include <net/if_dl.h>
  70 #include <net/dlil.h>
  71 #include <net/route.h>
  72 #include <netinet/if_ether.h>
  73 #include <netinet/in_var.h>
  74
  75 #define SIN(s) ((struct sockaddr_in *)s)
  76 #define CONST_LLADDR(s) ((const u_char*)((s)->sdl_data + (s)->sdl_nlen))
  77 #define rt_expire rt_rmx.rmx_expire
  78
  79 static const size_t MAX_HW_LEN = 10;
  80
  81 SYSCTL_DECL(_net_link_ether);
  82 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
  83
  84 /* timer values */
  85 static int arpt_prune = (5*60*1); /* walk list every 5 minutes */
  86 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
  87 static int arpt_down = 20;      /* once declared down, don't send for 20 sec */
  88
  89 /* Apple Hardware SUM16 checksuming */
  90 int apple_hwcksum_tx = 1;
  91 int apple_hwcksum_rx = 1;
  92
  93 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW,
  94            &arpt_prune, 0, "");
  95 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  96            &arpt_keep, 0, "");
  97 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, host_down_time, CTLFLAG_RW,
  98            &arpt_down, 0, "");
  99 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, apple_hwcksum_tx, CTLFLAG_RW,
 100            &apple_hwcksum_tx, 0, "");
 101 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, apple_hwcksum_rx, CTLFLAG_RW,
 102            &apple_hwcksum_rx, 0, "");
 103
 104 struct llinfo_arp {
 105         LIST_ENTRY(llinfo_arp) la_le;
 106         struct  rtentry *la_rt;
 107         struct  mbuf *la_hold;          /* last packet until resolved/timeout */
 108         long    la_asked;               /* last time we QUERIED for this addr */
 109 };
 110
 111 static LIST_HEAD(, llinfo_arp) llinfo_arp;
 112
 113 static int      arp_inuse, arp_allocated;
 114
 115 static int      arp_maxtries = 5;
 116 static int      useloopback = 1; /* use loopback interface for local traffic */
 117 static int      arp_proxyall = 0;
 118
 119 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
 120            &arp_maxtries, 0, "");
 121 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
 122            &useloopback, 0, "");
 123 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
 124            &arp_proxyall, 0, "");
 125
 126 static int log_arp_warnings = 0;
 127
 128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_warnings, CTLFLAG_RW,
 129         &log_arp_warnings, 0,
 130         "log arp warning messages");
 131
 132 extern u_int32_t        ipv4_ll_arp_aware;
 133
 134 /*
 135  * Free an arp entry.
 136  */
 137 static void
 138 arptfree(
 139         struct llinfo_arp *la)
 140 {
 141         struct rtentry *rt = la->la_rt;
 142         struct sockaddr_dl *sdl;
 143         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 144         if (rt == 0)
 145                 panic("arptfree");
 146         if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) &&
 147             sdl->sdl_family == AF_LINK) {
 148                 sdl->sdl_alen = 0;
 149                 la->la_asked = 0;
 150                 rt->rt_flags &= ~RTF_REJECT;
 151                 return;
 152         }
 153         rtrequest_locked(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt),
 154                         0, (struct rtentry **)0);
 155 }
 156
 157 /*
 158  * Timeout routine.  Age arp_tab entries periodically.
 159  */
 160 /* ARGSUSED */
 161 static void
 162 arptimer(
 163         __unused void *ignored_arg)
 164 {
 165         struct llinfo_arp *la = llinfo_arp.lh_first;
 166         struct llinfo_arp *ola;
 167         struct timeval timenow;
 168
 169         lck_mtx_lock(rt_mtx);
 170         getmicrotime(&timenow);
 171         while ((ola = la) != 0) {
 172                 struct rtentry *rt = la->la_rt;
 173                 la = la->la_le.le_next;
 174                 if (rt->rt_expire && rt->rt_expire <= timenow.tv_sec)
 175                         arptfree(ola); /* timer has expired, clear */
 176         }
 177         lck_mtx_unlock(rt_mtx);
 178         timeout(arptimer, (caddr_t)0, arpt_prune * hz);
 179 }
 180
 181 /*
 182  * Parallel to llc_rtrequest.
