/*      $OpenBSD: ip_carp.c,v 1.372 2025/12/19 02:04:13 dlg Exp $       */

/*
 * Copyright (c) 2002 Michael Shalayeff. All rights reserved.
 * Copyright (c) 2003 Ryan McBride. All rights reserved.
 * Copyright (c) 2006-2008 Marco Pfatschbacher. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR OR HIS RELATIVES 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 MIND, 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.
 */

/*
 * TODO:
 *      - iface reconfigure
 *      - support for hardware checksum calculations;
 *
 */

#include "bridge.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/timeout.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/smr.h>
#include <sys/refcnt.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_types.h>

#include <crypto/sha1.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/if_ether.h>

#include <net/if_dl.h>

#ifdef INET6
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/in6_ifattach.h>
#endif

#include "bpfilter.h"
#if NBPFILTER > 0
#include <net/bpf.h>
#endif

#include <netinet/ip_carp.h>

/*
 * Locks used to protect data:
 *      a       atomic
 */

struct carp_mc_entry {
        LIST_ENTRY(carp_mc_entry)       mc_entries;
        union {
                struct ether_multi      *mcu_enm;
        } mc_u;
        struct sockaddr_storage         mc_addr;
};
#define mc_enm  mc_u.mcu_enm

enum { HMAC_ORIG=0, HMAC_NOV6LL=1, HMAC_MAX=2 };

struct carp_vhost_entry {
        SMR_SLIST_ENTRY(carp_vhost_entry) vhost_entries;

        struct carp_softc *parent_sc;
        int vhe_leader;
        int vhid;
        int advskew;
        enum { INIT = 0, BACKUP, MASTER }       state;
        struct timeout ad_tmo;  /* advertisement timeout */
        struct timeout md_tmo;  /* master down timeout */
        struct timeout md6_tmo; /* master down timeout */

        u_int64_t vhe_replay_cookie;

        /* authentication */
#define CARP_HMAC_PAD   64
        unsigned char vhe_pad[CARP_HMAC_PAD];
        SHA1_CTX vhe_sha1[HMAC_MAX];

        u_int8_t vhe_enaddr[ETHER_ADDR_LEN];
};

struct carp_softc {
        struct arpcom sc_ac;
#define sc_if           sc_ac.ac_if
#define sc_carpdevidx   sc_ac.ac_if.if_carpdevidx
        struct task sc_atask;
        struct task sc_ltask;
        struct task sc_dtask;
        struct ip_moptions sc_imo;
#ifdef INET6
        struct ip6_moptions sc_im6o;
        struct task sc_itask;
#endif /* INET6 */

        SMR_LIST_ENTRY(carp_softc) sc_list;
        struct refcnt sc_refcnt;

        int sc_suppress;
        int sc_bow_out;
        int sc_demote_cnt;

        int sc_sendad_errors;
#define CARP_SENDAD_MAX_ERRORS(sc) (3 * (sc)->sc_vhe_count)
        int sc_sendad_success;
#define CARP_SENDAD_MIN_SUCCESS(sc) (3 * (sc)->sc_vhe_count)

        char sc_curlladdr[ETHER_ADDR_LEN];

        SMR_SLIST_HEAD(, carp_vhost_entry) carp_vhosts;
        int sc_vhe_count;
        u_int8_t sc_vhids[CARP_MAXNODES];
        u_int8_t sc_advskews[CARP_MAXNODES];
        u_int8_t sc_balancing;

        int sc_naddrs;
        int sc_naddrs6;
        int sc_advbase;         /* seconds */

        /* authentication */
        unsigned char sc_key[CARP_KEY_LEN];

        u_int32_t sc_hashkey[2];
        u_int32_t sc_lsmask;            /* load sharing mask */
        int sc_lscount;                 /* # load sharing interfaces (max 32) */
        int sc_delayed_arp;             /* delayed ARP request countdown */
#ifdef INET6
        int sc_send_na;                 /* send NA when link state up */
#endif /* INET6 */
        int sc_realmac;                 /* using real mac */

        struct in_addr sc_peer;

        LIST_HEAD(__carp_mchead, carp_mc_entry) carp_mc_listhead;
        struct carp_vhost_entry *cur_vhe; /* current active vhe */
};

int carpctl_allow = 1;          /* [a] */
int carpctl_preempt = 0;        /* [a] */
int carpctl_log = LOG_CRIT;     /* [a] */

const struct sysctl_bounded_args carpctl_vars[] = {
        {CARPCTL_ALLOW, &carpctl_allow, INT_MIN, INT_MAX},
        {CARPCTL_PREEMPT, &carpctl_preempt, INT_MIN, INT_MAX},
        {CARPCTL_LOG, &carpctl_log, INT_MIN, INT_MAX},
};

struct cpumem *carpcounters;

int     carp_send_all_recur = 0;

#define CARP_LOG(l, sc, s)                                              \
        do {                                                            \
                if ((int)atomic_load_int(&carpctl_log) >= l) {          \
                        if (sc)                                         \
                                log(l, "%s: ",                          \
                                    (sc)->sc_if.if_xname);              \
                        else                                            \
                                log(l, "carp: ");                       \
                        addlog s;                                       \
                        addlog("\n");                                   \
                }                                                       \
        } while (0)

void    carp_hmac_prepare(struct carp_softc *);
void    carp_hmac_prepare_ctx(struct carp_vhost_entry *, u_int8_t);
void    carp_hmac_generate(struct carp_vhost_entry *, u_int32_t *,
            unsigned char *, u_int8_t);
int     carp_hmac_verify(struct carp_vhost_entry *, u_int32_t *,
            unsigned char *);
void    carp_proto_input_c(struct ifnet *, struct mbuf *,
            struct carp_header *, int, sa_family_t);
int     carp_proto_input_if(struct ifnet *, struct mbuf **, int *, int);
#ifdef INET6
int     carp6_proto_input_if(struct ifnet *, struct mbuf **, int *, int);
#endif
void    carpattach(int);
void    carpdetach(void *);
void    carp_prepare_ad(struct mbuf *, struct carp_vhost_entry *,
            struct carp_header *);
void    carp_send_ad_all(void);
void    carp_vhe_send_ad_all(struct carp_softc *);
void    carp_timer_ad(void *);
void    carp_send_ad(struct carp_vhost_entry *);
void    carp_send_arp(struct carp_softc *);
void    carp_timer_down(void *);
void    carp_master_down(struct carp_vhost_entry *);
int     carp_ioctl(struct ifnet *, u_long, caddr_t);
int     carp_vhids_ioctl(struct carp_softc *, struct carpreq *);
int     carp_check_dup_vhids(struct carp_softc *, struct carp_iflist *,
            struct carpreq *);
void    carp_ifgroup_ioctl(struct ifnet *, u_long, caddr_t);
void    carp_ifgattr_ioctl(struct ifnet *, u_long, caddr_t);
void    carp_start(struct ifnet *);
int     carp_enqueue(struct ifnet *, struct mbuf *);
void    carp_transmit(struct carp_softc *, struct ifnet *, struct mbuf *);
void    carp_setrun_all(struct carp_softc *, sa_family_t);
void    carp_setrun(struct carp_vhost_entry *, sa_family_t);
void    carp_set_state_all(struct carp_softc *, int);
void    carp_set_state(struct carp_vhost_entry *, int);
void    carp_multicast_cleanup(struct carp_softc *);
int     carp_set_ifp(struct carp_softc *, struct ifnet *);
void    carp_set_enaddr(struct carp_softc *);
void    carp_set_vhe_enaddr(struct carp_vhost_entry *);
void    carp_addr_updated(void *);
int     carp_set_addr(struct carp_softc *, struct sockaddr_in *);
int     carp_join_multicast(struct carp_softc *);
#ifdef INET6
void    carp_send_na(struct carp_softc *);
int     carp_set_addr6(struct carp_softc *, struct sockaddr_in6 *);
int     carp_join_multicast6(struct carp_softc *);
void    carp_if_linkstate(void *);
#endif
int     carp_clone_create(struct if_clone *, int);
int     carp_clone_destroy(struct ifnet *);
int     carp_ether_addmulti(struct carp_softc *, struct ifreq *);
int     carp_ether_delmulti(struct carp_softc *, struct ifreq *);
void    carp_ether_purgemulti(struct carp_softc *);
int     carp_group_demote_count(struct carp_softc *);
void    carp_update_lsmask(struct carp_softc *);
int     carp_new_vhost(struct carp_softc *, int, int);
void    carp_destroy_vhosts(struct carp_softc *);
void    carp_del_all_timeouts(struct carp_softc *);
int     carp_vhe_match(struct carp_softc *, uint64_t);

struct if_clone carp_cloner =
    IF_CLONE_INITIALIZER("carp", carp_clone_create, carp_clone_destroy);

#define carp_cksum(_m, _l)      ((u_int16_t)in_cksum((_m), (_l)))
#define CARP_IFQ_PRIO   6

void
carp_hmac_prepare(struct carp_softc *sc)
{
        struct carp_vhost_entry *vhe;
        u_int8_t i;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */

        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                for (i = 0; i < HMAC_MAX; i++) {
                        carp_hmac_prepare_ctx(vhe, i);
                }
        }
}

void
carp_hmac_prepare_ctx(struct carp_vhost_entry *vhe, u_int8_t ctx)
{
        struct carp_softc *sc = vhe->parent_sc;

        u_int8_t version = CARP_VERSION, type = CARP_ADVERTISEMENT;
        u_int8_t vhid = vhe->vhid & 0xff;
        SHA1_CTX sha1ctx;
        u_int32_t kmd[5];
        struct ifaddr *ifa;
        int i, found;
        struct in_addr last, cur, in;
#ifdef INET6
        struct in6_addr last6, cur6, in6;
#endif /* INET6 */

        /* compute ipad from key */
        memset(vhe->vhe_pad, 0, sizeof(vhe->vhe_pad));
        bcopy(sc->sc_key, vhe->vhe_pad, sizeof(sc->sc_key));
        for (i = 0; i < sizeof(vhe->vhe_pad); i++)
                vhe->vhe_pad[i] ^= 0x36;

        /* precompute first part of inner hash */
        SHA1Init(&vhe->vhe_sha1[ctx]);
        SHA1Update(&vhe->vhe_sha1[ctx], vhe->vhe_pad, sizeof(vhe->vhe_pad));
        SHA1Update(&vhe->vhe_sha1[ctx], (void *)&version, sizeof(version));
        SHA1Update(&vhe->vhe_sha1[ctx], (void *)&type, sizeof(type));

        /* generate a key for the arpbalance hash, before the vhid is hashed */
        if (vhe->vhe_leader) {
                bcopy(&vhe->vhe_sha1[ctx], &sha1ctx, sizeof(sha1ctx));
                SHA1Final((unsigned char *)kmd, &sha1ctx);
                sc->sc_hashkey[0] = kmd[0] ^ kmd[1];
                sc->sc_hashkey[1] = kmd[2] ^ kmd[3];
        }

        /* the rest of the precomputation */
        if (!sc->sc_realmac && vhe->vhe_leader &&
            memcmp(sc->sc_ac.ac_enaddr, vhe->vhe_enaddr, ETHER_ADDR_LEN) != 0)
                SHA1Update(&vhe->vhe_sha1[ctx], sc->sc_ac.ac_enaddr,
                    ETHER_ADDR_LEN);

