/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (C) 2001 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 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"

#define IN_HISTORICAL_NETS              /* include class masks */

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/systm.h>
#include <sys/sockio.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/socket.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/sx.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_arp.h>
#include <net/if_dl.h>
#include <net/if_llatbl.h>
#include <net/if_private.h>
#include <net/if_types.h>
#include <net/if_bridgevar.h>
#include <net/route.h>
#include <net/route/nhop.h>
#include <net/route/route_ctl.h>
#include <net/vnet.h>

#include <netinet/if_ether.h>
#include <netinet/in.h>
#include <netinet/in_fib.h>
#include <netinet/in_var.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/ip_carp.h>
#include <netinet/igmp_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#ifdef MAC
#include <security/mac/mac_framework.h>
#endif

static int in_aifaddr_ioctl(u_long, caddr_t, struct ifnet *, struct ucred *);
static int in_difaddr_ioctl(u_long, caddr_t, struct ifnet *, struct ucred *);
static int in_gifaddr_ioctl(u_long, caddr_t, struct ifnet *, struct ucred *);

static void     in_socktrim(struct sockaddr_in *);
static void     in_purgemaddrs(struct ifnet *);

static bool     ia_need_loopback_route(const struct in_ifaddr *);

VNET_DEFINE_STATIC(int, nosameprefix);
#define V_nosameprefix                  VNET(nosameprefix)
SYSCTL_INT(_net_inet_ip, OID_AUTO, no_same_prefix, CTLFLAG_VNET | CTLFLAG_RW,
        &VNET_NAME(nosameprefix), 0,
        "Refuse to create same prefixes on different interfaces");

VNET_DEFINE_STATIC(bool, broadcast_lowest);
#define V_broadcast_lowest              VNET(broadcast_lowest)
SYSCTL_BOOL(_net_inet_ip, OID_AUTO, broadcast_lowest, CTLFLAG_VNET | CTLFLAG_RW,
        &VNET_NAME(broadcast_lowest), 0,
        "Treat lowest address on a subnet (host 0) as broadcast");

VNET_DEFINE(bool, ip_allow_net240) = false;
#define V_ip_allow_net240               VNET(ip_allow_net240)
SYSCTL_BOOL(_net_inet_ip, OID_AUTO, allow_net240,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip_allow_net240), 0,
        "Allow forwarding of and ICMP response to Experimental addresses, aka Class E (240/4)");
/* see https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-240 */

VNET_DEFINE(bool, ip_allow_net0) = false;
SYSCTL_BOOL(_net_inet_ip, OID_AUTO, allow_net0,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip_allow_net0), 0,
        "Allow forwarding of and ICMP response to addresses in network 0/8");
/* see https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-0 */

VNET_DEFINE(uint32_t, in_loopback_mask) = IN_LOOPBACK_MASK_DFLT;
#define V_in_loopback_mask      VNET(in_loopback_mask)
static int sysctl_loopback_prefixlen(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_net_inet_ip, OID_AUTO, loopback_prefixlen,
        CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW,
        NULL, 0, sysctl_loopback_prefixlen, "I",
        "Prefix length of address space reserved for loopback");
/* see https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127 */

VNET_DECLARE(struct inpcbinfo, ripcbinfo);
#define V_ripcbinfo                     VNET(ripcbinfo)

static struct sx in_control_sx;
SX_SYSINIT(in_control_sx, &in_control_sx, "in_control");

/*
 * Return true if an internet address is for a ``local'' host
 * (one to which we have a connection).
 */
bool
in_localaddr(struct in_addr in)
{
        u_long i = ntohl(in.s_addr);
        struct in_ifaddr *ia;

        NET_EPOCH_ASSERT();

        CK_STAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
                if ((i & ia->ia_subnetmask) == ia->ia_subnet)
                        return (true);
        }

        return (false);
}

/*
 * Return true if an internet address is for the local host and configured
 * on one of its interfaces.
 */
bool
in_localip(struct in_addr in)
{
        struct in_ifaddr *ia;

        NET_EPOCH_ASSERT();

        CK_LIST_FOREACH(ia, INADDR_HASH(in.s_addr), ia_hash)
                if (IA_SIN(ia)->sin_addr.s_addr == in.s_addr)
                        return (true);

        return (false);
}

/*
 * Like in_localip(), but FIB-aware and carp(4)-aware.
 */
bool
in_localip_fib(struct in_addr in, uint16_t fib)
{
        struct in_ifaddr *ia;

        NET_EPOCH_ASSERT();

        CK_LIST_FOREACH(ia, INADDR_HASH(in.s_addr), ia_hash)
                if (IA_SIN(ia)->sin_addr.s_addr == in.s_addr &&
                    (ia->ia_ifa.ifa_carp == NULL ||
                    carp_master_p(&ia->ia_ifa)) &&
                    ia->ia_ifa.ifa_ifp->if_fib == fib)
                        return (true);

        return (false);
}

/*
 * Return true if an internet address is configured on an interface.
 */
bool
in_ifhasaddr(struct ifnet *ifp, struct in_addr in)
{
        struct ifaddr *ifa;
        struct in_ifaddr *ia;

        NET_EPOCH_ASSERT();

        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                if (ifa->ifa_addr->sa_family != AF_INET)
                        continue;
                ia = (struct in_ifaddr *)ifa;
                if (ia->ia_addr.sin_addr.s_addr == in.s_addr)
                        return (true);
        }

        return (false);
}

/*
 * Return the first configured IPv4 address on the given ifnet.
 * Replaces deprecated IFP_TO_IA() from 4.3BSD.
 * Used only by IPv4 multicast, where source-address selection
 * has not yet been introduced.
 *
 * Returns ifa or NULL.
 */
struct in_ifaddr *
in_ifprimaryaddr(struct ifnet *ifp)
{
        struct ifaddr *ifa;

        NET_EPOCH_ASSERT();

        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
                if (ifa->ifa_addr->sa_family == AF_INET)
                        break;

        return ((struct in_ifaddr *)ifa);
}

/*
 * Return a reference to the interface address which is different to
 * the supplied one but with same IP address value.
 */
static struct in_ifaddr *
in_localip_more(struct in_ifaddr *original_ia)
{
        struct epoch_tracker et;
        in_addr_t original_addr = IA_SIN(original_ia)->sin_addr.s_addr;
        uint32_t original_fib = original_ia->ia_ifa.ifa_ifp->if_fib;
        struct in_ifaddr *ia;

        NET_EPOCH_ENTER(et);
        CK_LIST_FOREACH(ia, INADDR_HASH(original_addr), ia_hash) {
                in_addr_t addr = IA_SIN(ia)->sin_addr.s_addr;
                uint32_t fib = ia->ia_ifa.ifa_ifp->if_fib;
                if (!V_rt_add_addr_allfibs && (original_fib != fib))
                        continue;
                if ((original_ia != ia) && (original_addr == addr)) {
                        ifa_ref(&ia->ia_ifa);
                        NET_EPOCH_EXIT(et);
                        return (ia);
                }
        }
        NET_EPOCH_EXIT(et);

        return (NULL);
}

/*
 * Tries to find first IPv4 address in the provided fib.
 * Prefers non-loopback addresses and return loopback IFF
 * @loopback_ok is set.
 *
 * Returns ifa or NULL.
 */
struct in_ifaddr *
in_findlocal(uint32_t fibnum, bool loopback_ok)
{
        struct in_ifaddr *ia = NULL, *ia_lo = NULL;

        NET_EPOCH_ASSERT();

