/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      $KAME: ip6_output.c,v 1.279 2002/01/26 06:12:30 jinmei Exp $
 */

/*-
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ipsec.h"
#include "opt_kern_tls.h"
#include "opt_ratelimit.h"
#include "opt_rss.h"
#include "opt_sctp.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/ktls.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/syslog.h>
#include <sys/ucred.h>

#include <machine/in_cksum.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_vlan_var.h>
#include <net/if_llatbl.h>
#include <net/ethernet.h>
#include <net/netisr.h>
#include <net/route.h>
#include <net/route/nhop.h>
#include <net/pfil.h>
#include <net/rss_config.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet6/in6_fib.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet6/ip6_var.h>
#include <netinet/in_pcb.h>
#include <netinet/tcp_var.h>
#include <netinet6/nd6.h>
#include <netinet6/in6_rss.h>
#include <netinet6/ip6_mroute.h>

#include <netipsec/ipsec_support.h>
#if defined(SCTP) || defined(SCTP_SUPPORT)
#include <netinet/sctp.h>
#include <netinet/sctp_crc32.h>
#endif

#include <netinet6/scope6_var.h>

extern int in6_mcast_loop;

struct ip6_exthdrs {
        struct mbuf *ip6e_ip6;
        struct mbuf *ip6e_hbh;
        struct mbuf *ip6e_dest1;
        struct mbuf *ip6e_rthdr;
        struct mbuf *ip6e_dest2;
};

static MALLOC_DEFINE(M_IP6OPT, "ip6opt", "IPv6 options");

static int ip6_pcbopt(int, u_char *, int, struct ip6_pktopts **,
                           struct ucred *, int);
static int ip6_pcbopts(struct ip6_pktopts **, struct mbuf *,
        struct socket *, struct sockopt *);
static int ip6_getpcbopt(struct inpcb *, int, struct sockopt *);
static int ip6_setpktopt(int, u_char *, int, struct ip6_pktopts *,
        struct ucred *, int, int, int);

static int ip6_copyexthdr(struct mbuf **, caddr_t, int);
static int ip6_insertfraghdr(struct mbuf *, struct mbuf *, int,
        struct ip6_frag **);
static int ip6_splithdr(struct mbuf *, struct ip6_exthdrs *);
static void ip6_getpmtu(struct route_in6 *, int,
        struct ifnet *, const struct in6_addr *, u_long *, u_int, u_int);
static void ip6_calcmtu(struct ifnet *, const struct in6_addr *, u_long,
        u_long *, u_int);
static int ip6_getpmtu_ctl(u_int, const struct in6_addr *, u_long *);
static int copypktopts(struct ip6_pktopts *, struct ip6_pktopts *, int);

/*
 * Make an extension header from option data.  hp is the source,
 * mp is the destination, and _ol is the optlen.
 */
#define MAKE_EXTHDR(hp, mp, _ol)                                        \
    do {                                                                \
        struct ip6_ext *eh = (struct ip6_ext *)(hp);            \
        error = ip6_copyexthdr((mp), (caddr_t)(hp),             \
            ((eh)->ip6e_len + 1) << 3);                         \
        if (error)                                              \
                goto freehdrs;                                  \
        (_ol) += (*(mp))->m_len;                                \
    } while (/*CONSTCOND*/ 0)

/*
 * Form a chain of extension headers.
 * m is the extension header mbuf
 * mp is the previous mbuf in the chain
 * p is the next header
 * i is the type of option.
 */
#define MAKE_CHAIN(m, mp, p, i)\
    do {\
        if (m) {\
                if (!hdrsplit) \
                        panic("%s:%d: assumption failed: "\
                            "hdr not split: hdrsplit %d exthdrs %p",\
                            __func__, __LINE__, hdrsplit, &exthdrs);\
                *mtod((m), u_char *) = *(p);\
                *(p) = (i);\
                p = mtod((m), u_char *);\
                (m)->m_next = (mp)->m_next;\
                (mp)->m_next = (m);\
                (mp) = (m);\
        }\
    } while (/*CONSTCOND*/ 0)

void
in6_delayed_cksum(struct mbuf *m, uint32_t plen, u_short offset)
{
        u_short csum;

        csum = in_cksum_skip(m, offset + plen, offset);
        if (m->m_pkthdr.csum_flags & CSUM_UDP_IPV6 && csum == 0)
                csum = 0xffff;
        offset += m->m_pkthdr.csum_data;        /* checksum offset */

        if (offset + sizeof(csum) > m->m_len)
                m_copyback(m, offset, sizeof(csum), (caddr_t)&csum);
        else
                *(u_short *)mtodo(m, offset) = csum;
}

static void
ip6_output_delayed_csum(struct mbuf *m, struct ifnet *ifp, int csum_flags,
    int plen, int optlen)
{

        KASSERT((plen >= optlen), ("%s:%d: plen %d < optlen %d, m %p, ifp %p "
            "csum_flags %#x",
            __func__, __LINE__, plen, optlen, m, ifp, csum_flags));

        if (csum_flags & CSUM_DELAY_DATA_IPV6) {
                in6_delayed_cksum(m, plen - optlen,
                    sizeof(struct ip6_hdr) + optlen);
                m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
        }
#if defined(SCTP) || defined(SCTP_SUPPORT)
        if (csum_flags & CSUM_SCTP_IPV6) {
                sctp_delayed_cksum(m, sizeof(struct ip6_hdr) + optlen);
                m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
        }
#endif
}

int
ip6_fragment(struct ifnet *ifp, struct mbuf *m0, int hlen, u_char nextproto,
    int fraglen , uint32_t id)
{
        struct mbuf *m, **mnext, *m_frgpart;
        struct ip6_hdr *ip6, *mhip6;
        struct ip6_frag *ip6f;
        int off;
        int error;
        int tlen = m0->m_pkthdr.len;

        KASSERT((fraglen % 8 == 0), ("Fragment length must be a multiple of 8"));

        m = m0;
        ip6 = mtod(m, struct ip6_hdr *);
        mnext = &m->m_nextpkt;

        for (off = hlen; off < tlen; off += fraglen) {
                m = m_gethdr(M_NOWAIT, MT_DATA);
                if (!m) {
                        IP6STAT_INC(ip6s_odropped);
                        return (ENOBUFS);
                }

                /*
                 * Make sure the complete packet header gets copied
                 * from the originating mbuf to the newly created
                 * mbuf. This also ensures that existing firewall
                 * classification(s), VLAN tags and so on get copied
                 * to the resulting fragmented packet(s):
                 */
                if (m_dup_pkthdr(m, m0, M_NOWAIT) == 0) {
                        m_free(m);
                        IP6STAT_INC(ip6s_odropped);
                        return (ENOBUFS);
                }

                *mnext = m;
                mnext = &m->m_nextpkt;
                m->m_data += max_linkhdr;
                mhip6 = mtod(m, struct ip6_hdr *);
                *mhip6 = *ip6;
                m->m_len = sizeof(*mhip6);
                error = ip6_insertfraghdr(m0, m, hlen, &ip6f);
                if (error) {
                        IP6STAT_INC(ip6s_odropped);
                        return (error);
                }
                ip6f->ip6f_offlg = htons((u_short)((off - hlen) & ~7));
                if (off + fraglen >= tlen)
                        fraglen = tlen - off;
                else
                        ip6f->ip6f_offlg |= IP6F_MORE_FRAG;
                mhip6->ip6_plen = htons((u_short)(fraglen + hlen +
                    sizeof(*ip6f) - sizeof(struct ip6_hdr)));
                if ((m_frgpart = m_copym(m0, off, fraglen, M_NOWAIT)) == NULL) {
                        IP6STAT_INC(ip6s_odropped);
                        return (ENOBUFS);
                }
                m_cat(m, m_frgpart);
                m->m_pkthdr.len = fraglen + hlen + sizeof(*ip6f);
                ip6f->ip6f_reserved = 0;
                ip6f->ip6f_ident = id;
                ip6f->ip6f_nxt = nextproto;
                IP6STAT_INC(ip6s_ofragments);
                in6_ifstat_inc(ifp, ifs6_out_fragcreat);
        }

        return (0);
}

static int
ip6_output_send(struct inpcb *inp, struct ifnet *ifp, struct ifnet *origifp,
    struct mbuf *m, struct sockaddr_in6 *dst, struct route_in6 *ro,
    bool stamp_tag)
{
#ifdef KERN_TLS
        struct ktls_session *tls = NULL;
#endif
        struct m_snd_tag *mst;
        int error;

        MPASS((m->m_pkthdr.csum_flags & CSUM_SND_TAG) == 0);
        mst = NULL;

#ifdef KERN_TLS
        /*
         * If this is an unencrypted TLS record, save a reference to
         * the record.  This local reference is used to call
         * ktls_output_eagain after the mbuf has been freed (thus
         * dropping the mbuf's reference) in if_output.
         */
        if (m->m_next != NULL && mbuf_has_tls_session(m->m_next)) {
                tls = ktls_hold(m->m_next->m_epg_tls);
                mst = tls->snd_tag;

                /*
                 * If a TLS session doesn't have a valid tag, it must
                 * have had an earlier ifp mismatch, so drop this
                 * packet.
                 */
                if (mst == NULL) {
                        m_freem(m);
                        error = EAGAIN;
                        goto done;
                }
                /*
                 * Always stamp tags that include NIC ktls.
                 */
                stamp_tag = true;
        }
#endif
#ifdef RATELIMIT
        if (inp != NULL && mst == NULL) {
                if ((inp->inp_flags2 & INP_RATE_LIMIT_CHANGED) != 0 ||
                    (inp->inp_snd_tag != NULL &&
                    inp->inp_snd_tag->ifp != ifp))
                        in_pcboutput_txrtlmt(inp, ifp, m);

                if (inp->inp_snd_tag != NULL)
                        mst = inp->inp_snd_tag;
        }
#endif
        if (stamp_tag && mst != NULL) {
                KASSERT(m->m_pkthdr.rcvif == NULL,
                    ("trying to add a send tag to a forwarded packet"));
                if (mst->ifp != ifp) {
                        m_freem(m);
                        error = EAGAIN;
                        goto done;
                }

                /* stamp send tag on mbuf */
                m->m_pkthdr.snd_tag = m_snd_tag_ref(mst);
                m->m_pkthdr.csum_flags |= CSUM_SND_TAG;
        }

        error = nd6_output_ifp(ifp, origifp, m, dst, (struct route *)ro);

done:
        /* Check for route change invalidating send tags. */
#ifdef KERN_TLS
        if (tls != NULL) {
                if (error == EAGAIN)
                        error = ktls_output_eagain(inp, tls);
                ktls_free(tls);
        }
#endif
#ifdef RATELIMIT
        if (error == EAGAIN)
                in_pcboutput_eagain(inp);
#endif
        return (error);
}

/*
 * IP6 output.
 * The packet in mbuf chain m contains a skeletal IP6 header (with pri, len,
 * nxt, hlim, src, dst).
 * This function may modify ver and hlim only.
 * The mbuf chain containing the packet will be freed.
 * The mbuf opt, if present, will not be freed.
 * If route_in6 ro is present and has ro_nh initialized, route lookup would be
 * skipped and ro->ro_nh would be used. If ro is present but ro->ro_nh is NULL,
 * then result of route lookup is stored in ro->ro_nh.
 *
 * Type of "mtu": rt_mtu is u_long, ifnet.ifr_mtu is int, and nd_ifinfo.linkmtu
 * is uint32_t.  So we use u_long to hold largest one, which is rt_mtu.
 *
 * ifpp - XXX: just for statistics
 */
int
ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
    struct route_in6 *ro, int flags, struct ip6_moptions *im6o,
    struct ifnet **ifpp, struct inpcb *inp)
{
        struct ip6_hdr *ip6;
        struct ifnet *ifp, *origifp;
        struct mbuf *m = m0;
        struct mbuf *mprev;
        struct route_in6 *ro_pmtu;
        struct nhop_object *nh;
        struct sockaddr_in6 *dst, sin6, src_sa, dst_sa;
        struct in6_addr odst;
        u_char *nexthdrp;
        int tlen, len;
        int error = 0;
        int vlan_pcp = -1;
        struct in6_ifaddr *ia = NULL;
        u_long mtu;
        int dontfrag;
        u_int32_t optlen, plen = 0, unfragpartlen;
        struct ip6_exthdrs exthdrs;
        struct in6_addr src0, dst0;
        u_int32_t zone;
        bool hdrsplit;
        int sw_csum, tso;
        int needfiblookup;
        uint32_t fibnum;
        struct m_tag *fwd_tag = NULL;
        uint32_t id;
        uint32_t optvalid;

        NET_EPOCH_ASSERT();

        if (inp != NULL) {
                INP_LOCK_ASSERT(inp);
                M_SETFIB(m, inp->inp_inc.inc_fibnum);
                if ((flags & IP_NODEFAULTFLOWID) == 0) {
                        /* Unconditionally set flowid. */
                        m->m_pkthdr.flowid = inp->inp_flowid;
                        M_HASHTYPE_SET(m, inp->inp_flowtype);
                }
                if ((inp->inp_flags2 & INP_2PCP_SET) != 0)
                        vlan_pcp = (inp->inp_flags2 & INP_2PCP_MASK) >>
                            INP_2PCP_SHIFT;
#ifdef NUMA
                m->m_pkthdr.numa_domain = inp->inp_numa_domain;
#endif
        }

        /* Source address validation. */
        ip6 = mtod(m, struct ip6_hdr *);
        if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) &&
            (flags & IPV6_UNSPECSRC) == 0) {
                error = EOPNOTSUPP;
                IP6STAT_INC(ip6s_badscope);
                goto bad;
        }
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) {
                error = EOPNOTSUPP;
                IP6STAT_INC(ip6s_badscope);
                goto bad;
        }

        /*
         * If we are given packet options to add extension headers prepare them.
         * Calculate the total length of the extension header chain.
         * Keep the length of the unfragmentable part for fragmentation.
         */
        bzero(&exthdrs, sizeof(exthdrs));
        optlen = optvalid = 0;
        unfragpartlen = sizeof(struct ip6_hdr);
        if (opt) {
                optvalid = opt->ip6po_valid;

