1 /* $NetBSD: if_gre.c,v 1.42 2002/08/14 00:23:27 itojun Exp $ */ 2 /* $FreeBSD$ */ 3 4 /* 5 * Copyright (c) 1998 The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Heiko W.Rupp <hwr@pilhuhn.de> 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 /* 41 * Encapsulate L3 protocols into IP 42 * See RFC 1701 and 1702 for more details. 43 * If_gre is compatible with Cisco GRE tunnels, so you can 44 * have a NetBSD box as the other end of a tunnel interface of a Cisco 45 * router. See gre(4) for more details. 46 * Also supported: IP in IP encaps (proto 55) as of RFC 2004 47 */ 48 49 #include "opt_atalk.h" 50 #include "opt_inet.h" 51 #include "opt_inet6.h" 52 53 #include <sys/param.h> 54 #include <sys/kernel.h> 55 #include <sys/malloc.h> 56 #include <sys/mbuf.h> 57 #include <sys/protosw.h> 58 #include <sys/socket.h> 59 #include <sys/sockio.h> 60 #include <sys/sysctl.h> 61 #include <sys/systm.h> 62 63 #include <net/ethernet.h> 64 #include <net/if.h> 65 #include <net/if_types.h> 66 #include <net/route.h> 67 68 #ifdef INET 69 #include <netinet/in.h> 70 #include <netinet/in_systm.h> 71 #include <netinet/in_var.h> 72 #include <netinet/ip.h> 73 #include <netinet/ip_gre.h> 74 #include <netinet/ip_var.h> 75 #include <netinet/ip_encap.h> 76 #else 77 #error "Huh? if_gre without inet?" 78 #endif 79 80 #include <net/bpf.h> 81 82 #include <net/net_osdep.h> 83 #include <net/if_gre.h> 84 85 /* 86 * It is not easy to calculate the right value for a GRE MTU. 87 * We leave this task to the admin and use the same default that 88 * other vendors use. 89 */ 90 #define GREMTU 1476 91 92 #define GRENAME "gre" 93 94 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation"); 95 96 struct gre_softc_head gre_softc_list; 97 98 static int gre_clone_create(struct if_clone *, int); 99 static void gre_clone_destroy(struct ifnet *); 100 static int gre_ioctl(struct ifnet *, u_long, caddr_t); 101 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *, 102 struct rtentry *rt); 103 104 static struct if_clone gre_cloner = 105 IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy, 0, IF_MAXUNIT); 106 107 static int gre_compute_route(struct gre_softc *sc); 108 109 static void greattach(void); 110 111 #ifdef INET 112 extern struct domain inetdomain; 113 static const struct protosw in_gre_protosw = 114 { SOCK_RAW, &inetdomain, IPPROTO_GRE, PR_ATOMIC|PR_ADDR, 115 (pr_input_t*)gre_input, (pr_output_t*)rip_output, rip_ctlinput, rip_ctloutput, 116 0, 117 0, 0, 0, 0, 118 &rip_usrreqs 119 }; 120 static const struct protosw in_mobile_protosw = 121 { SOCK_RAW, &inetdomain, IPPROTO_MOBILE, PR_ATOMIC|PR_ADDR, 122 (pr_input_t*)gre_mobile_input, (pr_output_t*)rip_output, rip_ctlinput, rip_ctloutput, 123 0, 124 0, 0, 0, 0, 125 &rip_usrreqs 126 }; 127 #endif 128 129 SYSCTL_DECL(_net_link); 130 SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0, 131 "Generic Routing Encapsulation"); 132 #ifndef MAX_GRE_NEST 133 /* 134 * This macro controls the default upper limitation on nesting of gre tunnels. 135 * Since, setting a large value to this macro with a careless configuration 136 * may introduce system crash, we don't allow any nestings by default. 