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.
22 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
25 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
26 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32 * POSSIBILITY OF SUCH DAMAGE.
36 * Encapsulate L3 protocols into IP
37 * See RFC 2784 (successor of RFC 1701 and 1702) for more details.
38 * If_gre is compatible with Cisco GRE tunnels, so you can
39 * have a NetBSD box as the other end of a tunnel interface of a Cisco
40 * router. See gre(4) for more details.
41 * Also supported: IP in IP encaps (proto 55) as of RFC 2004
44 #include "opt_atalk.h"
46 #include "opt_inet6.h"
48 #include <sys/param.h>
50 #include <sys/kernel.h>
51 #include <sys/libkern.h>
52 #include <sys/malloc.h>
53 #include <sys/module.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>
63 #include <net/ethernet.h>
65 #include <net/if_clone.h>
66 #include <net/if_types.h>
67 #include <net/route.h>
71 #include <netinet/in.h>
72 #include <netinet/in_systm.h>
73 #include <netinet/in_var.h>
74 #include <netinet/ip.h>
75 #include <netinet/ip_gre.h>
76 #include <netinet/ip_var.h>
77 #include <netinet/ip_encap.h>
79 #error "Huh? if_gre without inet?"
84 #include <net/if_gre.h>
87 * It is not easy to calculate the right value for a GRE MTU.
88 * We leave this task to the admin and use the same default that
95 #define MTAG_COOKIE_GRE 1307983903
96 #define MTAG_GRE_NESTING 1
97 struct mtag_gre_nesting {
104 * gre_mtx protects all global variables in if_gre.c.
105 * XXX: gre_softc data not protected yet.
108 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
110 struct gre_softc_head gre_softc_list;
112 static int gre_clone_create(struct if_clone *, int, caddr_t);
113 static void gre_clone_destroy(struct ifnet *);
114 static int gre_ioctl(struct ifnet *, u_long, caddr_t);
115 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
118 IFC_SIMPLE_DECLARE(gre, 0);
120 static int gre_compute_route(struct gre_softc *sc);
122 static void greattach(void);
125 extern struct domain inetdomain;
126 static const struct protosw in_gre_protosw = {
128 .pr_domain = &inetdomain,
129 .pr_protocol = IPPROTO_GRE,
130 .pr_flags = PR_ATOMIC|PR_ADDR,
131 .pr_input = gre_input,
132 .pr_output = (pr_output_t *)rip_output,
133 .pr_ctlinput = rip_ctlinput,
134 .pr_ctloutput = rip_ctloutput,
135 .pr_usrreqs = &rip_usrreqs
137 static const struct protosw in_mobile_protosw = {
139 .pr_domain = &inetdomain,
140 .pr_protocol = IPPROTO_MOBILE,
141 .pr_flags = PR_ATOMIC|PR_ADDR,
142 .pr_input = gre_mobile_input,
143 .pr_output = (pr_output_t *)rip_output,
144 .pr_ctlinput = rip_ctlinput,
145 .pr_ctloutput = rip_ctloutput,
146 .pr_usrreqs = &rip_usrreqs
150 SYSCTL_DECL(_net_link);
151 SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
152 "Generic Routing Encapsulation");
155 * This macro controls the default upper limitation on nesting of gre tunnels.
156 * Since, setting a large value to this macro with a careless configuration
157 * may introduce system crash, we don't allow any nestings by default.
158 * If you need to configure nested gre tunnels, you can define this macro
159 * in your kernel configuration file. However, if you do so, please be
160 * careful to configure the tunnels so that it won't make a loop.
