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ip6_output.c revision 1.61.2.1
      1 /*	$NetBSD: ip6_output.c,v 1.61.2.1 2004/08/03 10:55:13 skrll Exp $	*/
      2 /*	$KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $	*/
      3 
      4 /*
      5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. Neither the name of the project nor the names of its contributors
     17  *    may be used to endorse or promote products derived from this software
     18  *    without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     30  * SUCH DAMAGE.
     31  */
     32 
     33 /*
     34  * Copyright (c) 1982, 1986, 1988, 1990, 1993
     35  *	The Regents of the University of California.  All rights reserved.
     36  *
     37  * Redistribution and use in source and binary forms, with or without
     38  * modification, are permitted provided that the following conditions
     39  * are met:
     40  * 1. Redistributions of source code must retain the above copyright
     41  *    notice, this list of conditions and the following disclaimer.
     42  * 2. Redistributions in binary form must reproduce the above copyright
     43  *    notice, this list of conditions and the following disclaimer in the
     44  *    documentation and/or other materials provided with the distribution.
     45  * 3. Neither the name of the University nor the names of its contributors
     46  *    may be used to endorse or promote products derived from this software
     47  *    without specific prior written permission.
     48  *
     49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     59  * SUCH DAMAGE.
     60  *
     61  *	@(#)ip_output.c	8.3 (Berkeley) 1/21/94
     62  */
     63 
     64 #include <sys/cdefs.h>
     65 __KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.61.2.1 2004/08/03 10:55:13 skrll Exp $");
     66 
     67 #include "opt_inet.h"
     68 #include "opt_ipsec.h"
     69 #include "opt_pfil_hooks.h"
     70 
     71 #include <sys/param.h>
     72 #include <sys/malloc.h>
     73 #include <sys/mbuf.h>
     74 #include <sys/errno.h>
     75 #include <sys/protosw.h>
     76 #include <sys/socket.h>
     77 #include <sys/socketvar.h>
     78 #include <sys/systm.h>
     79 #include <sys/proc.h>
     80 
     81 #include <net/if.h>
     82 #include <net/route.h>
     83 #ifdef PFIL_HOOKS
     84 #include <net/pfil.h>
     85 #endif
     86 
     87 #include <netinet/in.h>
     88 #include <netinet/in_var.h>
     89 #include <netinet/ip6.h>
     90 #include <netinet/icmp6.h>
     91 #include <netinet6/ip6_var.h>
     92 #include <netinet6/in6_pcb.h>
     93 #include <netinet6/nd6.h>
     94 #include <netinet6/ip6protosw.h>
     95 
     96 #ifdef IPSEC
     97 #include <netinet6/ipsec.h>
     98 #include <netkey/key.h>
     99 #endif /* IPSEC */
    100 
    101 #include "loop.h"
    102 
    103 #include <net/net_osdep.h>
    104 
    105 #ifdef PFIL_HOOKS
    106 extern struct pfil_head inet6_pfil_hook;	/* XXX */
    107 #endif
    108 
    109 struct ip6_exthdrs {
    110 	struct mbuf *ip6e_ip6;
    111 	struct mbuf *ip6e_hbh;
    112 	struct mbuf *ip6e_dest1;
    113 	struct mbuf *ip6e_rthdr;
    114 	struct mbuf *ip6e_dest2;
    115 };
    116 
    117 static int ip6_pcbopts __P((struct ip6_pktopts **, struct mbuf *,
    118 	struct socket *));
    119 static int ip6_setmoptions __P((int, struct ip6_moptions **, struct mbuf *));
    120 static int ip6_getmoptions __P((int, struct ip6_moptions *, struct mbuf **));
    121 static int ip6_copyexthdr __P((struct mbuf **, caddr_t, int));
    122 static int ip6_insertfraghdr __P((struct mbuf *, struct mbuf *, int,
    123 	struct ip6_frag **));
    124 static int ip6_insert_jumboopt __P((struct ip6_exthdrs *, u_int32_t));
    125 static int ip6_splithdr __P((struct mbuf *, struct ip6_exthdrs *));
    126 
    127 extern struct ifnet loif[NLOOP];
    128 
    129 /*
    130  * IP6 output. The packet in mbuf chain m contains a skeletal IP6
    131  * header (with pri, len, nxt, hlim, src, dst).
    132  * This function may modify ver and hlim only.
    133  * The mbuf chain containing the packet will be freed.
    134  * The mbuf opt, if present, will not be freed.
    135  *
    136  * type of "mtu": rt_rmx.rmx_mtu is u_long, ifnet.ifr_mtu is int, and
    137  * nd_ifinfo.linkmtu is u_int32_t.  so we use u_long to hold largest one,
    138  * which is rt_rmx.rmx_mtu.
    139  */
    140 int
    141 ip6_output(m0, opt, ro, flags, im6o, so, ifpp)
    142 	struct mbuf *m0;
    143 	struct ip6_pktopts *opt;
    144 	struct route_in6 *ro;
    145 	int flags;
    146 	struct ip6_moptions *im6o;
    147 	struct socket *so;
    148 	struct ifnet **ifpp;		/* XXX: just for statistics */
    149 {
    150 	struct ip6_hdr *ip6, *mhip6;
    151 	struct ifnet *ifp, *origifp;
    152 	struct mbuf *m = m0;
    153 	int hlen, tlen, len, off;
    154 	struct route_in6 ip6route;
    155 	struct sockaddr_in6 *dst;
    156 	int error = 0;
    157 	u_long mtu;
    158 	int alwaysfrag, dontfrag;
    159 	u_int32_t optlen = 0, plen = 0, unfragpartlen = 0;
    160 	struct ip6_exthdrs exthdrs;
    161 	struct in6_addr finaldst;
    162 	struct route_in6 *ro_pmtu = NULL;
    163 	int hdrsplit = 0;
    164 	int needipsec = 0;
    165 #ifdef IPSEC
    166 	int needipsectun = 0;
    167 	struct secpolicy *sp = NULL;
    168 
    169 	ip6 = mtod(m, struct ip6_hdr *);
    170 #endif /* IPSEC */
    171 
    172 #define MAKE_EXTHDR(hp, mp)						\
    173     do {								\
    174 	if (hp) {							\
    175 		struct ip6_ext *eh = (struct ip6_ext *)(hp);		\
    176 		error = ip6_copyexthdr((mp), (caddr_t)(hp), 		\
    177 		    ((eh)->ip6e_len + 1) << 3);				\
    178 		if (error)						\
    179 			goto freehdrs;					\
    180 	}								\
    181     } while (/*CONSTCOND*/ 0)
    182 
    183 	bzero(&exthdrs, sizeof(exthdrs));
    184 	if (opt) {
    185 		/* Hop-by-Hop options header */
    186 		MAKE_EXTHDR(opt->ip6po_hbh, &exthdrs.ip6e_hbh);
    187 		/* Destination options header(1st part) */
    188 		MAKE_EXTHDR(opt->ip6po_dest1, &exthdrs.ip6e_dest1);
    189 		/* Routing header */
    190 		MAKE_EXTHDR(opt->ip6po_rthdr, &exthdrs.ip6e_rthdr);
    191 		/* Destination options header(2nd part) */
    192 		MAKE_EXTHDR(opt->ip6po_dest2, &exthdrs.ip6e_dest2);
    193 	}
    194 
    195 #ifdef IPSEC
    196 	if ((flags & IPV6_FORWARDING) != 0) {
    197 		needipsec = 0;
    198 		goto skippolicycheck;
    199 	}
    200 
    201 	/* get a security policy for this packet */
    202 	if (so == NULL)
    203 		sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error);
    204 	else {
    205 		if (IPSEC_PCB_SKIP_IPSEC(sotoinpcb_hdr(so)->inph_sp,
    206 					 IPSEC_DIR_OUTBOUND)) {
    207 			needipsec = 0;
    208 			goto skippolicycheck;
    209 		}
    210 		sp = ipsec6_getpolicybysock(m, IPSEC_DIR_OUTBOUND, so, &error);
    211 	}
    212 
    213 	if (sp == NULL) {
    214 		ipsec6stat.out_inval++;
    215 		goto freehdrs;
    216 	}
    217 
    218 	error = 0;
    219 
    220 	/* check policy */
    221 	switch (sp->policy) {
    222 	case IPSEC_POLICY_DISCARD:
    223 		/*
    224 		 * This packet is just discarded.
    225 		 */
    226 		ipsec6stat.out_polvio++;
    227 		goto freehdrs;
    228 
    229 	case IPSEC_POLICY_BYPASS:
    230 	case IPSEC_POLICY_NONE:
    231 		/* no need to do IPsec. */
    232 		needipsec = 0;
    233 		break;
    234 
    235 	case IPSEC_POLICY_IPSEC:
    236 		if (sp->req == NULL) {
    237 			/* XXX should be panic ? */
    238 			printf("ip6_output: No IPsec request specified.\n");
    239 			error = EINVAL;
    240 			goto freehdrs;
    241 		}
    242 		needipsec = 1;
    243 		break;
    244 
    245 	case IPSEC_POLICY_ENTRUST:
    246 	default:
    247 		printf("ip6_output: Invalid policy found. %d\n", sp->policy);
    248 	}
    249 
    250   skippolicycheck:;
    251 #endif /* IPSEC */
    252 
    253 	/*
    254 	 * Calculate the total length of the extension header chain.
    255 	 * Keep the length of the unfragmentable part for fragmentation.
    256 	 */
    257 	optlen = 0;
    258 	if (exthdrs.ip6e_hbh) optlen += exthdrs.ip6e_hbh->m_len;
    259 	if (exthdrs.ip6e_dest1) optlen += exthdrs.ip6e_dest1->m_len;
    260 	if (exthdrs.ip6e_rthdr) optlen += exthdrs.ip6e_rthdr->m_len;
    261 	unfragpartlen = optlen + sizeof(struct ip6_hdr);
    262 	/* NOTE: we don't add AH/ESP length here. do that later. */
    263 	if (exthdrs.ip6e_dest2) optlen += exthdrs.ip6e_dest2->m_len;
    264 
    265 	/*
    266 	 * If we need IPsec, or there is at least one extension header,
    267 	 * separate IP6 header from the payload.
    268 	 */
    269 	if ((needipsec || optlen) && !hdrsplit) {
    270 		if ((error = ip6_splithdr(m, &exthdrs)) != 0) {
    271 			m = NULL;
    272 			goto freehdrs;
    273 		}
    274 		m = exthdrs.ip6e_ip6;
    275 		hdrsplit++;
    276 	}
    277 
    278 	/* adjust pointer */
    279 	ip6 = mtod(m, struct ip6_hdr *);
    280 
    281 	/* adjust mbuf packet header length */
    282 	m->m_pkthdr.len += optlen;
    283 	plen = m->m_pkthdr.len - sizeof(*ip6);
    284 
    285 	/* If this is a jumbo payload, insert a jumbo payload option. */
    286 	if (plen > IPV6_MAXPACKET) {
    287 		if (!hdrsplit) {
    288 			if ((error = ip6_splithdr(m, &exthdrs)) != 0) {
    289 				m = NULL;
    290 				goto freehdrs;
    291 			}
    292 			m = exthdrs.ip6e_ip6;
    293 			hdrsplit++;
    294 		}
    295 		/* adjust pointer */
    296 		ip6 = mtod(m, struct ip6_hdr *);
    297 		if ((error = ip6_insert_jumboopt(&exthdrs, plen)) != 0)
    298 			goto freehdrs;
    299 		ip6->ip6_plen = 0;
    300 	} else
    301 		ip6->ip6_plen = htons(plen);
    302 
    303 	/*
    304 	 * Concatenate headers and fill in next header fields.
    305 	 * Here we have, on "m"
    306 	 *	IPv6 payload
    307 	 * and we insert headers accordingly.  Finally, we should be getting:
    308 	 *	IPv6 hbh dest1 rthdr ah* [esp* dest2 payload]
    309 	 *
    310 	 * during the header composing process, "m" points to IPv6 header.
    311 	 * "mprev" points to an extension header prior to esp.
    312 	 */
    313 	{
    314 		u_char *nexthdrp = &ip6->ip6_nxt;
    315 		struct mbuf *mprev = m;
    316 
    317 		/*
    318 		 * we treat dest2 specially.  this makes IPsec processing
    319 		 * much easier.  the goal here is to make mprev point the
    320 		 * mbuf prior to dest2.
    321 		 *
    322 		 * result: IPv6 dest2 payload
    323 		 * m and mprev will point to IPv6 header.
