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>
56 #include <sys/kernel.h>
57 #include <sys/malloc.h>
58 #include <sys/module.h>
62 #include <sys/protosw.h>
63 #include <sys/socket.h>
64 #include <sys/sockio.h>
65 #include <sys/sysctl.h>
66 #include <sys/systm.h>
68 #include <net/ethernet.h>
70 #include <net/if_clone.h>
71 #include <net/if_types.h>
72 #include <net/route.h>
76 #include <netinet/in.h>
77 #include <netinet/in_systm.h>
78 #include <netinet/in_var.h>
79 #include <netinet/ip.h>
80 #include <netinet/ip_gre.h>
81 #include <netinet/ip_var.h>
82 #include <netinet/ip_encap.h>
84 #error "Huh? if_gre without inet?"
89 #include <net/if_gre.h>
92 * It is not easy to calculate the right value for a GRE MTU.
93 * We leave this task to the admin and use the same default that
101 * gre_mtx protects all global variables in if_gre.c.
102 * XXX: gre_softc data not protected yet.
105 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
107 struct gre_softc_head gre_softc_list;
109 static int gre_clone_create(struct if_clone *, int, caddr_t);
110 static void gre_clone_destroy(struct ifnet *);
111 static int gre_ioctl(struct ifnet *, u_long, caddr_t);
112 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
115 IFC_SIMPLE_DECLARE(gre, 0);
117 static int gre_compute_route(struct gre_softc *sc);
119 static void greattach(void);
122 extern struct domain inetdomain;
123 static const struct protosw in_gre_protosw = {
125 .pr_domain = &inetdomain,
126 .pr_protocol = IPPROTO_GRE,
127 .pr_flags = PR_ATOMIC|PR_ADDR,
128 .pr_input = gre_input,
129 .pr_output = (pr_output_t *)rip_output,
130 .pr_ctlinput = rip_ctlinput,
131 .pr_ctloutput = rip_ctloutput,
132 .pr_usrreqs = &rip_usrreqs
134 static const struct protosw in_mobile_protosw = {
136 .pr_domain = &inetdomain,
137 .pr_protocol = IPPROTO_MOBILE,
138 .pr_flags = PR_ATOMIC|PR_ADDR,
139 .pr_input = gre_mobile_input,
140 .pr_output = (pr_output_t *)rip_output,
141 .pr_ctlinput = rip_ctlinput,
142 .pr_ctloutput = rip_ctloutput,
143 .pr_usrreqs = &rip_usrreqs
147 SYSCTL_DECL(_net_link);
148 SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
149 "Generic Routing Encapsulation");
152 * This macro controls the default upper limitation on nesting of gre tunnels.
153 * Since, setting a large value to this macro with a careless configuration
154 * may introduce system crash, we don't allow any nestings by default.
155 * If you need to configure nested gre tunnels, you can define this macro
156 * in your kernel configuration file. However, if you do so, please be
157 * careful to configure the tunnels so that it won't make a loop.
159 #define MAX_GRE_NEST 1
161 static int max_gre_nesting = MAX_GRE_NEST;
162 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
163 &max_gre_nesting, 0, "Max nested tunnels");
170 mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
171 LIST_INIT(&gre_softc_list);
172 if_clone_attach(&gre_cloner);
176 gre_clone_create(ifc, unit, params)
177 struct if_clone *ifc;
181 struct gre_softc *sc;
183 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
185 GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
186 if (GRE2IFP(sc) == NULL) {
191 GRE2IFP(sc)->if_softc = sc;
192 if_initname(GRE2IFP(sc), ifc->ifc_name, unit);
194 GRE2IFP(sc)->if_snd.ifq_maxlen = ifqmaxlen;
195 GRE2IFP(sc)->if_addrlen = 0;
196 GRE2IFP(sc)->if_hdrlen = 24; /* IP + GRE */
197 GRE2IFP(sc)->if_mtu = GREMTU;
198 GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
199 GRE2IFP(sc)->if_output = gre_output;
200 GRE2IFP(sc)->if_ioctl = gre_ioctl;
201 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
202 sc->g_proto = IPPROTO_GRE;
203 GRE2IFP(sc)->if_flags |= IFF_LINK0;
206 sc->gre_fibnum = curthread->td_proc->p_fibnum;
207 sc->wccp_ver = WCCP_V1;
209 if_attach(GRE2IFP(sc));
210 bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
212 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
213 mtx_unlock(&gre_mtx);
218 gre_clone_destroy(ifp)
221 struct gre_softc *sc = ifp->if_softc;
224 LIST_REMOVE(sc, sc_list);
225 mtx_unlock(&gre_mtx);
228 if (sc->encap != NULL)
229 encap_detach(sc->encap);
238 * The output routine. Takes a packet and encapsulates it in the protocol
239 * given by sc->g_proto. See also RFC 1701 and RFC 2004
242 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
246 struct gre_softc *sc = ifp->if_softc;
249 u_short gre_ip_id = 0;
250 uint8_t gre_ip_tos = 0;
252 struct mobile_h mob_h;
257 * gre may cause infinite recursion calls when misconfigured.
