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>
49 #include <sys/kernel.h>
50 #include <sys/malloc.h>
51 #include <sys/module.h>
55 #include <sys/protosw.h>
56 #include <sys/socket.h>
57 #include <sys/sockio.h>
58 #include <sys/sysctl.h>
59 #include <sys/systm.h>
61 #include <net/ethernet.h>
63 #include <net/if_clone.h>
64 #include <net/if_types.h>
65 #include <net/route.h>
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>
77 #error "Huh? if_gre without inet?"
82 #include <net/if_gre.h>
85 * It is not easy to calculate the right value for a GRE MTU.
86 * We leave this task to the admin and use the same default that
94 * gre_mtx protects all global variables in if_gre.c.
95 * XXX: gre_softc data not protected yet.
98 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
100 struct gre_softc_head gre_softc_list;
102 static int gre_clone_create(struct if_clone *, int, caddr_t);
103 static void gre_clone_destroy(struct ifnet *);
104 static int gre_ioctl(struct ifnet *, u_long, caddr_t);
105 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
108 IFC_SIMPLE_DECLARE(gre, 0);
110 static int gre_compute_route(struct gre_softc *sc);
112 static void greattach(void);
115 extern struct domain inetdomain;
116 static const struct protosw in_gre_protosw = {
118 .pr_domain = &inetdomain,
119 .pr_protocol = IPPROTO_GRE,
120 .pr_flags = PR_ATOMIC|PR_ADDR,
121 .pr_input = gre_input,
122 .pr_output = (pr_output_t *)rip_output,
123 .pr_ctlinput = rip_ctlinput,
124 .pr_ctloutput = rip_ctloutput,
125 .pr_usrreqs = &rip_usrreqs
127 static const struct protosw in_mobile_protosw = {
129 .pr_domain = &inetdomain,
130 .pr_protocol = IPPROTO_MOBILE,
131 .pr_flags = PR_ATOMIC|PR_ADDR,
132 .pr_input = gre_mobile_input,
133 .pr_output = (pr_output_t *)rip_output,
134 .pr_ctlinput = rip_ctlinput,
135 .pr_ctloutput = rip_ctloutput,
136 .pr_usrreqs = &rip_usrreqs
140 SYSCTL_DECL(_net_link);
141 SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
142 "Generic Routing Encapsulation");
145 * This macro controls the default upper limitation on nesting of gre tunnels.
146 * Since, setting a large value to this macro with a careless configuration
147 * may introduce system crash, we don't allow any nestings by default.
148 * If you need to configure nested gre tunnels, you can define this macro
149 * in your kernel configuration file. However, if you do so, please be
150 * careful to configure the tunnels so that it won't make a loop.
152 #define MAX_GRE_NEST 1
154 static int max_gre_nesting = MAX_GRE_NEST;
155 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
156 &max_gre_nesting, 0, "Max nested tunnels");
163 mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
164 LIST_INIT(&gre_softc_list);
165 if_clone_attach(&gre_cloner);
169 gre_clone_create(ifc, unit, params)
170 struct if_clone *ifc;
174 struct gre_softc *sc;
176 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
178 GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
179 if (GRE2IFP(sc) == NULL) {
184 GRE2IFP(sc)->if_softc = sc;
185 if_initname(GRE2IFP(sc), ifc->ifc_name, unit);
187 GRE2IFP(sc)->if_snd.ifq_maxlen = ifqmaxlen;
188 GRE2IFP(sc)->if_addrlen = 0;
189 GRE2IFP(sc)->if_hdrlen = 24; /* IP + GRE */
190 GRE2IFP(sc)->if_mtu = GREMTU;
191 GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
192 GRE2IFP(sc)->if_output = gre_output;
193 GRE2IFP(sc)->if_ioctl = gre_ioctl;
194 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
195 sc->g_proto = IPPROTO_GRE;
196 GRE2IFP(sc)->if_flags |= IFF_LINK0;
199 sc->gre_fibnum = curthread->td_proc->p_fibnum;
200 sc->wccp_ver = WCCP_V1;
202 if_attach(GRE2IFP(sc));
203 bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
205 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
206 mtx_unlock(&gre_mtx);
211 gre_clone_destroy(ifp)
214 struct gre_softc *sc = ifp->if_softc;
217 LIST_REMOVE(sc, sc_list);
218 mtx_unlock(&gre_mtx);
221 if (sc->encap != NULL)
222 encap_detach(sc->encap);
231 * The output routine. Takes a packet and encapsulates it in the protocol
232 * given by sc->g_proto. See also RFC 1701 and RFC 2004
235 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
239 struct gre_softc *sc = ifp->if_softc;
242 u_short gre_ip_id = 0;
243 uint8_t gre_ip_tos = 0;
245 struct mobile_h mob_h;
250 * gre may cause infinite recursion calls when misconfigured.