137 * If you need to configure nested gre tunnels, you can define this macro 138 * in your kernel configuration file. However, if you do so, please be 139 * careful to configure the tunnels so that it won't make a loop. 140 */ 141 #define MAX_GRE_NEST 1 142 #endif 143 static int max_gre_nesting = MAX_GRE_NEST; 144 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW, 145 &max_gre_nesting, 0, "Max nested tunnels"); 146 147 /* ARGSUSED */ 148 static void 149 greattach(void) 150 { 151 152 LIST_INIT(&gre_softc_list); 153 if_clone_attach(&gre_cloner); 154 } 155 156 static int 157 gre_clone_create(ifc, unit) 158 struct if_clone *ifc; 159 int unit; 160 { 161 struct gre_softc *sc; 162 163 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK); 164 memset(sc, 0, sizeof(struct gre_softc)); 165 166 if_initname(&sc->sc_if, ifc->ifc_name, unit); 167 sc->sc_if.if_softc = sc; 168 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN; 169 sc->sc_if.if_type = IFT_TUNNEL; 170 sc->sc_if.if_addrlen = 0; 171 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 172 sc->sc_if.if_mtu = GREMTU; 173 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 174 sc->sc_if.if_output = gre_output; 175 sc->sc_if.if_ioctl = gre_ioctl; 176 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 177 sc->g_proto = IPPROTO_GRE; 178 sc->sc_if.if_flags |= IFF_LINK0; 179 sc->encap = NULL; 180 sc->called = 0; 181 if_attach(&sc->sc_if); 182 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 183 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 184 return (0); 185 } 186 187 static void 188 gre_clone_destroy(ifp) 189 struct ifnet *ifp; 190 { 191 struct gre_softc *sc = ifp->if_softc; 192 193 #ifdef INET 194 if (sc->encap != NULL) 195 encap_detach(sc->encap); 196 #endif 197 LIST_REMOVE(sc, sc_list); 198 bpfdetach(ifp); 199 if_detach(ifp); 200 free(sc, M_GRE); 201 } 202 203 /* 204 * The output routine. Takes a packet and encapsulates it in the protocol 205 * given by sc->g_proto. See also RFC 1701 and RFC 2004 206 */ 207 static int 208 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 209 struct rtentry *rt) 210 { 211 int error = 0; 212 struct gre_softc *sc = ifp->if_softc; 213 struct greip *gh; 214 struct ip *ip; 215 u_char osrc; 216 u_short etype = 0; 217 struct mobile_h mob_h; 218 219 /* 220 * gre may cause infinite recursion calls when misconfigured. 221 * We'll prevent this by introducing upper limit. 222 */ 223 if (++(sc->called) > max_gre_nesting) { 224 printf("%s: gre_output: recursively called too many " 225 "times(%d)\n", if_name(&sc->sc_if), sc->called); 226 m_freem(m); 227 error = EIO; /* is there better errno? */ 228 goto end; 229 } 230 231 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 232 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 233 m_freem(m); 234 error = ENETDOWN; 235 goto end; 236 } 237 238 gh = NULL; 239 ip = NULL; 240 osrc = 0; 241 242 if (ifp->if_bpf) { 243 u_int32_t af = dst->sa_family; 244 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m); 245 } 246 247 m->m_flags &= ~(M_BCAST|M_MCAST); 248 249 if (sc->g_proto == IPPROTO_MOBILE) { 250 if (dst->sa_family == AF_INET) { 251 struct mbuf *m0; 252 int msiz; 253 254 ip = mtod(m, struct ip *); 255 256 /* 257 * RFC2004 specifies that fragmented diagrams shouldn't 258 * be encapsulated. 