xnu-3789.31.2.tar.gz

[apple/xnu.git] / bsd / net / route.c

/*
 * Copyright (c) 2000-2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1980, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 *      @(#)route.c     8.2 (Berkeley) 11/15/93
 * $FreeBSD: src/sys/net/route.c,v 1.59.2.3 2001/07/29 19:18:02 ume Exp $
 */

#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/domain.h>
#include <sys/stat.h>
#include <sys/ubc.h>
#include <sys/vnode.h>
#include <sys/syslog.h>
#include <sys/queue.h>
#include <sys/mcache.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <kern/locks.h>
#include <kern/zalloc.h>

#include <net/dlil.h>
#include <net/if.h>
#include <net/route.h>
#include <net/ntstat.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>

#if INET6
#include <netinet6/ip6_var.h>
#include <netinet6/in6_var.h>
#include <netinet6/nd6.h>
#endif /* INET6 */

#include <net/if_dl.h>

#include <libkern/OSAtomic.h>
#include <libkern/OSDebug.h>

#include <pexpert/pexpert.h>

#if CONFIG_MACF
#include <sys/kauth.h>
#endif

/*
 * Synchronization notes:
 *
 * Routing entries fall under two locking domains: the global routing table
 * lock (rnh_lock) and the per-entry lock (rt_lock); the latter is a mutex that
 * resides (statically defined) in the rtentry structure.
 *
 * The locking domains for routing are defined as follows:
 *
 * The global routing lock is used to serialize all accesses to the radix
 * trees defined by rt_tables[], as well as the tree of masks.  This includes
 * lookups, insertions and removals of nodes to/from the respective tree.
 * It is also used to protect certain fields in the route entry that aren't
 * often modified and/or require global serialization (more details below.)
 *
 * The per-route entry lock is used to serialize accesses to several routing
 * entry fields (more details below.)  Acquiring and releasing this lock is
 * done via RT_LOCK() and RT_UNLOCK() routines.
 *
 * In cases where both rnh_lock and rt_lock must be held, the former must be
 * acquired first in order to maintain lock ordering.  It is not a requirement
 * that rnh_lock be acquired first before rt_lock, but in case both must be
 * acquired in succession, the correct lock ordering must be followed.
 *
 * The fields of the rtentry structure are protected in the following way:
 *
 * rt_nodes[]
 *
 *      - Routing table lock (rnh_lock).
 *
 * rt_parent, rt_mask, rt_llinfo_free, rt_tree_genid
 *
 *      - Set once during creation and never changes; no locks to read.
 *
 * rt_flags, rt_genmask, rt_llinfo, rt_rmx, rt_refcnt, rt_gwroute
 *
 *      - Routing entry lock (rt_lock) for read/write access.
 *
 *      - Some values of rt_flags are either set once at creation time,
 *        or aren't currently used, and thus checking against them can
 *        be done without rt_lock: RTF_GATEWAY, RTF_HOST, RTF_DYNAMIC,
 *        RTF_DONE,  RTF_XRESOLVE, RTF_STATIC, RTF_BLACKHOLE, RTF_ANNOUNCE,
 *        RTF_USETRAILERS, RTF_WASCLONED, RTF_PINNED, RTF_LOCAL,
 *        RTF_BROADCAST, RTF_MULTICAST, RTF_IFSCOPE, RTF_IFREF.
 *
 * rt_key, rt_gateway, rt_ifp, rt_ifa
 *
 *      - Always written/modified with both rnh_lock and rt_lock held.
 *
 *      - May be read freely with rnh_lock held, else must hold rt_lock
 *        for read access; holding both locks for read is also okay.
 *
 *      - In the event rnh_lock is not acquired, or is not possible to be
 *        acquired across the operation, setting RTF_CONDEMNED on a route
 *        entry will prevent its rt_key, rt_gateway, rt_ifp and rt_ifa
 *        from being modified.  This is typically done on a route that
 *        has been chosen for a removal (from the tree) prior to dropping
 *        the rt_lock, so that those values will remain the same until
 *        the route is freed.
 *
 *        When rnh_lock is held rt_setgate(), rt_setif(), and rtsetifa() are
 *        single-threaded, thus exclusive.  This flag will also prevent the
 *        route from being looked up via rt_lookup().
 *
 * rt_genid
 *
 *      - Assumes that 32-bit writes are atomic; no locks.
 *
 * rt_dlt, rt_output
 *
 *      - Currently unused; no locks.
 *
 * Operations on a route entry can be described as follows:
 *
 * CREATE an entry with reference count set to 0 as part of RTM_ADD/RESOLVE.
 *
 * INSERTION of an entry into the radix tree holds the rnh_lock, checks
 * for duplicates and then adds the entry.  rtrequest returns the entry
 * after bumping up the reference count to 1 (for the caller).
 *
 * LOOKUP of an entry holds the rnh_lock and bumps up the reference count
 * before returning; it is valid to also bump up the reference count using
 * RT_ADDREF after the lookup has returned an entry.
 *
 * REMOVAL of an entry from the radix tree holds the rnh_lock, removes the
 * entry but does not decrement the reference count.  Removal happens when
 * the route is explicitly deleted (RTM_DELETE) or when it is in the cached
 * state and it expires.  The route is said to be "down" when it is no
 * longer present in the tree.  Freeing the entry will happen on the last
 * reference release of such a "down" route.
 *
 * RT_ADDREF/RT_REMREF operates on the routing entry which increments/
 * decrements the reference count, rt_refcnt, atomically on the rtentry.
 * rt_refcnt is modified only using this routine.  The general rule is to
 * do RT_ADDREF in the function that is passing the entry as an argument,
 * in order to prevent the entry from being freed by the callee.
 */

#define equal(a1, a2) (bcmp((caddr_t)(a1), (caddr_t)(a2), (a1)->sa_len) == 0)

extern void kdp_set_gateway_mac(void *gatewaymac);

__private_extern__ struct rtstat rtstat  = { 0, 0, 0, 0, 0 };
struct radix_node_head *rt_tables[AF_MAX+1];

decl_lck_mtx_data(, rnh_lock_data);     /* global routing tables mutex */
lck_mtx_t               *rnh_lock = &rnh_lock_data;
static lck_attr_t       *rnh_lock_attr;
static lck_grp_t        *rnh_lock_grp;
static lck_grp_attr_t   *rnh_lock_grp_attr;

/* Lock group and attribute for routing entry locks */
static lck_attr_t       *rte_mtx_attr;
static lck_grp_t        *rte_mtx_grp;
static lck_grp_attr_t   *rte_mtx_grp_attr;

int rttrash = 0;                /* routes not in table but not freed */

unsigned int rte_debug;

/* Possible flags for rte_debug */
#define RTD_DEBUG       0x1     /* enable or disable rtentry debug facility */
#define RTD_TRACE       0x2     /* trace alloc, free, refcnt and lock */
#define RTD_NO_FREE     0x4     /* don't free (good to catch corruptions) */

#define RTE_NAME                "rtentry"       /* name for zone and rt_lock */

static struct zone *rte_zone;                   /* special zone for rtentry */
#define RTE_ZONE_MAX            65536           /* maximum elements in zone */
#define RTE_ZONE_NAME           RTE_NAME        /* name of rtentry zone */

#define RTD_INUSE               0xFEEDFACE      /* entry is in use */
#define RTD_FREED               0xDEADBEEF      /* entry is freed */

#define MAX_SCOPE_ADDR_STR_LEN  (MAX_IPv6_STR_LEN + 6)

/* For gdb */
__private_extern__ unsigned int ctrace_stack_size = CTRACE_STACK_SIZE;
__private_extern__ unsigned int ctrace_hist_size = CTRACE_HIST_SIZE;

/*
 * Debug variant of rtentry structure.
 */
struct rtentry_dbg {
        struct rtentry  rtd_entry;                      /* rtentry */
        struct rtentry  rtd_entry_saved;                /* saved rtentry */
        uint32_t        rtd_inuse;                      /* in use pattern */
        uint16_t        rtd_refhold_cnt;                /* # of rtref */
        uint16_t        rtd_refrele_cnt;                /* # of rtunref */
        uint32_t        rtd_lock_cnt;                   /* # of locks */
        uint32_t        rtd_unlock_cnt;                 /* # of unlocks */
        /*
         * Alloc and free callers.
         */
        ctrace_t        rtd_alloc;
        ctrace_t        rtd_free;
        /*
         * Circular lists of rtref and rtunref callers.
         */
        ctrace_t        rtd_refhold[CTRACE_HIST_SIZE];
        ctrace_t        rtd_refrele[CTRACE_HIST_SIZE];
        /*
         * Circular lists of locks and unlocks.
         */
        ctrace_t        rtd_lock[CTRACE_HIST_SIZE];
        ctrace_t        rtd_unlock[CTRACE_HIST_SIZE];
        /*
         * Trash list linkage
         */
        TAILQ_ENTRY(rtentry_dbg) rtd_trash_link;
};

/* List of trash route entries protected by rnh_lock */
static TAILQ_HEAD(, rtentry_dbg) rttrash_head;

static void rte_lock_init(struct rtentry *);
static void rte_lock_destroy(struct rtentry *);
static inline struct rtentry *rte_alloc_debug(void);
static inline void rte_free_debug(struct rtentry *);
static inline void rte_lock_debug(struct rtentry_dbg *);
static inline void rte_unlock_debug(struct rtentry_dbg *);
static void rt_maskedcopy(const struct sockaddr *,
            struct sockaddr *, const struct sockaddr *);
static void rtable_init(void **);
static inline void rtref_audit(struct rtentry_dbg *);
static inline void rtunref_audit(struct rtentry_dbg *);
static struct rtentry *rtalloc1_common_locked(struct sockaddr *, int, uint32_t,
    unsigned int);
static int rtrequest_common_locked(int, struct sockaddr *,
    struct sockaddr *, struct sockaddr *, int, struct rtentry **,
    unsigned int);
static struct rtentry *rtalloc1_locked(struct sockaddr *, int, uint32_t);
static void rtalloc_ign_common_locked(struct route *, uint32_t, unsigned int);
static inline void sin6_set_ifscope(struct sockaddr *, unsigned int);
static inline void sin6_set_embedded_ifscope(struct sockaddr *, unsigned int);
static inline unsigned int sin6_get_embedded_ifscope(struct sockaddr *);
static struct sockaddr *ma_copy(int, struct sockaddr *,
    struct sockaddr_storage *, unsigned int);
static struct sockaddr *sa_trim(struct sockaddr *, int);
static struct radix_node *node_lookup(struct sockaddr *, struct sockaddr *,
    unsigned int);
static struct radix_node *node_lookup_default(int);
static struct rtentry *rt_lookup_common(boolean_t, boolean_t, struct sockaddr *,
    struct sockaddr *, struct radix_node_head *, unsigned int);
static int rn_match_ifscope(struct radix_node *, void *);
static struct ifaddr *ifa_ifwithroute_common_locked(int,
    const struct sockaddr *, const struct sockaddr *, unsigned int);
static struct rtentry *rte_alloc(void);
static void rte_free(struct rtentry *);
static void rtfree_common(struct rtentry *, boolean_t);
static void rte_if_ref(struct ifnet *, int);
static void rt_set_idleref(struct rtentry *);
static void rt_clear_idleref(struct rtentry *);
static void rt_str4(struct rtentry *, char *, uint32_t, char *, uint32_t);
#if INET6
static void rt_str6(struct rtentry *, char *, uint32_t, char *, uint32_t);
#endif /* INET6 */

uint32_t route_genid_inet = 0;
#if INET6
uint32_t route_genid_inet6 = 0;
#endif /* INET6 */

#define ASSERT_SINIFSCOPE(sa) {                                         \
        if ((sa)->sa_family != AF_INET ||                               \
            (sa)->sa_len < sizeof (struct sockaddr_in))                 \
                panic("%s: bad sockaddr_in %p\n", __func__, sa);        \
}

#define ASSERT_SIN6IFSCOPE(sa) {                                        \
        if ((sa)->sa_family != AF_INET6 ||                              \
            (sa)->sa_len < sizeof (struct sockaddr_in6))                \
                panic("%s: bad sockaddr_in6 %p\n", __func__, sa);       \
}

/*
 * Argument to leaf-matching routine; at present it is scoped routing
 * specific but can be expanded in future to include other search filters.
 */
struct matchleaf_arg {
        unsigned int    ifscope;        /* interface scope */
};

/*
 * For looking up the non-scoped default route (sockaddr instead
 * of sockaddr_in for convenience).
 */
static struct sockaddr sin_def = {
        sizeof (struct sockaddr_in), AF_INET, { 0, }
};

static struct sockaddr_in6 sin6_def = {
        sizeof (struct sockaddr_in6), AF_INET6, 0, 0, IN6ADDR_ANY_INIT, 0
};

/*
 * Interface index (scope) of the primary interface; determined at
 * the time when the default, non-scoped route gets added, changed
 * or deleted.  Protected by rnh_lock.
 */
static unsigned int primary_ifscope = IFSCOPE_NONE;
static unsigned int primary6_ifscope = IFSCOPE_NONE;

#define INET_DEFAULT(sa)        \
        ((sa)->sa_family == AF_INET && SIN(sa)->sin_addr.s_addr == 0)

