/*-
 * 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_input.c,v 1.259 2002/01/21 04:58:09 jinmei Exp $
 */

/*-
 * Copyright (c) 1982, 1986, 1988, 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_rss.h"
#include "opt_sctp.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/hhook.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/sdt.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <sys/eventhandler.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_types.h>
#include <net/if_private.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/rss_config.h>
#include <net/pfil.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <netinet/ip_var.h>
#include <netinet/in_systm.h>
#include <net/if_llatbl.h>
#ifdef INET
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#endif /* INET */
#include <netinet/ip6.h>
#include <netinet6/in6_var.h>
#include <netinet6/ip6_var.h>
#include <netinet/ip_encap.h>
#include <netinet/in_pcb.h>
#include <netinet/icmp6.h>
#include <netinet6/scope6_var.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/mld6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/in6_rss.h>
#include <netinet6/ip6_mroute.h>
#ifdef SCTP
#include <netinet/sctp_pcb.h>
#include <netinet6/sctp6_var.h>
#endif

#include <netipsec/ipsec_support.h>

ip6proto_input_t        *ip6_protox[IPPROTO_MAX] = {
                            [0 ... IPPROTO_MAX - 1] = rip6_input };
ip6proto_ctlinput_t     *ip6_ctlprotox[IPPROTO_MAX] = {
                            [0 ... IPPROTO_MAX - 1] = rip6_ctlinput };

VNET_DEFINE(struct in6_ifaddrhead, in6_ifaddrhead);
VNET_DEFINE(struct in6_ifaddrlisthead *, in6_ifaddrhashtbl);
VNET_DEFINE(u_long, in6_ifaddrhmask);

static struct netisr_handler ip6_nh = {
        .nh_name = "ip6",
        .nh_handler = ip6_input,
        .nh_proto = NETISR_IPV6,
#ifdef RSS
        .nh_m2cpuid = rss_soft_m2cpuid_v6,
        .nh_policy = NETISR_POLICY_CPU,
        .nh_dispatch = NETISR_DISPATCH_HYBRID,
#else
        .nh_policy = NETISR_POLICY_FLOW,
#endif
};

static int
sysctl_netinet6_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
{
        int error, qlimit;

        netisr_getqlimit(&ip6_nh, &qlimit);
        error = sysctl_handle_int(oidp, &qlimit, 0, req);
        if (error || !req->newptr)
                return (error);
        if (qlimit < 1)
                return (EINVAL);
        return (netisr_setqlimit(&ip6_nh, qlimit));
}
SYSCTL_DECL(_net_inet6_ip6);
SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRQMAXLEN, intr_queue_maxlen,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
    0, 0, sysctl_netinet6_intr_queue_maxlen, "I",
    "Maximum size of the IPv6 input queue");

VNET_DEFINE_STATIC(bool, ip6_sav) = true;
#define V_ip6_sav       VNET(ip6_sav)
SYSCTL_BOOL(_net_inet6_ip6, OID_AUTO, source_address_validation,
    CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_sav), true,
    "Drop incoming packets with source address that is a local address");

SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, temp_max_desync_factor,
    CTLFLAG_RD | CTLFLAG_VNET,
    &VNET_NAME(ip6_temp_max_desync_factor), 0,
    "RFC 8981 max desync factor");

#ifdef RSS
static struct netisr_handler ip6_direct_nh = {
        .nh_name = "ip6_direct",
        .nh_handler = ip6_direct_input,
        .nh_proto = NETISR_IPV6_DIRECT,
        .nh_m2cpuid = rss_soft_m2cpuid_v6,
        .nh_policy = NETISR_POLICY_CPU,
        .nh_dispatch = NETISR_DISPATCH_HYBRID,
};

static int
sysctl_netinet6_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS)
{
        int error, qlimit;

        netisr_getqlimit(&ip6_direct_nh, &qlimit);
        error = sysctl_handle_int(oidp, &qlimit, 0, req);
        if (error || !req->newptr)
                return (error);
        if (qlimit < 1)
                return (EINVAL);
        return (netisr_setqlimit(&ip6_direct_nh, qlimit));
}
SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRDQMAXLEN, intr_direct_queue_maxlen,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
    0, 0, sysctl_netinet6_intr_direct_queue_maxlen, "I",
    "Maximum size of the IPv6 direct input queue");

#endif

VNET_DEFINE(pfil_head_t, inet6_pfil_head);
VNET_DEFINE(pfil_head_t, inet6_local_pfil_head);

VNET_PCPUSTAT_DEFINE(struct ip6stat, ip6stat);
VNET_PCPUSTAT_SYSINIT(ip6stat);
#ifdef VIMAGE
VNET_PCPUSTAT_SYSUNINIT(ip6stat);
#endif /* VIMAGE */

struct rmlock in6_ifaddr_lock;
RM_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");

static int ip6_hopopts_input(u_int32_t *, struct mbuf **, int *);

/*
 * IP6 initialization: fill in IP6 protocol switch table.
 * All protocols not implemented in kernel go to raw IP6 protocol handler.
 */
static void
ip6_vnet_init(void *arg __unused)
{
        struct pfil_head_args args;

        TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
            &V_ip6_auto_linklocal);
        TUNABLE_INT_FETCH("net.inet6.ip6.accept_rtadv", &V_ip6_accept_rtadv);
        TUNABLE_INT_FETCH("net.inet6.ip6.no_radr", &V_ip6_no_radr);
        TUNABLE_BOOL_FETCH("net.inet6.ip6.use_stableaddr", &V_ip6_use_stableaddr);

        CK_STAILQ_INIT(&V_in6_ifaddrhead);
        V_in6_ifaddrhashtbl = hashinit(IN6ADDR_NHASH, M_IFADDR,
            &V_in6_ifaddrhmask);

