sys/netinet/if_ether.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)if_ether.c  8.1 (Berkeley) 6/10/93
  34  * $FreeBSD$
  35  */
  36
  37 /*
  38  * Ethernet address resolution protocol.
  39  * TODO:
  40  *      add "inuse/lock" bit (or ref. count) along with valid bit
  41  */
  42
  43 #include "opt_inet.h"
  44 #include "opt_bdg.h"
  45
  46 #include <sys/param.h>
  47 #include <sys/kernel.h>
  48 #include <sys/queue.h>
  49 #include <sys/sysctl.h>
  50 #include <sys/systm.h>
  51 #include <sys/mbuf.h>
  52 #include <sys/malloc.h>
  53 #include <sys/socket.h>
  54 #include <sys/syslog.h>
  55
  56 #include <net/if.h>
  57 #include <net/if_dl.h>
  58 #include <net/if_types.h>
  59 #include <net/route.h>
  60 #include <net/netisr.h>
  61
  62 #include <netinet/in.h>
  63 #include <netinet/in_var.h>
  64 #include <netinet/if_ether.h>
  65
  66 #include <net/iso88025.h>
  67
  68 #define SIN(s) ((struct sockaddr_in *)s)
  69 #define SDL(s) ((struct sockaddr_dl *)s)
  70
  71 SYSCTL_DECL(_net_link_ether);
  72 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
  73
  74 /* timer values */
  75 static int arpt_prune = (5*60*1); /* walk list every 5 minutes */
  76 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
  77 static int arpt_down = 20;      /* once declared down, don't send for 20 sec */
  78
  79 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW,
  80            &arpt_prune, 0, "");
  81 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  82            &arpt_keep, 0, "");
  83 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, host_down_time, CTLFLAG_RW,
  84            &arpt_down, 0, "");
  85
  86 #define rt_expire rt_rmx.rmx_expire
  87
  88 struct llinfo_arp {
  89         LIST_ENTRY(llinfo_arp) la_le;
  90         struct  rtentry *la_rt;
  91         struct  mbuf *la_hold;          /* last packet until resolved/timeout */
  92         long    la_asked;               /* last time we QUERIED for this addr */
  93 #define la_timer la_rt->rt_rmx.rmx_expire /* deletion time in seconds */
  94 };
  95
  96 static  LIST_HEAD(, llinfo_arp) llinfo_arp;
  97
  98 struct  ifqueue arpintrq = {0, 0, 0, 50};
  99 static int      arp_inuse, arp_allocated;
 100
 101 static int      arp_maxtries = 5;
 102 static int      useloopback = 1; /* use loopback interface for local traffic */
 103 static int      arp_proxyall = 0;
 104
 105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
 106            &arp_maxtries, 0, "");
 107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
 108            &useloopback, 0, "");
 109 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
 110            &arp_proxyall, 0, "");
 111
 112 static void     arp_rtrequest __P((int, struct rtentry *, struct sockaddr *));
 113 static void     arprequest __P((struct arpcom *,
 114                         struct in_addr *, struct in_addr *, u_char *));
 115 static void     arpintr __P((void));
 116 static void     arptfree __P((struct llinfo_arp *));
 117 static void     arptimer __P((void *));
 118 static struct llinfo_arp
 119                 *arplookup __P((u_long, int, int));
 120 #ifdef INET
 121 static void     in_arpinput __P((struct mbuf *));
 122 #endif
 123
 124 /*
 125  * Timeout routine.  Age arp_tab entries periodically.