                /* Hop-by-Hop options header. */
                if ((optvalid & IP6PO_VALID_HBH) != 0)
                        MAKE_EXTHDR(opt->ip6po_hbh, &exthdrs.ip6e_hbh, optlen);

                /* Destination options header (1st part). */
                if ((optvalid & IP6PO_VALID_RHINFO) != 0) {
#ifndef RTHDR_SUPPORT_IMPLEMENTED
                        /*
                         * If there is a routing header, discard the packet
                         * right away here. RH0/1 are obsolete and we do not
                         * currently support RH2/3/4.
                         * People trying to use RH253/254 may want to disable
                         * this check.
                         * The moment we do support any routing header (again)
                         * this block should check the routing type more
                         * selectively.
                         */
                        error = EINVAL;
                        goto bad;
#endif

                        /*
                         * Destination options header (1st part).
                         * This only makes sense with a routing header.
                         * See Section 9.2 of RFC 3542.
                         * Disabling this part just for MIP6 convenience is
                         * a bad idea.  We need to think carefully about a
                         * way to make the advanced API coexist with MIP6
                         * options, which might automatically be inserted in
                         * the kernel.
                         */
                        if ((optvalid & IP6PO_VALID_DEST1) != 0)
                                MAKE_EXTHDR(opt->ip6po_dest1, &exthdrs.ip6e_dest1,
                                    optlen);
                }
                /* Routing header. */
                if ((optvalid & IP6PO_VALID_RHINFO) != 0)
                        MAKE_EXTHDR(opt->ip6po_rthdr, &exthdrs.ip6e_rthdr, optlen);

                unfragpartlen += optlen;

                /*
                 * NOTE: we don't add AH/ESP length here (done in
                 * ip6_ipsec_output()).
                 */

                /* Destination options header (2nd part). */
                if ((optvalid & IP6PO_VALID_DEST2) != 0)
                        MAKE_EXTHDR(opt->ip6po_dest2, &exthdrs.ip6e_dest2, optlen);
        }

        /*
         * If there is at least one extension header,
         * separate IP6 header from the payload.
         */
        hdrsplit = false;
        if (optlen) {
                if ((error = ip6_splithdr(m, &exthdrs)) != 0) {
                        m = NULL;
                        goto freehdrs;
                }
                m = exthdrs.ip6e_ip6;
                ip6 = mtod(m, struct ip6_hdr *);
                hdrsplit = true;
        }

        /* Adjust mbuf packet header length. */
        m->m_pkthdr.len += optlen;
        plen = m->m_pkthdr.len - sizeof(*ip6);

        if (plen > IPV6_MAXPACKET) {
                error = EMSGSIZE;
                goto freehdrs;
        } else
                ip6->ip6_plen = htons(plen);
        nexthdrp = &ip6->ip6_nxt;

        if (optlen) {
                /*
                 * Concatenate headers and fill in next header fields.
                 * Here we have, on "m"
                 *      IPv6 payload
                 * and we insert headers accordingly.
                 * Finally, we should be getting:
                 *      IPv6 hbh dest1 rthdr ah* [esp* dest2 payload].
                 *
                 * During the header composing process "m" points to IPv6
                 * header.  "mprev" points to an extension header prior to esp.
                 */
                mprev = m;

                /*
                 * We treat dest2 specially.  This makes IPsec processing
                 * much easier.  The goal here is to make mprev point the
                 * mbuf prior to dest2.
                 *
                 * Result: IPv6 dest2 payload.
                 * m and mprev will point to IPv6 header.
                 */
                if (exthdrs.ip6e_dest2) {
                        if (!hdrsplit)
                                panic("%s:%d: assumption failed: "
                                    "hdr not split: hdrsplit %d exthdrs %p",
                                    __func__, __LINE__, hdrsplit, &exthdrs);
                        exthdrs.ip6e_dest2->m_next = m->m_next;
                        m->m_next = exthdrs.ip6e_dest2;
                        *mtod(exthdrs.ip6e_dest2, u_char *) = ip6->ip6_nxt;
                        ip6->ip6_nxt = IPPROTO_DSTOPTS;
                }

                /*
                 * Result: IPv6 hbh dest1 rthdr dest2 payload.
                 * m will point to IPv6 header.  mprev will point to the
                 * extension header prior to dest2 (rthdr in the above case).
                 */
                MAKE_CHAIN(exthdrs.ip6e_hbh, mprev, nexthdrp, IPPROTO_HOPOPTS);
                MAKE_CHAIN(exthdrs.ip6e_dest1, mprev, nexthdrp,
                           IPPROTO_DSTOPTS);
                MAKE_CHAIN(exthdrs.ip6e_rthdr, mprev, nexthdrp,
                           IPPROTO_ROUTING);
        }

        IP6STAT_INC(ip6s_localout);

        /* Route packet. */
        ro_pmtu = ro;
        if ((optvalid & IP6PO_VALID_RHINFO) != 0)
                ro = &opt->ip6po_route;
        if (ro != NULL)
                dst = (struct sockaddr_in6 *)&ro->ro_dst;
        else
                dst = &sin6;
        fibnum = (inp != NULL) ? inp->inp_inc.inc_fibnum : M_GETFIB(m);

again:
        /*
         * If specified, try to fill in the traffic class field.
         * Do not override if a non-zero value is already set.
         * We check the diffserv field and the ECN field separately.
         */
        if ((optvalid & IP6PO_VALID_TC) != 0){
                int mask = 0;

                if (IPV6_DSCP(ip6) == 0)
                        mask |= 0xfc;
                if (IPV6_ECN(ip6) == 0)
                        mask |= 0x03;
                if (mask != 0)
                        ip6->ip6_flow |= htonl((opt->ip6po_tclass & mask) << 20);
        }

        /* Fill in or override the hop limit field, if necessary. */
        if ((optvalid & IP6PO_VALID_HLIM) != 0)
                ip6->ip6_hlim = opt->ip6po_hlim & 0xff;
        else if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                if (im6o != NULL)
                        ip6->ip6_hlim = im6o->im6o_multicast_hlim;
                else
                        ip6->ip6_hlim = V_ip6_defmcasthlim;
        }

        if (ro == NULL || ro->ro_nh == NULL) {
                bzero(dst, sizeof(*dst));
                dst->sin6_family = AF_INET6;
                dst->sin6_len = sizeof(*dst);
                dst->sin6_addr = ip6->ip6_dst;
        } 
        /*
         * Validate route against routing table changes.
         * Make sure that the address family is set in route.
         */
        nh = NULL;
        ifp = NULL;
        mtu = 0;
        if (ro != NULL) {
                if (ro->ro_nh != NULL && inp != NULL) {
                        ro->ro_dst.sin6_family = AF_INET6; /* XXX KASSERT? */
                        NH_VALIDATE((struct route *)ro, &inp->inp_rt_cookie,
                            fibnum);
                }
                if (ro->ro_nh != NULL && fwd_tag == NULL &&
                    (!NH_IS_VALID(ro->ro_nh) ||
                    ro->ro_dst.sin6_family != AF_INET6 ||
                    !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, &ip6->ip6_dst)))
                        RO_INVALIDATE_CACHE(ro);

                if (ro->ro_nh != NULL && fwd_tag == NULL &&
                    ro->ro_dst.sin6_family == AF_INET6 &&
                    IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, &ip6->ip6_dst)) {
                        /* Nexthop is valid and contains valid ifp */
                        nh = ro->ro_nh;
                } else {
                        if (ro->ro_lle)
                                LLE_FREE(ro->ro_lle);   /* zeros ro_lle */
                        ro->ro_lle = NULL;
                        if (fwd_tag == NULL) {
                                bzero(&dst_sa, sizeof(dst_sa));
                                dst_sa.sin6_family = AF_INET6;
                                dst_sa.sin6_len = sizeof(dst_sa);
                                dst_sa.sin6_addr = ip6->ip6_dst;
                        }
                        error = in6_selectroute(&dst_sa, opt, im6o, ro, &ifp,
                            &nh, fibnum, m->m_pkthdr.flowid);
                        if (error != 0) {
                                IP6STAT_INC(ip6s_noroute);
                                if (ifp != NULL)
                                        in6_ifstat_inc(ifp, ifs6_out_discard);
                                goto bad;
                        }
                        /*
                         * At this point at least @ifp is not NULL
                         * Can be the case when dst is multicast, link-local or
                         * interface is explicitly specificed by the caller.
                         */
                }
                if (nh == NULL) {
                        /*
                         * If in6_selectroute() does not return a nexthop
                         * dst may not have been updated.
                         */
                        *dst = dst_sa;  /* XXX */
                        origifp = ifp;
                        mtu = ifp->if_mtu;
                } else {
                        ifp = nh->nh_ifp;
                        origifp = nh->nh_aifp;
                        ia = (struct in6_ifaddr *)(nh->nh_ifa);
                        counter_u64_add(nh->nh_pksent, 1);
                }
        } else {
                struct nhop_object *nh;
                struct in6_addr kdst;
                uint32_t scopeid;

                if (fwd_tag == NULL) {
                        bzero(&dst_sa, sizeof(dst_sa));
                        dst_sa.sin6_family = AF_INET6;
                        dst_sa.sin6_len = sizeof(dst_sa);
                        dst_sa.sin6_addr = ip6->ip6_dst;
                }

                if (IN6_IS_ADDR_MULTICAST(&dst_sa.sin6_addr) &&
                    im6o != NULL &&
                    (ifp = im6o->im6o_multicast_ifp) != NULL) {
                        /* We do not need a route lookup. */
                        *dst = dst_sa;  /* XXX */
                        origifp = ifp;
                        goto nonh6lookup;
                }

                in6_splitscope(&dst_sa.sin6_addr, &kdst, &scopeid);

                if (IN6_IS_ADDR_MC_LINKLOCAL(&dst_sa.sin6_addr) ||
                    IN6_IS_ADDR_MC_NODELOCAL(&dst_sa.sin6_addr)) {
                        if (scopeid > 0) {
                                ifp = in6_getlinkifnet(scopeid);
                                if (ifp == NULL) {
                                        error = EHOSTUNREACH;
                                        goto bad;
                                }
                                *dst = dst_sa;  /* XXX */
                                origifp = ifp;
                                goto nonh6lookup;
                        }
                }

                nh = fib6_lookup(fibnum, &kdst, scopeid, NHR_NONE,
                    m->m_pkthdr.flowid);
                if (nh == NULL) {
                        IP6STAT_INC(ip6s_noroute);
                        /* No ifp in6_ifstat_inc(ifp, ifs6_out_discard); */
                        error = EHOSTUNREACH;
                        goto bad;
                }

                ifp = nh->nh_ifp;
                origifp = nh->nh_aifp;
                ia = ifatoia6(nh->nh_ifa);
                if (nh->nh_flags & NHF_GATEWAY)
                        dst->sin6_addr = nh->gw6_sa.sin6_addr;
                else if (fwd_tag != NULL)
                        dst->sin6_addr = dst_sa.sin6_addr;
nonh6lookup:
                ;
        }
        /*
         * At this point ifp MUST be pointing to the valid transmit ifp.
         * origifp MUST be valid and pointing to either the same ifp or,
         * in case of loopback output, to the interface which ip6_src
         * belongs to.
         * Examples:
         *  fe80::1%em0 -> fe80::2%em0 -> ifp=em0, origifp=em0
         *  fe80::1%em0 -> fe80::1%em0 -> ifp=lo0, origifp=em0
         *  ::1 -> ::1 -> ifp=lo0, origifp=lo0
         *
         * mtu can be 0 and will be refined later.
         */
        KASSERT((ifp != NULL), ("output interface must not be NULL"));
        KASSERT((origifp != NULL), ("output address interface must not be NULL"));

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
        /*
         * IPSec checking which handles several cases.
         * FAST IPSEC: We re-injected the packet.
         * XXX: need scope argument.
         */
        if (IPSEC_ENABLED(ipv6)) {
                if ((error = IPSEC_OUTPUT(ipv6, ifp, m, inp, mtu == 0 ?
                    ifp->if_mtu : mtu)) != 0) {
                        if (error == EINPROGRESS)
                                error = 0;
                        goto done;
                }
        }
#endif /* IPSEC */

        if ((flags & IPV6_FORWARDING) == 0) {
                /* XXX: the FORWARDING flag can be set for mrouting. */
                in6_ifstat_inc(ifp, ifs6_out_request);
        }

        /* Setup data structures for scope ID checks. */
        src0 = ip6->ip6_src;
        bzero(&src_sa, sizeof(src_sa));
        src_sa.sin6_family = AF_INET6;
        src_sa.sin6_len = sizeof(src_sa);
        src_sa.sin6_addr = ip6->ip6_src;

        dst0 = ip6->ip6_dst;
        /* Re-initialize to be sure. */
        bzero(&dst_sa, sizeof(dst_sa));
        dst_sa.sin6_family = AF_INET6;
        dst_sa.sin6_len = sizeof(dst_sa);
        dst_sa.sin6_addr = ip6->ip6_dst;