 183  */
 184 static void
 185 arp_rtrequest(
 186         int req,
 187         struct rtentry *rt,
 188         __unused struct sockaddr *sa)
 189 {
 190         struct sockaddr *gate = rt->rt_gateway;
 191         struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
 192         static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK, 0, 0, 0, 0, 0, {0}};
 193         static int arpinit_done;
 194         struct timeval timenow;
 195
 196         if (!arpinit_done) {
 197                 arpinit_done = 1;
 198                 LIST_INIT(&llinfo_arp);
 199                 timeout(arptimer, (caddr_t)0, hz);
 200         }
 201         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 202
 203         if (rt->rt_flags & RTF_GATEWAY)
 204                 return;
 205         getmicrotime(&timenow);
 206         switch (req) {
 207
 208         case RTM_ADD:
 209                 /*
 210                  * XXX: If this is a manually added route to interface
 211                  * such as older version of routed or gated might provide,
 212                  * restore cloning bit.
 213                  */
 214                 if ((rt->rt_flags & RTF_HOST) == 0 &&
 215                     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
 216                         rt->rt_flags |= RTF_CLONING;
 217                 if (rt->rt_flags & RTF_CLONING) {
 218                         /*
 219                          * Case 1: This route should come from a route to iface.
 220                          */
 221                         rt_setgate(rt, rt_key(rt),
 222                                         (struct sockaddr *)&null_sdl);
 223                         gate = rt->rt_gateway;
 224                         SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 225                         SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 226                         rt->rt_expire = timenow.tv_sec;
 227                         break;
 228                 }
 229                 /* Announce a new entry if requested. */
 230                 if (rt->rt_flags & RTF_ANNOUNCE)
 231                         dlil_send_arp(rt->rt_ifp, ARPOP_REQUEST, SDL(gate), rt_key(rt), (struct sockaddr_dl *)rt_key(rt), NULL);
 232                 /*FALLTHROUGH*/
 233         case RTM_RESOLVE:
 234                 if (gate->sa_family != AF_LINK ||
 235                     gate->sa_len < sizeof(null_sdl)) {
 236                         if (log_arp_warnings)
 237                                 log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
 238                         break;
 239                 }
 240                 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 241                 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 242                 if (la != 0)
 243                         break; /* This happens on a route change */
 244                 /*
 245                  * Case 2:  This route may come from cloning, or a manual route
 246                  * add with a LL address.
 247                  */
 248                 R_Malloc(la, struct llinfo_arp *, sizeof(*la));
 249                 rt->rt_llinfo = (caddr_t)la;
 250                 if (la == 0) {
 251                         if ( log_arp_warnings)
 252                                 log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
 253                         break;
 254                 }
 255                 arp_inuse++, arp_allocated++;
 256                 Bzero(la, sizeof(*la));
 257                 la->la_rt = rt;
 258                 rt->rt_flags |= RTF_LLINFO;
 259                 LIST_INSERT_HEAD(&llinfo_arp, la, la_le);
 260
 261 #if INET
 262                 /*
 263                  * This keeps the multicast addresses from showing up
 264                  * in `arp -a' listings as unresolved.  It's not actually
 265                  * functional.  Then the same for broadcast.
 266                  */
 267                 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr))) {
 268                         dlil_resolve_multi(rt->rt_ifp, rt_key(rt), gate, sizeof(struct sockaddr_dl));
 269                         rt->rt_expire = 0;
 270                 }
 271                 else if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
 272                         struct sockaddr_dl      *gate_ll = SDL(gate);
 273                         size_t  broadcast_len;
 274                         ifnet_llbroadcast_copy_bytes(rt->rt_ifp, LLADDR(gate_ll),
 275                                                                                  sizeof(gate_ll->sdl_data),
 276                                                                                  &broadcast_len);
 277                         gate_ll->sdl_alen = broadcast_len;
 278                         gate_ll->sdl_family = AF_LINK;
 279                         gate_ll->sdl_len = sizeof(struct sockaddr_dl);
 280                         rt->rt_expire = timenow.tv_sec;
 281                 }
 282 #endif
 283
 284                 if (SIN(rt_key(rt))->sin_addr.s_addr ==
 285                     (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) {
 286                     /*
 287                      * This test used to be
 288                      *  if (loif.if_flags & IFF_UP)
 289                      * It allowed local traffic to be forced
 290                      * through the hardware by configuring the loopback down.