162 #define MAX_GRE_NEST 1
164 static int max_gre_nesting = MAX_GRE_NEST;
165 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
166 &max_gre_nesting, 0, "Max nested tunnels");
173 mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
174 LIST_INIT(&gre_softc_list);
175 if_clone_attach(&gre_cloner);
179 gre_clone_create(ifc, unit, params)
180 struct if_clone *ifc;
184 struct gre_softc *sc;
186 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
188 GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
189 if (GRE2IFP(sc) == NULL) {
194 GRE2IFP(sc)->if_softc = sc;
195 if_initname(GRE2IFP(sc), ifc->ifc_name, unit);
197 GRE2IFP(sc)->if_snd.ifq_maxlen = ifqmaxlen;
198 GRE2IFP(sc)->if_addrlen = 0;
199 GRE2IFP(sc)->if_hdrlen = 24; /* IP + GRE */
200 GRE2IFP(sc)->if_mtu = GREMTU;
201 GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
202 GRE2IFP(sc)->if_output = gre_output;
203 GRE2IFP(sc)->if_ioctl = gre_ioctl;
204 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
205 sc->g_proto = IPPROTO_GRE;
206 GRE2IFP(sc)->if_flags |= IFF_LINK0;
208 sc->gre_fibnum = curthread->td_proc->p_fibnum;
209 sc->wccp_ver = WCCP_V1;
211 if_attach(GRE2IFP(sc));
212 bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
214 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
215 mtx_unlock(&gre_mtx);
220 gre_clone_destroy(ifp)
223 struct gre_softc *sc = ifp->if_softc;
226 LIST_REMOVE(sc, sc_list);
227 mtx_unlock(&gre_mtx);
230 if (sc->encap != NULL)
231 encap_detach(sc->encap);
240 * The output routine. Takes a packet and encapsulates it in the protocol
241 * given by sc->g_proto. See also RFC 1701 and RFC 2004
244 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
248 struct gre_softc *sc = ifp->if_softc;
252 struct mtag_gre_nesting *gt;
254 u_short gre_ip_id = 0;
255 uint8_t gre_ip_tos = 0;
257 struct mobile_h mob_h;
262 * gre may cause infinite recursion calls when misconfigured. High
263 * nesting level may cause stack exhaustion. We'll prevent this by
264 * detecting loops and by introducing upper limit.
266 mtag = m_tag_locate(m, MTAG_COOKIE_GRE, MTAG_GRE_NESTING, NULL);
270 gt = (struct mtag_gre_nesting *)(mtag + 1);
272 if (gt->count > min(gt->max,max_gre_nesting)) {
273 printf("%s: hit maximum recursion limit %u on %s\n",
274 __func__, gt->count - 1, ifp->if_xname);
276 error = EIO; /* is there better errno? */
281 for (max = gt->count - 1; max > 0; max--) {
287 printf("%s: detected loop with nexting %u on %s\n",
288 __func__, gt->count-1, ifp->if_xname);
290 error = EIO; /* is there better errno? */
297 * Given that people should NOT increase max_gre_nesting beyond
298 * their real needs, we allocate once per packet rather than
299 * allocating an mtag once per passing through gre.
301 * Note: the sysctl does not actually check for saneness, so we
302 * limit the maximum numbers of possible recursions here.
304 max = imin(max_gre_nesting, 256);
305 /* If someone sets the sysctl <= 0, we want at least 1. */
307 len = sizeof(struct mtag_gre_nesting) +
308 max * sizeof(struct ifnet *);
309 mtag = m_tag_alloc(MTAG_COOKIE_GRE, MTAG_GRE_NESTING, len,
316 gt = (struct mtag_gre_nesting *)(mtag + 1);
321 m_tag_prepend(m, mtag);
324 if (!((ifp->if_flags & IFF_UP) &&
325 (ifp->if_drv_flags & IFF_DRV_RUNNING)) ||
326 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
335 /* BPF writes need to be handled specially. */
336 if (dst->sa_family == AF_UNSPEC) {
337 bcopy(dst->sa_data, &af, sizeof(af));
341 if (bpf_peers_present(ifp->if_bpf)) {
343 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
346 m->m_flags &= ~(M_BCAST|M_MCAST);
348 if (sc->g_proto == IPPROTO_MOBILE) {
349 if (dst->sa_family == AF_INET) {
353 ip = mtod(m, struct ip *);
356 * RFC2004 specifies that fragmented diagrams shouldn't
359 if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
360 _IF_DROP(&ifp->if_snd);
362 error = EINVAL; /* is there better errno? */
365 memset(&mob_h, 0, MOB_H_SIZ_L);
366 mob_h.proto = (ip->ip_p) << 8;
367 mob_h.odst = ip->ip_dst.s_addr;
368 ip->ip_dst.s_addr = sc->g_dst.s_addr;
371 * If the packet comes from our host, we only change
372 * the destination address in the IP header.