        SHA1Update(&vhe->vhe_sha1[ctx], (void *)&vhid, sizeof(vhid));

        /* Hash the addresses from smallest to largest, not interface order */
        cur.s_addr = 0;
        do {
                found = 0;
                last = cur;
                cur.s_addr = 0xffffffff;
                TAILQ_FOREACH(ifa, &sc->sc_if.if_addrlist, ifa_list) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;
                        in.s_addr = ifatoia(ifa)->ia_addr.sin_addr.s_addr;
                        if (ntohl(in.s_addr) > ntohl(last.s_addr) &&
                            ntohl(in.s_addr) < ntohl(cur.s_addr)) {
                                cur.s_addr = in.s_addr;
                                found++;
                        }
                }
                if (found)
                        SHA1Update(&vhe->vhe_sha1[ctx],
                            (void *)&cur, sizeof(cur));
        } while (found);
#ifdef INET6
        memset(&cur6, 0x00, sizeof(cur6));
        do {
                found = 0;
                last6 = cur6;
                memset(&cur6, 0xff, sizeof(cur6));
                TAILQ_FOREACH(ifa, &sc->sc_if.if_addrlist, ifa_list) {
                        if (ifa->ifa_addr->sa_family != AF_INET6)
                                continue;
                        in6 = ifatoia6(ifa)->ia_addr.sin6_addr;
                        if (IN6_IS_SCOPE_EMBED(&in6)) {
                                if (ctx == HMAC_NOV6LL)
                                        continue;
                                in6.s6_addr16[1] = 0;
                        }
                        if (memcmp(&in6, &last6, sizeof(in6)) > 0 &&
                            memcmp(&in6, &cur6, sizeof(in6)) < 0) {
                                cur6 = in6;
                                found++;
                        }
                }
                if (found)
                        SHA1Update(&vhe->vhe_sha1[ctx],
                            (void *)&cur6, sizeof(cur6));
        } while (found);
#endif /* INET6 */

        /* convert ipad to opad */
        for (i = 0; i < sizeof(vhe->vhe_pad); i++)
                vhe->vhe_pad[i] ^= 0x36 ^ 0x5c;
}

void
carp_hmac_generate(struct carp_vhost_entry *vhe, u_int32_t counter[2],
    unsigned char md[20], u_int8_t ctx)
{
        SHA1_CTX sha1ctx;

        /* fetch first half of inner hash */
        bcopy(&vhe->vhe_sha1[ctx], &sha1ctx, sizeof(sha1ctx));

        SHA1Update(&sha1ctx, (void *)counter, sizeof(vhe->vhe_replay_cookie));
        SHA1Final(md, &sha1ctx);

        /* outer hash */
        SHA1Init(&sha1ctx);
        SHA1Update(&sha1ctx, vhe->vhe_pad, sizeof(vhe->vhe_pad));
        SHA1Update(&sha1ctx, md, 20);
        SHA1Final(md, &sha1ctx);
}

int
carp_hmac_verify(struct carp_vhost_entry *vhe, u_int32_t counter[2],
    unsigned char md[20])
{
        unsigned char md2[20];
        u_int8_t i;

        for (i = 0; i < HMAC_MAX; i++) {
                carp_hmac_generate(vhe, counter, md2, i);
                if (!timingsafe_bcmp(md, md2, sizeof(md2)))
                        return (0);
        }
        return (1);
}

int
carp_proto_input(struct mbuf **mp, int *offp, int proto, int af,
    struct netstack *ns)
{
        struct ifnet *ifp;

        ifp = if_get((*mp)->m_pkthdr.ph_ifidx);
        if (ifp == NULL) {
                m_freemp(mp);
                return IPPROTO_DONE;
        }

        proto = carp_proto_input_if(ifp, mp, offp, proto);
        if_put(ifp);
        return proto;
}

/*
 * process input packet.
 * we have rearranged checks order compared to the rfc,
 * but it seems more efficient this way or not possible otherwise.
 */
int
carp_proto_input_if(struct ifnet *ifp, struct mbuf **mp, int *offp, int proto)
{
        struct mbuf *m = *mp;
        struct ip *ip = mtod(m, struct ip *);
        struct carp_softc *sc = NULL;
        struct carp_header *ch;
        int iplen, len, ismulti;

        carpstat_inc(carps_ipackets);

        if (!atomic_load_int(&carpctl_allow)) {
                m_freem(m);
                return IPPROTO_DONE;
        }

        ismulti = IN_MULTICAST(ip->ip_dst.s_addr);

        /* check if received on a valid carp interface */
        switch (ifp->if_type) {
        case IFT_CARP:
                break;
        case IFT_ETHER:
                if (ismulti || !SMR_LIST_EMPTY_LOCKED(&ifp->if_carp))
                        break;
                /* FALLTHROUGH */
        default:
                carpstat_inc(carps_badif);
                CARP_LOG(LOG_INFO, sc,
                    ("packet received on non-carp interface: %s",
                     ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }

        /* verify that the IP TTL is 255.  */
        if (ip->ip_ttl != CARP_DFLTTL) {
                carpstat_inc(carps_badttl);
                CARP_LOG(LOG_NOTICE, sc, ("received ttl %d != %d on %s",
                    ip->ip_ttl, CARP_DFLTTL, ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }

        /*
         * verify that the received packet length is
         * equal to the CARP header
         */
        iplen = ip->ip_hl << 2;
        len = iplen + sizeof(*ch);
        if (len > m->m_pkthdr.len) {
                carpstat_inc(carps_badlen);
                CARP_LOG(LOG_INFO, sc, ("packet too short %d on %s",
                    m->m_pkthdr.len, ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }

        if ((m = *mp = m_pullup(m, len)) == NULL) {
                carpstat_inc(carps_hdrops);
                return IPPROTO_DONE;
        }
        ip = mtod(m, struct ip *);
        ch = (struct carp_header *)(mtod(m, caddr_t) + iplen);

        /* verify the CARP checksum */
        m->m_data += iplen;
        if (carp_cksum(m, len - iplen)) {
                carpstat_inc(carps_badsum);
                CARP_LOG(LOG_INFO, sc, ("checksum failed on %s",
                    ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }
        m->m_data -= iplen;

        KERNEL_LOCK();
        carp_proto_input_c(ifp, m, ch, ismulti, AF_INET);
        KERNEL_UNLOCK();
        return IPPROTO_DONE;
}

#ifdef INET6
int
carp6_proto_input(struct mbuf **mp, int *offp, int proto, int af,
    struct netstack *ns)
{
        struct ifnet *ifp;

        ifp = if_get((*mp)->m_pkthdr.ph_ifidx);
        if (ifp == NULL) {
                m_freemp(mp);
                return IPPROTO_DONE;
        }

        proto = carp6_proto_input_if(ifp, mp, offp, proto);
        if_put(ifp);
        return proto;
}

int
carp6_proto_input_if(struct ifnet *ifp, struct mbuf **mp, int *offp, int proto)
{
        struct mbuf *m = *mp;
        struct carp_softc *sc = NULL;
        struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
        struct carp_header *ch;
        u_int len;

        carpstat_inc(carps_ipackets6);

        if (!atomic_load_int(&carpctl_allow)) {
                m_freem(m);
                return IPPROTO_DONE;
        }

        /* check if received on a valid carp interface */
        if (ifp->if_type != IFT_CARP) {
                carpstat_inc(carps_badif);
                CARP_LOG(LOG_INFO, sc, ("packet received on non-carp interface: %s",
                    ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }

        /* verify that the IP TTL is 255 */
        if (ip6->ip6_hlim != CARP_DFLTTL) {
                carpstat_inc(carps_badttl);
                CARP_LOG(LOG_NOTICE, sc, ("received ttl %d != %d on %s",
                    ip6->ip6_hlim, CARP_DFLTTL, ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }

        /* verify that we have a complete carp packet */
        len = m->m_len;
        if ((m = *mp = m_pullup(m, *offp + sizeof(*ch))) == NULL) {
                carpstat_inc(carps_badlen);
                CARP_LOG(LOG_INFO, sc, ("packet size %u too small", len));
                return IPPROTO_DONE;
        }
        ch = (struct carp_header *)(mtod(m, caddr_t) + *offp);

        /* verify the CARP checksum */
        m->m_data += *offp;
        if (carp_cksum(m, sizeof(*ch))) {
                carpstat_inc(carps_badsum);
                CARP_LOG(LOG_INFO, sc, ("checksum failed, on %s",
                    ifp->if_xname));
                m_freem(m);
                return IPPROTO_DONE;
        }
        m->m_data -= *offp;

        KERNEL_LOCK();
        carp_proto_input_c(ifp, m, ch, 1, AF_INET6);
        KERNEL_UNLOCK();
        return IPPROTO_DONE;
}
#endif /* INET6 */

void
carp_proto_input_c(struct ifnet *ifp, struct mbuf *m, struct carp_header *ch,
    int ismulti, sa_family_t af)
{
        struct carp_softc *sc;
        struct ifnet *ifp0 = NULL;
        struct carp_iflist *cif;
        struct carp_vhost_entry *vhe;
        struct timeval sc_tv, ch_tv;

        KERNEL_ASSERT_LOCKED(); /* touching if_carp + carp_vhosts */

        if (ifp->if_type == IFT_CARP) {
                /*
                 * If the parent of this carp(4) got destroyed while
                 * `m' was being processed, silently drop it.
                 */
                ifp0 = if_get(ifp->if_carpdevidx);
                if (ifp0 == NULL)
                        goto rele;
                cif = &ifp0->if_carp;
        } else
                cif = &ifp->if_carp;

        SMR_LIST_FOREACH_LOCKED(sc, cif, sc_list) {
                if (af == AF_INET &&
                    ismulti != IN_MULTICAST(sc->sc_peer.s_addr))
                        continue;
                SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                        if (vhe->vhid == ch->carp_vhid)
                                goto found;
                }
        }
 found:

        if (!sc || (sc->sc_if.if_flags & (IFF_UP|IFF_RUNNING)) !=
            (IFF_UP|IFF_RUNNING)) {
                carpstat_inc(carps_badvhid);
                goto rele;
        }

        getmicrotime(&sc->sc_if.if_lastchange);

        /* verify the CARP version. */
        if (ch->carp_version != CARP_VERSION) {
                carpstat_inc(carps_badver);
                sc->sc_if.if_ierrors++;
                CARP_LOG(LOG_NOTICE, sc, ("invalid version %d != %d",
                    ch->carp_version, CARP_VERSION));
                goto rele;
        }