 291                      * However, it causes problems during network configuration
 292                      * for boards that can't receive packets they send.
 293                      * It is now necessary to clear "useloopback" and remove
 294                      * the route to force traffic out to the hardware.
 295                      */
 296                         rt->rt_expire = 0;
 297                         ifnet_lladdr_copy_bytes(rt->rt_ifp, LLADDR(SDL(gate)), SDL(gate)->sdl_alen = 6);
 298                         if (useloopback)
 299                                 rt->rt_ifp = loif;
 300
 301                 }
 302                 break;
 303
 304         case RTM_DELETE:
 305                 if (la == 0)
 306                         break;
 307                 arp_inuse--;
 308                 LIST_REMOVE(la, la_le);
 309                 rt->rt_llinfo = 0;
 310                 rt->rt_flags &= ~RTF_LLINFO;
 311                 if (la->la_hold) {
 312                         m_freem(la->la_hold);
 313                 }
 314                 la->la_hold = NULL;
 315                 R_Free((caddr_t)la);
 316         }
 317 }
 318
 319 /*
 320  * convert hardware address to hex string for logging errors.
 321  */
 322 static const char *
 323 sdl_addr_to_hex(const struct sockaddr_dl *sdl, char * orig_buf, int buflen)
 324 {
 325         char *          buf = orig_buf;
 326         int             i;
 327         const u_char *  lladdr = sdl->sdl_data;
 328         int                     maxbytes = buflen / 3;
 329
 330         if (maxbytes > sdl->sdl_alen) {
 331                 maxbytes = sdl->sdl_alen;
 332         }
 333         *buf = '\0';
 334         for (i = 0; i < maxbytes; i++) {
 335                 snprintf(buf, 3, "%02x", lladdr[i]);
 336                 buf += 2;
 337                 *buf = (i == maxbytes - 1) ? '\0' : ':';
 338                 buf++;
 339         }
 340         return (orig_buf);
 341 }
 342
 343 /*
 344  * arp_lookup_route will lookup the route for a given address.
 345  *
 346  * The routing lock must be held. The address must be for a
 347  * host on a local network on this interface.
 348  */
 349 static errno_t
 350 arp_lookup_route(
 351         const struct in_addr *addr,
 352         int     create,
 353         int proxy,
 354         route_t *route)
 355 {
 356         struct sockaddr_inarp sin = {sizeof(sin), AF_INET, 0, {0}, {0}, 0, 0};
 357         const char *why = 0;
 358         errno_t error = 0;
 359
 360         // Caller is responsible for taking the routing lock
 361         lck_mtx_assert(rt_mtx, LCK_MTX_ASSERT_OWNED);
 362
 363         sin.sin_addr.s_addr = addr->s_addr;
 364         sin.sin_other = proxy ? SIN_PROXY : 0;
 365
 366         *route = rtalloc1_locked((const struct sockaddr*)&sin, create, 0);
 367         if (*route == NULL)
 368                 return ENETUNREACH;
 369
 370         rtunref(*route);
 371
 372         if ((*route)->rt_flags & RTF_GATEWAY) {
 373                 why = "host is not on local network";
 374
 375                 /* If there are no references to this route, purge it */
 376                 if ((*route)->rt_refcnt <= 0 && ((*route)->rt_flags & RTF_WASCLONED) != 0) {
 377                         rtrequest_locked(RTM_DELETE,
 378                                         (struct sockaddr *)rt_key(*route),
 379                                         (*route)->rt_gateway, rt_mask(*route),
 380                                         (*route)->rt_flags, 0);
 381                 }
 382                 *route = NULL;
 383                 error = ENETUNREACH;
 384         }
 385         else if (((*route)->rt_flags & RTF_LLINFO) == 0) {
 386                 why = "could not allocate llinfo";
 387                 *route = NULL;
 388                 error = ENOMEM;
 389         }
 390         else if ((*route)->rt_gateway->sa_family != AF_LINK) {
 391                 why = "gateway route is not ours";
 392                 *route = NULL;
 393                 error = EPROTONOSUPPORT;
 394         }
 395
 396         if (why && create && log_arp_warnings) {
 397                 char    tmp[MAX_IPv4_STR_LEN];
 398                 log(LOG_DEBUG, "arplookup %s failed: %s\n",
 399                         inet_ntop(AF_INET, addr, tmp, sizeof(tmp)), why);
 400         }
 401
 402         return error;
 403 }
 404
 405
 406 __private_extern__ errno_t
 407 arp_route_to_gateway_route(
 408         const struct sockaddr *net_dest,
 409         route_t hint,
 410         route_t *out_route);
 411 /*
 412  * arp_route_to_gateway_route will find the gateway route for a given route.