        CK_STAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
                uint32_t ia_fib = ia->ia_ifa.ifa_ifp->if_fib;
                if (!V_rt_add_addr_allfibs && (fibnum != ia_fib))
                        continue;

                if (!IN_LOOPBACK(ntohl(IA_SIN(ia)->sin_addr.s_addr)))
                        break;
                if (loopback_ok)
                        ia_lo = ia;
        }

        if (ia == NULL)
                ia = ia_lo;

        return (ia);
}

/*
 * Determine whether an IP address is in a reserved set of addresses
 * that may not be forwarded, or whether datagrams to that destination
 * may be forwarded.
 */
bool
in_canforward(struct in_addr in)
{
        u_long i = ntohl(in.s_addr);

        if (IN_MULTICAST(i) || IN_LINKLOCAL(i) || IN_LOOPBACK(i) ||
            in_nullhost(in))
                return (false);
        if (IN_EXPERIMENTAL(i) && !V_ip_allow_net240)
                return (false);
        if (IN_ZERONET(i) && !V_ip_allow_net0)
                return (false);
        return (true);
}

/*
 * Sysctl to manage prefix of reserved loopback network; translate
 * to/from mask.  The mask is always contiguous high-order 1 bits
 * followed by all 0 bits.
 */
static int
sysctl_loopback_prefixlen(SYSCTL_HANDLER_ARGS)
{
        int error, preflen;

        /* ffs is 1-based; compensate. */
        preflen = 33 - ffs(V_in_loopback_mask);
        error = sysctl_handle_int(oidp, &preflen, 0, req);
        if (error || !req->newptr)
                return (error);
        if (preflen < 8 || preflen > 31)
                return (EINVAL);
        V_in_loopback_mask = 0xffffffff << (32 - preflen);
        return (0);
}

/*
 * Trim a mask in a sockaddr
 */
static void
in_socktrim(struct sockaddr_in *ap)
{
    char *cplim = (char *) &ap->sin_addr;
    char *cp = (char *) (&ap->sin_addr + 1);

    ap->sin_len = 0;
    while (--cp >= cplim)
        if (*cp) {
            (ap)->sin_len = cp - (char *) (ap) + 1;
            break;
        }
}

/*
 * Generic internet control operations (ioctl's).
 */
int
in_control_ioctl(u_long cmd, void *data, struct ifnet *ifp,
    struct ucred *cred)
{
        struct ifreq *ifr = (struct ifreq *)data;
        struct sockaddr_in *addr = (struct sockaddr_in *)&ifr->ifr_addr;
        struct epoch_tracker et;
        struct ifaddr *ifa;
        struct in_ifaddr *ia;
        int error;

        if (ifp == NULL)
                return (EADDRNOTAVAIL);

        /*
         * Filter out 4 ioctls we implement directly.  Forward the rest
         * to specific functions and ifp->if_ioctl().
         */
        switch (cmd) {
        case SIOCGIFADDR:
        case SIOCGIFBRDADDR:
        case SIOCGIFDSTADDR:
        case SIOCGIFNETMASK:
                break;
        case SIOCGIFALIAS:
                sx_xlock(&in_control_sx);
                error = in_gifaddr_ioctl(cmd, data, ifp, cred);
                sx_xunlock(&in_control_sx);
                return (error);
        case SIOCDIFADDR:
                sx_xlock(&in_control_sx);
                error = in_difaddr_ioctl(cmd, data, ifp, cred);
                sx_xunlock(&in_control_sx);
                return (error);
        case OSIOCAIFADDR:      /* 9.x compat */
        case SIOCAIFADDR:
                sx_xlock(&in_control_sx);
                error = in_aifaddr_ioctl(cmd, data, ifp, cred);
                sx_xunlock(&in_control_sx);
                return (error);
        case SIOCSIFADDR:
        case SIOCSIFBRDADDR:
        case SIOCSIFDSTADDR:
        case SIOCSIFNETMASK:
                /* We no longer support that old commands. */
                return (EINVAL);
        default:
                if (ifp->if_ioctl == NULL)
                        return (EOPNOTSUPP);
                return ((*ifp->if_ioctl)(ifp, cmd, data));
        }

        if (addr->sin_addr.s_addr != INADDR_ANY &&
            prison_check_ip4(cred, &addr->sin_addr) != 0)
                return (EADDRNOTAVAIL);

        /*
         * Find address for this interface, if it exists.  If an
         * address was specified, find that one instead of the
         * first one on the interface, if possible.
         */
        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                if (ifa->ifa_addr->sa_family != AF_INET)
                        continue;
                ia = (struct in_ifaddr *)ifa;
                if (ia->ia_addr.sin_addr.s_addr == addr->sin_addr.s_addr)
                        break;
        }
        if (ifa == NULL)
                CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
                        if (ifa->ifa_addr->sa_family == AF_INET) {
                                ia = (struct in_ifaddr *)ifa;
                                if (prison_check_ip4(cred,
                                    &ia->ia_addr.sin_addr) == 0)
                                        break;
                        }

        if (ifa == NULL) {
                NET_EPOCH_EXIT(et);
                return (EADDRNOTAVAIL);
        }

        error = 0;
        switch (cmd) {
        case SIOCGIFADDR:
                *addr = ia->ia_addr;
                break;

        case SIOCGIFBRDADDR:
                if ((ifp->if_flags & IFF_BROADCAST) == 0) {
                        error = EINVAL;
                        break;
                }
                *addr = ia->ia_broadaddr;
                break;

        case SIOCGIFDSTADDR:
                if ((ifp->if_flags & IFF_POINTOPOINT) == 0) {
                        error = EINVAL;
                        break;
                }
                *addr = ia->ia_dstaddr;
                break;

        case SIOCGIFNETMASK:
                *addr = ia->ia_sockmask;
                break;
        }

        NET_EPOCH_EXIT(et);

        return (error);
}

int
in_mask2len(struct in_addr *mask)
{
        int x, y;
        u_char *p;

        p = (u_char *)mask;
        for (x = 0; x < sizeof(*mask); x++) {
                if (p[x] != 0xff)
                        break;
        }
        y = 0;
        if (x < sizeof(*mask)) {
                for (y = 0; y < 8; y++) {
                        if ((p[x] & (0x80 >> y)) == 0)
                                break;
                }
        }
        return (x * 8 + y);
}

int
in_control(struct socket *so, u_long cmd, void *data, struct ifnet *ifp,
    struct thread *td)
{
        return (in_control_ioctl(cmd, data, ifp, td ? td->td_ucred : NULL));
}

static int
in_aifaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct ucred *cred)
{
        const struct in_aliasreq *ifra = (struct in_aliasreq *)data;
        const struct sockaddr_in *addr = &ifra->ifra_addr;
        const struct sockaddr_in *broadaddr = &ifra->ifra_broadaddr;
        const struct sockaddr_in *mask = &ifra->ifra_mask;
        const struct sockaddr_in *dstaddr = &ifra->ifra_dstaddr;
        const int vhid = (cmd == SIOCAIFADDR) ? ifra->ifra_vhid : 0;
        struct epoch_tracker et;
        struct ifaddr *ifa;
        struct in_ifaddr *ia;
        bool iaIsFirst;
        int error = 0;

        error = priv_check_cred(cred, PRIV_NET_ADDIFADDR);
        if (error)
                return (error);

        /*
         * ifra_addr must be present and be of INET family.
         * ifra_broadaddr/ifra_dstaddr and ifra_mask are optional.
         */
        if (addr->sin_len != sizeof(struct sockaddr_in) ||
            addr->sin_family != AF_INET)
                return (EINVAL);
        if (broadaddr->sin_len != 0 &&
            (broadaddr->sin_len != sizeof(struct sockaddr_in) ||
            broadaddr->sin_family != AF_INET))
                return (EINVAL);
        if (mask->sin_len != 0 &&
            (mask->sin_len != sizeof(struct sockaddr_in) ||
            mask->sin_family != AF_INET))
                return (EINVAL);
        if ((ifp->if_flags & IFF_POINTOPOINT) &&
            (dstaddr->sin_len != sizeof(struct sockaddr_in) ||
             dstaddr->sin_addr.s_addr == INADDR_ANY))
                return (EDESTADDRREQ);
        if (vhid != 0 && carp_attach_p == NULL)
                return (EPROTONOSUPPORT);

