if_gre.c revision 125024
1/* $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $ */ 2/* $FreeBSD: head/sys/net/if_gre.c 125024 2004-01-26 12:33:56Z 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 sc->wccp_ver = WCCP_V1; 182 if_attach(&sc->sc_if); 183 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 184 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 185 return (0); 186} 187 188static void 189gre_clone_destroy(ifp) 190 struct ifnet *ifp; 191{ 192 struct gre_softc *sc = ifp->if_softc; 193 194#ifdef INET 195 if (sc->encap != NULL) 196 encap_detach(sc->encap); 197#endif 198 LIST_REMOVE(sc, sc_list); 199 bpfdetach(ifp); 200 if_detach(ifp); 201 free(sc, M_GRE); 202} 203 204/* 205 * The output routine. Takes a packet and encapsulates it in the protocol 206 * given by sc->g_proto. See also RFC 1701 and RFC 2004 207 */ 208static int 209gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 210 struct rtentry *rt) 211{ 212 int error = 0; 213 struct gre_softc *sc = ifp->if_softc; 214 struct greip *gh; 215 struct ip *ip; 216 u_int16_t 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; 240 241 if (ifp->if_bpf) { 242 u_int32_t af = dst->sa_family; 243 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m); 244 } 245 246 m->m_flags &= ~(M_BCAST|M_MCAST); 247 248 if (sc->g_proto == IPPROTO_MOBILE) { 249 if (dst->sa_family == AF_INET) { 250 struct mbuf *m0; 251 int msiz; 252 253 ip = mtod(m, struct ip *); 254 255 /* 256 * RFC2004 specifies that fragmented diagrams shouldn't 257 * be encapsulated. 258 */ 259 if ((ip->ip_off & IP_MF) != 0) { 260 _IF_DROP(&ifp->if_snd); 261 m_freem(m); 262 error = EINVAL; /* is there better errno? */ 263 goto end; 264 } 265 memset(&mob_h, 0, MOB_H_SIZ_L); 266 mob_h.proto = (ip->ip_p) << 8; 267 mob_h.odst = ip->ip_dst.s_addr; 268 ip->ip_dst.s_addr = sc->g_dst.s_addr; 269 270 /* 271 * If the packet comes from our host, we only change 272 * the destination address in the IP header. 273 * Else we also need to save and change the source 274 */ 275 if (in_hosteq(ip->ip_src, sc->g_src)) { 276 msiz = MOB_H_SIZ_S; 277 } else { 278 mob_h.proto |= MOB_H_SBIT; 279 mob_h.osrc = ip->ip_src.s_addr; 280 ip->ip_src.s_addr = sc->g_src.s_addr; 281 msiz = MOB_H_SIZ_L; 282 } 283 mob_h.proto = htons(mob_h.proto); 284 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz); 285 286 if ((m->m_data - msiz) < m->m_pktdat) { 287 /* need new mbuf */ 288 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 289 if (m0 == NULL) { 290 _IF_DROP(&ifp->if_snd); 291 m_freem(m); 292 error = ENOBUFS; 293 goto end; 294 } 295 m0->m_next = m; 296 m->m_data += sizeof(struct ip); 297 m->m_len -= sizeof(struct ip); 298 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 299 m0->m_len = msiz + sizeof(struct ip); 300 m0->m_data += max_linkhdr; 301 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 302 sizeof(struct ip)); 303 m = m0; 304 } else { /* we have some space left in the old one */ 305 m->m_data -= msiz; 306 m->m_len += msiz; 307 m->m_pkthdr.len += msiz; 308 bcopy(ip, mtod(m, caddr_t), 309 sizeof(struct ip)); 310 } 311 ip = mtod(m, struct ip *); 312 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 313 ip->ip_len = ntohs(ip->ip_len) + msiz; 314 } else { /* AF_INET */ 315 _IF_DROP(&ifp->if_snd); 316 m_freem(m); 317 error = EINVAL; 318 goto end; 319 } 320 } else if (sc->g_proto == IPPROTO_GRE) { 321 switch (dst->sa_family) { 322 case AF_INET: 323 ip = mtod(m, struct ip *); 324 