 413  *
 414  * If the route is down, look the route up again.
 415  * If the route goes through a gateway, get the route to the gateway.
 416  * If the gateway route is down, look it up again.
 417  * If the route is set to reject, verify it hasn't expired.
 418  */
 419 __private_extern__ errno_t
 420 arp_route_to_gateway_route(
 421         const struct sockaddr *net_dest,
 422         route_t hint,
 423         route_t *out_route)
 424 {
 425         route_t route = hint;
 426         *out_route = NULL;
 427         struct timeval timenow;
 428
 429         /* If we got a hint from the higher layers, check it out */
 430         if (route) {
 431                 lck_mtx_lock(rt_mtx);
 432
 433                 if ((route->rt_flags & RTF_UP) == 0) {
 434                         /* route is down, find a new one */
 435                         hint = route = rtalloc1_locked(net_dest, 1, 0);
 436                         if (hint) {
 437                                 rtunref(hint);
 438                         }
 439                         else {
 440                                 /* No route to host */
 441                                 lck_mtx_unlock(rt_mtx);
 442                                 return EHOSTUNREACH;
 443                         }
 444                 }
 445
 446                 if (route->rt_flags & RTF_GATEWAY) {
 447                         /*
 448                          * We need the gateway route. If it is NULL or down,
 449                          * look it up.
 450                          */
 451                         if (route->rt_gwroute == 0 ||
 452                                 (route->rt_gwroute->rt_flags & RTF_UP) == 0) {
 453                                 if (route->rt_gwroute != 0)
 454                                         rtfree_locked(route->rt_gwroute);
 455
 456                                 route->rt_gwroute = rtalloc1_locked(route->rt_gateway, 1, 0);
 457                                 if (route->rt_gwroute == 0) {
 458                                         lck_mtx_unlock(rt_mtx);
 459                                         return EHOSTUNREACH;
 460                                 }
 461                         }
 462
 463                         route = route->rt_gwroute;
 464                 }
 465
 466                 if (route->rt_flags & RTF_REJECT) {
 467                         getmicrotime(&timenow);
 468                         if (route->rt_rmx.rmx_expire == 0 ||
 469                                 timenow.tv_sec < route->rt_rmx.rmx_expire) {
 470                                 lck_mtx_unlock(rt_mtx);
 471                                 return route == hint ? EHOSTDOWN : EHOSTUNREACH;
 472                         }
 473                 }
 474
 475                 lck_mtx_unlock(rt_mtx);
 476         }
 477
 478         *out_route = route;
 479         return 0;
 480 }
 481
 482 errno_t
 483 arp_lookup_ip(
 484         ifnet_t ifp,
 485         const struct sockaddr_in *net_dest,
 486         struct sockaddr_dl *ll_dest,
 487         size_t  ll_dest_len,
 488         route_t hint,
 489         mbuf_t packet)
 490 {
 491         route_t route = NULL;
 492         errno_t result = 0;
 493         struct sockaddr_dl      *gateway;
 494         struct llinfo_arp       *llinfo;
 495         struct timeval timenow;
 496
 497         if (net_dest->sin_family != AF_INET)
 498                 return EAFNOSUPPORT;
 499
 500         if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 501                 return ENETDOWN;
 502
 503         /*
 504          * If we were given a route, verify the route and grab the gateway
 505          */
 506         if (hint) {
 507                 result = arp_route_to_gateway_route((const struct sockaddr*)net_dest,
 508                                                                                         hint, &route);
 509                 if (result != 0)
 510                         return result;
 511         }
 512
 513         if (packet->m_flags & M_BCAST) {
 514                 u_long  broadcast_len;
 515                 bzero(ll_dest, ll_dest_len);
 516                 result = ifnet_llbroadcast_copy_bytes(ifp, LLADDR(ll_dest), ll_dest_len
 517                                                                                           - offsetof(struct sockaddr_dl,
 518                                                                                           sdl_data), &broadcast_len);
 519                 if (result != 0) {
 520                         return result;
 521                 }
 522
 523                 ll_dest->sdl_alen = broadcast_len;
 524                 ll_dest->sdl_family = AF_LINK;
 525                 ll_dest->sdl_len = sizeof(struct sockaddr_dl);
 526
 527                 return 0;
 528         }
 529         if (packet->m_flags & M_MCAST) {
 530                 return dlil_resolve_multi(ifp, (const struct sockaddr*)net_dest,
 531                                                                    (struct sockaddr*)ll_dest, ll_dest_len);
 532         }
 533
 534         lck_mtx_lock(rt_mtx);
 535
 536         /*
 537          * If we didn't find a route, or the route doesn't have
 538          * link layer information, trigger the creation of the
 539          * route and link layer information.