#ifdef MAC
        /* Check if a MAC policy disallows setting the IPv4 address. */
        error = mac_inet_check_add_addr(cred, &addr->sin_addr, ifp);
        if (error != 0)
                return (error);
#endif

        /*
         * Check if bridge wants to allow adding addrs to member interfaces.
         */
        if (ifp->if_bridge != NULL && ifp->if_type != IFT_GIF &&
            bridge_member_ifaddrs_p != NULL) {
                if (bridge_member_ifaddrs_p())
                        if_printf(ifp, "WARNING: Assigning an IP address to "
                            "an interface which is also a bridge member is "
                            "deprecated and will be unsupported in a future "
                            "release.\n");
                else
                        return (EINVAL);
        }

        /*
         * See whether address already exist.
         */
        iaIsFirst = true;
        ia = NULL;
        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                struct in_ifaddr *it;

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

                it = (struct in_ifaddr *)ifa;
                if (it->ia_addr.sin_addr.s_addr == addr->sin_addr.s_addr &&
                    prison_check_ip4(cred, &addr->sin_addr) == 0)
                        ia = it;
                else
                        iaIsFirst = false;
        }
        NET_EPOCH_EXIT(et);

        if (ia != NULL)
                (void )in_difaddr_ioctl(cmd, data, ifp, cred);

        ifa = ifa_alloc(sizeof(struct in_ifaddr), M_WAITOK);
        ia = (struct in_ifaddr *)ifa;
        ifa->ifa_addr = (struct sockaddr *)&ia->ia_addr;
        ifa->ifa_dstaddr = (struct sockaddr *)&ia->ia_dstaddr;
        ifa->ifa_netmask = (struct sockaddr *)&ia->ia_sockmask;
        callout_init_rw(&ia->ia_garp_timer, &ifp->if_addr_lock,
            CALLOUT_RETURNUNLOCKED);

        ia->ia_ifp = ifp;
        ia->ia_addr = *addr;
        if (mask->sin_len != 0) {
                ia->ia_sockmask = *mask;
                ia->ia_subnetmask = ntohl(ia->ia_sockmask.sin_addr.s_addr);
        } else {
                in_addr_t i = ntohl(addr->sin_addr.s_addr);

                /*
                 * If netmask isn't supplied, use historical default.
                 * This is deprecated for interfaces other than loopback
                 * or point-to-point; warn in other cases.  In the future
                 * we should return an error rather than warning.
                 */
                if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) == 0)
                        printf("%s: set address: WARNING: network mask "
                             "should be specified; using historical default\n",
                             ifp->if_xname);
                if (IN_CLASSA(i))
                        ia->ia_subnetmask = IN_CLASSA_NET;
                else if (IN_CLASSB(i))
                        ia->ia_subnetmask = IN_CLASSB_NET;
                else
                        ia->ia_subnetmask = IN_CLASSC_NET;
                ia->ia_sockmask.sin_addr.s_addr = htonl(ia->ia_subnetmask);
        }
        ia->ia_subnet = ntohl(addr->sin_addr.s_addr) & ia->ia_subnetmask;
        in_socktrim(&ia->ia_sockmask);

        if (ifp->if_flags & IFF_BROADCAST) {
                if (broadaddr->sin_len != 0) {
                        ia->ia_broadaddr = *broadaddr;
                } else if (ia->ia_subnetmask == IN_RFC3021_MASK) {
                        ia->ia_broadaddr.sin_addr.s_addr = INADDR_BROADCAST;
                        ia->ia_broadaddr.sin_len = sizeof(struct sockaddr_in);
                        ia->ia_broadaddr.sin_family = AF_INET;
                } else {
                        ia->ia_broadaddr.sin_addr.s_addr =
                            htonl(ia->ia_subnet | ~ia->ia_subnetmask);
                        ia->ia_broadaddr.sin_len = sizeof(struct sockaddr_in);
                        ia->ia_broadaddr.sin_family = AF_INET;
                }
        }

        if (ifp->if_flags & IFF_POINTOPOINT)
                ia->ia_dstaddr = *dstaddr;

        if (vhid != 0) {
                error = (*carp_attach_p)(&ia->ia_ifa, vhid);
                if (error)
                        return (error);
        }

        /* if_addrhead is already referenced by ifa_alloc() */
        IF_ADDR_WLOCK(ifp);
        CK_STAILQ_INSERT_TAIL(&ifp->if_addrhead, ifa, ifa_link);
        IF_ADDR_WUNLOCK(ifp);

        ifa_ref(ifa);                   /* in_ifaddrhead */
        sx_assert(&in_control_sx, SA_XLOCKED);
        CK_STAILQ_INSERT_TAIL(&V_in_ifaddrhead, ia, ia_link);
        CK_LIST_INSERT_HEAD(INADDR_HASH(ia->ia_addr.sin_addr.s_addr), ia,
            ia_hash);

        /*
         * Give the interface a chance to initialize
         * if this is its first address,
         * and to validate the address if necessary.
         */
        if (ifp->if_ioctl != NULL) {
                error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia);
                if (error)
                        goto fail1;
        }

        /*
         * Add route for the network.
         */
        if (vhid == 0) {
                error = in_addprefix(ia);
                if (error)
                        goto fail1;
        }

        /*
         * Add a loopback route to self.
         */
        if (vhid == 0 && ia_need_loopback_route(ia)) {
                struct in_ifaddr *eia;

                eia = in_localip_more(ia);

                if (eia == NULL) {
                        error = ifa_add_loopback_route((struct ifaddr *)ia,
                            (struct sockaddr *)&ia->ia_addr);
                        if (error)
                                goto fail2;
                } else
                        ifa_free(&eia->ia_ifa);
        }

        if (iaIsFirst && (ifp->if_flags & IFF_MULTICAST)) {
                struct in_addr allhosts_addr;
                struct in_ifinfo *ii;

                ii = (struct in_ifinfo *)ifp->if_inet;
                allhosts_addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);

                error = in_joingroup(ifp, &allhosts_addr, NULL,
                        &ii->ii_allhosts);
        }

        /*
         * Note: we don't need extra reference for ifa, since we called
         * with sx lock held, and ifaddr can not be deleted in concurrent
         * thread.
         */
        EVENTHANDLER_INVOKE(ifaddr_event_ext, ifp, ifa, IFADDR_EVENT_ADD);

        return (error);

fail2:
        if (vhid == 0)
                (void )in_scrubprefix(ia, LLE_STATIC);

fail1:
        if (ia->ia_ifa.ifa_carp)
                (*carp_detach_p)(&ia->ia_ifa, false);

        IF_ADDR_WLOCK(ifp);
        CK_STAILQ_REMOVE(&ifp->if_addrhead, &ia->ia_ifa, ifaddr, ifa_link);
        IF_ADDR_WUNLOCK(ifp);
        ifa_free(&ia->ia_ifa);          /* if_addrhead */

        sx_assert(&in_control_sx, SA_XLOCKED);
        CK_STAILQ_REMOVE(&V_in_ifaddrhead, ia, in_ifaddr, ia_link);
        CK_LIST_REMOVE(ia, ia_hash);
        ifa_free(&ia->ia_ifa);          /* in_ifaddrhead */

        return (error);
}

static int
in_difaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct ucred *cred)
{
        const struct ifreq *ifr = (struct ifreq *)data;
        const struct sockaddr_in *addr = (const struct sockaddr_in *)
            &ifr->ifr_addr;
        struct ifaddr *ifa;
        struct in_ifaddr *ia;
        bool deleteAny, iaIsLast;
        int error;

        if (cred != NULL) {
                error = priv_check_cred(cred, PRIV_NET_DELIFADDR);
                if (error)
                        return (error);
        }

        if (addr->sin_len != sizeof(struct sockaddr_in) ||
            addr->sin_family != AF_INET)
                deleteAny = true;
        else
                deleteAny = false;

        iaIsLast = true;
        ia = NULL;
        IF_ADDR_WLOCK(ifp);
        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                struct in_ifaddr *it;

