if_ether.c revision 1817
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 * $Id$ 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 <sys/param.h> 44#include <sys/systm.h> 45#include <sys/malloc.h> 46#include <sys/mbuf.h> 47#include <sys/socket.h> 48#include <sys/time.h> 49#include <sys/kernel.h> 50#include <sys/errno.h> 51#include <sys/ioctl.h> 52#include <sys/syslog.h> 53 54#include <net/if.h> 55#include <net/if_dl.h> 56#include <net/route.h> 57 58#include <netinet/in.h> 59#include <netinet/in_systm.h> 60#include <netinet/in_var.h> 61#include <netinet/ip.h> 62#include <netinet/if_ether.h> 63 64#define SIN(s) ((struct sockaddr_in *)s) 65#define SDL(s) ((struct sockaddr_dl *)s) 66#define SRP(s) ((struct sockaddr_inarp *)s) 67 68/* 69 * ARP trailer negotiation. Trailer protocol is not IP specific, 70 * but ARP request/response use IP addresses. 71 */ 72#define ETHERTYPE_IPTRAILERS ETHERTYPE_TRAIL 73 74 75/* timer values */ 76int arpt_prune = (5*60*1); /* walk list every 5 minutes */ 77int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */ 78int arpt_down = 20; /* once declared down, don't send for 20 secs */ 79#define rt_expire rt_rmx.rmx_expire 80 81static void arprequest __P((struct arpcom *, u_long *, u_long *, u_char *)); 82static void arptfree __P((struct llinfo_arp *)); 83static void arptimer __P((void *)); 84static struct llinfo_arp *arplookup __P((u_long, int, int)); 85static void in_arpinput __P((struct mbuf *)); 86 87extern struct ifnet loif; 88extern struct timeval time; 89struct llinfo_arp llinfo_arp = {&llinfo_arp, &llinfo_arp}; 90struct ifqueue arpintrq = {0, 0, 0, 50}; 91int arp_inuse, arp_allocated, arp_intimer; 92int arp_maxtries = 5; 93int useloopback = 1; /* use loopback interface for local traffic */ 94int arpinit_done = 0; 95 96/* 97 * Timeout routine. Age arp_tab entries periodically. 98 */ 99/* ARGSUSED */ 100static void 101arptimer(ignored_arg) 102 void *ignored_arg; 103{ 104 int s = splnet(); 105 register struct llinfo_arp *la = llinfo_arp.la_next; 106 107 timeout(arptimer, (caddr_t)0, arpt_prune * hz); 108 while (la != &llinfo_arp) { 109 register struct rtentry *rt = la->la_rt; 110 la = la->la_next; 111 if (rt->rt_expire && rt->rt_expire <= time.tv_sec) 112 arptfree(la->la_prev); /* timer has expired, clear */ 113 } 114 splx(s); 115} 116 117/* 118 * Parallel to llc_rtrequest. 119 */ 120void 121arp_rtrequest(req, rt, sa) 122 int req; 123 register struct rtentry *rt; 124 struct sockaddr *sa; 125{ 126 register struct sockaddr *gate = rt->rt_gateway; 127 register struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo; 128 static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK}; 129 130 if (!arpinit_done) { 131 arpinit_done = 1; 132 timeout(arptimer, (caddr_t)0, hz); 133 } 134 if (rt->rt_flags & RTF_GATEWAY) 135 return; 136 switch (req) { 137 138 case RTM_ADD: 139 /* 140 * XXX: If this is a manually added route to interface 141 * such as older version of routed or gated might provide, 142 * restore cloning bit. 143 */ 144 if ((rt->rt_flags & RTF_HOST) == 0 && 145 SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff) 146 rt->rt_flags |= RTF_CLONING; 147 if (rt->rt_flags & RTF_CLONING) { 148 /* 149 * Case 1: This route should come from a route to iface. 