        /* Check for valid scope ID. */
        if (in6_setscope(&src0, origifp, &zone) == 0 &&
            sa6_recoverscope(&src_sa) == 0 && zone == src_sa.sin6_scope_id &&
            in6_setscope(&dst0, origifp, &zone) == 0 &&
            sa6_recoverscope(&dst_sa) == 0 && zone == dst_sa.sin6_scope_id) {
                /*
                 * The outgoing interface is in the zone of the source
                 * and destination addresses.
                 *
                 */
        } else if ((origifp->if_flags & IFF_LOOPBACK) == 0 ||
            sa6_recoverscope(&src_sa) != 0 ||
            sa6_recoverscope(&dst_sa) != 0 ||
            dst_sa.sin6_scope_id == 0 ||
            (src_sa.sin6_scope_id != 0 &&
            src_sa.sin6_scope_id != dst_sa.sin6_scope_id) ||
            ifnet_byindex(dst_sa.sin6_scope_id) == NULL) {
                /*
                 * If the destination network interface is not a
                 * loopback interface, or the destination network
                 * address has no scope ID, or the source address has
                 * a scope ID set which is different from the
                 * destination address one, or there is no network
                 * interface representing this scope ID, the address
                 * pair is considered invalid.
                 */
                IP6STAT_INC(ip6s_badscope);
                in6_ifstat_inc(origifp, ifs6_out_discard);
                if (error == 0)
                        error = EHOSTUNREACH; /* XXX */
                goto bad;
        }
        /* All scope ID checks are successful. */

        if (nh && !IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                if ((optvalid & IP6PO_VALID_NHINFO) != 0) {
                        /*
                         * The nexthop is explicitly specified by the
                         * application.  We assume the next hop is an IPv6
                         * address.
                         */
                        dst = (struct sockaddr_in6 *)opt->ip6po_nexthop;
                }
                else if ((nh->nh_flags & NHF_GATEWAY))
                        dst = &nh->gw6_sa;
        }

        if (!IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                m->m_flags &= ~(M_BCAST | M_MCAST); /* Just in case. */
        } else {
                m->m_flags = (m->m_flags & ~M_BCAST) | M_MCAST;
                in6_ifstat_inc(ifp, ifs6_out_mcast);

                /* Confirm that the outgoing interface supports multicast. */
                if (!(ifp->if_flags & IFF_MULTICAST)) {
                        IP6STAT_INC(ip6s_noroute);
                        in6_ifstat_inc(ifp, ifs6_out_discard);
                        error = ENETUNREACH;
                        goto bad;
                }
                if ((im6o == NULL && in6_mcast_loop) ||
                    (im6o && im6o->im6o_multicast_loop)) {
                        /*
                         * Loop back multicast datagram if not expressly
                         * forbidden to do so, even if we have not joined
                         * the address; protocols will filter it later,
                         * thus deferring a hash lookup and lock acquisition
                         * at the expense of an m_copym().
                         */
                        ip6_mloopback(ifp, m);
                } else {
                        /*
                         * If we are acting as a multicast router, perform
                         * multicast forwarding as if the packet had just
                         * arrived on the interface to which we are about
                         * to send.  The multicast forwarding function
                         * recursively calls this function, using the
                         * IPV6_FORWARDING flag to prevent infinite recursion.
                         *
                         * Multicasts that are looped back by ip6_mloopback(),
                         * above, will be forwarded by the ip6_input() routine,
                         * if necessary.
                         */
                        if (V_ip6_mrouting_enabled &&
                            (flags & IPV6_FORWARDING) == 0) {
                                /*
                                 * XXX: ip6_mforward expects that rcvif is NULL
                                 * when it is called from the originating path.
                                 * However, it may not always be the case.
                                 */
                                m->m_pkthdr.rcvif = NULL;
                                if (ip6_mforward(ip6, ifp, m) != 0) {
                                        m_freem(m);
                                        goto done;
                                }
                        }
                }
                /*
                 * Multicasts with a hoplimit of zero may be looped back,
                 * above, but must not be transmitted on a network.
                 * Also, multicasts addressed to the loopback interface
                 * are not sent -- the above call to ip6_mloopback() will
                 * loop back a copy if this host actually belongs to the
                 * destination group on the loopback interface.
                 */
                if (ip6->ip6_hlim == 0 || (ifp->if_flags & IFF_LOOPBACK) ||
                    IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst)) {
                        m_freem(m);
                        goto done;
                }
        }

        /*
         * Fill the outgoing inteface to tell the upper layer
         * to increment per-interface statistics.
         */
        if (ifpp)
                *ifpp = ifp;

        /* Determine path MTU. */
        ip6_getpmtu(ro_pmtu, ro != ro_pmtu, ifp, &ip6->ip6_dst, &mtu, fibnum,
            *nexthdrp);
        KASSERT(mtu > 0, ("%s:%d: mtu %ld, ro_pmtu %p ro %p ifp %p fibnum %u",
            __func__, __LINE__, mtu, ro_pmtu, ro, ifp, fibnum));

        /*
         * The caller of this function may specify to use the minimum MTU
         * in some cases.
         * An advanced API option (IPV6_USE_MIN_MTU) can also override MTU
         * setting.  The logic is a bit complicated; by default, unicast
         * packets will follow path MTU while multicast packets will be sent at
         * the minimum MTU.  If IP6PO_MINMTU_ALL is specified, all packets
         * including unicast ones will be sent at the minimum MTU.  Multicast
         * packets will always be sent at the minimum MTU unless
         * IP6PO_MINMTU_DISABLE is explicitly specified.
         * See RFC 3542 for more details.
         */
        if (mtu > IPV6_MMTU) {
                if ((flags & IPV6_MINMTU))
                        mtu = IPV6_MMTU;
                else if (opt && opt->ip6po_minmtu == IP6PO_MINMTU_ALL)
                        mtu = IPV6_MMTU;
                else if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
                         (opt == NULL ||
                          opt->ip6po_minmtu != IP6PO_MINMTU_DISABLE)) {
                        mtu = IPV6_MMTU;
                }
        }

        /*
         * Clear embedded scope identifiers if necessary.
         * in6_clearscope() will touch the addresses only when necessary.
         */
        in6_clearscope(&ip6->ip6_src);
        in6_clearscope(&ip6->ip6_dst);

        /*
         * If the outgoing packet contains a hop-by-hop options header,
         * it must be examined and processed even by the source node.
         * (RFC 2460, section 4.)
         */
        if (exthdrs.ip6e_hbh) {
                struct ip6_hbh *hbh = mtod(exthdrs.ip6e_hbh, struct ip6_hbh *);
                u_int32_t dummy; /* XXX unused */

#ifdef DIAGNOSTIC
                if ((hbh->ip6h_len + 1) << 3 > exthdrs.ip6e_hbh->m_len)
                        panic("ip6e_hbh is not contiguous");
#endif
                /*
                 *  XXX: if we have to send an ICMPv6 error to the sender,
                 *       we need the M_LOOP flag since icmp6_error() expects
                 *       the IPv6 and the hop-by-hop options header are
                 *       contiguous unless the flag is set.
                 */
                m->m_flags |= M_LOOP;
                m->m_pkthdr.rcvif = ifp;
                if (ip6_process_hopopts(m, (u_int8_t *)(hbh + 1),
                    ((hbh->ip6h_len + 1) << 3) - sizeof(struct ip6_hbh),
                    &dummy) < 0) {
                        /* m was already freed at this point. */
                        error = EINVAL;/* better error? */
                        goto done;
                }
                m->m_flags &= ~M_LOOP; /* XXX */
                m->m_pkthdr.rcvif = NULL;
        }

        /* Jump over all PFIL processing if hooks are not active. */
        if (!PFIL_HOOKED_OUT(V_inet6_pfil_head))
                goto passout;

        odst = ip6->ip6_dst;
        /* Run through list of hooks for output packets. */
        switch (pfil_mbuf_out(V_inet6_pfil_head, &m, ifp, inp)) {
        case PFIL_PASS:
                ip6 = mtod(m, struct ip6_hdr *);
                break;
        case PFIL_DROPPED:
                error = EACCES;
                /* FALLTHROUGH */
        case PFIL_CONSUMED:
                goto done;
        }

        needfiblookup = 0;
        /* See if destination IP address was changed by packet filter. */
        if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) {
                m->m_flags |= M_SKIP_FIREWALL;
                /* If destination is now ourself drop to ip6_input(). */
                if (in6_localip(&ip6->ip6_dst)) {
                        m->m_flags |= M_FASTFWD_OURS;
                        if (m->m_pkthdr.rcvif == NULL)
                                m->m_pkthdr.rcvif = V_loif;
                        if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
                                m->m_pkthdr.csum_flags |=
                                    CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
                                m->m_pkthdr.csum_data = 0xffff;
                        }
#if defined(SCTP) || defined(SCTP_SUPPORT)
                        if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
                                m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
#endif
                        error = netisr_queue(NETISR_IPV6, m);
                        goto done;
                } else {
                        if (ro != NULL)
                                RO_INVALIDATE_CACHE(ro);
                        needfiblookup = 1; /* Redo the routing table lookup. */
                }
        }
        /* See if fib was changed by packet filter. */
        if (fibnum != M_GETFIB(m)) {
                m->m_flags |= M_SKIP_FIREWALL;
                fibnum = M_GETFIB(m);
                if (ro != NULL)
                        RO_INVALIDATE_CACHE(ro);
                needfiblookup = 1;
        }
        if (needfiblookup)
                goto again;

        /* See if local, if yes, send it to netisr. */
        if (m->m_flags & M_FASTFWD_OURS) {
                if (m->m_pkthdr.rcvif == NULL)
                        m->m_pkthdr.rcvif = V_loif;
                if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
                        m->m_pkthdr.csum_flags |=
                            CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
                        m->m_pkthdr.csum_data = 0xffff;
                }
#if defined(SCTP) || defined(SCTP_SUPPORT)
                if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
                        m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
#endif
                error = netisr_queue(NETISR_IPV6, m);
                goto done;
        }
        /* Or forward to some other address? */
        if ((m->m_flags & M_IP6_NEXTHOP) &&
            (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
                if (ro != NULL)
                        dst = (struct sockaddr_in6 *)&ro->ro_dst;
                else
                        dst = &sin6;
                bcopy((fwd_tag+1), &dst_sa, sizeof(struct sockaddr_in6));
                m->m_flags |= M_SKIP_FIREWALL;
                m->m_flags &= ~M_IP6_NEXTHOP;
                m_tag_delete(m, fwd_tag);
                goto again;
        }

passout:
        if (vlan_pcp > -1)
                EVL_APPLY_PRI(m, vlan_pcp);

        /* Ensure the packet data is mapped if the interface requires it. */
        if ((ifp->if_capenable & IFCAP_MEXTPG) == 0) {
                struct mbuf *m1;

                error = mb_unmapped_to_ext(m, &m1);
                if (error != 0) {
                        if (error == EINVAL) {
                                if_printf(ifp, "TLS packet\n");
                                /* XXXKIB */
                        } else if (error == ENOMEM) {
                                error = ENOBUFS;
                        }
                        IP6STAT_INC(ip6s_odropped);
                        return (error);
                } else {
                        m = m1;
                }
        }

        /*
         * Send the packet to the outgoing interface.
         * If necessary, do IPv6 fragmentation before sending.
         *
         * 1: normal case (dontfrag == 0)
         * 1-a: send as is if tlen <= path mtu
         * 1-b: fragment if tlen > path mtu
         *
         * 2: if user asks us not to fragment (dontfrag == 1)
         * 2-a: send as is if tlen <= interface mtu
         * 2-b: error if tlen > interface mtu
         */
        sw_csum = m->m_pkthdr.csum_flags;
        if (!hdrsplit) {
                tso = ((sw_csum & ifp->if_hwassist &
                    (CSUM_TSO | CSUM_INNER_TSO)) != 0) ? 1 : 0;
                sw_csum &= ~ifp->if_hwassist;
        } else
                tso = 0;
        /*
         * If we added extension headers, we will not do TSO and calculate the
         * checksums ourselves for now.
         * XXX-BZ  Need a framework to know when the NIC can handle it, even
         * with ext. hdrs.
         */
        ip6_output_delayed_csum(m, ifp, sw_csum, plen, optlen);
        /* XXX-BZ m->m_pkthdr.csum_flags &= ~ifp->if_hwassist; */
        tlen = m->m_pkthdr.len;

        if ((opt && (opt->ip6po_flags & IP6PO_DONTFRAG)) || tso)
                dontfrag = 1;
        else
                dontfrag = 0;
        if (dontfrag && tlen > in6_ifmtu(ifp) && !tso) {        /* Case 2-b. */
                /*
                 * If the DONTFRAG option is specified, we cannot send the
                 * packet when the data length is larger than the MTU of the
                 * outgoing interface.
                 * Notify the error by sending IPV6_PATHMTU ancillary data if
                 * application wanted to know the MTU value. Also return an
                 * error code (this is not described in the API spec).
                 */
                if (inp != NULL)
                        ip6_notify_pmtu(inp, &dst_sa, (u_int32_t)mtu);
                error = EMSGSIZE;
                goto bad;
        }

        /* Transmit packet without fragmentation. */
        if (dontfrag || tlen <= mtu) {  /* Cases 1-a and 2-a. */
                struct in6_ifaddr *ia6;

                ip6 = mtod(m, struct ip6_hdr *);
                ia6 = in6_ifawithifp(ifp, &ip6->ip6_src);
                if (ia6) {
                        /* Record statistics for this interface address. */
                        counter_u64_add(ia6->ia_ifa.ifa_opackets, 1);
                        counter_u64_add(ia6->ia_ifa.ifa_obytes,
                            m->m_pkthdr.len);
                }
                error = ip6_output_send(inp, ifp, origifp, m, dst, ro,
                    (flags & IP_NO_SND_TAG_RL) ? false : true);
                goto done;
        }

        /* Try to fragment the packet.  Case 1-b. */
        if (mtu < IPV6_MMTU) {
                /* Path MTU cannot be less than IPV6_MMTU. */
                error = EMSGSIZE;
                in6_ifstat_inc(ifp, ifs6_out_fragfail);
                goto bad;
        } else if (ip6->ip6_plen == 0) {
                /* We do not support jumbo payload. */
                error = EMSGSIZE;
                in6_ifstat_inc(ifp, ifs6_out_fragfail);
                goto bad;
        } else {
                u_char nextproto;

                /*
                 * Too large for the destination or interface;
                 * fragment if possible.
                 * Must be able to put at least 8 bytes per fragment.
                 */
                if (mtu > IPV6_MAXPACKET)
                        mtu = IPV6_MAXPACKET;

                len = (mtu - unfragpartlen - sizeof(struct ip6_frag)) & ~7;
                if (len < 8) {
                        error = EMSGSIZE;
                        in6_ifstat_inc(ifp, ifs6_out_fragfail);
                        goto bad;
                }

                /*
                 * If the interface will not calculate checksums on
                 * fragmented packets, then do it here.
                 * XXX-BZ handle the hw offloading case.  Need flags.
                 */
                ip6_output_delayed_csum(m, ifp, m->m_pkthdr.csum_flags, plen,
                    optlen);