 126  */
 127 /* ARGSUSED */
 128 static void
 129 arptimer(ignored_arg)
 130         void *ignored_arg;
 131 {
 132         int s = splnet();
 133         register struct llinfo_arp *la = llinfo_arp.lh_first;
 134         struct llinfo_arp *ola;
 135
 136         timeout(arptimer, (caddr_t)0, arpt_prune * hz);
 137         while ((ola = la) != 0) {
 138                 register struct rtentry *rt = la->la_rt;
 139                 la = la->la_le.le_next;
 140                 if (rt->rt_expire && rt->rt_expire <= time_second)
 141                         arptfree(ola); /* timer has expired, clear */
 142         }
 143         splx(s);
 144 }
 145
 146 /*
 147  * Parallel to llc_rtrequest.
 148  */
 149 static void
 150 arp_rtrequest(req, rt, sa)
 151         int req;
 152         register struct rtentry *rt;
 153         struct sockaddr *sa;
 154 {
 155         register struct sockaddr *gate = rt->rt_gateway;
 156         register struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
 157         static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
 158         static int arpinit_done;
 159
 160         if (!arpinit_done) {
 161                 arpinit_done = 1;
 162                 LIST_INIT(&llinfo_arp);
 163                 timeout(arptimer, (caddr_t)0, hz);
 164         }
 165         if (rt->rt_flags & RTF_GATEWAY)
 166                 return;
 167         switch (req) {
 168
 169         case RTM_ADD:
 170                 /*
 171                  * XXX: If this is a manually added route to interface
 172                  * such as older version of routed or gated might provide,
 173                  * restore cloning bit.
 174                  */
 175                 if ((rt->rt_flags & RTF_HOST) == 0 &&
 176                     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
 177                         rt->rt_flags |= RTF_CLONING;
 178                 if (rt->rt_flags & RTF_CLONING) {
 179                         /*
 180                          * Case 1: This route should come from a route to iface.
 181                          */
 182                         rt_setgate(rt, rt_key(rt),
 183                                         (struct sockaddr *)&null_sdl);
 184                         gate = rt->rt_gateway;
 185                         SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 186                         SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 187                         rt->rt_expire = time_second;
 188                         break;
 189                 }
 190                 /* Announce a new entry if requested. */
 191                 if (rt->rt_flags & RTF_ANNOUNCE)
 192                         arprequest((struct arpcom *)rt->rt_ifp,
 193                             &SIN(rt_key(rt))->sin_addr,
 194                             &SIN(rt_key(rt))->sin_addr,
 195                             (u_char *)LLADDR(SDL(gate)));
 196                 /*FALLTHROUGH*/
 197         case RTM_RESOLVE:
 198                 if (gate->sa_family != AF_LINK ||
 199                     gate->sa_len < sizeof(null_sdl)) {
 200                         log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
 201                         break;
 202                 }
 203                 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
 204                 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
 205                 if (la != 0)
 206                         break; /* This happens on a route change */
 207                 /*
 208                  * Case 2:  This route may come from cloning, or a manual route
 209                  * add with a LL address.
 210                  */
 211                 R_Malloc(la, struct llinfo_arp *, sizeof(*la));
 212                 rt->rt_llinfo = (caddr_t)la;
 213                 if (la == 0) {
 214                         log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
 215                         break;
 216                 }
 217                 arp_inuse++, arp_allocated++;
 218                 Bzero(la, sizeof(*la));
 219                 la->la_rt = rt;
 220                 rt->rt_flags |= RTF_LLINFO;
 221                 LIST_INSERT_HEAD(&llinfo_arp, la, la_le);
 222
 223 #ifdef INET
 224                 /*
 225                  * This keeps the multicast addresses from showing up
 226                  * in `arp -a' listings as unresolved.  It's not actually
 227                  * functional.  Then the same for broadcast.
 228                  */
 229                 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr))) {
 230                         ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
 231                                                LLADDR(SDL(gate)));
 232                         SDL(gate)->sdl_alen = 6;
 233                         rt->rt_expire = 0;
 234                 }
 235                 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
 236                         memcpy(LLADDR(SDL(gate)), etherbroadcastaddr, 6);
 237                         SDL(gate)->sdl_alen = 6;
 238                         rt->rt_expire = 0;
 239                 }
 240 #endif
 241
 242                 if (SIN(rt_key(rt))->sin_addr.s_addr ==
 243                     (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) {
 244                     /*
 245                      * This test used to be
 246                      *  if (loif.if_flags & IFF_UP)
 247                      * It allowed local traffic to be forced
 248                      * through the hardware by configuring the loopback down.