259 */ 260 if ((ip->ip_off & IP_MF) != 0) { 261 _IF_DROP(&ifp->if_snd); 262 m_freem(m); 263 error = EINVAL; /* is there better errno? */ 264 goto end; 265 } 266 memset(&mob_h, 0, MOB_H_SIZ_L); 267 mob_h.proto = (ip->ip_p) << 8; 268 mob_h.odst = ip->ip_dst.s_addr; 269 ip->ip_dst.s_addr = sc->g_dst.s_addr; 270 271 /* 272 * If the packet comes from our host, we only change 273 * the destination address in the IP header. 274 * Else we also need to save and change the source 275 */ 276 if (in_hosteq(ip->ip_src, sc->g_src)) { 277 msiz = MOB_H_SIZ_S; 278 } else { 279 mob_h.proto |= MOB_H_SBIT; 280 mob_h.osrc = ip->ip_src.s_addr; 281 ip->ip_src.s_addr = sc->g_src.s_addr; 282 msiz = MOB_H_SIZ_L; 283 } 284 mob_h.proto = htons(mob_h.proto); 285 mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz); 286 287 if ((m->m_data - msiz) < m->m_pktdat) { 288 /* need new mbuf */ 289 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 290 if (m0 == NULL) { 291 _IF_DROP(&ifp->if_snd); 292 m_freem(m); 293 error = ENOBUFS; 294 goto end; 295 } 296 m0->m_next = m; 297 m->m_data += sizeof(struct ip); 298 m->m_len -= sizeof(struct ip); 299 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 300 m0->m_len = msiz + sizeof(struct ip); 301 m0->m_data += max_linkhdr; 302 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 303 sizeof(struct ip)); 304 m = m0; 305 } else { /* we have some space left in the old one */ 306 m->m_data -= msiz; 307 m->m_len += msiz; 308 m->m_pkthdr.len += msiz; 309 bcopy(ip, mtod(m, caddr_t), 310 sizeof(struct ip)); 311 } 312 ip = mtod(m, struct ip *); 313 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 314 ip->ip_len = ntohs(ip->ip_len) + msiz; 315 } else { /* AF_INET */ 316 _IF_DROP(&ifp->if_snd); 317 m_freem(m); 318 error = EINVAL; 319 goto end; 320 } 321 } else if (sc->g_proto == IPPROTO_GRE) { 322 switch (dst->sa_family) { 323 case AF_INET: 324 ip = mtod(m, struct ip *); 325 etype = ETHERTYPE_IP; 326 break; 327 #ifdef NETATALK 328 case AF_APPLETALK: 329 etype = ETHERTYPE_ATALK; 330 break; 331 #endif 332 default: 333 _IF_DROP(&ifp->if_snd); 334 m_freem(m); 335 error = EAFNOSUPPORT; 336 goto end; 337 } 338 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 339 } else { 340 _IF_DROP(&ifp->if_snd); 341 m_freem(m); 342 error = EINVAL; 343 goto end; 344 } 345 346 if (m == NULL) { /* impossible */ 347 _IF_DROP(&ifp->if_snd); 348 error = ENOBUFS; 349 goto end; 350 } 351 352 gh = mtod(m, struct greip *); 353 if (sc->g_proto == IPPROTO_GRE) { 354 /* we don't have any GRE flags for now */ 355 356 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 357 gh->gi_ptype = htons(etype); 358 } 359 360 gh->gi_pr = sc->g_proto; 361 if (sc->g_proto != IPPROTO_MOBILE) { 362 gh->gi_src = sc->g_src; 363 gh->gi_dst = sc->g_dst; 364 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 365 ((struct ip*)gh)->ip_ttl = GRE_TTL; 366 ((struct ip*)gh)->ip_tos = ip->ip_tos; 367 ((struct ip*)gh)->ip_id = ip->ip_id; 368 gh->gi_len = m->m_pkthdr.len; 369 } 370 371 ifp->if_opackets++; 372 ifp->if_obytes += m->m_pkthdr.len; 373 /* send it off */ 374 error = ip_output(m, NULL, &sc->route, 0, NULL, NULL); 375 end: 376 sc->called = 0; 377 if (error) 378 