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

                it = (struct in_ifaddr *)ifa;
                if (deleteAny && ia == NULL && (cred == NULL ||
                    prison_check_ip4(cred, &it->ia_addr.sin_addr) == 0))
                        ia = it;

                if (it->ia_addr.sin_addr.s_addr == addr->sin_addr.s_addr &&
                    (cred == NULL || prison_check_ip4(cred,
                    &addr->sin_addr) == 0))
                        ia = it;

                if (it != ia)
                        iaIsLast = false;
        }

        if (ia == NULL) {
                IF_ADDR_WUNLOCK(ifp);
                return (EADDRNOTAVAIL);
        }

        CK_STAILQ_REMOVE(&ifp->if_addrhead, &ia->ia_ifa, ifaddr, ifa_link);
        IF_ADDR_WUNLOCK(ifp);
        ifa_free(&ia->ia_ifa);          /* if_addrhead */

        sx_assert(&in_control_sx, SA_XLOCKED);
        CK_STAILQ_REMOVE(&V_in_ifaddrhead, ia, in_ifaddr, ia_link);
        CK_LIST_REMOVE(ia, ia_hash);

        /*
         * in_scrubprefix() kills the interface route.
         */
        in_scrubprefix(ia, LLE_STATIC);

        /*
         * in_ifadown gets rid of all the rest of
         * the routes.  This is not quite the right
         * thing to do, but at least if we are running
         * a routing process they will come back.
         */
        in_ifadown(&ia->ia_ifa, 1);

        if (ia->ia_ifa.ifa_carp)
                (*carp_detach_p)(&ia->ia_ifa, cmd == SIOCAIFADDR);

        /*
         * If this is the last IPv4 address configured on this
         * interface, leave the all-hosts group.
         * No state-change report need be transmitted.
         */
        if (iaIsLast && (ifp->if_flags & IFF_MULTICAST)) {
                struct in_ifinfo *ii;

                ii = (struct in_ifinfo *)ifp->if_inet;
                if (ii->ii_allhosts) {
                        (void)in_leavegroup(ii->ii_allhosts, NULL);
                        ii->ii_allhosts = NULL;
                }
        }

        IF_ADDR_WLOCK(ifp);
        if (callout_stop(&ia->ia_garp_timer) == 1) {
                ifa_free(&ia->ia_ifa);
        }
        IF_ADDR_WUNLOCK(ifp);

        EVENTHANDLER_INVOKE(ifaddr_event_ext, ifp, &ia->ia_ifa,
            IFADDR_EVENT_DEL);
        ifa_free(&ia->ia_ifa);          /* in_ifaddrhead */

        return (0);
}

static int
in_gifaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct ucred *cred)
{
        struct in_aliasreq *ifra = (struct in_aliasreq *)data;
        const struct sockaddr_in *addr = &ifra->ifra_addr;
        struct epoch_tracker et;
        struct ifaddr *ifa;
        struct in_ifaddr *ia;

        /*
         * ifra_addr must be present and be of INET family.
         */
        if (addr->sin_len != sizeof(struct sockaddr_in) ||
            addr->sin_family != AF_INET)
                return (EINVAL);

        /*
         * See whether address exist.
         */
        ia = NULL;
        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                struct in_ifaddr *it;

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

                it = (struct in_ifaddr *)ifa;
                if (it->ia_addr.sin_addr.s_addr == addr->sin_addr.s_addr &&
                    prison_check_ip4(cred, &addr->sin_addr) == 0) {
                        ia = it;
                        break;
                }
        }
        if (ia == NULL) {
                NET_EPOCH_EXIT(et);
                return (EADDRNOTAVAIL);
        }

        ifra->ifra_mask = ia->ia_sockmask;
        if ((ifp->if_flags & IFF_POINTOPOINT) &&
            ia->ia_dstaddr.sin_family == AF_INET)
                ifra->ifra_dstaddr = ia->ia_dstaddr;
        else if ((ifp->if_flags & IFF_BROADCAST) &&
            ia->ia_broadaddr.sin_family == AF_INET)
                ifra->ifra_broadaddr = ia->ia_broadaddr;
        else
                memset(&ifra->ifra_broadaddr, 0,
                    sizeof(ifra->ifra_broadaddr));

        NET_EPOCH_EXIT(et);
        return (0);
}

static int
in_match_ifaddr(const struct rtentry *rt, const struct nhop_object *nh, void *arg)
{

        if (nh->nh_ifa == (struct ifaddr *)arg)
                return (1);

        return (0);
}

static int
in_handle_prefix_route(uint32_t fibnum, int cmd,
    struct sockaddr_in *dst, struct sockaddr_in *netmask, struct ifaddr *ifa,
    struct ifnet *ifp)
{

        NET_EPOCH_ASSERT();

        /* Prepare gateway */
        struct sockaddr_dl_short sdl = {
                .sdl_family = AF_LINK,
                .sdl_len = sizeof(struct sockaddr_dl_short),
                .sdl_type = ifa->ifa_ifp->if_type,
                .sdl_index = ifa->ifa_ifp->if_index,
        };

        struct rt_addrinfo info = {
                .rti_ifa = ifa,
                .rti_ifp = ifp,
                .rti_flags = RTF_PINNED | ((netmask != NULL) ? 0 : RTF_HOST),
                .rti_info = {
                        [RTAX_DST] = (struct sockaddr *)dst,
                        [RTAX_NETMASK] = (struct sockaddr *)netmask,
                        [RTAX_GATEWAY] = (struct sockaddr *)&sdl,
                },
                /* Ensure we delete the prefix IFF prefix ifa matches */
                .rti_filter = in_match_ifaddr,
                .rti_filterdata = ifa,
        };

        return (rib_handle_ifaddr_info(fibnum, cmd, &info));
}

/*
 * Routing table interaction with interface addresses.
 *
 * In general, two types of routes needs to be installed:
 * a) "interface" or "prefix" route, telling user that the addresses
 *   behind the ifa prefix are reached directly.
 * b) "loopback" route installed for the ifa address, telling user that
 *   the address belongs to local system.
 *
 * Handling for (a) and (b) differs in multi-fib aspects, hence they
 *  are implemented in different functions below.
 *
 * The cases above may intersect - /32 interface aliases results in
 *  the same prefix produced by (a) and (b). This blurs the definition
 *  of the "loopback" route and complicate interactions. The interaction
 *  table is defined below. The case numbers are used in the multiple
 *  functions below to refer to the particular test case.
 *
 * There can be multiple options:
 * 1) Adding address with prefix on non-p2p/non-loopback interface.
 *  Example: 192.0.2.1/24. Action:
 *  * add "prefix" route towards 192.0.2.0/24 via @ia interface,
 *    using @ia as an address source.
 *  * add "loopback" route towards 192.0.2.1 via V_loif, saving
 *   @ia ifp in the gateway and using @ia as an address source.
 *
 * 2) Adding address with /32 mask to non-p2p/non-loopback interface.
 *  Example: 192.0.2.2/32. Action:
 *  * add "prefix" host route via V_loif, using @ia as an address source.
 *
 * 3) Adding address with or without prefix to p2p interface.
 *  Example: 10.0.0.1/24->10.0.0.2. Action:
 *  * add "prefix" host route towards 10.0.0.2 via this interface, using @ia
 *    as an address source. Note: no sense in installing full /24 as the interface
 *    is point-to-point.
 *  * add "loopback" route towards 10.0.9.1 via V_loif, saving
 *   @ia ifp in the gateway and using @ia as an address source.
 *
 * 4) Adding address with or without prefix to loopback interface.
 *  Example: 192.0.2.1/24. Action:
 *  * add "prefix" host route via @ia interface, using @ia as an address source.
 *    Note: Skip installing /24 prefix as it would introduce TTL loop
 *    for the traffic destined to these addresses.
 */

