if_gre.c revision 125020
1/* $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $ */ 2/* $FreeBSD: head/sys/net/if_gre.c 125020 2004-01-26 12:21:59Z sobomax $ */ 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 94static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation"); 95 96struct gre_softc_head gre_softc_list; 97 98static int gre_clone_create(struct if_clone *, int); 99static void gre_clone_destroy(struct ifnet *); 100static int gre_ioctl(struct ifnet *, u_long, caddr_t); 101static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *, 102 struct rtentry *rt); 103 104static struct if_clone gre_cloner = 105 IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy, 0, IF_MAXUNIT); 106 107static int gre_compute_route(struct gre_softc *sc); 108 109static void greattach(void); 110 111#ifdef INET 112extern struct domain inetdomain; 113static 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}; 120static 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 129SYSCTL_DECL(_net_link); 130SYSCTL_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 143static int max_gre_nesting = MAX_GRE_NEST; 144SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW, 145 &max_gre_nesting, 0, "Max nested tunnels"); 146 147/* ARGSUSED */ 148static void 149greattach(void) 150{ 151 152 LIST_INIT(&gre_softc_list); 153 if_clone_attach(&gre_cloner); 154} 155 156static int 157gre_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 187static void 188gre_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 */ 207static int 208gre_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_int16_t etype = 0; 216 struct mobile_h mob_h; 217 218 /* 219 * gre may cause infinite recursion calls when misconfigured. 220 * We'll prevent this by introducing upper limit. 221 */ 222 if (++(sc->called) > max_gre_nesting) { 223 printf("%s: gre_output: recursively called too many " 224 "times(%d)\n", if_name(&sc->sc_if), sc->called); 225 m_freem(m); 226 error = EIO; /* is there better errno? */ 227 goto end; 228 } 229 230 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 231 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 232 m_freem(m); 233 error = ENETDOWN; 234 goto end; 235 } 236 237 gh = NULL; 238 ip = NULL; 239 240 if (ifp->if_bpf) { 241 u_int32_t af = dst->sa_family; 242 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m); 243 } 244 245 m->m_flags &= ~(M_BCAST|M_MCAST); 246 247 if (sc->g_proto == IPPROTO_MOBILE) { 248 if (dst->sa_family == AF_INET) { 249 struct mbuf *m0; 250 int msiz; 251 252 ip = mtod(m, struct ip *); 253 254 /* 255 * RFC2004 specifies that fragmented diagrams shouldn't 256 * be encapsulated. 257 */ 258 if ((ip->ip_off & IP_MF) != 0) { 259 _IF_DROP(&ifp->if_snd); 260 m_freem(m); 261 error = EINVAL; /* is there better errno? */ 262 goto end; 263 } 264 memset(&mob_h, 0, MOB_H_SIZ_L); 265 mob_h.proto = (ip->ip_p) << 8; 266 mob_h.odst = ip->ip_dst.s_addr; 267 ip->ip_dst.s_addr = sc->g_dst.s_addr; 268 269 /* 270 * If the packet comes from our host, we only change 271 * the destination address in the IP header. 272 * Else we also need to save and change the source 273 */ 274 if (in_hosteq(ip->ip_src, sc->g_src)) { 275 msiz = MOB_H_SIZ_S; 276 } else { 277 mob_h.proto |= MOB_H_SBIT; 278 mob_h.osrc = ip->ip_src.s_addr; 279 ip->ip_src.s_addr = sc->g_src.s_addr; 280 msiz = MOB_H_SIZ_L; 281 } 282 mob_h.proto = htons(mob_h.proto); 283 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz); 284 285 if ((m->m_data - msiz) < m->m_pktdat) { 286 /* need new mbuf */ 287 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 288 if (m0 == NULL) { 289 _IF_DROP(&ifp->if_snd); 290 m_freem(m); 291 error = ENOBUFS; 292 goto end; 293 } 294 m0->m_next = m; 295 m->m_data += sizeof(struct ip); 296 m->m_len -= sizeof(struct ip); 297 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 298 m0->m_len = msiz + sizeof(struct