1 /* $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $ */
5 * Copyright (c) 1998 The NetBSD Foundation, Inc.
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Heiko W.Rupp <hwr@pilhuhn.de>
11 * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the NetBSD
24 * Foundation, Inc. and its contributors.
25 * 4. Neither the name of The NetBSD Foundation nor the names of its
26 * contributors may be used to endorse or promote products derived
27 * from this software without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
30 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
31 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
32 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
33 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
34 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
35 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
36 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
37 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
39 * POSSIBILITY OF SUCH DAMAGE.
43 * Encapsulate L3 protocols into IP
44 * See RFC 2784 (successor of RFC 1701 and 1702) for more details.
45 * If_gre is compatible with Cisco GRE tunnels, so you can
46 * have a NetBSD box as the other end of a tunnel interface of a Cisco
47 * router. See gre(4) for more details.
48 * Also supported: IP in IP encaps (proto 55) as of RFC 2004
51 #include "opt_atalk.h"
53 #include "opt_inet6.h"
55 #include <sys/param.h>
57 #include <sys/kernel.h>
58 #include <sys/libkern.h>
59 #include <sys/malloc.h>
60 #include <sys/module.h>
64 #include <sys/protosw.h>
65 #include <sys/socket.h>
66 #include <sys/sockio.h>
67 #include <sys/sysctl.h>
68 #include <sys/systm.h>
70 #include <net/ethernet.h>
72 #include <net/if_clone.h>
73 #include <net/if_types.h>
74 #include <net/route.h>
78 #include <netinet/in.h>
79 #include <netinet/in_systm.h>
80 #include <netinet/in_var.h>
81 #include <netinet/ip.h>
82 #include <netinet/ip_gre.h>
83 #include <netinet/ip_var.h>
84 #include <netinet/ip_encap.h>
86 #error "Huh? if_gre without inet?"
91 #include <net/if_gre.h>
94 * It is not easy to calculate the right value for a GRE MTU.
95 * We leave this task to the admin and use the same default that
100 #define GRENAME "gre"
102 #define MTAG_COOKIE_GRE 1307983903
103 #define MTAG_GRE_NESTING 1
104 struct mtag_gre_nesting {
111 * gre_mtx protects all global variables in if_gre.c.
112 * XXX: gre_softc data not protected yet.
115 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
117 struct gre_softc_head gre_softc_list;
119 static int gre_clone_create(struct if_clone *, int, caddr_t);
120 static void gre_clone_destroy(struct ifnet *);
121 static int gre_ioctl(struct ifnet *, u_long, caddr_t);
122 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
125 IFC_SIMPLE_DECLARE(gre, 0);
127 static int gre_compute_route(struct gre_softc *sc);
129 static void greattach(void);
132 extern struct domain inetdomain;
133 static const struct protosw in_gre_protosw = {
135 .pr_domain = &inetdomain,
136 .pr_protocol = IPPROTO_GRE,
137 .pr_flags = PR_ATOMIC|PR_ADDR,
138 .pr_input = gre_input,
139 .pr_output = (pr_output_t *)rip_output,
140 .pr_ctlinput = rip_ctlinput,
141 .pr_ctloutput = rip_ctloutput,
142 .pr_usrreqs = &rip_usrreqs
144 static const struct protosw in_mobile_protosw = {
146 .pr_domain = &inetdomain,
147 .pr_protocol = IPPROTO_MOBILE,
148 .pr_flags = PR_ATOMIC|PR_ADDR,
149 .pr_input = gre_mobile_input,
150 .pr_output = (pr_output_t *)rip_output,
151 .pr_ctlinput = rip_ctlinput,
152 .pr_ctloutput = rip_ctloutput,
153 .pr_usrreqs = &rip_usrreqs
157 SYSCTL_DECL(_net_link);
158 SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
159 "Generic Routing Encapsulation");
162 * This macro controls the default upper limitation on nesting of gre tunnels.
163 * Since, setting a large value to this macro with a careless configuration
164 * may introduce system crash, we don't allow any nestings by default.
165 * If you need to configure nested gre tunnels, you can define this macro
166 * in your kernel configuration file. However, if you do so, please be
167 * careful to configure the tunnels so that it won't make a loop.