                /*
                 * Change the next header field of the last header in the
                 * unfragmentable part.
                 */
                if (exthdrs.ip6e_rthdr) {
                        nextproto = *mtod(exthdrs.ip6e_rthdr, u_char *);
                        *mtod(exthdrs.ip6e_rthdr, u_char *) = IPPROTO_FRAGMENT;
                } else if (exthdrs.ip6e_dest1) {
                        nextproto = *mtod(exthdrs.ip6e_dest1, u_char *);
                        *mtod(exthdrs.ip6e_dest1, u_char *) = IPPROTO_FRAGMENT;
                } else if (exthdrs.ip6e_hbh) {
                        nextproto = *mtod(exthdrs.ip6e_hbh, u_char *);
                        *mtod(exthdrs.ip6e_hbh, u_char *) = IPPROTO_FRAGMENT;
                } else {
                        ip6 = mtod(m, struct ip6_hdr *);
                        nextproto = ip6->ip6_nxt;
                        ip6->ip6_nxt = IPPROTO_FRAGMENT;
                }

                /*
                 * Loop through length of segment after first fragment,
                 * make new header and copy data of each part and link onto
                 * chain.
                 */
                m0 = m;
                id = htonl(ip6_randomid());
                error = ip6_fragment(ifp, m, unfragpartlen, nextproto,len, id);
                if (error != 0)
                        goto sendorfree;

                in6_ifstat_inc(ifp, ifs6_out_fragok);
        }

        /* Remove leading garbage. */
sendorfree:
        m = m0->m_nextpkt;
        m0->m_nextpkt = 0;
        m_freem(m0);
        for (; m; m = m0) {
                m0 = m->m_nextpkt;
                m->m_nextpkt = 0;
                if (error == 0) {
                        /* Record statistics for this interface address. */
                        if (ia) {
                                counter_u64_add(ia->ia_ifa.ifa_opackets, 1);
                                counter_u64_add(ia->ia_ifa.ifa_obytes,
                                    m->m_pkthdr.len);
                        }
                        if (vlan_pcp > -1)
                                EVL_APPLY_PRI(m, vlan_pcp);
                        error = ip6_output_send(inp, ifp, origifp, m, dst, ro,
                            true);
                } else
                        m_freem(m);
        }

        if (error == 0)
                IP6STAT_INC(ip6s_fragmented);

done:
        return (error);

freehdrs:
        m_freem(exthdrs.ip6e_hbh);      /* m_freem() checks if mbuf is NULL. */
        m_freem(exthdrs.ip6e_dest1);
        m_freem(exthdrs.ip6e_rthdr);
        m_freem(exthdrs.ip6e_dest2);
        /* FALLTHROUGH */
bad:
        if (m)
                m_freem(m);
        goto done;
}

static int
ip6_copyexthdr(struct mbuf **mp, caddr_t hdr, int hlen)
{
        struct mbuf *m;

        if (hlen > MCLBYTES)
                return (ENOBUFS); /* XXX */

        if (hlen > MLEN)
                m = m_getcl(M_NOWAIT, MT_DATA, 0);
        else
                m = m_get(M_NOWAIT, MT_DATA);
        if (m == NULL)
                return (ENOBUFS);
        m->m_len = hlen;
        if (hdr)
                bcopy(hdr, mtod(m, caddr_t), hlen);

        *mp = m;
        return (0);
}

/*
 * Insert fragment header and copy unfragmentable header portions.
 */
static int
ip6_insertfraghdr(struct mbuf *m0, struct mbuf *m, int hlen,
    struct ip6_frag **frghdrp)
{
        struct mbuf *n, *mlast;

        if (hlen > sizeof(struct ip6_hdr)) {
                n = m_copym(m0, sizeof(struct ip6_hdr),
                    hlen - sizeof(struct ip6_hdr), M_NOWAIT);
                if (n == NULL)
                        return (ENOBUFS);
                m->m_next = n;
        } else
                n = m;

        /* Search for the last mbuf of unfragmentable part. */
        for (mlast = n; mlast->m_next; mlast = mlast->m_next)
                ;

        if (M_WRITABLE(mlast) &&
            M_TRAILINGSPACE(mlast) >= sizeof(struct ip6_frag)) {
                /* use the trailing space of the last mbuf for the fragment hdr */
                *frghdrp = (struct ip6_frag *)(mtod(mlast, caddr_t) +
                    mlast->m_len);
                mlast->m_len += sizeof(struct ip6_frag);
                m->m_pkthdr.len += sizeof(struct ip6_frag);
        } else {
                /* allocate a new mbuf for the fragment header */
                struct mbuf *mfrg;

                mfrg = m_get(M_NOWAIT, MT_DATA);
                if (mfrg == NULL)
                        return (ENOBUFS);
                mfrg->m_len = sizeof(struct ip6_frag);
                *frghdrp = mtod(mfrg, struct ip6_frag *);
                mlast->m_next = mfrg;
        }

        return (0);
}

/*
 * Calculates IPv6 path mtu for destination @dst.
 * Resulting MTU is stored in @mtup.
 *
 * Returns 0 on success.
 */
static int
ip6_getpmtu_ctl(u_int fibnum, const struct in6_addr *dst, u_long *mtup)
{
        struct epoch_tracker et;
        struct nhop_object *nh;
        struct in6_addr kdst;
        uint32_t scopeid;
        int error;

        in6_splitscope(dst, &kdst, &scopeid);

        NET_EPOCH_ENTER(et);
        nh = fib6_lookup(fibnum, &kdst, scopeid, NHR_NONE, 0);
        if (nh != NULL) {
                ip6_calcmtu(nh->nh_ifp, dst, nh->nh_mtu, mtup, 0);
                error = 0;
        } else
                error = EHOSTUNREACH;
        NET_EPOCH_EXIT(et);

        return (error);
}

/*
 * Calculates IPv6 path MTU for @dst based on transmit @ifp,
 * and cached data in @ro_pmtu.
 * MTU from (successful) route lookup is saved (along with dst)
 * inside @ro_pmtu to avoid subsequent route lookups after packet
 * filter processing.
 *
 * Stores mtu into @mtup.
 */
static void
ip6_getpmtu(struct route_in6 *ro_pmtu, int do_lookup,
    struct ifnet *ifp, const struct in6_addr *dst, u_long *mtup,
    u_int fibnum, u_int proto)
{
        struct nhop_object *nh;
        struct in6_addr kdst;
        uint32_t scopeid;
        struct sockaddr_in6 *sa6_dst, sin6;
        u_long mtu;

        NET_EPOCH_ASSERT();

        mtu = 0;
        if (ro_pmtu == NULL || do_lookup) {
                /*
                 * Here ro_pmtu has final destination address, while
                 * ro might represent immediate destination.
                 * Use ro_pmtu destination since mtu might differ.
                 */
                if (ro_pmtu != NULL) {
                        sa6_dst = (struct sockaddr_in6 *)&ro_pmtu->ro_dst;
                        if (!IN6_ARE_ADDR_EQUAL(&sa6_dst->sin6_addr, dst))
                                ro_pmtu->ro_mtu = 0;
                } else
                        sa6_dst = &sin6;

                if (ro_pmtu == NULL || ro_pmtu->ro_mtu == 0) {
                        bzero(sa6_dst, sizeof(*sa6_dst));
                        sa6_dst->sin6_family = AF_INET6;
                        sa6_dst->sin6_len = sizeof(struct sockaddr_in6);
                        sa6_dst->sin6_addr = *dst;

                        in6_splitscope(dst, &kdst, &scopeid);
                        nh = fib6_lookup(fibnum, &kdst, scopeid, NHR_NONE, 0);
                        if (nh != NULL) {
                                mtu = nh->nh_mtu;
                                if (ro_pmtu != NULL)
                                        ro_pmtu->ro_mtu = mtu;
                        }
                } else
                        mtu = ro_pmtu->ro_mtu;
        }

        if (ro_pmtu != NULL && ro_pmtu->ro_nh != NULL)
                mtu = ro_pmtu->ro_nh->nh_mtu;

        ip6_calcmtu(ifp, dst, mtu, mtup, proto);
}

/*
 * Calculate MTU based on transmit @ifp, route mtu @rt_mtu and
 * hostcache data for @dst.
 * Stores mtu into @mtup.
 */
static void
ip6_calcmtu(struct ifnet *ifp, const struct in6_addr *dst, u_long rt_mtu,
    u_long *mtup, u_int proto)
{
        u_long mtu = 0;

        if (rt_mtu > 0) {
                /* Skip the hostcache if the protocol handles PMTU changes. */
                if (proto != IPPROTO_TCP && proto != IPPROTO_SCTP) {
                        struct in_conninfo inc = {
                            .inc_flags = INC_ISIPV6,
                            .inc6_faddr = *dst,
                        };

                        mtu = tcp_hc_getmtu(&inc);
                }

                if (mtu)
                        mtu = min(mtu, rt_mtu);
                else
                        mtu = rt_mtu;
        }

        if (mtu == 0)
                mtu = in6_ifmtu(ifp);

        *mtup = mtu;
}

/*
 * IP6 socket option processing.
 */
int
ip6_ctloutput(struct socket *so, struct sockopt *sopt)
{
        int optdatalen, uproto;
        void *optdata;
        struct inpcb *inp = sotoinpcb(so);
        int error, optval;
        int level, op, optname;
        int optlen;
        struct thread *td;
#ifdef  RSS
        uint32_t rss_bucket;
        int retval;
#endif

/*
 * Don't use more than a quarter of mbuf clusters.  N.B.:
 * nmbclusters is an int, but nmbclusters * MCLBYTES may overflow
 * on LP64 architectures, so cast to u_long to avoid undefined
 * behavior.  ILP32 architectures cannot have nmbclusters
 * large enough to overflow for other reasons.
 */
#define IPV6_PKTOPTIONS_MBUF_LIMIT      ((u_long)nmbclusters * MCLBYTES / 4)

        level = sopt->sopt_level;
        op = sopt->sopt_dir;
        optname = sopt->sopt_name;
        optlen = sopt->sopt_valsize;
        td = sopt->sopt_td;
        error = 0;
        optval = 0;
        uproto = (int)so->so_proto->pr_protocol;

        if (level != IPPROTO_IPV6) {
                error = EINVAL;

                if (sopt->sopt_level == SOL_SOCKET &&
                    sopt->sopt_dir == SOPT_SET) {
                        switch (sopt->sopt_name) {
                        case SO_SETFIB:
                                error = sooptcopyin(sopt, &optval,
                                    sizeof(optval), sizeof(optval));
                                if (error != 0)
                                        break;

                                INP_WLOCK(inp);
                                if ((inp->inp_flags & INP_BOUNDFIB) != 0 &&
                                    optval != so->so_fibnum) {
                                        INP_WUNLOCK(inp);
                                        error = EISCONN;
                                        break;
                                }
                                error = sosetfib(inp->inp_socket, optval);
                                if (error == 0)
                                        inp->inp_inc.inc_fibnum = optval;
                                INP_WUNLOCK(inp);
                                break;
                        case SO_MAX_PACING_RATE:
#ifdef RATELIMIT
                                INP_WLOCK(inp);
                                inp->inp_flags2 |= INP_RATE_LIMIT_CHANGED;
                                INP_WUNLOCK(inp);
                                error = 0;
#else
                                error = EOPNOTSUPP;
#endif
                                break;
                        default:
                                break;
                        }
                }
        } else {                /* level == IPPROTO_IPV6 */
                switch (op) {
                case SOPT_SET:
                        switch (optname) {
                        case IPV6_2292PKTOPTIONS:
#ifdef IPV6_PKTOPTIONS
                        case IPV6_PKTOPTIONS:
#endif
                        {
                                struct mbuf *m;

                                if (optlen > IPV6_PKTOPTIONS_MBUF_LIMIT) {
                                        printf("ip6_ctloutput: mbuf limit hit\n");
                                        error = ENOBUFS;
                                        break;
                                }

                                error = soopt_getm(sopt, &m); /* XXX */
                                if (error != 0)
                                        break;
                                error = soopt_mcopyin(sopt, m); /* XXX */
                                if (error != 0)
                                        break;
                                INP_WLOCK(inp);
                                error = ip6_pcbopts(&inp->in6p_outputopts, m,
                                    so, sopt);
                                INP_WUNLOCK(inp);
                                m_freem(m); /* XXX */
                                break;
                        }

                        /*
                         * Use of some Hop-by-Hop options or some
                         * Destination options, might require special
                         * privilege.  That is, normal applications
                         * (without special privilege) might be forbidden
                         * from setting certain options in outgoing packets,
                         * and might never see certain options in received
                         * packets. [RFC 2292 Section 6]
                         * KAME specific note:
                         *  KAME prevents non-privileged users from sending or
                         *  receiving ANY hbh/dst options in order to avoid
                         *  overhead of parsing options in the kernel.
                         */
                        case IPV6_RECVHOPOPTS:
                        case IPV6_RECVDSTOPTS:
                        case IPV6_RECVRTHDRDSTOPTS:
                                if (td != NULL) {
                                        error = priv_check(td,
                                            PRIV_NETINET_SETHDROPTS);
                                        if (error)
                                                break;
                                }
                                /* FALLTHROUGH */
                        case IPV6_UNICAST_HOPS:
                        case IPV6_HOPLIMIT:

                        case IPV6_RECVPKTINFO:
                        case IPV6_RECVHOPLIMIT:
                        case IPV6_RECVRTHDR:
                        case IPV6_RECVPATHMTU:
                        case IPV6_RECVTCLASS:
                        case IPV6_RECVFLOWID:
#ifdef  RSS
                        case IPV6_RECVRSSBUCKETID:
#endif
                        case IPV6_V6ONLY:
                        case IPV6_AUTOFLOWLABEL:
                        case IPV6_ORIGDSTADDR:
                        case IPV6_BINDANY:
                        case IPV6_VLAN_PCP:
                                if (optname == IPV6_BINDANY && td != NULL) {
                                        error = priv_check(td,
                                            PRIV_NETINET_BINDANY);
                                        if (error)
                                                break;
                                }