    324 		 */
    325 		if (exthdrs.ip6e_dest2) {
    326 			if (!hdrsplit)
    327 				panic("assumption failed: hdr not split");
    328 			exthdrs.ip6e_dest2->m_next = m->m_next;
    329 			m->m_next = exthdrs.ip6e_dest2;
    330 			*mtod(exthdrs.ip6e_dest2, u_char *) = ip6->ip6_nxt;
    331 			ip6->ip6_nxt = IPPROTO_DSTOPTS;
    332 		}
    333 
    334 #define MAKE_CHAIN(m, mp, p, i)\
    335     do {\
    336 	if (m) {\
    337 		if (!hdrsplit) \
    338 			panic("assumption failed: hdr not split"); \
    339 		*mtod((m), u_char *) = *(p);\
    340 		*(p) = (i);\
    341 		p = mtod((m), u_char *);\
    342 		(m)->m_next = (mp)->m_next;\
    343 		(mp)->m_next = (m);\
    344 		(mp) = (m);\
    345 	}\
    346     } while (/*CONSTCOND*/ 0)
    347 		/*
    348 		 * result: IPv6 hbh dest1 rthdr dest2 payload
    349 		 * m will point to IPv6 header.  mprev will point to the
    350 		 * extension header prior to dest2 (rthdr in the above case).
    351 		 */
    352 		MAKE_CHAIN(exthdrs.ip6e_hbh, mprev, nexthdrp, IPPROTO_HOPOPTS);
    353 		MAKE_CHAIN(exthdrs.ip6e_dest1, mprev, nexthdrp,
    354 		    IPPROTO_DSTOPTS);
    355 		MAKE_CHAIN(exthdrs.ip6e_rthdr, mprev, nexthdrp,
    356 		    IPPROTO_ROUTING);
    357 
    358 #ifdef IPSEC
    359 		if (!needipsec)
    360 			goto skip_ipsec2;
    361 
    362 		/*
    363 		 * pointers after IPsec headers are not valid any more.
    364 		 * other pointers need a great care too.
    365 		 * (IPsec routines should not mangle mbufs prior to AH/ESP)
    366 		 */
    367 		exthdrs.ip6e_dest2 = NULL;
    368 
    369 	    {
    370 		struct ip6_rthdr *rh = NULL;
    371 		int segleft_org = 0;
    372 		struct ipsec_output_state state;
    373 
    374 		if (exthdrs.ip6e_rthdr) {
    375 			rh = mtod(exthdrs.ip6e_rthdr, struct ip6_rthdr *);
    376 			segleft_org = rh->ip6r_segleft;
    377 			rh->ip6r_segleft = 0;
    378 		}
    379 
    380 		bzero(&state, sizeof(state));
    381 		state.m = m;
    382 		error = ipsec6_output_trans(&state, nexthdrp, mprev, sp, flags,
    383 		    &needipsectun);
    384 		m = state.m;
    385 		if (error) {
    386 			/* mbuf is already reclaimed in ipsec6_output_trans. */
    387 			m = NULL;
    388 			switch (error) {
    389 			case EHOSTUNREACH:
    390 			case ENETUNREACH:
    391 			case EMSGSIZE:
    392 			case ENOBUFS:
    393 			case ENOMEM:
    394 				break;
    395 			default:
    396 				printf("ip6_output (ipsec): error code %d\n", error);
    397 				/* FALLTHROUGH */
    398 			case ENOENT:
    399 				/* don't show these error codes to the user */
    400 				error = 0;
    401 				break;
    402 			}
    403 			goto bad;
    404 		}
    405 		if (exthdrs.ip6e_rthdr) {
    406 			/* ah6_output doesn't modify mbuf chain */
    407 			rh->ip6r_segleft = segleft_org;
    408 		}
    409 	    }
    410 skip_ipsec2:;
    411 #endif
    412 	}
    413 
    414 	/*
    415 	 * If there is a routing header, replace destination address field
    416 	 * with the first hop of the routing header.
    417 	 */
    418 	if (exthdrs.ip6e_rthdr) {
    419 		struct ip6_rthdr *rh;
    420 		struct ip6_rthdr0 *rh0;
    421 		struct in6_addr *addr;
    422 
    423 		rh = (struct ip6_rthdr *)(mtod(exthdrs.ip6e_rthdr,
    424 		    struct ip6_rthdr *));
    425 		finaldst = ip6->ip6_dst;
    426 		switch (rh->ip6r_type) {
    427 		case IPV6_RTHDR_TYPE_0:
    428 			 rh0 = (struct ip6_rthdr0 *)rh;
    429 			 addr = (struct in6_addr *)(rh0 + 1);
    430 			 ip6->ip6_dst = addr[0];
    431 			 bcopy(&addr[1], &addr[0],
    432 			     sizeof(struct in6_addr) * (rh0->ip6r0_segleft - 1));
    433 			 addr[rh0->ip6r0_segleft - 1] = finaldst;
    434 			 break;
    435 		default:	/* is it possible? */
    436 			 error = EINVAL;
    437 			 goto bad;
    438 		}
    439 	}
    440 
    441 	/* Source address validation */
    442 	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) &&
    443 	    (flags & IPV6_UNSPECSRC) == 0) {
    444 		error = EOPNOTSUPP;
    445 		ip6stat.ip6s_badscope++;
    446 		goto bad;
    447 	}
    448 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) {
    449 		error = EOPNOTSUPP;
    450 		ip6stat.ip6s_badscope++;
    451 		goto bad;
    452 	}
    453 
    454 	ip6stat.ip6s_localout++;
    455 
    456 	/*
    457 	 * Route packet.
    458 	 */
    459 	/* initialize cached route */
    460 	if (ro == 0) {
    461 		ro = &ip6route;
    462 		bzero((caddr_t)ro, sizeof(*ro));
    463 	}
    464 	ro_pmtu = ro;
    465 	if (opt && opt->ip6po_rthdr)
    466 		ro = &opt->ip6po_route;
    467 	dst = (struct sockaddr_in6 *)&ro->ro_dst;
    468 	/*
    469 	 * If there is a cached route,
    470 	 * check that it is to the same destination
    471 	 * and is still up. If not, free it and try again.
    472 	 */
    473 	if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
    474 	    dst->sin6_family != AF_INET6 ||
    475 	    !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
    476 		RTFREE(ro->ro_rt);
    477 		ro->ro_rt = (struct rtentry *)0;
    478 	}
    479 	if (ro->ro_rt == 0) {
    480 		bzero(dst, sizeof(*dst));
    481 		dst->sin6_family = AF_INET6;
    482 		dst->sin6_len = sizeof(struct sockaddr_in6);
    483 		dst->sin6_addr = ip6->ip6_dst;
    484 	}
    485 #ifdef IPSEC
    486 	if (needipsec && needipsectun) {
    487 		struct ipsec_output_state state;
    488 
    489 		/*
    490 		 * All the extension headers will become inaccessible
    491 		 * (since they can be encrypted).
    492 		 * Don't panic, we need no more updates to extension headers
    493 		 * on inner IPv6 packet (since they are now encapsulated).
    494 		 *
    495 		 * IPv6 [ESP|AH] IPv6 [extension headers] payload
    496 		 */
    497 		bzero(&exthdrs, sizeof(exthdrs));
    498 		exthdrs.ip6e_ip6 = m;
    499 
    500 		bzero(&state, sizeof(state));
    501 		state.m = m;
    502 		state.ro = (struct route *)ro;
    503 		state.dst = (struct sockaddr *)dst;
    504 
    505 		error = ipsec6_output_tunnel(&state, sp, flags);
    506 
    507 		m = state.m;
    508 		ro_pmtu = ro = (struct route_in6 *)state.ro;
    509 		dst = (struct sockaddr_in6 *)state.dst;
    510 		if (error) {
    511 			/* mbuf is already reclaimed in ipsec6_output_tunnel. */
    512 			m0 = m = NULL;
    513 			m = NULL;
    514 			switch (error) {
    515 			case EHOSTUNREACH:
    516 			case ENETUNREACH:
    517 			case EMSGSIZE:
    518 			case ENOBUFS:
    519 			case ENOMEM:
    520 				break;
    521 			default:
    522 				printf("ip6_output (ipsec): error code %d\n", error);
    523 				/* FALLTHROUGH */
    524 			case ENOENT:
    525 				/* don't show these error codes to the user */
    526 				error = 0;
    527 				break;
    528 			}
    529 			goto bad;
    530 		}
    531 
    532 		exthdrs.ip6e_ip6 = m;
    533 	}
    534 #endif /* IPSEC */
    535 
    536 	if (!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
    537 		/* Unicast */
    538 
    539 #define ifatoia6(ifa)	((struct in6_ifaddr *)(ifa))
    540 #define sin6tosa(sin6)	((struct sockaddr *)(sin6))
    541 		/* xxx
    542 		 * interface selection comes here
    543 		 * if an interface is specified from an upper layer,
    544 		 * ifp must point it.
    545 		 */
    546 		if (ro->ro_rt == 0) {
    547 			/*
    548 			 * non-bsdi always clone routes, if parent is
    549 			 * PRF_CLONING.
    550 			 */
    551 			rtalloc((struct route *)ro);
    552 		}
    553 		if (ro->ro_rt == 0) {
    554 			ip6stat.ip6s_noroute++;
    555 			error = EHOSTUNREACH;
    556 			/* XXX in6_ifstat_inc(ifp, ifs6_out_discard); */
    557 			goto bad;
    558 		}
    559 		ifp = ro->ro_rt->rt_ifp;
    560 		ro->ro_rt->rt_use++;
    561 		if (ro->ro_rt->rt_flags & RTF_GATEWAY)
    562 			dst = (struct sockaddr_in6 *)ro->ro_rt->rt_gateway;
    563 		m->m_flags &= ~(M_BCAST | M_MCAST);	/* just in case */
    564 
    565 		in6_ifstat_inc(ifp, ifs6_out_request);
    566 
    567 		/*
    568 		 * Check if the outgoing interface conflicts with
    569 		 * the interface specified by ifi6_ifindex (if specified).
    570 		 * Note that loopback interface is always okay.
    571 		 * (this may happen when we are sending a packet to one of
    572 		 *  our own addresses.)
    573 		 */
    574 		if (opt && opt->ip6po_pktinfo &&
    575 		    opt->ip6po_pktinfo->ipi6_ifindex) {
    576 			if (!(ifp->if_flags & IFF_LOOPBACK) &&
    577 			    ifp->if_index != opt->ip6po_pktinfo->ipi6_ifindex) {
    578 				ip6stat.ip6s_noroute++;
    579 				in6_ifstat_inc(ifp, ifs6_out_discard);
    580 				error = EHOSTUNREACH;
    581 				goto bad;
    582 			}
    583 		}
    584 
    585 		if (opt && opt->ip6po_hlim != -1)
    586 			ip6->ip6_hlim = opt->ip6po_hlim & 0xff;
    587 	} else {
    588 		/* Multicast */
    589 		struct	in6_multi *in6m;
    590 
    591 		m->m_flags = (m->m_flags & ~M_BCAST) | M_MCAST;
    592 
    593 		/*
    594 		 * See if the caller provided any multicast options
    595 		 */
    596 		ifp = NULL;
    597 		if (im6o != NULL) {
    598 			ip6->ip6_hlim = im6o->im6o_multicast_hlim;
    599 			if (im6o->im6o_multicast_ifp != NULL)
    600 				ifp = im6o->im6o_multicast_ifp;
    601 		} else
    602 			ip6->ip6_hlim = ip6_defmcasthlim;
    603 
    604 		/*
    605 		 * See if the caller provided the outgoing interface
    606 		 * as an ancillary data.
    607 		 * Boundary check for ifindex is assumed to be already done.
    608 		 */
    609 		if (opt && opt->ip6po_pktinfo && opt->ip6po_pktinfo->ipi6_ifindex)
    610 			ifp = ifindex2ifnet[opt->ip6po_pktinfo->ipi6_ifindex];
    611 
    612 		/*
    613 		 * If the destination is a node-local scope multicast,
    614 		 * the packet should be loop-backed only.
    615 		 */
    616 		if (IN6_IS_ADDR_MC_NODELOCAL(&ip6->ip6_dst)) {
    617 			/*
    618 			 * If the outgoing interface is already specified,
    619 			 * it should be a loopback interface.