373 * Else we also need to save and change the source
375 if (in_hosteq(ip->ip_src, sc->g_src)) {
378 mob_h.proto |= MOB_H_SBIT;
379 mob_h.osrc = ip->ip_src.s_addr;
380 ip->ip_src.s_addr = sc->g_src.s_addr;
383 mob_h.proto = htons(mob_h.proto);
384 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz);
386 if ((m->m_data - msiz) < m->m_pktdat) {
388 MGETHDR(m0, M_DONTWAIT, MT_DATA);
390 _IF_DROP(&ifp->if_snd);
396 m->m_data += sizeof(struct ip);
397 m->m_len -= sizeof(struct ip);
398 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
399 m0->m_len = msiz + sizeof(struct ip);
400 m0->m_data += max_linkhdr;
401 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
404 } else { /* we have some space left in the old one */
407 m->m_pkthdr.len += msiz;
408 bcopy(ip, mtod(m, caddr_t),
411 ip = mtod(m, struct ip *);
412 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
413 ip->ip_len = ntohs(ip->ip_len) + msiz;
414 } else { /* AF_INET */
415 _IF_DROP(&ifp->if_snd);
420 } else if (sc->g_proto == IPPROTO_GRE) {
421 switch (dst->sa_family) {
423 ip = mtod(m, struct ip *);
424 gre_ip_tos = ip->ip_tos;
425 gre_ip_id = ip->ip_id;
426 if (sc->wccp_ver == WCCP_V2) {
427 extra = sizeof(uint32_t);
428 etype = WCCP_PROTOCOL_TYPE;
430 etype = ETHERTYPE_IP;
435 gre_ip_id = ip_newid();
436 etype = ETHERTYPE_IPV6;
441 etype = ETHERTYPE_ATALK;
445 _IF_DROP(&ifp->if_snd);
447 error = EAFNOSUPPORT;
451 /* Reserve space for GRE header + optional GRE key */
452 int hdrlen = sizeof(struct greip) + extra;
454 hdrlen += sizeof(uint32_t);
455 M_PREPEND(m, hdrlen, M_DONTWAIT);
457 _IF_DROP(&ifp->if_snd);
463 if (m == NULL) { /* mbuf allocation failed */
464 _IF_DROP(&ifp->if_snd);
469 M_SETFIB(m, sc->gre_fibnum); /* The envelope may use a different FIB */
471 gh = mtod(m, struct greip *);
472 if (sc->g_proto == IPPROTO_GRE) {
473 uint32_t *options = gh->gi_options;
475 memset((void *)gh, 0, sizeof(struct greip) + extra);
476 gh->gi_ptype = htons(etype);
482 gh->gi_flags |= htons(GRE_KP);
483 *(options++) = htonl(sc->key);
487 gh->gi_pr = sc->g_proto;
488 if (sc->g_proto != IPPROTO_MOBILE) {
489 gh->gi_src = sc->g_src;
490 gh->gi_dst = sc->g_dst;
491 ((struct ip*)gh)->ip_v = IPPROTO_IPV4;
492 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
493 ((struct ip*)gh)->ip_ttl = GRE_TTL;
494 ((struct ip*)gh)->ip_tos = gre_ip_tos;
495 ((struct ip*)gh)->ip_id = gre_ip_id;
496 gh->gi_len = m->m_pkthdr.len;
500 ifp->if_obytes += m->m_pkthdr.len;
502 * Send it off and with IP_FORWARD flag to prevent it from
503 * overwriting the ip_id again. ip_id is already set to the
504 * ip_id of the encapsulated packet.
506 error = ip_output(m, NULL, &sc->route, IP_FORWARDING,
507 (struct ip_moptions *)NULL, (struct inpcb *)NULL);
515 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
517 struct ifreq *ifr = (struct ifreq *)data;
518 struct if_laddrreq *lifr = (struct if_laddrreq *)data;
519 struct in_aliasreq *aifr = (struct in_aliasreq *)data;
520 struct gre_softc *sc = ifp->if_softc;
522 struct sockaddr_in si;
523 struct sockaddr *sa = NULL;
525 struct sockaddr_in sp, sm, dp, dm;
534 ifp->if_flags |= IFF_UP;
540 * XXXRW: Isn't this priv_check() redundant to the ifnet
543 if ((error = priv_check(curthread, PRIV_NET_SETIFFLAGS)) != 0)
545 if ((ifr->ifr_flags & IFF_LINK0) != 0)
546 sc->g_proto = IPPROTO_GRE;
548 sc->g_proto = IPPROTO_MOBILE;
549 if ((ifr->ifr_flags & IFF_LINK2) != 0)
550 sc->wccp_ver = WCCP_V2;
552 sc->wccp_ver = WCCP_V1;
556 * XXXRW: Isn't this priv_check() redundant to the ifnet
559 if ((error = priv_check(curthread, PRIV_NET_SETIFMTU)) != 0)
561 if (ifr->ifr_mtu < 576) {
565 ifp->if_mtu = ifr->ifr_mtu;
568 ifr->ifr_mtu = GRE2IFP(sc)->if_mtu;
572 * XXXRW: Isn't this priv_checkr() redundant to the ifnet