251 * We'll prevent this by introducing upper limit.
253 if (++(sc->called) > max_gre_nesting) {
254 printf("%s: gre_output: recursively called too many "
255 "times(%d)\n", if_name(GRE2IFP(sc)), sc->called);
257 error = EIO; /* is there better errno? */
261 if (!((ifp->if_flags & IFF_UP) &&
262 (ifp->if_drv_flags & IFF_DRV_RUNNING)) ||
263 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
272 /* BPF writes need to be handled specially. */
273 if (dst->sa_family == AF_UNSPEC) {
274 bcopy(dst->sa_data, &af, sizeof(af));
278 if (bpf_peers_present(ifp->if_bpf)) {
280 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
283 m->m_flags &= ~(M_BCAST|M_MCAST);
285 if (sc->g_proto == IPPROTO_MOBILE) {
286 if (dst->sa_family == AF_INET) {
290 ip = mtod(m, struct ip *);
293 * RFC2004 specifies that fragmented diagrams shouldn't
296 if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
297 _IF_DROP(&ifp->if_snd);
299 error = EINVAL; /* is there better errno? */
302 memset(&mob_h, 0, MOB_H_SIZ_L);
303 mob_h.proto = (ip->ip_p) << 8;
304 mob_h.odst = ip->ip_dst.s_addr;
305 ip->ip_dst.s_addr = sc->g_dst.s_addr;
308 * If the packet comes from our host, we only change
309 * the destination address in the IP header.
310 * Else we also need to save and change the source
312 if (in_hosteq(ip->ip_src, sc->g_src)) {
315 mob_h.proto |= MOB_H_SBIT;
316 mob_h.osrc = ip->ip_src.s_addr;
317 ip->ip_src.s_addr = sc->g_src.s_addr;
320 mob_h.proto = htons(mob_h.proto);
321 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz);
323 if ((m->m_data - msiz) < m->m_pktdat) {
325 MGETHDR(m0, M_DONTWAIT, MT_DATA);
327 _IF_DROP(&ifp->if_snd);
333 m->m_data += sizeof(struct ip);
334 m->m_len -= sizeof(struct ip);
335 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
336 m0->m_len = msiz + sizeof(struct ip);
337 m0->m_data += max_linkhdr;
338 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
341 } else { /* we have some space left in the old one */
344 m->m_pkthdr.len += msiz;
345 bcopy(ip, mtod(m, caddr_t),
348 ip = mtod(m, struct ip *);
349 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
350 ip->ip_len = ntohs(ip->ip_len) + msiz;
351 } else { /* AF_INET */
352 _IF_DROP(&ifp->if_snd);
357 } else if (sc->g_proto == IPPROTO_GRE) {
358 switch (dst->sa_family) {
360 ip = mtod(m, struct ip *);
361 gre_ip_tos = ip->ip_tos;
362 gre_ip_id = ip->ip_id;
363 if (sc->wccp_ver == WCCP_V2) {
364 extra = sizeof(uint32_t);
365 etype = WCCP_PROTOCOL_TYPE;
367 etype = ETHERTYPE_IP;
372 gre_ip_id = ip_newid();
373 etype = ETHERTYPE_IPV6;
378 etype = ETHERTYPE_ATALK;
382 _IF_DROP(&ifp->if_snd);
384 error = EAFNOSUPPORT;
388 /* Reserve space for GRE header + optional GRE key */
389 int hdrlen = sizeof(struct greip) + extra;
391 hdrlen += sizeof(uint32_t);
392 M_PREPEND(m, hdrlen, M_DONTWAIT);
394 _IF_DROP(&ifp->if_snd);
400 if (m == NULL) { /* mbuf allocation failed */
401 _IF_DROP(&ifp->if_snd);
406 M_SETFIB(m, sc->gre_fibnum); /* The envelope may use a different FIB */
408 gh = mtod(m, struct greip *);
409 if (sc->g_proto == IPPROTO_GRE) {