/*
 * Checks if @ia needs to install loopback route to @ia address via
 *  ifa_maintain_loopback_route().
 *
 * Return true on success.
 */
static bool
ia_need_loopback_route(const struct in_ifaddr *ia)
{
        struct ifnet *ifp = ia->ia_ifp;

        /* Case 4: Skip loopback interfaces */
        if ((ifp->if_flags & IFF_LOOPBACK) ||
            (ia->ia_addr.sin_addr.s_addr == INADDR_ANY))
                return (false);

        /* Clash avoidance: Skip p2p interfaces with both addresses are equal */
        if ((ifp->if_flags & IFF_POINTOPOINT) &&
            ia->ia_dstaddr.sin_addr.s_addr == ia->ia_addr.sin_addr.s_addr)
                return (false);

        /* Case 2: skip /32 prefixes */
        if (!(ifp->if_flags & IFF_POINTOPOINT) &&
            (ia->ia_sockmask.sin_addr.s_addr == INADDR_BROADCAST))
                return (false);

        return (true);
}

/*
 * Calculate "prefix" route corresponding to @ia.
 */
static void
ia_getrtprefix(const struct in_ifaddr *ia, struct in_addr *prefix, struct in_addr *mask)
{

        if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) {
                /* Case 3: return host route for dstaddr */
                *prefix = ia->ia_dstaddr.sin_addr;
                mask->s_addr = INADDR_BROADCAST;
        } else if (ia->ia_ifp->if_flags & IFF_LOOPBACK) {
                /* Case 4: return host route for ifaddr */
                *prefix = ia->ia_addr.sin_addr;
                mask->s_addr = INADDR_BROADCAST;
        } else {
                /* Cases 1,2: return actual ia prefix */
                *prefix = ia->ia_addr.sin_addr;
                *mask = ia->ia_sockmask.sin_addr;
                prefix->s_addr &= mask->s_addr;
        }
}

/*
 * Adds or delete interface "prefix" route corresponding to @ifa.
 *  Returns 0 on success or errno.
 */
static int
in_handle_ifaddr_route(int cmd, struct in_ifaddr *ia)
{
        struct ifaddr *ifa = &ia->ia_ifa;
        struct in_addr daddr, maddr;
        struct sockaddr_in *pmask;
        struct epoch_tracker et;
        int error;

        ia_getrtprefix(ia, &daddr, &maddr);

        struct sockaddr_in mask = {
                .sin_family = AF_INET,
                .sin_len = sizeof(struct sockaddr_in),
                .sin_addr = maddr,
        };

        pmask = (maddr.s_addr != INADDR_BROADCAST) ? &mask : NULL;

        struct sockaddr_in dst = {
                .sin_family = AF_INET,
                .sin_len = sizeof(struct sockaddr_in),
                .sin_addr.s_addr = daddr.s_addr & maddr.s_addr,
        };

        struct ifnet *ifp = ia->ia_ifp;

        if ((maddr.s_addr == INADDR_BROADCAST) &&
            (!(ia->ia_ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)))) {
                /* Case 2: host route on broadcast interface */
                ifp = V_loif;
        }

        uint32_t fibnum = ifa->ifa_ifp->if_fib;
        NET_EPOCH_ENTER(et);
        error = in_handle_prefix_route(fibnum, cmd, &dst, pmask, ifa, ifp);
        NET_EPOCH_EXIT(et);

        return (error);
}

/*
 * Check if we have a route for the given prefix already.
 */
static bool
in_hasrtprefix(struct in_ifaddr *target)
{
        struct epoch_tracker et;
        struct in_ifaddr *ia;
        struct in_addr prefix, mask, p, m;
        bool result = false;

        ia_getrtprefix(target, &prefix, &mask);

        /* Look for an existing address with the same prefix, mask, and fib */
        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
                ia_getrtprefix(ia, &p, &m);

                if (prefix.s_addr != p.s_addr ||
                    mask.s_addr != m.s_addr)
                        continue;

                if (target->ia_ifp->if_fib != ia->ia_ifp->if_fib)
                        continue;

                /*
                 * If we got a matching prefix route inserted by other
                 * interface address, we are done here.
                 */
                if (ia->ia_flags & IFA_ROUTE) {
                        result = true;
                        break;
                }
        }
        NET_EPOCH_EXIT(et);

        return (result);
}

int
in_addprefix(struct in_ifaddr *target)
{
        int error;

        if (in_hasrtprefix(target)) {
                if (V_nosameprefix)
                        return (EEXIST);
                else {
                        rt_addrmsg(RTM_ADD, &target->ia_ifa,
                            target->ia_ifp->if_fib);
                        return (0);
                }
        }

        /*
         * No-one seem to have this prefix route, so we try to insert it.
         */
        rt_addrmsg(RTM_ADD, &target->ia_ifa, target->ia_ifp->if_fib);
        error = in_handle_ifaddr_route(RTM_ADD, target);
        if (!error)
                target->ia_flags |= IFA_ROUTE;
        return (error);
}

/*
 * Removes either all lle entries for given @ia, or lle
 * corresponding to @ia address.
 */
static void
in_scrubprefixlle(struct in_ifaddr *ia, int all, u_int flags)
{
        struct sockaddr_in addr, mask;
        struct sockaddr *saddr, *smask;
        struct ifnet *ifp;

        saddr = (struct sockaddr *)&addr;
        bzero(&addr, sizeof(addr));
        addr.sin_len = sizeof(addr);
        addr.sin_family = AF_INET;
        smask = (struct sockaddr *)&mask;
        bzero(&mask, sizeof(mask));
        mask.sin_len = sizeof(mask);
        mask.sin_family = AF_INET;
        mask.sin_addr.s_addr = ia->ia_subnetmask;
        ifp = ia->ia_ifp;

        if (all) {
                /*
                 * Remove all L2 entries matching given prefix.
                 * Convert address to host representation to avoid
                 * doing this on every callback. ia_subnetmask is already
                 * stored in host representation.
                 */
                addr.sin_addr.s_addr = ntohl(ia->ia_addr.sin_addr.s_addr);
                lltable_prefix_free(AF_INET, saddr, smask, flags);
        } else {
                /* Remove interface address only */
                addr.sin_addr.s_addr = ia->ia_addr.sin_addr.s_addr;
                lltable_delete_addr(LLTABLE(ifp), LLE_IFADDR, saddr);
        }
}

/*
 * If there is no other address in the system that can serve a route to the
 * same prefix, remove the route.  Hand over the route to the new address
 * otherwise.
 */
int
in_scrubprefix(struct in_ifaddr *target, u_int flags)
{
        struct epoch_tracker et;
        struct in_ifaddr *ia;
        struct in_addr prefix, mask, p, m;
        int error = 0;

        /*
         * Remove the loopback route to the interface address.
         */
        if (ia_need_loopback_route(target) && (flags & LLE_STATIC)) {
                struct in_ifaddr *eia;

                eia = in_localip_more(target);

                if (eia != NULL) {
                        error = ifa_switch_loopback_route((struct ifaddr *)eia,
                            (struct sockaddr *)&target->ia_addr);
                        ifa_free(&eia->ia_ifa);
                } else {
                        error = ifa_del_loopback_route((struct ifaddr *)target,
                            (struct sockaddr *)&target->ia_addr);
                }
        }

        ia_getrtprefix(target, &prefix, &mask);

        if ((target->ia_flags & IFA_ROUTE) == 0) {
                rt_addrmsg(RTM_DELETE, &target->ia_ifa, target->ia_ifp->if_fib);

                /*
                 * Removing address from !IFF_UP interface or
                 * prefix which exists on other interface (along with route).
                 * No entries should exist here except target addr.
                 * Given that, delete this entry only.
                 */
                in_scrubprefixlle(target, 0, flags);
                return (0);
        }

        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
                ia_getrtprefix(ia, &p, &m);

                if (prefix.s_addr != p.s_addr ||
                    mask.s_addr != m.s_addr)
                        continue;

                if ((ia->ia_ifp->if_flags & IFF_UP) == 0)
                        continue;