150 */ 151 rt_setgate(rt, rt_key(rt), 152 (struct sockaddr *)&null_sdl); 153 gate = rt->rt_gateway; 154 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 155 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 156 rt->rt_expire = time.tv_sec; 157 break; 158 } 159 /* Announce a new entry if requested. */ 160 if (rt->rt_flags & RTF_ANNOUNCE) 161 arprequest((struct arpcom *)rt->rt_ifp, 162 &SIN(rt_key(rt))->sin_addr.s_addr, 163 &SIN(rt_key(rt))->sin_addr.s_addr, 164 (u_char *)LLADDR(SDL(gate))); 165 /*FALLTHROUGH*/ 166 case RTM_RESOLVE: 167 if (gate->sa_family != AF_LINK || 168 gate->sa_len < sizeof(null_sdl)) { 169 log(LOG_DEBUG, "arp_rtrequest: bad gateway value"); 170 break; 171 } 172 SDL(gate)->sdl_type = rt->rt_ifp->if_type; 173 SDL(gate)->sdl_index = rt->rt_ifp->if_index; 174 if (la != 0) 175 break; /* This happens on a route change */ 176 /* 177 * Case 2: This route may come from cloning, or a manual route 178 * add with a LL address. 179 */ 180 R_Malloc(la, struct llinfo_arp *, sizeof(*la)); 181 rt->rt_llinfo = (caddr_t)la; 182 if (la == 0) { 183 log(LOG_DEBUG, "arp_rtrequest: malloc failed\n"); 184 break; 185 } 186 arp_inuse++, arp_allocated++; 187 Bzero(la, sizeof(*la)); 188 la->la_rt = rt; 189 rt->rt_flags |= RTF_LLINFO; 190 insque(la, &llinfo_arp); 191 if (SIN(rt_key(rt))->sin_addr.s_addr == 192 (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) { 193 /* 194 * This test used to be 195 * if (loif.if_flags & IFF_UP) 196 * It allowed local traffic to be forced 197 * through the hardware by configuring the loopback down. 198 * However, it causes problems during network configuration 199 * for boards that can't receive packets they send. 200 * It is now necessary to clear "useloopback" and remove 201 * the route to force traffic out to the hardware. 202 */ 203 rt->rt_expire = 0; 204 Bcopy(((struct arpcom *)rt->rt_ifp)->ac_enaddr, 205 LLADDR(SDL(gate)), SDL(gate)->sdl_alen = 6); 206 if (useloopback) 207 rt->rt_ifp = &loif; 208 209 } 210 break; 211 212 case RTM_DELETE: 213 if (la == 0) 214 break; 215 arp_inuse--; 216 remque(la); 217 rt->rt_llinfo = 0; 218 rt->rt_flags &= ~RTF_LLINFO; 219 if (la->la_hold) 220 m_freem(la->la_hold); 221 Free((caddr_t)la); 222 } 223} 224 225/* 226 * Broadcast an ARP packet, asking who has addr on interface ac. 227 */ 228void 229arpwhohas(ac, addr) 230 register struct arpcom *ac; 231 register struct in_addr *addr; 232{ 233 arprequest(ac, &ac->ac_ipaddr.s_addr, &addr->s_addr, ac->ac_enaddr); 234} 235 236/* 237 * Broadcast an ARP request. Caller specifies: 238 * - arp header source ip address 239 * - arp header target ip address 240 * - arp header source ethernet address 241 */ 242static void 243arprequest(ac, sip, tip, enaddr) 244 register struct arpcom *ac; 245 register u_long *sip, *tip; 246 register u_char *enaddr; 247{ 248 register struct mbuf *m; 249 register struct ether_header *eh; 250 register struct ether_arp *ea; 251 struct sockaddr sa; 252 253 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) 