                                if (optlen != sizeof(int)) {
                                        error = EINVAL;
                                        break;
                                }
                                error = sooptcopyin(sopt, &optval,
                                        sizeof optval, sizeof optval);
                                if (error)
                                        break;
                                switch (optname) {
                                case IPV6_UNICAST_HOPS:
                                        if (optval < -1 || optval >= 256)
                                                error = EINVAL;
                                        else {
                                                /* -1 = kernel default */
                                                inp->in6p_hops = optval;
                                                if ((inp->inp_vflag &
                                                     INP_IPV4) != 0)
                                                        inp->inp_ip_ttl = optval;
                                        }
                                        break;
#define OPTSET(bit) \
do { \
        INP_WLOCK(inp); \
        if (optval) \
                inp->inp_flags |= (bit); \
        else \
                inp->inp_flags &= ~(bit); \
        INP_WUNLOCK(inp); \
} while (/*CONSTCOND*/ 0)
#define OPTSET2292(bit) \
do { \
        INP_WLOCK(inp); \
        inp->inp_flags |= IN6P_RFC2292; \
        if (optval) \
                inp->inp_flags |= (bit); \
        else \
                inp->inp_flags &= ~(bit); \
        INP_WUNLOCK(inp); \
} while (/*CONSTCOND*/ 0)
#define OPTBIT(bit) (inp->inp_flags & (bit) ? 1 : 0)

#define OPTSET2_N(bit, val) do {                                        \
        if (val)                                                        \
                inp->inp_flags2 |= bit;                                 \
        else                                                            \
                inp->inp_flags2 &= ~bit;                                \
} while (0)
#define OPTSET2(bit, val) do {                                          \
        INP_WLOCK(inp);                                                 \
        OPTSET2_N(bit, val);                                            \
        INP_WUNLOCK(inp);                                               \
} while (0)
#define OPTBIT2(bit) (inp->inp_flags2 & (bit) ? 1 : 0)
#define OPTSET2292_EXCLUSIVE(bit)                                       \
do {                                                                    \
        INP_WLOCK(inp);                                                 \
        if (OPTBIT(IN6P_RFC2292)) {                                     \
                error = EINVAL;                                         \
        } else {                                                        \
                if (optval)                                             \
                        inp->inp_flags |= (bit);                        \
                else                                                    \
                        inp->inp_flags &= ~(bit);                       \
        }                                                               \
        INP_WUNLOCK(inp);                                               \
} while (/*CONSTCOND*/ 0)

                                case IPV6_RECVPKTINFO:
                                        OPTSET2292_EXCLUSIVE(IN6P_PKTINFO);
                                        break;

                                case IPV6_HOPLIMIT:
                                {
                                        struct ip6_pktopts **optp;

                                        /* cannot mix with RFC2292 */
                                        if (OPTBIT(IN6P_RFC2292)) {
                                                error = EINVAL;
                                                break;
                                        }
                                        INP_WLOCK(inp);
                                        if (inp->inp_flags & INP_DROPPED) {
                                                INP_WUNLOCK(inp);
                                                return (ECONNRESET);
                                        }
                                        optp = &inp->in6p_outputopts;
                                        error = ip6_pcbopt(IPV6_HOPLIMIT,
                                            (u_char *)&optval, sizeof(optval),
                                            optp, (td != NULL) ? td->td_ucred :
                                            NULL, uproto);
                                        INP_WUNLOCK(inp);
                                        break;
                                }

                                case IPV6_RECVHOPLIMIT:
                                        OPTSET2292_EXCLUSIVE(IN6P_HOPLIMIT);
                                        break;

                                case IPV6_RECVHOPOPTS:
                                        OPTSET2292_EXCLUSIVE(IN6P_HOPOPTS);
                                        break;

                                case IPV6_RECVDSTOPTS:
                                        OPTSET2292_EXCLUSIVE(IN6P_DSTOPTS);
                                        break;

                                case IPV6_RECVRTHDRDSTOPTS:
                                        OPTSET2292_EXCLUSIVE(IN6P_RTHDRDSTOPTS);
                                        break;

                                case IPV6_RECVRTHDR:
                                        OPTSET2292_EXCLUSIVE(IN6P_RTHDR);
                                        break;

                                case IPV6_RECVPATHMTU:
                                        /*
                                         * We ignore this option for TCP
                                         * sockets.
                                         * (RFC3542 leaves this case
                                         * unspecified.)
                                         */
                                        if (uproto != IPPROTO_TCP)
                                                OPTSET(IN6P_MTU);
                                        break;

                                case IPV6_RECVFLOWID:
                                        OPTSET2(INP_RECVFLOWID, optval);
                                        break;

#ifdef  RSS
                                case IPV6_RECVRSSBUCKETID:
                                        OPTSET2(INP_RECVRSSBUCKETID, optval);
                                        break;
#endif

                                case IPV6_V6ONLY:
                                        INP_WLOCK(inp);
                                        if (inp->inp_lport ||
                                            !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) {
                                                /*
                                                 * The socket is already bound.
                                                 */
                                                INP_WUNLOCK(inp);
                                                error = EINVAL;
                                                break;
                                        }
                                        if (optval) {
                                                inp->inp_flags |= IN6P_IPV6_V6ONLY;
                                                inp->inp_vflag &= ~INP_IPV4;
                                        } else {
                                                inp->inp_flags &= ~IN6P_IPV6_V6ONLY;
                                                inp->inp_vflag |= INP_IPV4;
                                        }
                                        INP_WUNLOCK(inp);
                                        break;
                                case IPV6_RECVTCLASS:
                                        /* cannot mix with RFC2292 XXX */
                                        OPTSET2292_EXCLUSIVE(IN6P_TCLASS);
                                        break;
                                case IPV6_AUTOFLOWLABEL:
                                        OPTSET(IN6P_AUTOFLOWLABEL);
                                        break;

                                case IPV6_ORIGDSTADDR:
                                        OPTSET2(INP_ORIGDSTADDR, optval);
                                        break;
                                case IPV6_BINDANY:
                                        OPTSET(INP_BINDANY);
                                        break;
                                case IPV6_VLAN_PCP:
                                        if ((optval >= -1) && (optval <=
                                            (INP_2PCP_MASK >> INP_2PCP_SHIFT))) {
                                                if (optval == -1) {
                                                        INP_WLOCK(inp);
                                                        inp->inp_flags2 &=
                                                            ~(INP_2PCP_SET |
                                                            INP_2PCP_MASK);
                                                        INP_WUNLOCK(inp);
                                                } else {
                                                        INP_WLOCK(inp);
                                                        inp->inp_flags2 |=
                                                            INP_2PCP_SET;
                                                        inp->inp_flags2 &=
                                                            ~INP_2PCP_MASK;
                                                        inp->inp_flags2 |=
                                                            optval <<
                                                            INP_2PCP_SHIFT;
                                                        INP_WUNLOCK(inp);
                                                }
                                        } else
                                                error = EINVAL;
                                        break;
                                }
                                break;

                        case IPV6_TCLASS:
                        case IPV6_DONTFRAG:
                        case IPV6_USE_MIN_MTU:
                        case IPV6_PREFER_TEMPADDR:
                                if (optlen != sizeof(optval)) {
                                        error = EINVAL;
                                        break;
                                }
                                error = sooptcopyin(sopt, &optval,
                                        sizeof optval, sizeof optval);
                                if (error)
                                        break;
                                {
                                        struct ip6_pktopts **optp;
                                        INP_WLOCK(inp);
                                        if (inp->inp_flags & INP_DROPPED) {
                                                INP_WUNLOCK(inp);
                                                return (ECONNRESET);
                                        }
                                        optp = &inp->in6p_outputopts;
                                        error = ip6_pcbopt(optname,
                                            (u_char *)&optval, sizeof(optval),
                                            optp, (td != NULL) ? td->td_ucred :
                                            NULL, uproto);
                                        INP_WUNLOCK(inp);
                                        break;
                                }

                        case IPV6_2292PKTINFO:
                        case IPV6_2292HOPLIMIT:
                        case IPV6_2292HOPOPTS:
                        case IPV6_2292DSTOPTS:
                        case IPV6_2292RTHDR:
                                /* RFC 2292 */
                                if (optlen != sizeof(int)) {
                                        error = EINVAL;
                                        break;
                                }
                                error = sooptcopyin(sopt, &optval,
                                        sizeof optval, sizeof optval);
                                if (error)
                                        break;
                                switch (optname) {
                                case IPV6_2292PKTINFO:
                                        OPTSET2292(IN6P_PKTINFO);
                                        break;
                                case IPV6_2292HOPLIMIT:
                                        OPTSET2292(IN6P_HOPLIMIT);
                                        break;
                                case IPV6_2292HOPOPTS:
                                        /*
                                         * Check super-user privilege.
                                         * See comments for IPV6_RECVHOPOPTS.
                                         */
                                        if (td != NULL) {
                                                error = priv_check(td,
                                                    PRIV_NETINET_SETHDROPTS);
                                                if (error)
                                                        return (error);
                                        }
                                        OPTSET2292(IN6P_HOPOPTS);
                                        break;
                                case IPV6_2292DSTOPTS:
                                        if (td != NULL) {
                                                error = priv_check(td,
                                                    PRIV_NETINET_SETHDROPTS);
                                                if (error)
                                                        return (error);
                                        }
                                        OPTSET2292(IN6P_DSTOPTS|IN6P_RTHDRDSTOPTS); /* XXX */
                                        break;
                                case IPV6_2292RTHDR:
                                        OPTSET2292(IN6P_RTHDR);
                                        break;
                                }
                                break;
                        case IPV6_PKTINFO:
                        case IPV6_HOPOPTS:
                        case IPV6_RTHDR:
                        case IPV6_DSTOPTS:
                        case IPV6_RTHDRDSTOPTS:
                        case IPV6_NEXTHOP:
                        {
                                /* new advanced API (RFC3542) */
                                u_char *optbuf;
                                u_char optbuf_storage[MCLBYTES];
                                int optlen;
                                struct ip6_pktopts **optp;

                                /* cannot mix with RFC2292 */
                                if (OPTBIT(IN6P_RFC2292)) {
                                        error = EINVAL;
                                        break;
                                }

                                /*
                                 * We only ensure valsize is not too large
                                 * here.  Further validation will be done
                                 * later.
                                 */
                                error = sooptcopyin(sopt, optbuf_storage,
                                    sizeof(optbuf_storage), 0);
                                if (error)
                                        break;
                                optlen = sopt->sopt_valsize;
                                optbuf = optbuf_storage;
                                INP_WLOCK(inp);
                                if (inp->inp_flags & INP_DROPPED) {
                                        INP_WUNLOCK(inp);
                                        return (ECONNRESET);
                                }
                                optp = &inp->in6p_outputopts;
                                error = ip6_pcbopt(optname, optbuf, optlen,
                                    optp, (td != NULL) ? td->td_ucred : NULL,
                                    uproto);
                                INP_WUNLOCK(inp);
                                break;
                        }
#undef OPTSET

                        case IPV6_MULTICAST_IF:
                        case IPV6_MULTICAST_HOPS:
                        case IPV6_MULTICAST_LOOP:
                        case IPV6_JOIN_GROUP:
                        case IPV6_LEAVE_GROUP:
                        case IPV6_MSFILTER:
                        case MCAST_BLOCK_SOURCE:
                        case MCAST_UNBLOCK_SOURCE:
                        case MCAST_JOIN_GROUP:
                        case MCAST_LEAVE_GROUP:
                        case MCAST_JOIN_SOURCE_GROUP:
                        case MCAST_LEAVE_SOURCE_GROUP:
                                error = ip6_setmoptions(inp, sopt);
                                break;

                        case IPV6_PORTRANGE:
                                error = sooptcopyin(sopt, &optval,
                                    sizeof optval, sizeof optval);
                                if (error)
                                        break;

                                INP_WLOCK(inp);
                                switch (optval) {
                                case IPV6_PORTRANGE_DEFAULT:
                                        inp->inp_flags &= ~(INP_LOWPORT);
                                        inp->inp_flags &= ~(INP_HIGHPORT);
                                        break;

                                case IPV6_PORTRANGE_HIGH:
                                        inp->inp_flags &= ~(INP_LOWPORT);
                                        inp->inp_flags |= INP_HIGHPORT;
                                        break;

                                case IPV6_PORTRANGE_LOW:
                                        inp->inp_flags &= ~(INP_HIGHPORT);
                                        inp->inp_flags |= INP_LOWPORT;
                                        break;

                                default:
                                        error = EINVAL;
                                        break;
                                }
                                INP_WUNLOCK(inp);
                                break;

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
                        case IPV6_IPSEC_POLICY:
                                if (IPSEC_ENABLED(ipv6)) {
                                        error = IPSEC_PCBCTL(ipv6, inp, sopt);
                                        break;
                                }
                                /* FALLTHROUGH */
#endif /* IPSEC */

                        default:
                                error = ENOPROTOOPT;
                                break;
                        }
                        break;

                case SOPT_GET:
                        switch (optname) {
                        case IPV6_2292PKTOPTIONS:
#ifdef IPV6_PKTOPTIONS
                        case IPV6_PKTOPTIONS:
#endif
                                /*
                                 * RFC3542 (effectively) deprecated the
                                 * semantics of the 2292-style pktoptions.
                                 * Since it was not reliable in nature (i.e.,
                                 * applications had to expect the lack of some
                                 * information after all), it would make sense
                                 * to simplify this part by always returning
                                 * empty data.
                                 */
                                sopt->sopt_valsize = 0;
                                break;

                        case IPV6_RECVHOPOPTS:
                        case IPV6_RECVDSTOPTS:
                        case IPV6_RECVRTHDRDSTOPTS:
                        case IPV6_UNICAST_HOPS:
                        case IPV6_RECVPKTINFO:
                        case IPV6_RECVHOPLIMIT:
                        case IPV6_RECVRTHDR:
                        case IPV6_RECVPATHMTU:

                        case IPV6_V6ONLY:
                        case IPV6_PORTRANGE:
                        case IPV6_RECVTCLASS:
                        case IPV6_AUTOFLOWLABEL:
                        case IPV6_BINDANY:
                        case IPV6_FLOWID:
                        case IPV6_FLOWTYPE:
                        case IPV6_RECVFLOWID:
#ifdef  RSS
                        case IPV6_RSSBUCKETID:
                        case IPV6_RECVRSSBUCKETID:
#endif
                        case IPV6_VLAN_PCP:
                                switch (optname) {
                                case IPV6_RECVHOPOPTS:
                                        optval = OPTBIT(IN6P_HOPOPTS);
                                        break;

                                case IPV6_RECVDSTOPTS:
                                        optval = OPTBIT(IN6P_DSTOPTS);
                                        break;

                                case IPV6_RECVRTHDRDSTOPTS:
                                        optval = OPTBIT(IN6P_RTHDRDSTOPTS);
                                        break;

                                case IPV6_UNICAST_HOPS:
                                        optval = inp->in6p_hops;
                                        break;

                                case IPV6_RECVPKTINFO:
                                        optval = OPTBIT(IN6P_PKTINFO);
                                        break;

                                case IPV6_RECVHOPLIMIT:
                                        optval = OPTBIT(IN6P_HOPLIMIT);
                                        break;

                                case IPV6_RECVRTHDR:
                                        optval = OPTBIT(IN6P_RTHDR);
                                        break;

                                case IPV6_RECVPATHMTU:
                                        optval = OPTBIT(IN6P_MTU);
                                        break;

                                case IPV6_V6ONLY:
                                        optval = OPTBIT(IN6P_IPV6_V6ONLY);
                                        break;

                                case IPV6_PORTRANGE:
                                    {
                                        int flags;
                                        flags = inp->inp_flags;
                                        if (flags & INP_HIGHPORT)
                                                optval = IPV6_PORTRANGE_HIGH;
                                        else if (flags & INP_LOWPORT)
                                                optval = IPV6_PORTRANGE_LOW;
                                        else
                                                optval = 0;
                                        break;
                                    }
                                case IPV6_RECVTCLASS:
                                        optval = OPTBIT(IN6P_TCLASS);
                                        break;

                                case IPV6_AUTOFLOWLABEL:
                                        optval = OPTBIT(IN6P_AUTOFLOWLABEL);
                                        break;

                                case IPV6_ORIGDSTADDR:
                                        optval = OPTBIT2(INP_ORIGDSTADDR);
                                        break;

                                case IPV6_BINDANY:
                                        optval = OPTBIT(INP_BINDANY);
                                        break;

                                case IPV6_FLOWID:
                                        optval = inp->inp_flowid;
                                        break;

                                case IPV6_FLOWTYPE:
                                        optval = inp->inp_flowtype;
                                        break;

                                case IPV6_RECVFLOWID:
                                        optval = OPTBIT2(INP_RECVFLOWID);
                                        break;
#ifdef  RSS
                                case IPV6_RSSBUCKETID:
                                        retval =
                                            rss_hash2bucket(inp->inp_flowid,
                                            inp->inp_flowtype,
                                            &rss_bucket);
                                        if (retval == 0)
                                                optval = rss_bucket;
                                        else
                                                error = EINVAL;
                                        break;

                                case IPV6_RECVRSSBUCKETID:
                                        optval = OPTBIT2(INP_RECVRSSBUCKETID);
                                        break;
#endif


                                case IPV6_VLAN_PCP:
                                        if (OPTBIT2(INP_2PCP_SET)) {
                                                optval = (inp->inp_flags2 &
                                                            INP_2PCP_MASK) >>
                                                            INP_2PCP_SHIFT;
                                        } else {
                                                optval = -1;
                                        }
                                        break;
                                }

                                if (error)
                                        break;
                                error = sooptcopyout(sopt, &optval,
                                        sizeof optval);
                                break;

                        case IPV6_PATHMTU:
                        {
                                u_long pmtu = 0;
                                struct ip6_mtuinfo mtuinfo;
                                struct in6_addr addr;

                                if (!(so->so_state & SS_ISCONNECTED))
                                        return (ENOTCONN);
                                /*
                                 * XXX: we dot not consider the case of source
                                 * routing, or optional information to specify
                                 * the outgoing interface.
                                 * Copy faddr out of inp to avoid holding lock
                                 * on inp during route lookup.
                                 */
                                INP_RLOCK(inp);
                                bcopy(&inp->in6p_faddr, &addr, sizeof(addr));
                                INP_RUNLOCK(inp);
                                error = ip6_getpmtu_ctl(so->so_fibnum,
                                    &addr, &pmtu);
                                if (error)
                                        break;
                                if (pmtu > IPV6_MAXPACKET)
                                        pmtu = IPV6_MAXPACKET;

                                bzero(&mtuinfo, sizeof(mtuinfo));
                                mtuinfo.ip6m_mtu = (u_int32_t)pmtu;
                                optdata = (void *)&mtuinfo;
                                optdatalen = sizeof(mtuinfo);
                                error = sooptcopyout(sopt, optdata,
                                    optdatalen);
                                break;
                        }

                        case IPV6_2292PKTINFO:
                        case IPV6_2292HOPLIMIT:
                        case IPV6_2292HOPOPTS:
                        case IPV6_2292RTHDR:
                        case IPV6_2292DSTOPTS:
                                switch (optname) {
                                case IPV6_2292PKTINFO:
                                        optval = OPTBIT(IN6P_PKTINFO);
                                        break;
                                case IPV6_2292HOPLIMIT:
                                        optval = OPTBIT(IN6P_HOPLIMIT);
                                        break;
                                case IPV6_2292HOPOPTS:
                                        optval = OPTBIT(IN6P_HOPOPTS);
                                        break;
                                case IPV6_2292RTHDR:
                                        optval = OPTBIT(IN6P_RTHDR);
                                        break;
                                case IPV6_2292DSTOPTS:
                                        optval = OPTBIT(IN6P_DSTOPTS|IN6P_RTHDRDSTOPTS);
                                        break;
                                }
                                error = sooptcopyout(sopt, &optval,
                                    sizeof optval);
                                break;
                        case IPV6_PKTINFO:
                        case IPV6_HOPOPTS:
                        case IPV6_RTHDR:
                        case IPV6_DSTOPTS:
                        case IPV6_RTHDRDSTOPTS:
                        case IPV6_NEXTHOP:
                        case IPV6_TCLASS:
                        case IPV6_DONTFRAG:
                        case IPV6_USE_MIN_MTU:
                        case IPV6_PREFER_TEMPADDR:
                                error = ip6_getpcbopt(inp, optname, sopt);
                                break;

                        case IPV6_MULTICAST_IF:
                        case IPV6_MULTICAST_HOPS:
                        case IPV6_MULTICAST_LOOP:
                        case IPV6_MSFILTER:
                                error = ip6_getmoptions(inp, sopt);
                                break;

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
                        case IPV6_IPSEC_POLICY:
                                if (IPSEC_ENABLED(ipv6)) {
                                        error = IPSEC_PCBCTL(ipv6, inp, sopt);
                                        break;
                                }
                                /* FALLTHROUGH */
#endif /* IPSEC */
                        default:
                                error = ENOPROTOOPT;
                                break;
                        }
                        break;
                }
        }
        return (error);
}

int
ip6_raw_ctloutput(struct socket *so, struct sockopt *sopt)
{
        int error = 0, optval, optlen;
        const int icmp6off = offsetof(struct icmp6_hdr, icmp6_cksum);
        struct inpcb *inp = sotoinpcb(so);
        int level, op, optname;

        level = sopt->sopt_level;
        op = sopt->sopt_dir;
        optname = sopt->sopt_name;
        optlen = sopt->sopt_valsize;

        if (level != IPPROTO_IPV6) {
                return (EINVAL);
        }

        switch (optname) {
        case IPV6_CHECKSUM:
                /*
                 * For ICMPv6 sockets, no modification allowed for checksum
                 * offset, permit "no change" values to help existing apps.
                 *
                 * RFC3542 says: "An attempt to set IPV6_CHECKSUM
                 * for an ICMPv6 socket will fail."
                 * The current behavior does not meet RFC3542.
                 */
                switch (op) {
                case SOPT_SET:
                        if (optlen != sizeof(int)) {
                                error = EINVAL;
                                break;
                        }
                        error = sooptcopyin(sopt, &optval, sizeof(optval),
                                            sizeof(optval));
                        if (error)
                                break;
                        if (optval < -1 || (optval % 2) != 0) {
                                /*
                                 * The API assumes non-negative even offset
                                 * values or -1 as a special value.
                                 */
                                error = EINVAL;
                        } else if (inp->inp_ip_p == IPPROTO_ICMPV6) {
                                if (optval != icmp6off)
                                        error = EINVAL;
                        } else
                                inp->in6p_cksum = optval;
                        break;

                case SOPT_GET:
                        if (inp->inp_ip_p == IPPROTO_ICMPV6)
                                optval = icmp6off;
                        else
                                optval = inp->in6p_cksum;

                        error = sooptcopyout(sopt, &optval, sizeof(optval));
                        break;

                default:
                        error = EINVAL;
                        break;
                }
                break;

        default:
                error = ENOPROTOOPT;
                break;
        }

        return (error);
}

/*
 * Set up IP6 options in pcb for insertion in output packets or
 * specifying behavior of outgoing packets.
 */
static int
ip6_pcbopts(struct ip6_pktopts **pktopt, struct mbuf *m,
    struct socket *so, struct sockopt *sopt)
{
        struct ip6_pktopts *opt = *pktopt;
        int error = 0;
        struct thread *td = sopt->sopt_td;
        struct epoch_tracker et;

        /* turn off any old options. */
        if (opt) {
#ifdef DIAGNOSTIC
                if (opt->ip6po_pktinfo || opt->ip6po_nexthop ||
                    opt->ip6po_hbh || opt->ip6po_dest1 || opt->ip6po_dest2 ||
                    opt->ip6po_rhinfo.ip6po_rhi_rthdr)
                        printf("ip6_pcbopts: all specified options are cleared.\n");
#endif
                ip6_clearpktopts(opt, -1);
        } else {
                opt = malloc(sizeof(*opt), M_IP6OPT, M_NOWAIT);
                if (opt == NULL)
                        return (ENOMEM);
        }
        *pktopt = NULL;

        if (!m || m->m_len == 0) {
                /*
                 * Only turning off any previous options, regardless of
                 * whether the opt is just created or given.
                 */
                free(opt, M_IP6OPT);
                return (0);
        }

        /*  set options specified by user. */
        NET_EPOCH_ENTER(et);
        if ((error = ip6_setpktopts(m, opt, NULL, (td != NULL) ?
            td->td_ucred : NULL, so->so_proto->pr_protocol)) != 0) {
                ip6_clearpktopts(opt, -1); /* XXX: discard all options */
                free(opt, M_IP6OPT);
                NET_EPOCH_EXIT(et);
                return (error);
        }
        NET_EPOCH_EXIT(et);
        *pktopt = opt;
        return (0);
}

/*
 * initialize ip6_pktopts.  beware that there are non-zero default values in
 * the struct.
 */
void
ip6_initpktopts(struct ip6_pktopts *opt)
{

        bzero(opt, sizeof(*opt));
        opt->ip6po_hlim = -1;   /* -1 means default hop limit */
        opt->ip6po_tclass = -1; /* -1 means default traffic class */
        opt->ip6po_minmtu = IP6PO_MINMTU_MCASTONLY;
        opt->ip6po_prefer_tempaddr = IP6PO_TEMPADDR_SYSTEM;
}

static int
ip6_pcbopt(int optname, u_char *buf, int len, struct ip6_pktopts **pktopt,
    struct ucred *cred, int uproto)
{
        struct epoch_tracker et;
        struct ip6_pktopts *opt;
        int ret;

        if (*pktopt == NULL) {
                *pktopt = malloc(sizeof(struct ip6_pktopts), M_IP6OPT,
                    M_NOWAIT);
                if (*pktopt == NULL)
                        return (ENOBUFS);
                ip6_initpktopts(*pktopt);
        }
        opt = *pktopt;

        NET_EPOCH_ENTER(et);
        ret = ip6_setpktopt(optname, buf, len, opt, cred, 1, 0, uproto);
        NET_EPOCH_EXIT(et);

        return (ret);
}

#define GET_PKTOPT_VAR(field, lenexpr) do {                             \
        if (pktopt && pktopt->field) {                                  \
                INP_RUNLOCK(inp);                                       \
                optdata = malloc(sopt->sopt_valsize, M_TEMP, M_WAITOK); \
                malloc_optdata = true;                                  \
                INP_RLOCK(inp);                                         \
                if (inp->inp_flags & INP_DROPPED) {                     \
                        INP_RUNLOCK(inp);                               \
                        free(optdata, M_TEMP);                          \
                        return (ECONNRESET);                            \
                }                                                       \
                pktopt = inp->in6p_outputopts;                          \
                if (pktopt && pktopt->field) {                          \
                        optdatalen = min(lenexpr, sopt->sopt_valsize);  \
                        bcopy(pktopt->field, optdata, optdatalen);      \
                } else {                                                \
                        free(optdata, M_TEMP);                          \
                        optdata = NULL;                                 \
                        malloc_optdata = false;                         \
                }                                                       \
        }                                                               \
} while(0)

#define GET_PKTOPT_EXT_HDR(field) GET_PKTOPT_VAR(field,                 \
        (((struct ip6_ext *)pktopt->field)->ip6e_len + 1) << 3)

#define GET_PKTOPT_SOCKADDR(field) GET_PKTOPT_VAR(field,                \
        pktopt->field->sa_len)

static int
ip6_getpcbopt(struct inpcb *inp, int optname, struct sockopt *sopt)
{
        void *optdata = NULL;
        bool malloc_optdata = false;
        int optdatalen = 0;
        int error = 0;
        struct in6_pktinfo null_pktinfo;
        int deftclass = 0, on;
        int defminmtu = IP6PO_MINMTU_MCASTONLY;
        int defpreftemp = IP6PO_TEMPADDR_SYSTEM;
        struct ip6_pktopts *pktopt;