ifp->if_oerrors++; 379 return (error); 380 } 381 382 static int 383 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 384 { 385 struct ifreq *ifr = (struct ifreq *)data; 386 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 387 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 388 struct gre_softc *sc = ifp->if_softc; 389 int s; 390 struct sockaddr_in si; 391 struct sockaddr *sa = NULL; 392 int error; 393 struct sockaddr_in sp, sm, dp, dm; 394 395 error = 0; 396 397 s = splnet(); 398 switch (cmd) { 399 case SIOCSIFADDR: 400 ifp->if_flags |= IFF_UP; 401 break; 402 case SIOCSIFDSTADDR: 403 break; 404 case SIOCSIFFLAGS: 405 if ((error = suser(curthread)) != 0) 406 break; 407 if ((ifr->ifr_flags & IFF_LINK0) != 0) 408 sc->g_proto = IPPROTO_GRE; 409 else 410 sc->g_proto = IPPROTO_MOBILE; 411 goto recompute; 412 case SIOCSIFMTU: 413 if ((error = suser(curthread)) != 0) 414 break; 415 if (ifr->ifr_mtu < 576) { 416 error = EINVAL; 417 break; 418 } 419 ifp->if_mtu = ifr->ifr_mtu; 420 break; 421 case SIOCGIFMTU: 422 ifr->ifr_mtu = sc->sc_if.if_mtu; 423 break; 424 case SIOCADDMULTI: 425 case SIOCDELMULTI: 426 if ((error = suser(curthread)) != 0) 427 break; 428 if (ifr == 0) { 429 error = EAFNOSUPPORT; 430 break; 431 } 432 switch (ifr->ifr_addr.sa_family) { 433 #ifdef INET 434 case AF_INET: 435 break; 436 #endif 437 default: 438 error = EAFNOSUPPORT; 439 break; 440 } 441 break; 442 case GRESPROTO: 443 if ((error = suser(curthread)) != 0) 444 break; 445 sc->g_proto = ifr->ifr_flags; 446 switch (sc->g_proto) { 447 case IPPROTO_GRE: 448 ifp->if_flags |= IFF_LINK0; 449 break; 450 case IPPROTO_MOBILE: 451 ifp->if_flags &= ~IFF_LINK0; 452 break; 453 default: 454 error = EPROTONOSUPPORT; 455 break; 456 } 457 goto recompute; 458 case GREGPROTO: 459 ifr->ifr_flags = sc->g_proto; 460 break; 461 case GRESADDRS: 462 case GRESADDRD: 463 if ((error = suser(curthread)) != 0) 464 break; 465 /* 466 * set tunnel endpoints, compute a less specific route 467 * to the remote end and mark if as up 468 */ 469 sa = &ifr->ifr_addr; 470 if (cmd == GRESADDRS) 471 sc->g_src = (satosin(sa))->sin_addr; 472 if (cmd == GRESADDRD) 473 sc->g_dst = (satosin(sa))->sin_addr; 474 recompute: 475 #ifdef INET 476 if (sc->encap != NULL) { 477 encap_detach(sc->encap); 478 sc->encap = NULL; 479 } 480 #endif 481 if ((sc->g_src.s_addr != INADDR_ANY) && 482 (sc->g_dst.s_addr != INADDR_ANY)) { 483 bzero(&sp, sizeof(sp)); 484 bzero(&sm, sizeof(sm)); 485 bzero(&dp, sizeof(dp)); 486 bzero(&dm, sizeof(dm)); 487 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 488 sizeof(struct sockaddr_in); 489 sp.sin_family = sm.sin_family = dp.sin_family = 490 dm.sin_family = AF_INET; 491 sp.sin_addr = sc->g_src; 492 dp.sin_addr = sc->g_dst; 493 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 494 INADDR_BROADCAST; 495 #ifdef INET 496 sc->encap = encap_attach(AF_INET, sc->g_proto, 497 sintosa(&sp), sintosa(&sm), sintosa(&dp), 498 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 499 &in_gre_protosw : &in_mobile_protosw, sc); 500 if (sc->encap == NULL) 501 printf("%s: unable to attach encap\n", 502 if_name(&sc->sc_if)); 503 #endif 504 if (sc->route.ro_rt != 0) /* free old route */ 505 RTFREE(sc->route.ro_rt); 