        /* verify the hash */
        if (carp_hmac_verify(vhe, ch->carp_counter, ch->carp_md)) {
                carpstat_inc(carps_badauth);
                sc->sc_if.if_ierrors++;
                CARP_LOG(LOG_INFO, sc, ("incorrect hash"));
                goto rele;
        }

        if (!memcmp(&vhe->vhe_replay_cookie, ch->carp_counter,
            sizeof(ch->carp_counter))) {
                struct ifnet *ifp2;

                ifp2 = if_get(sc->sc_carpdevidx);
                /* Do not log duplicates from non simplex interfaces */
                if (ifp2 && ifp2->if_flags & IFF_SIMPLEX) {
                        carpstat_inc(carps_badauth);
                        sc->sc_if.if_ierrors++;
                        CARP_LOG(LOG_WARNING, sc,
                            ("replay or network loop detected"));
                }
                if_put(ifp2);
                goto rele;
        }

        sc_tv.tv_sec = sc->sc_advbase;
        sc_tv.tv_usec = vhe->advskew * 1000000 / 256;
        ch_tv.tv_sec = ch->carp_advbase;
        ch_tv.tv_usec = ch->carp_advskew * 1000000 / 256;

        switch (vhe->state) {
        case INIT:
                break;
        case MASTER:
                /*
                 * If we receive an advertisement from a master who's going to
                 * be more frequent than us, and whose demote count is not higher
                 * than ours, go into BACKUP state. If his demote count is lower,
                 * also go into BACKUP.
                 */
                if (((timercmp(&sc_tv, &ch_tv, >) ||
                    timercmp(&sc_tv, &ch_tv, ==)) &&
                    (ch->carp_demote <= carp_group_demote_count(sc))) ||
                    ch->carp_demote < carp_group_demote_count(sc)) {
                        timeout_del(&vhe->ad_tmo);
                        carp_set_state(vhe, BACKUP);
                        carp_setrun(vhe, 0);
                }
                break;
        case BACKUP:
                /*
                 * If we're pre-empting masters who advertise slower than us,
                 * and do not have a better demote count, treat them as down.
                 *
                 */
                if (atomic_load_int(&carpctl_preempt) &&
                    timercmp(&sc_tv, &ch_tv, <) &&
                    ch->carp_demote >= carp_group_demote_count(sc)) {
                        carp_master_down(vhe);
                        break;
                }

                /*
                 * Take over masters advertising with a higher demote count,
                 * regardless of CARPCTL_PREEMPT.
                 */
                if (ch->carp_demote > carp_group_demote_count(sc)) {
                        carp_master_down(vhe);
                        break;
                }

                /*
                 *  If the master is going to advertise at such a low frequency
                 *  that he's guaranteed to time out, we'd might as well just
                 *  treat him as timed out now.
                 */
                sc_tv.tv_sec = sc->sc_advbase * 3;
                if (sc->sc_advbase && timercmp(&sc_tv, &ch_tv, <)) {
                        carp_master_down(vhe);
                        break;
                }

                /*
                 * Otherwise, we reset the counter and wait for the next
                 * advertisement.
                 */
                carp_setrun(vhe, af);
                break;
        }

rele:
        if_put(ifp0);
        m_freem(m);
        return;
}

int
carp_sysctl_carpstat(void *oldp, size_t *oldlenp, void *newp)
{
        struct carpstats carpstat;

        CTASSERT(sizeof(carpstat) == (carps_ncounters * sizeof(uint64_t)));
        memset(&carpstat, 0, sizeof carpstat);
        counters_read(carpcounters, (uint64_t *)&carpstat, carps_ncounters,
            NULL);
        return (sysctl_rdstruct(oldp, oldlenp, newp,
            &carpstat, sizeof(carpstat)));
}

int
carp_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
    size_t newlen)
{
        /* All sysctl names at this level are terminal. */
        if (namelen != 1)
                return (ENOTDIR);

        switch (name[0]) {
        case CARPCTL_STATS:
                return (carp_sysctl_carpstat(oldp, oldlenp, newp));
        default:
                return (sysctl_bounded_arr(carpctl_vars, nitems(carpctl_vars),
                    name, namelen, oldp, oldlenp, newp, newlen));
        }
}

/*
 * Interface side of the CARP implementation.
 */

void
carpattach(int n)
{
        if_creategroup("carp");  /* keep around even if empty */
        if_clone_attach(&carp_cloner);
        carpcounters = counters_alloc(carps_ncounters);
}

int
carp_clone_create(struct if_clone *ifc, int unit)
{
        struct carp_softc *sc;
        struct ifnet *ifp;

        sc = malloc(sizeof(*sc), M_DEVBUF, M_WAITOK|M_ZERO);
        refcnt_init(&sc->sc_refcnt);

        SMR_SLIST_INIT(&sc->carp_vhosts);
        sc->sc_vhe_count = 0;
        if (carp_new_vhost(sc, 0, 0)) {
                free(sc, M_DEVBUF, sizeof(*sc));
                return (ENOMEM);
        }

        task_set(&sc->sc_atask, carp_addr_updated, sc);
        task_set(&sc->sc_ltask, carp_carpdev_state, sc);
        task_set(&sc->sc_dtask, carpdetach, sc);
#ifdef INET6
        task_set(&sc->sc_itask, carp_if_linkstate, sc);
#endif /* INET6 */

        sc->sc_suppress = 0;
        sc->sc_advbase = CARP_DFLTINTV;
        sc->sc_naddrs = sc->sc_naddrs6 = 0;
#ifdef INET6
        sc->sc_im6o.im6o_hlim = CARP_DFLTTL;
#endif /* INET6 */
        sc->sc_imo.imo_membership = mallocarray(IP_MIN_MEMBERSHIPS,
            sizeof(struct in_multi *), M_IPMOPTS, M_WAITOK|M_ZERO);
        sc->sc_imo.imo_max_memberships = IP_MIN_MEMBERSHIPS;

        LIST_INIT(&sc->carp_mc_listhead);
        ifp = &sc->sc_if;
        ifp->if_softc = sc;
        snprintf(ifp->if_xname, sizeof ifp->if_xname, "%s%d", ifc->ifc_name,
            unit);
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
        ifp->if_ioctl = carp_ioctl;
        ifp->if_start = carp_start;
        ifp->if_enqueue = carp_enqueue;
        ifp->if_xflags = IFXF_CLONED;
        if_counters_alloc(ifp);
        if_attach(ifp);
        ether_ifattach(ifp);
        ifp->if_type = IFT_CARP;
        ifp->if_sadl->sdl_type = IFT_CARP;
        ifp->if_output = carp_output;
        ifp->if_priority = IF_CARP_DEFAULT_PRIORITY;
        ifp->if_link_state = LINK_STATE_INVALID;

        /* Hook carp_addr_updated to cope with address and route changes. */
        if_addrhook_add(&sc->sc_if, &sc->sc_atask);
#ifdef INET6
        if_linkstatehook_add(&sc->sc_if, &sc->sc_itask);
#endif /* INET6 */

        return (0);
}

int
carp_new_vhost(struct carp_softc *sc, int vhid, int advskew)
{
        struct carp_vhost_entry *vhe, *vhe0, *nvhe;

        vhe = malloc(sizeof(*vhe), M_DEVBUF, M_NOWAIT | M_ZERO);
        if (vhe == NULL)
                return (ENOMEM);

        refcnt_take(&sc->sc_refcnt); /* give a sc ref to the vhe */
        vhe->parent_sc = sc;
        vhe->vhid = vhid;
        vhe->advskew = advskew;
        vhe->state = INIT;
        timeout_set_proc(&vhe->ad_tmo, carp_timer_ad, vhe);
        timeout_set_proc(&vhe->md_tmo, carp_timer_down, vhe);
        timeout_set_proc(&vhe->md6_tmo, carp_timer_down, vhe);

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */

        /* mark the first vhe as leader */
        vhe0 = SMR_SLIST_FIRST_LOCKED(&sc->carp_vhosts);
        if (vhe0 == NULL) {
                vhe->vhe_leader = 1;
                SMR_SLIST_INSERT_HEAD_LOCKED(&sc->carp_vhosts,
                    vhe, vhost_entries);
                sc->sc_vhe_count = 1;
                return (0);
        }

        while ((nvhe = SMR_SLIST_NEXT_LOCKED(vhe0, vhost_entries)) != NULL)
                vhe0 = nvhe;

        SMR_SLIST_INSERT_AFTER_LOCKED(vhe0, vhe, vhost_entries);
        sc->sc_vhe_count++;

        return (0);
}

int
carp_clone_destroy(struct ifnet *ifp)
{
        struct carp_softc *sc = ifp->if_softc;

        if_addrhook_del(&sc->sc_if, &sc->sc_atask);
#ifdef INET6
        if_linkstatehook_del(&sc->sc_if, &sc->sc_itask);
#endif /* INET6 */

        NET_LOCK();
        carpdetach(sc);
        NET_UNLOCK();

        ether_ifdetach(ifp);
        if_detach(ifp);
        carp_destroy_vhosts(ifp->if_softc);
        refcnt_finalize(&sc->sc_refcnt, "carpdtor");
        free(sc->sc_imo.imo_membership, M_IPMOPTS,
            sc->sc_imo.imo_max_memberships * sizeof(struct in_multi *));
        free(sc, M_DEVBUF, sizeof(*sc));
        return (0);
}

void
carp_del_all_timeouts(struct carp_softc *sc)
{
        struct carp_vhost_entry *vhe;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                timeout_del(&vhe->ad_tmo);
                timeout_del(&vhe->md_tmo);
                timeout_del(&vhe->md6_tmo);
        }
}

void
carpdetach(void *arg)
{
        struct carp_softc *sc = arg;
        struct ifnet *ifp0;

        carp_del_all_timeouts(sc);

        if (sc->sc_demote_cnt)
                carp_group_demote_adj(&sc->sc_if, -sc->sc_demote_cnt, "detach");
        sc->sc_suppress = 0;
        sc->sc_sendad_errors = 0;

        carp_set_state_all(sc, INIT);
        sc->sc_if.if_flags &= ~IFF_UP;
        carp_setrun_all(sc, 0);
        carp_multicast_cleanup(sc);

        ifp0 = if_get(sc->sc_carpdevidx);
        if (ifp0 == NULL)
                return;

        KERNEL_ASSERT_LOCKED(); /* touching if_carp */

        SMR_LIST_REMOVE_LOCKED(sc, sc_list);
        sc->sc_carpdevidx = 0;

        smr_barrier();
        refcnt_rele_wake(&sc->sc_refcnt);

        if_linkstatehook_del(ifp0, &sc->sc_ltask);
        if_detachhook_del(ifp0, &sc->sc_dtask);
        ifpromisc(ifp0, 0);
        if_put(ifp0);
}

void
carp_destroy_vhosts(struct carp_softc *sc)
{
        /* XXX bow out? */
        struct carp_vhost_entry *vhe, *nvhe;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
        nvhe = SMR_SLIST_FIRST_LOCKED(&sc->carp_vhosts);
        SMR_SLIST_INIT(&sc->carp_vhosts);
        sc->sc_vhe_count = 0;

        smr_barrier();

        while ((vhe = nvhe) != NULL) {
                nvhe = SMR_SLIST_NEXT_LOCKED(vhe, vhost_entries);
                refcnt_rele_wake(&vhe->parent_sc->sc_refcnt);
                free(vhe, M_DEVBUF, sizeof(*vhe));
        }
}

void
carp_prepare_ad(struct mbuf *m, struct carp_vhost_entry *vhe,
    struct carp_header *ch)
{
        if (!vhe->vhe_replay_cookie) {
                arc4random_buf(&vhe->vhe_replay_cookie,
                    sizeof(vhe->vhe_replay_cookie));
        }

        bcopy(&vhe->vhe_replay_cookie, ch->carp_counter,
            sizeof(ch->carp_counter));