254 return; 255 m->m_len = sizeof(*ea); 256 m->m_pkthdr.len = sizeof(*ea); 257 MH_ALIGN(m, sizeof(*ea)); 258 ea = mtod(m, struct ether_arp *); 259 eh = (struct ether_header *)sa.sa_data; 260 bzero((caddr_t)ea, sizeof (*ea)); 261 bcopy((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost, 262 sizeof(eh->ether_dhost)); 263 eh->ether_type = ETHERTYPE_ARP; /* if_output will swap */ 264 ea->arp_hrd = htons(ARPHRD_ETHER); 265 ea->arp_pro = htons(ETHERTYPE_IP); 266 ea->arp_hln = sizeof(ea->arp_sha); /* hardware address length */ 267 ea->arp_pln = sizeof(ea->arp_spa); /* protocol address length */ 268 ea->arp_op = htons(ARPOP_REQUEST); 269 bcopy((caddr_t)enaddr, (caddr_t)ea->arp_sha, sizeof(ea->arp_sha)); 270 bcopy((caddr_t)sip, (caddr_t)ea->arp_spa, sizeof(ea->arp_spa)); 271 bcopy((caddr_t)tip, (caddr_t)ea->arp_tpa, sizeof(ea->arp_tpa)); 272 sa.sa_family = AF_UNSPEC; 273 sa.sa_len = sizeof(sa); 274 (*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0); 275} 276 277/* 278 * Resolve an IP address into an ethernet address. If success, 279 * desten is filled in. If there is no entry in arptab, 280 * set one up and broadcast a request for the IP address. 281 * Hold onto this mbuf and resend it once the address 282 * is finally resolved. A return value of 1 indicates 283 * that desten has been filled in and the packet should be sent 284 * normally; a 0 return indicates that the packet has been 285 * taken over here, either now or for later transmission. 286 */ 287int 288arpresolve(ac, rt, m, dst, desten) 289 register struct arpcom *ac; 290 register struct rtentry *rt; 291 struct mbuf *m; 292 register struct sockaddr *dst; 293 register u_char *desten; 294{ 295 register struct llinfo_arp *la; 296 struct sockaddr_dl *sdl; 297 298 if (m->m_flags & M_BCAST) { /* broadcast */ 299 bcopy((caddr_t)etherbroadcastaddr, (caddr_t)desten, 300 sizeof(etherbroadcastaddr)); 301 return (1); 302 } 303 if (m->m_flags & M_MCAST) { /* multicast */ 304 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); 305 return(1); 306 } 307 if (rt) 308 la = (struct llinfo_arp *)rt->rt_llinfo; 309 else { 310 if (la = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0)) 311 rt = la->la_rt; 312 } 313 if (la == 0 || rt == 0) { 314 log(LOG_DEBUG, "arpresolve: can't allocate llinfo"); 315 m_freem(m); 316 return (0); 317 } 318 sdl = SDL(rt->rt_gateway); 319 /* 320 * Check the address family and length is valid, the address 321 * is resolved; otherwise, try to resolve. 322 */ 323 if ((rt->rt_expire == 0 || rt->rt_expire > time.tv_sec) && 324 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { 325 bcopy(LLADDR(sdl), desten, sdl->sdl_alen); 326 return 1; 327 } 328 /* 329 * There is an arptab entry, but no ethernet address 330 * response yet. Replace the held mbuf with this 331 * latest one. 332 */ 333 if (la->la_hold) 334 m_freem(la->la_hold); 335 la->la_hold = m; 336 if (rt->rt_expire) { 337 rt->rt_flags &= ~RTF_REJECT; 338 if (la->la_asked == 0 || rt->rt_expire != time.tv_sec) { 339 rt->rt_expire = time.tv_sec; 340 if (la->la_asked++ < arp_maxtries) 341 arpwhohas(ac, &(SIN(dst)->sin_addr)); 342 else { 343 rt->rt_flags |= RTF_REJECT; 344 rt->rt_expire += arpt_down; 345 la->la_asked = 0; 346 } 347 348 } 349 } 350 return (0); 351} 352 353/* 354 * Common length and type checks are done here, 355 * then the protocol-specific routine is called. 