        /* Initialize packet filter hooks. */
        args.pa_version = PFIL_VERSION;
        args.pa_flags = PFIL_IN | PFIL_OUT;
        args.pa_type = PFIL_TYPE_IP6;
        args.pa_headname = PFIL_INET6_NAME;
        V_inet6_pfil_head = pfil_head_register(&args);

        args.pa_flags = PFIL_OUT;
        args.pa_headname = PFIL_INET6_LOCAL_NAME;
        V_inet6_local_pfil_head = pfil_head_register(&args);

        if (hhook_head_register(HHOOK_TYPE_IPSEC_IN, AF_INET6,
            &V_ipsec_hhh_in[HHOOK_IPSEC_INET6],
            HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
                printf("%s: WARNING: unable to register input helper hook\n",
                    __func__);
        if (hhook_head_register(HHOOK_TYPE_IPSEC_OUT, AF_INET6,
            &V_ipsec_hhh_out[HHOOK_IPSEC_INET6],
            HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
                printf("%s: WARNING: unable to register output helper hook\n",
                    __func__);

        scope6_init();
        addrsel_policy_init();
        nd6_init();
        frag6_init();

        V_ip6_temp_max_desync_factor = TEMP_MAX_DESYNC_FACTOR_BASE +
            (V_ip6_temp_preferred_lifetime >> 2) +
            (V_ip6_temp_preferred_lifetime >> 3);
        V_ip6_desync_factor = arc4random() % V_ip6_temp_max_desync_factor;

        /* Skip global initialization stuff for non-default instances. */
#ifdef VIMAGE
        netisr_register_vnet(&ip6_nh);
#ifdef RSS
        netisr_register_vnet(&ip6_direct_nh);
#endif
#endif
}
VNET_SYSINIT(ip6_vnet_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
    ip6_vnet_init, NULL);

static void
ip6_init(void *arg __unused)
{
        struct ifnet *ifp;

        /*
         * Register statically those protocols that are unlikely to ever go
         * dynamic.
         */
        IP6PROTO_REGISTER(IPPROTO_ICMPV6, icmp6_input, rip6_ctlinput);
        IP6PROTO_REGISTER(IPPROTO_DSTOPTS, dest6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_ROUTING, route6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_FRAGMENT, frag6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_IPV4, encap6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_IPV6, encap6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_ETHERIP, encap6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_GRE, encap6_input, NULL);
        IP6PROTO_REGISTER(IPPROTO_PIM, encap6_input, NULL);
#ifdef SCTP     /* XXX: has a loadable & static version */
        IP6PROTO_REGISTER(IPPROTO_SCTP, sctp6_input, sctp6_ctlinput);
#endif

        EVENTHANDLER_REGISTER(vm_lowmem, frag6_drain, NULL, LOWMEM_PRI_DEFAULT);
        EVENTHANDLER_REGISTER(mbuf_lowmem, frag6_drain, NULL,
            LOWMEM_PRI_DEFAULT);

        netisr_register(&ip6_nh);
#ifdef RSS
        netisr_register(&ip6_direct_nh);
#endif
        /*
         * XXXGL: we use SYSINIT() here, but go over V_ifnet.  See comment
         * in sys/netinet/ip_input.c:ip_init().
         */
        CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link)
                in6_ifarrival(NULL, ifp);
}
SYSINIT(ip6_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_init, NULL);

int
ip6proto_register(uint8_t proto, ip6proto_input_t input,
    ip6proto_ctlinput_t ctl)
{

        MPASS(proto > 0);

        if (ip6_protox[proto] == rip6_input) {
                ip6_protox[proto] = input;
                ip6_ctlprotox[proto] = ctl;
                return (0);
        } else
                return (EEXIST);
}

int
ip6proto_unregister(uint8_t proto)
{

        MPASS(proto > 0);

        if (ip6_protox[proto] != rip6_input) {
                ip6_protox[proto] = rip6_input;
                ip6_ctlprotox[proto] = rip6_ctlinput;
                return (0);
        } else
                return (ENOENT);
}

#ifdef VIMAGE
static void
ip6_destroy(void *unused __unused)
{
        struct ifaddr *ifa, *nifa;
        struct ifnet *ifp;
        int error;

#ifdef RSS
        netisr_unregister_vnet(&ip6_direct_nh);
#endif
        netisr_unregister_vnet(&ip6_nh);

        pfil_head_unregister(V_inet6_pfil_head);
        error = hhook_head_deregister(V_ipsec_hhh_in[HHOOK_IPSEC_INET6]);
        if (error != 0) {
                printf("%s: WARNING: unable to deregister input helper hook "
                    "type HHOOK_TYPE_IPSEC_IN, id HHOOK_IPSEC_INET6: "
                    "error %d returned\n", __func__, error);
        }
        error = hhook_head_deregister(V_ipsec_hhh_out[HHOOK_IPSEC_INET6]);
        if (error != 0) {
                printf("%s: WARNING: unable to deregister output helper hook "
                    "type HHOOK_TYPE_IPSEC_OUT, id HHOOK_IPSEC_INET6: "
                    "error %d returned\n", __func__, error);
        }

        /* Cleanup addresses. */
        IFNET_RLOCK();
        CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                /* Cannot lock here - lock recursion. */
                /* IF_ADDR_LOCK(ifp); */
                CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
                        if (ifa->ifa_addr->sa_family != AF_INET6)
                                continue;
                        in6_purgeaddr(ifa);
                }
                /* IF_ADDR_UNLOCK(ifp); */
                in6_ifdetach_destroy(ifp);
        }
        IFNET_RUNLOCK();

        /* Make sure any routes are gone as well. */
        rib_flush_routes_family(AF_INET6);

        frag6_destroy();
        nd6_destroy();
        in6_ifattach_destroy();

        hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);
}

VNET_SYSUNINIT(inet6, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_destroy, NULL);
#endif

static int
ip6_input_hbh(struct mbuf **mp, uint32_t *rtalert, int *off,
    int *nxt, int *ours)
{
        struct mbuf *m;
        struct ip6_hdr *ip6;
        struct ip6_hbh *hbh;

        if (ip6_hopopts_input(rtalert, mp, off)) {
#if 0   /*touches NULL pointer*/
                in6_ifstat_inc((*mp)->m_pkthdr.rcvif, ifs6_in_discard);
#endif
                goto out;       /* m have already been freed */
        }

        /* adjust pointer */
        m = *mp;
        ip6 = mtod(m, struct ip6_hdr *);

        /*
         * If the payload length field is 0 and the next header field indicates
         * Hop-by-Hop Options header, then a Jumbo Payload option MUST be
         * included. We no not support Jumbo Payloads so report an error.
         */
        if (ip6->ip6_plen == 0) {
                IP6STAT_INC(ip6s_badoptions);
                in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
                in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
                icmp6_error(m, ICMP6_PARAM_PROB,
                            ICMP6_PARAMPROB_HEADER,
                            (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
                goto out;
        }
        /* ip6_hopopts_input() ensures that mbuf is contiguous */
        hbh = (struct ip6_hbh *)(ip6 + 1);
        *nxt = hbh->ip6h_nxt;