#define INET6_DEFAULT(sa)                                               \
        ((sa)->sa_family == AF_INET6 &&                                 \
        IN6_IS_ADDR_UNSPECIFIED(&SIN6(sa)->sin6_addr))

#define SA_DEFAULT(sa)  (INET_DEFAULT(sa) || INET6_DEFAULT(sa))
#define RT(r)           ((struct rtentry *)r)
#define RN(r)           ((struct radix_node *)r)
#define RT_HOST(r)      (RT(r)->rt_flags & RTF_HOST)

unsigned int rt_verbose = 0;
#if (DEVELOPMENT || DEBUG)
SYSCTL_DECL(_net_route);
SYSCTL_UINT(_net_route, OID_AUTO, verbose, CTLFLAG_RW | CTLFLAG_LOCKED,
        &rt_verbose, 0, "");
#endif /* (DEVELOPMENT || DEBUG) */

static void
rtable_init(void **table)
{
        struct domain *dom;

        domain_proto_mtx_lock_assert_held();

        TAILQ_FOREACH(dom, &domains, dom_entry) {
                if (dom->dom_rtattach != NULL)
                        dom->dom_rtattach(&table[dom->dom_family],
                            dom->dom_rtoffset);
        }
}

/*
 * Called by route_dinit().
 */
void
route_init(void)
{
        int size;

#if INET6
        _CASSERT(offsetof(struct route, ro_rt) ==
            offsetof(struct route_in6, ro_rt));
        _CASSERT(offsetof(struct route, ro_srcia) ==
            offsetof(struct route_in6, ro_srcia));
        _CASSERT(offsetof(struct route, ro_flags) ==
            offsetof(struct route_in6, ro_flags));
        _CASSERT(offsetof(struct route, ro_dst) ==
            offsetof(struct route_in6, ro_dst));
#endif /* INET6 */

        PE_parse_boot_argn("rte_debug", &rte_debug, sizeof (rte_debug));
        if (rte_debug != 0)
                rte_debug |= RTD_DEBUG;

        rnh_lock_grp_attr = lck_grp_attr_alloc_init();
        rnh_lock_grp = lck_grp_alloc_init("route", rnh_lock_grp_attr);
        rnh_lock_attr = lck_attr_alloc_init();
        lck_mtx_init(rnh_lock, rnh_lock_grp, rnh_lock_attr);

        rte_mtx_grp_attr = lck_grp_attr_alloc_init();
        rte_mtx_grp = lck_grp_alloc_init(RTE_NAME, rte_mtx_grp_attr);
        rte_mtx_attr = lck_attr_alloc_init();

        lck_mtx_lock(rnh_lock);
        rn_init();      /* initialize all zeroes, all ones, mask table */
        lck_mtx_unlock(rnh_lock);
        rtable_init((void **)rt_tables);

        if (rte_debug & RTD_DEBUG)
                size = sizeof (struct rtentry_dbg);
        else
                size = sizeof (struct rtentry);

        rte_zone = zinit(size, RTE_ZONE_MAX * size, 0, RTE_ZONE_NAME);
        if (rte_zone == NULL) {
                panic("%s: failed allocating rte_zone", __func__);
                /* NOTREACHED */
        }
        zone_change(rte_zone, Z_EXPAND, TRUE);
        zone_change(rte_zone, Z_CALLERACCT, FALSE);
        zone_change(rte_zone, Z_NOENCRYPT, TRUE);

        TAILQ_INIT(&rttrash_head);
}

/*
 * Given a route, determine whether or not it is the non-scoped default
 * route; dst typically comes from rt_key(rt) but may be coming from
 * a separate place when rt is in the process of being created.
 */
boolean_t
rt_primary_default(struct rtentry *rt, struct sockaddr *dst)
{
        return (SA_DEFAULT(dst) && !(rt->rt_flags & RTF_IFSCOPE));
}

/*
 * Set the ifscope of the primary interface; caller holds rnh_lock.
 */
void
set_primary_ifscope(int af, unsigned int ifscope)
{
        if (af == AF_INET)
                primary_ifscope = ifscope;
        else
                primary6_ifscope = ifscope;
}

/*
 * Return the ifscope of the primary interface; caller holds rnh_lock.
 */
unsigned int
get_primary_ifscope(int af)
{
        return (af == AF_INET ? primary_ifscope : primary6_ifscope);
}

/*
 * Set the scope ID of a given a sockaddr_in.
 */
void
sin_set_ifscope(struct sockaddr *sa, unsigned int ifscope)
{
        /* Caller must pass in sockaddr_in */
        ASSERT_SINIFSCOPE(sa);

        SINIFSCOPE(sa)->sin_scope_id = ifscope;
}

/*
 * Set the scope ID of given a sockaddr_in6.
 */
static inline void
sin6_set_ifscope(struct sockaddr *sa, unsigned int ifscope)
{
        /* Caller must pass in sockaddr_in6 */
        ASSERT_SIN6IFSCOPE(sa);

        SIN6IFSCOPE(sa)->sin6_scope_id = ifscope;
}

/*
 * Given a sockaddr_in, return the scope ID to the caller.
 */
unsigned int
sin_get_ifscope(struct sockaddr *sa)
{
        /* Caller must pass in sockaddr_in */
        ASSERT_SINIFSCOPE(sa);

        return (SINIFSCOPE(sa)->sin_scope_id);
}

/*
 * Given a sockaddr_in6, return the scope ID to the caller.
 */
unsigned int
sin6_get_ifscope(struct sockaddr *sa)
{
        /* Caller must pass in sockaddr_in6 */
        ASSERT_SIN6IFSCOPE(sa);

        return (SIN6IFSCOPE(sa)->sin6_scope_id);
}

static inline void
sin6_set_embedded_ifscope(struct sockaddr *sa, unsigned int ifscope)
{
        /* Caller must pass in sockaddr_in6 */
        ASSERT_SIN6IFSCOPE(sa);
        VERIFY(IN6_IS_SCOPE_EMBED(&(SIN6(sa)->sin6_addr)));

        SIN6(sa)->sin6_addr.s6_addr16[1] = htons(ifscope);
}

static inline unsigned int
sin6_get_embedded_ifscope(struct sockaddr *sa)
{
        /* Caller must pass in sockaddr_in6 */
        ASSERT_SIN6IFSCOPE(sa);

        return (ntohs(SIN6(sa)->sin6_addr.s6_addr16[1]));
}

/*
 * Copy a sockaddr_{in,in6} src to a dst storage and set scope ID into dst.
 *
 * To clear the scope ID, pass is a NULL pifscope.  To set the scope ID, pass
 * in a non-NULL pifscope with non-zero ifscope.  Otherwise if pifscope is
 * non-NULL and ifscope is IFSCOPE_NONE, the existing scope ID is left intact.
 * In any case, the effective scope ID value is returned to the caller via
 * pifscope, if it is non-NULL.
 */
struct sockaddr *
sa_copy(struct sockaddr *src, struct sockaddr_storage *dst,
    unsigned int *pifscope)
{
        int af = src->sa_family;
        unsigned int ifscope = (pifscope != NULL) ? *pifscope : IFSCOPE_NONE;

        VERIFY(af == AF_INET || af == AF_INET6);

        bzero(dst, sizeof (*dst));

        if (af == AF_INET) {
                bcopy(src, dst, sizeof (struct sockaddr_in));
                if (pifscope == NULL || ifscope != IFSCOPE_NONE)
                        sin_set_ifscope(SA(dst), ifscope);
        } else {
                bcopy(src, dst, sizeof (struct sockaddr_in6));
                if (pifscope != NULL &&
                    IN6_IS_SCOPE_EMBED(&SIN6(dst)->sin6_addr)) {
                        unsigned int eifscope;
                        /*
                         * If the address contains the embedded scope ID,
                         * use that as the value for sin6_scope_id as long
                         * the caller doesn't insist on clearing it (by
                         * passing NULL) or setting it.
                         */
                        eifscope = sin6_get_embedded_ifscope(SA(dst));
                        if (eifscope != IFSCOPE_NONE && ifscope == IFSCOPE_NONE)
                                ifscope = eifscope;
                        if (ifscope != IFSCOPE_NONE) {
                                /* Set ifscope from pifscope or eifscope */
                                sin6_set_ifscope(SA(dst), ifscope);
                        } else {
                                /* If sin6_scope_id has a value, use that one */
                                ifscope = sin6_get_ifscope(SA(dst));
                        }
                        /*
                         * If sin6_scope_id is set but the address doesn't
                         * contain the equivalent embedded value, set it.
                         */
                        if (ifscope != IFSCOPE_NONE && eifscope != ifscope)
                                sin6_set_embedded_ifscope(SA(dst), ifscope);
                } else if (pifscope == NULL || ifscope != IFSCOPE_NONE) {
                        sin6_set_ifscope(SA(dst), ifscope);
                }
        }

        if (pifscope != NULL) {
                *pifscope = (af == AF_INET) ? sin_get_ifscope(SA(dst)) :
                    sin6_get_ifscope(SA(dst));
        }

        return (SA(dst));
}

/*
 * Copy a mask from src to a dst storage and set scope ID into dst.
 */
static struct sockaddr *
ma_copy(int af, struct sockaddr *src, struct sockaddr_storage *dst,
    unsigned int ifscope)
{
        VERIFY(af == AF_INET || af == AF_INET6);

        bzero(dst, sizeof (*dst));
        rt_maskedcopy(src, SA(dst), src);

        /*
         * The length of the mask sockaddr would need to be adjusted
         * to cover the additional {sin,sin6}_ifscope field; when ifscope
         * is IFSCOPE_NONE, we'd end up clearing the scope ID field on
         * the destination mask in addition to extending the length
         * of the sockaddr, as a side effect.  This is okay, as any
         * trailing zeroes would be skipped by rn_addmask prior to
         * inserting or looking up the mask in the mask tree.
         */
        if (af == AF_INET) {
                SINIFSCOPE(dst)->sin_scope_id = ifscope;
                SINIFSCOPE(dst)->sin_len =
                    offsetof(struct sockaddr_inifscope, sin_scope_id) +
                    sizeof (SINIFSCOPE(dst)->sin_scope_id);
        } else {
                SIN6IFSCOPE(dst)->sin6_scope_id = ifscope;
                SIN6IFSCOPE(dst)->sin6_len =
                    offsetof(struct sockaddr_in6, sin6_scope_id) +
                    sizeof (SIN6IFSCOPE(dst)->sin6_scope_id);
        }

        return (SA(dst));
}

/*
 * Trim trailing zeroes on a sockaddr and update its length.
 */
static struct sockaddr *
sa_trim(struct sockaddr *sa, int skip)
{
        caddr_t cp, base = (caddr_t)sa + skip;

        if (sa->sa_len <= skip)
                return (sa);

        for (cp = base + (sa->sa_len - skip); cp > base && cp[-1] == 0; )
                cp--;

        sa->sa_len = (cp - base) + skip;
        if (sa->sa_len < skip) {
                /* Must not happen, and if so, panic */
                panic("%s: broken logic (sa_len %d < skip %d )", __func__,
                    sa->sa_len, skip);
                /* NOTREACHED */
        } else if (sa->sa_len == skip) {
                /* If we end up with all zeroes, then there's no mask */
                sa->sa_len = 0;
        }

        return (sa);
}

/*
 * Called by rtm_msg{1,2} routines to "scrub" socket address structures of
 * kernel private information, so that clients of the routing socket will
 * not be confused by the presence of the information, or the side effect of
 * the increased length due to that.  The source sockaddr is not modified;
 * instead, the scrubbing happens on the destination sockaddr storage that
 * is passed in by the caller.
 *
 * Scrubbing entails:
 *   - removing embedded scope identifiers from network mask and destination
 *     IPv4 and IPv6 socket addresses
 *   - optionally removing global scope interface hardware addresses from
 *     link-layer interface addresses when the MAC framework check fails.
 */
struct sockaddr *
rtm_scrub(int type, int idx, struct sockaddr *hint, struct sockaddr *sa,
    void *buf, uint32_t buflen, kauth_cred_t *credp)
{
        struct sockaddr_storage *ss = (struct sockaddr_storage *)buf;
        struct sockaddr *ret = sa;