                /*
                 * If we got a matching prefix address, move IFA_ROUTE and
                 * the route itself to it.  Make sure that routing daemons
                 * get a heads-up.
                 */
                if ((ia->ia_flags & IFA_ROUTE) == 0) {
                        ifa_ref(&ia->ia_ifa);
                        NET_EPOCH_EXIT(et);
                        error = in_handle_ifaddr_route(RTM_DELETE, target);
                        if (error == 0)
                                target->ia_flags &= ~IFA_ROUTE;
                        else
                                log(LOG_INFO, "in_scrubprefix: err=%d, old prefix delete failed\n",
                                        error);
                        /* Scrub all entries IFF interface is different */
                        in_scrubprefixlle(target, target->ia_ifp != ia->ia_ifp,
                            flags);
                        error = in_handle_ifaddr_route(RTM_ADD, ia);
                        if (error == 0)
                                ia->ia_flags |= IFA_ROUTE;
                        else
                                log(LOG_INFO, "in_scrubprefix: err=%d, new prefix add failed\n",
                                        error);
                        ifa_free(&ia->ia_ifa);
                        return (error);
                }
        }
        NET_EPOCH_EXIT(et);

        /*
         * remove all L2 entries on the given prefix
         */
        in_scrubprefixlle(target, 1, flags);

        /*
         * As no-one seem to have this prefix, we can remove the route.
         */
        rt_addrmsg(RTM_DELETE, &target->ia_ifa, target->ia_ifp->if_fib);
        error = in_handle_ifaddr_route(RTM_DELETE, target);
        if (error == 0)
                target->ia_flags &= ~IFA_ROUTE;
        else
                log(LOG_INFO, "in_scrubprefix: err=%d, prefix delete failed\n", error);
        return (error);
}

void
in_ifscrub_all(void)
{
        struct ifnet *ifp;
        struct ifaddr *ifa, *nifa;
        struct ifreq ifr;

        IFNET_RLOCK();
        CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                /* Cannot lock here - lock recursion. */
                /* NET_EPOCH_ENTER(et); */
                CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;

                        /*
                         * This is ugly but the only way for legacy IP to
                         * cleanly remove addresses and everything attached.
                         */
                        bzero(&ifr, sizeof(ifr));
                        ifr.ifr_addr = *ifa->ifa_addr;
                        (void)in_control(NULL, SIOCDIFADDR, (caddr_t)&ifr,
                            ifp, NULL);
                }
                /* NET_EPOCH_EXIT(et); */
                in_purgemaddrs(ifp);
                igmp_domifdetach(ifp);
        }
        IFNET_RUNLOCK();
}

bool
in_ifaddr_broadcast(struct in_addr in, struct in_ifaddr *ia)
{

        return ((in.s_addr == ia->ia_broadaddr.sin_addr.s_addr ||
             /*
              * Optionally check for old-style (host 0) broadcast, but
              * taking into account that RFC 3021 obsoletes it.
              */
            __predict_false(V_broadcast_lowest &&
            ia->ia_subnetmask != IN_RFC3021_MASK &&
            ntohl(in.s_addr) == ia->ia_subnet)) &&
             /*
              * Check for an all one subnetmask. These
              * only exist when an interface gets a secondary
              * address.
              */
            ia->ia_subnetmask != (u_long)0xffffffff);
}

/*
 * Return true if the address might be a local broadcast address.
 */
bool
in_ifnet_broadcast(struct in_addr in, struct ifnet *ifp)
{
        struct ifaddr *ifa;

        NET_EPOCH_ASSERT();

        if (in_broadcast(in))
                return (true);
        if ((ifp->if_flags & IFF_BROADCAST) == 0)
                return (false);
        /*
         * Look through the list of addresses for a match
         * with a broadcast address.
         */
        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
                if (ifa->ifa_addr->sa_family == AF_INET &&
                    in_ifaddr_broadcast(in, (struct in_ifaddr *)ifa))
                        return (true);
        return (false);
}


static struct lltable *in_lltattach(struct ifnet *);
void
in_ifattach(void *arg __unused, struct ifnet *ifp)
{
        struct in_ifinfo *ii;

        ii = malloc(sizeof(struct in_ifinfo), M_IFADDR, M_WAITOK|M_ZERO);
        ii->ii_llt = in_lltattach(ifp);
        ii->ii_igmp = igmp_domifattach(ifp);
        ifp->if_inet = ii;
}
EVENTHANDLER_DEFINE(ifnet_arrival_event, in_ifattach, NULL,
    EVENTHANDLER_PRI_ANY);

/*
 * On interface removal, clean up IPv4 data structures hung off of the ifnet.
 */
static void
in_ifdetach(void *arg __unused, struct ifnet *ifp)
{
        struct in_ifinfo *ii = ifp->if_inet;

#ifdef VIMAGE
        /*
         * On VNET shutdown abort here as the stack teardown will do all
         * the work top-down for us.  XXXGL: this logic is copied from
         * if_detach() before dom_ifattach removal.  Ideally we'd like to have
         * same logic for VNET shutdown and normal detach.  This means that
         * interfaces should be detach before protocols destroyed during VNET
         * shutdown.
         */
        if (!VNET_IS_SHUTTING_DOWN(ifp->if_vnet))
#endif
        {
                IN_MULTI_LOCK();
                in_pcbpurgeif0(&V_ripcbinfo, ifp);
                in_pcbpurgeif0(&V_udbinfo, ifp);
                in_pcbpurgeif0(&V_ulitecbinfo, ifp);
                in_purgemaddrs(ifp);
                IN_MULTI_UNLOCK();

                /*
                 * Make sure all multicast deletions invoking if_ioctl() are
                 * completed before returning. Else we risk accessing a freed
                 * ifnet structure pointer.
                 */
                inm_release_wait(NULL);
        }

        igmp_domifdetach(ifp);
        lltable_free(ii->ii_llt);
        free(ii, M_IFADDR);
}
EVENTHANDLER_DEFINE(ifnet_departure_event, in_ifdetach, NULL,
    EVENTHANDLER_PRI_ANY);

static void
in_ifnet_event(void *arg __unused, struct ifnet *ifp, int event)
{
        struct epoch_tracker et;
        struct ifaddr *ifa;
        struct in_ifaddr *ia;
        int error;

        NET_EPOCH_ENTER(et);
        switch (event) {
        case IFNET_EVENT_DOWN:
                CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;
                        ia = (struct in_ifaddr *)ifa;
                        if ((ia->ia_flags & IFA_ROUTE) == 0)
                                continue;
                        ifa_ref(ifa);
                        /*
                         * in_scrubprefix() kills the interface route.
                         */
                        in_scrubprefix(ia, 0);
                        /*
                         * in_ifadown gets rid of all the rest of the
                         * routes.  This is not quite the right thing
                         * to do, but at least if we are running a
                         * routing process they will come back.
                         */
                        in_ifadown(ifa, 0);
                        ifa_free(ifa);
                }
                break;

        case IFNET_EVENT_UP:
                CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;
                        ia = (struct in_ifaddr *)ifa;
                        if (ia->ia_flags & IFA_ROUTE)
                                continue;
                        ifa_ref(ifa);
                        error = ifa_del_loopback_route(ifa, ifa->ifa_addr);
                        rt_addrmsg(RTM_ADD, ifa, ifa->ifa_ifp->if_fib);
                        error = in_handle_ifaddr_route(RTM_ADD, ia);
                        if (error == 0)
                                ia->ia_flags |= IFA_ROUTE;
                        error = ifa_add_loopback_route(ifa, ifa->ifa_addr);
                        ifa_free(ifa);
                }
                break;
        }
        NET_EPOCH_EXIT(et);
}
EVENTHANDLER_DEFINE(ifnet_event, in_ifnet_event, NULL, EVENTHANDLER_PRI_ANY);

