Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/net/if_gre.c
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1 /* $NetBSD: if_gre.c,v 1.42 2002/08/14 00:23:27 itojun Exp $ */ 2 /* $FreeBSD: releng/5.2/sys/net/if_gre.c 122699 2003-11-14 20:58:00Z bms $ */ 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_OTHER, 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_OTHER; 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 /* see comment of other if_foo.c files */ 244 struct mbuf m0; 245 u_int32_t af = dst->sa_family; 246 247 m0.m_next = m; 248 m0.m_len = 4; 249 m0.m_data = (char *)⁡ 250 251 BPF_MTAP(ifp, &m0); 252 } 253 254 m->m_flags &= ~(M_BCAST|M_MCAST); 255 256 if (sc->g_proto == IPPROTO_MOBILE) { 257 if (dst->sa_family == AF_INET) { 258 struct mbuf *m0; 259 int msiz; 260 261 ip = mtod(m, struct ip *); 262 263 /* 264 * RFC2004 specifies that fragmented diagrams shouldn't 265 * be encapsulated. 266 */ 267 if ((ip->ip_off & IP_MF) != 0) { 268 _IF_DROP(&ifp->if_snd); 269 m_freem(m); 270 error = EINVAL; /* is there better errno? */ 271 goto end; 272 } 273 memset(&mob_h, 0, MOB_H_SIZ_L); 274 mob_h.proto = (ip->ip_p) << 8; 275 mob_h.odst = ip->ip_dst.s_addr; 276 ip->ip_dst.s_addr = sc->g_dst.s_addr; 277 278 /* 279 * If the packet comes from our host, we only change 280 * the destination address in the IP header. 281 * Else we also need to save and change the source 282 */ 283 if (in_hosteq(ip->ip_src, sc->g_src)) { 284 msiz = MOB_H_SIZ_S; 285 } else { 286 mob_h.proto |= MOB_H_SBIT; 287 mob_h.osrc = ip->ip_src.s_addr; 288 ip->ip_src.s_addr = sc->g_src.s_addr; 289 msiz = MOB_H_SIZ_L; 290 } 291 mob_h.proto = htons(mob_h.proto); 292 mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz); 293 294 if ((m->m_data - msiz) < m->m_pktdat) { 295 /* need new mbuf */ 296 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 297 if (m0 == NULL) { 298 _IF_DROP(&ifp->if_snd); 299 m_freem(m); 300 error = ENOBUFS; 301 goto end; 302 } 303 m0->m_next = m; 304 m->m_data += sizeof(struct ip); 305 m->m_len -= sizeof(struct ip); 306 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 307 m0->m_len = msiz + sizeof(struct ip); 308 m0->m_data += max_linkhdr; 309 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 310 sizeof(struct ip)); 311 m = m0; 312 } else { /* we have some space left in the old one */ 313 m->m_data -= msiz; 314 m->m_len += msiz; 315 m->m_pkthdr.len += msiz; 316 bcopy(ip, mtod(m, caddr_t), 317 sizeof(struct ip)); 318 } 319 ip = mtod(m, struct ip *); 320 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 321 ip->ip_len = ntohs(ip->ip_len) + msiz; 322 } else { /* AF_INET */ 323 _IF_DROP(&ifp->if_snd); 324 m_freem(m); 325 error = EINVAL; 326 goto end; 327 } 328 } else if (sc->g_proto == IPPROTO_GRE) { 329 switch (dst->sa_family) { 330 case AF_INET: 331 ip = mtod(m, struct ip *); 332 etype = ETHERTYPE_IP; 333 break; 334 #ifdef NETATALK 335 case AF_APPLETALK: 336 etype = ETHERTYPE_ATALK; 337 break; 338 #endif 339 default: 340 _IF_DROP(&ifp->if_snd); 341 m_freem(m); 342 error = EAFNOSUPPORT; 343 goto end; 344 } 345 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 346 } else { 347 _IF_DROP(&ifp->if_snd); 348 m_freem(m); 349 error = EINVAL; 350 goto end; 351 } 352 353 if (m == NULL) { /* impossible */ 354 _IF_DROP(&ifp->if_snd); 355 error = ENOBUFS; 356 goto end; 357 } 358 359 gh = mtod(m, struct greip *); 360 if (sc->g_proto == IPPROTO_GRE) { 361 /* we don't have any