 249                      * However, it causes problems during network configuration
 250                      * for boards that can't receive packets they send.
 251                      * It is now necessary to clear "useloopback" and remove
 252                      * the route to force traffic out to the hardware.
 253                      */
 254                         rt->rt_expire = 0;
 255                         Bcopy(((struct arpcom *)rt->rt_ifp)->ac_enaddr,
 256                                 LLADDR(SDL(gate)), SDL(gate)->sdl_alen = 6);
 257                         if (useloopback)
 258                                 rt->rt_ifp = loif;
 259
 260                 }
 261                 break;
 262
 263         case RTM_DELETE:
 264                 if (la == 0)
 265                         break;
 266                 arp_inuse--;
 267                 LIST_REMOVE(la, la_le);
 268                 rt->rt_llinfo = 0;
 269                 rt->rt_flags &= ~RTF_LLINFO;
 270                 if (la->la_hold)
 271                         m_freem(la->la_hold);
 272                 Free((caddr_t)la);
 273         }
 274 }
 275
 276 /*
 277  * Broadcast an ARP request. Caller specifies:
 278  *      - arp header source ip address
 279  *      - arp header target ip address
 280  *      - arp header source ethernet address
 281  */
 282 static void
 283 arprequest(ac, sip, tip, enaddr)
 284         register struct arpcom *ac;
 285         register struct in_addr *sip, *tip;
 286         register u_char *enaddr;
 287 {
 288         register struct mbuf *m;
 289         register struct ether_header *eh;
 290         register struct ether_arp *ea;
 291         struct sockaddr sa;
 292
 293         if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
 294                 return;
 295         m->m_pkthdr.rcvif = (struct ifnet *)0;
 296         switch (ac->ac_if.if_type) {
 297         case IFT_ISO88025:
 298                 m->m_len = sizeof(*ea) + 10;
 299                 m->m_pkthdr.len = sizeof(*ea) + 10;
 300                 MH_ALIGN(m, sizeof(*ea) + 10);
 301                 (void)memcpy(mtod(m, caddr_t),
 302                     "\x82\x40\xaa\xaa\x03\x00\x00\x00\x08\x06", 10);
 303                 (void)memcpy(sa.sa_data, etherbroadcastaddr, 6);
 304                 (void)memcpy(sa.sa_data + 6, enaddr, 6);
 305                 sa.sa_data[6] |= 0x80;
 306                 sa.sa_data[12] = 0x10;
 307                 sa.sa_data[13] = 0x40;
 308                 ea = (struct ether_arp *)(mtod(m, char *) + 10);
 309                 bzero((caddr_t)ea, sizeof (*ea));
 310                 ea->arp_hrd = htons(ARPHRD_IEEE802);
 311                 break;
 312         case IFT_FDDI:
 313         case IFT_ETHER:
 314                 /*
 315                  * This may not be correct for types not explicitly
 316                  * listed, but this is our best guess
 317                  */
 318         default:
 319                 m->m_len = sizeof(*ea);
 320                 m->m_pkthdr.len = sizeof(*ea);
 321                 MH_ALIGN(m, sizeof(*ea));
 322                 ea = mtod(m, struct ether_arp *);
 323                 eh = (struct ether_header *)sa.sa_data;
 324                 bzero((caddr_t)ea, sizeof (*ea));
 325                 /* if_output will not swap */
 326                 eh->ether_type = htons(ETHERTYPE_ARP);
 327                 (void)memcpy(eh->ether_dhost, etherbroadcastaddr,
 328                     sizeof(eh->ether_dhost));
 329                 ea->arp_hrd = htons(ARPHRD_ETHER);
 330                 break;
 331         }
 332         ea->arp_pro = htons(ETHERTYPE_IP);
 333         ea->arp_hln = sizeof(ea->arp_sha);      /* hardware address length */
 334         ea->arp_pln = sizeof(ea->arp_spa);      /* protocol address length */
 335         ea->arp_op = htons(ARPOP_REQUEST);
 336         (void)memcpy(ea->arp_sha, enaddr, sizeof(ea->arp_sha));
 337         (void)memcpy(ea->arp_spa, sip, sizeof(ea->arp_spa));
 338         (void)memcpy(ea->arp_tpa, tip, sizeof(ea->arp_tpa));
 339         sa.sa_family = AF_UNSPEC;
 340         sa.sa_len = sizeof(sa);
 341         (*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0);
 342 }
 343
 344 /*
 345  * Resolve an IP address into an ethernet address.  If success,
 346  * desten is filled in.  If there is no entry in arptab,
 347  * set one up and broadcast a request for the IP address.