        VERIFY(buf != NULL && buflen >= sizeof (*ss));
        bzero(buf, buflen);

        switch (idx) {
        case RTAX_DST:
                /*
                 * If this is for an AF_INET/AF_INET6 destination address,
                 * call sa_copy() to clear the scope ID field.
                 */
                if (sa->sa_family == AF_INET &&
                    SINIFSCOPE(sa)->sin_scope_id != IFSCOPE_NONE) {
                        ret = sa_copy(sa, ss, NULL);
                } else if (sa->sa_family == AF_INET6 &&
                    SIN6IFSCOPE(sa)->sin6_scope_id != IFSCOPE_NONE) {
                        ret = sa_copy(sa, ss, NULL);
                }
                break;

        case RTAX_NETMASK: {
                int skip, af;
                /*
                 * If this is for a mask, we can't tell whether or not there
                 * is an valid scope ID value, as the span of bytes between
                 * sa_len and the beginning of the mask (offset of sin_addr in
                 * the case of AF_INET, or sin6_addr for AF_INET6) may be
                 * filled with all-ones by rn_addmask(), and hence we cannot
                 * rely on sa_family.  Because of this, we use the sa_family
                 * of the hint sockaddr (RTAX_{DST,IFA}) as indicator as to
                 * whether or not the mask is to be treated as one for AF_INET
                 * or AF_INET6.  Clearing the scope ID field involves setting
                 * it to IFSCOPE_NONE followed by calling sa_trim() to trim
                 * trailing zeroes from the storage sockaddr, which reverses
                 * what was done earlier by ma_copy() on the source sockaddr.
                 */
                if (hint == NULL ||
                    ((af = hint->sa_family) != AF_INET && af != AF_INET6))
                        break;  /* nothing to do */

                skip = (af == AF_INET) ?
                    offsetof(struct sockaddr_in, sin_addr) :
                    offsetof(struct sockaddr_in6, sin6_addr);

                if (sa->sa_len > skip && sa->sa_len <= sizeof (*ss)) {
                        bcopy(sa, ss, sa->sa_len);
                        /*
                         * Don't use {sin,sin6}_set_ifscope() as sa_family
                         * and sa_len for the netmask might not be set to
                         * the corresponding expected values of the hint.
                         */
                        if (hint->sa_family == AF_INET)
                                SINIFSCOPE(ss)->sin_scope_id = IFSCOPE_NONE;
                        else
                                SIN6IFSCOPE(ss)->sin6_scope_id = IFSCOPE_NONE;
                        ret = sa_trim(SA(ss), skip);

                        /*
                         * For AF_INET6 mask, set sa_len appropriately unless
                         * this is requested via systl_dumpentry(), in which
                         * case we return the raw value.
                         */
                        if (hint->sa_family == AF_INET6 &&
                            type != RTM_GET && type != RTM_GET2)
                                SA(ret)->sa_len = sizeof (struct sockaddr_in6);
                }
                break;
        }
        case RTAX_GATEWAY: {
                /*
                 * Break if the gateway is not AF_LINK type (indirect routes)
                 *
                 * Else, if is, check if it is resolved. If not yet resolved
                 * simply break else scrub the link layer address.
                 */
                if ((sa->sa_family != AF_LINK) || (SDL(sa)->sdl_alen == 0))
                        break;
                /* fallthrough */
        }
        case RTAX_IFP: {
                if (sa->sa_family == AF_LINK && credp) {
                        struct sockaddr_dl *sdl = SDL(buf);
                        const void *bytes;
                        size_t size;

                        /* caller should handle worst case: SOCK_MAXADDRLEN */
                        VERIFY(buflen >= sa->sa_len);

                        bcopy(sa, sdl, sa->sa_len);
                        bytes = dlil_ifaddr_bytes(sdl, &size, credp);
                        if (bytes != CONST_LLADDR(sdl)) {
                                VERIFY(sdl->sdl_alen == size);
                                bcopy(bytes, LLADDR(sdl), size);
                        }
                        ret = (struct sockaddr *)sdl;
                }
                break;
        }
        default:
                break;
        }

        return (ret);
}

/*
 * Callback leaf-matching routine for rn_matchaddr_args used
 * for looking up an exact match for a scoped route entry.
 */
static int
rn_match_ifscope(struct radix_node *rn, void *arg)
{
        struct rtentry *rt = (struct rtentry *)rn;
        struct matchleaf_arg *ma = arg;
        int af = rt_key(rt)->sa_family;

        if (!(rt->rt_flags & RTF_IFSCOPE) || (af != AF_INET && af != AF_INET6))
                return (0);

        return (af == AF_INET ?
            (SINIFSCOPE(rt_key(rt))->sin_scope_id == ma->ifscope) :
            (SIN6IFSCOPE(rt_key(rt))->sin6_scope_id == ma->ifscope));
}

/*
 * Atomically increment route generation counter
 */
void
routegenid_update(void)
{
        routegenid_inet_update();
#if INET6
        routegenid_inet6_update();
#endif /* INET6 */
}

void
routegenid_inet_update(void)
{
        atomic_add_32(&route_genid_inet, 1);
}

#if INET6
void
routegenid_inet6_update(void)
{
        atomic_add_32(&route_genid_inet6, 1);
}
#endif /* INET6 */

/*
 * Packet routing routines.
 */
void
rtalloc(struct route *ro)
{
        rtalloc_ign(ro, 0);
}

void
rtalloc_scoped(struct route *ro, unsigned int ifscope)
{
        rtalloc_scoped_ign(ro, 0, ifscope);
}

static void
rtalloc_ign_common_locked(struct route *ro, uint32_t ignore,
    unsigned int ifscope)
{
        struct rtentry *rt;

        if ((rt = ro->ro_rt) != NULL) {
                RT_LOCK_SPIN(rt);
                if (rt->rt_ifp != NULL && !ROUTE_UNUSABLE(ro)) {
                        RT_UNLOCK(rt);
                        return;
                }
                RT_UNLOCK(rt);
                ROUTE_RELEASE_LOCKED(ro);       /* rnh_lock already held */
        }
        ro->ro_rt = rtalloc1_common_locked(&ro->ro_dst, 1, ignore, ifscope);
        if (ro->ro_rt != NULL) {
                RT_GENID_SYNC(ro->ro_rt);
                RT_LOCK_ASSERT_NOTHELD(ro->ro_rt);
        }
}

void
rtalloc_ign(struct route *ro, uint32_t ignore)
{
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);
        rtalloc_ign_common_locked(ro, ignore, IFSCOPE_NONE);
        lck_mtx_unlock(rnh_lock);
}

void
rtalloc_scoped_ign(struct route *ro, uint32_t ignore, unsigned int ifscope)
{
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);
        rtalloc_ign_common_locked(ro, ignore, ifscope);
        lck_mtx_unlock(rnh_lock);
}

static struct rtentry *
rtalloc1_locked(struct sockaddr *dst, int report, uint32_t ignflags)
{
        return (rtalloc1_common_locked(dst, report, ignflags, IFSCOPE_NONE));
}

struct rtentry *
rtalloc1_scoped_locked(struct sockaddr *dst, int report, uint32_t ignflags,
    unsigned int ifscope)
{
        return (rtalloc1_common_locked(dst, report, ignflags, ifscope));
}

struct rtentry *
rtalloc1_common_locked(struct sockaddr *dst, int report, uint32_t ignflags,
    unsigned int ifscope)
{
        struct radix_node_head *rnh = rt_tables[dst->sa_family];
        struct rtentry *rt, *newrt = NULL;
        struct rt_addrinfo info;
        uint32_t nflags;
        int  err = 0, msgtype = RTM_MISS;

        if (rnh == NULL)
                goto unreachable;

        /*
         * Find the longest prefix or exact (in the scoped case) address match;
         * callee adds a reference to entry and checks for root node as well
         */
        rt = rt_lookup(FALSE, dst, NULL, rnh, ifscope);
        if (rt == NULL)
                goto unreachable;

        RT_LOCK_SPIN(rt);
        newrt = rt;
        nflags = rt->rt_flags & ~ignflags;
        RT_UNLOCK(rt);
        if (report && (nflags & (RTF_CLONING | RTF_PRCLONING))) {
                /*
                 * We are apparently adding (report = 0 in delete).
                 * If it requires that it be cloned, do so.
                 * (This implies it wasn't a HOST route.)
                 */
                err = rtrequest_locked(RTM_RESOLVE, dst, NULL, NULL, 0, &newrt);
                if (err) {
                        /*
                         * If the cloning didn't succeed, maybe what we
                         * have from lookup above will do.  Return that;
                         * no need to hold another reference since it's
                         * already done.
                         */
                        newrt = rt;
                        goto miss;
                }

                /*
                 * We cloned it; drop the original route found during lookup.
                 * The resulted cloned route (newrt) would now have an extra
                 * reference held during rtrequest.
                 */
                rtfree_locked(rt);

                /*
                 * If the newly created cloned route is a direct host route
                 * then also check if it is to a router or not.
                 * If it is, then set the RTF_ROUTER flag on the host route
                 * for the gateway.
                 *
                 * XXX It is possible for the default route to be created post
                 * cloned route creation of router's IP.
                 * We can handle that corner case by special handing for RTM_ADD
                 * of default route.
                 */
                if ((newrt->rt_flags & (RTF_HOST | RTF_LLINFO)) ==
                    (RTF_HOST | RTF_LLINFO)) {
                        struct rtentry *defrt = NULL;
                        struct sockaddr_storage def_key;

                        bzero(&def_key, sizeof(def_key));
                        def_key.ss_len = rt_key(newrt)->sa_len;
                        def_key.ss_family = rt_key(newrt)->sa_family;

                        defrt = rtalloc1_scoped_locked((struct sockaddr *)&def_key,
                                        0, 0, newrt->rt_ifp->if_index);

                        if (defrt) {
                                if (equal(rt_key(newrt), defrt->rt_gateway)) {
                                        newrt->rt_flags |= RTF_ROUTER;
                                }
                                rtfree_locked(defrt);
                        }
                }

                if ((rt = newrt) && (rt->rt_flags & RTF_XRESOLVE)) {
                        /*
                         * If the new route specifies it be
                         * externally resolved, then go do that.
                         */
                        msgtype = RTM_RESOLVE;
                        goto miss;
                }
        }
        goto done;

unreachable:
        /*
         * Either we hit the root or couldn't find any match,
         * Which basically means "cant get there from here"
         */
        rtstat.rts_unreach++;

miss:
        if (report) {
                /*
                 * If required, report the failure to the supervising
                 * Authorities.
                 * For a delete, this is not an error. (report == 0)
                 */
                bzero((caddr_t)&info, sizeof(info));
                info.rti_info[RTAX_DST] = dst;
                rt_missmsg(msgtype, &info, 0, err);
        }
done:
        return (newrt);
}

struct rtentry *
rtalloc1(struct sockaddr *dst, int report, uint32_t ignflags)
{
        struct rtentry *entry;
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);
        entry = rtalloc1_locked(dst, report, ignflags);
        lck_mtx_unlock(rnh_lock);
        return (entry);
}

struct rtentry *
rtalloc1_scoped(struct sockaddr *dst, int report, uint32_t ignflags,
    unsigned int ifscope)
{
        struct rtentry *entry;
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);
        entry = rtalloc1_scoped_locked(dst, report, ignflags, ifscope);
        lck_mtx_unlock(rnh_lock);
        return (entry);
}

/*
 * Remove a reference count from an rtentry.
 * If the count gets low enough, take it out of the routing table
 */
void
rtfree_locked(struct rtentry *rt)
{
        rtfree_common(rt, TRUE);
}

static void
rtfree_common(struct rtentry *rt, boolean_t locked)
{
        struct radix_node_head *rnh;

        lck_mtx_assert(rnh_lock, locked ?
            LCK_MTX_ASSERT_OWNED : LCK_MTX_ASSERT_NOTOWNED);

        /*
         * Atomically decrement the reference count and if it reaches 0,
         * and there is a close function defined, call the close function.
         */
        RT_LOCK_SPIN(rt);
        if (rtunref(rt) > 0) {
                RT_UNLOCK(rt);
                return;
        }

        /*
         * To avoid violating lock ordering, we must drop rt_lock before
         * trying to acquire the global rnh_lock.  If we are called with
         * rnh_lock held, then we already have exclusive access; otherwise
         * we do the lock dance.
         */
        if (!locked) {
                /*
                 * Note that we check it again below after grabbing rnh_lock,
                 * since it is possible that another thread doing a lookup wins
                 * the race, grabs the rnh_lock first, and bumps up reference
                 * count in which case the route should be left alone as it is
                 * still in use.  It's also possible that another thread frees
                 * the route after we drop rt_lock; to prevent the route from
                 * being freed, we hold an extra reference.
                 */
                RT_ADDREF_LOCKED(rt);
                RT_UNLOCK(rt);
                lck_mtx_lock(rnh_lock);
                RT_LOCK_SPIN(rt);
                if (rtunref(rt) > 0) {
                        /* We've lost the race, so abort */
                        RT_UNLOCK(rt);
                        goto done;
                }
        }

        /*
         * We may be blocked on other lock(s) as part of freeing
         * the entry below, so convert from spin to full mutex.
         */
        RT_CONVERT_LOCK(rt);

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        /* Negative refcnt must never happen */
        if (rt->rt_refcnt != 0) {
                panic("rt %p invalid refcnt %d", rt, rt->rt_refcnt);
                /* NOTREACHED */
        }
        /* Idle refcnt must have been dropped during rtunref() */
        VERIFY(!(rt->rt_flags & RTF_IFREF));

        /*
         * find the tree for that address family
         * Note: in the case of igmp packets, there might not be an rnh
         */
        rnh = rt_tables[rt_key(rt)->sa_family];

        /*
         * On last reference give the "close method" a chance to cleanup
         * private state.  This also permits (for IPv4 and IPv6) a chance
         * to decide if the routing table entry should be purged immediately
         * or at a later time.  When an immediate purge is to happen the
         * close routine typically issues RTM_DELETE which clears the RTF_UP
         * flag on the entry so that the code below reclaims the storage.
         */
        if (rnh != NULL && rnh->rnh_close != NULL)
                rnh->rnh_close((struct radix_node *)rt, rnh);