        /*
         * If we are acting as a router and the packet contains a
         * router alert option, see if we know the option value.
         * Currently, we only support the option value for MLD, in which
         * case we should pass the packet to the multicast routing
         * daemon.
         */
        if (*rtalert != ~0) {
                switch (*rtalert) {
                case IP6OPT_RTALERT_MLD:
                        if (V_ip6_forwarding)
                                *ours = 1;
                        break;
                default:
                        /*
                         * RFC2711 requires unrecognized values must be
                         * silently ignored.
                         */
                        break;
                }
        }

        return (0);

out:
        return (1);
}

#ifdef RSS
/*
 * IPv6 direct input routine.
 *
 * This is called when reinjecting completed fragments where
 * all of the previous checking and book-keeping has been done.
 */
void
ip6_direct_input(struct mbuf *m)
{
        int off, nxt;
        int nest;
        struct m_tag *mtag;
        struct ip6_direct_ctx *ip6dc;

        mtag = m_tag_locate(m, MTAG_ABI_IPV6, IPV6_TAG_DIRECT, NULL);
        KASSERT(mtag != NULL, ("Reinjected packet w/o direct ctx tag!"));

        ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
        nxt = ip6dc->ip6dc_nxt;
        off = ip6dc->ip6dc_off;

        nest = 0;

        m_tag_delete(m, mtag);

        while (nxt != IPPROTO_DONE) {
                if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
                        IP6STAT_INC(ip6s_toomanyhdr);
                        goto bad;
                }

                /*
                 * protection against faulty packet - there should be
                 * more sanity checks in header chain processing.
                 */
                if (m->m_pkthdr.len < off) {
                        IP6STAT_INC(ip6s_tooshort);
                        in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
                        goto bad;
                }

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
                if (IPSEC_ENABLED(ipv6)) {
                        if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
                                return;
                }
#endif /* IPSEC */

                nxt = ip6_protox[nxt](&m, &off, nxt);
        }
        return;
bad:
        m_freem(m);
}
#endif

void
ip6_input(struct mbuf *m)
{
        struct in6_addr odst;
        struct ip6_hdr *ip6;
        struct in6_ifaddr *ia;
        struct ifnet *rcvif;
        u_int32_t plen;
        u_int32_t rtalert = ~0;
        int off = sizeof(struct ip6_hdr), nest;
        int nxt, ours = 0;
        int srcrt = 0;

        /*
         * Drop the packet if IPv6 operation is disabled on the interface.
         */
        rcvif = m->m_pkthdr.rcvif;
        if ((rcvif->if_inet6->nd_flags & ND6_IFF_IFDISABLED))
                goto bad;

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
        /*
         * should the inner packet be considered authentic?
         * see comment in ah4_input().
         * NB: m cannot be NULL when passed to the input routine
         */

        m->m_flags &= ~M_AUTHIPHDR;
        m->m_flags &= ~M_AUTHIPDGM;

#endif /* IPSEC */

        if (m->m_flags & M_FASTFWD_OURS) {
                /*
                 * Firewall changed destination to local.
                 */
                ip6 = mtod(m, struct ip6_hdr *);
                goto passin;
        }

        /*
         * mbuf statistics
         */
        if (m->m_flags & M_EXT) {
                if (m->m_next)
                        IP6STAT_INC(ip6s_mext2m);
                else
                        IP6STAT_INC(ip6s_mext1);
        } else {
                if (m->m_next) {
                        struct ifnet *ifp = (m->m_flags & M_LOOP) ? V_loif : rcvif;
                        int ifindex = ifp->if_index;
                        if (ifindex >= IP6S_M2MMAX)
                                ifindex = 0;
                        IP6STAT_INC2(ip6s_m2m, ifindex);
                } else
                        IP6STAT_INC(ip6s_m1);
        }

        in6_ifstat_inc(rcvif, ifs6_in_receive);
        IP6STAT_INC(ip6s_total);

        /*
         * L2 bridge code and some other code can return mbuf chain
         * that does not conform to KAME requirement.  too bad.
         * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
         */
        if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
                struct mbuf *n;

                if (m->m_pkthdr.len > MHLEN)
                        n = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
                else
                        n = m_gethdr(M_NOWAIT, MT_DATA);
                if (n == NULL)
                        goto bad;

                m_move_pkthdr(n, m);
                m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
                n->m_len = n->m_pkthdr.len;
                m_freem(m);
                m = n;
        }
        if (m->m_len < sizeof(struct ip6_hdr)) {
                if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
                        IP6STAT_INC(ip6s_toosmall);
                        in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
                        goto bad;
                }
        }

        ip6 = mtod(m, struct ip6_hdr *);
        if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
                IP6STAT_INC(ip6s_badvers);
                in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
                goto bad;
        }

        IP6STAT_INC2(ip6s_nxthist, ip6->ip6_nxt);
        IP_PROBE(receive, NULL, NULL, ip6, rcvif, NULL, ip6);