 540          */
 541         if (route == NULL || route->rt_llinfo == NULL)
 542                 result = arp_lookup_route(&net_dest->sin_addr, 1, 0, &route);
 543
 544         if (result || route == NULL || route->rt_llinfo == NULL) {
 545                 char    tmp[MAX_IPv4_STR_LEN];
 546                 lck_mtx_unlock(rt_mtx);
 547                 if (log_arp_warnings)
 548                         log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s\n",
 549                                 inet_ntop(AF_INET, &net_dest->sin_addr, tmp, sizeof(tmp)));
 550                 return result;
 551         }
 552
 553         /*
 554          * Now that we have the right route, is it filled in?
 555          */
 556         gateway = SDL(route->rt_gateway);
 557         getmicrotime(&timenow);
 558         if ((route->rt_rmx.rmx_expire == 0 || route->rt_rmx.rmx_expire > timenow.tv_sec) &&
 559                 gateway != NULL && gateway->sdl_family == AF_LINK && gateway->sdl_alen != 0) {
 560                 bcopy(gateway, ll_dest, MIN(gateway->sdl_len, ll_dest_len));
 561                 lck_mtx_unlock(rt_mtx);
 562                 return 0;
 563         }
 564
 565         /*
 566          * Route wasn't complete/valid. We need to arp.
 567          */
 568         if (ifp->if_flags & IFF_NOARP) {
 569                 lck_mtx_unlock(rt_mtx);
 570                 return ENOTSUP;
 571         }
 572
 573         llinfo = (struct llinfo_arp*)route->rt_llinfo;
 574         if (packet) {
 575                 if (llinfo->la_hold) {
 576                         m_freem(llinfo->la_hold);
 577                 }
 578                 llinfo->la_hold = packet;
 579         }
 580
 581         if (route->rt_rmx.rmx_expire) {
 582                 route->rt_flags &= ~RTF_REJECT;
 583                 if (llinfo->la_asked == 0 || route->rt_rmx.rmx_expire != timenow.tv_sec) {
 584                         route->rt_rmx.rmx_expire = timenow.tv_sec;
 585                         if (llinfo->la_asked++ < arp_maxtries) {
 586                                 lck_mtx_unlock(rt_mtx);
 587                                 dlil_send_arp(ifp, ARPOP_REQUEST, NULL, route->rt_ifa->ifa_addr,
 588                                                           NULL, (const struct sockaddr*)net_dest);
 589                                 return EJUSTRETURN;
 590                         }
 591                         else {
 592                                 route->rt_flags |= RTF_REJECT;
 593                                 route->rt_rmx.rmx_expire += arpt_down;
 594                                 llinfo->la_asked = 0;
 595                                 llinfo->la_hold = 0;
 596                                 lck_mtx_unlock(rt_mtx);
 597                                 return EHOSTUNREACH;
 598                         }
 599                 }
 600         }
 601         lck_mtx_unlock(rt_mtx);
 602
 603         return EJUSTRETURN;
 604 }
 605
 606 errno_t
 607 arp_ip_handle_input(
 608         ifnet_t         ifp,
 609         u_short         arpop,
 610         const struct sockaddr_dl *sender_hw,
 611         const struct sockaddr_in *sender_ip,
 612         const struct sockaddr_in *target_ip)
 613 {
 614         char    ipv4str[MAX_IPv4_STR_LEN];
 615         struct sockaddr_dl *gateway;
 616         struct in_ifaddr *ia;
 617         struct in_ifaddr *best_ia = NULL;
 618         route_t route = NULL;
 619         char buf[3 * MAX_HW_LEN]; // enough for MAX_HW_LEN byte hw address
 620         struct llinfo_arp *llinfo;
 621         struct timeval timenow;
 622         errno_t error;
 623
 624         /* Do not respond to requests for 0.0.0.0 */
 625         if (target_ip->sin_addr.s_addr == 0 && arpop == ARPOP_REQUEST) {
 626                 return 0;
 627         }
 628