        /*
         * If we are no longer "up" (and ref == 0) then we can free the
         * resources associated with the route.
         */
        if (!(rt->rt_flags & RTF_UP)) {
                struct rtentry *rt_parent;
                struct ifaddr *rt_ifa;

                if (rt->rt_nodes->rn_flags & (RNF_ACTIVE | RNF_ROOT)) {
                        panic("rt %p freed while in radix tree\n", rt);
                        /* NOTREACHED */
                }
                /*
                 * the rtentry must have been removed from the routing table
                 * so it is represented in rttrash; remove that now.
                 */
                (void) OSDecrementAtomic(&rttrash);
                if (rte_debug & RTD_DEBUG) {
                        TAILQ_REMOVE(&rttrash_head, (struct rtentry_dbg *)rt,
                            rtd_trash_link);
                }

                /*
                 * release references on items we hold them on..
                 * e.g other routes and ifaddrs.
                 */
                if ((rt_parent = rt->rt_parent) != NULL)
                        rt->rt_parent = NULL;

                if ((rt_ifa = rt->rt_ifa) != NULL)
                        rt->rt_ifa = NULL;

                /*
                 * Now free any attached link-layer info.
                 */
                if (rt->rt_llinfo != NULL) {
                        if (rt->rt_llinfo_free != NULL)
                                (*rt->rt_llinfo_free)(rt->rt_llinfo);
                        else
                                R_Free(rt->rt_llinfo);
                        rt->rt_llinfo = NULL;
                }

                /*
                 * Route is no longer in the tree and refcnt is 0;
                 * we have exclusive access, so destroy it.
                 */
                RT_UNLOCK(rt);

                if (rt_parent != NULL)
                        rtfree_locked(rt_parent);

                if (rt_ifa != NULL)
                        IFA_REMREF(rt_ifa);

                /*
                 * The key is separately alloc'd so free it (see rt_setgate()).
                 * This also frees the gateway, as they are always malloc'd
                 * together.
                 */
                R_Free(rt_key(rt));

                /*
                 * Free any statistics that may have been allocated
                 */
                nstat_route_detach(rt);

                /*
                 * and the rtentry itself of course
                 */
                rte_lock_destroy(rt);
                rte_free(rt);
        } else {
                /*
                 * The "close method" has been called, but the route is
                 * still in the radix tree with zero refcnt, i.e. "up"
                 * and in the cached state.
                 */
                RT_UNLOCK(rt);
        }
done:
        if (!locked)
                lck_mtx_unlock(rnh_lock);
}

void
rtfree(struct rtentry *rt)
{
        rtfree_common(rt, FALSE);
}

/*
 * Decrements the refcount but does not free the route when
 * the refcount reaches zero. Unless you have really good reason,
 * use rtfree not rtunref.
 */
int
rtunref(struct rtentry *p)
{
        RT_LOCK_ASSERT_HELD(p);

        if (p->rt_refcnt == 0) {
                panic("%s(%p) bad refcnt\n", __func__, p);
                /* NOTREACHED */
        } else if (--p->rt_refcnt == 0) {
                /*
                 * Release any idle reference count held on the interface;
                 * if the route is eligible, still UP and the refcnt becomes
                 * non-zero at some point in future before it is purged from
                 * the routing table, rt_set_idleref() will undo this.
                 */
                rt_clear_idleref(p);
        }

        if (rte_debug & RTD_DEBUG)
                rtunref_audit((struct rtentry_dbg *)p);

        /* Return new value */
        return (p->rt_refcnt);
}

static inline void
rtunref_audit(struct rtentry_dbg *rte)
{
        uint16_t idx;

        if (rte->rtd_inuse != RTD_INUSE) {
                panic("rtunref: on freed rte=%p\n", rte);
                /* NOTREACHED */
        }
        idx = atomic_add_16_ov(&rte->rtd_refrele_cnt, 1) % CTRACE_HIST_SIZE;
        if (rte_debug & RTD_TRACE)
                ctrace_record(&rte->rtd_refrele[idx]);
}

/*
 * Add a reference count from an rtentry.
 */
void
rtref(struct rtentry *p)
{
        RT_LOCK_ASSERT_HELD(p);

        if (++p->rt_refcnt == 0) {
                panic("%s(%p) bad refcnt\n", __func__, p);
                /* NOTREACHED */
        } else if (p->rt_refcnt == 1) {
                /*
                 * Hold an idle reference count on the interface,
                 * if the route is eligible for it.
                 */
                rt_set_idleref(p);
        }

        if (rte_debug & RTD_DEBUG)
                rtref_audit((struct rtentry_dbg *)p);
}

static inline void
rtref_audit(struct rtentry_dbg *rte)
{
        uint16_t idx;

        if (rte->rtd_inuse != RTD_INUSE) {
                panic("rtref_audit: on freed rte=%p\n", rte);
                /* NOTREACHED */
        }
        idx = atomic_add_16_ov(&rte->rtd_refhold_cnt, 1) % CTRACE_HIST_SIZE;
        if (rte_debug & RTD_TRACE)
                ctrace_record(&rte->rtd_refhold[idx]);
}

void
rtsetifa(struct rtentry *rt, struct ifaddr *ifa)
{
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        RT_LOCK_ASSERT_HELD(rt);

        if (rt->rt_ifa == ifa)
                return;

        /* Become a regular mutex, just in case */
        RT_CONVERT_LOCK(rt);

        /* Release the old ifa */
        if (rt->rt_ifa)
                IFA_REMREF(rt->rt_ifa);

        /* Set rt_ifa */
        rt->rt_ifa = ifa;

        /* Take a reference to the ifa */
        if (rt->rt_ifa)
                IFA_ADDREF(rt->rt_ifa);
}

/*
 * Force a routing table entry to the specified
 * destination to go through the given gateway.
 * Normally called as a result of a routing redirect
 * message from the network layer.
 */
void
rtredirect(struct ifnet *ifp, struct sockaddr *dst, struct sockaddr *gateway,
    struct sockaddr *netmask, int flags, struct sockaddr *src,
    struct rtentry **rtp)
{
        struct rtentry *rt = NULL;
        int error = 0;
        short *stat = 0;
        struct rt_addrinfo info;
        struct ifaddr *ifa = NULL;
        unsigned int ifscope = (ifp != NULL) ? ifp->if_index : IFSCOPE_NONE;
        struct sockaddr_storage ss;
        int af = src->sa_family;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);

        /*
         * Transform src into the internal routing table form for
         * comparison against rt_gateway below.
         */
#if INET6
        if ((af == AF_INET) || (af == AF_INET6))
#else
        if (af == AF_INET)
#endif /* !INET6 */
                src = sa_copy(src, &ss, &ifscope);

        /*
         * Verify the gateway is directly reachable; if scoped routing
         * is enabled, verify that it is reachable from the interface
         * where the ICMP redirect arrived on.
         */
        if ((ifa = ifa_ifwithnet_scoped(gateway, ifscope)) == NULL) {
                error = ENETUNREACH;
                goto out;
        }

        /* Lookup route to the destination (from the original IP header) */
        rt = rtalloc1_scoped_locked(dst, 0, RTF_CLONING|RTF_PRCLONING, ifscope);
        if (rt != NULL)
                RT_LOCK(rt);

        /*
         * If the redirect isn't from our current router for this dst,
         * it's either old or wrong.  If it redirects us to ourselves,
         * we have a routing loop, perhaps as a result of an interface
         * going down recently.  Holding rnh_lock here prevents the
         * possibility of rt_ifa/ifa's ifa_addr from changing (e.g.
         * in_ifinit), so okay to access ifa_addr without locking.
         */
        if (!(flags & RTF_DONE) && rt != NULL &&
            (!equal(src, rt->rt_gateway) || !equal(rt->rt_ifa->ifa_addr,
            ifa->ifa_addr))) {
                error = EINVAL;
        } else {
                IFA_REMREF(ifa);
                if ((ifa = ifa_ifwithaddr(gateway))) {
                        IFA_REMREF(ifa);
                        ifa = NULL;
                        error = EHOSTUNREACH;
                }
        }

        if (ifa) {
                IFA_REMREF(ifa);
                ifa = NULL;
        }

        if (error) {
                if (rt != NULL)
                        RT_UNLOCK(rt);
                goto done;
        }

        /*
         * Create a new entry if we just got back a wildcard entry
         * or the the lookup failed.  This is necessary for hosts
         * which use routing redirects generated by smart gateways
         * to dynamically build the routing tables.
         */
        if ((rt == NULL) || (rt_mask(rt) != NULL && rt_mask(rt)->sa_len < 2))
                goto create;
        /*
         * Don't listen to the redirect if it's
         * for a route to an interface.
         */
        RT_LOCK_ASSERT_HELD(rt);
        if (rt->rt_flags & RTF_GATEWAY) {
                if (((rt->rt_flags & RTF_HOST) == 0) && (flags & RTF_HOST)) {
                        /*
                         * Changing from route to net => route to host.
                         * Create new route, rather than smashing route
                         * to net; similar to cloned routes, the newly
                         * created host route is scoped as well.
                         */
create:
                        if (rt != NULL)
                                RT_UNLOCK(rt);
                        flags |=  RTF_GATEWAY | RTF_DYNAMIC;
                        error = rtrequest_scoped_locked(RTM_ADD, dst,
                            gateway, netmask, flags, NULL, ifscope);
                        stat = &rtstat.rts_dynamic;
                } else {
                        /*
                         * Smash the current notion of the gateway to
                         * this destination.  Should check about netmask!!!
                         */
                        rt->rt_flags |= RTF_MODIFIED;
                        flags |= RTF_MODIFIED;
                        stat = &rtstat.rts_newgateway;
                        /*
                         * add the key and gateway (in one malloc'd chunk).
                         */
                        error = rt_setgate(rt, rt_key(rt), gateway);
                        RT_UNLOCK(rt);
                }
        } else {
                RT_UNLOCK(rt);
                error = EHOSTUNREACH;
        }
done:
        if (rt != NULL) {
                RT_LOCK_ASSERT_NOTHELD(rt);
                if (rtp && !error)
                        *rtp = rt;
                else
                        rtfree_locked(rt);
        }
out:
        if (error) {
                rtstat.rts_badredirect++;
        } else {
                if (stat != NULL)
                        (*stat)++;

                if (af == AF_INET)
                        routegenid_inet_update();
#if INET6
                else if (af == AF_INET6)
                        routegenid_inet6_update();
#endif /* INET6 */
        }
        lck_mtx_unlock(rnh_lock);
        bzero((caddr_t)&info, sizeof(info));
        info.rti_info[RTAX_DST] = dst;
        info.rti_info[RTAX_GATEWAY] = gateway;
        info.rti_info[RTAX_NETMASK] = netmask;
        info.rti_info[RTAX_AUTHOR] = src;
        rt_missmsg(RTM_REDIRECT, &info, flags, error);
}

/*
* Routing table ioctl interface.
*/
int
rtioctl(unsigned long req, caddr_t data, struct proc *p)
{
#pragma unused(p, req, data)
        return (ENXIO);
}

struct ifaddr *
ifa_ifwithroute(
        int flags,
        const struct sockaddr   *dst,
        const struct sockaddr *gateway)
{
        struct ifaddr *ifa;

        lck_mtx_lock(rnh_lock);
        ifa = ifa_ifwithroute_locked(flags, dst, gateway);
        lck_mtx_unlock(rnh_lock);

        return (ifa);
}

struct ifaddr *
ifa_ifwithroute_locked(int flags, const struct sockaddr *dst,
    const struct sockaddr *gateway)
{
        return (ifa_ifwithroute_common_locked((flags & ~RTF_IFSCOPE), dst,
            gateway, IFSCOPE_NONE));
}

struct ifaddr *
ifa_ifwithroute_scoped_locked(int flags, const struct sockaddr *dst,
    const struct sockaddr *gateway, unsigned int ifscope)
{
        if (ifscope != IFSCOPE_NONE)
                flags |= RTF_IFSCOPE;
        else
                flags &= ~RTF_IFSCOPE;

        return (ifa_ifwithroute_common_locked(flags, dst, gateway, ifscope));
}

static struct ifaddr *
ifa_ifwithroute_common_locked(int flags, const struct sockaddr *dst,
    const struct sockaddr *gw, unsigned int ifscope)
{
        struct ifaddr *ifa = NULL;
        struct rtentry *rt = NULL;
        struct sockaddr_storage dst_ss, gw_ss;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        /*
         * Just in case the sockaddr passed in by the caller
         * contains a scope ID, make sure to clear it since
         * interface addresses aren't scoped.
         */
#if INET6
        if (dst != NULL &&
            ((dst->sa_family == AF_INET) ||
            (dst->sa_family == AF_INET6)))
#else
        if (dst != NULL && dst->sa_family == AF_INET)
#endif /* !INET6 */
                dst = sa_copy(SA((uintptr_t)dst), &dst_ss, NULL);