 348  * Hold onto this mbuf and resend it once the address
 349  * is finally resolved.  A return value of 1 indicates
 350  * that desten has been filled in and the packet should be sent
 351  * normally; a 0 return indicates that the packet has been
 352  * taken over here, either now or for later transmission.
 353  */
 354 int
 355 arpresolve(ac, rt, m, dst, desten, rt0)
 356         register struct arpcom *ac;
 357         register struct rtentry *rt;
 358         struct mbuf *m;
 359         register struct sockaddr *dst;
 360         register u_char *desten;
 361         struct rtentry *rt0;
 362 {
 363         register struct llinfo_arp *la = 0;
 364         struct sockaddr_dl *sdl;
 365
 366         if (m->m_flags & M_BCAST) {     /* broadcast */
 367                 (void)memcpy(desten, etherbroadcastaddr, sizeof(etherbroadcastaddr));
 368                 return (1);
 369         }
 370         if (m->m_flags & M_MCAST) {     /* multicast */
 371                 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
 372                 return(1);
 373         }
 374         if (rt)
 375                 la = (struct llinfo_arp *)rt->rt_llinfo;
 376         if (la == 0) {
 377                 la = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0);
 378                 if (la)
 379                         rt = la->la_rt;
 380         }
 381         if (la == 0 || rt == 0) {
 382                 log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s%s%s\n",
 383                         inet_ntoa(SIN(dst)->sin_addr), la ? "la" : "",
 384                                 rt ? "rt" : "");
 385                 m_freem(m);
 386                 return (0);
 387         }
 388         sdl = SDL(rt->rt_gateway);
 389         /*
 390          * Check the address family and length is valid, the address
 391          * is resolved; otherwise, try to resolve.
 392          */
 393         if ((rt->rt_expire == 0 || rt->rt_expire > time_second) &&
 394             sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
 395                 bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
 396                 return 1;
 397         }
 398         /*
 399          * There is an arptab entry, but no ethernet address
 400          * response yet.  Replace the held mbuf with this
 401          * latest one.
 402          */
 403         if (la->la_hold)
 404                 m_freem(la->la_hold);
 405         la->la_hold = m;
 406         if (rt->rt_expire) {
 407                 rt->rt_flags &= ~RTF_REJECT;
 408                 if (la->la_asked == 0 || rt->rt_expire != time_second) {
 409                         rt->rt_expire = time_second;
 410                         if (la->la_asked++ < arp_maxtries)
 411                             arprequest(ac,
 412                                 &SIN(rt->rt_ifa->ifa_addr)->sin_addr,
 413                                 &SIN(dst)->sin_addr, ac->ac_enaddr);
 414                         else {
 415                                 rt->rt_flags |= RTF_REJECT;
 416                                 rt->rt_expire += arpt_down;
 417                                 la->la_asked = 0;
 418                         }
 419
 420                 }
 421         }
 422         return (0);
 423 }
 424
 425 /*
 426  * Common length and type checks are done here,
 427  * then the protocol-specific routine is called.