        /*
         * Check against address spoofing/corruption.  The unspecified address
         * is checked further below.
         */
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) {
                /*
                 * XXX: "badscope" is not very suitable for a multicast source.
                 */
                IP6STAT_INC(ip6s_badscope);
                in6_ifstat_inc(rcvif, ifs6_in_addrerr);
                goto bad;
        }
        if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
            !(m->m_flags & M_LOOP)) {
                /*
                 * In this case, the packet should come from the loopback
                 * interface.  However, we cannot just check the if_flags,
                 * because ip6_mloopback() passes the "actual" interface
                 * as the outgoing/incoming interface.
                 */
                IP6STAT_INC(ip6s_badscope);
                in6_ifstat_inc(rcvif, ifs6_in_addrerr);
                goto bad;
        }
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
            IPV6_ADDR_MC_SCOPE(&ip6->ip6_dst) == 0) {
                /*
                 * RFC4291 2.7:
                 * Nodes must not originate a packet to a multicast address
                 * whose scop field contains the reserved value 0; if such
                 * a packet is received, it must be silently dropped.
                 */
                IP6STAT_INC(ip6s_badscope);
                in6_ifstat_inc(rcvif, ifs6_in_addrerr);
                goto bad;
        }
        /*
         * The following check is not documented in specs.  A malicious
         * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
         * and bypass security checks (act as if it was from 127.0.0.1 by using
         * IPv6 src ::ffff:127.0.0.1).  Be cautious.
         *
         * We have supported IPv6-only kernels for a few years and this issue
         * has not come up.  The world seems to move mostly towards not using
         * v4mapped on the wire, so it makes sense for us to keep rejecting
         * any such packets.
         */
        if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
            IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
                IP6STAT_INC(ip6s_badscope);
                in6_ifstat_inc(rcvif, ifs6_in_addrerr);
                goto bad;
        }
        /*
         * Try to forward the packet, but if we fail continue.
         * ip6_tryforward() does not generate redirects, so fall
         * through to normal processing if redirects are required.
         * ip6_tryforward() does inbound and outbound packet firewall
         * processing. If firewall has decided that destination becomes
         * our local address, it sets M_FASTFWD_OURS flag. In this
         * case skip another inbound firewall processing and update
         * ip6 pointer.
         */
        if (V_ip6_forwarding != 0 && V_ip6_sendredirects == 0
#if defined(IPSEC) || defined(IPSEC_SUPPORT)
            && (!IPSEC_ENABLED(ipv6) ||
            IPSEC_CAPS(ipv6, m, IPSEC_CAP_OPERABLE) == 0)
#endif
            ) {
                if ((m = ip6_tryforward(m)) == NULL)
                        return;
                if (m->m_flags & M_FASTFWD_OURS) {
                        ip6 = mtod(m, struct ip6_hdr *);
                        goto passin;
                }
        }
#if defined(IPSEC) || defined(IPSEC_SUPPORT)
        /*
         * Bypass packet filtering for packets previously handled by IPsec.
         */
        if (IPSEC_ENABLED(ipv6) &&
            IPSEC_CAPS(ipv6, m, IPSEC_CAP_BYPASS_FILTER) != 0)
                        goto passin;
#endif
        /*
         * Run through list of hooks for input packets.
         *
         * NB: Beware of the destination address changing
         *     (e.g. by NAT rewriting).  When this happens,
         *     tell ip6_forward to do the right thing.
         */

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

        odst = ip6->ip6_dst;
        if (pfil_mbuf_in(V_inet6_pfil_head, &m, m->m_pkthdr.rcvif,
            NULL) != PFIL_PASS)
                return;
        ip6 = mtod(m, struct ip6_hdr *);
        srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
        if ((m->m_flags & (M_IP6_NEXTHOP | M_FASTFWD_OURS)) == M_IP6_NEXTHOP &&
            m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
                /*
                 * Directly ship the packet on.  This allows forwarding
                 * packets originally destined to us to some other directly
                 * connected host.
                 */
                ip6_forward(m, 1);
                return;
        }

passin:
        /*
         * The check is deferred to here to give firewalls a chance to block
         * (and log) such packets.  ip6_tryforward() will not process such
         * packets.
         */
        if (__predict_false(IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst))) {
                IP6STAT_INC(ip6s_badscope);
                in6_ifstat_inc(rcvif, ifs6_in_addrerr);
                goto bad;
        }

        plen = (uint32_t)ntohs(ip6->ip6_plen);

        /*
         * We don't support Jumbograms, reject packets with plen == 0 as early
         * as we can.
         */
        if (plen == 0)
                goto bad;

        /*
         * Disambiguate address scope zones (if there is ambiguity).
         * We first make sure that the original source or destination address
         * is not in our internal form for scoped addresses.  Such addresses
         * are not necessarily invalid spec-wise, but we cannot accept them due
         * to the usage conflict.
         * in6_setscope() then also checks and rejects the cases where src or
         * dst are the loopback address and the receiving interface
         * is not loopback.
         */
        if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
                IP6STAT_INC(ip6s_badscope); /* XXX */
                goto bad;
        }
        if (in6_setscope(&ip6->ip6_src, rcvif, NULL) ||
            in6_setscope(&ip6->ip6_dst, rcvif, NULL)) {
                IP6STAT_INC(ip6s_badscope);
                goto bad;
        }
        if (m->m_flags & M_FASTFWD_OURS) {
                m->m_flags &= ~M_FASTFWD_OURS;
                ours = 1;
                goto hbhcheck;
        }
        /*
         * Multicast check. Assume packet is for us to avoid
         * prematurely taking locks.
         */
        if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                ours = 1;
                in6_ifstat_inc(rcvif, ifs6_in_mcast);
                goto hbhcheck;
        }
        /*
         * Unicast check
         * XXX: For now we keep link-local IPv6 addresses with embedded
         *      scope zone id, therefore we use zero zoneid here.
         */
        ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
        if (ia != NULL) {
                if (ia->ia6_flags & IN6_IFF_NOTREADY) {
                        char ip6bufs[INET6_ADDRSTRLEN];
                        char ip6bufd[INET6_ADDRSTRLEN];
                        /* address is not ready, so discard the packet. */
                        nd6log((LOG_INFO,
                            "ip6_input: packet to an unready address %s->%s\n",
                            ip6_sprintf(ip6bufs, &ip6->ip6_src),
                            ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
                        goto bad;
                }
                if (V_ip6_sav && !(m->m_flags & M_LOOP) &&
                    __predict_false(in6_localip_fib(&ip6->ip6_src,
                            rcvif->if_fib))) {
                        IP6STAT_INC(ip6s_badscope); /* XXX */
                        goto bad;
                }
                /* Count the packet in the ip address stats */
                counter_u64_add(ia->ia_ifa.ifa_ipackets, 1);
                counter_u64_add(ia->ia_ifa.ifa_ibytes, m->m_pkthdr.len);
                ours = 1;
                goto hbhcheck;
        }

        /*
         * Now there is no reason to process the packet if it's not our own
         * and we're not a router.
         */
        if (!V_ip6_forwarding) {
                IP6STAT_INC(ip6s_cantforward);
                goto bad;
        }

  hbhcheck:
        /*
         * Process Hop-by-Hop options header if it's contained.
         * m may be modified in ip6_hopopts_input().
         */
        if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
                if (ip6_input_hbh(&m, &rtalert, &off, &nxt, &ours) != 0)
                        return;
        } else
                nxt = ip6->ip6_nxt;