356 */ 357void 358arpintr() 359{ 360 register struct mbuf *m; 361 register struct arphdr *ar; 362 int s; 363 364 while (arpintrq.ifq_head) { 365 s = splimp(); 366 IF_DEQUEUE(&arpintrq, m); 367 splx(s); 368 if (m == 0 || (m->m_flags & M_PKTHDR) == 0) 369 panic("arpintr"); 370 if (m->m_len >= sizeof(struct arphdr) && 371 (ar = mtod(m, struct arphdr *)) && 372 ntohs(ar->ar_hrd) == ARPHRD_ETHER && 373 m->m_len >= 374 sizeof(struct arphdr) + 2 * ar->ar_hln + 2 * ar->ar_pln) 375 376 switch (ntohs(ar->ar_pro)) { 377 378 case ETHERTYPE_IP: 379 case ETHERTYPE_IPTRAILERS: 380 in_arpinput(m); 381 continue; 382 } 383 m_freem(m); 384 } 385} 386 387/* 388 * ARP for Internet protocols on 10 Mb/s Ethernet. 389 * Algorithm is that given in RFC 826. 390 * In addition, a sanity check is performed on the sender 391 * protocol address, to catch impersonators. 392 * We no longer handle negotiations for use of trailer protocol: 393 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent 394 * along with IP replies if we wanted trailers sent to us, 395 * and also sent them in response to IP replies. 396 * This allowed either end to announce the desire to receive 397 * trailer packets. 398 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, 399 * but formerly didn't normally send requests. 400 */ 401static void 402in_arpinput(m) 403 struct mbuf *m; 404{ 405 register struct ether_arp *ea; 406 register struct arpcom *ac = (struct arpcom *)m->m_pkthdr.rcvif; 407 struct ether_header *eh; 408 register struct llinfo_arp *la = 0; 409 register struct rtentry *rt; 410 struct in_ifaddr *ia, *maybe_ia = 0; 411 struct sockaddr_dl *sdl; 412 struct sockaddr sa; 413 struct in_addr isaddr, itaddr, myaddr; 414 int op; 415 416 ea = mtod(m, struct ether_arp *); 417 op = ntohs(ea->arp_op); 418 bcopy((caddr_t)ea->arp_spa, (caddr_t)&isaddr, sizeof (isaddr)); 419 bcopy((caddr_t)ea->arp_tpa, (caddr_t)&itaddr, sizeof (itaddr)); 420 for (ia = in_ifaddr; ia; ia = ia->ia_next) 421 if (ia->ia_ifp == &ac->ac_if) { 422 maybe_ia = ia; 423 if ((itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) || 424 (isaddr.s_addr == ia->ia_addr.sin_addr.s_addr)) 425 break; 426 } 427 if (maybe_ia == 0) 428 goto out; 429 myaddr = ia ? ia->ia_addr.sin_addr : maybe_ia->ia_addr.sin_addr; 430 if (!bcmp((caddr_t)ea->arp_sha, (caddr_t)ac->ac_enaddr, 431 sizeof (ea->arp_sha))) 432 goto out; /* it's from me, ignore it. */ 433 if (!bcmp((caddr_t)ea->arp_sha, (caddr_t)etherbroadcastaddr, 434 sizeof (ea->arp_sha))) { 435 log(LOG_ERR, 436 "arp: ether address is broadcast for IP address %x!