506 if (gre_compute_route(sc) == 0) 507 ifp->if_flags |= IFF_RUNNING; 508 else 509 ifp->if_flags &= ~IFF_RUNNING; 510 } 511 break; 512 case GREGADDRS: 513 memset(&si, 0, sizeof(si)); 514 si.sin_family = AF_INET; 515 si.sin_len = sizeof(struct sockaddr_in); 516 si.sin_addr.s_addr = sc->g_src.s_addr; 517 sa = sintosa(&si); 518 ifr->ifr_addr = *sa; 519 break; 520 case GREGADDRD: 521 memset(&si, 0, sizeof(si)); 522 si.sin_family = AF_INET; 523 si.sin_len = sizeof(struct sockaddr_in); 524 si.sin_addr.s_addr = sc->g_dst.s_addr; 525 sa = sintosa(&si); 526 ifr->ifr_addr = *sa; 527 break; 528 case SIOCSIFPHYADDR: 529 if ((error = suser(curthread)) != 0) 530 break; 531 if (aifr->ifra_addr.sin_family != AF_INET || 532 aifr->ifra_dstaddr.sin_family != AF_INET) { 533 error = EAFNOSUPPORT; 534 break; 535 } 536 if (aifr->ifra_addr.sin_len != sizeof(si) || 537 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 538 error = EINVAL; 539 break; 540 } 541 sc->g_src = aifr->ifra_addr.sin_addr; 542 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 543 goto recompute; 544 case SIOCSLIFPHYADDR: 545 if ((error = suser(curthread)) != 0) 546 break; 547 if (lifr->addr.ss_family != AF_INET || 548 lifr->dstaddr.ss_family != AF_INET) { 549 error = EAFNOSUPPORT; 550 break; 551 } 552 if (lifr->addr.ss_len != sizeof(si) || 553 lifr->dstaddr.ss_len != sizeof(si)) { 554 error = EINVAL; 555 break; 556 } 557 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 558 sc->g_dst = 559 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 560 goto recompute; 561 case SIOCDIFPHYADDR: 562 if ((error = suser(curthread)) != 0) 563 break; 564 sc->g_src.s_addr = INADDR_ANY; 565 sc->g_dst.s_addr = INADDR_ANY; 566 goto recompute; 567 case SIOCGLIFPHYADDR: 568 if (sc->g_src.s_addr == INADDR_ANY || 569 sc->g_dst.s_addr == INADDR_ANY) { 570 error = EADDRNOTAVAIL; 571 break; 572 } 573 memset(&si, 0, sizeof(si)); 574 si.sin_family = AF_INET; 575 si.sin_len = sizeof(struct sockaddr_in); 576 si.sin_addr.s_addr = sc->g_src.s_addr; 577 memcpy(&lifr->addr, &si, sizeof(si)); 578 si.sin_addr.s_addr = sc->g_dst.s_addr; 579 memcpy(&lifr->dstaddr, &si, sizeof(si)); 580 break; 581 case SIOCGIFPSRCADDR: 582 #ifdef INET6 583 case SIOCGIFPSRCADDR_IN6: 584 #endif 585 if (sc->g_src.s_addr == INADDR_ANY) { 586 error = EADDRNOTAVAIL; 587 break; 588 } 589 memset(&si, 0, sizeof(si)); 590 si.sin_family = AF_INET; 591 si.sin_len = sizeof(struct sockaddr_in); 592 si.sin_addr.s_addr = sc->g_src.s_addr; 593 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 594 break; 595 case SIOCGIFPDSTADDR: 596 #ifdef INET6 597 case SIOCGIFPDSTADDR_IN6: 598 #endif 599 if (sc->g_dst.s_addr == INADDR_ANY) { 600 error = EADDRNOTAVAIL; 601 break; 602 } 603 memset(&si, 0, sizeof(si)); 604 si.sin_family = AF_INET; 605 si.sin_len = sizeof(struct sockaddr_in); 606 si.sin_addr.s_addr = sc->g_dst.s_addr; 607 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 608 break; 609 default: 610 error = EINVAL; 611 break; 612 } 613 614 splx(s); 615 return (error); 616 } 617 618 /* 619 * computes a route to our destination that is not the one 620 * which would be taken by ip_output(), as this one will loop back to 621 * us. If the interface is p2p as a--->b, then a routing entry exists 622 * If we now send a packet to b (e.g. ping b), this will come down here 623 * gets src=a, dst=b tacked on and would from ip_ouput() sent back to 624 * if_gre. 625 * Goal here is to compute a route to b that is less specific than 626 * a-->b. We know that this one exists as in normal operation we have 627 * at least a default route which matches. 