        /*
         * Use mbuf flags to propagate Router Alert option to
         * ICMPv6 layer, as hop-by-hop options have been stripped.
         */
        if (rtalert != ~0)
                m->m_flags |= M_RTALERT_MLD;

        /*
         * Check that the amount of data in the buffers
         * is as at least much as the IPv6 header would have us expect.
         * Trim mbufs if longer than we expect.
         * Drop packet if shorter than we expect.
         */
        if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
                IP6STAT_INC(ip6s_tooshort);
                in6_ifstat_inc(rcvif, ifs6_in_truncated);
                goto bad;
        }
        if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
                if (m->m_len == m->m_pkthdr.len) {
                        m->m_len = sizeof(struct ip6_hdr) + plen;
                        m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
                } else
                        m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
        }

        /*
         * Forward if desirable.
         */
        if (V_ip6_mrouting_enabled &&
            IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
                /*
                 * If we are acting as a multicast router, all
                 * incoming multicast packets are passed to the
                 * kernel-level multicast forwarding function.
                 * The packet is returned (relatively) intact; if
                 * ip6_mforward() returns a non-zero value, the packet
                 * must be discarded, else it may be accepted below.
                 *
                 * XXX TODO: Check hlim and multicast scope here to avoid
                 * unnecessarily calling into ip6_mforward().
                 */
                if (ip6_mforward && ip6_mforward(ip6, rcvif, m)) {
                        IP6STAT_INC(ip6s_cantforward);
                        goto bad;
                }
        } else if (!ours) {
                ip6_forward(m, srcrt);
                return;
        }

        /*
         * We are going to ship the packet to the local protocol stack. Call the
         * filter again for this 'output' action, allowing redirect-like rules
         * to adjust the source address.
         */
        if (PFIL_HOOKED_OUT(V_inet6_local_pfil_head)) {
                if (pfil_mbuf_out(V_inet6_local_pfil_head, &m, V_loif, NULL) !=
                    PFIL_PASS)
                        return;
                ip6 = mtod(m, struct ip6_hdr *);
        }

        /*
         * Tell launch routine the next header
         */
        IP6STAT_INC(ip6s_delivered);
        in6_ifstat_inc(rcvif, ifs6_in_deliver);
        nest = 0;

        while (nxt != IPPROTO_DONE) {
                if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
                        IP6STAT_INC(ip6s_toomanyhdr);
                        goto bad;
                }

                /*
                 * protection against faulty packet - there should be
                 * more sanity checks in header chain processing.
                 */
                if (m->m_pkthdr.len < off) {
                        IP6STAT_INC(ip6s_tooshort);
                        in6_ifstat_inc(rcvif, ifs6_in_truncated);
                        goto bad;
                }

#if defined(IPSEC) || defined(IPSEC_SUPPORT)
                if (IPSEC_ENABLED(ipv6)) {
                        if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
                                return;
                }
#endif /* IPSEC */

                nxt = ip6_protox[nxt](&m, &off, nxt);
        }
        return;
bad:
        in6_ifstat_inc(rcvif, ifs6_in_discard);
        if (m != NULL)
                m_freem(m);
}

/*
 * Hop-by-Hop options header processing. If a valid jumbo payload option is
 * included report an error.
 *
 * rtalertp - XXX: should be stored more smart way
 */
static int
ip6_hopopts_input(u_int32_t *rtalertp, struct mbuf **mp, int *offp)
{
        struct mbuf *m = *mp;
        int off = *offp, hbhlen;
        struct ip6_hbh *hbh;

        /* validation of the length of the header */
        if (m->m_len < off + sizeof(*hbh)) {
                m = m_pullup(m, off + sizeof(*hbh));
                if (m == NULL) {
                        IP6STAT_INC(ip6s_exthdrtoolong);
                        *mp = NULL;
                        return (-1);
                }
        }
        hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
        hbhlen = (hbh->ip6h_len + 1) << 3;

        if (m->m_len < off + hbhlen) {
                m = m_pullup(m, off + hbhlen);
                if (m == NULL) {
                        IP6STAT_INC(ip6s_exthdrtoolong);
                        *mp = NULL;
                        return (-1);
                }
        }
        hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
        off += hbhlen;
        hbhlen -= sizeof(struct ip6_hbh);
        if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
                                hbhlen, rtalertp) < 0) {
                *mp = NULL;
                return (-1);
        }

        *offp = off;
        *mp = m;
        return (0);
}

/*
 * Search header for all Hop-by-hop options and process each option.
 * This function is separate from ip6_hopopts_input() in order to
 * handle a case where the sending node itself process its hop-by-hop
 * options header. In such a case, the function is called from ip6_output().
 *
 * The function assumes that hbh header is located right after the IPv6 header
 * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
 * opthead + hbhlen is located in contiguous memory region.
 */
int
ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
    u_int32_t *rtalertp)
{
        int optlen = 0;
        u_int8_t *opt = opthead;
        u_int16_t rtalert_val;
        const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);

        for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
                switch (*opt) {
                case IP6OPT_PAD1:
                        optlen = 1;
                        break;
                case IP6OPT_PADN:
                        if (hbhlen < IP6OPT_MINLEN) {
                                IP6STAT_INC(ip6s_toosmall);
                                goto bad;
                        }
                        optlen = *(opt + 1) + 2;
                        break;
                case IP6OPT_ROUTER_ALERT:
                        /* XXX may need check for alignment */
                        if (hbhlen < IP6OPT_RTALERT_LEN) {
                                IP6STAT_INC(ip6s_toosmall);
                                goto bad;
                        }
                        if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
                                /* XXX stat */
                                icmp6_error(m, ICMP6_PARAM_PROB,
                                    ICMP6_PARAMPROB_HEADER,
                                    erroff + opt + 1 - opthead);
                                return (-1);
                        }
                        optlen = IP6OPT_RTALERT_LEN;
                        bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
                        *rtalertp = ntohs(rtalert_val);
                        break;
                case IP6OPT_JUMBO:
                        /* We do not support the Jumbo Payload option. */
                        goto bad;
                default:                /* unknown option */
                        if (hbhlen < IP6OPT_MINLEN) {
                                IP6STAT_INC(ip6s_toosmall);
                                goto bad;
                        }
                        optlen = ip6_unknown_opt(opt, m,
                            erroff + opt - opthead);
                        if (optlen == -1)
                                return (-1);
                        optlen += 2;
                        break;
                }
        }