\n", 437 ntohl(isaddr.s_addr)); 438 goto out; 439 } 440 if (isaddr.s_addr == myaddr.s_addr) { 441 log(LOG_ERR, 442 "duplicate IP address %x!! sent from ethernet address: %s\n", 443 ntohl(isaddr.s_addr), ether_sprintf(ea->arp_sha)); 444 itaddr = myaddr; 445 goto reply; 446 } 447 la = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); 448 if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) { 449 if (sdl->sdl_alen && 450 bcmp((caddr_t)ea->arp_sha, LLADDR(sdl), sdl->sdl_alen)) 451 log(LOG_INFO, "arp info overwritten for %x by %s\n", 452 isaddr.s_addr, ether_sprintf(ea->arp_sha)); 453 bcopy((caddr_t)ea->arp_sha, LLADDR(sdl), 454 sdl->sdl_alen = sizeof(ea->arp_sha)); 455 if (rt->rt_expire) 456 rt->rt_expire = time.tv_sec + arpt_keep; 457 rt->rt_flags &= ~RTF_REJECT; 458 la->la_asked = 0; 459 if (la->la_hold) { 460 (*ac->ac_if.if_output)(&ac->ac_if, la->la_hold, 461 rt_key(rt), rt); 462 la->la_hold = 0; 463 } 464 } 465reply: 466 if (op != ARPOP_REQUEST) { 467 out: 468 m_freem(m); 469 return; 470 } 471 if (itaddr.s_addr == myaddr.s_addr) { 472 /* I am the target */ 473 bcopy((caddr_t)ea->arp_sha, (caddr_t)ea->arp_tha, 474 sizeof(ea->arp_sha)); 475 bcopy((caddr_t)ac->ac_enaddr, (caddr_t)ea->arp_sha, 476 sizeof(ea->arp_sha)); 477 } else { 478 la = arplookup(itaddr.s_addr, 0, SIN_PROXY); 479 if (la == NULL) 480 goto out; 481 rt = la->la_rt; 482 bcopy((caddr_t)ea->arp_sha, (caddr_t)ea->arp_tha, 483 sizeof(ea->arp_sha)); 484 sdl = SDL(rt->rt_gateway); 485 bcopy(LLADDR(sdl), (caddr_t)ea->arp_sha, sizeof(ea->arp_sha)); 486 } 487 488 bcopy((caddr_t)ea->arp_spa, (caddr_t)ea->arp_tpa, sizeof(ea->arp_spa)); 489 bcopy((caddr_t)&itaddr, (caddr_t)ea->arp_spa, sizeof(ea->arp_spa)); 490 ea->arp_op = htons(ARPOP_REPLY); 491 ea->arp_pro = htons(ETHERTYPE_IP); /* let's be sure! */ 492 eh = (struct ether_header *)sa.sa_data; 493 bcopy((caddr_t)ea->arp_tha, (caddr_t)eh->ether_dhost, 494 sizeof(eh->ether_dhost)); 495 eh->ether_type = ETHERTYPE_ARP; 496 sa.sa_family = AF_UNSPEC; 497 sa.sa_len = sizeof(sa); 498 (*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0); 499 return; 500} 501 502/* 503 * Free an arp entry. 504 */ 505static void 506arptfree(la) 507 register struct llinfo_arp *la; 508{ 509 register struct rtentry *rt = la->la_rt; 510 register struct sockaddr_dl *sdl; 511 if (rt == 0) 512 panic("arptfree"); 513 if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) && 514 sdl->sdl_family == AF_LINK) { 515 sdl->sdl_alen = 0; 516 la->la_asked = 0; 517 rt->rt_flags &= ~RTF_REJECT; 518 return; 519 } 520 rtrequest(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt), 521 0, (struct rtentry **)0); 522} 523/* 524 * Lookup or enter a new address in arptab. 525 */ 526static struct llinfo_arp * 527arplookup(addr, create, proxy) 528 u_long addr; 529 int create, proxy; 530{ 531 register struct rtentry *rt; 532 static struct sockaddr_inarp sin = {sizeof(sin), AF_INET }; 533 534 sin.sin_addr.s_addr = addr; 535 sin.sin_other = proxy ? SIN_PROXY : 0; 536 rt = rtalloc1((struct sockaddr *)&sin, create); 537 if (rt == 0) 538 return (0); 539 rt->rt_refcnt--; 540 if ((rt->rt_flags & RTF_GATEWAY) || (rt->rt_flags & RTF_LLINFO) == 0 || 541 rt->rt_gateway->sa_family != AF_LINK) { 542 if (create) 543 log(LOG_DEBUG, "arptnew failed on %x\n", ntohl(addr)); 544 return (0); 545 } 546 return ((struct llinfo_arp *)rt->rt_llinfo); 547} 548 549int 550arpioctl(cmd, data) 551 int cmd; 552 caddr_t data; 553{ 554 return (EOPNOTSUPP); 555} 556