 629         /*
 630          * Determine if this ARP is for us
 631          */
 632         lck_mtx_lock(rt_mtx);
 633         for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
 634                 /* do_bridge should be tested here for bridging */
 635                 if (ia->ia_ifp == ifp) {
 636                         best_ia = ia;
 637                         if (target_ip->sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr ||
 638                                 sender_ip->sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr) {
 639                                 break;
 640                         }
 641                 }
 642         }
 643
 644         /* If we don't have an IP address on this interface, ignore the packet */
 645         if (best_ia == 0) {
 646                 lck_mtx_unlock(rt_mtx);
 647                 return 0;
 648         }
 649
 650         /* If the packet is from this interface, ignore the packet */
 651         if (!bcmp(CONST_LLADDR(sender_hw), ifnet_lladdr(ifp), sender_hw->sdl_len)) {
 652                 lck_mtx_unlock(rt_mtx);
 653                 return 0;
 654         }
 655
 656         /* Check for a conflict */
 657         if (sender_ip->sin_addr.s_addr == best_ia->ia_addr.sin_addr.s_addr) {
 658                 struct kev_msg        ev_msg;
 659                 struct kev_in_collision *in_collision;
 660                 u_char  storage[sizeof(struct kev_in_collision) + MAX_HW_LEN];
 661                 in_collision = (struct kev_in_collision*)storage;
 662                 log(LOG_ERR, "%s%d duplicate IP address %s sent from address %s\n",
 663                         ifp->if_name, ifp->if_unit,
 664                         inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str, sizeof(ipv4str)),
 665                         sdl_addr_to_hex(sender_hw, buf, sizeof(buf)));
 666
 667                 /* Send a kernel event so anyone can learn of the conflict */
 668                 in_collision->link_data.if_family = ifp->if_family;
 669                 in_collision->link_data.if_unit = ifp->if_unit;
 670                 strncpy(&in_collision->link_data.if_name[0], ifp->if_name, IFNAMSIZ);
 671                 in_collision->ia_ipaddr = sender_ip->sin_addr;
 672                 in_collision->hw_len = sender_hw->sdl_alen < MAX_HW_LEN ? sender_hw->sdl_alen : MAX_HW_LEN;
 673                 bcopy(CONST_LLADDR(sender_hw), (caddr_t)in_collision->hw_addr, in_collision->hw_len);
 674                 ev_msg.vendor_code = KEV_VENDOR_APPLE;
 675                 ev_msg.kev_class = KEV_NETWORK_CLASS;
 676                 ev_msg.kev_subclass = KEV_INET_SUBCLASS;
 677                 ev_msg.event_code = KEV_INET_ARPCOLLISION;
 678                 ev_msg.dv[0].data_ptr = in_collision;
 679                 ev_msg.dv[0].data_length = sizeof(struct kev_in_collision) + in_collision->hw_len;
 680                 ev_msg.dv[1].data_length = 0;
 681                 kev_post_msg(&ev_msg);
 682
 683                 goto respond;
 684         }
 685
 686         /*
 687          * Look up the routing entry. If it doesn't exist and we are the
 688          * target, go ahead and create one.
 689          */
 690         error = arp_lookup_route(&sender_ip->sin_addr, (target_ip->sin_addr.s_addr ==
 691                                 best_ia->ia_addr.sin_addr.s_addr), 0, &route);
 692
 693         if (error || route == 0 || route->rt_gateway == 0) {
 694                 if (ipv4_ll_arp_aware != 0 && IN_LINKLOCAL(target_ip->sin_addr.s_addr)
 695                         && arpop == ARPOP_REQUEST && sender_ip->sin_addr.s_addr == 0) {
 696                         /*
 697                          * Verify this ARP probe doesn't conflict with an IPv4LL we know of
 698                          * on another interface.