        return (0);

  bad:
        m_freem(m);
        return (-1);
}

/*
 * Unknown option processing.
 * The third argument `off' is the offset from the IPv6 header to the option,
 * which is necessary if the IPv6 header the and option header and IPv6 header
 * is not contiguous in order to return an ICMPv6 error.
 */
int
ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
{
        struct ip6_hdr *ip6;

        switch (IP6OPT_TYPE(*optp)) {
        case IP6OPT_TYPE_SKIP: /* ignore the option */
                return ((int)*(optp + 1));
        case IP6OPT_TYPE_DISCARD:       /* silently discard */
                m_freem(m);
                return (-1);
        case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
                IP6STAT_INC(ip6s_badoptions);
                icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
                return (-1);
        case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
                IP6STAT_INC(ip6s_badoptions);
                ip6 = mtod(m, struct ip6_hdr *);
                if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
                    (m->m_flags & (M_BCAST|M_MCAST)))
                        m_freem(m);
                else
                        icmp6_error(m, ICMP6_PARAM_PROB,
                                    ICMP6_PARAMPROB_OPTION, off);
                return (-1);
        }

        m_freem(m);             /* XXX: NOTREACHED */
        return (-1);
}

/*
 * Create the "control" list for this pcb.
 * These functions will not modify mbuf chain at all.
 *
 * The routine will be called from upper layer handlers like tcp6_input().
 * Thus the routine assumes that the caller (tcp6_input) have already
 * called m_pullup() and all the extension headers are located in the
 * very first mbuf on the mbuf chain.
 *
 * ip6_savecontrol_v4 will handle those options that are possible to be
 * set on a v4-mapped socket.
 * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
 * options and handle the v6-only ones itself.
 */
struct mbuf **
ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
    int *v4only)
{
        struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);

#if defined(SO_TIMESTAMP) && defined(SO_BINTIME)
        if ((inp->inp_socket->so_options & (SO_TIMESTAMP | SO_BINTIME)) != 0) {
                union {
                        struct timeval tv;
                        struct bintime bt;
                        struct timespec ts;
                } t;
                struct bintime boottimebin, bt1;
                struct timespec ts1;
                int ts_clock;
                bool stamped;

                ts_clock = inp->inp_socket->so_ts_clock;
                stamped = false;

                /*
                 * Handle BINTIME first. We create the same output options
                 * for both SO_BINTIME and the case where SO_TIMESTAMP is
                 * set with the timestamp clock set to SO_TS_BINTIME.
                 */
                if ((inp->inp_socket->so_options & SO_BINTIME) != 0 ||
                    ts_clock == SO_TS_BINTIME) {
                        if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
                            M_TSTMP)) {
                                mbuf_tstmp2timespec(m, &ts1);
                                timespec2bintime(&ts1, &t.bt);
                                getboottimebin(&boottimebin);
                                bintime_add(&t.bt, &boottimebin);
                        } else {
                                bintime(&t.bt);
                        }
                        *mp = sbcreatecontrol(&t.bt, sizeof(t.bt), SCM_BINTIME,
                            SOL_SOCKET, M_NOWAIT);
                        if (*mp != NULL) {
                                mp = &(*mp)->m_next;
                                stamped = true;
                        }

                        /*
                         * Suppress other timestamps if SO_TIMESTAMP is not
                         * set.
                         */
                        if ((inp->inp_socket->so_options & SO_TIMESTAMP) == 0)
                                ts_clock = SO_TS_BINTIME;
                }

                switch (ts_clock) {
                case SO_TS_REALTIME_MICRO:
                        if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
                            M_TSTMP)) {
                                mbuf_tstmp2timespec(m, &ts1);
                                timespec2bintime(&ts1, &bt1);
                                getboottimebin(&boottimebin);
                                bintime_add(&bt1, &boottimebin);
                                bintime2timeval(&bt1, &t.tv);
                        } else {
                                microtime(&t.tv);
                        }
                        *mp = sbcreatecontrol(&t.tv, sizeof(t.tv),
                            SCM_TIMESTAMP, SOL_SOCKET, M_NOWAIT);
                        if (*mp != NULL) {
                                mp = &(*mp)->m_next;
                                stamped = true;
                        }
                        break;

                case SO_TS_BINTIME:
                        break;

                case SO_TS_REALTIME:
                        if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
                            M_TSTMP)) {
                                mbuf_tstmp2timespec(m, &t.ts);
                                getboottimebin(&boottimebin);
                                bintime2timespec(&boottimebin, &ts1);
                                timespecadd(&t.ts, &ts1, &t.ts);
                        } else {
                                nanotime(&t.ts);
                        }
                        *mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
                            SCM_REALTIME, SOL_SOCKET, M_NOWAIT);
                        if (*mp != NULL) {
                                mp = &(*mp)->m_next;
                                stamped = true;
                        }
                        break;

                case SO_TS_MONOTONIC:
                        if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
                            M_TSTMP))
                                mbuf_tstmp2timespec(m, &t.ts);
                        else
                                nanouptime(&t.ts);
                        *mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
                            SCM_MONOTONIC, SOL_SOCKET, M_NOWAIT);
                        if (*mp != NULL) {
                                mp = &(*mp)->m_next;
                                stamped = true;
                        }
                        break;

                default:
                        panic("unknown (corrupted) so_ts_clock");
                }
                if (stamped && (m->m_flags & (M_PKTHDR | M_TSTMP)) ==
                    (M_PKTHDR | M_TSTMP)) {
                        struct sock_timestamp_info sti;

                        bzero(&sti, sizeof(sti));
                        sti.st_info_flags = ST_INFO_HW;
                        if ((m->m_flags & M_TSTMP_HPREC) != 0)
                                sti.st_info_flags |= ST_INFO_HW_HPREC;
                        *mp = sbcreatecontrol(&sti, sizeof(sti), SCM_TIME_INFO,
                            SOL_SOCKET, M_NOWAIT);
                        if (*mp != NULL)
                                mp = &(*mp)->m_next;
                }
        }
#endif