    620 			 */
    621 			if (ifp && (ifp->if_flags & IFF_LOOPBACK) == 0) {
    622 				ip6stat.ip6s_badscope++;
    623 				error = ENETUNREACH; /* XXX: better error? */
    624 				/* XXX correct ifp? */
    625 				in6_ifstat_inc(ifp, ifs6_out_discard);
    626 				goto bad;
    627 			} else {
    628 				ifp = &loif[0];
    629 			}
    630 		}
    631 
    632 		if (opt && opt->ip6po_hlim != -1)
    633 			ip6->ip6_hlim = opt->ip6po_hlim & 0xff;
    634 
    635 		/*
    636 		 * If caller did not provide an interface lookup a
    637 		 * default in the routing table.  This is either a
    638 		 * default for the speicfied group (i.e. a host
    639 		 * route), or a multicast default (a route for the
    640 		 * ``net'' ff00::/8).
    641 		 */
    642 		if (ifp == NULL) {
    643 			if (ro->ro_rt == 0) {
    644 				ro->ro_rt = rtalloc1((struct sockaddr *)
    645 				    &ro->ro_dst, 0);
    646 			}
    647 			if (ro->ro_rt == 0) {
    648 				ip6stat.ip6s_noroute++;
    649 				error = EHOSTUNREACH;
    650 				/* XXX in6_ifstat_inc(ifp, ifs6_out_discard) */
    651 				goto bad;
    652 			}
    653 			ifp = ro->ro_rt->rt_ifp;
    654 			ro->ro_rt->rt_use++;
    655 		}
    656 
    657 		if ((flags & IPV6_FORWARDING) == 0)
    658 			in6_ifstat_inc(ifp, ifs6_out_request);
    659 		in6_ifstat_inc(ifp, ifs6_out_mcast);
    660 
    661 		/*
    662 		 * Confirm that the outgoing interface supports multicast.
    663 		 */
    664 		if ((ifp->if_flags & IFF_MULTICAST) == 0) {
    665 			ip6stat.ip6s_noroute++;
    666 			in6_ifstat_inc(ifp, ifs6_out_discard);
    667 			error = ENETUNREACH;
    668 			goto bad;
    669 		}
    670 		IN6_LOOKUP_MULTI(ip6->ip6_dst, ifp, in6m);
    671 		if (in6m != NULL &&
    672 		   (im6o == NULL || im6o->im6o_multicast_loop)) {
    673 			/*
    674 			 * If we belong to the destination multicast group
    675 			 * on the outgoing interface, and the caller did not
    676 			 * forbid loopback, loop back a copy.
    677 			 */
    678 			ip6_mloopback(ifp, m, dst);
    679 		} else {
    680 			/*
    681 			 * If we are acting as a multicast router, perform
    682 			 * multicast forwarding as if the packet had just
    683 			 * arrived on the interface to which we are about
    684 			 * to send.  The multicast forwarding function
    685 			 * recursively calls this function, using the
    686 			 * IPV6_FORWARDING flag to prevent infinite recursion.
    687 			 *
    688 			 * Multicasts that are looped back by ip6_mloopback(),
    689 			 * above, will be forwarded by the ip6_input() routine,
    690 			 * if necessary.
    691 			 */
    692 			if (ip6_mrouter && (flags & IPV6_FORWARDING) == 0) {
    693 				if (ip6_mforward(ip6, ifp, m) != 0) {
    694 					m_freem(m);
    695 					goto done;
    696 				}
    697 			}
    698 		}
    699 		/*
    700 		 * Multicasts with a hoplimit of zero may be looped back,
    701 		 * above, but must not be transmitted on a network.
    702 		 * Also, multicasts addressed to the loopback interface
    703 		 * are not sent -- the above call to ip6_mloopback() will
    704 		 * loop back a copy if this host actually belongs to the
    705 		 * destination group on the loopback interface.
    706 		 */
    707 		if (ip6->ip6_hlim == 0 || (ifp->if_flags & IFF_LOOPBACK)) {
    708 			m_freem(m);
    709 			goto done;
    710 		}
    711 	}
    712 
    713 	/*
    714 	 * Fill the outgoing inteface to tell the upper layer
    715 	 * to increment per-interface statistics.
    716 	 */
    717 	if (ifpp)
    718 		*ifpp = ifp;
    719 
    720 	/* Determine path MTU. */
    721 	if ((error = ip6_getpmtu(ro_pmtu, ro, ifp, &finaldst, &mtu,
    722 	    &alwaysfrag)) != 0)
    723 		goto bad;
    724 #ifdef IPSEC
    725 	if (needipsectun)
    726 		mtu = IPV6_MMTU;
    727 #endif
    728 
    729 	/*
    730 	 * The caller of this function may specify to use the minimum MTU
    731 	 * in some cases.
    732 	 */
    733 	if (mtu > IPV6_MMTU) {
    734 		if ((flags & IPV6_MINMTU))
    735 			mtu = IPV6_MMTU;
    736 	}
    737 
    738 	/* Fake scoped addresses */
    739 	if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
    740 		/*
    741 		 * If source or destination address is a scoped address, and
    742 		 * the packet is going to be sent to a loopback interface,
    743 		 * we should keep the original interface.
    744 		 */
    745 
    746 		/*
    747 		 * XXX: this is a very experimental and temporary solution.
    748 		 * We eventually have sockaddr_in6 and use the sin6_scope_id
    749 		 * field of the structure here.
    750 		 * We rely on the consistency between two scope zone ids
    751 		 * of source add destination, which should already be assured
    752 		 * Larger scopes than link will be supported in the near
    753 		 * future.
    754 		 */
    755 		origifp = NULL;
    756 		if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
    757 			origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])];
    758 		else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
    759 			origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])];
    760 		/*
    761 		 * XXX: origifp can be NULL even in those two cases above.
    762 		 * For example, if we remove the (only) link-local address
    763 		 * from the loopback interface, and try to send a link-local
    764 		 * address without link-id information.  Then the source
    765 		 * address is ::1, and the destination address is the
    766 		 * link-local address with its s6_addr16[1] being zero.
    767 		 * What is worse, if the packet goes to the loopback interface
    768 		 * by a default rejected route, the null pointer would be
    769 		 * passed to looutput, and the kernel would hang.
    770 		 * The following last resort would prevent such disaster.
    771 		 */
    772 		if (origifp == NULL)
    773 			origifp = ifp;
    774 	} else
    775 		origifp = ifp;
    776 	if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
    777 		ip6->ip6_src.s6_addr16[1] = 0;
    778 	if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
    779 		ip6->ip6_dst.s6_addr16[1] = 0;
    780 
    781 	/*
    782 	 * If the outgoing packet contains a hop-by-hop options header,
    783 	 * it must be examined and processed even by the source node.
    784 	 * (RFC 2460, section 4.)
    785 	 */
    786 	if (exthdrs.ip6e_hbh) {
    787 		struct ip6_hbh *hbh = mtod(exthdrs.ip6e_hbh, struct ip6_hbh *);
    788 		u_int32_t dummy1; /* XXX unused */
    789 		u_int32_t dummy2; /* XXX unused */
    790 
    791 		/*
    792 		 *  XXX: if we have to send an ICMPv6 error to the sender,
    793 		 *       we need the M_LOOP flag since icmp6_error() expects
    794 		 *       the IPv6 and the hop-by-hop options header are
    795 		 *       continuous unless the flag is set.
    796 		 */
    797 		m->m_flags |= M_LOOP;
    798 		m->m_pkthdr.rcvif = ifp;
    799 		if (ip6_process_hopopts(m, (u_int8_t *)(hbh + 1),
    800 		    ((hbh->ip6h_len + 1) << 3) - sizeof(struct ip6_hbh),
    801 		    &dummy1, &dummy2) < 0) {
    802 			/* m was already freed at this point */
    803 			error = EINVAL;/* better error? */
    804 			goto done;
    805 		}
    806 		m->m_flags &= ~M_LOOP; /* XXX */
    807 		m->m_pkthdr.rcvif = NULL;
    808 	}
    809 
    810 #ifdef PFIL_HOOKS
    811 	/*
    812 	 * Run through list of hooks for output packets.
    813 	 */
    814 	if ((error = pfil_run_hooks(&inet6_pfil_hook, &m, ifp, PFIL_OUT)) != 0)
    815 		goto done;
    816 	if (m == NULL)
    817 		goto done;
    818 	ip6 = mtod(m, struct ip6_hdr *);
    819 #endif /* PFIL_HOOKS */
    820 	/*
    821 	 * Send the packet to the outgoing interface.
    822 	 * If necessary, do IPv6 fragmentation before sending.
    823 	 *
    824 	 * the logic here is rather complex:
    825 	 * 1: normal case (dontfrag == 0, alwaysfrag == 0)
    826 	 * 1-a:	send as is if tlen <= path mtu
    827 	 * 1-b:	fragment if tlen > path mtu
    828 	 *
    829 	 * 2: if user asks us not to fragment (dontfrag == 1)
    830 	 * 2-a:	send as is if tlen <= interface mtu
    831 	 * 2-b:	error if tlen > interface mtu
    832 	 *
    833 	 * 3: if we always need to attach fragment header (alwaysfrag == 1)
    834 	 *	always fragment
    835 	 *
    836 	 * 4: if dontfrag == 1 && alwaysfrag == 1
    837 	 *	error, as we cannot handle this conflicting request
    838 	 */
    839 	tlen = m->m_pkthdr.len;
    840 
    841 	dontfrag = 0;
    842 	if (dontfrag && alwaysfrag) {	/* case 4 */
    843 		/* conflicting request - can't transmit */
    844 		error = EMSGSIZE;
    845 		goto bad;
    846 	}
    847 	if (dontfrag && tlen > IN6_LINKMTU(ifp)) {	/* case 2-b */
    848 		/*
    849 		 * Even if the DONTFRAG option is specified, we cannot send the
    850 		 * packet when the data length is larger than the MTU of the
    851 		 * outgoing interface.
    852 		 * Notify the error by sending IPV6_PATHMTU ancillary data as
    853 		 * well as returning an error code (the latter is not described
    854 		 * in the API spec.)
    855 		 */
    856 		u_int32_t mtu32;
    857 		struct ip6ctlparam ip6cp;
    858 
    859 		mtu32 = (u_int32_t)mtu;
    860 		bzero(&ip6cp, sizeof(ip6cp));
    861 		ip6cp.ip6c_cmdarg = (void *)&mtu32;
    862 		pfctlinput2(PRC_MSGSIZE, (struct sockaddr *)&ro_pmtu->ro_dst,
    863 		    (void *)&ip6cp);
    864 
    865 		error = EMSGSIZE;
    866 		goto bad;
    867 	}
    868 
    869 	/*
    870 	 * transmit packet without fragmentation
    871 	 */
    872 	if (dontfrag || (!alwaysfrag && tlen <= mtu)) {	/* case 1-a and 2-a */
    873 		struct in6_ifaddr *ia6;
    874 
    875 		ip6 = mtod(m, struct ip6_hdr *);
    876 		ia6 = in6_ifawithifp(ifp, &ip6->ip6_src);
    877 		if (ia6) {
    878 			/* Record statistics for this interface address. */
    879 			ia6->ia_ifa.ifa_data.ifad_outbytes += m->m_pkthdr.len;
    880 		}
    881 #ifdef IPSEC
    882 		/* clean ipsec history once it goes out of the node */
    883 		ipsec_delaux(m);
    884 #endif
    885 		error = nd6_output(ifp, origifp, m, dst, ro->ro_rt);
    886 		goto done;
    887 	}
    888 
    889 	/*
    890 	 * try to fragment the packet.  case 1-b and 3
    891 	 */
    892 	if (mtu < IPV6_MMTU) {
    893 		/* path MTU cannot be less than IPV6_MMTU */
    894 		error = EMSGSIZE;
    895 		in6_ifstat_inc(ifp, ifs6_out_fragfail);
    896 		goto bad;
    897 	} else if (ip6->ip6_plen == 0) {
    898 		/* jumbo payload cannot be fragmented */
    899 		error = EMSGSIZE;
    900 		in6_ifstat_inc(ifp, ifs6_out_fragfail);
    901 		goto bad;
    902 	} else {
    903 		struct mbuf **mnext, *m_frgpart;
    904 		struct ip6_frag *ip6f;
    905 		u_int32_t id = htonl(ip6_randomid());
    906 		u_char nextproto;
    907 		struct ip6ctlparam ip6cp;
    908 		u_int32_t mtu32;
    909 
    910 		/*
    911 		 * Too large for the destination or interface;
    912 		 * fragment if possible.
    913 		 * Must be able to put at least 8 bytes per fragment.