 428  */
 429 static void
 430 arpintr()
 431 {
 432         register struct mbuf *m;
 433         register struct arphdr *ar;
 434         int s;
 435
 436         while (arpintrq.ifq_head) {
 437                 s = splimp();
 438                 IF_DEQUEUE(&arpintrq, m);
 439                 splx(s);
 440                 if (m == 0 || (m->m_flags & M_PKTHDR) == 0)
 441                         panic("arpintr");
 442                 if (m->m_len >= sizeof(struct arphdr) &&
 443                     (ar = mtod(m, struct arphdr *)) &&
 444                     (ntohs(ar->ar_hrd) == ARPHRD_ETHER ||
 445                      ntohs(ar->ar_hrd) == ARPHRD_IEEE802) &&
 446                     m->m_len >=
 447                       sizeof(struct arphdr) + 2 * ar->ar_hln + 2 * ar->ar_pln)
 448
 449                             switch (ntohs(ar->ar_pro)) {
 450
 451 #ifdef INET
 452                             case ETHERTYPE_IP:
 453                                     in_arpinput(m);
 454                                     continue;
 455 #endif
 456                             }
 457                 m_freem(m);
 458         }
 459 }
 460
 461 NETISR_SET(NETISR_ARP, arpintr);
 462
 463
 464 #ifdef INET
 465 /*
 466  * ARP for Internet protocols on 10 Mb/s Ethernet.
 467  * Algorithm is that given in RFC 826.
 468  * In addition, a sanity check is performed on the sender
 469  * protocol address, to catch impersonators.
 470  * We no longer handle negotiations for use of trailer protocol:
 471  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
 472  * along with IP replies if we wanted trailers sent to us,
 473  * and also sent them in response to IP replies.
 474  * This allowed either end to announce the desire to receive
 475  * trailer packets.
 476  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
 477  * but formerly didn't normally send requests.
 478  */
 479 static void
 480 in_arpinput(m)
 481         struct mbuf *m;
 482 {
 483         register struct ether_arp *ea;
 484         register struct arpcom *ac = (struct arpcom *)m->m_pkthdr.rcvif;
 485         struct ether_header *eh;
 486         struct iso88025_header *th = (struct iso88025_header *)0;
 487         register struct llinfo_arp *la = 0;
 488         register struct rtentry *rt;
 489         struct in_ifaddr *ia, *maybe_ia = 0;
 490         struct sockaddr_dl *sdl;
 491         struct sockaddr sa;
 492         struct in_addr isaddr, itaddr, myaddr;
 493         int op;
 494
 495         ea = mtod(m, struct ether_arp *);
 496         op = ntohs(ea->arp_op);
 497         (void)memcpy(&isaddr, ea->arp_spa, sizeof (isaddr));
 498         (void)memcpy(&itaddr, ea->arp_tpa, sizeof (itaddr));
 499         for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next)
 500 #ifdef BRIDGE
 501                 /*
 502                  * For a bridge, we want to check the address irrespective
 503                  * of the receive interface. (This will change slightly
 504                  * when we have clusters of interfaces).