258 * We'll prevent this by introducing upper limit.
260 if (++(sc->called) > max_gre_nesting) {
261 printf("%s: gre_output: recursively called too many "
262 "times(%d)\n", if_name(GRE2IFP(sc)), sc->called);
264 error = EIO; /* is there better errno? */
268 if (!((ifp->if_flags & IFF_UP) &&
269 (ifp->if_drv_flags & IFF_DRV_RUNNING)) ||
270 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
279 /* BPF writes need to be handled specially. */
280 if (dst->sa_family == AF_UNSPEC) {
281 bcopy(dst->sa_data, &af, sizeof(af));
285 if (bpf_peers_present(ifp->if_bpf)) {
287 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
290 m->m_flags &= ~(M_BCAST|M_MCAST);
292 if (sc->g_proto == IPPROTO_MOBILE) {
293 if (dst->sa_family == AF_INET) {
297 ip = mtod(m, struct ip *);
300 * RFC2004 specifies that fragmented diagrams shouldn't
303 if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
304 _IF_DROP(&ifp->if_snd);
306 error = EINVAL; /* is there better errno? */
309 memset(&mob_h, 0, MOB_H_SIZ_L);
310 mob_h.proto = (ip->ip_p) << 8;
311 mob_h.odst = ip->ip_dst.s_addr;
312 ip->ip_dst.s_addr = sc->g_dst.s_addr;
315 * If the packet comes from our host, we only change
316 * the destination address in the IP header.
317 * Else we also need to save and change the source
319 if (in_hosteq(ip->ip_src, sc->g_src)) {
322 mob_h.proto |= MOB_H_SBIT;
323 mob_h.osrc = ip->ip_src.s_addr;
324 ip->ip_src.s_addr = sc->g_src.s_addr;
327 mob_h.proto = htons(mob_h.proto);
328 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz);
330 if ((m->m_data - msiz) < m->m_pktdat) {
332 MGETHDR(m0, M_DONTWAIT, MT_DATA);
334 _IF_DROP(&ifp->if_snd);
340 m->m_data += sizeof(struct ip);
341 m->m_len -= sizeof(struct ip);
342 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
343 m0->m_len = msiz + sizeof(struct ip);
344 m0->m_data += max_linkhdr;
345 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
348 } else { /* we have some space left in the old one */
351 m->m_pkthdr.len += msiz;
352 bcopy(ip, mtod(m, caddr_t),
355 ip = mtod(m, struct ip *);
356 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
357 ip->ip_len = ntohs(ip->ip_len) + msiz;
358 } else { /* AF_INET */
359 _IF_DROP(&ifp->if_snd);
364 } else if (sc->g_proto == IPPROTO_GRE) {
365 switch (dst->sa_family) {
367 ip = mtod(m, struct ip *);
368 gre_ip_tos = ip->ip_tos;
369 gre_ip_id = ip->ip_id;
370 if (sc->wccp_ver == WCCP_V2) {
371 extra = sizeof(uint32_t);
372 etype = WCCP_PROTOCOL_TYPE;
374 etype = ETHERTYPE_IP;
379 gre_ip_id = ip_newid();
380 etype = ETHERTYPE_IPV6;
385 etype = ETHERTYPE_ATALK;
389 _IF_DROP(&ifp->if_snd);
391 error = EAFNOSUPPORT;
395 /* Reserve space for GRE header + optional GRE key */
396 int hdrlen = sizeof(struct greip) + extra;
398 hdrlen += sizeof(uint32_t);
399 M_PREPEND(m, hdrlen, M_DONTWAIT);
401 _IF_DROP(&ifp->if_snd);
407 if (m == NULL) { /* mbuf allocation failed */
408 _IF_DROP(&ifp->if_snd);
413 M_SETFIB(m, sc->gre_fibnum); /* The envelope may use a different FIB */
415 gh = mtod(m, struct greip *);
416 if (sc->g_proto == IPPROTO_GRE) {