        INP_RLOCK(inp);
        pktopt = inp->in6p_outputopts;

        switch (optname) {
        case IPV6_PKTINFO:
                optdata = (void *)&null_pktinfo;
                if (pktopt && pktopt->ip6po_pktinfo) {
                        bcopy(pktopt->ip6po_pktinfo, &null_pktinfo,
                            sizeof(null_pktinfo));
                        in6_clearscope(&null_pktinfo.ipi6_addr);
                } else {
                        /* XXX: we don't have to do this every time... */
                        bzero(&null_pktinfo, sizeof(null_pktinfo));
                }
                optdatalen = sizeof(struct in6_pktinfo);
                break;
        case IPV6_TCLASS:
                if (pktopt && pktopt->ip6po_tclass >= 0)
                        deftclass = pktopt->ip6po_tclass;
                optdata = (void *)&deftclass;
                optdatalen = sizeof(int);
                break;
        case IPV6_HOPOPTS:
                GET_PKTOPT_EXT_HDR(ip6po_hbh);
                break;
        case IPV6_RTHDR:
                GET_PKTOPT_EXT_HDR(ip6po_rthdr);
                break;
        case IPV6_RTHDRDSTOPTS:
                GET_PKTOPT_EXT_HDR(ip6po_dest1);
                break;
        case IPV6_DSTOPTS:
                GET_PKTOPT_EXT_HDR(ip6po_dest2);
                break;
        case IPV6_NEXTHOP:
                GET_PKTOPT_SOCKADDR(ip6po_nexthop);
                break;
        case IPV6_USE_MIN_MTU:
                if (pktopt)
                        defminmtu = pktopt->ip6po_minmtu;
                optdata = (void *)&defminmtu;
                optdatalen = sizeof(int);
                break;
        case IPV6_DONTFRAG:
                if (pktopt && ((pktopt->ip6po_flags) & IP6PO_DONTFRAG))
                        on = 1;
                else
                        on = 0;
                optdata = (void *)&on;
                optdatalen = sizeof(on);
                break;
        case IPV6_PREFER_TEMPADDR:
                if (pktopt)
                        defpreftemp = pktopt->ip6po_prefer_tempaddr;
                optdata = (void *)&defpreftemp;
                optdatalen = sizeof(int);
                break;
        default:                /* should not happen */
#ifdef DIAGNOSTIC
                panic("ip6_getpcbopt: unexpected option\n");
#endif
                INP_RUNLOCK(inp);
                return (ENOPROTOOPT);
        }
        INP_RUNLOCK(inp);

        error = sooptcopyout(sopt, optdata, optdatalen);
        if (malloc_optdata)
                free(optdata, M_TEMP);

        return (error);
}

void
ip6_clearpktopts(struct ip6_pktopts *pktopt, int optname)
{
        if (pktopt == NULL)
                return;

        if (optname == -1 || optname == IPV6_PKTINFO) {
                if (pktopt->ip6po_pktinfo)
                        free(pktopt->ip6po_pktinfo, M_IP6OPT);
                pktopt->ip6po_pktinfo = NULL;
        }
        if (optname == -1 || optname == IPV6_HOPLIMIT) {
                pktopt->ip6po_hlim = -1;
                pktopt->ip6po_valid &= ~IP6PO_VALID_HLIM;
        }
        if (optname == -1 || optname == IPV6_TCLASS) {
                pktopt->ip6po_tclass = -1;
                pktopt->ip6po_valid &= ~IP6PO_VALID_TC;
        }
        if (optname == -1 || optname == IPV6_NEXTHOP) {
                if (pktopt->ip6po_nextroute.ro_nh) {
                        NH_FREE(pktopt->ip6po_nextroute.ro_nh);
                        pktopt->ip6po_nextroute.ro_nh = NULL;
                }
                if (pktopt->ip6po_nexthop)
                        free(pktopt->ip6po_nexthop, M_IP6OPT);
                pktopt->ip6po_nexthop = NULL;
                pktopt->ip6po_valid &= ~IP6PO_VALID_NHINFO;
        }
        if (optname == -1 || optname == IPV6_HOPOPTS) {
                if (pktopt->ip6po_hbh)
                        free(pktopt->ip6po_hbh, M_IP6OPT);
                pktopt->ip6po_hbh = NULL;
                pktopt->ip6po_valid &= ~IP6PO_VALID_HBH;
        }
        if (optname == -1 || optname == IPV6_RTHDRDSTOPTS) {
                if (pktopt->ip6po_dest1)
                        free(pktopt->ip6po_dest1, M_IP6OPT);
                pktopt->ip6po_dest1 = NULL;
                pktopt->ip6po_valid &= ~IP6PO_VALID_DEST1;
        }
        if (optname == -1 || optname == IPV6_RTHDR) {
                if (pktopt->ip6po_rhinfo.ip6po_rhi_rthdr)
                        free(pktopt->ip6po_rhinfo.ip6po_rhi_rthdr, M_IP6OPT);
                pktopt->ip6po_rhinfo.ip6po_rhi_rthdr = NULL;
                if (pktopt->ip6po_route.ro_nh) {
                        NH_FREE(pktopt->ip6po_route.ro_nh);
                        pktopt->ip6po_route.ro_nh = NULL;
                }
                pktopt->ip6po_valid &= ~IP6PO_VALID_RHINFO;
        }
        if (optname == -1 || optname == IPV6_DSTOPTS) {
                if (pktopt->ip6po_dest2)
                        free(pktopt->ip6po_dest2, M_IP6OPT);
                pktopt->ip6po_dest2 = NULL;
                pktopt->ip6po_valid &= ~IP6PO_VALID_DEST2;
        }
}

#define PKTOPT_EXTHDRCPY(type) \
do {\
        if (src->type) {\
                int hlen = (((struct ip6_ext *)src->type)->ip6e_len + 1) << 3;\
                dst->type = malloc(hlen, M_IP6OPT, canwait);\
                if (dst->type == NULL)\
                        goto bad;\
                bcopy(src->type, dst->type, hlen);\
        }\
} while (/*CONSTCOND*/ 0)

static int
copypktopts(struct ip6_pktopts *dst, struct ip6_pktopts *src, int canwait)
{
        if (dst == NULL || src == NULL)  {
                printf("ip6_clearpktopts: invalid argument\n");
                return (EINVAL);
        }

        dst->ip6po_hlim = src->ip6po_hlim;
        dst->ip6po_tclass = src->ip6po_tclass;
        dst->ip6po_flags = src->ip6po_flags;
        dst->ip6po_minmtu = src->ip6po_minmtu;
        dst->ip6po_prefer_tempaddr = src->ip6po_prefer_tempaddr;
        if (src->ip6po_pktinfo) {
                dst->ip6po_pktinfo = malloc(sizeof(*dst->ip6po_pktinfo),
                    M_IP6OPT, canwait);
                if (dst->ip6po_pktinfo == NULL)
                        goto bad;
                *dst->ip6po_pktinfo = *src->ip6po_pktinfo;
        }
        if (src->ip6po_nexthop) {
                dst->ip6po_nexthop = malloc(src->ip6po_nexthop->sa_len,
                    M_IP6OPT, canwait);
                if (dst->ip6po_nexthop == NULL)
                        goto bad;
                bcopy(src->ip6po_nexthop, dst->ip6po_nexthop,
                    src->ip6po_nexthop->sa_len);
        }
        PKTOPT_EXTHDRCPY(ip6po_hbh);
        PKTOPT_EXTHDRCPY(ip6po_dest1);
        PKTOPT_EXTHDRCPY(ip6po_dest2);
        PKTOPT_EXTHDRCPY(ip6po_rthdr); /* not copy the cached route */
        dst->ip6po_valid = src->ip6po_valid;
        return (0);

  bad:
        ip6_clearpktopts(dst, -1);
        return (ENOBUFS);
}
#undef PKTOPT_EXTHDRCPY

struct ip6_pktopts *
ip6_copypktopts(struct ip6_pktopts *src, int canwait)
{
        int error;
        struct ip6_pktopts *dst;

        dst = malloc(sizeof(*dst), M_IP6OPT, canwait);
        if (dst == NULL)
                return (NULL);
        ip6_initpktopts(dst);

        if ((error = copypktopts(dst, src, canwait)) != 0) {
                free(dst, M_IP6OPT);
                return (NULL);
        }

        return (dst);
}

void
ip6_freepcbopts(struct ip6_pktopts *pktopt)
{
        if (pktopt == NULL)
                return;

        ip6_clearpktopts(pktopt, -1);

        free(pktopt, M_IP6OPT);
}

/*
 * Set IPv6 outgoing packet options based on advanced API.
 */
int
ip6_setpktopts(struct mbuf *control, struct ip6_pktopts *opt,
    struct ip6_pktopts *stickyopt, struct ucred *cred, int uproto)
{
        struct cmsghdr *cm = NULL;

        if (control == NULL || opt == NULL)
                return (EINVAL);

        /*
         * ip6_setpktopt can call ifnet_byindex(), so it's imperative that we
         * are in the network epoch here.
         */
        NET_EPOCH_ASSERT();

        ip6_initpktopts(opt);
        if (stickyopt) {
                int error;

                /*
                 * If stickyopt is provided, make a local copy of the options
                 * for this particular packet, then override them by ancillary
                 * objects.
                 * XXX: copypktopts() does not copy the cached route to a next
                 * hop (if any).  This is not very good in terms of efficiency,
                 * but we can allow this since this option should be rarely
                 * used.
                 */
                if ((error = copypktopts(opt, stickyopt, M_NOWAIT)) != 0)
                        return (error);
        }

        /*
         * XXX: Currently, we assume all the optional information is stored
         * in a single mbuf.
         */
        if (control->m_next)
                return (EINVAL);

        for (; control->m_len > 0; control->m_data += CMSG_ALIGN(cm->cmsg_len),
            control->m_len -= CMSG_ALIGN(cm->cmsg_len)) {
                int error;

                if (control->m_len < CMSG_LEN(0))
                        return (EINVAL);

                cm = mtod(control, struct cmsghdr *);
                if (cm->cmsg_len == 0 || cm->cmsg_len > control->m_len)
                        return (EINVAL);
                if (cm->cmsg_level != IPPROTO_IPV6)
                        continue;

                error = ip6_setpktopt(cm->cmsg_type, CMSG_DATA(cm),
                    cm->cmsg_len - CMSG_LEN(0), opt, cred, 0, 1, uproto);
                if (error)
                        return (error);
        }

        return (0);
}

/*
 * Set a particular packet option, as a sticky option or an ancillary data
 * item.  "len" can be 0 only when it's a sticky option.
 * We have 4 cases of combination of "sticky" and "cmsg":
 * "sticky=0, cmsg=0": impossible
 * "sticky=0, cmsg=1": RFC2292 or RFC3542 ancillary data
 * "sticky=1, cmsg=0": RFC3542 socket option
 * "sticky=1, cmsg=1": RFC2292 socket option
 */
static int
ip6_setpktopt(int optname, u_char *buf, int len, struct ip6_pktopts *opt,
    struct ucred *cred, int sticky, int cmsg, int uproto)
{
        int minmtupolicy, preftemp;
        int error;

        NET_EPOCH_ASSERT();

        if (!sticky && !cmsg) {
#ifdef DIAGNOSTIC
                printf("ip6_setpktopt: impossible case\n");
#endif
                return (EINVAL);
        }

        /*
         * IPV6_2292xxx is for backward compatibility to RFC2292, and should
         * not be specified in the context of RFC3542.  Conversely,
         * RFC3542 types should not be specified in the context of RFC2292.
         */
        if (!cmsg) {
                switch (optname) {
                case IPV6_2292PKTINFO:
                case IPV6_2292HOPLIMIT:
                case IPV6_2292NEXTHOP:
                case IPV6_2292HOPOPTS:
                case IPV6_2292DSTOPTS:
                case IPV6_2292RTHDR:
                case IPV6_2292PKTOPTIONS:
                        return (ENOPROTOOPT);
                }
        }
        if (sticky && cmsg) {
                switch (optname) {
                case IPV6_PKTINFO:
                case IPV6_HOPLIMIT:
                case IPV6_NEXTHOP:
                case IPV6_HOPOPTS:
                case IPV6_DSTOPTS:
                case IPV6_RTHDRDSTOPTS:
                case IPV6_RTHDR:
                case IPV6_USE_MIN_MTU:
                case IPV6_DONTFRAG:
                case IPV6_TCLASS:
                case IPV6_PREFER_TEMPADDR: /* XXX: not an RFC3542 option */
                        return (ENOPROTOOPT);
                }
        }

        switch (optname) {
        case IPV6_2292PKTINFO:
        case IPV6_PKTINFO:
        {
                struct ifnet *ifp = NULL;
                struct in6_pktinfo *pktinfo;

                if (len != sizeof(struct in6_pktinfo))
                        return (EINVAL);

                pktinfo = (struct in6_pktinfo *)buf;

                /*
                 * An application can clear any sticky IPV6_PKTINFO option by
                 * doing a "regular" setsockopt with ipi6_addr being
                 * in6addr_any and ipi6_ifindex being zero.
                 * [RFC 3542, Section 6]
                 */
                if (optname == IPV6_PKTINFO && opt->ip6po_pktinfo &&
                    pktinfo->ipi6_ifindex == 0 &&
                    IN6_IS_ADDR_UNSPECIFIED(&pktinfo->ipi6_addr)) {
                        ip6_clearpktopts(opt, optname);
                        break;
                }

                if (uproto == IPPROTO_TCP && optname == IPV6_PKTINFO &&
                    sticky && !IN6_IS_ADDR_UNSPECIFIED(&pktinfo->ipi6_addr)) {
                        return (EINVAL);
                }
                if (IN6_IS_ADDR_MULTICAST(&pktinfo->ipi6_addr))
                        return (EINVAL);
                /* validate the interface index if specified. */
                if (pktinfo->ipi6_ifindex) {
                        ifp = ifnet_byindex(pktinfo->ipi6_ifindex);
                        if (ifp == NULL)
                                return (ENXIO);
                }
                if (ifp != NULL && (ifp->if_inet6 == NULL ||
                    (ifp->if_inet6->nd_flags & ND6_IFF_IFDISABLED) != 0))
                        return (ENETDOWN);

                if (ifp != NULL &&
                    !IN6_IS_ADDR_UNSPECIFIED(&pktinfo->ipi6_addr)) {
                        struct in6_ifaddr *ia;