    914 		 */
    915 		hlen = unfragpartlen;
    916 		if (mtu > IPV6_MAXPACKET)
    917 			mtu = IPV6_MAXPACKET;
    918 
    919 		/* Notify a proper path MTU to applications. */
    920 		mtu32 = (u_int32_t)mtu;
    921 		bzero(&ip6cp, sizeof(ip6cp));
    922 		ip6cp.ip6c_cmdarg = (void *)&mtu32;
    923 		pfctlinput2(PRC_MSGSIZE, (struct sockaddr *)&ro_pmtu->ro_dst,
    924 		    (void *)&ip6cp);
    925 
    926 		len = (mtu - hlen - sizeof(struct ip6_frag)) & ~7;
    927 		if (len < 8) {
    928 			error = EMSGSIZE;
    929 			in6_ifstat_inc(ifp, ifs6_out_fragfail);
    930 			goto bad;
    931 		}
    932 
    933 		mnext = &m->m_nextpkt;
    934 
    935 		/*
    936 		 * Change the next header field of the last header in the
    937 		 * unfragmentable part.
    938 		 */
    939 		if (exthdrs.ip6e_rthdr) {
    940 			nextproto = *mtod(exthdrs.ip6e_rthdr, u_char *);
    941 			*mtod(exthdrs.ip6e_rthdr, u_char *) = IPPROTO_FRAGMENT;
    942 		} else if (exthdrs.ip6e_dest1) {
    943 			nextproto = *mtod(exthdrs.ip6e_dest1, u_char *);
    944 			*mtod(exthdrs.ip6e_dest1, u_char *) = IPPROTO_FRAGMENT;
    945 		} else if (exthdrs.ip6e_hbh) {
    946 			nextproto = *mtod(exthdrs.ip6e_hbh, u_char *);
    947 			*mtod(exthdrs.ip6e_hbh, u_char *) = IPPROTO_FRAGMENT;
    948 		} else {
    949 			nextproto = ip6->ip6_nxt;
    950 			ip6->ip6_nxt = IPPROTO_FRAGMENT;
    951 		}
    952 
    953 		/*
    954 		 * Loop through length of segment after first fragment,
    955 		 * make new header and copy data of each part and link onto
    956 		 * chain.
    957 		 */
    958 		m0 = m;
    959 		for (off = hlen; off < tlen; off += len) {
    960 			struct mbuf *mlast;
    961 
    962 			MGETHDR(m, M_DONTWAIT, MT_HEADER);
    963 			if (!m) {
    964 				error = ENOBUFS;
    965 				ip6stat.ip6s_odropped++;
    966 				goto sendorfree;
    967 			}
    968 			m->m_pkthdr.rcvif = NULL;
    969 			m->m_flags = m0->m_flags & M_COPYFLAGS;
    970 			*mnext = m;
    971 			mnext = &m->m_nextpkt;
    972 			m->m_data += max_linkhdr;
    973 			mhip6 = mtod(m, struct ip6_hdr *);
    974 			*mhip6 = *ip6;
    975 			m->m_len = sizeof(*mhip6);
    976 			error = ip6_insertfraghdr(m0, m, hlen, &ip6f);
    977 			if (error) {
    978 				ip6stat.ip6s_odropped++;
    979 				goto sendorfree;
    980 			}
    981 			ip6f->ip6f_offlg = htons((u_int16_t)((off - hlen) & ~7));
    982 			if (off + len >= tlen)
    983 				len = tlen - off;
    984 			else
    985 				ip6f->ip6f_offlg |= IP6F_MORE_FRAG;
    986 			mhip6->ip6_plen = htons((u_int16_t)(len + hlen +
    987 			    sizeof(*ip6f) - sizeof(struct ip6_hdr)));
    988 			if ((m_frgpart = m_copy(m0, off, len)) == 0) {
    989 				error = ENOBUFS;
    990 				ip6stat.ip6s_odropped++;
    991 				goto sendorfree;
    992 			}
    993 			for (mlast = m; mlast->m_next; mlast = mlast->m_next)
    994 				;
    995 			mlast->m_next = m_frgpart;
    996 			m->m_pkthdr.len = len + hlen + sizeof(*ip6f);
    997 			m->m_pkthdr.rcvif = (struct ifnet *)0;
    998 			ip6f->ip6f_reserved = 0;
    999 			ip6f->ip6f_ident = id;
   1000 			ip6f->ip6f_nxt = nextproto;
   1001 			ip6stat.ip6s_ofragments++;
   1002 			in6_ifstat_inc(ifp, ifs6_out_fragcreat);
   1003 		}
   1004 
   1005 		in6_ifstat_inc(ifp, ifs6_out_fragok);
   1006 	}
   1007 
   1008 	/*
   1009 	 * Remove leading garbages.
   1010 	 */
   1011 sendorfree:
   1012 	m = m0->m_nextpkt;
   1013 	m0->m_nextpkt = 0;
   1014 	m_freem(m0);
   1015 	for (m0 = m; m; m = m0) {
   1016 		m0 = m->m_nextpkt;
   1017 		m->m_nextpkt = 0;
   1018 		if (error == 0) {
   1019 			struct in6_ifaddr *ia6;
   1020 			ip6 = mtod(m, struct ip6_hdr *);
   1021 			ia6 = in6_ifawithifp(ifp, &ip6->ip6_src);
   1022 			if (ia6) {
   1023 				/*
   1024 				 * Record statistics for this interface
   1025 				 * address.
   1026 				 */
   1027 				ia6->ia_ifa.ifa_data.ifad_outbytes +=
   1028 				    m->m_pkthdr.len;
   1029 			}
   1030 #ifdef IPSEC
   1031 			/* clean ipsec history once it goes out of the node */
   1032 			ipsec_delaux(m);
   1033 #endif
   1034 			error = nd6_output(ifp, origifp, m, dst, ro->ro_rt);
   1035 		} else
   1036 			m_freem(m);
   1037 	}
   1038 
   1039 	if (error == 0)
   1040 		ip6stat.ip6s_fragmented++;
   1041 
   1042 done:
   1043 	if (ro == &ip6route && ro->ro_rt) { /* brace necessary for RTFREE */
   1044 		RTFREE(ro->ro_rt);
   1045 	} else if (ro_pmtu == &ip6route && ro_pmtu->ro_rt) {
   1046 		RTFREE(ro_pmtu->ro_rt);
   1047 	}
   1048 
   1049 #ifdef IPSEC
   1050 	if (sp != NULL)
   1051 		key_freesp(sp);
   1052 #endif /* IPSEC */
   1053 
   1054 	return (error);
   1055 
   1056 freehdrs:
   1057 	m_freem(exthdrs.ip6e_hbh);	/* m_freem will check if mbuf is 0 */
   1058 	m_freem(exthdrs.ip6e_dest1);
   1059 	m_freem(exthdrs.ip6e_rthdr);
   1060 	m_freem(exthdrs.ip6e_dest2);
   1061 	/* FALLTHROUGH */
   1062 bad:
   1063 	m_freem(m);
   1064 	goto done;
   1065 }
   1066 
   1067 static int
   1068 ip6_copyexthdr(mp, hdr, hlen)
   1069 	struct mbuf **mp;
   1070 	caddr_t hdr;
   1071 	int hlen;
   1072 {
   1073 	struct mbuf *m;
   1074 
   1075 	if (hlen > MCLBYTES)
   1076 		return (ENOBUFS); /* XXX */
   1077 
   1078 	MGET(m, M_DONTWAIT, MT_DATA);
   1079 	if (!m)
   1080 		return (ENOBUFS);
   1081 
   1082 	if (hlen > MLEN) {
   1083 		MCLGET(m, M_DONTWAIT);
   1084 		if ((m->m_flags & M_EXT) == 0) {
   1085 			m_free(m);
   1086 			return (ENOBUFS);
   1087 		}
   1088 	}
   1089 	m->m_len = hlen;
   1090 	if (hdr)
   1091 		bcopy(hdr, mtod(m, caddr_t), hlen);
   1092 
   1093 	*mp = m;
   1094 	return (0);
   1095 }
   1096 
   1097 /*
   1098  * Insert jumbo payload option.
   1099  */
   1100 static int
   1101 ip6_insert_jumboopt(exthdrs, plen)
   1102 	struct ip6_exthdrs *exthdrs;
   1103 	u_int32_t plen;
   1104 {
   1105 	struct mbuf *mopt;
   1106 	u_int8_t *optbuf;
   1107 	u_int32_t v;
   1108 
   1109 #define JUMBOOPTLEN	8	/* length of jumbo payload option and padding */
   1110 
   1111 	/*
   1112 	 * If there is no hop-by-hop options header, allocate new one.
   1113 	 * If there is one but it doesn't have enough space to store the
   1114 	 * jumbo payload option, allocate a cluster to store the whole options.
   1115 	 * Otherwise, use it to store the options.
   1116 	 */
   1117 	if (exthdrs->ip6e_hbh == 0) {
   1118 		MGET(mopt, M_DONTWAIT, MT_DATA);
   1119 		if (mopt == 0)
   1120 			return (ENOBUFS);
   1121 		mopt->m_len = JUMBOOPTLEN;
   1122 		optbuf = mtod(mopt, u_int8_t *);
   1123 		optbuf[1] = 0;	/* = ((JUMBOOPTLEN) >> 3) - 1 */
   1124 		exthdrs->ip6e_hbh = mopt;
   1125 	} else {
   1126 		struct ip6_hbh *hbh;
   1127 
   1128 		mopt = exthdrs->ip6e_hbh;
   1129 		if (M_TRAILINGSPACE(mopt) < JUMBOOPTLEN) {
   1130 			/*
   1131 			 * XXX assumption:
   1132 			 * - exthdrs->ip6e_hbh is not referenced from places
   1133 			 *   other than exthdrs.
   1134 			 * - exthdrs->ip6e_hbh is not an mbuf chain.
   1135 			 */
   1136 			int oldoptlen = mopt->m_len;
   1137 			struct mbuf *n;
   1138 
   1139 			/*
   1140 			 * XXX: give up if the whole (new) hbh header does
   1141 			 * not fit even in an mbuf cluster.
   1142 			 */
   1143 			if (oldoptlen + JUMBOOPTLEN > MCLBYTES)
   1144 				return (ENOBUFS);
   1145 
   1146 			/*
   1147 			 * As a consequence, we must always prepare a cluster
   1148 			 * at this point.
   1149 			 */
   1150 			MGET(n, M_DONTWAIT, MT_DATA);
   1151 			if (n) {
   1152 				MCLGET(n, M_DONTWAIT);
   1153 				if ((n->m_flags & M_EXT) == 0) {
   1154 					m_freem(n);
   1155 					n = NULL;
   1156 				}
   1157 			}
   1158 			if (!n)
   1159 				return (ENOBUFS);
   1160 			n->m_len = oldoptlen + JUMBOOPTLEN;
   1161 			bcopy(mtod(mopt, caddr_t), mtod(n, caddr_t),
   1162 			    oldoptlen);
   1163 			optbuf = mtod(n, u_int8_t *) + oldoptlen;
   1164 			m_freem(mopt);
   1165 			mopt = exthdrs->ip6e_hbh = n;
   1166 		} else {
   1167 			optbuf = mtod(mopt, u_int8_t *) + mopt->m_len;
   1168 			mopt->m_len += JUMBOOPTLEN;
   1169 		}
   1170 		optbuf[0] = IP6OPT_PADN;
   1171 		optbuf[1] = 0;
   1172 
   1173 		/*
   1174 		 * Adjust the header length according to the pad and
   1175 		 * the jumbo payload option.
   1176 		 */
   1177 		hbh = mtod(mopt, struct ip6_hbh *);
   1178 		hbh->ip6h_len += (JUMBOOPTLEN >> 3);
   1179 	}
   1180 
   1181 	/* fill in the option. */
   1182 	optbuf[2] = IP6OPT_JUMBO;
   1183 	optbuf[3] = 4;
   1184 	v = (u_int32_t)htonl(plen + JUMBOOPTLEN);
   1185 	bcopy(&v, &optbuf[4], sizeof(u_int32_t));
   1186 
   1187 	/* finally, adjust the packet header length */
   1188 	exthdrs->ip6e_ip6->m_pkthdr.len += JUMBOOPTLEN;
   1189 
   1190 	return (0);
   1191 #undef JUMBOOPTLEN
   1192 }
   1193 
   1194 /*
   1195  * Insert fragment header and copy unfragmentable header portions.