628 */ 629 static int 630 gre_compute_route(struct gre_softc *sc) 631 { 632 struct route *ro; 633 u_int32_t a, b, c; 634 635 ro = &sc->route; 636 637 memset(ro, 0, sizeof(struct route)); 638 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 639 ro->ro_dst.sa_family = AF_INET; 640 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 641 642 /* 643 * toggle last bit, so our interface is not found, but a less 644 * specific route. I'd rather like to specify a shorter mask, 645 * but this is not possible. Should work though. XXX 646 * there is a simpler way ... 647 */ 648 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 649 a = ntohl(sc->g_dst.s_addr); 650 b = a & 0x01; 651 c = a & 0xfffffffe; 652 b = b ^ 0x01; 653 a = b | c; 654 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 655 = htonl(a); 656 } 657 658 #ifdef DIAGNOSTIC 659 printf("%s: searching a route to %s", if_name(&sc->sc_if), 660 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 661 #endif 662 663 rtalloc(ro); 664 665 /* 666 * check if this returned a route at all and this route is no 667 * recursion to ourself 668 */ 669 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 670 #ifdef DIAGNOSTIC 671 if (ro->ro_rt == NULL) 672 printf(" - no route found!\n"); 673 else 674 printf(" - route loops back to ourself!\n"); 675 #endif 676 return EADDRNOTAVAIL; 677 } 678 679 /* 680 * now change it back - else ip_output will just drop 681 * the route and search one to this interface ... 682 */ 683 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 684 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 685 686 #ifdef DIAGNOSTIC 687 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 688 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 689 printf("\n"); 690 #endif 691 692 return 0; 693 } 694 695 /* 696 * do a checksum of a buffer - much like in_cksum, which operates on 697 * mbufs. 698 */ 699 u_short 700 gre_in_cksum(u_short *p, u_int len) 701 { 702 u_int sum = 0; 703 int nwords = len >> 1; 704 705 while (nwords-- != 0) 706 sum += *p++; 707 708 if (len & 1) { 709 union { 710 u_short w; 711 u_char c[2]; 712 } u; 713 u.c[0] = *(u_char *)p; 714 u.c[1] = 0; 715 sum += u.w; 716 } 717 718 /* end-around-carry */ 719 sum = (sum >> 16) + (sum & 0xffff); 720 sum += (sum >> 16); 721 return (~sum); 722 } 723 724 static int 725 gremodevent(module_t mod, int type, void *data) 726 { 727 728 switch (type) { 729 case MOD_LOAD: 730 greattach(); 731 break; 732 case MOD_UNLOAD: 733 if_clone_detach(&gre_cloner); 734 735 while (!LIST_EMPTY(&gre_softc_list)) 736 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 737 break; 738 } 739 return 0; 740 } 741 742 static moduledata_t gre_mod = { 743 "if_gre", 744 gremodevent, 745 0 746 }; 747 748 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 749 MODULE_VERSION(if_gre, 1); 750