GRE flags for now */ 362 363 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 364 gh->gi_ptype = htons(etype); 365 } 366 367 gh->gi_pr = sc->g_proto; 368 if (sc->g_proto != IPPROTO_MOBILE) { 369 gh->gi_src = sc->g_src; 370 gh->gi_dst = sc->g_dst; 371 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 372 ((struct ip*)gh)->ip_ttl = GRE_TTL; 373 ((struct ip*)gh)->ip_tos = ip->ip_tos; 374 ((struct ip*)gh)->ip_id = ip->ip_id; 375 gh->gi_len = m->m_pkthdr.len; 376 } 377 378 ifp->if_opackets++; 379 ifp->if_obytes += m->m_pkthdr.len; 380 /* send it off */ 381 error = ip_output(m, NULL, &sc->route, 0, NULL, NULL); 382 end: 383 sc->called = 0; 384 if (error) 385 ifp->if_oerrors++; 386 return (error); 387 } 388 389 static int 390 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 391 { 392 struct ifreq *ifr = (struct ifreq *)data; 393 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 394 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 395 struct gre_softc *sc = ifp->if_softc; 396 int s; 397 struct sockaddr_in si; 398 struct sockaddr *sa = NULL; 399 int error; 400 struct sockaddr_in sp, sm, dp, dm; 401 402 error = 0; 403 404 s = splnet(); 405 switch (cmd) { 406 case SIOCSIFADDR: 407 ifp->if_flags |= IFF_UP; 408 break; 409 case SIOCSIFDSTADDR: 410 break; 411 case SIOCSIFFLAGS: 412 if ((error = suser(curthread)) != 0) 413 break; 414 if ((ifr->ifr_flags & IFF_LINK0) != 0) 415 sc->g_proto = IPPROTO_GRE; 416 else 417 sc->g_proto = IPPROTO_MOBILE; 418 goto recompute; 419 case SIOCSIFMTU: 420 if ((error = suser(curthread)) != 0) 421 break; 422 if (ifr->ifr_mtu < 576) { 423 error = EINVAL; 424 break; 425 } 426 ifp->if_mtu = ifr->ifr_mtu; 427 break; 428 case SIOCGIFMTU: 429 ifr->ifr_mtu = sc->sc_if.if_mtu; 430 break; 431 case SIOCADDMULTI: 432 case SIOCDELMULTI: 433 if ((error = suser(curthread)) != 0) 434 break; 435 if (ifr == 0) { 436 error = EAFNOSUPPORT; 437 break; 438 } 439 switch (ifr->ifr_addr.sa_family) { 440 #ifdef INET 441 case AF_INET: 442 break; 443 #endif 444 default: 445 error = EAFNOSUPPORT; 446 break; 447 } 448 break; 449 case GRESPROTO: 450 if ((error = suser(curthread)) != 0) 451 break; 452 sc->g_proto = ifr->ifr_flags; 453 switch (sc->g_proto) { 454 case IPPROTO_GRE: 455 ifp->if_flags |= IFF_LINK0; 456 break; 457 case IPPROTO_MOBILE: 458 ifp->if_flags &= ~IFF_LINK0; 459 break; 460 default: 461 error = EPROTONOSUPPORT; 462 break; 463 } 464 goto recompute; 465 case GREGPROTO: 466 ifr->ifr_flags = sc->g_proto; 467 break; 468 case GRESADDRS: 469 case GRESADDRD: 470 if ((error = suser(curthread)) != 0) 471 break; 472 /* 473 * set tunnel endpoints, compute a less specific route 474 * to the remote end and mark if as up 475 */ 476 sa = &ifr->ifr_addr; 477 if (cmd == GRESADDRS) 478 sc->g_src = (satosin(sa))->sin_addr; 479 if (cmd == GRESADDRD) 480 sc->g_dst = (satosin(sa))->sin_addr; 481 recompute: 482 #ifdef INET 483 if (sc->encap != NULL) { 484 encap_detach(sc->encap); 485 sc->encap = NULL; 486 } 487 #endif 488 if ((sc->g_src.s_addr != INADDR_ANY) && 489 (sc->g_dst.s_addr != INADDR_ANY)) { 490 bzero(&sp, sizeof(sp)); 491 bzero(&sm, sizeof(sm)); 492 bzero(&dp, sizeof(dp)); 493 bzero(&dm, sizeof(dm)); 494 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 495 sizeof(struct sockaddr_in); 496 sp.sin_family = sm.sin_family = dp.sin_family = 497 dm.sin_family = AF_INET; 498 sp.sin_addr = sc->g_src; 499 dp.sin_addr = sc->g_dst; 500 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 