 505                  */
 506                 {
 507 #else
 508                 if (ia->ia_ifp == &ac->ac_if) {
 509 #endif
 510                         maybe_ia = ia;
 511                         if ((itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) ||
 512                              (isaddr.s_addr == ia->ia_addr.sin_addr.s_addr))
 513                                 break;
 514                 }
 515         if (maybe_ia == 0) {
 516                 m_freem(m);
 517                 return;
 518         }
 519         myaddr = ia ? ia->ia_addr.sin_addr : maybe_ia->ia_addr.sin_addr;
 520         if (!bcmp((caddr_t)ea->arp_sha, (caddr_t)ac->ac_enaddr,
 521             sizeof (ea->arp_sha))) {
 522                 m_freem(m);     /* it's from me, ignore it. */
 523                 return;
 524         }
 525         if (!bcmp((caddr_t)ea->arp_sha, (caddr_t)etherbroadcastaddr,
 526             sizeof (ea->arp_sha))) {
 527                 log(LOG_ERR,
 528                     "arp: ether address is broadcast for IP address %s!\n",
 529                     inet_ntoa(isaddr));
 530                 m_freem(m);
 531                 return;
 532         }
 533         if (isaddr.s_addr == myaddr.s_addr) {
 534                 log(LOG_ERR,
 535                    "arp: %6D is using my IP address %s!\n",
 536                    ea->arp_sha, ":", inet_ntoa(isaddr));
 537                 itaddr = myaddr;
 538                 goto reply;
 539         }
 540         la = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0);
 541         if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) {
 542 #ifndef BRIDGE /* the following is not an error when doing bridging */
 543                 if (rt->rt_ifp != &ac->ac_if) {
 544                         log(LOG_ERR, "arp: %s is on %s%d but got reply from %6D on %s%d\n",
 545                             inet_ntoa(isaddr),
 546                             rt->rt_ifp->if_name, rt->rt_ifp->if_unit,
 547                             ea->arp_sha, ":",
 548                             ac->ac_if.if_name, ac->ac_if.if_unit);
 549                         goto reply;
 550                 }
 551 #endif
 552                 if (sdl->sdl_alen &&
 553                     bcmp((caddr_t)ea->arp_sha, LLADDR(sdl), sdl->sdl_alen)) {
 554                         if (rt->rt_expire)
 555                             log(LOG_INFO, "arp: %s moved from %6D to %6D on %s%d\n",
 556                                 inet_ntoa(isaddr), (u_char *)LLADDR(sdl), ":",
 557                                 ea->arp_sha, ":",
 558                                 ac->ac_if.if_name, ac->ac_if.if_unit);
 559                         else {
 560                             log(LOG_ERR,
 561                                 "arp: %6D attempts to modify permanent entry for %s on %s%d\n",
 562                                 ea->arp_sha, ":", inet_ntoa(isaddr),
 563                                 ac->ac_if.if_name, ac->ac_if.if_unit);
 564                             goto reply;
 565                         }
 566                 }
 567                 (void)memcpy(LLADDR(sdl), ea->arp_sha, sizeof(ea->arp_sha));
 568                 sdl->sdl_alen = sizeof(ea->arp_sha);
 569                 sdl->sdl_rcf = NULL;
 570                 /*
 571                  * If we receive an arp from a token-ring station over
 572                  * a token-ring nic then try to save the source
 573                  * routing info.
 574                  */
 575                 if (ac->ac_if.if_type == IFT_ISO88025) {
 576                         th = (struct iso88025_header *)m->m_pkthdr.header;
 577                         if ((th->iso88025_shost[0] & 0x80) &&
 578                             ((th->rcf & 0x001f) > 2)) {
 579                                 sdl->sdl_rcf = (th->rcf & 0x8000) ?