etype = ETHERTYPE_IP; 325 break; 326#ifdef NETATALK 327 case AF_APPLETALK: 328 etype = ETHERTYPE_ATALK; 329 break; 330#endif 331 default: 332 _IF_DROP(&ifp->if_snd); 333 m_freem(m); 334 error = EAFNOSUPPORT; 335 goto end; 336 } 337 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 338 } else { 339 _IF_DROP(&ifp->if_snd); 340 m_freem(m); 341 error = EINVAL; 342 goto end; 343 } 344 345 if (m == NULL) { /* impossible */ 346 _IF_DROP(&ifp->if_snd); 347 error = ENOBUFS; 348 goto end; 349 } 350 351 gh = mtod(m, struct greip *); 352 if (sc->g_proto == IPPROTO_GRE) { 353 /* we don't have any GRE flags for now */ 354 355 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 356 gh->gi_ptype = htons(etype); 357 } 358 359 gh->gi_pr = sc->g_proto; 360 if (sc->g_proto != IPPROTO_MOBILE) { 361 gh->gi_src = sc->g_src; 362 gh->gi_dst = sc->g_dst; 363 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 364 ((struct ip*)gh)->ip_ttl = GRE_TTL; 365 ((struct ip*)gh)->ip_tos = ip->ip_tos; 366 ((struct ip*)gh)->ip_id = ip->ip_id; 367 gh->gi_len = htons(m->m_pkthdr.len); 368 } 369 370 ifp->if_opackets++; 371 ifp->if_obytes += m->m_pkthdr.len; 372 /* send it off */ 373 error = ip_output(m, NULL, &sc->route, 0, 374 (struct ip_moptions *)NULL, (struct inpcb *)NULL); 375 end: 376 sc->called = 0; 377 if (error) 378 ifp->if_oerrors++; 379 return (error); 380} 381 382static int 383gre_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 if ((ifr->ifr_flags & IFF_LINK2) != 0) 412 sc->wccp_ver = WCCP_V2; 413 else 414 sc->wccp_ver = WCCP_V1; 415 goto recompute; 416 case SIOCSIFMTU: 417 if ((error = suser(curthread)) != 0) 418 break; 419 if (ifr->ifr_mtu < 576) { 420 error = EINVAL; 421 break; 422 } 423 ifp->if_mtu = ifr->ifr_mtu; 424 break; 425 case SIOCGIFMTU: 426 ifr->ifr_mtu = sc->sc_if.if_mtu; 427 break; 428 case SIOCADDMULTI: 429 case SIOCDELMULTI: 430 if ((error = suser(curthread)) != 0) 431 break; 432 if (ifr == 0) { 433 error = EAFNOSUPPORT; 434 break; 435 } 436 switch (ifr->ifr_addr.sa_family) { 437#ifdef INET 438 case AF_INET: 439 break; 440#endif 441 default: 442 error = EAFNOSUPPORT; 443 break; 444 } 445 break; 446 case GRESPROTO: 447 if ((error = suser(curthread)) != 0) 448 break; 449 sc->g_proto = ifr->ifr_flags; 450 switch (sc->g_proto) { 451 case IPPROTO_GRE: 452 ifp->if_flags |= IFF_LINK0; 453 break; 454 case IPPROTO_MOBILE: 455 ifp->if_flags &= ~IFF_LINK0; 456 break; 457 default: 458 error = EPROTONOSUPPORT; 459 break; 460 } 461 goto recompute; 462 case GREGPROTO: 463 ifr->ifr_flags = sc->g_proto; 464 break; 465 case GRESADDRS: 466 case GRESADDRD: 467 if ((error = suser(curthread)) != 0) 468 break; 469 /* 470 * set tunnel endpoints, compute a less specific route 471 * to the remote end and mark if as up 472 */ 473 sa = &ifr->ifr_addr; 474 if (cmd == GRESADDRS) 475 sc->g_src = (satosin(sa))->sin_addr; 476 if (cmd == GRESADDRD) 477 sc->g_dst = (satosin(sa))->sin_addr; 478 recompute: 479#ifdef INET 480 if (sc->encap != NULL) { 481 encap_detach(sc->encap); 482 sc->encap = NULL; 483 } 484#endif 485 if ((sc->g_src.s_addr != INADDR_ANY) && 486 (sc->g_dst.s_addr != INADDR_ANY)) { 487 bzero(&sp, sizeof(sp)); 488 bzero(&sm, sizeof(sm)); 489 bzero(&dp, sizeof(dp)); 490 bzero(&dm, sizeof(dm)); 491 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 492 sizeof(struct sockaddr_in); 493 sp.sin_family = sm.sin_family = dp.sin_family = 494 dm.sin_family = AF_INET; 495 sp.sin_addr = sc->g_src; 496 dp.sin_addr = sc->g_dst; 497 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 498 INADDR_BROADCAST; 499#ifdef INET 500 sc->encap = encap_attach(AF_INET, sc->g_proto, 501 sintosa(&sp), sintosa(&sm), sintosa(&dp), 502 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 503 &in_gre_protosw : &in_mobile_protosw, sc); 504 if (sc->encap == NULL) 505 printf("%s: unable to attach encap\n", 506 if_name(&sc->sc_if)); 507#endif 508 if (sc->route.ro_rt != 0) /* free old route */ 509 RTFREE(sc->route.ro_rt); 510 if (gre_compute_route(sc) == 0) 511 ifp->if_flags |= IFF_RUNNING; 512 else 513 ifp->if_flags &= ~IFF_RUNNING; 514 } 515 break; 516 case GREGADDRS: 517 memset(&si, 0, sizeof(si)); 518 si.sin_family = AF_INET; 519 si.sin_len = sizeof(struct sockaddr_in); 520 si.sin_addr.s_addr = sc->g_src.s_addr; 521 sa = sintosa(&si); 522 ifr->ifr_addr = *sa; 523 break; 524 case GREGADDRD: 525 memset(&si, 0, sizeof(si)); 526 si.sin_family = AF_INET; 527 si.sin_len = sizeof(struct sockaddr_in); 528 si.sin_addr.s_addr = sc->g_dst.s_addr; 529 sa = sintosa(&si); 530 ifr->ifr_addr = *sa; 531 break; 532 case SIOCSIFPHYADDR: 533 if ((error = suser(curthread)) != 0) 534 break; 535 if (aifr->ifra_addr.sin_family != AF_INET || 536 aifr->ifra_dstaddr.sin_family != AF_INET) { 537 error = EAFNOSUPPORT; 538 break; 539 } 540 if (aifr->ifra_addr.sin_len != sizeof(si) || 541 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 542 error = EINVAL; 543 break; 544 } 545 sc->g_src = aifr->ifra_addr.sin_addr; 546 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 547 goto recompute; 548 case SIOCSLIFPHYADDR: 549 if ((error = suser(curthread)) != 0) 550 break; 551 if (lifr->addr.ss_family != AF_INET || 552 lifr->dstaddr.ss_family != AF_INET) { 553 error = EAFNOSUPPORT; 554 break; 555 } 556 if (lifr->addr.ss_len != sizeof(si) || 557 lifr->dstaddr.ss_len != sizeof(si)) { 558 error = EINVAL; 559 break; 560 } 561 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 562 sc->g_dst = 563 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 564 goto recompute; 565 case SIOCDIFPHYADDR: 566 if ((error = suser(curthread)) != 0) 567 break; 568 sc->g_src.s_addr = INADDR_ANY; 569 sc->g_dst.s_addr = INADDR_ANY; 570 goto recompute; 571 case SIOCGLIFPHYADDR: 572 if (sc->g_src.s_addr == INADDR_ANY || 573 sc->g_dst.s_addr == INADDR_ANY) { 574 error = EADDRNOTAVAIL; 575 break; 576 } 577 memset(&si, 0, sizeof(si)); 578 si.sin_family = AF_INET; 579 si.sin_len = sizeof(struct sockaddr_in); 580 si.sin_addr.s_addr = sc->g_src.s_addr; 581 memcpy(&lifr->addr, &si, sizeof(si)); 582 si.sin_addr.s_addr = sc->g_dst.s_addr; 583 memcpy(&lifr->dstaddr, &si, sizeof(si)); 584 break; 585 case SIOCGIFPSRCADDR: 586#ifdef INET6 587 case SIOCGIFPSRCADDR_IN6: 588#endif 589 if (sc->g_src.s_addr == INADDR_ANY) { 590 error = EADDRNOTAVAIL; 591 break; 592 } 593 memset(&si, 0, sizeof(si)); 594 si.sin_family = AF_INET; 595 si.sin_len = sizeof(struct sockaddr_in); 596 si.sin_addr.s_addr = sc->g_src.s_addr; 597 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 598 break; 599 case SIOCGIFPDSTADDR: 600#ifdef INET6 601 case SIOCGIFPDSTADDR_IN6: 602#endif 603 if (sc->g_dst.s_addr == INADDR_ANY) { 604 error = EADDRNOTAVAIL; 605 break; 606 } 607 memset(&si, 0, sizeof(si)); 608 si.sin_family = AF_INET; 609 si.sin_len = sizeof(struct sockaddr_in); 610 si.sin_addr.s_addr = sc->g_dst.s_addr; 611 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 612 break; 613 default: 614 error = EINVAL; 