417 uint32_t *options = gh->gi_options;
419 memset((void *)gh, 0, sizeof(struct greip) + extra);
420 gh->gi_ptype = htons(etype);
426 gh->gi_flags |= htons(GRE_KP);
427 *(options++) = htonl(sc->key);
431 gh->gi_pr = sc->g_proto;
432 if (sc->g_proto != IPPROTO_MOBILE) {
433 gh->gi_src = sc->g_src;
434 gh->gi_dst = sc->g_dst;
435 ((struct ip*)gh)->ip_v = IPPROTO_IPV4;
436 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
437 ((struct ip*)gh)->ip_ttl = GRE_TTL;
438 ((struct ip*)gh)->ip_tos = gre_ip_tos;
439 ((struct ip*)gh)->ip_id = gre_ip_id;
440 gh->gi_len = m->m_pkthdr.len;
444 ifp->if_obytes += m->m_pkthdr.len;
446 * Send it off and with IP_FORWARD flag to prevent it from
447 * overwriting the ip_id again. ip_id is already set to the
448 * ip_id of the encapsulated packet.
450 error = ip_output(m, NULL, &sc->route, IP_FORWARDING,
451 (struct ip_moptions *)NULL, (struct inpcb *)NULL);
460 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
462 struct ifreq *ifr = (struct ifreq *)data;
463 struct if_laddrreq *lifr = (struct if_laddrreq *)data;
464 struct in_aliasreq *aifr = (struct in_aliasreq *)data;
465 struct gre_softc *sc = ifp->if_softc;
467 struct sockaddr_in si;
468 struct sockaddr *sa = NULL;
470 struct sockaddr_in sp, sm, dp, dm;
479 ifp->if_flags |= IFF_UP;
485 * XXXRW: Isn't this priv_check() redundant to the ifnet
488 if ((error = priv_check(curthread, PRIV_NET_SETIFFLAGS)) != 0)
490 if ((ifr->ifr_flags & IFF_LINK0) != 0)
491 sc->g_proto = IPPROTO_GRE;
493 sc->g_proto = IPPROTO_MOBILE;
494 if ((ifr->ifr_flags & IFF_LINK2) != 0)
495 sc->wccp_ver = WCCP_V2;
497 sc->wccp_ver = WCCP_V1;
501 * XXXRW: Isn't this priv_check() redundant to the ifnet
504 if ((error = priv_check(curthread, PRIV_NET_SETIFMTU)) != 0)
506 if (ifr->ifr_mtu < 576) {
510 ifp->if_mtu = ifr->ifr_mtu;
513 ifr->ifr_mtu = GRE2IFP(sc)->if_mtu;
517 * XXXRW: Isn't this priv_checkr() redundant to the ifnet
520 if ((error = priv_check(curthread, PRIV_NET_ADDMULTI)) != 0)
523 error = EAFNOSUPPORT;
526 switch (ifr->ifr_addr.sa_family) {
536 error = EAFNOSUPPORT;
542 * XXXRW: Isn't this priv_check() redundant to the ifnet
545 if ((error = priv_check(curthread, PRIV_NET_DELIFGROUP)) != 0)
548 error = EAFNOSUPPORT;
551 switch (ifr->ifr_addr.sa_family) {
561 error = EAFNOSUPPORT;
567 * XXXRW: Isn't this priv_check() redundant to the ifnet
570 if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
572 sc->g_proto = ifr->ifr_flags;
573 switch (sc->g_proto) {
575 ifp->if_flags |= IFF_LINK0;
578 ifp->if_flags &= ~IFF_LINK0;
581 error = EPROTONOSUPPORT;
586 ifr->ifr_flags = sc->g_proto;
590 error = priv_check(curthread, PRIV_NET_GRE);
594 * set tunnel endpoints, compute a less specific route
595 * to the remote end and mark if as up
598 if (cmd == GRESADDRS)
599 sc->g_src = (satosin(sa))->sin_addr;
600 if (cmd == GRESADDRD)
601 sc->g_dst = (satosin(sa))->sin_addr;
604 if (sc->encap != NULL) {
605 encap_detach(sc->encap);
609 if ((sc->g_src.s_addr != INADDR_ANY) &&
610 (sc->g_dst.s_addr != INADDR_ANY)) {
611 bzero(&sp, sizeof(sp));