/*
 * Delete all IPv4 multicast address records, and associated link-layer
 * multicast address records, associated with ifp.
 * XXX It looks like domifdetach runs AFTER the link layer cleanup.
 * XXX This should not race with ifma_protospec being set during
 * a new allocation, if it does, we have bigger problems.
 */
static void
in_purgemaddrs(struct ifnet *ifp)
{
        struct epoch_tracker     et;
        struct in_multi_head purgeinms;
        struct in_multi         *inm;
        struct ifmultiaddr      *ifma;

        SLIST_INIT(&purgeinms);
        IN_MULTI_LIST_LOCK();

        /*
         * Extract list of in_multi associated with the detaching ifp
         * which the PF_INET layer is about to release.
         * We need to do this as IF_ADDR_LOCK() may be re-acquired
         * by code further down.
         */
        IF_ADDR_WLOCK(ifp);
        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                inm = inm_ifmultiaddr_get_inm(ifma);
                if (inm == NULL)
                        continue;
                inm_rele_locked(&purgeinms, inm);
        }
        NET_EPOCH_EXIT(et);
        IF_ADDR_WUNLOCK(ifp);

        inm_release_list_deferred(&purgeinms);
        igmp_ifdetach(ifp);
        IN_MULTI_LIST_UNLOCK();
}

struct in_llentry {
        struct llentry          base;
};

#define IN_LLTBL_DEFAULT_HSIZE  32
#define IN_LLTBL_HASH(k, h) \
        (((((((k >> 8) ^ k) >> 8) ^ k) >> 8) ^ k) & ((h) - 1))

/*
 * Do actual deallocation of @lle.
 */
static void
in_lltable_destroy_lle_unlocked(epoch_context_t ctx)
{
        struct llentry *lle;

        lle = __containerof(ctx, struct llentry, lle_epoch_ctx);
        LLE_LOCK_DESTROY(lle);
        LLE_REQ_DESTROY(lle);
        free(lle, M_LLTABLE);
}

/*
 * Called by LLE_FREE_LOCKED when number of references
 * drops to zero.
 */
static void
in_lltable_destroy_lle(struct llentry *lle)
{

        LLE_WUNLOCK(lle);
        NET_EPOCH_CALL(in_lltable_destroy_lle_unlocked, &lle->lle_epoch_ctx);
}

static struct llentry *
in_lltable_new(struct in_addr addr4, u_int flags)
{
        struct in_llentry *lle;

        lle = malloc(sizeof(struct in_llentry), M_LLTABLE, M_NOWAIT | M_ZERO);
        if (lle == NULL)                /* NB: caller generates msg */
                return NULL;

        /*
         * For IPv4 this will trigger "arpresolve" to generate
         * an ARP request.
         */
        lle->base.la_expire = time_uptime; /* mark expired */
        lle->base.r_l3addr.addr4 = addr4;
        lle->base.lle_refcnt = 1;
        lle->base.lle_free = in_lltable_destroy_lle;
        LLE_LOCK_INIT(&lle->base);
        LLE_REQ_INIT(&lle->base);
        callout_init(&lle->base.lle_timer, 1);

        return (&lle->base);
}

static int
in_lltable_match_prefix(const struct sockaddr *saddr,
    const struct sockaddr *smask, u_int flags, struct llentry *lle)
{
        struct in_addr addr, mask, lle_addr;

        addr = ((const struct sockaddr_in *)saddr)->sin_addr;
        mask = ((const struct sockaddr_in *)smask)->sin_addr;
        lle_addr.s_addr = ntohl(lle->r_l3addr.addr4.s_addr);

        if (IN_ARE_MASKED_ADDR_EQUAL(lle_addr, addr, mask) == 0)
                return (0);

        if (lle->la_flags & LLE_IFADDR) {
                /*
                 * Delete LLE_IFADDR records IFF address & flag matches.
                 * Note that addr is the interface address within prefix
                 * being matched.
                 * Note also we should handle 'ifdown' cases without removing
                 * ifaddr macs.
                 */
                if (addr.s_addr == lle_addr.s_addr && (flags & LLE_STATIC) != 0)
                        return (1);
                return (0);
        }

        /* flags & LLE_STATIC means deleting both dynamic and static entries */
        if ((flags & LLE_STATIC) || !(lle->la_flags & LLE_STATIC))
                return (1);

        return (0);
}

static void
in_lltable_free_entry(struct lltable *llt, struct llentry *lle)
{
        size_t pkts_dropped;

        LLE_WLOCK_ASSERT(lle);
        KASSERT(llt != NULL, ("lltable is NULL"));

        /* Unlink entry from table if not already */
        if ((lle->la_flags & LLE_LINKED) != 0) {
                LLTABLE_LOCK_ASSERT(llt);
                lltable_unlink_entry(llt, lle);
        }

        /* Drop hold queue */
        pkts_dropped = llentry_free(lle);
        ARPSTAT_ADD(dropped, pkts_dropped);
}

static int
in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr)
{
        struct nhop_object *nh;
        struct in_addr addr;

        KASSERT(l3addr->sa_family == AF_INET,
            ("sin_family %d", l3addr->sa_family));

        addr = ((const struct sockaddr_in *)l3addr)->sin_addr;

        nh = fib4_lookup(ifp->if_fib, addr, 0, NHR_NONE, 0);
        if (nh == NULL)
                return (EINVAL);

        /*
         * If the gateway for an existing host route matches the target L3
         * address, which is a special route inserted by some implementation
         * such as MANET, and the interface is of the correct type, then
         * allow for ARP to proceed.
         */
        if (nh->nh_flags & NHF_GATEWAY) {
                if (!(nh->nh_flags & NHF_HOST) || nh->nh_ifp->if_type != IFT_ETHER ||
                    (nh->nh_ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) != 0 ||
                    memcmp(nh->gw_sa.sa_data, l3addr->sa_data,
                    sizeof(in_addr_t)) != 0) {
                        return (EINVAL);
                }
        }

        /*
         * Make sure that at least the destination address is covered
         * by the route. This is for handling the case where 2 or more
         * interfaces have the same prefix. An incoming packet arrives
         * on one interface and the corresponding outgoing packet leaves
         * another interface.
         */
        if ((nh->nh_ifp != ifp) && (nh->nh_flags & NHF_HOST) == 0) {
                struct in_ifaddr *ia = (struct in_ifaddr *)ifaof_ifpforaddr(l3addr, ifp);
                struct in_addr dst_addr, mask_addr;

                if (ia == NULL)
                        return (EINVAL);

                /*
                 * ifaof_ifpforaddr() returns _best matching_ IFA.
                 * It is possible that ifa prefix does not cover our address.
                 * Explicitly verify and fail if that's the case.
                 */
                dst_addr = IA_SIN(ia)->sin_addr;
                mask_addr.s_addr = htonl(ia->ia_subnetmask);

                if (!IN_ARE_MASKED_ADDR_EQUAL(dst_addr, addr, mask_addr))
                        return (EINVAL);
        }

        return (0);
}

static inline uint32_t
in_lltable_hash_dst(const struct in_addr dst, uint32_t hsize)
{

        return (IN_LLTBL_HASH(dst.s_addr, hsize));
}

static uint32_t
in_lltable_hash(const struct llentry *lle, uint32_t hsize)
{

        return (in_lltable_hash_dst(lle->r_l3addr.addr4, hsize));
}

static void
in_lltable_fill_sa_entry(const struct llentry *lle, struct sockaddr *sa)
{
        struct sockaddr_in *sin;

        sin = (struct sockaddr_in *)sa;
        bzero(sin, sizeof(*sin));
        sin->sin_family = AF_INET;
        sin->sin_len = sizeof(*sin);
        sin->sin_addr = lle->r_l3addr.addr4;
}

static inline struct llentry *
in_lltable_find_dst(struct lltable *llt, struct in_addr dst)
{
        struct llentry *lle;
        struct llentries *lleh;
        u_int hashidx;

        hashidx = in_lltable_hash_dst(dst, llt->llt_hsize);
        lleh = &llt->lle_head[hashidx];
        CK_LIST_FOREACH(lle, lleh, lle_next) {
                if (lle->la_flags & LLE_DELETED)
                        continue;
                if (lle->r_l3addr.addr4.s_addr == dst.s_addr)
                        break;
        }

        return (lle);
}

static void
in_lltable_delete_entry(struct lltable *llt, struct llentry *lle)
{

        lle->la_flags |= LLE_DELETED;
        EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_DELETED);
#ifdef DIAGNOSTIC
        log(LOG_INFO, "ifaddr cache = %p is deleted\n", lle);
#endif
        llentry_free(lle);
}

static struct llentry *
in_lltable_alloc(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
{
        const struct sockaddr_in *sin = (const struct sockaddr_in *)l3addr;
        struct ifnet *ifp = llt->llt_ifp;
        struct llentry *lle;
        char linkhdr[LLE_MAX_LINKHDR];
        size_t linkhdrsize;
        int lladdr_off;

