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 $ */
|
| 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);
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