   1196  */
   1197 static int
   1198 ip6_insertfraghdr(m0, m, hlen, frghdrp)
   1199 	struct mbuf *m0, *m;
   1200 	int hlen;
   1201 	struct ip6_frag **frghdrp;
   1202 {
   1203 	struct mbuf *n, *mlast;
   1204 
   1205 	if (hlen > sizeof(struct ip6_hdr)) {
   1206 		n = m_copym(m0, sizeof(struct ip6_hdr),
   1207 		    hlen - sizeof(struct ip6_hdr), M_DONTWAIT);
   1208 		if (n == 0)
   1209 			return (ENOBUFS);
   1210 		m->m_next = n;
   1211 	} else
   1212 		n = m;
   1213 
   1214 	/* Search for the last mbuf of unfragmentable part. */
   1215 	for (mlast = n; mlast->m_next; mlast = mlast->m_next)
   1216 		;
   1217 
   1218 	if ((mlast->m_flags & M_EXT) == 0 &&
   1219 	    M_TRAILINGSPACE(mlast) >= sizeof(struct ip6_frag)) {
   1220 		/* use the trailing space of the last mbuf for the fragment hdr */
   1221 		*frghdrp = (struct ip6_frag *)(mtod(mlast, caddr_t) +
   1222 		    mlast->m_len);
   1223 		mlast->m_len += sizeof(struct ip6_frag);
   1224 		m->m_pkthdr.len += sizeof(struct ip6_frag);
   1225 	} else {
   1226 		/* allocate a new mbuf for the fragment header */
   1227 		struct mbuf *mfrg;
   1228 
   1229 		MGET(mfrg, M_DONTWAIT, MT_DATA);
   1230 		if (mfrg == 0)
   1231 			return (ENOBUFS);
   1232 		mfrg->m_len = sizeof(struct ip6_frag);
   1233 		*frghdrp = mtod(mfrg, struct ip6_frag *);
   1234 		mlast->m_next = mfrg;
   1235 	}
   1236 
   1237 	return (0);
   1238 }
   1239 
   1240 int
   1241 ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup, alwaysfragp)
   1242 	struct route_in6 *ro_pmtu, *ro;
   1243 	struct ifnet *ifp;
   1244 	struct in6_addr *dst;
   1245 	u_long *mtup;
   1246 	int *alwaysfragp;
   1247 {
   1248 	u_int32_t mtu = 0;
   1249 	int alwaysfrag = 0;
   1250 	int error = 0;
   1251 
   1252 	if (ro_pmtu != ro) {
   1253 		/* The first hop and the final destination may differ. */
   1254 		struct sockaddr_in6 *sa6_dst =
   1255 		    (struct sockaddr_in6 *)&ro_pmtu->ro_dst;
   1256 		if (ro_pmtu->ro_rt &&
   1257 		    ((ro_pmtu->ro_rt->rt_flags & RTF_UP) == 0 ||
   1258 		      !IN6_ARE_ADDR_EQUAL(&sa6_dst->sin6_addr, dst))) {
   1259 			RTFREE(ro_pmtu->ro_rt);
   1260 			ro_pmtu->ro_rt = (struct rtentry *)NULL;
   1261 		}
   1262 		if (ro_pmtu->ro_rt == NULL) {
   1263 			bzero(sa6_dst, sizeof(*sa6_dst)); /* for safety */
   1264 			sa6_dst->sin6_family = AF_INET6;
   1265 			sa6_dst->sin6_len = sizeof(struct sockaddr_in6);
   1266 			sa6_dst->sin6_addr = *dst;
   1267 
   1268 			rtalloc((struct route *)ro_pmtu);
   1269 		}
   1270 	}
   1271 	if (ro_pmtu->ro_rt) {
   1272 		u_int32_t ifmtu;
   1273 
   1274 		if (ifp == NULL)
   1275 			ifp = ro_pmtu->ro_rt->rt_ifp;
   1276 		ifmtu = IN6_LINKMTU(ifp);
   1277 		mtu = ro_pmtu->ro_rt->rt_rmx.rmx_mtu;
   1278 		if (mtu == 0)
   1279 			mtu = ifmtu;
   1280 		else if (mtu < IPV6_MMTU) {
   1281 			/*
   1282 			 * RFC2460 section 5, last paragraph:
   1283 			 * if we record ICMPv6 too big message with
   1284 			 * mtu < IPV6_MMTU, transmit packets sized IPV6_MMTU
   1285 			 * or smaller, with fragment header attached.
   1286 			 * (fragment header is needed regardless from the
   1287 			 * packet size, for translators to identify packets)
   1288 			 */
   1289 			alwaysfrag = 1;
   1290 			mtu = IPV6_MMTU;
   1291 		} else if (mtu > ifmtu) {
   1292 			/*
   1293 			 * The MTU on the route is larger than the MTU on
   1294 			 * the interface!  This shouldn't happen, unless the
   1295 			 * MTU of the interface has been changed after the
   1296 			 * interface was brought up.  Change the MTU in the
   1297 			 * route to match the interface MTU (as long as the
   1298 			 * field isn't locked).
   1299 			 */
   1300 			mtu = ifmtu;
   1301 			if (!(ro_pmtu->ro_rt->rt_rmx.rmx_locks & RTV_MTU))
   1302 				ro_pmtu->ro_rt->rt_rmx.rmx_mtu = mtu;
   1303 		}
   1304 	} else if (ifp) {
   1305 		mtu = IN6_LINKMTU(ifp);
   1306 	} else
   1307 		error = EHOSTUNREACH; /* XXX */
   1308 
   1309 	*mtup = mtu;
   1310 	if (alwaysfragp)
   1311 		*alwaysfragp = alwaysfrag;
   1312 	return (error);
   1313 }
   1314 
   1315 /*
   1316  * IP6 socket option processing.
   1317  */
   1318 int
   1319 ip6_ctloutput(op, so, level, optname, mp)
   1320 	int op;
   1321 	struct socket *so;
   1322 	int level, optname;
   1323 	struct mbuf **mp;
   1324 {
   1325 	struct in6pcb *in6p = sotoin6pcb(so);
   1326 	struct mbuf *m = *mp;
   1327 	int optval = 0;
   1328 	int error = 0;
   1329 	struct proc *p = curproc;	/* XXX */
   1330 
   1331 	if (level == IPPROTO_IPV6) {
   1332 		switch (op) {
   1333 		case PRCO_SETOPT:
   1334 			switch (optname) {
   1335 			case IPV6_PKTOPTIONS:
   1336 				/* m is freed in ip6_pcbopts */
   1337 				return (ip6_pcbopts(&in6p->in6p_outputopts,
   1338 				    m, so));
   1339 			case IPV6_HOPOPTS:
   1340 			case IPV6_DSTOPTS:
   1341 				if (p == 0 || suser(p->p_ucred, &p->p_acflag)) {
   1342 					error = EPERM;
   1343 					break;
   1344 				}
   1345 				/* FALLTHROUGH */
   1346 			case IPV6_UNICAST_HOPS:
   1347 			case IPV6_RECVOPTS:
   1348 			case IPV6_RECVRETOPTS:
   1349 			case IPV6_RECVDSTADDR:
   1350 			case IPV6_PKTINFO:
   1351 			case IPV6_HOPLIMIT:
   1352 			case IPV6_RTHDR:
   1353 			case IPV6_FAITH:
   1354 			case IPV6_V6ONLY:
   1355 			case IPV6_USE_MIN_MTU:
   1356 				if (!m || m->m_len != sizeof(int)) {
   1357 					error = EINVAL;
   1358 					break;
   1359 				}
   1360 				optval = *mtod(m, int *);
   1361 				switch (optname) {
   1362 
   1363 				case IPV6_UNICAST_HOPS:
   1364 					if (optval < -1 || optval >= 256)
   1365 						error = EINVAL;
   1366 					else {
   1367 						/* -1 = kernel default */
   1368 						in6p->in6p_hops = optval;
   1369 					}
   1370 					break;
   1371 #define OPTSET(bit) \
   1372 do { \
   1373 	if (optval) \
   1374 		in6p->in6p_flags |= (bit); \
   1375 	else \
   1376 		in6p->in6p_flags &= ~(bit); \
   1377 } while (/*CONSTCOND*/ 0)
   1378 
   1379 				case IPV6_RECVOPTS:
   1380 					OPTSET(IN6P_RECVOPTS);
   1381 					break;
   1382 
   1383 				case IPV6_RECVRETOPTS:
   1384 					OPTSET(IN6P_RECVRETOPTS);
   1385 					break;
   1386 
   1387 				case IPV6_RECVDSTADDR:
   1388 					OPTSET(IN6P_RECVDSTADDR);
   1389 					break;
   1390 
   1391 				case IPV6_PKTINFO:
   1392 					OPTSET(IN6P_PKTINFO);
   1393 					break;
   1394 
   1395 				case IPV6_HOPLIMIT:
   1396 					OPTSET(IN6P_HOPLIMIT);
   1397 					break;
   1398 
   1399 				case IPV6_HOPOPTS:
   1400 					OPTSET(IN6P_HOPOPTS);
   1401 					break;
   1402 
   1403 				case IPV6_DSTOPTS:
   1404 					OPTSET(IN6P_DSTOPTS);
   1405 					break;
   1406 
   1407 				case IPV6_RTHDR:
   1408 					OPTSET(IN6P_RTHDR);
   1409 					break;
   1410 
   1411 				case IPV6_FAITH:
   1412 					OPTSET(IN6P_FAITH);
   1413 					break;
   1414 
   1415 				case IPV6_USE_MIN_MTU:
   1416 					OPTSET(IN6P_MINMTU);
   1417 					break;
   1418 
   1419 				case IPV6_V6ONLY:
   1420 					/*
   1421 					 * make setsockopt(IPV6_V6ONLY)
   1422 					 * available only prior to bind(2).
   1423 					 * see ipng mailing list, Jun 22 2001.