#if INET6
        if (gw != NULL &&
            ((gw->sa_family == AF_INET) ||
            (gw->sa_family == AF_INET6)))
#else
        if (gw != NULL && gw->sa_family == AF_INET)
#endif /* !INET6 */
                gw = sa_copy(SA((uintptr_t)gw), &gw_ss, NULL);

        if (!(flags & RTF_GATEWAY)) {
                /*
                 * If we are adding a route to an interface,
                 * and the interface is a pt to pt link
                 * we should search for the destination
                 * as our clue to the interface.  Otherwise
                 * we can use the local address.
                 */
                if (flags & RTF_HOST) {
                        ifa = ifa_ifwithdstaddr(dst);
                }
                if (ifa == NULL)
                        ifa = ifa_ifwithaddr_scoped(gw, ifscope);
        } else {
                /*
                 * If we are adding a route to a remote net
                 * or host, the gateway may still be on the
                 * other end of a pt to pt link.
                 */
                ifa = ifa_ifwithdstaddr(gw);
        }
        if (ifa == NULL)
                ifa = ifa_ifwithnet_scoped(gw, ifscope);
        if (ifa == NULL) {
                /* Workaround to avoid gcc warning regarding const variable */
                rt = rtalloc1_scoped_locked((struct sockaddr *)(size_t)dst,
                    0, 0, ifscope);
                if (rt != NULL) {
                        RT_LOCK_SPIN(rt);
                        ifa = rt->rt_ifa;
                        if (ifa != NULL) {
                                /* Become a regular mutex */
                                RT_CONVERT_LOCK(rt);
                                IFA_ADDREF(ifa);
                        }
                        RT_REMREF_LOCKED(rt);
                        RT_UNLOCK(rt);
                        rt = NULL;
                }
        }
        /*
         * Holding rnh_lock here prevents the possibility of ifa from
         * changing (e.g. in_ifinit), so it is safe to access its
         * ifa_addr (here and down below) without locking.
         */
        if (ifa != NULL && ifa->ifa_addr->sa_family != dst->sa_family) {
                struct ifaddr *newifa;
                /* Callee adds reference to newifa upon success */
                newifa = ifaof_ifpforaddr(dst, ifa->ifa_ifp);
                if (newifa != NULL) {
                        IFA_REMREF(ifa);
                        ifa = newifa;
                }
        }
        /*
         * If we are adding a gateway, it is quite possible that the
         * routing table has a static entry in place for the gateway,
         * that may not agree with info garnered from the interfaces.
         * The routing table should carry more precedence than the
         * interfaces in this matter.  Must be careful not to stomp
         * on new entries from rtinit, hence (ifa->ifa_addr != gw).
         */
        if ((ifa == NULL ||
            !equal(ifa->ifa_addr, (struct sockaddr *)(size_t)gw)) &&
            (rt = rtalloc1_scoped_locked((struct sockaddr *)(size_t)gw,
            0, 0, ifscope)) != NULL) {
                if (ifa != NULL)
                        IFA_REMREF(ifa);
                RT_LOCK_SPIN(rt);
                ifa = rt->rt_ifa;
                if (ifa != NULL) {
                        /* Become a regular mutex */
                        RT_CONVERT_LOCK(rt);
                        IFA_ADDREF(ifa);
                }
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
        }
        /*
         * If an interface scope was specified, the interface index of
         * the found ifaddr must be equivalent to that of the scope;
         * otherwise there is no match.
         */
        if ((flags & RTF_IFSCOPE) &&
            ifa != NULL && ifa->ifa_ifp->if_index != ifscope) {
                IFA_REMREF(ifa);
                ifa = NULL;
        }

        return (ifa);
}

static int rt_fixdelete(struct radix_node *, void *);
static int rt_fixchange(struct radix_node *, void *);

struct rtfc_arg {
        struct rtentry *rt0;
        struct radix_node_head *rnh;
};

int
rtrequest_locked(int req, struct sockaddr *dst, struct sockaddr *gateway,
    struct sockaddr *netmask, int flags, struct rtentry **ret_nrt)
{
        return (rtrequest_common_locked(req, dst, gateway, netmask,
            (flags & ~RTF_IFSCOPE), ret_nrt, IFSCOPE_NONE));
}

int
rtrequest_scoped_locked(int req, struct sockaddr *dst,
    struct sockaddr *gateway, struct sockaddr *netmask, int flags,
    struct rtentry **ret_nrt, unsigned int ifscope)
{
        if (ifscope != IFSCOPE_NONE)
                flags |= RTF_IFSCOPE;
        else
                flags &= ~RTF_IFSCOPE;

        return (rtrequest_common_locked(req, dst, gateway, netmask,
            flags, ret_nrt, ifscope));
}

/*
 * Do appropriate manipulations of a routing tree given all the bits of
 * info needed.
 *
 * Storing the scope ID in the radix key is an internal job that should be
 * left to routines in this module.  Callers should specify the scope value
 * to the "scoped" variants of route routines instead of manipulating the
 * key itself.  This is typically done when creating a scoped route, e.g.
 * rtrequest(RTM_ADD).  Once such a route is created and marked with the
 * RTF_IFSCOPE flag, callers can simply use its rt_key(rt) to clone it
 * (RTM_RESOLVE) or to remove it (RTM_DELETE).  An exception to this is
 * during certain routing socket operations where the search key might be
 * derived from the routing message itself, in which case the caller must
 * specify the destination address and scope value for RTM_ADD/RTM_DELETE.
 */
static int
rtrequest_common_locked(int req, struct sockaddr *dst0,
    struct sockaddr *gateway, struct sockaddr *netmask, int flags,
    struct rtentry **ret_nrt, unsigned int ifscope)
{
        int error = 0;
        struct rtentry *rt;
        struct radix_node *rn;
        struct radix_node_head *rnh;
        struct ifaddr *ifa = NULL;
        struct sockaddr *ndst, *dst = dst0;
        struct sockaddr_storage ss, mask;
        struct timeval caltime;
        int af = dst->sa_family;
        void (*ifa_rtrequest)(int, struct rtentry *, struct sockaddr *);

#define senderr(x) { error = x; goto bad; }

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
        /*
         * Find the correct routing tree to use for this Address Family
         */
        if ((rnh = rt_tables[af]) == NULL)
                senderr(ESRCH);
        /*
         * If we are adding a host route then we don't want to put
         * a netmask in the tree
         */
        if (flags & RTF_HOST)
                netmask = NULL;

        /*
         * If Scoped Routing is enabled, use a local copy of the destination
         * address to store the scope ID into.  This logic is repeated below
         * in the RTM_RESOLVE handler since the caller does not normally
         * specify such a flag during a resolve, as well as for the handling
         * of IPv4 link-local address; instead, it passes in the route used for
         * cloning for which the scope info is derived from.  Note also that
         * in the case of RTM_DELETE, the address passed in by the caller
         * might already contain the scope ID info when it is the key itself,
         * thus making RTF_IFSCOPE unnecessary; one instance where it is
         * explicitly set is inside route_output() as part of handling a
         * routing socket request.
         */
#if INET6
        if (req != RTM_RESOLVE && ((af == AF_INET) || (af == AF_INET6))) {
#else
        if (req != RTM_RESOLVE && af == AF_INET) {
#endif /* !INET6 */
                /* Transform dst into the internal routing table form */
                dst = sa_copy(dst, &ss, &ifscope);

                /* Transform netmask into the internal routing table form */
                if (netmask != NULL)
                        netmask = ma_copy(af, netmask, &mask, ifscope);

                if (ifscope != IFSCOPE_NONE)
                        flags |= RTF_IFSCOPE;
        } else if ((flags & RTF_IFSCOPE) &&
            (af != AF_INET && af != AF_INET6)) {
                senderr(EINVAL);
        }

        if (ifscope == IFSCOPE_NONE)
                flags &= ~RTF_IFSCOPE;

        switch (req) {
        case RTM_DELETE: {
                struct rtentry *gwrt = NULL;
                /*
                 * Remove the item from the tree and return it.
                 * Complain if it is not there and do no more processing.
                 */
                if ((rn = rnh->rnh_deladdr(dst, netmask, rnh)) == NULL)
                        senderr(ESRCH);
                if (rn->rn_flags & (RNF_ACTIVE | RNF_ROOT)) {
                        panic("rtrequest delete");
                        /* NOTREACHED */
                }
                rt = (struct rtentry *)rn;

                RT_LOCK(rt);
                rt->rt_flags &= ~RTF_UP;
                /*
                 * Release any idle reference count held on the interface
                 * as this route is no longer externally visible.
                 */
                rt_clear_idleref(rt);
                /*
                 * Take an extra reference to handle the deletion of a route
                 * entry whose reference count is already 0; e.g. an expiring
                 * cloned route entry or an entry that was added to the table
                 * with 0 reference. If the caller is interested in this route,
                 * we will return it with the reference intact. Otherwise we
                 * will decrement the reference via rtfree_locked() and then
                 * possibly deallocate it.
                 */
                RT_ADDREF_LOCKED(rt);

                /*
                 * For consistency, in case the caller didn't set the flag.
                 */
                rt->rt_flags |= RTF_CONDEMNED;

                /*
                 * Clear RTF_ROUTER if it's set.
                 */
                if (rt->rt_flags & RTF_ROUTER) {
                        VERIFY(rt->rt_flags & RTF_HOST);
                        rt->rt_flags &= ~RTF_ROUTER;
                }

                /*
                 * Now search what's left of the subtree for any cloned
                 * routes which might have been formed from this node.
                 */
                if ((rt->rt_flags & (RTF_CLONING | RTF_PRCLONING)) &&
                    rt_mask(rt)) {
                        RT_UNLOCK(rt);
                        rnh->rnh_walktree_from(rnh, dst, rt_mask(rt),
                            rt_fixdelete, rt);
                        RT_LOCK(rt);
                }

                /*
                 * Remove any external references we may have.
                 */
                if ((gwrt = rt->rt_gwroute) != NULL)
                        rt->rt_gwroute = NULL;

                /*
                 * give the protocol a chance to keep things in sync.
                 */
                if ((ifa = rt->rt_ifa) != NULL) {
                        IFA_LOCK_SPIN(ifa);
                        ifa_rtrequest = ifa->ifa_rtrequest;
                        IFA_UNLOCK(ifa);
                        if (ifa_rtrequest != NULL)
                                ifa_rtrequest(RTM_DELETE, rt, NULL);
                        /* keep reference on rt_ifa */
                        ifa = NULL;
                }

                /*
                 * one more rtentry floating around that is not
                 * linked to the routing table.
                 */
                (void) OSIncrementAtomic(&rttrash);
                if (rte_debug & RTD_DEBUG) {
                        TAILQ_INSERT_TAIL(&rttrash_head,
                            (struct rtentry_dbg *)rt, rtd_trash_link);
                }

                /*
                 * If this is the (non-scoped) default route, clear
                 * the interface index used for the primary ifscope.
                 */
                if (rt_primary_default(rt, rt_key(rt))) {
                        set_primary_ifscope(rt_key(rt)->sa_family,
                            IFSCOPE_NONE);
                }

                RT_UNLOCK(rt);

                /*
                 * This might result in another rtentry being freed if
                 * we held its last reference.  Do this after the rtentry
                 * lock is dropped above, as it could lead to the same
                 * lock being acquired if gwrt is a clone of rt.
                 */
                if (gwrt != NULL)
                        rtfree_locked(gwrt);

                /*
                 * If the caller wants it, then it can have it,
                 * but it's up to it to free the rtentry as we won't be
                 * doing it.
                 */
                if (ret_nrt != NULL) {
                        /* Return the route to caller with reference intact */
                        *ret_nrt = rt;
                } else {
                        /* Dereference or deallocate the route */
                        rtfree_locked(rt);
                }
                if (af == AF_INET)
                        routegenid_inet_update();
#if INET6
                else if (af == AF_INET6)
                        routegenid_inet6_update();
#endif /* INET6 */
                break;
        }
        case RTM_RESOLVE:
                if (ret_nrt == NULL || (rt = *ret_nrt) == NULL)
                        senderr(EINVAL);
                /*
                 * According to the UNIX conformance tests, we need to return
                 * ENETUNREACH when the parent route is RTF_REJECT.
                 * However, there isn't any point in cloning RTF_REJECT
                 * routes, so we immediately return an error.
                 */
                if (rt->rt_flags & RTF_REJECT) {
                        if (rt->rt_flags & RTF_HOST) {
                                senderr(EHOSTUNREACH);
                        } else {
                                senderr(ENETUNREACH);
                        }
                }
                /*
                 * If cloning, we have the parent route given by the caller
                 * and will use its rt_gateway, rt_rmx as part of the cloning
                 * process below.  Since rnh_lock is held at this point, the
                 * parent's rt_ifa and rt_gateway will not change, and its
                 * relevant rt_flags will not change as well.  The only thing
                 * that could change are the metrics, and thus we hold the
                 * parent route's rt_lock later on during the actual copying
                 * of rt_rmx.
                 */
                ifa = rt->rt_ifa;
                IFA_ADDREF(ifa);
                flags = rt->rt_flags &
                    ~(RTF_CLONING | RTF_PRCLONING | RTF_STATIC);
                flags |= RTF_WASCLONED;
                gateway = rt->rt_gateway;
                if ((netmask = rt->rt_genmask) == NULL)
                        flags |= RTF_HOST;

#if INET6
                if (af != AF_INET && af != AF_INET6)
#else
                if (af != AF_INET)
#endif /* !INET6 */
                        goto makeroute;