410 uint32_t *options = gh->gi_options;
412 memset((void *)gh, 0, sizeof(struct greip) + extra);
413 gh->gi_ptype = htons(etype);
419 gh->gi_flags |= htons(GRE_KP);
420 *(options++) = htonl(sc->key);
424 gh->gi_pr = sc->g_proto;
425 if (sc->g_proto != IPPROTO_MOBILE) {
426 gh->gi_src = sc->g_src;
427 gh->gi_dst = sc->g_dst;
428 ((struct ip*)gh)->ip_v = IPPROTO_IPV4;
429 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
430 ((struct ip*)gh)->ip_ttl = GRE_TTL;
431 ((struct ip*)gh)->ip_tos = gre_ip_tos;
432 ((struct ip*)gh)->ip_id = gre_ip_id;
433 gh->gi_len = m->m_pkthdr.len;
437 ifp->if_obytes += m->m_pkthdr.len;
439 * Send it off and with IP_FORWARD flag to prevent it from
440 * overwriting the ip_id again. ip_id is already set to the
441 * ip_id of the encapsulated packet.
443 error = ip_output(m, NULL, &sc->route, IP_FORWARDING,
444 (struct ip_moptions *)NULL, (struct inpcb *)NULL);
453 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
455 struct ifreq *ifr = (struct ifreq *)data;
456 struct if_laddrreq *lifr = (struct if_laddrreq *)data;
457 struct in_aliasreq *aifr = (struct in_aliasreq *)data;
458 struct gre_softc *sc = ifp->if_softc;
460 struct sockaddr_in si;
461 struct sockaddr *sa = NULL;
463 struct sockaddr_in sp, sm, dp, dm;
472 ifp->if_flags |= IFF_UP;
478 * XXXRW: Isn't this priv_check() redundant to the ifnet
481 if ((error = priv_check(curthread, PRIV_NET_SETIFFLAGS)) != 0)
483 if ((ifr->ifr_flags & IFF_LINK0) != 0)
484 sc->g_proto = IPPROTO_GRE;
486 sc->g_proto = IPPROTO_MOBILE;
487 if ((ifr->ifr_flags & IFF_LINK2) != 0)
488 sc->wccp_ver = WCCP_V2;
490 sc->wccp_ver = WCCP_V1;
494 * XXXRW: Isn't this priv_check() redundant to the ifnet
497 if ((error = priv_check(curthread, PRIV_NET_SETIFMTU)) != 0)
499 if (ifr->ifr_mtu < 576) {
503 ifp->if_mtu = ifr->ifr_mtu;
506 ifr->ifr_mtu = GRE2IFP(sc)->if_mtu;
510 * XXXRW: Isn't this priv_checkr() redundant to the ifnet
513 if ((error = priv_check(curthread, PRIV_NET_ADDMULTI)) != 0)
516 error = EAFNOSUPPORT;
519 switch (ifr->ifr_addr.sa_family) {
529 error = EAFNOSUPPORT;
535 * XXXRW: Isn't this priv_check() redundant to the ifnet
538 if ((error = priv_check(curthread, PRIV_NET_DELIFGROUP)) != 0)
541 error = EAFNOSUPPORT;
544 switch (ifr->ifr_addr.sa_family) {
554 error = EAFNOSUPPORT;
560 * XXXRW: Isn't this priv_check() redundant to the ifnet
563 if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
565 sc->g_proto = ifr->ifr_flags;
566 switch (sc->g_proto) {
568 ifp->if_flags |= IFF_LINK0;
571 ifp->if_flags &= ~IFF_LINK0;
574 error = EPROTONOSUPPORT;
579 ifr->ifr_flags = sc->g_proto;
583 error = priv_check(curthread, PRIV_NET_GRE);
587 * set tunnel endpoints, compute a less specific route
588 * to the remote end and mark if as up
591 if (cmd == GRESADDRS)
592 sc->g_src = (satosin(sa))->sin_addr;
593 if (cmd == GRESADDRD)
594 sc->g_dst = (satosin(sa))->sin_addr;
597 if (sc->encap != NULL) {
598 encap_detach(sc->encap);
602 if ((sc->g_src.s_addr != INADDR_ANY) &&
603 (sc->g_dst.s_addr != INADDR_ANY)) {
604 bzero(&sp, sizeof(sp));