501 INADDR_BROADCAST; 502 #ifdef INET 503 sc->encap = encap_attach(AF_INET, sc->g_proto, 504 sintosa(&sp), sintosa(&sm), sintosa(&dp), 505 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 506 &in_gre_protosw : &in_mobile_protosw, sc); 507 if (sc->encap == NULL) 508 printf("%s: unable to attach encap\n", 509 if_name(&sc->sc_if)); 510 #endif 511 if (sc->route.ro_rt != 0) /* free old route */ 512 RTFREE(sc->route.ro_rt); 513 if (gre_compute_route(sc) == 0) 514 ifp->if_flags |= IFF_RUNNING; 515 else 516 ifp->if_flags &= ~IFF_RUNNING; 517 } 518 break; 519 case GREGADDRS: 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_src.s_addr; 524 sa = sintosa(&si); 525 ifr->ifr_addr = *sa; 526 break; 527 case GREGADDRD: 528 memset(&si, 0, sizeof(si)); 529 si.sin_family = AF_INET; 530 si.sin_len = sizeof(struct sockaddr_in); 531 si.sin_addr.s_addr = sc->g_dst.s_addr; 532 sa = sintosa(&si); 533 ifr->ifr_addr = *sa; 534 break; 535 case SIOCSIFPHYADDR: 536 if ((error = suser(curthread)) != 0) 537 break; 538 if (aifr->ifra_addr.sin_family != AF_INET || 539 aifr->ifra_dstaddr.sin_family != AF_INET) { 540 error = EAFNOSUPPORT; 541 break; 542 } 543 if (aifr->ifra_addr.sin_len != sizeof(si) || 544 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 545 error = EINVAL; 546 break; 547 } 548 sc->g_src = aifr->ifra_addr.sin_addr; 549 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 550 goto recompute; 551 case SIOCSLIFPHYADDR: 552 if ((error = suser(curthread)) != 0) 553 break; 554 if (lifr->addr.ss_family != AF_INET || 555 lifr->dstaddr.ss_family != AF_INET) { 556 error = EAFNOSUPPORT; 557 break; 558 } 559 if (lifr->addr.ss_len != sizeof(si) || 560 lifr->dstaddr.ss_len != sizeof(si)) { 561 error = EINVAL; 562 break; 563 } 564 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 565 sc->g_dst = 566 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 567 goto recompute; 568 case SIOCDIFPHYADDR: 569 if ((error = suser(curthread)) != 0) 570 break; 571 sc->g_src.s_addr = INADDR_ANY; 572 sc->g_dst.s_addr = INADDR_ANY; 573 goto recompute; 574 case SIOCGLIFPHYADDR: 575 if (sc->g_src.s_addr == INADDR_ANY || 576 sc->g_dst.s_addr == INADDR_ANY) { 577 error = EADDRNOTAVAIL; 578 break; 579 } 580 memset(&si, 0, sizeof(si)); 581 si.sin_family = AF_INET; 582 si.sin_len = sizeof(struct sockaddr_in); 583 si.sin_addr.s_addr = sc->g_src.s_addr; 584 memcpy(&lifr->addr, &si, sizeof(si)); 585 si.sin_addr.s_addr = sc->g_dst.s_addr; 586 memcpy(&lifr->dstaddr, &si, sizeof(si)); 587 break; 588 case SIOCGIFPSRCADDR: 589 #ifdef INET6 590 case SIOCGIFPSRCADDR_IN6: 591 #endif 592 if (sc->g_src.s_addr == INADDR_ANY) { 593 error = EADDRNOTAVAIL; 594 break; 595 } 596 memset(&si, 0, sizeof(si)); 597 si.sin_family = AF_INET; 598 si.sin_len = sizeof(struct sockaddr_in); 599 si.sin_addr.s_addr = sc->g_src.s_addr; 600 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 601 break; 602 case SIOCGIFPDSTADDR: 603 #ifdef INET6 604 case SIOCGIFPDSTADDR_IN6: 605 #endif 606 if (sc->g_dst.s_addr == INADDR_ANY) { 607 error = EADDRNOTAVAIL; 608 break; 609 } 610 memset(&si, 0, sizeof(si)); 611 si.sin_family = AF_INET; 612 si.sin_len = sizeof(struct sockaddr_in); 613 si.sin_addr.s_addr = sc->g_dst.s_addr; 614 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 615 break; 616 default: 617 error = EINVAL; 618 break; 619 } 620 621 splx(s); 622 return (error); 623 } 624 625 /* 626 * computes a route to our destination that is not the one 627 * which would be taken by ip_output(), as this one will loop back to 628 * us. If the interface is p2p as a--->b, then a routing entry exists 629 * If we now send a packet to b (e.g. ping b), this will come down here 630 * gets src=a, dst=b tacked on and would from ip_ouput() sent back to 631 * if_gre. 632 * Goal here is to compute a route to b that is less specific than 633 * a-->b. We know that this one exists as in normal operation we have 634 * at least a default route which matches. 