ip); 299 m0->m_data += max_linkhdr; 300 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 301 sizeof(struct ip)); 302 m = m0; 303 } else { /* we have some space left in the old one */ 304 m->m_data -= msiz; 305 m->m_len += msiz; 306 m->m_pkthdr.len += msiz; 307 bcopy(ip, mtod(m, caddr_t), 308 sizeof(struct ip)); 309 } 310 ip = mtod(m, struct ip *); 311 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 312 ip->ip_len = ntohs(ip->ip_len) + msiz; 313 } else { /* AF_INET */ 314 _IF_DROP(&ifp->if_snd); 315 m_freem(m); 316 error = EINVAL; 317 goto end; 318 } 319 } else if (sc->g_proto == IPPROTO_GRE) { 320 switch (dst->sa_family) { 321 case AF_INET: 322 ip = mtod(m, struct ip *); 323 etype = ETHERTYPE_IP; 324 break; 325#ifdef NETATALK 326 case AF_APPLETALK: 327 etype = ETHERTYPE_ATALK; 328 break; 329#endif 330 default: 331 _IF_DROP(&ifp->if_snd); 332 m_freem(m); 333 error = EAFNOSUPPORT; 334 goto end; 335 } 336 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 337 } else { 338 _IF_DROP(&ifp->if_snd); 339 m_freem(m); 340 error = EINVAL; 341 goto end; 342 } 343 344 if (m == NULL) { /* impossible */ 345 _IF_DROP(&ifp->if_snd); 346 error = ENOBUFS; 347 goto end; 348 } 349 350 gh = mtod(m, struct greip *); 351 if (sc->g_proto == IPPROTO_GRE) { 352 /* we don't have any GRE flags for now */ 353 354 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 355 gh->gi_ptype = htons(etype); 356 } 357 358 gh->gi_pr = sc->g_proto; 359 if (sc->g_proto != IPPROTO_MOBILE) { 360 gh->gi_src = sc->g_src; 361 gh->gi_dst = sc->g_dst; 362 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 363 ((struct ip*)gh)->ip_ttl = GRE_TTL; 364 ((struct ip*)gh)->ip_tos = ip->ip_tos; 365 ((struct ip*)gh)->ip_id = ip->ip_id; 366 gh->gi_len = htons(m->m_pkthdr.len); 367 } 368 369 ifp->if_opackets++; 370 ifp->if_obytes += m->m_pkthdr.len; 371 /* send it off */ 372 error = ip_output(m, NULL, &sc->route, 0, 373 (struct ip_moptions *)NULL, (struct inpcb *)NULL); 374 end: 375 sc->called = 0; 376 if (error) 377 ifp->if_oerrors++; 378 return (error); 379} 380 381static int 382gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 383{ 384 struct ifreq *ifr = (struct ifreq *)data; 385 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 386 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 387 struct gre_softc *sc = ifp->if_softc; 388 int s; 389 struct sockaddr_in si; 390 struct sockaddr *sa = NULL; 391 int error; 392 struct sockaddr_in sp, sm, dp, dm; 393 394 error = 0; 395 396 s = splnet(); 397 switch (cmd) { 398 case SIOCSIFADDR: 399 ifp->if_flags |= IFF_UP; 400 break; 401 case SIOCSIFDSTADDR: 402 break; 403 case SIOCSIFFLAGS: 404 if ((error = suser(curthread)) != 0) 405 break; 406 if ((ifr->ifr_flags & IFF_LINK0) != 0) 407 sc->g_proto = IPPROTO_GRE; 408 else 409 sc->g_proto = IPPROTO_MOBILE; 410 goto recompute; 411 case SIOCSIFMTU: 412 if ((error = suser(curthread)) != 0) 413 break; 414 if (ifr->ifr_mtu < 576) { 415 error = EINVAL; 416 break; 417 } 418 ifp->if_mtu = ifr->ifr_mtu; 419 break; 420 case SIOCGIFMTU: 421 ifr->ifr_mtu = sc->sc_if.if_mtu; 422 break; 423 case SIOCADDMULTI: 424 case SIOCDELMULTI: 425 if ((error = suser(curthread)) != 0) 426 break; 427 if (ifr == 0) { 428 error = EAFNOSUPPORT; 429 break; 430 } 431 switch (ifr->ifr_addr.sa_family) { 432#ifdef INET 433 case AF_INET: 434 break; 435#endif 436 default: 437 error = EAFNOSUPPORT; 438 break; 439 } 440 break; 441 case GRESPROTO: 442 if ((error = suser(curthread)) != 0) 443 break; 444 sc->g_proto = ifr->ifr_flags; 445 switch (sc->g_proto) { 446 case IPPROTO_GRE: 447 ifp->if_flags |= IFF_LINK0; 448 break; 449 case IPPROTO_MOBILE: 450 ifp->if_flags &= ~IFF_LINK0; 451 break; 452 default: 453 error = EPROTONOSUPPORT; 454 break; 455 } 456 goto recompute; 457 case GREGPROTO: 458 ifr->ifr_flags = sc->g_proto; 459 break; 460 case GRESADDRS: 461 case GRESADDRD: 462 if ((error = suser(curthread)) != 0) 463 break; 464 /* 465 * set tunnel endpoints, compute a less specific route 466 * to the remote end and mark if as up 467 */ 468 sa = &ifr->ifr_addr; 469 if (cmd == GRESADDRS) 470 sc->g_src = (satosin(sa))->sin_addr; 471 if (cmd == GRESADDRD) 472 sc->g_dst = (satosin(sa))->sin_addr; 473 recompute: 474#ifdef INET 475 if (sc->encap != NULL) { 476 encap_detach(sc->encap); 477 sc->encap = NULL; 478 } 479#endif 480 if ((sc->g_src.s_addr != INADDR_ANY) && 481 (sc->g_dst.s_addr != INADDR_ANY)) { 482 bzero(&sp, sizeof(sp)); 483 bzero(&sm, sizeof(sm)); 484 bzero(&dp, sizeof(dp)); 485 bzero(&dm, sizeof(dm)); 486 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 487 sizeof(struct sockaddr_in); 488 sp.sin_family = sm.sin_family = dp.sin_family = 489 dm.sin_family = AF_INET; 490 sp.sin_addr = sc->g_src; 491 dp.sin_addr = sc->g_dst; 492 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 493 INADDR_BROADCAST; 494#ifdef INET 495 sc->encap = encap_attach(AF_INET, sc->g_proto, 496 sintosa(&sp), sintosa(&sm), sintosa(&dp), 497 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 498 &in_gre_protosw : &in_mobile_protosw, sc); 499 if (sc->encap == NULL) 500 printf("%s: unable to attach encap\n", 501 if_name(&sc->sc_if)); 502#endif 503 if (sc->route.ro_rt != 0) /* free old route */ 504 RTFREE(sc->route.ro_rt); 505 if (gre_compute_route(sc) == 0) 506 ifp->if_flags |= IFF_RUNNING; 507 else 508 ifp->if_flags &= ~IFF_RUNNING; 509 } 510 break; 511 case GREGADDRS: 512 memset(&si, 0, sizeof(si)); 513 si.sin_family = AF_INET; 514 si.sin_len = sizeof(struct sockaddr_in); 515 si.sin_addr.s_addr = sc->g_src.s_addr; 516 sa = sintosa(&si); 517 ifr->ifr_addr = *sa; 518 break; 519 case GREGADDRD: 520 memset(&si, 0, sizeof(si)); 521 si.sin_family = AF_INET; 522 si.sin_len = sizeof(struct sockaddr_in); 523 si.sin_addr.s_addr = sc->g_dst.s_addr; 524 sa = sintosa(&si); 525 ifr->ifr_addr = *sa; 526 break; 527 case SIOCSIFPHYADDR: 528 if ((error = suser(curthread)) != 0) 529 break; 530 if (aifr->ifra_addr.sin_family != AF_INET || 531 aifr->ifra_dstaddr.sin_family != AF_INET) { 532 error = EAFNOSUPPORT; 533 break; 534 } 535 if (aifr->ifra_addr.sin_len != sizeof(si) || 536 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 537 error = EINVAL; 538 break; 539 } 540 sc->g_src = aifr->ifra_addr.sin_addr; 541 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 542 goto recompute; 543 case SIOCSLIFPHYADDR: 544 if ((error = suser(curthread)) != 0) 545 break; 546 if (lifr->addr.ss_family != AF_INET || 547 lifr->dstaddr.ss_family != AF_INET) { 548 error = EAFNOSUPPORT; 549 break; 550 } 551 if (lifr->addr.ss_len != sizeof(si) || 552 lifr->dstaddr.ss_len != sizeof(si)) { 553 error = EINVAL; 554 break; 555 } 556 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 557 sc->g_dst = 558 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 559 goto recompute; 560 case SIOCDIFPHYADDR: 561 if ((error = suser(curthread)) != 0) 562 break; 563 sc->g_src.s_addr = INADDR_ANY; 564 sc->g_dst.s_addr = INADDR_ANY; 565 goto recompute; 566 case SIOCGLIFPHYADDR: 567 if (sc->g_src.s_addr == INADDR_ANY || 568 sc->g_dst.s_addr == INADDR_ANY) { 569 error = EADDRNOTAVAIL; 570 break; 571 } 572 memset(&si, 0, sizeof(si)); 573 si.sin_family = AF_INET; 574 si.sin_len = sizeof(struct sockaddr_in); 575 si.sin_addr.s_addr = sc->g_src.s_addr; 576 memcpy(&lifr->addr, &si, sizeof(si)); 577 si.sin_addr.s_addr = sc->g_dst.s_addr; 578 memcpy(&lifr->dstaddr, &si, sizeof(si)); 579 break; 580 case SIOCGIFPSRCADDR: 581#ifdef INET6 582 case SIOCGIFPSRCADDR_IN6: 583#endif 584 if (sc->g_src.s_addr == INADDR_ANY) { 585 error = EADDRNOTAVAIL; 586 break; 587 } 588 memset(&si, 0, sizeof(si)); 589 si.sin_family = AF_INET; 590 si.sin_len = sizeof(struct sockaddr_in); 591 si.sin_addr.s_addr = sc->g_src.s_addr; 592 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 593 