169 #define MAX_GRE_NEST 1
171 static int max_gre_nesting = MAX_GRE_NEST;
172 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
173 &max_gre_nesting, 0, "Max nested tunnels");
180 mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
181 LIST_INIT(&gre_softc_list);
182 if_clone_attach(&gre_cloner);
186 gre_clone_create(ifc, unit, params)
187 struct if_clone *ifc;
191 struct gre_softc *sc;
193 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
195 GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
196 if (GRE2IFP(sc) == NULL) {
201 GRE2IFP(sc)->if_softc = sc;
202 if_initname(GRE2IFP(sc), ifc->ifc_name, unit);
204 GRE2IFP(sc)->if_snd.ifq_maxlen = ifqmaxlen;
205 GRE2IFP(sc)->if_addrlen = 0;
206 GRE2IFP(sc)->if_hdrlen = 24; /* IP + GRE */
207 GRE2IFP(sc)->if_mtu = GREMTU;
208 GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
209 GRE2IFP(sc)->if_output = gre_output;
210 GRE2IFP(sc)->if_ioctl = gre_ioctl;
211 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
212 sc->g_proto = IPPROTO_GRE;
213 GRE2IFP(sc)->if_flags |= IFF_LINK0;
215 sc->gre_fibnum = curthread->td_proc->p_fibnum;
216 sc->wccp_ver = WCCP_V1;
218 if_attach(GRE2IFP(sc));
219 bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
221 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
222 mtx_unlock(&gre_mtx);
227 gre_clone_destroy(ifp)
230 struct gre_softc *sc = ifp->if_softc;
233 LIST_REMOVE(sc, sc_list);
234 mtx_unlock(&gre_mtx);
237 if (sc->encap != NULL)
238 encap_detach(sc->encap);
247 * The output routine. Takes a packet and encapsulates it in the protocol
248 * given by sc->g_proto. See also RFC 1701 and RFC 2004
251 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
255 struct gre_softc *sc = ifp->if_softc;
259 struct mtag_gre_nesting *gt;
261 u_short gre_ip_id = 0;
262 uint8_t gre_ip_tos = 0;
264 struct mobile_h mob_h;
269 * gre may cause infinite recursion calls when misconfigured. High
270 * nesting level may cause stack exhaustion. We'll prevent this by
271 * detecting loops and by introducing upper limit.
273 mtag = m_tag_locate(m, MTAG_COOKIE_GRE, MTAG_GRE_NESTING, NULL);
277 gt = (struct mtag_gre_nesting *)(mtag + 1);
279 if (gt->count > min(gt->max,max_gre_nesting)) {
280 printf("%s: hit maximum recursion limit %u on %s\n",
281 __func__, gt->count - 1, ifp->if_xname);
283 error = EIO; /* is there better errno? */
288 for (max = gt->count - 1; max > 0; max--) {
294 printf("%s: detected loop with nexting %u on %s\n",
295 __func__, gt->count-1, ifp->if_xname);
297 error = EIO; /* is there better errno? */
304 * Given that people should NOT increase max_gre_nesting beyond
305 * their real needs, we allocate once per packet rather than
306 * allocating an mtag once per passing through gre.
308 * Note: the sysctl does not actually check for saneness, so we
309 * limit the maximum numbers of possible recursions here.
311 max = imin(max_gre_nesting, 256);
312 /* If someone sets the sysctl <= 0, we want at least 1. */
314 len = sizeof(struct mtag_gre_nesting) +
315 max * sizeof(struct ifnet *);
316 mtag = m_tag_alloc(MTAG_COOKIE_GRE, MTAG_GRE_NESTING, len,
323 gt = (struct mtag_gre_nesting *)(mtag + 1);
328 m_tag_prepend(m, mtag);
331 if (!((ifp->if_flags & IFF_UP) &&
332 (ifp->if_drv_flags & IFF_DRV_RUNNING)) ||
333 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
342 /* BPF writes need to be handled specially. */
343 if (dst->sa_family == AF_UNSPEC) {
344 bcopy(dst->sa_data, &af, sizeof(af));
348 if (bpf_peers_present(ifp->if_bpf)) {
350 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
353 m->m_flags &= ~(M_BCAST|M_MCAST);
355 if (sc->g_proto == IPPROTO_MOBILE) {
356 if (dst->sa_family == AF_INET) {
360 ip = mtod(m, struct ip *);
363 * RFC2004 specifies that fragmented diagrams shouldn't
366 if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
367 _IF_DROP(&ifp->if_snd);
369 error = EINVAL; /* is there better errno? */
372 memset(&mob_h, 0, MOB_H_SIZ_L);
373 mob_h.proto = (ip->ip_p) << 8;
374 mob_h.odst = ip->ip_dst.s_addr;
375 ip->ip_dst.s_addr = sc->g_dst.s_addr;
378 * If the packet comes from our host, we only change
379 * the destination address in the IP header.