#define IS2292(inp, x, y)       (((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
        /* RFC 2292 sec. 5 */
        if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
                struct in6_pktinfo pi6;

                if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
#ifdef INET
                        struct ip *ip;

                        ip = mtod(m, struct ip *);
                        pi6.ipi6_addr.s6_addr32[0] = 0;
                        pi6.ipi6_addr.s6_addr32[1] = 0;
                        pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
                        pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
#else
                        /* We won't hit this code */
                        bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
#endif
                } else {        
                        bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
                        in6_clearscope(&pi6.ipi6_addr); /* XXX */
                }
                pi6.ipi6_ifindex =
                    (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;

                *mp = sbcreatecontrol(&pi6, sizeof(struct in6_pktinfo),
                    IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6,
                    M_NOWAIT);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

        if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
                int hlim;

                if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
#ifdef INET
                        struct ip *ip;

                        ip = mtod(m, struct ip *);
                        hlim = ip->ip_ttl;
#else
                        /* We won't hit this code */
                        hlim = 0;
#endif
                } else {
                        hlim = ip6->ip6_hlim & 0xff;
                }
                *mp = sbcreatecontrol(&hlim, sizeof(int),
                    IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
                    IPPROTO_IPV6, M_NOWAIT);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

        if ((inp->inp_flags & IN6P_TCLASS) != 0) {
                int tclass;

                if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
#ifdef INET
                        struct ip *ip;

                        ip = mtod(m, struct ip *);
                        tclass = ip->ip_tos;
#else
                        /* We won't hit this code */
                        tclass = 0;
#endif
                } else {
                        u_int32_t flowinfo;

                        flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
                        flowinfo >>= 20;
                        tclass = flowinfo & 0xff;
                }
                *mp = sbcreatecontrol(&tclass, sizeof(int), IPV6_TCLASS,
                    IPPROTO_IPV6, M_NOWAIT);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

        if (v4only != NULL) {
                if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
                        *v4only = 1;
                } else {
                        *v4only = 0;
                }
        }

        return (mp);
}

void
ip6_savecontrol(struct inpcb *inp, struct mbuf *m, struct mbuf **mp)
{
        struct ip6_hdr *ip6;
        int v4only = 0;

        mp = ip6_savecontrol_v4(inp, m, mp, &v4only);
        if (v4only)
                return;

        ip6 = mtod(m, struct ip6_hdr *);
        /*
         * IPV6_HOPOPTS socket option.  Recall that we required super-user
         * privilege for the option (see ip6_ctloutput), but it might be too
         * strict, since there might be some hop-by-hop options which can be
         * returned to normal user.
         * See also RFC 2292 section 6 (or RFC 3542 section 8).
         */
        if ((inp->inp_flags & IN6P_HOPOPTS) != 0) {
                /*
                 * Check if a hop-by-hop options header is contatined in the
                 * received packet, and if so, store the options as ancillary
                 * data. Note that a hop-by-hop options header must be
                 * just after the IPv6 header, which is assured through the
                 * IPv6 input processing.
                 */
                if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
                        struct ip6_hbh *hbh;
                        u_int hbhlen;

                        hbh = (struct ip6_hbh *)(ip6 + 1);
                        hbhlen = (hbh->ip6h_len + 1) << 3;

                        /*
                         * XXX: We copy the whole header even if a
                         * jumbo payload option is included, the option which
                         * is to be removed before returning according to
                         * RFC2292.
                         * Note: this constraint is removed in RFC3542
                         */
                        *mp = sbcreatecontrol(hbh, hbhlen,
                            IS2292(inp, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
                            IPPROTO_IPV6, M_NOWAIT);
                        if (*mp)
                                mp = &(*mp)->m_next;
                }
        }

        if ((inp->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
                int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);

                /*
                 * Search for destination options headers or routing
                 * header(s) through the header chain, and stores each
                 * header as ancillary data.
                 * Note that the order of the headers remains in
                 * the chain of ancillary data.
                 */
                while (1) {     /* is explicit loop prevention necessary? */
                        struct ip6_ext *ip6e = NULL;
                        u_int elen;

                        /*
                         * if it is not an extension header, don't try to
                         * pull it from the chain.
                         */
                        switch (nxt) {
                        case IPPROTO_DSTOPTS:
                        case IPPROTO_ROUTING:
                        case IPPROTO_HOPOPTS:
                        case IPPROTO_AH: /* is it possible? */
                                break;
                        default:
                                goto loopend;
                        }

                        if (off + sizeof(*ip6e) > m->m_len)
                                goto loopend;
                        ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
                        if (nxt == IPPROTO_AH)
                                elen = (ip6e->ip6e_len + 2) << 2;
                        else
                                elen = (ip6e->ip6e_len + 1) << 3;
                        if (off + elen > m->m_len)
                                goto loopend;

                        switch (nxt) {
                        case IPPROTO_DSTOPTS:
                                if (!(inp->inp_flags & IN6P_DSTOPTS))
                                        break;

                                *mp = sbcreatecontrol(ip6e, elen,
                                    IS2292(inp, IPV6_2292DSTOPTS, IPV6_DSTOPTS),
                                    IPPROTO_IPV6, M_NOWAIT);
                                if (*mp)
                                        mp = &(*mp)->m_next;
                                break;
                        case IPPROTO_ROUTING:
                                if (!(inp->inp_flags & IN6P_RTHDR))
                                        break;

                                *mp = sbcreatecontrol(ip6e, elen,
                                    IS2292(inp, IPV6_2292RTHDR, IPV6_RTHDR),
                                    IPPROTO_IPV6, M_NOWAIT);
                                if (*mp)
                                        mp = &(*mp)->m_next;
                                break;
                        case IPPROTO_HOPOPTS:
                        case IPPROTO_AH: /* is it possible? */
                                break;

                        default:
                                /*
                                 * other cases have been filtered in the above.
                                 * none will visit this case.  here we supply
                                 * the code just in case (nxt overwritten or
                                 * other cases).
                                 */
                                goto loopend;
                        }

                        /* proceed with the next header. */
                        off += elen;
                        nxt = ip6e->ip6e_nxt;
                        ip6e = NULL;
                }
          loopend:
                ;
        }

        if (inp->inp_flags2 & INP_RECVFLOWID) {
                uint32_t flowid, flow_type;

                flowid = m->m_pkthdr.flowid;
                flow_type = M_HASHTYPE_GET(m);

