1 /* $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 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 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 } 187 188 static void 189 gre_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 */ 208 static int 209 gre_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 memset((void *)gh, 0, sizeof(struct greip)); 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 = 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 } 380 381 static int 382 gre_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 if ((ifr->ifr_flags & IFF_LINK2) != 0) 411 sc->wccp_ver = WCCP_V2; 412 else 413 sc->wccp_ver = WCCP_V1; 414 goto recompute; 415 case SIOCSIFMTU: 416 if ((error = suser(curthread)) != 0) 417 break; 418 if (ifr->ifr_mtu < 576) { 419 error = EINVAL; 420 break; 421 } 422 ifp->if_mtu = ifr->ifr_mtu; 423 break; 424 case SIOCGIFMTU: 425 ifr->ifr_mtu = sc->sc_if.if_mtu; 426 break; 427 case SIOCADDMULTI: 428 case SIOCDELMULTI: 429 if ((error = suser(curthread)) != 0) 430 break; 431 if (ifr == 0) { 432 error = EAFNOSUPPORT; 433 break; 434 } 435 switch (ifr->ifr_addr.sa_family) { 436 #ifdef INET 437 case AF_INET: 438 break; 439 #endif 440 default: 441 error = EAFNOSUPPORT; 442 break; 443 } 444 break; 445 case GRESPROTO: 446 if ((error = suser(curthread)) != 0) 447 break; 448 sc->g_proto = ifr->ifr_flags; 449 switch (sc->g_proto) { 450 case IPPROTO_GRE: 451 ifp->if_flags |= IFF_LINK0; 452 break; 453 case IPPROTO_MOBILE: 454 ifp->if_flags &= ~IFF_LINK0; 455 break; 456 default: 457 error = EPROTONOSUPPORT; 458 break; 459 } 460 goto recompute; 461 case GREGPROTO: 462 ifr->ifr_flags = sc->g_proto; 463 break; 464 case GRESADDRS: 465 case GRESADDRD: 466 if ((error = suser(curthread)) != 0) 467 break; 468 /* 469 * set tunnel endpoints, compute a less specific route 470 * to the remote end and mark if as up 471 */ 472 sa = &ifr->ifr_addr; 473 if (cmd == GRESADDRS) 474 sc->g_src = (satosin(sa))->sin_addr; 475 if (cmd == GRESADDRD) 476 sc->g_dst = (satosin(sa))->sin_addr; 477 recompute: 478 #ifdef INET 479 if (sc->encap != NULL) { 480 encap_detach(sc->encap); 481 sc->encap = NULL; 482 } 483 #endif 484 if ((sc->g_src.s_addr != INADDR_ANY) && 485 (sc->g_dst.s_addr != INADDR_ANY)) { 486 bzero(&sp, sizeof(sp)); 487 bzero(&sm, sizeof(sm)); 488 bzero(&dp, sizeof(dp)); 489 bzero(&dm, sizeof(dm)); 490 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 491 sizeof(struct sockaddr_in); 492 sp.sin_family = sm.sin_family = dp.sin_family = 493 dm.sin_family = AF_INET; 494 sp.sin_addr = sc->g_src; 495 dp.sin_addr = sc->g_dst; 496 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 497 INADDR_BROADCAST; 498 #ifdef INET 499 sc->encap = encap_attach(AF_INET, sc->g_proto, 500 sintosa(&sp), sintosa(&sm), sintosa(&dp), 501 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 502 &in_gre_protosw : &in_mobile_protosw, sc); 503 if (sc->encap == NULL) 504 printf("%s: unable to attach encap\n", 505 if_name(&sc->sc_if)); 506 #endif 507 if (sc->route.ro_rt != 0) /* free old route */ 508 RTFREE(sc->route.ro_rt); 509 if (gre_compute_route(sc) == 0) 510 ifp->if_flags |= IFF_RUNNING; 511 else 512 ifp->if_flags &= ~IFF_RUNNING; 513 } 514 break; 515 case GREGADDRS: 516 memset(&si, 0, sizeof(si)); 517 si.sin_family = AF_INET; 518 si.sin_len = sizeof(struct sockaddr_in); 519 si.sin_addr.s_addr = sc->g_src.s_addr; 520 sa = sintosa(&si); 521 ifr->ifr_addr = *sa; 522 break; 523 case GREGADDRD: 524 memset(&si, 0, sizeof(si)); 525 si.sin_family = AF_INET; 526 si.sin_len = sizeof(struct sockaddr_in); 527 si.sin_addr.s_addr = sc->g_dst.s_addr; 528 sa = sintosa(&si); 529 ifr->ifr_addr = *sa; 530 break; 531 case SIOCSIFPHYADDR: 532 if ((error = suser(curthread)) != 0) 533 break; 534 if (aifr->ifra_addr.sin_family != AF_INET || 535 aifr->ifra_dstaddr.sin_family != AF_INET) { 536 error = EAFNOSUPPORT; 537 break; 538 } 539 if (aifr->ifra_addr.sin_len != sizeof(si) || 540 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 541 error = EINVAL; 542 break; 543 } 544 sc->g_src = aifr->ifra_addr.sin_addr; 545 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 546 goto recompute; 547 case SIOCSLIFPHYADDR: 548 if ((error = suser(curthread)) != 0) 549 break; 550 if (lifr->addr.ss_family != AF_INET || 551 lifr->dstaddr.ss_family != AF_INET) { 552 error = EAFNOSUPPORT; 553 break; 554 } 555 if (lifr->addr.ss_len != sizeof(si) || 556 lifr->dstaddr.ss_len != sizeof(si)) { 557 error = EINVAL; 558 break; 559 } 560 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 561 sc->g_dst = 562 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 563 goto recompute; 564 case SIOCDIFPHYADDR: 565 if ((error = suser(curthread)) != 0) 566 break; 567 sc->g_src.s_addr = INADDR_ANY; 568 sc->g_dst.s_addr = INADDR_ANY; 569 goto recompute; 570 case SIOCGLIFPHYADDR: 571 if (sc->g_src.s_addr == INADDR_ANY || 572 sc->g_dst.s_addr == INADDR_ANY) { 573 error = EADDRNOTAVAIL; 574 break; 575 } 576 memset(&si, 0, sizeof(si)); 577 si.sin_family = AF_INET; 578 si.sin_len = sizeof(struct sockaddr_in); 579 si.sin_addr.s_addr = sc->g_src.s_addr; 580 memcpy(&lifr->addr, &si, sizeof(si)); 581 si.sin_addr.s_addr = sc->g_dst.s_addr; 582 memcpy(&lifr->dstaddr, &si, sizeof(si)); 583 break; 584 case SIOCGIFPSRCADDR: 585 #ifdef INET6 586 case SIOCGIFPSRCADDR_IN6: 587 #endif 588 if (sc->g_src.s_addr == INADDR_ANY) { 589 error = EADDRNOTAVAIL; 590 break; 591 } 592 memset(&si, 0, sizeof(si)); 593 si.sin_family = AF_INET; 594 si.sin_len = sizeof(struct sockaddr_in); 595 si.sin_addr.s_addr = sc->g_src.s_addr; 596 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 597 break; 598 case SIOCGIFPDSTADDR: 599 #ifdef INET6 600 case SIOCGIFPDSTADDR_IN6: 601 #endif 602 if (sc->g_dst.s_addr == INADDR_ANY) { 603 error = EADDRNOTAVAIL; 604 break; 605 } 606 memset(&si, 0, sizeof(si)); 607 si.sin_family = AF_INET; 608 si.sin_len = sizeof(struct sockaddr_in); 609 si.sin_addr.s_addr = sc->g_dst.s_addr; 610 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 611 break; 612 default: 613 error = EINVAL; 614 break; 615 } 616 617 splx(s); 618 return (error); 619 } 620 621 /* 622 * computes a route to our destination that is not the one 623 * which would be taken by ip_output(), as this one will loop back to 624 * us. If the interface is p2p as a--->b, then a routing entry exists 625 * If we now send a packet to b (e.g. ping b), this will come down here 626 * gets src=a, dst=b tacked on and would from ip_output() sent back to 627 * if_gre. 628 * Goal here is to compute a route to b that is less specific than 629 * a-->b. We know that this one exists as in normal operation we have 630 * at least a default route which matches. 631 */ 632 static int 633 gre_compute_route(struct gre_softc *sc) 634 { 635 struct route *ro; 636 u_int32_t a, b, c; 637 638 ro = &sc->route; 639 640 memset(ro, 0, sizeof(struct route)); 641 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 642 ro->ro_dst.sa_family = AF_INET; 643 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 644 645 /* 646 * toggle last bit, so our interface is not found, but a less 647 * specific route. I'd rather like to specify a shorter mask, 648 * but this is not possible. Should work though. XXX 649 * there is a simpler way ... 650 */ 651 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 652 a = ntohl(sc->g_dst.s_addr); 653 b = a & 0x01; 654 c = a & 0xfffffffe; 655 b = b ^ 0x01; 656 a = b | c; 657 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 658 = htonl(a); 659 } 660 661 #ifdef DIAGNOSTIC 662 printf("%s: searching for a route to %s", if_name(&sc->sc_if), 663 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 664 #endif 665 666 rtalloc(ro); 667 668 /* 669 * check if this returned a route at all and this route is no 670 * recursion to ourself 671 */ 672 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 673 #ifdef DIAGNOSTIC 674 if (ro->ro_rt == NULL) 675 printf(" - no route found!\n"); 676 else 677 printf(" - route loops back to ourself!\n"); 678 #endif 679 return EADDRNOTAVAIL; 680 } 681 682 /* 683 * now change it back - else ip_output will just drop 684 * the route and search one to this interface ... 685 */ 686 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 687 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 688 689 #ifdef DIAGNOSTIC 690 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 691 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 692 printf("\n"); 693 #endif 694 695 return 0; 696 } 697 698 /* 699 * do a checksum of a buffer - much like in_cksum, which operates on 700 * mbufs. 701 */ 702 u_int16_t 703 gre_in_cksum(u_int16_t *p, u_int len) 704 { 705 u_int32_t sum = 0; 706 int nwords = len >> 1; 707 708 while (nwords-- != 0) 709 sum += *p++; 710 711 if (len & 1) { 712 union { 713 u_short w; 714 u_char c[2]; 715 } u; 716 u.c[0] = *(u_char *)p; 717 u.c[1] = 0; 718 sum += u.w; 719 } 720 721 /* end-around-carry */ 722 sum = (sum >> 16) + (sum & 0xffff); 723 sum += (sum >> 16); 724 return (~sum); 725 } 726 727 static int 728 gremodevent(module_t mod, int type, void *data) 729 { 730 731 switch (type) { 732 case MOD_LOAD: 733 greattach(); 734 break; 735 case MOD_UNLOAD: 736 if_clone_detach(&gre_cloner); 737 738 while (!LIST_EMPTY(&gre_softc_list)) 739 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 740 break; 741 } 742 return 0; 743 } 744 745 static moduledata_t gre_mod = { 746 "if_gre", 747 gremodevent, 748 0 749 }; 750 751 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 752 MODULE_VERSION(if_gre, 1); 753