605 bzero(&sm, sizeof(sm));
606 bzero(&dp, sizeof(dp));
607 bzero(&dm, sizeof(dm));
608 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
609 sizeof(struct sockaddr_in);
610 sp.sin_family = sm.sin_family = dp.sin_family =
611 dm.sin_family = AF_INET;
612 sp.sin_addr = sc->g_src;
613 dp.sin_addr = sc->g_dst;
614 sm.sin_addr.s_addr = dm.sin_addr.s_addr =
617 sc->encap = encap_attach(AF_INET, sc->g_proto,
618 sintosa(&sp), sintosa(&sm), sintosa(&dp),
619 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
620 &in_gre_protosw : &in_mobile_protosw, sc);
621 if (sc->encap == NULL)
622 printf("%s: unable to attach encap\n",
623 if_name(GRE2IFP(sc)));
625 if (sc->route.ro_rt != 0) /* free old route */
626 RTFREE(sc->route.ro_rt);
627 if (gre_compute_route(sc) == 0)
628 ifp->if_drv_flags |= IFF_DRV_RUNNING;
630 ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
634 memset(&si, 0, sizeof(si));
635 si.sin_family = AF_INET;
636 si.sin_len = sizeof(struct sockaddr_in);
637 si.sin_addr.s_addr = sc->g_src.s_addr;
642 memset(&si, 0, sizeof(si));
643 si.sin_family = AF_INET;
644 si.sin_len = sizeof(struct sockaddr_in);
645 si.sin_addr.s_addr = sc->g_dst.s_addr;
651 * XXXRW: Isn't this priv_check() redundant to the ifnet
654 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
656 if (aifr->ifra_addr.sin_family != AF_INET ||
657 aifr->ifra_dstaddr.sin_family != AF_INET) {
658 error = EAFNOSUPPORT;
661 if (aifr->ifra_addr.sin_len != sizeof(si) ||
662 aifr->ifra_dstaddr.sin_len != sizeof(si)) {
666 sc->g_src = aifr->ifra_addr.sin_addr;
667 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
669 case SIOCSLIFPHYADDR:
671 * XXXRW: Isn't this priv_check() redundant to the ifnet
674 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
676 if (lifr->addr.ss_family != AF_INET ||
677 lifr->dstaddr.ss_family != AF_INET) {
678 error = EAFNOSUPPORT;
681 if (lifr->addr.ss_len != sizeof(si) ||
682 lifr->dstaddr.ss_len != sizeof(si)) {
686 sc->g_src = (satosin(&lifr->addr))->sin_addr;
688 (satosin(&lifr->dstaddr))->sin_addr;
692 * XXXRW: Isn't this priv_check() redundant to the ifnet
695 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
697 sc->g_src.s_addr = INADDR_ANY;
698 sc->g_dst.s_addr = INADDR_ANY;
700 case SIOCGLIFPHYADDR:
701 if (sc->g_src.s_addr == INADDR_ANY ||
702 sc->g_dst.s_addr == INADDR_ANY) {
703 error = EADDRNOTAVAIL;
706 memset(&si, 0, sizeof(si));
707 si.sin_family = AF_INET;
708 si.sin_len = sizeof(struct sockaddr_in);
709 si.sin_addr.s_addr = sc->g_src.s_addr;
710 memcpy(&lifr->addr, &si, sizeof(si));
711 si.sin_addr.s_addr = sc->g_dst.s_addr;
712 memcpy(&lifr->dstaddr, &si, sizeof(si));
714 case SIOCGIFPSRCADDR:
716 case SIOCGIFPSRCADDR_IN6:
718 if (sc->g_src.s_addr == INADDR_ANY) {
719 error = EADDRNOTAVAIL;
722 memset(&si, 0, sizeof(si));
723 si.sin_family = AF_INET;
724 si.sin_len = sizeof(struct sockaddr_in);
725 si.sin_addr.s_addr = sc->g_src.s_addr;
726 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
728 case SIOCGIFPDSTADDR:
730 case SIOCGIFPDSTADDR_IN6:
732 if (sc->g_dst.s_addr == INADDR_ANY) {
733 error = EADDRNOTAVAIL;
736 memset(&si, 0, sizeof(si));
737 si.sin_family = AF_INET;
738 si.sin_len = sizeof(struct sockaddr_in);
739 si.sin_addr.s_addr = sc->g_dst.s_addr;
740 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
743 error = priv_check(curthread, PRIV_NET_GRE);
746 error = copyin(ifr->ifr_data, &key, sizeof(key));
749 /* adjust MTU for option header */
750 if (key == 0 && sc->key != 0) /* clear */
752 else if (key != 0 && sc->key == 0) /* set */
755 if (ifp->if_mtu + adj < 576) {
763 error = copyout(&sc->key, ifr->ifr_data, sizeof(sc->key));
776 * computes a route to our destination that is not the one
777 * which would be taken by ip_output(), as this one will loop back to
778 * us. If the interface is p2p as a--->b, then a routing entry exists
779 * If we now send a packet to b (e.g. ping b), this will come down here
780 * gets src=a, dst=b tacked on and would from ip_output() sent back to
782 * Goal here is to compute a route to b that is less specific than
783 * a-->b. We know that this one exists as in normal operation we have
784 * at least a default route which matches.
787 gre_compute_route(struct gre_softc *sc)
793 memset(ro, 0, sizeof(struct route));
794 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
795 ro->ro_dst.sa_family = AF_INET;
796 ro->ro_dst.sa_len = sizeof(ro->ro_dst);
799 * toggle last bit, so our interface is not found, but a less
800 * specific route. I'd rather like to specify a shorter mask,
801 * but this is not possible. Should work though. XXX
802 * XXX MRT Use a different FIB for the tunnel to solve this problem.
804 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0) {
805 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr ^=
810 printf("%s: searching for a route to %s", if_name(GRE2IFP(sc)),
811 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
814 rtalloc_fib(ro, sc->gre_fibnum);
817 * check if this returned a route at all and this route is no
818 * recursion to ourself
820 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
822 if (ro->ro_rt == NULL)
823 printf(" - no route found!\n");
825 printf(" - route loops back to ourself!\n");
827 return EADDRNOTAVAIL;
831 * now change it back - else ip_output will just drop
832 * the route and search one to this interface ...
834 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0)
835 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
838 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
839 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
847 * do a checksum of a buffer - much like in_cksum, which operates on
851 gre_in_cksum(u_int16_t *p, u_int len)
854 int nwords = len >> 1;
856 while (nwords-- != 0)
864 u.c[0] = *(u_char *)p;
869 /* end-around-carry */
870 sum = (sum >> 16) + (sum & 0xffff);
876 gremodevent(module_t mod, int type, void *data)
884 if_clone_detach(&gre_cloner);
885 mtx_destroy(&gre_mtx);
893 static moduledata_t gre_mod = {
899 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
900 MODULE_VERSION(if_gre, 1);