        /*
         * For the time being, do not include the IPv6 linklayer addresses
         * in the HMAC.
         */
        carp_hmac_generate(vhe, ch->carp_counter, ch->carp_md, HMAC_NOV6LL);
}

void
carp_send_ad_all(void)
{
        struct ifnet *ifp;
        struct carp_softc *vh;

        KERNEL_ASSERT_LOCKED(); /* touching if_carp */

        if (carp_send_all_recur > 0)
                return;
        ++carp_send_all_recur;
        TAILQ_FOREACH(ifp, &ifnetlist, if_list) {
                if (ifp->if_type != IFT_CARP)
                        continue;

                vh = ifp->if_softc;
                if ((vh->sc_if.if_flags & (IFF_UP|IFF_RUNNING)) ==
                    (IFF_UP|IFF_RUNNING)) {
                        carp_vhe_send_ad_all(vh);
                }
        }
        --carp_send_all_recur;
}

void
carp_vhe_send_ad_all(struct carp_softc *sc)
{
        struct carp_vhost_entry *vhe;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                if (vhe->state == MASTER)
                        carp_send_ad(vhe);
        }
}

void
carp_timer_ad(void *v)
{
        NET_LOCK();
        carp_send_ad(v);
        NET_UNLOCK();
}

void
carp_send_ad(struct carp_vhost_entry *vhe)
{
        struct carp_header ch;
        uint64_t usec;
        struct carp_softc *sc = vhe->parent_sc;
        struct carp_header *ch_ptr;
        struct mbuf *m;
        int error, len, advbase, advskew;
        struct ifnet *ifp;
        struct ifaddr *ifa;
        struct sockaddr sa;

        NET_ASSERT_LOCKED();

        if ((ifp = if_get(sc->sc_carpdevidx)) == NULL) {
                sc->sc_if.if_oerrors++;
                return;
        }

        /* bow out if we've gone to backup (the carp interface is going down) */
        if (sc->sc_bow_out) {
                advbase = 255;
                advskew = 255;
        } else {
                advbase = sc->sc_advbase;
                advskew = vhe->advskew;
                usec = (uint64_t)advbase * 1000000;
                usec += (uint64_t)advskew * 1000000 / 256;
                if (usec == 0)
                        usec = 1000000 / 256;
        }

        ch.carp_version = CARP_VERSION;
        ch.carp_type = CARP_ADVERTISEMENT;
        ch.carp_vhid = vhe->vhid;
        ch.carp_demote = carp_group_demote_count(sc) & 0xff;
        ch.carp_advbase = advbase;
        ch.carp_advskew = advskew;
        ch.carp_authlen = 7;    /* XXX DEFINE */
        ch.carp_cksum = 0;

        sc->cur_vhe = vhe; /* we need the vhe later on the output path */

        if (sc->sc_naddrs) {
                struct ip *ip;

                MGETHDR(m, M_DONTWAIT, MT_HEADER);
                if (m == NULL) {
                        sc->sc_if.if_oerrors++;
                        carpstat_inc(carps_onomem);
                        /* XXX maybe less ? */
                        goto retry_later;
                }
                len = sizeof(*ip) + sizeof(ch);
                m->m_pkthdr.pf.prio = CARP_IFQ_PRIO;
                m->m_pkthdr.ph_rtableid = sc->sc_if.if_rdomain;
                m->m_pkthdr.len = len;
                m->m_len = len;
                m_align(m, len);
                ip = mtod(m, struct ip *);
                ip->ip_v = IPVERSION;
                ip->ip_hl = sizeof(*ip) >> 2;
                ip->ip_tos = IPTOS_LOWDELAY;
                ip->ip_len = htons(len);
                ip->ip_id = htons(ip_randomid());
                ip->ip_off = htons(IP_DF);
                ip->ip_ttl = CARP_DFLTTL;
                ip->ip_p = IPPROTO_CARP;
                ip->ip_sum = 0;

                memset(&sa, 0, sizeof(sa));
                sa.sa_family = AF_INET;
                /* Prefer addresses on the parent interface as source for AD. */
                ifa = ifaof_ifpforaddr(&sa, ifp);
                if (ifa == NULL)
                        ifa = ifaof_ifpforaddr(&sa, &sc->sc_if);
                KASSERT(ifa != NULL);
                ip->ip_src.s_addr = ifatoia(ifa)->ia_addr.sin_addr.s_addr;
                ip->ip_dst.s_addr = sc->sc_peer.s_addr;
                if (IN_MULTICAST(ip->ip_dst.s_addr))
                        m->m_flags |= M_MCAST;

                ch_ptr = (struct carp_header *)(ip + 1);
                bcopy(&ch, ch_ptr, sizeof(ch));
                carp_prepare_ad(m, vhe, ch_ptr);

                m->m_data += sizeof(*ip);
                ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip));
                m->m_data -= sizeof(*ip);

                getmicrotime(&sc->sc_if.if_lastchange);
                carpstat_inc(carps_opackets);

                error = ip_output(m, NULL, NULL, IP_RAWOUTPUT, &sc->sc_imo,
                    NULL, 0);
                if (error &&
                    /* when unicast, the peer's down is not our fault */
                    !(!IN_MULTICAST(sc->sc_peer.s_addr) && error == EHOSTDOWN)){
                        if (error == ENOBUFS)
                                carpstat_inc(carps_onomem);
                        else
                                CARP_LOG(LOG_WARNING, sc,
                                    ("ip_output failed: %d", error));
                        sc->sc_if.if_oerrors++;
                        if (sc->sc_sendad_errors < INT_MAX)
                                sc->sc_sendad_errors++;
                        if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS(sc))
                                carp_group_demote_adj(&sc->sc_if, 1,
                                    "> snderrors");
                        sc->sc_sendad_success = 0;
                } else {
                        if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS(sc)) {
                                if (++sc->sc_sendad_success >=
                                    CARP_SENDAD_MIN_SUCCESS(sc)) {
                                        carp_group_demote_adj(&sc->sc_if, -1,
                                            "< snderrors");
                                        sc->sc_sendad_errors = 0;
                                }
                        } else
                                sc->sc_sendad_errors = 0;
                }
                if (vhe->vhe_leader) {
                        if (sc->sc_delayed_arp > 0)
                                sc->sc_delayed_arp--;
                        if (sc->sc_delayed_arp == 0) {
                                carp_send_arp(sc);
                                sc->sc_delayed_arp = -1;
                        }
                }
        }
#ifdef INET6
        if (sc->sc_naddrs6) {
                struct ip6_hdr *ip6;

                MGETHDR(m, M_DONTWAIT, MT_HEADER);
                if (m == NULL) {
                        sc->sc_if.if_oerrors++;
                        carpstat_inc(carps_onomem);
                        /* XXX maybe less ? */
                        goto retry_later;
                }
                len = sizeof(*ip6) + sizeof(ch);
                m->m_pkthdr.pf.prio = CARP_IFQ_PRIO;
                m->m_pkthdr.ph_rtableid = sc->sc_if.if_rdomain;
                m->m_pkthdr.len = len;
                m->m_len = len;
                m_align(m, len);
                m->m_flags |= M_MCAST;
                ip6 = mtod(m, struct ip6_hdr *);
                memset(ip6, 0, sizeof(*ip6));
                ip6->ip6_vfc |= IPV6_VERSION;
                ip6->ip6_hlim = CARP_DFLTTL;
                ip6->ip6_nxt = IPPROTO_CARP;

                /* set the source address */
                memset(&sa, 0, sizeof(sa));
                sa.sa_family = AF_INET6;
                /* Prefer addresses on the parent interface as source for AD. */
                ifa = ifaof_ifpforaddr(&sa, ifp);
                if (ifa == NULL)
                        ifa = ifaof_ifpforaddr(&sa, &sc->sc_if);
                KASSERT(ifa != NULL);
                bcopy(ifatoia6(ifa)->ia_addr.sin6_addr.s6_addr,
                    &ip6->ip6_src, sizeof(struct in6_addr));
                /* set the multicast destination */

                ip6->ip6_dst.s6_addr16[0] = htons(0xff02);
                ip6->ip6_dst.s6_addr16[1] = htons(ifp->if_index);
                ip6->ip6_dst.s6_addr8[15] = 0x12;

                ch_ptr = (struct carp_header *)(ip6 + 1);
                bcopy(&ch, ch_ptr, sizeof(ch));
                carp_prepare_ad(m, vhe, ch_ptr);

                m->m_data += sizeof(*ip6);
                ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip6));
                m->m_data -= sizeof(*ip6);

                getmicrotime(&sc->sc_if.if_lastchange);
                carpstat_inc(carps_opackets6);

                error = ip6_output(m, NULL, NULL, 0, &sc->sc_im6o, NULL);
                if (error) {
                        if (error == ENOBUFS)
                                carpstat_inc(carps_onomem);
                        else
                                CARP_LOG(LOG_WARNING, sc,
                                    ("ip6_output failed: %d", error));
                        sc->sc_if.if_oerrors++;
                        if (sc->sc_sendad_errors < INT_MAX)
                                sc->sc_sendad_errors++;
                        if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS(sc))
                                carp_group_demote_adj(&sc->sc_if, 1,
                                            "> snd6errors");
                        sc->sc_sendad_success = 0;
                } else {
                        if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS(sc)) {
                                if (++sc->sc_sendad_success >=
                                    CARP_SENDAD_MIN_SUCCESS(sc)) {
                                        carp_group_demote_adj(&sc->sc_if, -1,
                                            "< snd6errors");
                                        sc->sc_sendad_errors = 0;
                                }
                        } else
                                sc->sc_sendad_errors = 0;
                }
        }
#endif /* INET6 */

retry_later:
        sc->cur_vhe = NULL;
        if (advbase != 255 || advskew != 255)
                timeout_add_usec(&vhe->ad_tmo, usec);
        if_put(ifp);
}

/*
 * Broadcast a gratuitous ARP request containing
 * the virtual router MAC address for each IP address
 * associated with the virtual router.
 */
void
carp_send_arp(struct carp_softc *sc)
{
        struct ifaddr *ifa;
        in_addr_t in;

        TAILQ_FOREACH(ifa, &sc->sc_if.if_addrlist, ifa_list) {

                if (ifa->ifa_addr->sa_family != AF_INET)
                        continue;

                in = ifatoia(ifa)->ia_addr.sin_addr.s_addr;
                arprequest(&sc->sc_if, &in, &in, sc->sc_ac.ac_enaddr);
        }
}

#ifdef INET6
void
carp_send_na(struct carp_softc *sc)
{
        struct ifaddr *ifa;
        struct in6_addr *in6, mcast = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
        int i_am_router = (atomic_load_int(&ip6_forwarding) != 0);
        int flags = ND_NA_FLAG_OVERRIDE;

        if (i_am_router)
                flags |= ND_NA_FLAG_ROUTER;
        mcast.s6_addr16[1] = htons(sc->sc_if.if_index);