 699                          */
 700                         error = arp_lookup_route(&target_ip->sin_addr, 0, 0, &route);
 701                         if (error == 0 && route && route->rt_gateway) {
 702                                 gateway = SDL(route->rt_gateway);
 703                                 if (route->rt_ifp != ifp &&
 704                                         (gateway->sdl_alen != sender_hw->sdl_alen ||
 705                                          bcmp(CONST_LLADDR(gateway), CONST_LLADDR(sender_hw),
 706                                          gateway->sdl_alen) != 0)) {
 707                                         /*
 708                                          * A node is probing for an IPv4LL we know exists on a
 709                                          * different interface. We respond with a conflicting probe
 710                                          * to force the new device to pick a different IPv4LL
 711                                          * address.
 712                                          */
 713                                         log(LOG_INFO,
 714                                                 "arp: %s on %s%d sent probe for %s, already on %s%d\n",
 715                                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 716                                                 ifp->if_name, ifp->if_unit,
 717                                                 inet_ntop(AF_INET, &target_ip->sin_addr, ipv4str,
 718                                                                   sizeof(ipv4str)),
 719                                                 route->rt_ifp->if_name, route->rt_ifp->if_unit);
 720                                         log(LOG_INFO,
 721                                                 "arp: sending conflicting probe to %s on %s%d\n",
 722                                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 723                                                 ifp->if_name, ifp->if_unit);
 724
 725                                         /*
 726                                          * Send a conservative unicast "ARP probe".
 727                                          * This should force the other device to pick a new number.
 728                                          * This will not force the device to pick a new number if the device
 729                                          * has already assigned that number.
 730                                          * This will not imply to the device that we own that address.
 731                                          */
 732                                         dlil_send_arp_internal(ifp, ARPOP_REQUEST,
 733                                                 (struct sockaddr_dl*)TAILQ_FIRST(&ifp->if_addrhead)->ifa_addr,
 734                                                 (const struct sockaddr*)sender_ip, sender_hw,
 735                                                 (const struct sockaddr*)target_ip);
 736                                 }
 737                         }
 738                 }
 739
 740                 goto respond;
 741         }
 742
 743         gateway = SDL(route->rt_gateway);
 744         if (route->rt_ifp != ifp) {
 745                 if (!IN_LINKLOCAL(sender_ip->sin_addr.s_addr) || (ifp->if_eflags & IFEF_ARPLL) == 0) {
 746                         if (log_arp_warnings)
 747                                 log(LOG_ERR, "arp: %s is on %s%d but got reply from %s on %s%d\n",
 748                                         inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 749                                                           sizeof(ipv4str)),
 750                                         route->rt_ifp->if_name,
 751                                         route->rt_ifp->if_unit,
 752                                         sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 753                                         ifp->if_name, ifp->if_unit);
 754                         goto respond;
 755                 }
 756                 else {
 757                         /* Don't change a permanent address */
 758                         if (route->rt_rmx.rmx_expire == 0) {
 759                                 goto respond;
 760                         }
 761
 762                         /*
 763                          * Don't change the cloned route away from the parent's interface
 764                          * if the address did resolve.