575 if ((error = priv_check(curthread, PRIV_NET_ADDMULTI)) != 0)
578 error = EAFNOSUPPORT;
581 switch (ifr->ifr_addr.sa_family) {
591 error = EAFNOSUPPORT;
597 * XXXRW: Isn't this priv_check() redundant to the ifnet
600 if ((error = priv_check(curthread, PRIV_NET_DELIFGROUP)) != 0)
603 error = EAFNOSUPPORT;
606 switch (ifr->ifr_addr.sa_family) {
616 error = EAFNOSUPPORT;
622 * XXXRW: Isn't this priv_check() redundant to the ifnet
625 if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
627 sc->g_proto = ifr->ifr_flags;
628 switch (sc->g_proto) {
630 ifp->if_flags |= IFF_LINK0;
633 ifp->if_flags &= ~IFF_LINK0;
636 error = EPROTONOSUPPORT;
641 ifr->ifr_flags = sc->g_proto;
645 error = priv_check(curthread, PRIV_NET_GRE);
649 * set tunnel endpoints, compute a less specific route
650 * to the remote end and mark if as up
653 if (cmd == GRESADDRS)
654 sc->g_src = (satosin(sa))->sin_addr;
655 if (cmd == GRESADDRD)
656 sc->g_dst = (satosin(sa))->sin_addr;
659 if (sc->encap != NULL) {
660 encap_detach(sc->encap);
664 if ((sc->g_src.s_addr != INADDR_ANY) &&
665 (sc->g_dst.s_addr != INADDR_ANY)) {
666 bzero(&sp, sizeof(sp));
667 bzero(&sm, sizeof(sm));
668 bzero(&dp, sizeof(dp));
669 bzero(&dm, sizeof(dm));
670 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
671 sizeof(struct sockaddr_in);
672 sp.sin_family = sm.sin_family = dp.sin_family =
673 dm.sin_family = AF_INET;
674 sp.sin_addr = sc->g_src;
675 dp.sin_addr = sc->g_dst;
676 sm.sin_addr.s_addr = dm.sin_addr.s_addr =
679 sc->encap = encap_attach(AF_INET, sc->g_proto,
680 sintosa(&sp), sintosa(&sm), sintosa(&dp),
681 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
682 &in_gre_protosw : &in_mobile_protosw, sc);
683 if (sc->encap == NULL)
684 printf("%s: unable to attach encap\n",
685 if_name(GRE2IFP(sc)));
687 if (sc->route.ro_rt != 0) /* free old route */
688 RTFREE(sc->route.ro_rt);
689 if (gre_compute_route(sc) == 0)
690 ifp->if_drv_flags |= IFF_DRV_RUNNING;
692 ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
696 memset(&si, 0, sizeof(si));
697 si.sin_family = AF_INET;
698 si.sin_len = sizeof(struct sockaddr_in);
699 si.sin_addr.s_addr = sc->g_src.s_addr;
701 error = prison_if(curthread->td_ucred, sa);
707 memset(&si, 0, sizeof(si));
708 si.sin_family = AF_INET;
709 si.sin_len = sizeof(struct sockaddr_in);
710 si.sin_addr.s_addr = sc->g_dst.s_addr;
712 error = prison_if(curthread->td_ucred, sa);
719 * XXXRW: Isn't this priv_check() redundant to the ifnet
722 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
724 if (aifr->ifra_addr.sin_family != AF_INET ||
725 aifr->ifra_dstaddr.sin_family != AF_INET) {
726 error = EAFNOSUPPORT;
729 if (aifr->ifra_addr.sin_len != sizeof(si) ||
730 aifr->ifra_dstaddr.sin_len != sizeof(si)) {
734 sc->g_src = aifr->ifra_addr.sin_addr;
735 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
737 case SIOCSLIFPHYADDR:
739 * XXXRW: Isn't this priv_check() redundant to the ifnet
742 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
744 if (lifr->addr.ss_family != AF_INET ||
745 lifr->dstaddr.ss_family != AF_INET) {
746 error = EAFNOSUPPORT;
749 if (lifr->addr.ss_len != sizeof(si) ||
750 lifr->dstaddr.ss_len != sizeof(si)) {
754 sc->g_src = (satosin(&lifr->addr))->sin_addr;
756 (satosin(&lifr->dstaddr))->sin_addr;
760 * XXXRW: Isn't this priv_check() redundant to the ifnet
763 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
765 sc->g_src.s_addr = INADDR_ANY;
766 sc->g_dst.s_addr = INADDR_ANY;
768 case SIOCGLIFPHYADDR:
769 if (sc->g_src.s_addr == INADDR_ANY ||
770 sc->g_dst.s_addr == INADDR_ANY) {
771 error = EADDRNOTAVAIL;
774 memset(&si, 0, sizeof(si));
775 si.sin_family = AF_INET;
776 si.sin_len = sizeof(struct sockaddr_in);
777 si.sin_addr.s_addr = sc->g_src.s_addr;
778 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