        TAILQ_FOREACH(ifa, &sc->sc_if.if_addrlist, ifa_list) {

                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;

                in6 = &ifatoia6(ifa)->ia_addr.sin6_addr;
                nd6_na_output(&sc->sc_if, &mcast, in6, flags, 1, NULL);
        }
}
#endif /* INET6 */

void
carp_update_lsmask(struct carp_softc *sc)
{
        struct carp_vhost_entry *vhe;
        int count;

        if (sc->sc_balancing == CARP_BAL_NONE)
                return;

        sc->sc_lsmask = 0;
        count = 0;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                if (vhe->state == MASTER && count < sizeof(sc->sc_lsmask) * 8)
                        sc->sc_lsmask |= 1 << count;
                count++;
        }
        sc->sc_lscount = count;
        CARP_LOG(LOG_DEBUG, sc, ("carp_update_lsmask: %x", sc->sc_lsmask));
}

int
carp_iamatch(struct ifnet *ifp)
{
        struct carp_softc *sc = ifp->if_softc;
        struct carp_vhost_entry *vhe;
        int match = 0;

        smr_read_enter();
        vhe = SMR_SLIST_FIRST(&sc->carp_vhosts);
        if (vhe->state == MASTER)
                match = 1;
        smr_read_leave();

        return (match);
}

#if NBRIDGE > 0
int
carp_ourether(struct ifnet *ifp0, uint8_t *ena)
{
        struct carp_softc *sc;
        uint64_t dst = ether_addr_to_e64((struct ether_addr *)ena);
        int match = 0;

        KASSERT(ifp0->if_type == IFT_ETHER);

        smr_read_enter();
        SMR_LIST_FOREACH(sc, &ifp0->if_carp, sc_list) {
                if ((sc->sc_if.if_flags & (IFF_UP|IFF_RUNNING)) !=
                    (IFF_UP|IFF_RUNNING))
                        continue;
                if (carp_vhe_match(sc, dst)) {
                        match = 1;
                        break;
                }
        }
        smr_read_leave();

        return (match);
}
#endif /* NBRIDGE > 0 */

int
carp_vhe_match(struct carp_softc *sc, uint64_t dst)
{
        struct carp_vhost_entry *vhe;
        int active = 0;

        smr_read_enter();
        vhe = SMR_SLIST_FIRST(&sc->carp_vhosts);
        active = (vhe->state == MASTER || sc->sc_balancing >= CARP_BAL_IP);
        smr_read_leave();

        return (active && (dst ==
            ether_addr_to_e64((struct ether_addr *)sc->sc_ac.ac_enaddr)));
}

struct mbuf *
carp_input(struct ifnet *ifp0, struct mbuf *m, uint64_t dst,
    struct netstack *ns)
{
        struct carp_softc *sc;

        KASSERT(ifp0->if_type == IFT_ETHER);

        smr_read_enter();
        SMR_LIST_FOREACH(sc, &ifp0->if_carp, sc_list) {
                if ((sc->sc_if.if_flags & (IFF_UP|IFF_RUNNING)) !=
                    (IFF_UP|IFF_RUNNING))
                        continue;

                if (carp_vhe_match(sc, dst)) {
                        /*
                         * These packets look like layer 2 multicast but they
                         * are unicast at layer 3. With help of the tag the
                         * mbuf's M_MCAST flag can be removed by carp_lsdrop()
                         * after we have passed layer 2.
                         */
                        if (sc->sc_balancing == CARP_BAL_IP) {
                                struct m_tag *mtag;
                                mtag = m_tag_get(PACKET_TAG_CARP_BAL_IP, 0,
                                    M_NOWAIT);
                                if (mtag == NULL) {
                                        m_freem(m);
                                        goto out;
                                }
                                m_tag_prepend(m, mtag);
                        }
                        break;
                }
        }

        if (sc != NULL) {
                if_vinput(&sc->sc_if, m, ns);
                m = NULL;
        } else if (ETH64_IS_MULTICAST(dst)) {
                /*
                 * XXX Should really check the list of multicast addresses
                 * for each CARP interface _before_ copying.
                 */
                SMR_LIST_FOREACH(sc, &ifp0->if_carp, sc_list) {
                        struct mbuf *m0;

                        if (!(sc->sc_if.if_flags & IFF_UP))
                                continue;

                        m0 = m_dup_pkt(m, ETHER_ALIGN, M_DONTWAIT);
                        if (m0 == NULL)
                                continue;

                        if_vinput(&sc->sc_if, m0, ns);
                }
        }
out:
        smr_read_leave();

        return (m);
}

int
carp_lsdrop(struct ifnet *ifp, struct mbuf *m, sa_family_t af, u_int32_t *src,
    u_int32_t *dst, int drop)
{
        struct carp_softc *sc;
        u_int32_t fold;
        struct m_tag *mtag;

        if (ifp->if_type != IFT_CARP)
                return 0;
        sc = ifp->if_softc;
        if (sc->sc_balancing == CARP_BAL_NONE)
                return 0;

        /*
         * Remove M_MCAST flag from mbuf of balancing ip traffic, since the fact
         * that it is layer 2 multicast does not implicate that it is also layer
         * 3 multicast.
         */
        if (m->m_flags & M_MCAST &&
            (mtag = m_tag_find(m, PACKET_TAG_CARP_BAL_IP, NULL))) {
                m_tag_delete(m, mtag);
                m->m_flags &= ~M_MCAST;
        }

        /*
         * Return without making a drop decision. This allows to clear the
         * M_MCAST flag and do nothing else.
         */
        if (!drop)
                return 0;

        /*
         * Never drop carp advertisements.
         * XXX Bad idea to pass all broadcast / multicast traffic?
         */
        if (m->m_flags & (M_BCAST|M_MCAST))
                return 0;

        fold = src[0] ^ dst[0];
#ifdef INET6
        if (af == AF_INET6) {
                int i;
                for (i = 1; i < 4; i++)
                        fold ^= src[i] ^ dst[i];
        }
#endif
        if (sc->sc_lscount == 0) /* just to be safe */
                return 1;

        return ((1 << (ntohl(fold) % sc->sc_lscount)) & sc->sc_lsmask) == 0;
}

void
carp_timer_down(void *v)
{
        NET_LOCK();
        carp_master_down(v);
        NET_UNLOCK();
}

void
carp_master_down(struct carp_vhost_entry *vhe)
{
        struct carp_softc *sc = vhe->parent_sc;

        NET_ASSERT_LOCKED();

        switch (vhe->state) {
        case INIT:
                printf("%s: master_down event in INIT state\n",
                    sc->sc_if.if_xname);
                break;
        case MASTER:
                break;
        case BACKUP:
                carp_set_state(vhe, MASTER);
                carp_send_ad(vhe);
                if (sc->sc_balancing == CARP_BAL_NONE && vhe->vhe_leader) {
                        carp_send_arp(sc);
                        /* Schedule a delayed ARP to deal w/ some L3 switches */
                        sc->sc_delayed_arp = 2;
#ifdef INET6
                        /* routing entry is not ready yet.  do it later */
                        sc->sc_send_na = 1;
#endif /* INET6 */
                }
                carp_setrun(vhe, 0);
                carpstat_inc(carps_preempt);
                break;
        }
}

void
carp_setrun_all(struct carp_softc *sc, sa_family_t af)
{
        struct carp_vhost_entry *vhe;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhost */
        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                carp_setrun(vhe, af);
        }
}

/*
 * When in backup state, af indicates whether to reset the master down timer
 * for v4 or v6. If it's set to zero, reset the ones which are already pending.
 */
void
carp_setrun(struct carp_vhost_entry *vhe, sa_family_t af)
{
        struct ifnet *ifp;
        struct carp_softc *sc = vhe->parent_sc;
        uint64_t usec;

        if ((ifp = if_get(sc->sc_carpdevidx)) == NULL) {
                sc->sc_if.if_flags &= ~IFF_RUNNING;
                carp_set_state_all(sc, INIT);
                return;
        }

        if (memcmp(((struct arpcom *)ifp)->ac_enaddr,
            sc->sc_ac.ac_enaddr, ETHER_ADDR_LEN) == 0)
                sc->sc_realmac = 1;
        else
                sc->sc_realmac = 0;

        if_put(ifp);

        if (sc->sc_if.if_flags & IFF_UP && vhe->vhid > 0 &&
            (sc->sc_naddrs || sc->sc_naddrs6) && !sc->sc_suppress) {
                sc->sc_if.if_flags |= IFF_RUNNING;
        } else {
                sc->sc_if.if_flags &= ~IFF_RUNNING;
                return;
        }

        usec = (uint64_t)sc->sc_advbase * 1000000;
        usec += (uint64_t)vhe->advskew * 1000000 / 256;
        if (usec == 0)
                usec = 1000000 / 256;

        switch (vhe->state) {
        case INIT:
                carp_set_state(vhe, BACKUP);
                carp_setrun(vhe, 0);
                break;
        case BACKUP:
                timeout_del(&vhe->ad_tmo);
                if (vhe->vhe_leader)
                        sc->sc_delayed_arp = -1;
                switch (af) {
                case AF_INET:
                        timeout_add_usec(&vhe->md_tmo, 3 * usec);
                        break;
#ifdef INET6
                case AF_INET6:
                        timeout_add_usec(&vhe->md6_tmo, 3 * usec);
                        break;
#endif /* INET6 */
                default:
                        if (sc->sc_naddrs)
                                timeout_add_usec(&vhe->md_tmo, 3 * usec);
                        if (sc->sc_naddrs6)
                                timeout_add_usec(&vhe->md6_tmo, 3 * usec);
                        break;
                }
                break;
        case MASTER:
                timeout_add_usec(&vhe->ad_tmo, usec);
                break;
        }
}

void
carp_multicast_cleanup(struct carp_softc *sc)
{
        struct ip_moptions *imo = &sc->sc_imo;
#ifdef INET6
        struct ip6_moptions *im6o = &sc->sc_im6o;
#endif
        u_int16_t n = imo->imo_num_memberships;

        /* Clean up our own multicast memberships */
        while (n-- > 0) {
                if (imo->imo_membership[n] != NULL) {
                        in_delmulti(imo->imo_membership[n]);
                        imo->imo_membership[n] = NULL;
                }
        }
        imo->imo_num_memberships = 0;
        imo->imo_ifidx = 0;

#ifdef INET6
        while (!LIST_EMPTY(&im6o->im6o_memberships)) {
                struct in6_multi_mship *imm =
                    LIST_FIRST(&im6o->im6o_memberships);

                LIST_REMOVE(imm, i6mm_chain);
                in6_leavegroup(imm);
        }
        im6o->im6o_ifidx = 0;
#endif

        /* And any other multicast memberships */
        carp_ether_purgemulti(sc);
}

int
carp_set_ifp(struct carp_softc *sc, struct ifnet *ifp0)
{
        struct carp_iflist *cif;
        struct carp_softc *vr, *last = NULL, *after = NULL;
        int myself = 0, error = 0;

        KERNEL_ASSERT_LOCKED(); /* touching if_carp */

        if (ifp0->if_type != IFT_ETHER)
                return (EINVAL);

        if ((ifp0->if_flags & IFF_MULTICAST) == 0)
                return (EADDRNOTAVAIL);

        KASSERT(ifp0->if_index != sc->sc_carpdevidx);

        cif = &ifp0->if_carp;
        if (carp_check_dup_vhids(sc, cif, NULL))
                return (EINVAL);

        if ((error = ifpromisc(ifp0, 1)))
                return (error);