 765                          */
 766                         if (gateway->sdl_alen != 0 && route->rt_parent &&
 767                                 route->rt_parent->rt_ifp == route->rt_ifp) {
 768                                 goto respond;
 769                         }
 770
 771                         /* Change the interface when the existing route is on */
 772                         route->rt_ifp = ifp;
 773                         rtsetifa(route, &best_ia->ia_ifa);
 774                         gateway->sdl_index = ifp->if_index;
 775                 }
 776         }
 777
 778         if (gateway->sdl_alen && bcmp(LLADDR(gateway), CONST_LLADDR(sender_hw), gateway->sdl_alen)) {
 779                 if (route->rt_rmx.rmx_expire) {
 780                         char buf2[3 * MAX_HW_LEN];
 781                         log(LOG_INFO, "arp: %s moved from %s to %s on %s%d\n",
 782                                 inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 783                                                   sizeof(ipv4str)),
 784                                 sdl_addr_to_hex(gateway, buf, sizeof(buf)),
 785                                 sdl_addr_to_hex(sender_hw, buf2, sizeof(buf2)), ifp->if_name,
 786                                 ifp->if_unit);
 787                 }
 788                 else {
 789                         log(LOG_ERR,
 790                                 "arp: %s attempts to modify permanent entry for %s on %s%d\n",
 791                                 sdl_addr_to_hex(sender_hw, buf, sizeof(buf)),
 792                                 inet_ntop(AF_INET, &sender_ip->sin_addr, ipv4str,
 793                                                   sizeof(ipv4str)),
 794                                 ifp->if_name, ifp->if_unit);
 795                         goto respond;
 796                 }
 797         }
 798
 799         /* Copy the sender hardware address in to the route's gateway address */
 800         gateway->sdl_alen = sender_hw->sdl_alen;
 801         bcopy(CONST_LLADDR(sender_hw), LLADDR(gateway), gateway->sdl_alen);
 802
 803         /* Update the expire time for the route and clear the reject flag */
 804         getmicrotime(&timenow);
 805         if (route->rt_rmx.rmx_expire)
 806                 route->rt_rmx.rmx_expire = timenow.tv_sec + arpt_keep;
 807         route->rt_flags &= ~RTF_REJECT;
 808
 809         /* update the llinfo, send a queued packet if there is one */
 810         llinfo = (struct llinfo_arp*)route->rt_llinfo;
 811         llinfo->la_asked = 0;
 812         if (llinfo->la_hold) {
 813                 struct mbuf *m0;
 814                 m0 = llinfo->la_hold;
 815                 llinfo->la_hold = 0;
 816
 817                 /* Should we a reference on the route first? */
 818                 lck_mtx_unlock(rt_mtx);
 819                 dlil_output(ifp, PF_INET, m0, (caddr_t)route, rt_key(route), 0);
 820                 lck_mtx_lock(rt_mtx);
 821         }
 822
 823 respond:
 824         if (arpop != ARPOP_REQUEST) {
 825                 lck_mtx_unlock(rt_mtx);
 826                 return 0;
 827         }
 828
 829         /* If we are not the target, check if we should proxy */
 830         if (target_ip->sin_addr.s_addr != best_ia->ia_addr.sin_addr.s_addr) {
 831
 832                 /* Find a proxy route */
 833                 error = arp_lookup_route(&target_ip->sin_addr, 0, SIN_PROXY, &route);
 834                 if (error || route == NULL) {
 835
 836                         /* We don't have a route entry indicating we should use proxy */
 837                         /* If we aren't supposed to proxy all, we are done */
 838                         if (!arp_proxyall) {
 839                                 lck_mtx_unlock(rt_mtx);
 840                                 return 0;
 841                         }
 842
 843                         /* See if we have a route to the target ip before we proxy it */
 844                         route = rtalloc1_locked((const struct sockaddr*)target_ip, 0, 0);
 845                         if (!route) {
 846                                 lck_mtx_unlock(rt_mtx);
 847                                 return 0;
 848                         }
 849
 850                         /*
 851                          * Don't proxy for hosts already on the same interface.
 852                          */
 853                         if (route->rt_ifp == ifp) {
 854                                 rtfree_locked(route);
 855                                 lck_mtx_unlock(rt_mtx);
 856                                 return 0;
 857                         }
 858                 }
 859         }
 860         lck_mtx_unlock(rt_mtx);
 861
 862         dlil_send_arp(ifp, ARPOP_REPLY, NULL, (const struct sockaddr*)target_ip,
 863                 sender_hw, (const struct sockaddr*)sender_ip);
 864
 865         return 0;
 866 }
 867
 868 void
 869 arp_ifinit(
 870         struct ifnet *ifp,
 871         struct ifaddr *ifa)
 872 {
 873         ifa->ifa_rtrequest = arp_rtrequest;
 874         ifa->ifa_flags |= RTF_CLONING;
 875         dlil_send_arp(ifp, ARPOP_REQUEST, NULL, ifa->ifa_addr, NULL, ifa->ifa_addr);
 876 }