380 * Else we also need to save and change the source
382 if (in_hosteq(ip->ip_src, sc->g_src)) {
385 mob_h.proto |= MOB_H_SBIT;
386 mob_h.osrc = ip->ip_src.s_addr;
387 ip->ip_src.s_addr = sc->g_src.s_addr;
390 mob_h.proto = htons(mob_h.proto);
391 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz);
393 if ((m->m_data - msiz) < m->m_pktdat) {
395 MGETHDR(m0, M_DONTWAIT, MT_DATA);
397 _IF_DROP(&ifp->if_snd);
403 m->m_data += sizeof(struct ip);
404 m->m_len -= sizeof(struct ip);
405 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
406 m0->m_len = msiz + sizeof(struct ip);
407 m0->m_data += max_linkhdr;
408 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
411 } else { /* we have some space left in the old one */
414 m->m_pkthdr.len += msiz;
415 bcopy(ip, mtod(m, caddr_t),
418 ip = mtod(m, struct ip *);
419 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
420 ip->ip_len = ntohs(ip->ip_len) + msiz;
421 } else { /* AF_INET */
422 _IF_DROP(&ifp->if_snd);
427 } else if (sc->g_proto == IPPROTO_GRE) {
428 switch (dst->sa_family) {
430 ip = mtod(m, struct ip *);
431 gre_ip_tos = ip->ip_tos;
432 gre_ip_id = ip->ip_id;
433 if (sc->wccp_ver == WCCP_V2) {
434 extra = sizeof(uint32_t);
435 etype = WCCP_PROTOCOL_TYPE;
437 etype = ETHERTYPE_IP;
442 gre_ip_id = ip_newid();
443 etype = ETHERTYPE_IPV6;
448 etype = ETHERTYPE_ATALK;
452 _IF_DROP(&ifp->if_snd);
454 error = EAFNOSUPPORT;
458 /* Reserve space for GRE header + optional GRE key */
459 int hdrlen = sizeof(struct greip) + extra;
461 hdrlen += sizeof(uint32_t);
462 M_PREPEND(m, hdrlen, M_DONTWAIT);
464 _IF_DROP(&ifp->if_snd);
470 if (m == NULL) { /* mbuf allocation failed */
471 _IF_DROP(&ifp->if_snd);
476 M_SETFIB(m, sc->gre_fibnum); /* The envelope may use a different FIB */
478 gh = mtod(m, struct greip *);
479 if (sc->g_proto == IPPROTO_GRE) {
480 uint32_t *options = gh->gi_options;
482 memset((void *)gh, 0, sizeof(struct greip) + extra);
483 gh->gi_ptype = htons(etype);
489 gh->gi_flags |= htons(GRE_KP);
490 *(options++) = htonl(sc->key);
494 gh->gi_pr = sc->g_proto;
495 if (sc->g_proto != IPPROTO_MOBILE) {
496 gh->gi_src = sc->g_src;
497 gh->gi_dst = sc->g_dst;
498 ((struct ip*)gh)->ip_v = IPPROTO_IPV4;
499 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
500 ((struct ip*)gh)->ip_ttl = GRE_TTL;
501 ((struct ip*)gh)->ip_tos = gre_ip_tos;
502 ((struct ip*)gh)->ip_id = gre_ip_id;
503 gh->gi_len = m->m_pkthdr.len;
507 ifp->if_obytes += m->m_pkthdr.len;
509 * Send it off and with IP_FORWARD flag to prevent it from
510 * overwriting the ip_id again. ip_id is already set to the
511 * ip_id of the encapsulated packet.