        /* detach from old interface */
        if (sc->sc_carpdevidx != 0)
                carpdetach(sc);

        /* attach carp interface to physical interface */
        if_detachhook_add(ifp0, &sc->sc_dtask);
        if_linkstatehook_add(ifp0, &sc->sc_ltask);

        sc->sc_carpdevidx = ifp0->if_index;
        sc->sc_if.if_capabilities = ifp0->if_capabilities &
            (IFCAP_CSUM_MASK | IFCAP_TSOv4 | IFCAP_TSOv6);

        SMR_LIST_FOREACH_LOCKED(vr, cif, sc_list) {
                struct carp_vhost_entry *vrhead, *schead;
                last = vr;

                if (vr == sc)
                        myself = 1;

                vrhead = SMR_SLIST_FIRST_LOCKED(&vr->carp_vhosts);
                schead = SMR_SLIST_FIRST_LOCKED(&sc->carp_vhosts);
                if (vrhead->vhid < schead->vhid)
                        after = vr;
        }

        if (!myself) {
                refcnt_take(&sc->sc_refcnt);
                /* We're trying to keep things in order */
                if (last == NULL) {
                        SMR_LIST_INSERT_HEAD_LOCKED(cif, sc, sc_list);
                } else if (after == NULL) {
                        SMR_LIST_INSERT_AFTER_LOCKED(last, sc, sc_list);
                } else {
                        SMR_LIST_INSERT_AFTER_LOCKED(after, sc, sc_list);
                }
        }
        if (sc->sc_naddrs || sc->sc_naddrs6)
                sc->sc_if.if_flags |= IFF_UP;
        carp_set_enaddr(sc);

        carp_carpdev_state(sc);

        return (0);
}

void
carp_set_vhe_enaddr(struct carp_vhost_entry *vhe)
{
        struct carp_softc *sc = vhe->parent_sc;

        if (vhe->vhid != 0 && sc->sc_carpdevidx != 0) {
                if (vhe->vhe_leader && sc->sc_balancing == CARP_BAL_IP)
                        vhe->vhe_enaddr[0] = 1;
                else
                        vhe->vhe_enaddr[0] = 0;
                vhe->vhe_enaddr[1] = 0;
                vhe->vhe_enaddr[2] = 0x5e;
                vhe->vhe_enaddr[3] = 0;
                vhe->vhe_enaddr[4] = 1;
                vhe->vhe_enaddr[5] = vhe->vhid;
        } else
                memset(vhe->vhe_enaddr, 0, ETHER_ADDR_LEN);
}

void
carp_set_enaddr(struct carp_softc *sc)
{
        struct carp_vhost_entry *vhe;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries)
                carp_set_vhe_enaddr(vhe);

        vhe = SMR_SLIST_FIRST_LOCKED(&sc->carp_vhosts);

        /*
         * Use the carp lladdr if the running one isn't manually set.
         * Only compare static parts of the lladdr.
         */
        if ((memcmp(sc->sc_ac.ac_enaddr + 1, vhe->vhe_enaddr + 1,
            ETHER_ADDR_LEN - 2) == 0) ||
            (!sc->sc_ac.ac_enaddr[0] && !sc->sc_ac.ac_enaddr[1] &&
            !sc->sc_ac.ac_enaddr[2] && !sc->sc_ac.ac_enaddr[3] &&
            !sc->sc_ac.ac_enaddr[4] && !sc->sc_ac.ac_enaddr[5]))
                bcopy(vhe->vhe_enaddr, sc->sc_ac.ac_enaddr, ETHER_ADDR_LEN);

        /* Make sure the enaddr has changed before further twiddling. */
        if (memcmp(sc->sc_ac.ac_enaddr, sc->sc_curlladdr, ETHER_ADDR_LEN) != 0) {
                bcopy(sc->sc_ac.ac_enaddr, LLADDR(sc->sc_if.if_sadl),
                    ETHER_ADDR_LEN);
                bcopy(sc->sc_ac.ac_enaddr, sc->sc_curlladdr, ETHER_ADDR_LEN);
#ifdef INET6
                /*
                 * (re)attach a link-local address which matches
                 * our new MAC address.
                 */
                if (sc->sc_naddrs6)
                        in6_ifattach_linklocal(&sc->sc_if, NULL);
#endif
                carp_set_state_all(sc, INIT);
                carp_setrun_all(sc, 0);
        }
}

void
carp_addr_updated(void *v)
{
        struct carp_softc *sc = (struct carp_softc *) v;
        struct ifaddr *ifa;
        int new_naddrs = 0, new_naddrs6 = 0;

        TAILQ_FOREACH(ifa, &sc->sc_if.if_addrlist, ifa_list) {
                if (ifa->ifa_addr->sa_family == AF_INET)
                        new_naddrs++;
#ifdef INET6
                else if (ifa->ifa_addr->sa_family == AF_INET6)
                        new_naddrs6++;
#endif /* INET6 */
        }

        /* We received address changes from if_addrhooks callback */
        if (new_naddrs != sc->sc_naddrs || new_naddrs6 != sc->sc_naddrs6) {

                sc->sc_naddrs = new_naddrs;
                sc->sc_naddrs6 = new_naddrs6;

                /* Re-establish multicast membership removed by in_control */
                if (IN_MULTICAST(sc->sc_peer.s_addr)) {
                        if (!in_hasmulti(&sc->sc_peer, &sc->sc_if)) {
                                struct in_multi **imm =
                                    sc->sc_imo.imo_membership;
                                u_int16_t maxmem =
                                    sc->sc_imo.imo_max_memberships;

                                memset(&sc->sc_imo, 0, sizeof(sc->sc_imo));
                                sc->sc_imo.imo_membership = imm;
                                sc->sc_imo.imo_max_memberships = maxmem;

                                if (sc->sc_carpdevidx != 0 &&
                                    sc->sc_naddrs > 0)
                                        carp_join_multicast(sc);
                        }
                }

                if (sc->sc_naddrs == 0 && sc->sc_naddrs6 == 0) {
                        sc->sc_if.if_flags &= ~IFF_UP;
                        carp_set_state_all(sc, INIT);
                } else
                        carp_hmac_prepare(sc);
        }

        carp_setrun_all(sc, 0);
}

int
carp_set_addr(struct carp_softc *sc, struct sockaddr_in *sin)
{
        struct in_addr *in = &sin->sin_addr;
        int error;

        KASSERT(sc->sc_carpdevidx != 0);

        /* XXX is this necessary? */
        if (in->s_addr == INADDR_ANY) {
                carp_setrun_all(sc, 0);
                return (0);
        }

        if (sc->sc_naddrs == 0 && (error = carp_join_multicast(sc)) != 0)
                return (error);

        carp_set_state_all(sc, INIT);

        return (0);
}

int
carp_join_multicast(struct carp_softc *sc)
{
        struct ip_moptions *imo = &sc->sc_imo;
        struct in_multi *imm;
        struct in_addr addr;

        if (!IN_MULTICAST(sc->sc_peer.s_addr))
                return (0);

        addr.s_addr = sc->sc_peer.s_addr;
        if ((imm = in_addmulti(&addr, &sc->sc_if)) == NULL)
                return (ENOBUFS);

        imo->imo_membership[0] = imm;
        imo->imo_num_memberships = 1;
        imo->imo_ifidx = sc->sc_if.if_index;
        imo->imo_ttl = CARP_DFLTTL;
        imo->imo_loop = 0;
        return (0);
}


#ifdef INET6
int
carp_set_addr6(struct carp_softc *sc, struct sockaddr_in6 *sin6)
{
        int error;

        KASSERT(sc->sc_carpdevidx != 0);

        if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) {
                carp_setrun_all(sc, 0);
                return (0);
        }

        if (sc->sc_naddrs6 == 0 && (error = carp_join_multicast6(sc)) != 0)
                return (error);

        carp_set_state_all(sc, INIT);

        return (0);
}

int
carp_join_multicast6(struct carp_softc *sc)
{
        struct in6_multi_mship *imm, *imm2;
        struct ip6_moptions *im6o = &sc->sc_im6o;
        struct sockaddr_in6 addr6;
        int error;

        /* Join IPv6 CARP multicast group */
        memset(&addr6, 0, sizeof(addr6));
        addr6.sin6_family = AF_INET6;
        addr6.sin6_len = sizeof(addr6);
        addr6.sin6_addr.s6_addr16[0] = htons(0xff02);
        addr6.sin6_addr.s6_addr16[1] = htons(sc->sc_if.if_index);
        addr6.sin6_addr.s6_addr8[15] = 0x12;
        if ((imm = in6_joingroup(&sc->sc_if,
            &addr6.sin6_addr, &error)) == NULL) {
                return (error);
        }
        /* join solicited multicast address */
        memset(&addr6.sin6_addr, 0, sizeof(addr6.sin6_addr));
        addr6.sin6_addr.s6_addr16[0] = htons(0xff02);
        addr6.sin6_addr.s6_addr16[1] = htons(sc->sc_if.if_index);
        addr6.sin6_addr.s6_addr32[1] = 0;
        addr6.sin6_addr.s6_addr32[2] = htonl(1);
        addr6.sin6_addr.s6_addr32[3] = 0;
        addr6.sin6_addr.s6_addr8[12] = 0xff;
        if ((imm2 = in6_joingroup(&sc->sc_if,
            &addr6.sin6_addr, &error)) == NULL) {
                in6_leavegroup(imm);
                return (error);
        }

        /* apply v6 multicast membership */
        im6o->im6o_ifidx = sc->sc_if.if_index;
        if (imm)
                LIST_INSERT_HEAD(&im6o->im6o_memberships, imm,
                    i6mm_chain);
        if (imm2)
                LIST_INSERT_HEAD(&im6o->im6o_memberships, imm2,
                    i6mm_chain);

        return (0);
}

void
carp_if_linkstate(void *v)
{
        struct carp_softc *sc = v;

        if (sc->sc_send_na) {
                if (sc->sc_if.if_link_state == LINK_STATE_UP)
                        carp_send_na(sc);
                sc->sc_send_na = 0;
        }
}
#endif /* INET6 */

int
carp_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr)
{
        struct proc *p = curproc;       /* XXX */
        struct carp_softc *sc = ifp->if_softc;
        struct carp_vhost_entry *vhe;
        struct carpreq carpr;
        struct ifaddr *ifa = (struct ifaddr *)addr;
        struct ifreq *ifr = (struct ifreq *)addr;
        struct ifnet *ifp0 = NULL;
        int i, error = 0;

        switch (cmd) {
        case SIOCSIFADDR:
                if (sc->sc_carpdevidx == 0)
                        return (EINVAL);

                switch (ifa->ifa_addr->sa_family) {
                case AF_INET:
                        sc->sc_if.if_flags |= IFF_UP;
                        error = carp_set_addr(sc, satosin(ifa->ifa_addr));
                        break;
#ifdef INET6
                case AF_INET6:
                        sc->sc_if.if_flags |= IFF_UP;
                        error = carp_set_addr6(sc, satosin6(ifa->ifa_addr));
                        break;
#endif /* INET6 */
                default:
                        error = EAFNOSUPPORT;
                        break;
                }
                break;

        case SIOCSIFFLAGS:
                KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
                vhe = SMR_SLIST_FIRST_LOCKED(&sc->carp_vhosts);
                if (vhe->state != INIT && !(ifr->ifr_flags & IFF_UP)) {
                        carp_del_all_timeouts(sc);