break; 594 case SIOCGIFPDSTADDR: 595#ifdef INET6 596 case SIOCGIFPDSTADDR_IN6: 597#endif 598 if (sc->g_dst.s_addr == INADDR_ANY) { 599 error = EADDRNOTAVAIL; 600 break; 601 } 602 memset(&si, 0, sizeof(si)); 603 si.sin_family = AF_INET; 604 si.sin_len = sizeof(struct sockaddr_in); 605 si.sin_addr.s_addr = sc->g_dst.s_addr; 606 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 607 break; 608 default: 609 error = EINVAL; 610 break; 611 } 612 613 splx(s); 614 return (error); 615} 616 617/* 618 * computes a route to our destination that is not the one 619 * which would be taken by ip_output(), as this one will loop back to 620 * us. If the interface is p2p as a--->b, then a routing entry exists 621 * If we now send a packet to b (e.g. ping b), this will come down here 622 * gets src=a, dst=b tacked on and would from ip_output() sent back to 623 * if_gre. 624 * Goal here is to compute a route to b that is less specific than 625 * a-->b. We know that this one exists as in normal operation we have 626 * at least a default route which matches. 627 */ 628static int 629gre_compute_route(struct gre_softc *sc) 630{ 631 struct route *ro; 632 u_int32_t a, b, c; 633 634 ro = &sc->route; 635 636 memset(ro, 0, sizeof(struct route)); 637 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 638 ro->ro_dst.sa_family = AF_INET; 639 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 640 641 /* 642 * toggle last bit, so our interface is not found, but a less 643 * specific route. I'd rather like to specify a shorter mask, 644 * but this is not possible. Should work though. XXX 645 * there is a simpler way ... 646 */ 647 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 648 a = ntohl(sc->g_dst.s_addr); 649 b = a & 0x01; 650 c = a & 0xfffffffe; 651 b = b ^ 0x01; 652 a = b | c; 653 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 654 = htonl(a); 655 } 656 657#ifdef DIAGNOSTIC 658 printf("%s: searching for a route to %s", if_name(&sc->sc_if), 659 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 660#endif 661 662 rtalloc(ro); 663 664 /* 665 * check if this returned a route at all and this route is no 666 * recursion to ourself 667 */ 668 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 669#ifdef DIAGNOSTIC 670 if (ro->ro_rt == NULL) 671 printf(" - no route found!\n"); 672 else 673 printf(" - route loops back to ourself!\n"); 674#endif 675 return EADDRNOTAVAIL; 676 } 677 678 /* 679 * now change it back - else ip_output will just drop 680 * the route and search one to this interface ... 681 */ 682 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 683 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 684 685#ifdef DIAGNOSTIC 686 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 687 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 688 printf("\n"); 689#endif 690 691 return 0; 692} 693 694/* 695 * do a checksum of a buffer - much like in_cksum, which operates on 696 * mbufs. 697 */ 698u_int16_t 699gre_in_cksum(u_int16_t *p, u_int len) 700{ 701 u_int32_t sum = 0; 702 int nwords = len >> 1; 703 704 while (nwords-- != 0) 705 sum += *p++; 706 707 if (len & 1) { 708 union { 709 u_short w; 710 u_char c[2]; 711 } u; 712 u.c[0] = *(u_char *)p; 713 u.c[1] = 0; 714 sum += u.w; 715 } 716 717 /* end-around-carry */ 718 sum = (sum >> 16) + (sum & 0xffff); 719 sum += (sum >> 16); 720 return (~sum); 721} 722 723static int 724gremodevent(module_t mod, int type, void *data) 725{ 726 727 switch (type) { 728 case MOD_LOAD: 729 greattach(); 730 break; 731 case MOD_UNLOAD: 732 if_clone_detach(&gre_cloner); 733 734 while (!LIST_EMPTY(&gre_softc_list)) 735 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 736 break; 737 } 738 return 0; 739} 740 741static moduledata_t gre_mod = { 742 "if_gre", 743 gremodevent, 744 0 745}; 746 747DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 748MODULE_VERSION(if_gre, 1); 749