 580                                     (th->rcf & 0x7fff) :
 581                                     (th->rcf | 0x8000);
 582                                 memcpy(sdl->sdl_route, th->rseg,
 583                                     (th->rcf & 0x001f)  - 2);
 584                                 sdl->sdl_rcf = sdl->sdl_rcf & 0xff1f;
 585                                 /*
 586                                  * Set up source routing information for
 587                                  * reply packet (XXX)
 588                                  */
 589                                 m->m_data -= (th->rcf & 0x001f);
 590                                 m->m_len  += (th->rcf & 0x001f);
 591                                 m->m_pkthdr.len += (th->rcf & 0x001f);
 592                         } else {
 593                                 th->iso88025_shost[0] &= 0x7f;
 594                         }
 595                         m->m_data -= 8;
 596                         m->m_len  += 8;
 597                         m->m_pkthdr.len += 8;
 598                         th->rcf = sdl->sdl_rcf;
 599                 } else {
 600                         sdl->sdl_rcf = NULL;
 601                 }
 602                 if (rt->rt_expire)
 603                         rt->rt_expire = time_second + arpt_keep;
 604                 rt->rt_flags &= ~RTF_REJECT;
 605                 la->la_asked = 0;
 606                 if (la->la_hold) {
 607                         (*ac->ac_if.if_output)(&ac->ac_if, la->la_hold,
 608                                 rt_key(rt), rt);
 609                         la->la_hold = 0;
 610                 }
 611         }
 612 reply:
 613         if (op != ARPOP_REQUEST) {
 614                 m_freem(m);
 615                 return;
 616         }
 617         if (itaddr.s_addr == myaddr.s_addr) {
 618                 /* I am the target */
 619                 (void)memcpy(ea->arp_tha, ea->arp_sha, sizeof(ea->arp_sha));
 620                 (void)memcpy(ea->arp_sha, ac->ac_enaddr, sizeof(ea->arp_sha));
 621         } else {
 622                 la = arplookup(itaddr.s_addr, 0, SIN_PROXY);
 623                 if (la == NULL) {
 624                         struct sockaddr_in sin;
 625
 626                         if (!arp_proxyall) {
 627                                 m_freem(m);
 628                                 return;
 629                         }
 630
 631                         bzero(&sin, sizeof sin);
 632                         sin.sin_family = AF_INET;
 633                         sin.sin_len = sizeof sin;
 634                         sin.sin_addr = itaddr;
 635
 636                         rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
 637                         if (!rt) {
 638                                 m_freem(m);
 639                                 return;
 640                         }
 641                         /*
 642                          * Don't send proxies for nodes on the same interface
 643                          * as this one came out of, or we'll get into a fight
 644                          * over who claims what Ether address.
 645                          */
 646                         if (rt->rt_ifp == &ac->ac_if) {
 647                                 rtfree(rt);
 648                                 m_freem(m);
 649                                 return;
 650                         }
 651                         (void)memcpy(ea->arp_tha, ea->arp_sha, sizeof(ea->arp_sha));
 652                         (void)memcpy(ea->arp_sha, ac->ac_enaddr, sizeof(ea->arp_sha));
 653                         rtfree(rt);
 654 #ifdef DEBUG_PROXY
 655                         printf("arp: proxying for %s\n",
 656                                inet_ntoa(itaddr));
 657 #endif
 658                 } else {
 659                         rt = la->la_rt;
 660                         (void)memcpy(ea->arp_tha, ea->arp_sha, sizeof(ea->arp_sha));
 661                         sdl = SDL(rt->rt_gateway);
 662                         (void)memcpy(ea->arp_sha, LLADDR(sdl), sizeof(ea->arp_sha));
 663                 }
 664         }
 665
 666         (void)memcpy(ea->arp_tpa, ea->arp_spa, sizeof(ea->arp_spa));
 667         (void)memcpy(ea->arp_spa, &itaddr, sizeof(ea->arp_spa));
 668         ea->arp_op = htons(ARPOP_REPLY);
 669         ea->arp_pro = htons(ETHERTYPE_IP); /* let's be sure! */
 670         switch (ac->ac_if.if_type) {
 671         case IFT_ISO88025:
 672                 /* Re-arrange the source/dest address */
 673                 memcpy(th->iso88025_dhost, th->iso88025_shost,
 674                     sizeof(th->iso88025_dhost));
 675                 memcpy(th->iso88025_shost, ac->ac_enaddr,
 676                     sizeof(th->iso88025_shost));
 677                 /* Set the source routing bit if neccesary */
 678                 if (th->iso88025_dhost[0] & 0x80) {
 679                         th->iso88025_dhost[0] &= 0x7f;
 680                         if ((th->rcf & 0x001f) - 2)
 681                                 th->iso88025_shost[0] |= 0x80;
 682                 }
 683                 /* Copy the addresses, ac and fc into sa_data */
 684                 memcpy(sa.sa_data, th->iso88025_dhost,
 685                     sizeof(th->iso88025_dhost) * 2);
 686                 sa.sa_data[(sizeof(th->iso88025_dhost) * 2)] = 0x10;
 687                 sa.sa_data[(sizeof(th->iso88025_dhost) * 2) + 1] = 0x40;
 688                 break;
 689         case IFT_ETHER:
 690         case IFT_FDDI:
 691         /*
 692          * May not be correct for types not explictly
 693          * listed, but it is our best guess.