                /*
                 * When scoped routing is enabled, cloned entries are
                 * always scoped according to the interface portion of
                 * the parent route.  The exception to this are IPv4
                 * link local addresses, or those routes that are cloned
                 * from a RTF_PROXY route.  For the latter, the clone
                 * gets to keep the RTF_PROXY flag.
                 */
                if ((af == AF_INET &&
                    IN_LINKLOCAL(ntohl(SIN(dst)->sin_addr.s_addr))) ||
                    (rt->rt_flags & RTF_PROXY)) {
                        ifscope = IFSCOPE_NONE;
                        flags &= ~RTF_IFSCOPE;
                        /*
                         * These types of cloned routes aren't currently
                         * eligible for idle interface reference counting.
                         */
                        flags |= RTF_NOIFREF;
                } else {
                        if (flags & RTF_IFSCOPE) {
                                ifscope = (af == AF_INET) ?
                                    sin_get_ifscope(rt_key(rt)) :
                                    sin6_get_ifscope(rt_key(rt));
                        } else {
                                ifscope = rt->rt_ifp->if_index;
                                flags |= RTF_IFSCOPE;
                        }
                        VERIFY(ifscope != IFSCOPE_NONE);
                }

                /*
                 * Transform dst into the internal routing table form,
                 * clearing out the scope ID field if ifscope isn't set.
                 */
                dst = sa_copy(dst, &ss, (ifscope == IFSCOPE_NONE) ?
                    NULL : &ifscope);

                /* Transform netmask into the internal routing table form */
                if (netmask != NULL)
                        netmask = ma_copy(af, netmask, &mask, ifscope);

                goto makeroute;

        case RTM_ADD:
                if ((flags & RTF_GATEWAY) && !gateway) {
                        panic("rtrequest: RTF_GATEWAY but no gateway");
                        /* NOTREACHED */
                }
                if (flags & RTF_IFSCOPE) {
                        ifa = ifa_ifwithroute_scoped_locked(flags, dst0,
                            gateway, ifscope);
                } else {
                        ifa = ifa_ifwithroute_locked(flags, dst0, gateway);
                }
                if (ifa == NULL)
                        senderr(ENETUNREACH);
makeroute:
                if ((rt = rte_alloc()) == NULL)
                        senderr(ENOBUFS);
                Bzero(rt, sizeof(*rt));
                rte_lock_init(rt);
                getmicrotime(&caltime);
                rt->base_calendartime = caltime.tv_sec;
                rt->base_uptime = net_uptime();
                RT_LOCK(rt);
                rt->rt_flags = RTF_UP | flags;

                /*
                 * Point the generation ID to the tree's.
                 */
                switch (af) {
                case AF_INET:
                        rt->rt_tree_genid = &route_genid_inet;
                        break;
#if INET6
                case AF_INET6:
                        rt->rt_tree_genid = &route_genid_inet6;
                        break;
#endif /* INET6 */
                default:
                        break;
                }

                /*
                 * Add the gateway. Possibly re-malloc-ing the storage for it
                 * also add the rt_gwroute if possible.
                 */
                if ((error = rt_setgate(rt, dst, gateway)) != 0) {
                        int tmp = error;
                        RT_UNLOCK(rt);
                        nstat_route_detach(rt);
                        rte_lock_destroy(rt);
                        rte_free(rt);
                        senderr(tmp);
                }

                /*
                 * point to the (possibly newly malloc'd) dest address.
                 */
                ndst = rt_key(rt);

                /*
                 * make sure it contains the value we want (masked if needed).
                 */
                if (netmask)
                        rt_maskedcopy(dst, ndst, netmask);
                else
                        Bcopy(dst, ndst, dst->sa_len);

                /*
                 * Note that we now have a reference to the ifa.
                 * This moved from below so that rnh->rnh_addaddr() can
                 * examine the ifa and  ifa->ifa_ifp if it so desires.
                 */
                rtsetifa(rt, ifa);
                rt->rt_ifp = rt->rt_ifa->ifa_ifp;

                /* XXX mtu manipulation will be done in rnh_addaddr -- itojun */

                rn = rnh->rnh_addaddr((caddr_t)ndst, (caddr_t)netmask,
                    rnh, rt->rt_nodes);
                if (rn == 0) {
                        struct rtentry *rt2;
                        /*
                         * Uh-oh, we already have one of these in the tree.
                         * We do a special hack: if the route that's already
                         * there was generated by the protocol-cloning
                         * mechanism, then we just blow it away and retry
                         * the insertion of the new one.
                         */
                        if (flags & RTF_IFSCOPE) {
                                rt2 = rtalloc1_scoped_locked(dst0, 0,
                                    RTF_CLONING | RTF_PRCLONING, ifscope);
                        } else {
                                rt2 = rtalloc1_locked(dst, 0,
                                    RTF_CLONING | RTF_PRCLONING);
                        }
                        if (rt2 && rt2->rt_parent) {
                                /*
                                 * rnh_lock is held here, so rt_key and
                                 * rt_gateway of rt2 will not change.
                                 */
                                (void) rtrequest_locked(RTM_DELETE, rt_key(rt2),
                                    rt2->rt_gateway, rt_mask(rt2),
                                    rt2->rt_flags, 0);
                                rtfree_locked(rt2);
                                rn = rnh->rnh_addaddr((caddr_t)ndst,
                                    (caddr_t)netmask, rnh, rt->rt_nodes);
                        } else if (rt2) {
                                /* undo the extra ref we got */
                                rtfree_locked(rt2);
                        }
                }

                /*
                 * If it still failed to go into the tree,
                 * then un-make it (this should be a function)
                 */
                if (rn == NULL) {
                        /* Clear gateway route */
                        rt_set_gwroute(rt, rt_key(rt), NULL);
                        if (rt->rt_ifa) {
                                IFA_REMREF(rt->rt_ifa);
                                rt->rt_ifa = NULL;
                        }
                        R_Free(rt_key(rt));
                        RT_UNLOCK(rt);
                        nstat_route_detach(rt);
                        rte_lock_destroy(rt);
                        rte_free(rt);
                        senderr(EEXIST);
                }

                rt->rt_parent = NULL;

                /*
                 * If we got here from RESOLVE, then we are cloning so clone
                 * the rest, and note that we are a clone (and increment the
                 * parent's references).  rnh_lock is still held, which prevents
                 * a lookup from returning the newly-created route.  Hence
                 * holding and releasing the parent's rt_lock while still
                 * holding the route's rt_lock is safe since the new route
                 * is not yet externally visible.
                 */
                if (req == RTM_RESOLVE) {
                        RT_LOCK_SPIN(*ret_nrt);
                        VERIFY((*ret_nrt)->rt_expire == 0 ||
                            (*ret_nrt)->rt_rmx.rmx_expire != 0);
                        VERIFY((*ret_nrt)->rt_expire != 0 ||
                            (*ret_nrt)->rt_rmx.rmx_expire == 0);
                        rt->rt_rmx = (*ret_nrt)->rt_rmx;
                        rt_setexpire(rt, (*ret_nrt)->rt_expire);
                        if ((*ret_nrt)->rt_flags &
                            (RTF_CLONING | RTF_PRCLONING)) {
                                rt->rt_parent = (*ret_nrt);
                                RT_ADDREF_LOCKED(*ret_nrt);
                        }
                        RT_UNLOCK(*ret_nrt);
                }

                /*
                 * if this protocol has something to add to this then
                 * allow it to do that as well.
                 */
                IFA_LOCK_SPIN(ifa);
                ifa_rtrequest = ifa->ifa_rtrequest;
                IFA_UNLOCK(ifa);
                if (ifa_rtrequest != NULL)
                        ifa_rtrequest(req, rt, SA(ret_nrt ? *ret_nrt : NULL));
                IFA_REMREF(ifa);
                ifa = NULL;

                /*
                 * If this is the (non-scoped) default route, record
                 * the interface index used for the primary ifscope.
                 */
                if (rt_primary_default(rt, rt_key(rt))) {
                        set_primary_ifscope(rt_key(rt)->sa_family,
                            rt->rt_ifp->if_index);
                }

                /*
                 * actually return a resultant rtentry and
                 * give the caller a single reference.
                 */
                if (ret_nrt) {
                        *ret_nrt = rt;
                        RT_ADDREF_LOCKED(rt);
                }

                if (af == AF_INET)
                        routegenid_inet_update();
#if INET6
                else if (af == AF_INET6)
                        routegenid_inet6_update();
#endif /* INET6 */

                RT_GENID_SYNC(rt);

                /*
                 * We repeat the same procedures from rt_setgate() here
                 * because they weren't completed when we called it earlier,
                 * since the node was embryonic.
                 */
                if ((rt->rt_flags & RTF_GATEWAY) && rt->rt_gwroute != NULL)
                        rt_set_gwroute(rt, rt_key(rt), rt->rt_gwroute);

                if (req == RTM_ADD &&
                    !(rt->rt_flags & RTF_HOST) && rt_mask(rt) != NULL) {
                        struct rtfc_arg arg;
                        arg.rnh = rnh;
                        arg.rt0 = rt;
                        RT_UNLOCK(rt);
                        rnh->rnh_walktree_from(rnh, rt_key(rt), rt_mask(rt),
                            rt_fixchange, &arg);
                } else {
                        RT_UNLOCK(rt);
                }

                nstat_route_new_entry(rt);
                break;
        }
bad:
        if (ifa)
                IFA_REMREF(ifa);
        return (error);
}
#undef senderr

int
rtrequest(int req, struct sockaddr *dst, struct sockaddr *gateway,
    struct sockaddr *netmask, int flags, struct rtentry **ret_nrt)
{
        int error;
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);
        error = rtrequest_locked(req, dst, gateway, netmask, flags, ret_nrt);
        lck_mtx_unlock(rnh_lock);
        return (error);
}

int
rtrequest_scoped(int req, struct sockaddr *dst, struct sockaddr *gateway,
    struct sockaddr *netmask, int flags, struct rtentry **ret_nrt,
    unsigned int ifscope)
{
        int error;
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
        lck_mtx_lock(rnh_lock);
        error = rtrequest_scoped_locked(req, dst, gateway, netmask, flags,
            ret_nrt, ifscope);
        lck_mtx_unlock(rnh_lock);
        return (error);
}

/*
 * Called from rtrequest(RTM_DELETE, ...) to fix up the route's ``family''
 * (i.e., the routes related to it by the operation of cloning).  This
 * routine is iterated over all potential former-child-routes by way of
 * rnh->rnh_walktree_from() above, and those that actually are children of
 * the late parent (passed in as VP here) are themselves deleted.
 */
static int
rt_fixdelete(struct radix_node *rn, void *vp)
{
        struct rtentry *rt = (struct rtentry *)rn;
        struct rtentry *rt0 = vp;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        RT_LOCK(rt);
        if (rt->rt_parent == rt0 &&
            !(rt->rt_flags & (RTF_CLONING | RTF_PRCLONING))) {
                /*
                 * Safe to drop rt_lock and use rt_key, since holding
                 * rnh_lock here prevents another thread from calling
                 * rt_setgate() on this route.
                 */
                RT_UNLOCK(rt);
                return (rtrequest_locked(RTM_DELETE, rt_key(rt), NULL,
                    rt_mask(rt), rt->rt_flags, NULL));
        }
        RT_UNLOCK(rt);
        return (0);
}

/*
 * This routine is called from rt_setgate() to do the analogous thing for
 * adds and changes.  There is the added complication in this case of a
 * middle insert; i.e., insertion of a new network route between an older
 * network route and (cloned) host routes.  For this reason, a simple check
 * of rt->rt_parent is insufficient; each candidate route must be tested
 * against the (mask, value) of the new route (passed as before in vp)
 * to see if the new route matches it.
 *
 * XXX - it may be possible to do fixdelete() for changes and reserve this
 * routine just for adds.  I'm not sure why I thought it was necessary to do
 * changes this way.
 */
static int
rt_fixchange(struct radix_node *rn, void *vp)
{
        struct rtentry *rt = (struct rtentry *)rn;
        struct rtfc_arg *ap = vp;
        struct rtentry *rt0 = ap->rt0;
        struct radix_node_head *rnh = ap->rnh;
        u_char *xk1, *xm1, *xk2, *xmp;
        int i, len;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        RT_LOCK(rt);

        if (!rt->rt_parent ||
            (rt->rt_flags & (RTF_CLONING | RTF_PRCLONING))) {
                RT_UNLOCK(rt);
                return (0);
        }

        if (rt->rt_parent == rt0)
                goto delete_rt;

        /*
         * There probably is a function somewhere which does this...
         * if not, there should be.
         */
        len = imin(rt_key(rt0)->sa_len, rt_key(rt)->sa_len);

        xk1 = (u_char *)rt_key(rt0);
        xm1 = (u_char *)rt_mask(rt0);
        xk2 = (u_char *)rt_key(rt);

        /*
         * Avoid applying a less specific route; do this only if the parent
         * route (rt->rt_parent) is a network route, since otherwise its mask
         * will be NULL if it is a cloning host route.
         */
        if ((xmp = (u_char *)rt_mask(rt->rt_parent)) != NULL) {
                int mlen = rt_mask(rt->rt_parent)->sa_len;
                if (mlen > rt_mask(rt0)->sa_len) {
                        RT_UNLOCK(rt);
                        return (0);
                }

                for (i = rnh->rnh_treetop->rn_offset; i < mlen; i++) {
                        if ((xmp[i] & ~(xmp[i] ^ xm1[i])) != xmp[i]) {
                                RT_UNLOCK(rt);
                                return (0);
                        }
                }
        }

        for (i = rnh->rnh_treetop->rn_offset; i < len; i++) {
                if ((xk2[i] & xm1[i]) != xk1[i]) {
                        RT_UNLOCK(rt);
                        return (0);
                }
        }