   1424 					 */
   1425 					if (in6p->in6p_lport ||
   1426 					    !IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_laddr)) {
   1427 						error = EINVAL;
   1428 						break;
   1429 					}
   1430 #ifdef INET6_BINDV6ONLY
   1431 					if (!optval)
   1432 						error = EINVAL;
   1433 #else
   1434 					OPTSET(IN6P_IPV6_V6ONLY);
   1435 #endif
   1436 					break;
   1437 				}
   1438 				break;
   1439 #undef OPTSET
   1440 
   1441 			case IPV6_MULTICAST_IF:
   1442 			case IPV6_MULTICAST_HOPS:
   1443 			case IPV6_MULTICAST_LOOP:
   1444 			case IPV6_JOIN_GROUP:
   1445 			case IPV6_LEAVE_GROUP:
   1446 				error =	ip6_setmoptions(optname,
   1447 				    &in6p->in6p_moptions, m);
   1448 				break;
   1449 
   1450 			case IPV6_PORTRANGE:
   1451 				optval = *mtod(m, int *);
   1452 
   1453 				switch (optval) {
   1454 				case IPV6_PORTRANGE_DEFAULT:
   1455 					in6p->in6p_flags &= ~(IN6P_LOWPORT);
   1456 					in6p->in6p_flags &= ~(IN6P_HIGHPORT);
   1457 					break;
   1458 
   1459 				case IPV6_PORTRANGE_HIGH:
   1460 					in6p->in6p_flags &= ~(IN6P_LOWPORT);
   1461 					in6p->in6p_flags |= IN6P_HIGHPORT;
   1462 					break;
   1463 
   1464 				case IPV6_PORTRANGE_LOW:
   1465 					in6p->in6p_flags &= ~(IN6P_HIGHPORT);
   1466 					in6p->in6p_flags |= IN6P_LOWPORT;
   1467 					break;
   1468 
   1469 				default:
   1470 					error = EINVAL;
   1471 					break;
   1472 				}
   1473 				break;
   1474 
   1475 #ifdef IPSEC
   1476 			case IPV6_IPSEC_POLICY:
   1477 			    {
   1478 				caddr_t req = NULL;
   1479 				size_t len = 0;
   1480 
   1481 				int priv = 0;
   1482 				if (p == 0 || suser(p->p_ucred, &p->p_acflag))
   1483 					priv = 0;
   1484 				else
   1485 					priv = 1;
   1486 				if (m) {
   1487 					req = mtod(m, caddr_t);
   1488 					len = m->m_len;
   1489 				}
   1490 				error = ipsec6_set_policy(in6p,
   1491 				                   optname, req, len, priv);
   1492 			    }
   1493 				break;
   1494 #endif /* IPSEC */
   1495 
   1496 			default:
   1497 				error = ENOPROTOOPT;
   1498 				break;
   1499 			}
   1500 			if (m)
   1501 				(void)m_free(m);
   1502 			break;
   1503 
   1504 		case PRCO_GETOPT:
   1505 			switch (optname) {
   1506 
   1507 			case IPV6_OPTIONS:
   1508 			case IPV6_RETOPTS:
   1509 				error = ENOPROTOOPT;
   1510 				break;
   1511 
   1512 			case IPV6_PKTOPTIONS:
   1513 				if (in6p->in6p_options) {
   1514 					*mp = m_copym(in6p->in6p_options, 0,
   1515 					    M_COPYALL, M_WAIT);
   1516 				} else {
   1517 					*mp = m_get(M_WAIT, MT_SOOPTS);
   1518 					(*mp)->m_len = 0;
   1519 				}
   1520 				break;
   1521 
   1522 			case IPV6_HOPOPTS:
   1523 			case IPV6_DSTOPTS:
   1524 				if (p == 0 || suser(p->p_ucred, &p->p_acflag)) {
   1525 					error = EPERM;
   1526 					break;
   1527 				}
   1528 				/* FALLTHROUGH */
   1529 			case IPV6_UNICAST_HOPS:
   1530 			case IPV6_RECVOPTS:
   1531 			case IPV6_RECVRETOPTS:
   1532 			case IPV6_RECVDSTADDR:
   1533 			case IPV6_PORTRANGE:
   1534 			case IPV6_PKTINFO:
   1535 			case IPV6_HOPLIMIT:
   1536 			case IPV6_RTHDR:
   1537 			case IPV6_FAITH:
   1538 			case IPV6_V6ONLY:
   1539 			case IPV6_USE_MIN_MTU:
   1540 				*mp = m = m_get(M_WAIT, MT_SOOPTS);
   1541 				m->m_len = sizeof(int);
   1542 				switch (optname) {
   1543 
   1544 				case IPV6_UNICAST_HOPS:
   1545 					optval = in6p->in6p_hops;
   1546 					break;
   1547 
   1548 #define OPTBIT(bit) (in6p->in6p_flags & bit ? 1 : 0)
   1549 
   1550 				case IPV6_RECVOPTS:
   1551 					optval = OPTBIT(IN6P_RECVOPTS);
   1552 					break;
   1553 
   1554 				case IPV6_RECVRETOPTS:
   1555 					optval = OPTBIT(IN6P_RECVRETOPTS);
   1556 					break;
   1557 
   1558 				case IPV6_RECVDSTADDR:
   1559 					optval = OPTBIT(IN6P_RECVDSTADDR);
   1560 					break;
   1561 
   1562 				case IPV6_PORTRANGE:
   1563 				    {
   1564 					int flags;
   1565 					flags = in6p->in6p_flags;
   1566 					if (flags & IN6P_HIGHPORT)
   1567 						optval = IPV6_PORTRANGE_HIGH;
   1568 					else if (flags & IN6P_LOWPORT)
   1569 						optval = IPV6_PORTRANGE_LOW;
   1570 					else
   1571 						optval = 0;
   1572 					break;
   1573 				    }
   1574 
   1575 				case IPV6_PKTINFO:
   1576 					optval = OPTBIT(IN6P_PKTINFO);
   1577 					break;
   1578 
   1579 				case IPV6_HOPLIMIT:
   1580 					optval = OPTBIT(IN6P_HOPLIMIT);
   1581 					break;
   1582 
   1583 				case IPV6_HOPOPTS:
   1584 					optval = OPTBIT(IN6P_HOPOPTS);
   1585 					break;
   1586 
   1587 				case IPV6_DSTOPTS:
   1588 					optval = OPTBIT(IN6P_DSTOPTS);
   1589 					break;
   1590 
   1591 				case IPV6_RTHDR:
   1592 					optval = OPTBIT(IN6P_RTHDR);
   1593 					break;
   1594 
   1595 				case IPV6_FAITH:
   1596 					optval = OPTBIT(IN6P_FAITH);
   1597 					break;
   1598 
   1599 				case IPV6_V6ONLY:
   1600 					optval = OPTBIT(IN6P_IPV6_V6ONLY);
   1601 					break;
   1602 
   1603 				case IPV6_USE_MIN_MTU:
   1604 					optval = OPTBIT(IN6P_MINMTU);
   1605 					break;
   1606 				}
   1607 				*mtod(m, int *) = optval;
   1608 				break;
   1609 
   1610 			case IPV6_MULTICAST_IF:
   1611 			case IPV6_MULTICAST_HOPS:
   1612 			case IPV6_MULTICAST_LOOP:
   1613 			case IPV6_JOIN_GROUP:
   1614 			case IPV6_LEAVE_GROUP:
   1615 				error = ip6_getmoptions(optname, in6p->in6p_moptions, mp);
   1616 				break;
   1617 
   1618 #if 0	/* defined(IPSEC) */
   1619 			/* XXX: code broken */
   1620 			case IPV6_IPSEC_POLICY:
   1621 			{
   1622 				caddr_t req = NULL;
   1623 				size_t len = 0;
   1624 
   1625 				if (m) {
   1626 					req = mtod(m, caddr_t);
   1627 					len = m->m_len;
   1628 				}
   1629 				error = ipsec6_get_policy(in6p, req, len, mp);
   1630 				break;
   1631 			}
   1632 #endif /* IPSEC */
   1633 
   1634 			default:
   1635 				error = ENOPROTOOPT;
   1636 				break;
   1637 			}
   1638 			break;
   1639 		}
   1640 	} else {
   1641 		error = EINVAL;
   1642 		if (op == PRCO_SETOPT && *mp)
   1643 			(void)m_free(*mp);
   1644 	}
   1645 	return (error);
   1646 }
   1647 
   1648 int
   1649 ip6_raw_ctloutput(op, so, level, optname, mp)
   1650 	int op;
   1651 	struct socket *so;
   1652 	int level, optname;
   1653 	struct mbuf **mp;
   1654 {
   1655 	int error = 0, optval, optlen;
   1656 	const int icmp6off = offsetof(struct icmp6_hdr, icmp6_cksum);
   1657 	struct in6pcb *in6p = sotoin6pcb(so);
   1658 	struct mbuf *m = *mp;
   1659 
   1660 	optlen = m ? m->m_len : 0;
   1661 
   1662 	if (level != IPPROTO_IPV6) {
   1663 		if (op == PRCO_SETOPT && *mp)
   1664 			(void)m_free(*mp);
   1665 		return (EINVAL);
   1666 	}
   1667 
   1668 	switch (optname) {
   1669 	case IPV6_CHECKSUM:
   1670 		/*
   1671 		 * For ICMPv6 sockets, no modification allowed for checksum
   1672 		 * offset, permit "no change" values to help existing apps.
   1673 		 *
   1674 		 * XXX 2292bis says: "An attempt to set IPV6_CHECKSUM
   1675 		 * for an ICMPv6 socket will fail."
   1676 		 * The current behavior does not meet 2292bis.
   1677 		 */
   1678 		switch (op) {
   1679 		case PRCO_SETOPT:
   1680 			if (optlen != sizeof(int)) {
   1681 				error = EINVAL;
   1682 				break;
   1683 			}
   1684 			optval = *mtod(m, int *);
   1685 			if ((optval % 2) != 0) {
   1686 				/* the API assumes even offset values */
   1687 				error = EINVAL;
   1688 			} else if (so->so_proto->pr_protocol ==
   1689 			    IPPROTO_ICMPV6) {
   1690 				if (optval != icmp6off)
   1691 					error = EINVAL;
   1692 			} else
   1693 				in6p->in6p_cksum = optval;
   1694 			break;
   1695 
   1696 		case PRCO_GETOPT:
   1697 			if (so->so_proto->pr_protocol == IPPROTO_ICMPV6)
   1698 				optval = icmp6off;
   1699 			else
   1700 				optval = in6p->in6p_cksum;
   1701 
   1702 			*mp = m = m_get(M_WAIT, MT_SOOPTS);
   1703 			m->m_len = sizeof(int);
   1704 			*mtod(m, int *) = optval;
   1705 			break;
   1706 
   1707 		default:
   1708 			error = EINVAL;
   1709 			break;
   1710 		}
   1711 		break;
   1712 
   1713 	default:
   1714 		error = ENOPROTOOPT;
   1715 		break;
   1716 	}
   1717 
   1718 	if (op == PRCO_SETOPT && m)
   1719 		(void)m_free(m);
   1720 
   1721 	return (error);
   1722 }
   1723 
   1724 /*
   1725  * Set up IP6 options in pcb for insertion in output packets.
   1726  * Store in mbuf with pointer in pcbopt, adding pseudo-option
   1727  * with destination address if source routed.
   1728  */
   1729 static int
   1730 ip6_pcbopts(pktopt, m, so)
   1731 	struct ip6_pktopts **pktopt;
   1732 	struct mbuf *m;
   1733 	struct socket *so;
   1734 {
   1735 	struct ip6_pktopts *opt = *pktopt;
   1736 	int error = 0;
   1737 	struct proc *p = curproc;	/* XXX */
   1738 	int priv = 0;
   1739 
   1740 	/* turn off any old options. */
   1741 	if (opt) {
   1742 		if (opt->ip6po_m)
   1743 			(void)m_free(opt->ip6po_m);
   1744 	} else
   1745 		opt = malloc(sizeof(*opt), M_IP6OPT, M_WAITOK);
   1746 	*pktopt = 0;
   1747 
   1748 	if (!m || m->m_len == 0) {
   1749 		/*
   1750 		 * Only turning off any previous options.
   1751 		 */
   1752 		free(opt, M_IP6OPT);
   1753 		if (m)
   1754 			(void)m_free(m);
   1755 		return (0);
   1756 	}
   1757 
   1758 	/*  set options specified by user. */
   1759 	if (p && !suser(p->p_ucred, &p->p_acflag))
   1760 		priv = 1;
   1761 	if ((error = ip6_setpktoptions(m, opt, priv)) != 0) {
   1762 		(void)m_free(m);
   1763 		free(opt, M_IP6OPT);
   1764 		return (error);
   1765 	}
   1766 	*pktopt = opt;
   1767 	return (0);
   1768 }
   1769 
   1770 /*
   1771  * Set the IP6 multicast options in response to user setsockopt().
   1772  */
   1773 static int
   1774 ip6_setmoptions(optname, im6op, m)
   1775 	int optname;
   1776 	struct ip6_moptions **im6op;
   1777 	struct mbuf *m;
   1778 {
   1779 	int error = 0;
   1780 	u_int loop, ifindex;
   1781 	struct ipv6_mreq *mreq;
   1782 	struct ifnet *ifp;
   1783 	struct ip6_moptions *im6o = *im6op;
   1784 	struct route_in6 ro;
   1785 	struct sockaddr_in6 *dst;
   1786 	struct in6_multi_mship *imm;
   1787 	struct proc *p = curproc;	/* XXX */
   1788 
   1789 	if (im6o == NULL) {
   1790 		/*
   1791 		 * No multicast option buffer attached to the pcb;
   1792 		 * allocate one and initialize to default values.
   1793 		 */
   1794 		im6o = (struct ip6_moptions *)
   1795 			malloc(sizeof(*im6o), M_IPMOPTS, M_WAITOK);
   1796 
   1797 		if (im6o == NULL)
   1798 			return (ENOBUFS);
   1799 		*im6op = im6o;
   1800 		im6o->im6o_multicast_ifp = NULL;
   1801 		im6o->im6o_multicast_hlim = ip6_defmcasthlim;
   1802 		im6o->im6o_multicast_loop = IPV6_DEFAULT_MULTICAST_LOOP;
   1803 		LIST_INIT(&im6o->im6o_memberships);
   1804 	}
   1805 
   1806 	switch (optname) {
   1807 
   1808 	case IPV6_MULTICAST_IF:
   1809 		/*
   1810 		 * Select the interface for outgoing multicast packets.
   1811 		 */
   1812 		if (m == NULL || m->m_len != sizeof(u_int)) {
   1813 			error = EINVAL;
   1814 			break;
   1815 		}
   1816 		bcopy(mtod(m, u_int *), &ifindex, sizeof(ifindex));
   1817 		if (ifindex < 0 || if_indexlim <= ifindex ||
   1818 		    !ifindex2ifnet[ifindex]) {
   1819 			error = ENXIO;	/* XXX EINVAL? */
   1820 			break;
   1821 		}
   1822 		ifp = ifindex2ifnet[ifindex];
   1823 		if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
   1824 			error = EADDRNOTAVAIL;
   1825 			break;
   1826 		}
   1827 		im6o->im6o_multicast_ifp = ifp;
   1828 		break;
   1829 
   1830 	case IPV6_MULTICAST_HOPS:
   1831 	    {
   1832 		/*
   1833 		 * Set the IP6 hoplimit for outgoing multicast packets.