                        /* we need the interface up to bow out */
                        sc->sc_if.if_flags |= IFF_UP;
                        sc->sc_bow_out = 1;
                        carp_vhe_send_ad_all(sc);
                        sc->sc_bow_out = 0;

                        sc->sc_if.if_flags &= ~IFF_UP;
                        carp_set_state_all(sc, INIT);
                        carp_setrun_all(sc, 0);
                } else if (vhe->state == INIT && (ifr->ifr_flags & IFF_UP)) {
                        sc->sc_if.if_flags |= IFF_UP;
                        carp_setrun_all(sc, 0);
                }
                break;

        case SIOCSIFXFLAGS:
                if ((ifp0 = if_get(sc->sc_carpdevidx)) != NULL) {
                        ifsetlro(ifp0, ISSET(ifr->ifr_flags, IFXF_LRO));
                        if_put(ifp0);
                }
                break;

        case SIOCSVH:
                KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
                vhe = SMR_SLIST_FIRST_LOCKED(&sc->carp_vhosts);
                if ((error = suser(p)) != 0)
                        break;
                if ((error = copyin(ifr->ifr_data, &carpr, sizeof carpr)))
                        break;
                error = 1;
                if (carpr.carpr_carpdev[0] != '\0' &&
                    (ifp0 = if_unit(carpr.carpr_carpdev)) == NULL)
                        return (EINVAL);
                if (carpr.carpr_peer.s_addr == 0)
                        sc->sc_peer.s_addr = INADDR_CARP_GROUP;
                else
                        sc->sc_peer.s_addr = carpr.carpr_peer.s_addr;
                if (ifp0 != NULL && ifp0->if_index != sc->sc_carpdevidx) {
                        if ((error = carp_set_ifp(sc, ifp0))) {
                                if_put(ifp0);
                                return (error);
                        }
                }
                if_put(ifp0);
                if (vhe->state != INIT && carpr.carpr_state != vhe->state) {
                        switch (carpr.carpr_state) {
                        case BACKUP:
                                timeout_del(&vhe->ad_tmo);
                                carp_set_state_all(sc, BACKUP);
                                carp_setrun_all(sc, 0);
                                break;
                        case MASTER:
                                KERNEL_ASSERT_LOCKED();
                                /* touching carp_vhosts */
                                SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts,
                                    vhost_entries)
                                        carp_master_down(vhe);
                                break;
                        default:
                                break;
                        }
                }
                if ((error = carp_vhids_ioctl(sc, &carpr)))
                        return (error);
                if (carpr.carpr_advbase >= 0) {
                        if (carpr.carpr_advbase > 255) {
                                error = EINVAL;
                                break;
                        }
                        sc->sc_advbase = carpr.carpr_advbase;
                        error--;
                }
                if (memcmp(sc->sc_advskews, carpr.carpr_advskews,
                    sizeof(sc->sc_advskews))) {
                        i = 0;
                        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
                        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts,
                            vhost_entries)
                                vhe->advskew = carpr.carpr_advskews[i++];
                        bcopy(carpr.carpr_advskews, sc->sc_advskews,
                            sizeof(sc->sc_advskews));
                }
                if (sc->sc_balancing != carpr.carpr_balancing) {
                        if (carpr.carpr_balancing > CARP_BAL_MAXID) {
                                error = EINVAL;
                                break;
                        }
                        sc->sc_balancing = carpr.carpr_balancing;
                        carp_set_enaddr(sc);
                        carp_update_lsmask(sc);
                }
                bcopy(carpr.carpr_key, sc->sc_key, sizeof(sc->sc_key));
                if (error > 0)
                        error = EINVAL;
                else {
                        error = 0;
                        carp_hmac_prepare(sc);
                        carp_setrun_all(sc, 0);
                }
                break;

        case SIOCGVH:
                memset(&carpr, 0, sizeof(carpr));
                if ((ifp0 = if_get(sc->sc_carpdevidx)) != NULL)
                        strlcpy(carpr.carpr_carpdev, ifp0->if_xname, IFNAMSIZ);
                if_put(ifp0);
                i = 0;
                KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
                SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                        carpr.carpr_vhids[i] = vhe->vhid;
                        carpr.carpr_advskews[i] = vhe->advskew;
                        carpr.carpr_states[i] = vhe->state;
                        i++;
                }
                carpr.carpr_advbase = sc->sc_advbase;
                carpr.carpr_balancing = sc->sc_balancing;
                if (suser(p) == 0)
                        bcopy(sc->sc_key, carpr.carpr_key,
                            sizeof(carpr.carpr_key));
                carpr.carpr_peer.s_addr = sc->sc_peer.s_addr;
                error = copyout(&carpr, ifr->ifr_data, sizeof(carpr));
                break;

        case SIOCADDMULTI:
                error = carp_ether_addmulti(sc, ifr);
                break;

        case SIOCDELMULTI:
                error = carp_ether_delmulti(sc, ifr);
                break;
        case SIOCAIFGROUP:
        case SIOCDIFGROUP:
                if (sc->sc_demote_cnt)
                        carp_ifgroup_ioctl(ifp, cmd, addr);
                break;
        case SIOCSIFGATTR:
                carp_ifgattr_ioctl(ifp, cmd, addr);
                break;
        default:
                error = ENOTTY;
        }

        if (memcmp(sc->sc_ac.ac_enaddr, sc->sc_curlladdr, ETHER_ADDR_LEN) != 0)
                carp_set_enaddr(sc);
        return (error);
}

int
carp_check_dup_vhids(struct carp_softc *sc, struct carp_iflist *cif,
    struct carpreq *carpr)
{
        struct carp_softc *vr;
        struct carp_vhost_entry *vhe, *vhe0;
        int i;

        KERNEL_ASSERT_LOCKED(); /* touching if_carp + carp_vhosts */

        SMR_LIST_FOREACH_LOCKED(vr, cif, sc_list) {
                if (vr == sc)
                        continue;
                SMR_SLIST_FOREACH_LOCKED(vhe, &vr->carp_vhosts,
                    vhost_entries) {
                        if (carpr) {
                                for (i = 0; carpr->carpr_vhids[i]; i++) {
                                        if (vhe->vhid == carpr->carpr_vhids[i])
                                                return (EINVAL);
                                }
                        }
                        SMR_SLIST_FOREACH_LOCKED(vhe0, &sc->carp_vhosts,
                            vhost_entries) {
                                if (vhe->vhid == vhe0->vhid)
                                        return (EINVAL);
                        }
                }
        }
        return (0);
}

int
carp_vhids_ioctl(struct carp_softc *sc, struct carpreq *carpr)
{
        int i, j;
        u_int8_t taken_vhids[256];

        if (carpr->carpr_vhids[0] == 0 ||
            !memcmp(sc->sc_vhids, carpr->carpr_vhids, sizeof(sc->sc_vhids)))
                return (0);

        memset(taken_vhids, 0, sizeof(taken_vhids));
        for (i = 0; carpr->carpr_vhids[i]; i++) {
                struct ifnet *ifp0;

                if (taken_vhids[carpr->carpr_vhids[i]])
                        return (EINVAL);
                taken_vhids[carpr->carpr_vhids[i]] = 1;

                if ((ifp0 = if_get(sc->sc_carpdevidx)) != NULL) {
                        if (carp_check_dup_vhids(sc, &ifp0->if_carp, carpr)) {
                                if_put(ifp0);
                                return (EINVAL);
                        }
                }
                if_put(ifp0);
                if (carpr->carpr_advskews[i] >= 255)
                        return (EINVAL);
        }
        /* set sane balancing defaults */
        if (i <= 1)
                carpr->carpr_balancing = CARP_BAL_NONE;
        else if (carpr->carpr_balancing == CARP_BAL_NONE &&
            sc->sc_balancing == CARP_BAL_NONE)
                carpr->carpr_balancing = CARP_BAL_IP;

        /* destroy all */
        carp_del_all_timeouts(sc);
        carp_destroy_vhosts(sc);
        memset(sc->sc_vhids, 0, sizeof(sc->sc_vhids));

        /* sort vhosts list by vhid */
        for (j = 1; j <= 255; j++) {
                for (i = 0; carpr->carpr_vhids[i]; i++) {
                        if (carpr->carpr_vhids[i] != j)
                                continue;
                        if (carp_new_vhost(sc, carpr->carpr_vhids[i],
                            carpr->carpr_advskews[i]))
                                return (ENOMEM);
                        sc->sc_vhids[i] = carpr->carpr_vhids[i];
                        sc->sc_advskews[i] = carpr->carpr_advskews[i];
                }
        }
        carp_set_enaddr(sc);
        carp_set_state_all(sc, INIT);
        return (0);
}

void
carp_ifgroup_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr)
{
        struct ifgroupreq *ifgr = (struct ifgroupreq *)addr;
        struct ifg_list *ifgl;
        int *dm, adj;

        if (!strcmp(ifgr->ifgr_group, IFG_ALL))
                return;
        adj = ((struct carp_softc *)ifp->if_softc)->sc_demote_cnt;
        if (cmd == SIOCDIFGROUP)
                adj = adj * -1;

        TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next)
                if (!strcmp(ifgl->ifgl_group->ifg_group, ifgr->ifgr_group)) {
                        dm = &ifgl->ifgl_group->ifg_carp_demoted;
                        if (*dm + adj >= 0)
                                *dm += adj;
                        else
                                *dm = 0;
                }
}

void
carp_ifgattr_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr)
{
        struct ifgroupreq *ifgr = (struct ifgroupreq *)addr;
        struct carp_softc *sc = ifp->if_softc;

        if (ifgr->ifgr_attrib.ifg_carp_demoted > 0 && (sc->sc_if.if_flags &
            (IFF_UP|IFF_RUNNING)) == (IFF_UP|IFF_RUNNING))
                carp_vhe_send_ad_all(sc);
}

void
carp_start(struct ifnet *ifp)
{
        struct carp_softc *sc = ifp->if_softc;
        struct ifnet *ifp0;
        struct mbuf *m;

        if ((ifp0 = if_get(sc->sc_carpdevidx)) == NULL) {
                ifq_purge(&ifp->if_snd);
                return;
        }

        while ((m = ifq_dequeue(&ifp->if_snd)) != NULL)
                carp_transmit(sc, ifp0, m);
        if_put(ifp0);
}

void
carp_transmit(struct carp_softc *sc, struct ifnet *ifp0, struct mbuf *m)
{
        struct ifnet *ifp = &sc->sc_if;

#if NBPFILTER > 0
        {
                caddr_t if_bpf = ifp->if_bpf;
                if (if_bpf)
                        bpf_mtap_ether(if_bpf, m, BPF_DIRECTION_OUT);
        }
#endif /* NBPFILTER > 0 */

        if (!ISSET(ifp0->if_flags, IFF_RUNNING)) {
                counters_inc(ifp->if_counters, ifc_oerrors);
                m_freem(m);
                return;
        }