612 bzero(&sm, sizeof(sm));
613 bzero(&dp, sizeof(dp));
614 bzero(&dm, sizeof(dm));
615 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
616 sizeof(struct sockaddr_in);
617 sp.sin_family = sm.sin_family = dp.sin_family =
618 dm.sin_family = AF_INET;
619 sp.sin_addr = sc->g_src;
620 dp.sin_addr = sc->g_dst;
621 sm.sin_addr.s_addr = dm.sin_addr.s_addr =
624 sc->encap = encap_attach(AF_INET, sc->g_proto,
625 sintosa(&sp), sintosa(&sm), sintosa(&dp),
626 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
627 &in_gre_protosw : &in_mobile_protosw, sc);
628 if (sc->encap == NULL)
629 printf("%s: unable to attach encap\n",
630 if_name(GRE2IFP(sc)));
632 if (sc->route.ro_rt != 0) /* free old route */
633 RTFREE(sc->route.ro_rt);
634 if (gre_compute_route(sc) == 0)
635 ifp->if_drv_flags |= IFF_DRV_RUNNING;
637 ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
641 memset(&si, 0, sizeof(si));
642 si.sin_family = AF_INET;
643 si.sin_len = sizeof(struct sockaddr_in);
644 si.sin_addr.s_addr = sc->g_src.s_addr;
649 memset(&si, 0, sizeof(si));
650 si.sin_family = AF_INET;
651 si.sin_len = sizeof(struct sockaddr_in);
652 si.sin_addr.s_addr = sc->g_dst.s_addr;
658 * XXXRW: Isn't this priv_check() redundant to the ifnet
661 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
663 if (aifr->ifra_addr.sin_family != AF_INET ||
664 aifr->ifra_dstaddr.sin_family != AF_INET) {
665 error = EAFNOSUPPORT;
668 if (aifr->ifra_addr.sin_len != sizeof(si) ||
669 aifr->ifra_dstaddr.sin_len != sizeof(si)) {
673 sc->g_src = aifr->ifra_addr.sin_addr;
674 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
676 case SIOCSLIFPHYADDR:
678 * XXXRW: Isn't this priv_check() redundant to the ifnet
681 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
683 if (lifr->addr.ss_family != AF_INET ||
684 lifr->dstaddr.ss_family != AF_INET) {
685 error = EAFNOSUPPORT;
688 if (lifr->addr.ss_len != sizeof(si) ||
689 lifr->dstaddr.ss_len != sizeof(si)) {
693 sc->g_src = (satosin(&lifr->addr))->sin_addr;
695 (satosin(&lifr->dstaddr))->sin_addr;
699 * XXXRW: Isn't this priv_check() redundant to the ifnet
702 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
704 sc->g_src.s_addr = INADDR_ANY;
705 sc->g_dst.s_addr = INADDR_ANY;
707 case SIOCGLIFPHYADDR:
708 if (sc->g_src.s_addr == INADDR_ANY ||
709 sc->g_dst.s_addr == INADDR_ANY) {
710 error = EADDRNOTAVAIL;
713 memset(&si, 0, sizeof(si));
714 si.sin_family = AF_INET;
715 si.sin_len = sizeof(struct sockaddr_in);
716 si.sin_addr.s_addr = sc->g_src.s_addr;
717 memcpy(&lifr->addr, &si, sizeof(si));
718 si.sin_addr.s_addr = sc->g_dst.s_addr;
719 memcpy(&lifr->dstaddr, &si, sizeof(si));
721 case SIOCGIFPSRCADDR:
723 case SIOCGIFPSRCADDR_IN6:
725 if (sc->g_src.s_addr == INADDR_ANY) {
726 error = EADDRNOTAVAIL;
729 memset(&si, 0, sizeof(si));
730 si.sin_family = AF_INET;
731 si.sin_len = sizeof(struct sockaddr_in);
732 si.sin_addr.s_addr = sc->g_src.s_addr;
733 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
735 case SIOCGIFPDSTADDR:
737 case SIOCGIFPDSTADDR_IN6:
739 if (sc->g_dst.s_addr == INADDR_ANY) {
740 error = EADDRNOTAVAIL;
743 memset(&si, 0, sizeof(si));
744 si.sin_family = AF_INET;
745 si.sin_len = sizeof(struct sockaddr_in);
746 si.sin_addr.s_addr = sc->g_dst.s_addr;
747 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
750 error = priv_check(curthread, PRIV_NET_GRE);
753 error = copyin(ifr->ifr_data, &key, sizeof(key));
756 /* adjust MTU for option header */
757 if (key == 0 && sc->key != 0) /* clear */
759 else if (key != 0 && sc->key == 0) /* set */
762 if (ifp->if_mtu + adj < 576) {
770 error = copyout(&sc->key, ifr->ifr_data, sizeof(sc->key));
783 * computes a route to our destination that is not the one
784 * which would be taken by ip_output(), as this one will loop back to
785 * us. If the interface is p2p as a--->b, then a routing entry exists
786 * If we now send a packet to b (e.g. ping b), this will come down here
787 * gets src=a, dst=b tacked on and would from ip_output() sent back to
789 * Goal here is to compute a route to b that is less specific than
790 * a-->b. We know that this one exists as in normal operation we have
791 * at least a default route which matches.
794 gre_compute_route(struct gre_softc *sc)
800 memset(ro, 0, sizeof(struct route));
801 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
802 ro->ro_dst.sa_family = AF_INET;
803 ro->ro_dst.sa_len = sizeof(ro->ro_dst);
806 * toggle last bit, so our interface is not found, but a less
807 * specific route. I'd rather like to specify a shorter mask,
808 * but this is not possible. Should work though. XXX
809 * XXX MRT Use a different FIB for the tunnel to solve this problem.
811 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0) {
812 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr ^=
817 printf("%s: searching for a route to %s", if_name(GRE2IFP(sc)),
818 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
821 rtalloc_fib(ro, sc->gre_fibnum);
824 * check if this returned a route at all and this route is no
825 * recursion to ourself
827 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
829 if (ro->ro_rt == NULL)
830 printf(" - no route found!\n");
832 printf(" - route loops back to ourself!\n");
834 return EADDRNOTAVAIL;
838 * now change it back - else ip_output will just drop
839 * the route and search one to this interface ...
841 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0)
842 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
845 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
846 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
854 * do a checksum of a buffer - much like in_cksum, which operates on
858 gre_in_cksum(u_int16_t *p, u_int len)
861 int nwords = len >> 1;
863 while (nwords-- != 0)
871 u.c[0] = *(u_char *)p;
876 /* end-around-carry */
877 sum = (sum >> 16) + (sum & 0xffff);
883 gremodevent(module_t mod, int type, void *data)
891 if_clone_detach(&gre_cloner);
892 mtx_destroy(&gre_mtx);
900 static moduledata_t gre_mod = {
906 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
907 MODULE_VERSION(if_gre, 1);