   1834 		 */
   1835 		int optval;
   1836 		if (m == NULL || m->m_len != sizeof(int)) {
   1837 			error = EINVAL;
   1838 			break;
   1839 		}
   1840 		bcopy(mtod(m, u_int *), &optval, sizeof(optval));
   1841 		if (optval < -1 || optval >= 256)
   1842 			error = EINVAL;
   1843 		else if (optval == -1)
   1844 			im6o->im6o_multicast_hlim = ip6_defmcasthlim;
   1845 		else
   1846 			im6o->im6o_multicast_hlim = optval;
   1847 		break;
   1848 	    }
   1849 
   1850 	case IPV6_MULTICAST_LOOP:
   1851 		/*
   1852 		 * Set the loopback flag for outgoing multicast packets.
   1853 		 * Must be zero or one.
   1854 		 */
   1855 		if (m == NULL || m->m_len != sizeof(u_int)) {
   1856 			error = EINVAL;
   1857 			break;
   1858 		}
   1859 		bcopy(mtod(m, u_int *), &loop, sizeof(loop));
   1860 		if (loop > 1) {
   1861 			error = EINVAL;
   1862 			break;
   1863 		}
   1864 		im6o->im6o_multicast_loop = loop;
   1865 		break;
   1866 
   1867 	case IPV6_JOIN_GROUP:
   1868 		/*
   1869 		 * Add a multicast group membership.
   1870 		 * Group must be a valid IP6 multicast address.
   1871 		 */
   1872 		if (m == NULL || m->m_len != sizeof(struct ipv6_mreq)) {
   1873 			error = EINVAL;
   1874 			break;
   1875 		}
   1876 		mreq = mtod(m, struct ipv6_mreq *);
   1877 		if (IN6_IS_ADDR_UNSPECIFIED(&mreq->ipv6mr_multiaddr)) {
   1878 			/*
   1879 			 * We use the unspecified address to specify to accept
   1880 			 * all multicast addresses. Only super user is allowed
   1881 			 * to do this.
   1882 			 */
   1883 			if (suser(p->p_ucred, &p->p_acflag))
   1884 			{
   1885 				error = EACCES;
   1886 				break;
   1887 			}
   1888 		} else if (!IN6_IS_ADDR_MULTICAST(&mreq->ipv6mr_multiaddr)) {
   1889 			error = EINVAL;
   1890 			break;
   1891 		}
   1892 
   1893 		/*
   1894 		 * If the interface is specified, validate it.
   1895 		 */
   1896 		if (mreq->ipv6mr_interface < 0 ||
   1897 		    if_indexlim <= mreq->ipv6mr_interface ||
   1898 		    !ifindex2ifnet[mreq->ipv6mr_interface]) {
   1899 			error = ENXIO;	/* XXX EINVAL? */
   1900 			break;
   1901 		}
   1902 		/*
   1903 		 * If no interface was explicitly specified, choose an
   1904 		 * appropriate one according to the given multicast address.
   1905 		 */
   1906 		if (mreq->ipv6mr_interface == 0) {
   1907 			/*
   1908 			 * If the multicast address is in node-local scope,
   1909 			 * the interface should be a loopback interface.
   1910 			 * Otherwise, look up the routing table for the
   1911 			 * address, and choose the outgoing interface.
   1912 			 *   XXX: is it a good approach?
   1913 			 */
   1914 			if (IN6_IS_ADDR_MC_NODELOCAL(&mreq->ipv6mr_multiaddr)) {
   1915 				ifp = &loif[0];
   1916 			} else {
   1917 				ro.ro_rt = NULL;
   1918 				dst = (struct sockaddr_in6 *)&ro.ro_dst;
   1919 				bzero(dst, sizeof(*dst));
   1920 				dst->sin6_len = sizeof(struct sockaddr_in6);
   1921 				dst->sin6_family = AF_INET6;
   1922 				dst->sin6_addr = mreq->ipv6mr_multiaddr;
   1923 				rtalloc((struct route *)&ro);
   1924 				if (ro.ro_rt == NULL) {
   1925 					error = EADDRNOTAVAIL;
   1926 					break;
   1927 				}
   1928 				ifp = ro.ro_rt->rt_ifp;
   1929 				rtfree(ro.ro_rt);
   1930 			}
   1931 		} else
   1932 			ifp = ifindex2ifnet[mreq->ipv6mr_interface];
   1933 
   1934 		/*
   1935 		 * See if we found an interface, and confirm that it
   1936 		 * supports multicast
   1937 		 */
   1938 		if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
   1939 			error = EADDRNOTAVAIL;
   1940 			break;
   1941 		}
   1942 		/*
   1943 		 * Put interface index into the multicast address,
   1944 		 * if the address has link-local scope.
   1945 		 */
   1946 		if (IN6_IS_ADDR_MC_LINKLOCAL(&mreq->ipv6mr_multiaddr)) {
   1947 			mreq->ipv6mr_multiaddr.s6_addr16[1] =
   1948 			    htons(ifp->if_index);
   1949 		}
   1950 		/*
   1951 		 * See if the membership already exists.
   1952 		 */
   1953 		for (imm = im6o->im6o_memberships.lh_first;
   1954 		     imm != NULL; imm = imm->i6mm_chain.le_next)
   1955 			if (imm->i6mm_maddr->in6m_ifp == ifp &&
   1956 			    IN6_ARE_ADDR_EQUAL(&imm->i6mm_maddr->in6m_addr,
   1957 			    &mreq->ipv6mr_multiaddr))
   1958 				break;
   1959 		if (imm != NULL) {
   1960 			error = EADDRINUSE;
   1961 			break;
   1962 		}
   1963 		/*
   1964 		 * Everything looks good; add a new record to the multicast
   1965 		 * address list for the given interface.
   1966 		 */
   1967 		imm = in6_joingroup(ifp, &mreq->ipv6mr_multiaddr, &error);
   1968 		if (!imm)
   1969 			break;
   1970 		LIST_INSERT_HEAD(&im6o->im6o_memberships, imm, i6mm_chain);
   1971 		break;
   1972 
   1973 	case IPV6_LEAVE_GROUP:
   1974 		/*
   1975 		 * Drop a multicast group membership.
   1976 		 * Group must be a valid IP6 multicast address.
   1977 		 */
   1978 		if (m == NULL || m->m_len != sizeof(struct ipv6_mreq)) {
   1979 			error = EINVAL;
   1980 			break;
   1981 		}
   1982 		mreq = mtod(m, struct ipv6_mreq *);
   1983 		if (IN6_IS_ADDR_UNSPECIFIED(&mreq->ipv6mr_multiaddr)) {
   1984 			if (suser(p->p_ucred, &p->p_acflag))
   1985 			{
   1986 				error = EACCES;
   1987 				break;
   1988 			}
   1989 		} else if (!IN6_IS_ADDR_MULTICAST(&mreq->ipv6mr_multiaddr)) {
   1990 			error = EINVAL;
   1991 			break;
   1992 		}
   1993 		/*
   1994 		 * If an interface address was specified, get a pointer
   1995 		 * to its ifnet structure.
   1996 		 */
   1997 		if (mreq->ipv6mr_interface < 0 ||
   1998 		    if_indexlim <= mreq->ipv6mr_interface ||
   1999 		    !ifindex2ifnet[mreq->ipv6mr_interface]) {
   2000 			error = ENXIO;	/* XXX EINVAL? */
   2001 			break;
   2002 		}
   2003 		ifp = ifindex2ifnet[mreq->ipv6mr_interface];
   2004 		/*
   2005 		 * Put interface index into the multicast address,
   2006 		 * if the address has link-local scope.
   2007 		 */
   2008 		if (IN6_IS_ADDR_MC_LINKLOCAL(&mreq->ipv6mr_multiaddr)) {
   2009 			mreq->ipv6mr_multiaddr.s6_addr16[1] =
   2010 			    htons(mreq->ipv6mr_interface);
   2011 		}
   2012 		/*
   2013 		 * Find the membership in the membership list.
   2014 		 */
   2015 		for (imm = im6o->im6o_memberships.lh_first;
   2016 		     imm != NULL; imm = imm->i6mm_chain.le_next) {
   2017 			if ((ifp == NULL || imm->i6mm_maddr->in6m_ifp == ifp) &&
   2018 			    IN6_ARE_ADDR_EQUAL(&imm->i6mm_maddr->in6m_addr,
   2019 			    &mreq->ipv6mr_multiaddr))
   2020 				break;
   2021 		}
   2022 		if (imm == NULL) {
   2023 			/* Unable to resolve interface */
   2024 			error = EADDRNOTAVAIL;
   2025 			break;
   2026 		}
   2027 		/*
   2028 		 * Give up the multicast address record to which the
   2029 		 * membership points.
   2030 		 */
   2031 		LIST_REMOVE(imm, i6mm_chain);
   2032 		in6_leavegroup(imm);
   2033 		break;
   2034 
   2035 	default:
   2036 		error = EOPNOTSUPP;
   2037 		break;
   2038 	}
   2039 
   2040 	/*
   2041 	 * If all options have default values, no need to keep the mbuf.
   2042 	 */
   2043 	if (im6o->im6o_multicast_ifp == NULL &&
   2044 	    im6o->im6o_multicast_hlim == ip6_defmcasthlim &&
   2045 	    im6o->im6o_multicast_loop == IPV6_DEFAULT_MULTICAST_LOOP &&
   2046 	    im6o->im6o_memberships.lh_first == NULL) {
   2047 		free(*im6op, M_IPMOPTS);
   2048 		*im6op = NULL;
   2049 	}
   2050 
   2051 	return (error);
   2052 }
   2053 
   2054 /*
   2055  * Return the IP6 multicast options in response to user getsockopt().
   2056  */
   2057 static int
   2058 ip6_getmoptions(optname, im6o, mp)
   2059 	int optname;
   2060 	struct ip6_moptions *im6o;
   2061 	struct mbuf **mp;
   2062 {
   2063 	u_int *hlim, *loop, *ifindex;
   2064 
   2065 	*mp = m_get(M_WAIT, MT_SOOPTS);
   2066 
   2067 	switch (optname) {
   2068 
   2069 	case IPV6_MULTICAST_IF:
   2070 		ifindex = mtod(*mp, u_int *);
   2071 		(*mp)->m_len = sizeof(u_int);
   2072 		if (im6o == NULL || im6o->im6o_multicast_ifp == NULL)
   2073 			*ifindex = 0;
   2074 		else
   2075 			*ifindex = im6o->im6o_multicast_ifp->if_index;
   2076 		return (0);
   2077 
   2078 	case IPV6_MULTICAST_HOPS:
   2079 		hlim = mtod(*mp, u_int *);
   2080 		(*mp)->m_len = sizeof(u_int);
   2081 		if (im6o == NULL)
   2082 			*hlim = ip6_defmcasthlim;
   2083 		else
   2084 			*hlim = im6o->im6o_multicast_hlim;
   2085 		return (0);
   2086 
   2087 	case IPV6_MULTICAST_LOOP:
   2088 		loop = mtod(*mp, u_int *);
   2089 		(*mp)->m_len = sizeof(u_int);
   2090 		if (im6o == NULL)
   2091 			*loop = ip6_defmcasthlim;
   2092 		else
   2093 			*loop = im6o->im6o_multicast_loop;
   2094 		return (0);
   2095 
   2096 	default:
   2097 		return (EOPNOTSUPP);
   2098 	}
   2099 }
   2100 
   2101 /*
   2102  * Discard the IP6 multicast options.
   2103  */
   2104 void
   2105 ip6_freemoptions(im6o)
   2106 	struct ip6_moptions *im6o;
   2107 {
   2108 	struct in6_multi_mship *imm;
   2109 
   2110 	if (im6o == NULL)
   2111 		return;
   2112 
   2113 	while ((imm = im6o->im6o_memberships.lh_first) != NULL) {
   2114 		LIST_REMOVE(imm, i6mm_chain);
   2115 		in6_leavegroup(imm);
   2116 	}
   2117 	free(im6o, M_IPMOPTS);
   2118 }
   2119 
   2120 /*
   2121  * Set IPv6 outgoing packet options based on advanced API.