513 error = ip_output(m, NULL, &sc->route, IP_FORWARDING,
514 (struct ip_moptions *)NULL, (struct inpcb *)NULL);
522 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
524 struct ifreq *ifr = (struct ifreq *)data;
525 struct if_laddrreq *lifr = (struct if_laddrreq *)data;
526 struct in_aliasreq *aifr = (struct in_aliasreq *)data;
527 struct gre_softc *sc = ifp->if_softc;
529 struct sockaddr_in si;
530 struct sockaddr *sa = NULL;
532 struct sockaddr_in sp, sm, dp, dm;
541 ifp->if_flags |= IFF_UP;
547 * XXXRW: Isn't this priv_check() redundant to the ifnet
550 if ((error = priv_check(curthread, PRIV_NET_SETIFFLAGS)) != 0)
552 if ((ifr->ifr_flags & IFF_LINK0) != 0)
553 sc->g_proto = IPPROTO_GRE;
555 sc->g_proto = IPPROTO_MOBILE;
556 if ((ifr->ifr_flags & IFF_LINK2) != 0)
557 sc->wccp_ver = WCCP_V2;
559 sc->wccp_ver = WCCP_V1;
563 * XXXRW: Isn't this priv_check() redundant to the ifnet
566 if ((error = priv_check(curthread, PRIV_NET_SETIFMTU)) != 0)
568 if (ifr->ifr_mtu < 576) {
572 ifp->if_mtu = ifr->ifr_mtu;
575 ifr->ifr_mtu = GRE2IFP(sc)->if_mtu;
579 * XXXRW: Isn't this priv_checkr() redundant to the ifnet
582 if ((error = priv_check(curthread, PRIV_NET_ADDMULTI)) != 0)
585 error = EAFNOSUPPORT;
588 switch (ifr->ifr_addr.sa_family) {
598 error = EAFNOSUPPORT;
604 * XXXRW: Isn't this priv_check() redundant to the ifnet
607 if ((error = priv_check(curthread, PRIV_NET_DELIFGROUP)) != 0)
610 error = EAFNOSUPPORT;
613 switch (ifr->ifr_addr.sa_family) {
623 error = EAFNOSUPPORT;
629 * XXXRW: Isn't this priv_check() redundant to the ifnet
632 if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
634 sc->g_proto = ifr->ifr_flags;
635 switch (sc->g_proto) {
637 ifp->if_flags |= IFF_LINK0;
640 ifp->if_flags &= ~IFF_LINK0;
643 error = EPROTONOSUPPORT;
648 ifr->ifr_flags = sc->g_proto;
652 error = priv_check(curthread, PRIV_NET_GRE);
656 * set tunnel endpoints, compute a less specific route
657 * to the remote end and mark if as up
660 if (cmd == GRESADDRS)
661 sc->g_src = (satosin(sa))->sin_addr;
662 if (cmd == GRESADDRD)
663 sc->g_dst = (satosin(sa))->sin_addr;
666 if (sc->encap != NULL) {
667 encap_detach(sc->encap);
671 if ((sc->g_src.s_addr != INADDR_ANY) &&
672 (sc->g_dst.s_addr != INADDR_ANY)) {
673 bzero(&sp, sizeof(sp));
674 bzero(&sm, sizeof(sm));
675 bzero(&dp, sizeof(dp));
676 bzero(&dm, sizeof(dm));
677 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
678 sizeof(struct sockaddr_in);
679 sp.sin_family = sm.sin_family = dp.sin_family =
680 dm.sin_family = AF_INET;
681 sp.sin_addr = sc->g_src;
682 dp.sin_addr = sc->g_dst;
683 sm.sin_addr.s_addr = dm.sin_addr.s_addr =
686 sc->encap = encap_attach(AF_INET, sc->g_proto,
687 sintosa(&sp), sintosa(&sm), sintosa(&dp),
688 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
689 &in_gre_protosw : &in_mobile_protosw, sc);
690 if (sc->encap == NULL)
691 printf("%s: unable to attach encap\n",
692 if_name(GRE2IFP(sc)));
694 if (sc->route.ro_rt != 0) /* free old route */
695 RTFREE(sc->route.ro_rt);
696 if (gre_compute_route(sc) == 0)
697 ifp->if_drv_flags |= IFF_DRV_RUNNING;
699 ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
703 memset(&si, 0, sizeof(si));
704 si.sin_family = AF_INET;
705 si.sin_len = sizeof(struct sockaddr_in);
706 si.sin_addr.s_addr = sc->g_src.s_addr;
708 error = prison_if(curthread->td_ucred, sa);
714 memset(&si, 0, sizeof(si));
715 si.sin_family = AF_INET;
716 si.sin_len = sizeof(struct sockaddr_in);
717 si.sin_addr.s_addr = sc->g_dst.s_addr;
719 error = prison_if(curthread->td_ucred, sa);
726 * XXXRW: Isn't this priv_check() redundant to the ifnet
729 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
731 if (aifr->ifra_addr.sin_family != AF_INET ||
732 aifr->ifra_dstaddr.sin_family != AF_INET) {
733 error = EAFNOSUPPORT;
736 if (aifr->ifra_addr.sin_len != sizeof(si) ||
737 aifr->ifra_dstaddr.sin_len != sizeof(si)) {
741 sc->g_src = aifr->ifra_addr.sin_addr;
742 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
744 case SIOCSLIFPHYADDR:
746 * XXXRW: Isn't this priv_check() redundant to the ifnet
749 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
751 if (lifr->addr.ss_family != AF_INET ||
752 lifr->dstaddr.ss_family != AF_INET) {
753 error = EAFNOSUPPORT;
756 if (lifr->addr.ss_len != sizeof(si) ||
757 lifr->dstaddr.ss_len != sizeof(si)) {
761 sc->g_src = (satosin(&lifr->addr))->sin_addr;