        /*
         * OK, this node is a clone, and matches the node currently being
         * changed/added under the node's mask.  So, get rid of it.
         */
delete_rt:
        /*
         * Safe to drop rt_lock and use rt_key, since holding rnh_lock here
         * prevents another thread from calling rt_setgate() on this route.
         */
        RT_UNLOCK(rt);
        return (rtrequest_locked(RTM_DELETE, rt_key(rt), NULL,
            rt_mask(rt), rt->rt_flags, NULL));
}

/*
 * Round up sockaddr len to multiples of 32-bytes.  This will reduce
 * or even eliminate the need to re-allocate the chunk of memory used
 * for rt_key and rt_gateway in the event the gateway portion changes.
 * Certain code paths (e.g. IPSec) are notorious for caching the address
 * of rt_gateway; this rounding-up would help ensure that the gateway
 * portion never gets deallocated (though it may change contents) and
 * thus greatly simplifies things.
 */
#define SA_SIZE(x) (-(-((uintptr_t)(x)) & -(32)))

/*
 * Sets the gateway and/or gateway route portion of a route; may be
 * called on an existing route to modify the gateway portion.  Both
 * rt_key and rt_gateway are allocated out of the same memory chunk.
 * Route entry lock must be held by caller; this routine will return
 * with the lock held.
 */
int
rt_setgate(struct rtentry *rt, struct sockaddr *dst, struct sockaddr *gate)
{
        int dlen = SA_SIZE(dst->sa_len), glen = SA_SIZE(gate->sa_len);
        struct radix_node_head *rnh = NULL;
        boolean_t loop = FALSE;

        if (dst->sa_family != AF_INET && dst->sa_family != AF_INET6) {
                return (EINVAL);
        }

        rnh = rt_tables[dst->sa_family];
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
        RT_LOCK_ASSERT_HELD(rt);

        /*
         * If this is for a route that is on its way of being removed,
         * or is temporarily frozen, reject the modification request.
         */
        if (rt->rt_flags & RTF_CONDEMNED) {
                return (EBUSY);
        }

        /* Add an extra ref for ourselves */
        RT_ADDREF_LOCKED(rt);

        if (rt->rt_flags & RTF_GATEWAY) {
                if ((dst->sa_len == gate->sa_len) &&
                    (dst->sa_family == AF_INET || dst->sa_family == AF_INET6)) {
                        struct sockaddr_storage dst_ss, gate_ss;

                        (void) sa_copy(dst, &dst_ss, NULL);
                        (void) sa_copy(gate, &gate_ss, NULL);

                        loop = equal(SA(&dst_ss), SA(&gate_ss));
                } else {
                        loop = (dst->sa_len == gate->sa_len &&
                            equal(dst, gate));
                }
        }

        /*
         * A (cloning) network route with the destination equal to the gateway
         * will create an endless loop (see notes below), so disallow it.
         */
        if (((rt->rt_flags & (RTF_HOST|RTF_GATEWAY|RTF_LLINFO)) ==
            RTF_GATEWAY) && loop) {
                /* Release extra ref */
                RT_REMREF_LOCKED(rt);
                return (EADDRNOTAVAIL);
        }

        /*
         * A host route with the destination equal to the gateway
         * will interfere with keeping LLINFO in the routing
         * table, so disallow it.
         */
        if (((rt->rt_flags & (RTF_HOST|RTF_GATEWAY|RTF_LLINFO)) ==
            (RTF_HOST|RTF_GATEWAY)) && loop) {
                /*
                 * The route might already exist if this is an RTM_CHANGE
                 * or a routing redirect, so try to delete it.
                 */
                if (rt_key(rt) != NULL) {
                        /*
                         * Safe to drop rt_lock and use rt_key, rt_gateway,
                         * since holding rnh_lock here prevents another thread
                         * from calling rt_setgate() on this route.
                         */
                        RT_UNLOCK(rt);
                        (void) rtrequest_locked(RTM_DELETE, rt_key(rt),
                            rt->rt_gateway, rt_mask(rt), rt->rt_flags, NULL);
                        RT_LOCK(rt);
                }
                /* Release extra ref */
                RT_REMREF_LOCKED(rt);
                return (EADDRNOTAVAIL);
        }

        /*
         * The destination is not directly reachable.  Get a route
         * to the next-hop gateway and store it in rt_gwroute.
         */
        if (rt->rt_flags & RTF_GATEWAY) {
                struct rtentry *gwrt;
                unsigned int ifscope;

                if (dst->sa_family == AF_INET)
                        ifscope = sin_get_ifscope(dst);
                else if (dst->sa_family == AF_INET6)
                        ifscope = sin6_get_ifscope(dst);
                else
                        ifscope = IFSCOPE_NONE;

                RT_UNLOCK(rt);
                /*
                 * Don't ignore RTF_CLONING, since we prefer that rt_gwroute
                 * points to a clone rather than a cloning route; see above
                 * check for cloning loop avoidance (dst == gate).
                 */
                gwrt = rtalloc1_scoped_locked(gate, 1, RTF_PRCLONING, ifscope);
                if (gwrt != NULL)
                        RT_LOCK_ASSERT_NOTHELD(gwrt);
                RT_LOCK(rt);

                /*
                 * Cloning loop avoidance:
                 *
                 * In the presence of protocol-cloning and bad configuration,
                 * it is possible to get stuck in bottomless mutual recursion
                 * (rtrequest rt_setgate rtalloc1).  We avoid this by not
                 * allowing protocol-cloning to operate for gateways (which
                 * is probably the correct choice anyway), and avoid the
                 * resulting reference loops by disallowing any route to run
                 * through itself as a gateway.  This is obviously mandatory
                 * when we get rt->rt_output().  It implies that a route to
                 * the gateway must already be present in the system in order
                 * for the gateway to be referred to by another route.
                 */
                if (gwrt == rt) {
                        RT_REMREF_LOCKED(gwrt);
                        /* Release extra ref */
                        RT_REMREF_LOCKED(rt);
                        return (EADDRINUSE); /* failure */
                }

                /*
                 * If scoped, the gateway route must use the same interface;
                 * we're holding rnh_lock now, so rt_gateway and rt_ifp of gwrt
                 * should not change and are freely accessible.
                 */
                if (ifscope != IFSCOPE_NONE && (rt->rt_flags & RTF_IFSCOPE) &&
                    gwrt != NULL && gwrt->rt_ifp != NULL &&
                    gwrt->rt_ifp->if_index != ifscope) {
                        rtfree_locked(gwrt);    /* rt != gwrt, no deadlock */
                        /* Release extra ref */
                        RT_REMREF_LOCKED(rt);
                        return ((rt->rt_flags & RTF_HOST) ?
                            EHOSTUNREACH : ENETUNREACH);
                }

                /* Check again since we dropped the lock above */
                if (rt->rt_flags & RTF_CONDEMNED) {
                        if (gwrt != NULL)
                                rtfree_locked(gwrt);
                        /* Release extra ref */
                        RT_REMREF_LOCKED(rt);
                        return (EBUSY);
                }

                /* Set gateway route; callee adds ref to gwrt if non-NULL */
                rt_set_gwroute(rt, dst, gwrt);

                /*
                 * In case the (non-scoped) default route gets modified via
                 * an ICMP redirect, record the interface index used for the
                 * primary ifscope.  Also done in rt_setif() to take care
                 * of the non-redirect cases.
                 */
                if (rt_primary_default(rt, dst) && rt->rt_ifp != NULL) {
                        set_primary_ifscope(dst->sa_family,
                            rt->rt_ifp->if_index);
                }

                /*
                 * Tell the kernel debugger about the new default gateway
                 * if the gateway route uses the primary interface, or
                 * if we are in a transient state before the non-scoped
                 * default gateway is installed (similar to how the system
                 * was behaving in the past).  In future, it would be good
                 * to do all this only when KDP is enabled.
                 */
                if ((dst->sa_family == AF_INET) &&
                    gwrt != NULL && gwrt->rt_gateway->sa_family == AF_LINK &&
                    (gwrt->rt_ifp->if_index == get_primary_ifscope(AF_INET) ||
                    get_primary_ifscope(AF_INET) == IFSCOPE_NONE)) {
                        kdp_set_gateway_mac(SDL((void *)gwrt->rt_gateway)->
                            sdl_data);
                }

                /* Release extra ref from rtalloc1() */
                if (gwrt != NULL)
                        RT_REMREF(gwrt);
        }

        /*
         * Prepare to store the gateway in rt_gateway.  Both dst and gateway
         * are stored one after the other in the same malloc'd chunk.  If we
         * have room, reuse the old buffer since rt_gateway already points
         * to the right place.  Otherwise, malloc a new block and update
         * the 'dst' address and point rt_gateway to the right place.
         */
        if (rt->rt_gateway == NULL || glen > SA_SIZE(rt->rt_gateway->sa_len)) {
                caddr_t new;

                /* The underlying allocation is done with M_WAITOK set */
                R_Malloc(new, caddr_t, dlen + glen);
                if (new == NULL) {
                        /* Clear gateway route */
                        rt_set_gwroute(rt, dst, NULL);
                        /* Release extra ref */
                        RT_REMREF_LOCKED(rt);
                        return (ENOBUFS);
                }

                /*
                 * Copy from 'dst' and not rt_key(rt) because we can get
                 * here to initialize a newly allocated route entry, in
                 * which case rt_key(rt) is NULL (and so does rt_gateway).
                 */
                bzero(new, dlen + glen);
                Bcopy(dst, new, dst->sa_len);
                R_Free(rt_key(rt));     /* free old block; NULL is okay */
                rt->rt_nodes->rn_key = new;
                rt->rt_gateway = (struct sockaddr *)(new + dlen);
        }

        /*
         * Copy the new gateway value into the memory chunk.
         */
        Bcopy(gate, rt->rt_gateway, gate->sa_len);

        /*
         * For consistency between rt_gateway and rt_key(gwrt).
         */
        if ((rt->rt_flags & RTF_GATEWAY) && rt->rt_gwroute != NULL &&
            (rt->rt_gwroute->rt_flags & RTF_IFSCOPE)) {
                if (rt->rt_gateway->sa_family == AF_INET &&
                    rt_key(rt->rt_gwroute)->sa_family == AF_INET) {
                        sin_set_ifscope(rt->rt_gateway,
                            sin_get_ifscope(rt_key(rt->rt_gwroute)));
                } else if (rt->rt_gateway->sa_family == AF_INET6 &&
                    rt_key(rt->rt_gwroute)->sa_family == AF_INET6) {
                        sin6_set_ifscope(rt->rt_gateway,
                            sin6_get_ifscope(rt_key(rt->rt_gwroute)));
                }
        }

        /*
         * This isn't going to do anything useful for host routes, so
         * don't bother.  Also make sure we have a reasonable mask
         * (we don't yet have one during adds).
         */
        if (!(rt->rt_flags & RTF_HOST) && rt_mask(rt) != 0) {
                struct rtfc_arg arg;
                arg.rnh = rnh;
                arg.rt0 = rt;
                RT_UNLOCK(rt);
                rnh->rnh_walktree_from(rnh, rt_key(rt), rt_mask(rt),
                    rt_fixchange, &arg);
                RT_LOCK(rt);
        }

        /* Release extra ref */
        RT_REMREF_LOCKED(rt);
        return (0);
}

#undef SA_SIZE

void
rt_set_gwroute(struct rtentry *rt, struct sockaddr *dst, struct rtentry *gwrt)
{
        boolean_t gwrt_isrouter;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
        RT_LOCK_ASSERT_HELD(rt);

        if (gwrt != NULL)
                RT_ADDREF(gwrt);        /* for this routine */

        /*
         * Get rid of existing gateway route; if rt_gwroute is already
         * set to gwrt, this is slightly redundant (though safe since
         * we held an extra ref above) but makes the code simpler.
         */
        if (rt->rt_gwroute != NULL) {
                struct rtentry *ogwrt = rt->rt_gwroute;

                VERIFY(rt != ogwrt);    /* sanity check */
                rt->rt_gwroute = NULL;
                RT_UNLOCK(rt);
                rtfree_locked(ogwrt);
                RT_LOCK(rt);
                VERIFY(rt->rt_gwroute == NULL);
        }

        /*
         * And associate the new gateway route.
         */
        if ((rt->rt_gwroute = gwrt) != NULL) {
                RT_ADDREF(gwrt);        /* for rt */

                if (rt->rt_flags & RTF_WASCLONED) {
                        /* rt_parent might be NULL if rt is embryonic */
                        gwrt_isrouter = (rt->rt_parent != NULL &&
                            SA_DEFAULT(rt_key(rt->rt_parent)) &&
                            !RT_HOST(rt->rt_parent));
                } else {
                        gwrt_isrouter = (SA_DEFAULT(dst) && !RT_HOST(rt));
                }

                /* If gwrt points to a default router, mark it accordingly */
                if (gwrt_isrouter && RT_HOST(gwrt) &&
                    !(gwrt->rt_flags & RTF_ROUTER)) {
                        RT_LOCK(gwrt);
                        gwrt->rt_flags |= RTF_ROUTER;
                        RT_UNLOCK(gwrt);
                }