   2122  */
   2123 int
   2124 ip6_setpktoptions(control, opt, priv)
   2125 	struct mbuf *control;
   2126 	struct ip6_pktopts *opt;
   2127 	int priv;
   2128 {
   2129 	struct cmsghdr *cm = 0;
   2130 
   2131 	if (control == 0 || opt == 0)
   2132 		return (EINVAL);
   2133 
   2134 	bzero(opt, sizeof(*opt));
   2135 	opt->ip6po_hlim = -1; /* -1 means to use default hop limit */
   2136 
   2137 	/*
   2138 	 * XXX: Currently, we assume all the optional information is stored
   2139 	 * in a single mbuf.
   2140 	 */
   2141 	if (control->m_next)
   2142 		return (EINVAL);
   2143 
   2144 	opt->ip6po_m = control;
   2145 
   2146 	for (; control->m_len; control->m_data += CMSG_ALIGN(cm->cmsg_len),
   2147 	    control->m_len -= CMSG_ALIGN(cm->cmsg_len)) {
   2148 		cm = mtod(control, struct cmsghdr *);
   2149 		if (cm->cmsg_len == 0 || cm->cmsg_len > control->m_len)
   2150 			return (EINVAL);
   2151 		if (cm->cmsg_level != IPPROTO_IPV6)
   2152 			continue;
   2153 
   2154 		switch (cm->cmsg_type) {
   2155 		case IPV6_PKTINFO:
   2156 			if (cm->cmsg_len != CMSG_LEN(sizeof(struct in6_pktinfo)))
   2157 				return (EINVAL);
   2158 			opt->ip6po_pktinfo = (struct in6_pktinfo *)CMSG_DATA(cm);
   2159 			if (opt->ip6po_pktinfo->ipi6_ifindex &&
   2160 			    IN6_IS_ADDR_LINKLOCAL(&opt->ip6po_pktinfo->ipi6_addr))
   2161 				opt->ip6po_pktinfo->ipi6_addr.s6_addr16[1] =
   2162 					htons(opt->ip6po_pktinfo->ipi6_ifindex);
   2163 
   2164 			if (opt->ip6po_pktinfo->ipi6_ifindex >= if_indexlim ||
   2165 			    opt->ip6po_pktinfo->ipi6_ifindex < 0)
   2166 				return (ENXIO);
   2167 			if (opt->ip6po_pktinfo->ipi6_ifindex > 0 &&
   2168 			    !ifindex2ifnet[opt->ip6po_pktinfo->ipi6_ifindex])
   2169 				return (ENXIO);
   2170 
   2171 			/*
   2172 			 * Check if the requested source address is indeed a
   2173 			 * unicast address assigned to the node, and can be
   2174 			 * used as the packet's source address.
   2175 			 */
   2176 			if (!IN6_IS_ADDR_UNSPECIFIED(&opt->ip6po_pktinfo->ipi6_addr)) {
   2177 				struct ifaddr *ia;
   2178 				struct in6_ifaddr *ia6;
   2179 				struct sockaddr_in6 sin6;
   2180 
   2181 				bzero(&sin6, sizeof(sin6));
   2182 				sin6.sin6_len = sizeof(sin6);
   2183 				sin6.sin6_family = AF_INET6;
   2184 				sin6.sin6_addr =
   2185 					opt->ip6po_pktinfo->ipi6_addr;
   2186 				ia = ifa_ifwithaddr(sin6tosa(&sin6));
   2187 				if (ia == NULL ||
   2188 				    (opt->ip6po_pktinfo->ipi6_ifindex &&
   2189 				     (ia->ifa_ifp->if_index !=
   2190 				      opt->ip6po_pktinfo->ipi6_ifindex))) {
   2191 					return (EADDRNOTAVAIL);
   2192 				}
   2193 				ia6 = (struct in6_ifaddr *)ia;
   2194 				if ((ia6->ia6_flags & (IN6_IFF_ANYCAST|IN6_IFF_NOTREADY)) != 0) {
   2195 					return (EADDRNOTAVAIL);
   2196 				}
   2197 
   2198 				/*
   2199 				 * Check if the requested source address is
   2200 				 * indeed a unicast address assigned to the
   2201 				 * node.
   2202 				 */
   2203 				if (IN6_IS_ADDR_MULTICAST(&opt->ip6po_pktinfo->ipi6_addr))
   2204 					return (EADDRNOTAVAIL);
   2205 			}
   2206 			break;
   2207 
   2208 		case IPV6_HOPLIMIT:
   2209 			if (cm->cmsg_len != CMSG_LEN(sizeof(int)))
   2210 				return (EINVAL);
   2211 			else {
   2212 				int t;
   2213 
   2214 				bcopy(CMSG_DATA(cm), &t, sizeof(t));
   2215 				if (t < -1 || t > 255)
   2216 					return (EINVAL);
   2217 				opt->ip6po_hlim = t;
   2218 			}
   2219 			break;
   2220 
   2221 		case IPV6_NEXTHOP:
   2222 			if (!priv)
   2223 				return (EPERM);
   2224 
   2225 			/* check if cmsg_len is large enough for sa_len */
   2226 			if (cm->cmsg_len < sizeof(u_char) ||
   2227 			    cm->cmsg_len < CMSG_LEN(*CMSG_DATA(cm)))
   2228 				return (EINVAL);
   2229 
   2230 			opt->ip6po_nexthop = (struct sockaddr *)CMSG_DATA(cm);
   2231 
   2232 			break;
   2233 
   2234 		case IPV6_HOPOPTS:
   2235 			if (cm->cmsg_len < CMSG_LEN(sizeof(struct ip6_hbh)))
   2236 				return (EINVAL);
   2237 			else {
   2238 				struct  ip6_hbh *t;
   2239 
   2240 				t = (struct ip6_hbh *)CMSG_DATA(cm);
   2241 				if (cm->cmsg_len !=
   2242 				    CMSG_LEN((t->ip6h_len + 1) << 3))
   2243 					return (EINVAL);
   2244 				opt->ip6po_hbh = t;
   2245 			}
   2246 			break;
   2247 
   2248 		case IPV6_DSTOPTS:
   2249 			if (cm->cmsg_len < CMSG_LEN(sizeof(struct ip6_dest)))
   2250 				return (EINVAL);
   2251 
   2252 			/*
   2253 			 * If there is no routing header yet, the destination
   2254 			 * options header should be put on the 1st part.
   2255 			 * Otherwise, the header should be on the 2nd part.
   2256 			 * (See RFC 2460, section 4.1)
   2257 			 */
   2258 			if (opt->ip6po_rthdr == NULL) {
   2259 				struct ip6_dest *t;
   2260 
   2261 				t = (struct ip6_dest *)CMSG_DATA(cm);
   2262 				if (cm->cmsg_len !=
   2263 				    CMSG_LEN((t->ip6d_len + 1) << 3));
   2264 					return (EINVAL);
   2265 				opt->ip6po_dest1 = t;
   2266 			}
   2267 			else {
   2268 				struct ip6_dest *t;
   2269 
   2270 				t = (struct ip6_dest *)CMSG_DATA(cm);
   2271 				if (cm->cmsg_len !=
   2272 				    CMSG_LEN((opt->ip6po_dest2->ip6d_len + 1) << 3))
   2273 					return (EINVAL);
   2274 				opt->ip6po_dest2 = t;
   2275 			}
   2276 			break;
   2277 
   2278 		case IPV6_RTHDR:
   2279 			if (cm->cmsg_len < CMSG_LEN(sizeof(struct ip6_rthdr)))
   2280 				return (EINVAL);
   2281 			else {
   2282 				struct ip6_rthdr *t;
   2283 
   2284 				t = (struct ip6_rthdr *)CMSG_DATA(cm);
   2285 				if (cm->cmsg_len !=
   2286 				    CMSG_LEN((t->ip6r_len + 1) << 3))
   2287 					return (EINVAL);
   2288 				switch (t->ip6r_type) {
   2289 				case IPV6_RTHDR_TYPE_0:
   2290 					if (t->ip6r_segleft == 0)
   2291 						return (EINVAL);
   2292 					break;
   2293 				default:
   2294 					return (EINVAL);
   2295 				}
   2296 				opt->ip6po_rthdr = t;
   2297 			}
   2298 			break;
   2299 
   2300 		default:
   2301 			return (ENOPROTOOPT);
   2302 		}
   2303 	}
   2304 
   2305 	return (0);
   2306 }
   2307 
   2308 /*
   2309  * Routine called from ip6_output() to loop back a copy of an IP6 multicast
   2310  * packet to the input queue of a specified interface.  Note that this
   2311  * calls the output routine of the loopback "driver", but with an interface
   2312  * pointer that might NOT be &loif -- easier than replicating that code here.
   2313  */
   2314 void
   2315 ip6_mloopback(ifp, m, dst)
   2316 	struct ifnet *ifp;
   2317 	struct mbuf *m;
   2318 	struct sockaddr_in6 *dst;
   2319 {
   2320 	struct mbuf *copym;
   2321 	struct ip6_hdr *ip6;
   2322 
   2323 	copym = m_copy(m, 0, M_COPYALL);
   2324 	if (copym == NULL)
   2325 		return;
   2326 
   2327 	/*
   2328 	 * Make sure to deep-copy IPv6 header portion in case the data
   2329 	 * is in an mbuf cluster, so that we can safely override the IPv6
   2330 	 * header portion later.
   2331 	 */
   2332 	if ((copym->m_flags & M_EXT) != 0 ||
   2333 	    copym->m_len < sizeof(struct ip6_hdr)) {
   2334 		copym = m_pullup(copym, sizeof(struct ip6_hdr));
   2335 		if (copym == NULL)
   2336 			return;
   2337 	}
   2338 
   2339 #ifdef DIAGNOSTIC
   2340 	if (copym->m_len < sizeof(*ip6)) {
   2341 		m_freem(copym);
   2342 		return;
   2343 	}
   2344 #endif
   2345 
   2346 	ip6 = mtod(copym, struct ip6_hdr *);
   2347 	if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
   2348 		ip6->ip6_src.s6_addr16[1] = 0;
   2349 	if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
   2350 		ip6->ip6_dst.s6_addr16[1] = 0;
   2351 
   2352 	(void)looutput(ifp, copym, (struct sockaddr *)dst, NULL);
   2353 }
   2354 
   2355 /*
   2356  * Chop IPv6 header off from the payload.
   2357  */
   2358 static int
   2359 ip6_splithdr(m, exthdrs)
   2360 	struct mbuf *m;
   2361 	struct ip6_exthdrs *exthdrs;
   2362 {
   2363 	struct mbuf *mh;
   2364 	struct ip6_hdr *ip6;
   2365 
   2366 	ip6 = mtod(m, struct ip6_hdr *);
   2367 	if (m->m_len > sizeof(*ip6)) {
   2368 		MGETHDR(mh, M_DONTWAIT, MT_HEADER);
   2369 		if (mh == 0) {
   2370 			m_freem(m);
   2371 			return ENOBUFS;
   2372 		}
   2373 		M_COPY_PKTHDR(mh, m);
   2374 		MH_ALIGN(mh, sizeof(*ip6));
   2375 		m_tag_delete_chain(m, NULL);
   2376 		m->m_flags &= ~M_PKTHDR;
   2377 		m->m_len -= sizeof(*ip6);
   2378 		m->m_data += sizeof(*ip6);
   2379 		mh->m_next = m;
   2380 		m = mh;
   2381 		m->m_len = sizeof(*ip6);
   2382 		bcopy((caddr_t)ip6, mtod(m, caddr_t), sizeof(*ip6));
   2383 	}
   2384 	exthdrs->ip6e_ip6 = m;
   2385 	return 0;
   2386 }
   2387 
   2388 /*
   2389  * Compute IPv6 extension header length.
   2390  */
   2391 int
   2392 ip6_optlen(in6p)
   2393 	struct in6pcb *in6p;
   2394 {
   2395 	int len;
   2396 
   2397 	if (!in6p->in6p_outputopts)
   2398 		return 0;
   2399 
   2400 	len = 0;
   2401 #define elen(x) \
   2402     (((struct ip6_ext *)(x)) ? (((struct ip6_ext *)(x))->ip6e_len + 1) << 3 : 0)
   2403 
   2404 	len += elen(in6p->in6p_outputopts->ip6po_hbh);
   2405 	len += elen(in6p->in6p_outputopts->ip6po_dest1);
   2406 	len += elen(in6p->in6p_outputopts->ip6po_rthdr);
   2407 	len += elen(in6p->in6p_outputopts->ip6po_dest2);
   2408 	return len;
   2409 #undef elen
   2410 }
   2411