635 */ 636 static int 637 gre_compute_route(struct gre_softc *sc) 638 { 639 struct route *ro; 640 u_int32_t a, b, c; 641 642 ro = &sc->route; 643 644 memset(ro, 0, sizeof(struct route)); 645 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 646 ro->ro_dst.sa_family = AF_INET; 647 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 648 649 /* 650 * toggle last bit, so our interface is not found, but a less 651 * specific route. I'd rather like to specify a shorter mask, 652 * but this is not possible. Should work though. XXX 653 * there is a simpler way ... 654 */ 655 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 656 a = ntohl(sc->g_dst.s_addr); 657 b = a & 0x01; 658 c = a & 0xfffffffe; 659 b = b ^ 0x01; 660 a = b | c; 661 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 662 = htonl(a); 663 } 664 665 #ifdef DIAGNOSTIC 666 printf("%s: searching a route to %s", if_name(&sc->sc_if), 667 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 668 #endif 669 670 rtalloc(ro); 671 672 /* 673 * check if this returned a route at all and this route is no 674 * recursion to ourself 675 */ 676 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 677 #ifdef DIAGNOSTIC 678 if (ro->ro_rt == NULL) 679 printf(" - no route found!\n"); 680 else 681 printf(" - route loops back to ourself!\n"); 682 #endif 683 return EADDRNOTAVAIL; 684 } 685 686 /* 687 * now change it back - else ip_output will just drop 688 * the route and search one to this interface ... 689 */ 690 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 691 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 692 693 #ifdef DIAGNOSTIC 694 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 695 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 696 printf("\n"); 697 #endif 698 699 return 0; 700 } 701 702 /* 703 * do a checksum of a buffer - much like in_cksum, which operates on 704 * mbufs. 705 */ 706 u_short 707 gre_in_cksum(u_short *p, u_int len) 708 { 709 u_int sum = 0; 710 int nwords = len >> 1; 711 712 while (nwords-- != 0) 713 sum += *p++; 714 715 if (len & 1) { 716 union { 717 u_short w; 718 u_char c[2]; 719 } u; 720 u.c[0] = *(u_char *)p; 721 u.c[1] = 0; 722 sum += u.w; 723 } 724 725 /* end-around-carry */ 726 sum = (sum >> 16) + (sum & 0xffff); 727 sum += (sum >> 16); 728 return (~sum); 729 } 730 731 static int 732 gremodevent(module_t mod, int type, void *data) 733 { 734 735 switch (type) { 736 case MOD_LOAD: 737 greattach(); 738 break; 739 case MOD_UNLOAD: 740 if_clone_detach(&gre_cloner); 741 742 while (!LIST_EMPTY(&gre_softc_list)) 743 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 744 break; 745 } 746 return 0; 747 } 748 749 static moduledata_t gre_mod = { 750 "if_gre", 751 gremodevent, 752 0 753 }; 754 755 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 756 MODULE_VERSION(if_gre, 1);
Cache object: f285a5c0336c80c66bef8cf9415a609c
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