 694          */
 695         default:
 696                 eh = (struct ether_header *)sa.sa_data;
 697                 (void)memcpy(eh->ether_dhost, ea->arp_tha,
 698                     sizeof(eh->ether_dhost));
 699                 eh->ether_type = htons(ETHERTYPE_ARP);
 700                 break;
 701         }
 702         sa.sa_family = AF_UNSPEC;
 703         sa.sa_len = sizeof(sa);
 704         (*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0);
 705         return;
 706 }
 707 #endif
 708
 709 /*
 710  * Free an arp entry.
 711  */
 712 static void
 713 arptfree(la)
 714         register struct llinfo_arp *la;
 715 {
 716         register struct rtentry *rt = la->la_rt;
 717         register struct sockaddr_dl *sdl;
 718         if (rt == 0)
 719                 panic("arptfree");
 720         if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) &&
 721             sdl->sdl_family == AF_LINK) {
 722                 sdl->sdl_alen = 0;
 723                 la->la_asked = 0;
 724                 rt->rt_flags &= ~RTF_REJECT;
 725                 return;
 726         }
 727         rtrequest(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt),
 728                         0, (struct rtentry **)0);
 729 }
 730 /*
 731  * Lookup or enter a new address in arptab.
 732  */
 733 static struct llinfo_arp *
 734 arplookup(addr, create, proxy)
 735         u_long addr;
 736         int create, proxy;
 737 {
 738         register struct rtentry *rt;
 739         static struct sockaddr_inarp sin = {sizeof(sin), AF_INET };
 740         const char *why = 0;
 741
 742         sin.sin_addr.s_addr = addr;
 743         sin.sin_other = proxy ? SIN_PROXY : 0;
 744         rt = rtalloc1((struct sockaddr *)&sin, create, 0UL);
 745         if (rt == 0)
 746                 return (0);
 747         rt->rt_refcnt--;
 748
 749         if (rt->rt_flags & RTF_GATEWAY)
 750                 why = "host is not on local network";
 751         else if ((rt->rt_flags & RTF_LLINFO) == 0)
 752                 why = "could not allocate llinfo";
 753         else if (rt->rt_gateway->sa_family != AF_LINK)
 754                 why = "gateway route is not ours";
 755
 756         if (why && create) {
 757                 log(LOG_DEBUG, "arplookup %s failed: %s\n",
 758                     inet_ntoa(sin.sin_addr), why);
 759                 return 0;
 760         } else if (why) {
 761                 return 0;
 762         }
 763         return ((struct llinfo_arp *)rt->rt_llinfo);
 764 }
 765
 766 void
 767 arp_ifinit(ac, ifa)
 768         struct arpcom *ac;
 769         struct ifaddr *ifa;
 770 {
 771         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
 772                 arprequest(ac, &IA_SIN(ifa)->sin_addr,
 773                                &IA_SIN(ifa)->sin_addr, ac->ac_enaddr);
 774         ifa->ifa_rtrequest = arp_rtrequest;
 775         ifa->ifa_flags |= RTF_CLONING;
 776 }