                        in6_setscope(&pktinfo->ipi6_addr, ifp, NULL);
                        ia = in6ifa_ifpwithaddr(ifp, &pktinfo->ipi6_addr);
                        if (ia == NULL)
                                return (EADDRNOTAVAIL);
                        ifa_free(&ia->ia_ifa);
                }
                /*
                 * We store the address anyway, and let in6_selectsrc()
                 * validate the specified address.  This is because ipi6_addr
                 * may not have enough information about its scope zone, and
                 * we may need additional information (such as outgoing
                 * interface or the scope zone of a destination address) to
                 * disambiguate the scope.
                 * XXX: the delay of the validation may confuse the
                 * application when it is used as a sticky option.
                 */
                if (opt->ip6po_pktinfo == NULL) {
                        opt->ip6po_pktinfo = malloc(sizeof(*pktinfo),
                            M_IP6OPT, M_NOWAIT);
                        if (opt->ip6po_pktinfo == NULL)
                                return (ENOBUFS);
                }
                bcopy(pktinfo, opt->ip6po_pktinfo, sizeof(*pktinfo));
                opt->ip6po_valid |= IP6PO_VALID_PKTINFO;
                break;
        }

        case IPV6_2292HOPLIMIT:
        case IPV6_HOPLIMIT:
        {
                int *hlimp;

                /*
                 * RFC 3542 deprecated the usage of sticky IPV6_HOPLIMIT
                 * to simplify the ordering among hoplimit options.
                 */
                if (optname == IPV6_HOPLIMIT && sticky)
                        return (ENOPROTOOPT);

                if (len != sizeof(int))
                        return (EINVAL);
                hlimp = (int *)buf;
                if (*hlimp < -1 || *hlimp > 255)
                        return (EINVAL);

                opt->ip6po_hlim = *hlimp;
                opt->ip6po_valid |= IP6PO_VALID_HLIM;
                break;
        }

        case IPV6_TCLASS:
        {
                int tclass;

                if (len != sizeof(int))
                        return (EINVAL);
                tclass = *(int *)buf;
                if (tclass < -1 || tclass > 255)
                        return (EINVAL);

                opt->ip6po_tclass = tclass;
                opt->ip6po_valid |= IP6PO_VALID_TC;
                break;
        }

        case IPV6_2292NEXTHOP:
        case IPV6_NEXTHOP:
                if (cred != NULL) {
                        error = priv_check_cred(cred, PRIV_NETINET_SETHDROPTS);
                        if (error)
                                return (error);
                }

                if (len == 0) { /* just remove the option */
                        ip6_clearpktopts(opt, IPV6_NEXTHOP);
                        break;
                }

                /* check if cmsg_len is large enough for sa_len */
                if (len < sizeof(struct sockaddr) || len < *buf)
                        return (EINVAL);

                switch (((struct sockaddr *)buf)->sa_family) {
                case AF_INET6:
                {
                        struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)buf;
                        int error;

                        if (sa6->sin6_len != sizeof(struct sockaddr_in6))
                                return (EINVAL);

                        if (IN6_IS_ADDR_UNSPECIFIED(&sa6->sin6_addr) ||
                            IN6_IS_ADDR_MULTICAST(&sa6->sin6_addr)) {
                                return (EINVAL);
                        }
                        if ((error = sa6_embedscope(sa6, V_ip6_use_defzone))
                            != 0) {
                                return (error);
                        }
                        break;
                }
                case AF_LINK:   /* should eventually be supported */
                default:
                        return (EAFNOSUPPORT);
                }

                /* turn off the previous option, then set the new option. */
                ip6_clearpktopts(opt, IPV6_NEXTHOP);
                opt->ip6po_nexthop = malloc(*buf, M_IP6OPT, M_NOWAIT);
                if (opt->ip6po_nexthop == NULL)
                        return (ENOBUFS);
                bcopy(buf, opt->ip6po_nexthop, *buf);
                opt->ip6po_valid |= IP6PO_VALID_NHINFO;
                break;

        case IPV6_2292HOPOPTS:
        case IPV6_HOPOPTS:
        {
                struct ip6_hbh *hbh;
                int hbhlen;

                /*
                 * XXX: We don't allow a non-privileged user to set ANY HbH
                 * options, since per-option restriction has too much
                 * overhead.
                 */
                if (cred != NULL) {
                        error = priv_check_cred(cred, PRIV_NETINET_SETHDROPTS);
                        if (error)
                                return (error);
                }

                if (len == 0) {
                        ip6_clearpktopts(opt, IPV6_HOPOPTS);
                        break;  /* just remove the option */
                }

                /* message length validation */
                if (len < sizeof(struct ip6_hbh))
                        return (EINVAL);
                hbh = (struct ip6_hbh *)buf;
                hbhlen = (hbh->ip6h_len + 1) << 3;
                if (len != hbhlen)
                        return (EINVAL);

                /* turn off the previous option, then set the new option. */
                ip6_clearpktopts(opt, IPV6_HOPOPTS);
                opt->ip6po_hbh = malloc(hbhlen, M_IP6OPT, M_NOWAIT);
                if (opt->ip6po_hbh == NULL)
                        return (ENOBUFS);
                bcopy(hbh, opt->ip6po_hbh, hbhlen);
                opt->ip6po_valid |= IP6PO_VALID_HBH;

                break;
        }

        case IPV6_2292DSTOPTS:
        case IPV6_DSTOPTS:
        case IPV6_RTHDRDSTOPTS:
        {
                struct ip6_dest *dest, **newdest = NULL;
                int destlen;

                if (cred != NULL) { /* XXX: see the comment for IPV6_HOPOPTS */
                        error = priv_check_cred(cred, PRIV_NETINET_SETHDROPTS);
                        if (error)
                                return (error);
                }

                if (len == 0) {
                        ip6_clearpktopts(opt, optname);
                        break;  /* just remove the option */
                }

                /* message length validation */
                if (len < sizeof(struct ip6_dest))
                        return (EINVAL);
                dest = (struct ip6_dest *)buf;
                destlen = (dest->ip6d_len + 1) << 3;
                if (len != destlen)
                        return (EINVAL);

                /*
                 * Determine the position that the destination options header
                 * should be inserted; before or after the routing header.
                 */
                switch (optname) {
                case IPV6_2292DSTOPTS:
                        /*
                         * The old advacned API is ambiguous on this point.
                         * Our approach is to determine the position based
                         * according to the existence of a routing header.
                         * Note, however, that this depends on the order of the
                         * extension headers in the ancillary data; the 1st
                         * part of the destination options header must appear
                         * before the routing header in the ancillary data,
                         * too.
                         * RFC3542 solved the ambiguity by introducing
                         * separate ancillary data or option types.
                         */
                        if (opt->ip6po_rthdr == NULL)
                                newdest = &opt->ip6po_dest1;
                        else
                                newdest = &opt->ip6po_dest2;
                        break;
                case IPV6_RTHDRDSTOPTS:
                        newdest = &opt->ip6po_dest1;
                        break;
                case IPV6_DSTOPTS:
                        newdest = &opt->ip6po_dest2;
                        break;
                }

                /* turn off the previous option, then set the new option. */
                ip6_clearpktopts(opt, optname);
                *newdest = malloc(destlen, M_IP6OPT, M_NOWAIT);
                if (*newdest == NULL)
                        return (ENOBUFS);
                bcopy(dest, *newdest, destlen);
                if (newdest == &opt->ip6po_dest1)
                        opt->ip6po_valid |= IP6PO_VALID_DEST1;
                else
                        opt->ip6po_valid |= IP6PO_VALID_DEST2;

                break;
        }

        case IPV6_2292RTHDR:
        case IPV6_RTHDR:
        {
                struct ip6_rthdr *rth;
                int rthlen;

                if (len == 0) {
                        ip6_clearpktopts(opt, IPV6_RTHDR);
                        break;  /* just remove the option */
                }

                /* message length validation */
                if (len < sizeof(struct ip6_rthdr))
                        return (EINVAL);
                rth = (struct ip6_rthdr *)buf;
                rthlen = (rth->ip6r_len + 1) << 3;
                if (len != rthlen)
                        return (EINVAL);

                switch (rth->ip6r_type) {
                case IPV6_RTHDR_TYPE_0:
                        if (rth->ip6r_len == 0) /* must contain one addr */
                                return (EINVAL);
                        if (rth->ip6r_len % 2) /* length must be even */
                                return (EINVAL);
                        if (rth->ip6r_len / 2 != rth->ip6r_segleft)
                                return (EINVAL);
                        break;
                default:
                        return (EINVAL);        /* not supported */
                }

                /* turn off the previous option */
                ip6_clearpktopts(opt, IPV6_RTHDR);
                opt->ip6po_rthdr = malloc(rthlen, M_IP6OPT, M_NOWAIT);
                if (opt->ip6po_rthdr == NULL)
                        return (ENOBUFS);
                bcopy(rth, opt->ip6po_rthdr, rthlen);
                opt->ip6po_valid |= IP6PO_VALID_RHINFO;

                break;
        }

        case IPV6_USE_MIN_MTU:
                if (len != sizeof(int))
                        return (EINVAL);
                minmtupolicy = *(int *)buf;
                if (minmtupolicy != IP6PO_MINMTU_MCASTONLY &&
                    minmtupolicy != IP6PO_MINMTU_DISABLE &&
                    minmtupolicy != IP6PO_MINMTU_ALL) {
                        return (EINVAL);
                }
                opt->ip6po_minmtu = minmtupolicy;
                break;

        case IPV6_DONTFRAG:
                if (len != sizeof(int))
                        return (EINVAL);

                if (uproto == IPPROTO_TCP || *(int *)buf == 0) {
                        /*
                         * we ignore this option for TCP sockets.
                         * (RFC3542 leaves this case unspecified.)
                         */
                        opt->ip6po_flags &= ~IP6PO_DONTFRAG;
                } else
                        opt->ip6po_flags |= IP6PO_DONTFRAG;
                break;

        case IPV6_PREFER_TEMPADDR:
                if (len != sizeof(int))
                        return (EINVAL);
                preftemp = *(int *)buf;
                if (preftemp != IP6PO_TEMPADDR_SYSTEM &&
                    preftemp != IP6PO_TEMPADDR_NOTPREFER &&
                    preftemp != IP6PO_TEMPADDR_PREFER) {
                        return (EINVAL);
                }
                opt->ip6po_prefer_tempaddr = preftemp;
                break;

        default:
                return (ENOPROTOOPT);
        } /* end of switch */

        return (0);
}

/*
 * Routine called from ip6_output() to loop back a copy of an IP6 multicast
 * packet to the input queue of a specified interface.  Note that this
 * calls the output routine of the loopback "driver", but with an interface
 * pointer that might NOT be &loif -- easier than replicating that code here.
 */
void
ip6_mloopback(struct ifnet *ifp, struct mbuf *m)
{
        struct mbuf *copym;
        struct ip6_hdr *ip6;

        copym = m_copym(m, 0, M_COPYALL, M_NOWAIT);
        if (copym == NULL)
                return;

        /*
         * Make sure to deep-copy IPv6 header portion in case the data
         * is in an mbuf cluster, so that we can safely override the IPv6
         * header portion later.
         */
        if (!M_WRITABLE(copym) ||
            copym->m_len < sizeof(struct ip6_hdr)) {
                copym = m_pullup(copym, sizeof(struct ip6_hdr));
                if (copym == NULL)
                        return;
        }
        ip6 = mtod(copym, struct ip6_hdr *);
        /*
         * clear embedded scope identifiers if necessary.
         * in6_clearscope will touch the addresses only when necessary.
         */
        in6_clearscope(&ip6->ip6_src);
        in6_clearscope(&ip6->ip6_dst);
        if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
                copym->m_pkthdr.csum_flags |= CSUM_DATA_VALID_IPV6 |
                    CSUM_PSEUDO_HDR;
                copym->m_pkthdr.csum_data = 0xffff;
        }
        if_simloop(ifp, copym, AF_INET6, 0);
}

/*
 * Chop IPv6 header off from the payload.
 */
static int
ip6_splithdr(struct mbuf *m, struct ip6_exthdrs *exthdrs)
{
        struct mbuf *mh;
        struct ip6_hdr *ip6;

        ip6 = mtod(m, struct ip6_hdr *);
        if (m->m_len > sizeof(*ip6)) {
                mh = m_gethdr(M_NOWAIT, MT_DATA);
                if (mh == NULL) {
                        m_freem(m);
                        return ENOBUFS;
                }
                m_move_pkthdr(mh, m);
                M_ALIGN(mh, sizeof(*ip6));
                m->m_len -= sizeof(*ip6);
                m->m_data += sizeof(*ip6);
                mh->m_next = m;
                m = mh;
                m->m_len = sizeof(*ip6);
                bcopy((caddr_t)ip6, mtod(m, caddr_t), sizeof(*ip6));
        }
        exthdrs->ip6e_ip6 = m;
        return 0;
}

/*
 * Compute IPv6 extension header length.
 */
int
ip6_optlen(struct inpcb *inp)
{
        int len;

        if (!inp->in6p_outputopts)
                return 0;

        len = 0;
#define elen(x) \
    (((struct ip6_ext *)(x)) ? (((struct ip6_ext *)(x))->ip6e_len + 1) << 3 : 0)

        len += elen(inp->in6p_outputopts->ip6po_hbh);
        if (inp->in6p_outputopts->ip6po_rthdr)
                /* dest1 is valid with rthdr only */
                len += elen(inp->in6p_outputopts->ip6po_dest1);
        len += elen(inp->in6p_outputopts->ip6po_rthdr);
        len += elen(inp->in6p_outputopts->ip6po_dest2);
        return len;
#undef elen
}