615 break; 616 } 617 618 splx(s); 619 return (error); 620} 621 622/* 623 * computes a route to our destination that is not the one 624 * which would be taken by ip_output(), as this one will loop back to 625 * us. If the interface is p2p as a--->b, then a routing entry exists 626 * If we now send a packet to b (e.g. ping b), this will come down here 627 * gets src=a, dst=b tacked on and would from ip_output() sent back to 628 * if_gre. 629 * Goal here is to compute a route to b that is less specific than 630 * a-->b. We know that this one exists as in normal operation we have 631 * at least a default route which matches. 632 */ 633static int 634gre_compute_route(struct gre_softc *sc) 635{ 636 struct route *ro; 637 u_int32_t a, b, c; 638 639 ro = &sc->route; 640 641 memset(ro, 0, sizeof(struct route)); 642 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 643 ro->ro_dst.sa_family = AF_INET; 644 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 645 646 /* 647 * toggle last bit, so our interface is not found, but a less 648 * specific route. I'd rather like to specify a shorter mask, 649 * but this is not possible. Should work though. XXX 650 * there is a simpler way ... 651 */ 652 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 653 a = ntohl(sc->g_dst.s_addr); 654 b = a & 0x01; 655 c = a & 0xfffffffe; 656 b = b ^ 0x01; 657 a = b | c; 658 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 659 = htonl(a); 660 } 661 662#ifdef DIAGNOSTIC 663 printf("%s: searching for a route to %s", if_name(&sc->sc_if), 664 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 665#endif 666 667 rtalloc(ro); 668 669 /* 670 * check if this returned a route at all and this route is no 671 * recursion to ourself 672 */ 673 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 674#ifdef DIAGNOSTIC 675 if (ro->ro_rt == NULL) 676 printf(" - no route found!\n"); 677 else 678 printf(" - route loops back to ourself!\n"); 679#endif 680 return EADDRNOTAVAIL; 681 } 682 683 /* 684 * now change it back - else ip_output will just drop 685 * the route and search one to this interface ... 686 */ 687 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 688 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 689 690#ifdef DIAGNOSTIC 691 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 692 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 693 printf("\n"); 694#endif 695 696 return 0; 697} 698 699/* 700 * do a checksum of a buffer - much like in_cksum, which operates on 701 * mbufs. 702 */ 703u_int16_t 704gre_in_cksum(u_int16_t *p, u_int len) 705{ 706 u_int32_t sum = 0; 707 int nwords = len >> 1; 708 709 while (nwords-- != 0) 710 sum += *p++; 711 712 if (len & 1) { 713 union { 714 u_short w; 715 u_char c[2]; 716 } u; 717 u.c[0] = *(u_char *)p; 718 u.c[1] = 0; 719 sum += u.w; 720 } 721 722 /* end-around-carry */ 723 sum = (sum >> 16) + (sum & 0xffff); 724 sum += (sum >> 16); 725 return (~sum); 726} 727 728static int 729gremodevent(module_t mod, int type, void *data) 730{ 731 732 switch (type) { 733 case MOD_LOAD: 734 greattach(); 735 break; 736 case MOD_UNLOAD: 737 if_clone_detach(&gre_cloner); 738 739 while (!LIST_EMPTY(&gre_softc_list)) 740 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 741 break; 742 } 743 return 0; 744} 745 746static moduledata_t gre_mod = { 747 "if_gre", 748 gremodevent, 749 0 750}; 751 752DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 753MODULE_VERSION(if_gre, 1); 754