781 memcpy(&lifr->addr, &si, sizeof(si));
782 si.sin_addr.s_addr = sc->g_dst.s_addr;
783 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
786 memcpy(&lifr->dstaddr, &si, sizeof(si));
788 case SIOCGIFPSRCADDR:
790 case SIOCGIFPSRCADDR_IN6:
792 if (sc->g_src.s_addr == INADDR_ANY) {
793 error = EADDRNOTAVAIL;
796 memset(&si, 0, sizeof(si));
797 si.sin_family = AF_INET;
798 si.sin_len = sizeof(struct sockaddr_in);
799 si.sin_addr.s_addr = sc->g_src.s_addr;
800 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
803 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
805 case SIOCGIFPDSTADDR:
807 case SIOCGIFPDSTADDR_IN6:
809 if (sc->g_dst.s_addr == INADDR_ANY) {
810 error = EADDRNOTAVAIL;
813 memset(&si, 0, sizeof(si));
814 si.sin_family = AF_INET;
815 si.sin_len = sizeof(struct sockaddr_in);
816 si.sin_addr.s_addr = sc->g_dst.s_addr;
817 error = prison_if(curthread->td_ucred, (struct sockaddr *)&si);
820 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
823 error = priv_check(curthread, PRIV_NET_GRE);
826 error = copyin(ifr->ifr_data, &key, sizeof(key));
829 /* adjust MTU for option header */
830 if (key == 0 && sc->key != 0) /* clear */
832 else if (key != 0 && sc->key == 0) /* set */
835 if (ifp->if_mtu + adj < 576) {
843 error = copyout(&sc->key, ifr->ifr_data, sizeof(sc->key));
856 * computes a route to our destination that is not the one
857 * which would be taken by ip_output(), as this one will loop back to
858 * us. If the interface is p2p as a--->b, then a routing entry exists
859 * If we now send a packet to b (e.g. ping b), this will come down here
860 * gets src=a, dst=b tacked on and would from ip_output() sent back to
862 * Goal here is to compute a route to b that is less specific than
863 * a-->b. We know that this one exists as in normal operation we have
864 * at least a default route which matches.
867 gre_compute_route(struct gre_softc *sc)
873 memset(ro, 0, sizeof(struct route));
874 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
875 ro->ro_dst.sa_family = AF_INET;
876 ro->ro_dst.sa_len = sizeof(ro->ro_dst);
879 * toggle last bit, so our interface is not found, but a less
880 * specific route. I'd rather like to specify a shorter mask,
881 * but this is not possible. Should work though. XXX
882 * XXX MRT Use a different FIB for the tunnel to solve this problem.
884 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0) {
885 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr ^=
890 printf("%s: searching for a route to %s", if_name(GRE2IFP(sc)),
891 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
894 rtalloc_fib(ro, sc->gre_fibnum);
897 * check if this returned a route at all and this route is no
898 * recursion to ourself
900 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
902 if (ro->ro_rt == NULL)
903 printf(" - no route found!\n");
905 printf(" - route loops back to ourself!\n");
907 return EADDRNOTAVAIL;
911 * now change it back - else ip_output will just drop
912 * the route and search one to this interface ...
914 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0)
915 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
918 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
919 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
927 * do a checksum of a buffer - much like in_cksum, which operates on
931 gre_in_cksum(u_int16_t *p, u_int len)
934 int nwords = len >> 1;
936 while (nwords-- != 0)
944 u.c[0] = *(u_char *)p;
949 /* end-around-carry */
950 sum = (sum >> 16) + (sum & 0xffff);
956 gremodevent(module_t mod, int type, void *data)
964 if_clone_detach(&gre_cloner);
965 mtx_destroy(&gre_mtx);
973 static moduledata_t gre_mod = {
979 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
980 MODULE_VERSION(if_gre, 1);