                /*
                 * XXX should handle the failure of one or the
                 * other - don't populate both?
                 */
                *mp = sbcreatecontrol(&flowid, sizeof(uint32_t), IPV6_FLOWID,
                    IPPROTO_IPV6, M_NOWAIT);
                if (*mp)
                        mp = &(*mp)->m_next;
                *mp = sbcreatecontrol(&flow_type, sizeof(uint32_t),
                    IPV6_FLOWTYPE, IPPROTO_IPV6, M_NOWAIT);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

#ifdef  RSS
        if (inp->inp_flags2 & INP_RECVRSSBUCKETID) {
                uint32_t flowid, flow_type;
                uint32_t rss_bucketid;

                flowid = m->m_pkthdr.flowid;
                flow_type = M_HASHTYPE_GET(m);

                if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) {
                        *mp = sbcreatecontrol(&rss_bucketid, sizeof(uint32_t),
                            IPV6_RSSBUCKETID, IPPROTO_IPV6, M_NOWAIT);
                        if (*mp)
                                mp = &(*mp)->m_next;
                }
        }
#endif

}
#undef IS2292

void
ip6_notify_pmtu(struct inpcb *inp, struct sockaddr_in6 *dst, u_int32_t mtu)
{
        struct socket *so;
        struct mbuf *m_mtu;
        struct ip6_mtuinfo mtuctl;

        KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
        /*
         * Notify the error by sending IPV6_PATHMTU ancillary data if
         * application wanted to know the MTU value.
         * NOTE: we notify disconnected sockets, because some udp
         * applications keep sending sockets disconnected.
         * NOTE: our implementation doesn't notify connected sockets that has
         * foreign address that is different than given destination addresses
         * (this is permitted by RFC 3542).
         */
        if ((inp->inp_flags & IN6P_MTU) == 0 || (
            !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
            !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &dst->sin6_addr)))
                return;

        mtuctl.ip6m_mtu = mtu;
        mtuctl.ip6m_addr = *dst;
        if (sa6_recoverscope(&mtuctl.ip6m_addr))
                return;

        if ((m_mtu = sbcreatecontrol(&mtuctl, sizeof(mtuctl), IPV6_PATHMTU,
            IPPROTO_IPV6, M_NOWAIT)) == NULL)
                return;

        so =  inp->inp_socket;
        if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
            == 0) {
                soroverflow(so);
                m_freem(m_mtu);
                /* XXX: should count statistics */
        } else
                sorwakeup(so);
}

/*
 * Get pointer to the previous header followed by the header
 * currently processed.
 */
int
ip6_get_prevhdr(const struct mbuf *m, int off)
{
        struct ip6_ext ip6e;
        struct ip6_hdr *ip6;
        int len, nlen, nxt;

        if (off == sizeof(struct ip6_hdr))
                return (offsetof(struct ip6_hdr, ip6_nxt));
        if (off < sizeof(struct ip6_hdr))
                panic("%s: off < sizeof(struct ip6_hdr)", __func__);

        ip6 = mtod(m, struct ip6_hdr *);
        nxt = ip6->ip6_nxt;
        len = sizeof(struct ip6_hdr);
        nlen = 0;
        while (len < off) {
                m_copydata(m, len, sizeof(ip6e), (caddr_t)&ip6e);
                switch (nxt) {
                case IPPROTO_FRAGMENT:
                        nlen = sizeof(struct ip6_frag);
                        break;
                case IPPROTO_AH:
                        nlen = (ip6e.ip6e_len + 2) << 2;
                        break;
                default:
                        nlen = (ip6e.ip6e_len + 1) << 3;
                }
                len += nlen;
                nxt = ip6e.ip6e_nxt;
        }
        return (len - nlen);
}

/*
 * get next header offset.  m will be retained.
 */
int
ip6_nexthdr(const struct mbuf *m, int off, int proto, int *nxtp)
{
        struct ip6_hdr ip6;
        struct ip6_ext ip6e;
        struct ip6_frag fh;

        /* just in case */
        if (m == NULL)
                panic("ip6_nexthdr: m == NULL");
        if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
                return -1;

        switch (proto) {
        case IPPROTO_IPV6:
                if (m->m_pkthdr.len < off + sizeof(ip6))
                        return -1;
                m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
                if (nxtp)
                        *nxtp = ip6.ip6_nxt;
                off += sizeof(ip6);
                return off;

        case IPPROTO_FRAGMENT:
                /*
                 * terminate parsing if it is not the first fragment,
                 * it does not make sense to parse through it.
                 */
                if (m->m_pkthdr.len < off + sizeof(fh))
                        return -1;
                m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
                /* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
                if (fh.ip6f_offlg & IP6F_OFF_MASK)
                        return -1;
                if (nxtp)
                        *nxtp = fh.ip6f_nxt;
                off += sizeof(struct ip6_frag);
                return off;

        case IPPROTO_AH:
                if (m->m_pkthdr.len < off + sizeof(ip6e))
                        return -1;
                m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
                if (nxtp)
                        *nxtp = ip6e.ip6e_nxt;
                off += (ip6e.ip6e_len + 2) << 2;
                return off;

        case IPPROTO_HOPOPTS:
        case IPPROTO_ROUTING:
        case IPPROTO_DSTOPTS:
                if (m->m_pkthdr.len < off + sizeof(ip6e))
                        return -1;
                m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
                if (nxtp)
                        *nxtp = ip6e.ip6e_nxt;
                off += (ip6e.ip6e_len + 1) << 3;
                return off;

        case IPPROTO_NONE:
        case IPPROTO_ESP:
        case IPPROTO_IPCOMP:
                /* give up */
                return -1;

        default:
                return -1;
        }

        /* NOTREACHED */
}

/*
 * get offset for the last header in the chain.  m will be kept untainted.
 */
int
ip6_lasthdr(const struct mbuf *m, int off, int proto, int *nxtp)
{
        int newoff;
        int nxt;

        if (!nxtp) {
                nxt = -1;
                nxtp = &nxt;
        }
        while (1) {
                newoff = ip6_nexthdr(m, off, proto, nxtp);
                if (newoff < 0)
                        return off;
                else if (newoff < off)
                        return -1;      /* invalid */
                else if (newoff == off)
                        return newoff;

                off = newoff;
                proto = *nxtp;
        }
}