        KASSERT(l3addr->sa_family == AF_INET,
            ("sin_family %d", l3addr->sa_family));

        /*
         * A route that covers the given address must have
         * been installed 1st because we are doing a resolution,
         * verify this.
         */
        if (!(flags & LLE_IFADDR) &&
            in_lltable_rtcheck(ifp, flags, l3addr) != 0)
                return (NULL);

        lle = in_lltable_new(sin->sin_addr, flags);
        if (lle == NULL) {
                log(LOG_INFO, "lla_lookup: new lle malloc failed\n");
                return (NULL);
        }
        lle->la_flags = flags;
        if (flags & LLE_STATIC)
                lle->r_flags |= RLLE_VALID;
        if ((flags & LLE_IFADDR) == LLE_IFADDR) {
                linkhdrsize = LLE_MAX_LINKHDR;
                if (lltable_calc_llheader(ifp, AF_INET, IF_LLADDR(ifp),
                    linkhdr, &linkhdrsize, &lladdr_off) != 0) {
                        in_lltable_free_entry(llt, lle);
                        return (NULL);
                }
                lltable_set_entry_addr(ifp, lle, linkhdr, linkhdrsize,
                    lladdr_off);
                lle->la_flags |= LLE_STATIC;
                lle->r_flags |= (RLLE_VALID | RLLE_IFADDR);
                lle->la_expire = 0;
        }

        return (lle);
}

/*
 * Return NULL if not found or marked for deletion.
 * If found return lle read locked.
 */
static struct llentry *
in_lltable_lookup(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
{
        const struct sockaddr_in *sin = (const struct sockaddr_in *)l3addr;
        struct llentry *lle;

        LLTABLE_RLOCK_ASSERT(llt);
        KASSERT(l3addr->sa_family == AF_INET,
            ("sin_family %d", l3addr->sa_family));
        KASSERT((flags & (LLE_UNLOCKED | LLE_EXCLUSIVE)) !=
            (LLE_UNLOCKED | LLE_EXCLUSIVE),
            ("wrong lle request flags: %#x", flags));

        lle = in_lltable_find_dst(llt, sin->sin_addr);
        if (lle == NULL)
                return (NULL);
        if (flags & LLE_UNLOCKED)
                return (lle);

        if (flags & LLE_EXCLUSIVE)
                LLE_WLOCK(lle);
        else
                LLE_RLOCK(lle);

        /*
         * If the afdata lock is not held, the LLE may have been unlinked while
         * we were blocked on the LLE lock.  Check for this case.
         */
        if (__predict_false((lle->la_flags & LLE_LINKED) == 0)) {
                if (flags & LLE_EXCLUSIVE)
                        LLE_WUNLOCK(lle);
                else
                        LLE_RUNLOCK(lle);
                return (NULL);
        }
        return (lle);
}

static int
in_lltable_dump_entry(struct lltable *llt, struct llentry *lle,
    struct sysctl_req *wr)
{
        struct ifnet *ifp = llt->llt_ifp;
        /* XXX stack use */
        struct {
                struct rt_msghdr        rtm;
                struct sockaddr_in      sin;
                struct sockaddr_dl      sdl;
        } arpc;
        struct sockaddr_dl *sdl;
        int error;

        bzero(&arpc, sizeof(arpc));
        /* skip deleted entries */
        if ((lle->la_flags & LLE_DELETED) == LLE_DELETED)
                return (0);
        /* Skip if jailed and not a valid IP of the prison. */
        lltable_fill_sa_entry(lle,(struct sockaddr *)&arpc.sin);
        if (prison_if(wr->td->td_ucred, (struct sockaddr *)&arpc.sin) != 0)
                return (0);
        /*
         * produce a msg made of:
         *  struct rt_msghdr;
         *  struct sockaddr_in; (IPv4)
         *  struct sockaddr_dl;
         */
        arpc.rtm.rtm_msglen = sizeof(arpc);
        arpc.rtm.rtm_version = RTM_VERSION;
        arpc.rtm.rtm_type = RTM_GET;
        arpc.rtm.rtm_flags = RTF_UP;
        arpc.rtm.rtm_addrs = RTA_DST | RTA_GATEWAY;

        /* publish */
        if (lle->la_flags & LLE_PUB)
                arpc.rtm.rtm_flags |= RTF_ANNOUNCE;

        sdl = &arpc.sdl;
        sdl->sdl_family = AF_LINK;
        sdl->sdl_len = sizeof(*sdl);
        sdl->sdl_index = ifp->if_index;
        sdl->sdl_type = ifp->if_type;
        if ((lle->la_flags & LLE_VALID) == LLE_VALID) {
                sdl->sdl_alen = ifp->if_addrlen;
                bcopy(lle->ll_addr, LLADDR(sdl), ifp->if_addrlen);
        } else {
                sdl->sdl_alen = 0;
                bzero(LLADDR(sdl), ifp->if_addrlen);
        }

        arpc.rtm.rtm_rmx.rmx_expire =
            lle->la_flags & LLE_STATIC ? 0 : lle->la_expire;
        arpc.rtm.rtm_flags |= (RTF_HOST | RTF_LLDATA);
        if (lle->la_flags & LLE_STATIC)
                arpc.rtm.rtm_flags |= RTF_STATIC;
        if (lle->la_flags & LLE_IFADDR)
                arpc.rtm.rtm_flags |= RTF_PINNED;
        arpc.rtm.rtm_index = ifp->if_index;
        error = SYSCTL_OUT(wr, &arpc, sizeof(arpc));

        return (error);
}

static void
in_lltable_post_resolved(struct lltable *llt, struct llentry *lle)
{
        struct ifnet *ifp = llt->llt_ifp;

        /* gratuitous ARP */
        if ((lle->la_flags & LLE_PUB) != 0)
                arprequest(ifp, &lle->r_l3addr.addr4, &lle->r_l3addr.addr4,
                    lle->ll_addr);
}

static struct lltable *
in_lltattach(struct ifnet *ifp)
{
        struct lltable *llt;

        llt = lltable_allocate_htbl(IN_LLTBL_DEFAULT_HSIZE);
        llt->llt_af = AF_INET;
        llt->llt_ifp = ifp;

        llt->llt_lookup = in_lltable_lookup;
        llt->llt_alloc_entry = in_lltable_alloc;
        llt->llt_delete_entry = in_lltable_delete_entry;
        llt->llt_dump_entry = in_lltable_dump_entry;
        llt->llt_hash = in_lltable_hash;
        llt->llt_fill_sa_entry = in_lltable_fill_sa_entry;
        llt->llt_free_entry = in_lltable_free_entry;
        llt->llt_match_prefix = in_lltable_match_prefix;
        llt->llt_mark_used = llentry_mark_used;
        llt->llt_post_resolved = in_lltable_post_resolved;
        lltable_link(llt);

        return (llt);
}

struct lltable *
in_lltable_get(struct ifnet *ifp)
{
        /* XXXGL: ??? */
        if (ifp->if_inet == NULL)
                return (NULL);

        return (((struct in_ifinfo *)ifp->if_inet)->ii_llt);
}