763 (satosin(&lifr->dstaddr))->sin_addr;
767 * XXXRW: Isn't this priv_check() redundant to the ifnet
770 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
772 sc->g_src.s_addr = INADDR_ANY;
773 sc->g_dst.s_addr = INADDR_ANY;
775 case SIOCGLIFPHYADDR:
776 if (sc->g_src.s_addr == INADDR_ANY ||
777 sc->g_dst.s_addr == INADDR_ANY) {
778 error = EADDRNOTAVAIL;
781 memset(&si, 0, sizeof(si));
782 si.sin_family = AF_INET;
783 si.sin_len = sizeof(struct sockaddr_in);
784 si.sin_addr.s_addr = sc->g_src.s_addr;
785 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
788 memcpy(&lifr->addr, &si, sizeof(si));
789 si.sin_addr.s_addr = sc->g_dst.s_addr;
790 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
793 memcpy(&lifr->dstaddr, &si, sizeof(si));
795 case SIOCGIFPSRCADDR:
797 case SIOCGIFPSRCADDR_IN6:
799 if (sc->g_src.s_addr == INADDR_ANY) {
800 error = EADDRNOTAVAIL;
803 memset(&si, 0, sizeof(si));
804 si.sin_family = AF_INET;
805 si.sin_len = sizeof(struct sockaddr_in);
806 si.sin_addr.s_addr = sc->g_src.s_addr;
807 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
810 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
812 case SIOCGIFPDSTADDR:
814 case SIOCGIFPDSTADDR_IN6:
816 if (sc->g_dst.s_addr == INADDR_ANY) {
817 error = EADDRNOTAVAIL;
820 memset(&si, 0, sizeof(si));
821 si.sin_family = AF_INET;
822 si.sin_len = sizeof(struct sockaddr_in);
823 si.sin_addr.s_addr = sc->g_dst.s_addr;
824 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
827 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
830 error = priv_check(curthread, PRIV_NET_GRE);
833 error = copyin(ifr->ifr_data, &key, sizeof(key));
836 /* adjust MTU for option header */
837 if (key == 0 && sc->key != 0) /* clear */
839 else if (key != 0 && sc->key == 0) /* set */
842 if (ifp->if_mtu + adj < 576) {
850 error = copyout(&sc->key, ifr->ifr_data, sizeof(sc->key));
863 * computes a route to our destination that is not the one
864 * which would be taken by ip_output(), as this one will loop back to
865 * us. If the interface is p2p as a--->b, then a routing entry exists
866 * If we now send a packet to b (e.g. ping b), this will come down here
867 * gets src=a, dst=b tacked on and would from ip_output() sent back to
869 * Goal here is to compute a route to b that is less specific than
870 * a-->b. We know that this one exists as in normal operation we have
871 * at least a default route which matches.
874 gre_compute_route(struct gre_softc *sc)
880 memset(ro, 0, sizeof(struct route));
881 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
882 ro->ro_dst.sa_family = AF_INET;
883 ro->ro_dst.sa_len = sizeof(ro->ro_dst);
886 * toggle last bit, so our interface is not found, but a less
887 * specific route. I'd rather like to specify a shorter mask,
888 * but this is not possible. Should work though. XXX
889 * XXX MRT Use a different FIB for the tunnel to solve this problem.
891 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0) {
892 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr ^=
897 printf("%s: searching for a route to %s", if_name(GRE2IFP(sc)),
898 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
901 rtalloc_fib(ro, sc->gre_fibnum);
904 * check if this returned a route at all and this route is no
905 * recursion to ourself
907 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
909 if (ro->ro_rt == NULL)
910 printf(" - no route found!\n");
912 printf(" - route loops back to ourself!\n");
914 return EADDRNOTAVAIL;
918 * now change it back - else ip_output will just drop
919 * the route and search one to this interface ...
921 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0)
922 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
925 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
926 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
934 * do a checksum of a buffer - much like in_cksum, which operates on
938 gre_in_cksum(u_int16_t *p, u_int len)
941 int nwords = len >> 1;
943 while (nwords-- != 0)
951 u.c[0] = *(u_char *)p;
956 /* end-around-carry */
957 sum = (sum >> 16) + (sum & 0xffff);
963 gremodevent(module_t mod, int type, void *data)
971 if_clone_detach(&gre_cloner);
972 mtx_destroy(&gre_mtx);
980 static moduledata_t gre_mod = {
986 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
987 MODULE_VERSION(if_gre, 1);