        /*
         * Do not leak the multicast address when sending
         * advertisements in 'ip' and 'ip-stealth' balancing
         * modes.
         */
        if (sc->sc_balancing == CARP_BAL_IP ||
            sc->sc_balancing == CARP_BAL_IPSTEALTH) {
                struct ether_header *eh = mtod(m, struct ether_header *);
                memcpy(eh->ether_shost, sc->sc_ac.ac_enaddr,
                    sizeof(eh->ether_shost));
        }

        if (if_enqueue(ifp0, m))
                counters_inc(ifp->if_counters, ifc_oerrors);
}

int
carp_enqueue(struct ifnet *ifp, struct mbuf *m)
{
        struct carp_softc *sc = ifp->if_softc;
        struct ifnet *ifp0;

        /* no ifq_is_priq, cos hfsc on carp doesn't make sense */

        /*
         * If the parent of this carp(4) got destroyed while
         * `m' was being processed, silently drop it.
         */
        if ((ifp0 = if_get(sc->sc_carpdevidx)) == NULL) {
                m_freem(m);
                return (0);
        }

        counters_pkt(ifp->if_counters,
            ifc_opackets, ifc_obytes, m->m_pkthdr.len);
        carp_transmit(sc, ifp0, m);
        if_put(ifp0);

        return (0);
}

int
carp_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *sa,
    struct rtentry *rt)
{
        struct carp_softc *sc = ((struct carp_softc *)ifp->if_softc);
        struct carp_vhost_entry *vhe;
        int ismaster;

        if (sc->cur_vhe == NULL) {
                smr_read_enter();
                vhe = SMR_SLIST_FIRST(&sc->carp_vhosts);
                ismaster = (vhe->state == MASTER);
                smr_read_leave();
        } else {
                ismaster = (sc->cur_vhe->state == MASTER);
        }

        if ((sc->sc_balancing == CARP_BAL_NONE && !ismaster)) {
                m_freem(m);
                return (ENETUNREACH);
        }

        return (ether_output(ifp, m, sa, rt));
}

void
carp_set_state_all(struct carp_softc *sc, int state)
{
        struct carp_vhost_entry *vhe;

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */
        SMR_SLIST_FOREACH_LOCKED(vhe, &sc->carp_vhosts, vhost_entries) {
                if (vhe->state == state)
                        continue;

                carp_set_state(vhe, state);
        }
}

void
carp_set_state(struct carp_vhost_entry *vhe, int state)
{
        struct carp_softc *sc = vhe->parent_sc;
        static const char *carp_states[] = { CARP_STATES };
        int loglevel;
        struct carp_vhost_entry *vhe0;

        KASSERT(vhe->state != state);

        if (vhe->state == INIT || state == INIT)
                loglevel = LOG_WARNING;
        else
                loglevel = LOG_CRIT;

        if (sc->sc_vhe_count > 1)
                CARP_LOG(loglevel, sc,
                    ("state transition (vhid %d): %s -> %s", vhe->vhid,
                    carp_states[vhe->state], carp_states[state]));
        else
                CARP_LOG(loglevel, sc,
                    ("state transition: %s -> %s",
                    carp_states[vhe->state], carp_states[state]));

        vhe->state = state;
        carp_update_lsmask(sc);

        KERNEL_ASSERT_LOCKED(); /* touching carp_vhosts */

        sc->sc_if.if_link_state = LINK_STATE_INVALID;
        SMR_SLIST_FOREACH_LOCKED(vhe0, &sc->carp_vhosts, vhost_entries) {
                /*
                 * Link must be up if at least one vhe is in state MASTER to
                 * bring or keep route up.
                 */
                if (vhe0->state == MASTER) {
                        sc->sc_if.if_link_state = LINK_STATE_UP;
                        break;
                } else if (vhe0->state == BACKUP) {
                        sc->sc_if.if_link_state = LINK_STATE_DOWN;
                }
        }
        if_link_state_change(&sc->sc_if);
}

void
carp_group_demote_adj(struct ifnet *ifp, int adj, char *reason)
{
        struct ifg_list *ifgl;
        int *dm, need_ad;
        struct carp_softc *nil = NULL;

        if (ifp->if_type == IFT_CARP) {
                dm = &((struct carp_softc *)ifp->if_softc)->sc_demote_cnt;
                if (*dm + adj >= 0)
                        *dm += adj;
                else
                        *dm = 0;
        }

        need_ad = 0;
        TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next) {
                if (!strcmp(ifgl->ifgl_group->ifg_group, IFG_ALL))
                        continue;
                dm = &ifgl->ifgl_group->ifg_carp_demoted;

                if (*dm + adj >= 0)
                        *dm += adj;
                else
                        *dm = 0;

                if (adj > 0 && *dm == 1)
                        need_ad = 1;
                CARP_LOG(LOG_ERR, nil,
                    ("%s demoted group %s by %d to %d (%s)",
                    ifp->if_xname, ifgl->ifgl_group->ifg_group,
                    adj, *dm, reason));
        }
        if (need_ad)
                carp_send_ad_all();
}

int
carp_group_demote_count(struct carp_softc *sc)
{
        struct ifg_list *ifgl;
        int count = 0;

        TAILQ_FOREACH(ifgl, &sc->sc_if.if_groups, ifgl_next)
                count += ifgl->ifgl_group->ifg_carp_demoted;

        if (count == 0 && sc->sc_demote_cnt)
                count = sc->sc_demote_cnt;

        return (count > 255 ? 255 : count);
}

void
carp_carpdev_state(void *v)
{
        struct carp_softc *sc = v;
        struct ifnet *ifp0;
        int suppressed = sc->sc_suppress;

        if ((ifp0 = if_get(sc->sc_carpdevidx)) == NULL)
                return;

        if (ifp0->if_link_state == LINK_STATE_DOWN ||
            !(ifp0->if_flags & IFF_UP)) {
                sc->sc_if.if_flags &= ~IFF_RUNNING;
                carp_del_all_timeouts(sc);
                carp_set_state_all(sc, INIT);
                sc->sc_suppress = 1;
                carp_setrun_all(sc, 0);
                if (!suppressed)
                        carp_group_demote_adj(&sc->sc_if, 1, "carpdev");
        } else if (suppressed) {
                carp_set_state_all(sc, INIT);
                sc->sc_suppress = 0;
                carp_setrun_all(sc, 0);
                carp_group_demote_adj(&sc->sc_if, -1, "carpdev");
        }

        if_put(ifp0);
}

int
carp_ether_addmulti(struct carp_softc *sc, struct ifreq *ifr)
{
        struct ifnet *ifp0;
        struct carp_mc_entry *mc;
        u_int8_t addrlo[ETHER_ADDR_LEN], addrhi[ETHER_ADDR_LEN];
        int error;

        ifp0 = if_get(sc->sc_carpdevidx);
        if (ifp0 == NULL)
                return (EINVAL);

        error = ether_addmulti(ifr, (struct arpcom *)&sc->sc_ac);
        if (error != ENETRESET) {
                if_put(ifp0);
                return (error);
        }

        /*
         * This is new multicast address.  We have to tell parent
         * about it.  Also, remember this multicast address so that
         * we can delete them on unconfigure.
         */
        mc = malloc(sizeof(*mc), M_DEVBUF, M_NOWAIT);
        if (mc == NULL) {
                error = ENOMEM;
                goto alloc_failed;
        }

        /*
         * As ether_addmulti() returns ENETRESET, following two
         * statement shouldn't fail.
         */
        (void)ether_multiaddr(&ifr->ifr_addr, addrlo, addrhi);
        ETHER_LOOKUP_MULTI(addrlo, addrhi, &sc->sc_ac, mc->mc_enm);
        memcpy(&mc->mc_addr, &ifr->ifr_addr, ifr->ifr_addr.sa_len);
        LIST_INSERT_HEAD(&sc->carp_mc_listhead, mc, mc_entries);

        error = (*ifp0->if_ioctl)(ifp0, SIOCADDMULTI, (caddr_t)ifr);
        if (error != 0)
                goto ioctl_failed;

        if_put(ifp0);

        return (error);

 ioctl_failed:
        LIST_REMOVE(mc, mc_entries);
        free(mc, M_DEVBUF, sizeof(*mc));
 alloc_failed:
        (void)ether_delmulti(ifr, (struct arpcom *)&sc->sc_ac);
        if_put(ifp0);

        return (error);
}

int
carp_ether_delmulti(struct carp_softc *sc, struct ifreq *ifr)
{
        struct ifnet *ifp0;
        struct ether_multi *enm;
        struct carp_mc_entry *mc;
        u_int8_t addrlo[ETHER_ADDR_LEN], addrhi[ETHER_ADDR_LEN];
        int error;

        ifp0 = if_get(sc->sc_carpdevidx);
        if (ifp0 == NULL)
                return (EINVAL);

        /*
         * Find a key to lookup carp_mc_entry.  We have to do this
         * before calling ether_delmulti for obvious reason.
         */
        if ((error = ether_multiaddr(&ifr->ifr_addr, addrlo, addrhi)) != 0)
                goto rele;
        ETHER_LOOKUP_MULTI(addrlo, addrhi, &sc->sc_ac, enm);
        if (enm == NULL) {
                error = EINVAL;
                goto rele;
        }

        LIST_FOREACH(mc, &sc->carp_mc_listhead, mc_entries)
                if (mc->mc_enm == enm)
                        break;

        /* We won't delete entries we didn't add */
        if (mc == NULL) {
                error = EINVAL;
                goto rele;
        }

        error = ether_delmulti(ifr, (struct arpcom *)&sc->sc_ac);
        if (error != ENETRESET)
                goto rele;

        /* We no longer use this multicast address.  Tell parent so. */
        error = (*ifp0->if_ioctl)(ifp0, SIOCDELMULTI, (caddr_t)ifr);
        if (error == 0) {
                /* And forget about this address. */
                LIST_REMOVE(mc, mc_entries);
                free(mc, M_DEVBUF, sizeof(*mc));
        } else
                (void)ether_addmulti(ifr, (struct arpcom *)&sc->sc_ac);
rele:
        if_put(ifp0);
        return (error);
}

/*
 * Delete any multicast address we have asked to add from parent
 * interface.  Called when the carp is being unconfigured.
 */
void
carp_ether_purgemulti(struct carp_softc *sc)
{
        struct ifnet *ifp0;             /* Parent. */
        struct carp_mc_entry *mc;
        union {
                struct ifreq ifreq;
                struct {
                        char ifr_name[IFNAMSIZ];
                        struct sockaddr_storage ifr_ss;
                } ifreq_storage;
        } u;
        struct ifreq *ifr = &u.ifreq;

        if ((ifp0 = if_get(sc->sc_carpdevidx)) == NULL)
                return;

        memcpy(ifr->ifr_name, ifp0->if_xname, IFNAMSIZ);
        while ((mc = LIST_FIRST(&sc->carp_mc_listhead)) != NULL) {
                memcpy(&ifr->ifr_addr, &mc->mc_addr, mc->mc_addr.ss_len);
                (void)(*ifp0->if_ioctl)(ifp0, SIOCDELMULTI, (caddr_t)ifr);
                LIST_REMOVE(mc, mc_entries);
                free(mc, M_DEVBUF, sizeof(*mc));
        }

        if_put(ifp0);
}