                RT_REMREF(gwrt);        /* for this routine */
        }
}

static void
rt_maskedcopy(const struct sockaddr *src, struct sockaddr *dst,
    const struct sockaddr *netmask)
{
        const char *netmaskp = &netmask->sa_data[0];
        const char *srcp = &src->sa_data[0];
        char *dstp = &dst->sa_data[0];
        const char *maskend = (char *)dst
                                    + MIN(netmask->sa_len, src->sa_len);
        const char *srcend = (char *)dst + src->sa_len;

        dst->sa_len = src->sa_len;
        dst->sa_family = src->sa_family;

        while (dstp < maskend)
                *dstp++ = *srcp++ & *netmaskp++;
        if (dstp < srcend)
                memset(dstp, 0, (size_t)(srcend - dstp));
}

/*
 * Lookup an AF_INET/AF_INET6 scoped or non-scoped route depending on the
 * ifscope value passed in by the caller (IFSCOPE_NONE implies non-scoped).
 */
static struct radix_node *
node_lookup(struct sockaddr *dst, struct sockaddr *netmask,
    unsigned int ifscope)
{
        struct radix_node_head *rnh;
        struct radix_node *rn;
        struct sockaddr_storage ss, mask;
        int af = dst->sa_family;
        struct matchleaf_arg ma = { ifscope };
        rn_matchf_t *f = rn_match_ifscope;
        void *w = &ma;

        if (af != AF_INET && af != AF_INET6)
                return (NULL);

        rnh = rt_tables[af];

        /*
         * Transform dst into the internal routing table form,
         * clearing out the scope ID field if ifscope isn't set.
         */
        dst = sa_copy(dst, &ss, (ifscope == IFSCOPE_NONE) ? NULL : &ifscope);

        /* Transform netmask into the internal routing table form */
        if (netmask != NULL)
                netmask = ma_copy(af, netmask, &mask, ifscope);

        if (ifscope == IFSCOPE_NONE)
                f = w = NULL;

        rn = rnh->rnh_lookup_args(dst, netmask, rnh, f, w);
        if (rn != NULL && (rn->rn_flags & RNF_ROOT))
                rn = NULL;

        return (rn);
}

/*
 * Lookup the AF_INET/AF_INET6 non-scoped default route.
 */
static struct radix_node *
node_lookup_default(int af)
{
        struct radix_node_head *rnh;

        VERIFY(af == AF_INET || af == AF_INET6);
        rnh = rt_tables[af];

        return (af == AF_INET ? rnh->rnh_lookup(&sin_def, NULL, rnh) :
            rnh->rnh_lookup(&sin6_def, NULL, rnh));
}

boolean_t
rt_ifa_is_dst(struct sockaddr *dst, struct ifaddr *ifa)
{
        boolean_t result = FALSE;

        if (ifa == NULL || ifa->ifa_addr == NULL)
                return (result);

        IFA_LOCK_SPIN(ifa);

        if (dst->sa_family == ifa->ifa_addr->sa_family &&
            ((dst->sa_family == AF_INET &&
            SIN(dst)->sin_addr.s_addr ==
            SIN(ifa->ifa_addr)->sin_addr.s_addr) ||
            (dst->sa_family == AF_INET6 &&
            SA6_ARE_ADDR_EQUAL(SIN6(dst), SIN6(ifa->ifa_addr)))))
                result = TRUE;

        IFA_UNLOCK(ifa);

        return (result);
}

/*
 * Common routine to lookup/match a route.  It invokes the lookup/matchaddr
 * callback which could be address family-specific.  The main difference
 * between the two (at least for AF_INET/AF_INET6) is that a lookup does
 * not alter the expiring state of a route, whereas a match would unexpire
 * or revalidate the route.
 *
 * The optional scope or interface index property of a route allows for a
 * per-interface route instance.  This permits multiple route entries having
 * the same destination (but not necessarily the same gateway) to exist in
 * the routing table; each of these entries is specific to the corresponding
 * interface.  This is made possible by storing the scope ID value into the
 * radix key, thus making each route entry unique.  These scoped entries
 * exist along with the regular, non-scoped entries in the same radix tree
 * for a given address family (AF_INET/AF_INET6); the scope logically
 * partitions it into multiple per-interface sub-trees.
 *
 * When a scoped route lookup is performed, the routing table is searched for
 * the best match that would result in a route using the same interface as the
 * one associated with the scope (the exception to this are routes that point
 * to the loopback interface).  The search rule follows the longest matching
 * prefix with the additional interface constraint.
 */
static struct rtentry *
rt_lookup_common(boolean_t lookup_only, boolean_t coarse, struct sockaddr *dst,
    struct sockaddr *netmask, struct radix_node_head *rnh, unsigned int ifscope)
{
        struct radix_node *rn0, *rn = NULL;
        int af = dst->sa_family;
        struct sockaddr_storage dst_ss;
        struct sockaddr_storage mask_ss;
        boolean_t dontcare;
#if (DEVELOPMENT || DEBUG)
        char dbuf[MAX_SCOPE_ADDR_STR_LEN], gbuf[MAX_IPv6_STR_LEN];
        char s_dst[MAX_IPv6_STR_LEN], s_netmask[MAX_IPv6_STR_LEN];
#endif
        VERIFY(!coarse || ifscope == IFSCOPE_NONE);

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
#if INET6
        /*
         * While we have rnh_lock held, see if we need to schedule the timer.
         */
        if (nd6_sched_timeout_want)
                nd6_sched_timeout(NULL, NULL);
#endif /* INET6 */

        if (!lookup_only)
                netmask = NULL;

        /*
         * Non-scoped route lookup.
         */
#if INET6
        if (af != AF_INET && af != AF_INET6) {
#else
        if (af != AF_INET) {
#endif /* !INET6 */
                rn = rnh->rnh_matchaddr(dst, rnh);

                /*
                 * Don't return a root node; also, rnh_matchaddr callback
                 * would have done the necessary work to clear RTPRF_OURS
                 * for certain protocol families.
                 */
                if (rn != NULL && (rn->rn_flags & RNF_ROOT))
                        rn = NULL;
                if (rn != NULL) {
                        RT_LOCK_SPIN(RT(rn));
                        if (!(RT(rn)->rt_flags & RTF_CONDEMNED)) {
                                RT_ADDREF_LOCKED(RT(rn));
                                RT_UNLOCK(RT(rn));
                        } else {
                                RT_UNLOCK(RT(rn));
                                rn = NULL;
                        }
                }
                return (RT(rn));
        }

        /* Transform dst/netmask into the internal routing table form */
        dst = sa_copy(dst, &dst_ss, &ifscope);
        if (netmask != NULL)
                netmask = ma_copy(af, netmask, &mask_ss, ifscope);
        dontcare = (ifscope == IFSCOPE_NONE);

#if (DEVELOPMENT || DEBUG)
        if (rt_verbose) {
                if (af == AF_INET)
                        (void) inet_ntop(af, &SIN(dst)->sin_addr.s_addr,
                            s_dst, sizeof (s_dst));
                else
                        (void) inet_ntop(af, &SIN6(dst)->sin6_addr,
                            s_dst, sizeof (s_dst));

                if (netmask != NULL && af == AF_INET)
                        (void) inet_ntop(af, &SIN(netmask)->sin_addr.s_addr,
                            s_netmask, sizeof (s_netmask));
                if (netmask != NULL && af == AF_INET6)
                        (void) inet_ntop(af, &SIN6(netmask)->sin6_addr,
                            s_netmask, sizeof (s_netmask));
                else
                        *s_netmask = '\0';
                printf("%s (%d, %d, %s, %s, %u)\n",
                    __func__, lookup_only, coarse, s_dst, s_netmask, ifscope);
        }
#endif

        /*
         * Scoped route lookup:
         *
         * We first perform a non-scoped lookup for the original result.
         * Afterwards, depending on whether or not the caller has specified
         * a scope, we perform a more specific scoped search and fallback
         * to this original result upon failure.
         */
        rn0 = rn = node_lookup(dst, netmask, IFSCOPE_NONE);

        /*
         * If the caller did not specify a scope, use the primary scope
         * derived from the system's non-scoped default route.  If, for
         * any reason, there is no primary interface, ifscope will be
         * set to IFSCOPE_NONE; if the above lookup resulted in a route,
         * we'll do a more-specific search below, scoped to the interface
         * of that route.
         */
        if (dontcare)
                ifscope = get_primary_ifscope(af);

        /*
         * Keep the original result if either of the following is true:
         *
         *   1) The interface portion of the route has the same interface
         *      index as the scope value and it is marked with RTF_IFSCOPE.
         *   2) The route uses the loopback interface, in which case the
         *      destination (host/net) is local/loopback.
         *
         * Otherwise, do a more specified search using the scope;
         * we're holding rnh_lock now, so rt_ifp should not change.
         */
        if (rn != NULL) {
                struct rtentry *rt = RT(rn);
#if (DEVELOPMENT || DEBUG)
                if (rt_verbose) {
                        rt_str(rt, dbuf, sizeof (dbuf), gbuf, sizeof (gbuf));
                        printf("%s unscoped search %p to %s->%s->%s ifa_ifp %s\n",
                            __func__, rt,
                            dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            (rt->rt_ifa->ifa_ifp != NULL) ?
                            rt->rt_ifa->ifa_ifp->if_xname : "");
                }
#endif
                if (!(rt->rt_ifp->if_flags & IFF_LOOPBACK) ||
                    (rt->rt_flags & RTF_GATEWAY)) {
                        if (rt->rt_ifp->if_index != ifscope) {
                                /*
                                 * Wrong interface; keep the original result
                                 * only if the caller did not specify a scope,
                                 * and do a more specific scoped search using
                                 * the scope of the found route.  Otherwise,
                                 * start again from scratch.
                                 *
                                 * For loopback scope we keep the unscoped
                                 * route for local addresses
                                 */
                                rn = NULL;
                                if (dontcare)
                                        ifscope = rt->rt_ifp->if_index;
                                else if (ifscope != lo_ifp->if_index ||
                                    rt_ifa_is_dst(dst, rt->rt_ifa) == FALSE)
                                        rn0 = NULL;
                        } else if (!(rt->rt_flags & RTF_IFSCOPE)) {
                                /*
                                 * Right interface, except that this route
                                 * isn't marked with RTF_IFSCOPE.  Do a more
                                 * specific scoped search.  Keep the original
                                 * result and return it it in case the scoped
                                 * search fails.
                                 */
                                rn = NULL;
                        }
                }
        }

        /*
         * Scoped search.  Find the most specific entry having the same
         * interface scope as the one requested.  The following will result
         * in searching for the longest prefix scoped match.
         */
        if (rn == NULL) {
                rn = node_lookup(dst, netmask, ifscope);
#if (DEVELOPMENT || DEBUG)
                if (rt_verbose && rn != NULL) {
                        struct rtentry *rt = RT(rn);

                        rt_str(rt, dbuf, sizeof (dbuf), gbuf, sizeof (gbuf));
                        printf("%s scoped search %p to %s->%s->%s ifa %s\n",
                            __func__, rt,
                            dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            (rt->rt_ifa->ifa_ifp != NULL) ?
                            rt->rt_ifa->ifa_ifp->if_xname : "");
                }
#endif
        }
        /*
         * Use the original result if either of the following is true:
         *
         *   1) The scoped search did not yield any result.
         *   2) The caller insists on performing a coarse-grained lookup.
         *   3) The result from the scoped search is a scoped default route,
         *      and the original (non-scoped) result is not a default route,
         *      i.e. the original result is a more specific host/net route.
         *   4) The scoped search yielded a net route but the original
         *      result is a host route, i.e. the original result is treated
         *      as a more specific route.
         */
        if (rn == NULL || coarse || (rn0 != NULL &&
            ((SA_DEFAULT(rt_key(RT(rn))) && !SA_DEFAULT(rt_key(RT(rn0)))) ||
            (!RT_HOST(rn) && RT_HOST(rn0)))))
                rn = rn0;

        /*
         * If we still don't have a route, use the non-scoped default
         * route as long as the interface portion satistifes the scope.
         */
        if (rn == NULL && (rn = node_lookup_default(af)) != NULL &&
            RT(rn)->rt_ifp->if_index != ifscope) {
                rn = NULL;
        }

        if (rn != NULL) {
                /*
                 * Manually clear RTPRF_OURS using rt_validate() and
                 * bump up the reference count after, and not before;
                 * we only get here for AF_INET/AF_INET6.  node_lookup()
                 * has done the check against RNF_ROOT, so we can be sure
                 * that we're not returning a root node here.
                 */
                RT_LOCK_SPIN(RT(rn));
                if (rt_validate(RT(rn))) {
                        RT_ADDREF_LOCKED(RT(rn));
                        RT_UNLOCK(RT(rn));
                } else {
                        RT_UNLOCK(RT(rn));
                        rn = NULL;
                }
        }
#if (DEVELOPMENT || DEBUG)
        if (rt_verbose) {
                if (rn == NULL)
                        printf("%s %u return NULL\n", __func__, ifscope);
                else {
                        struct rtentry *rt = RT(rn);

                        rt_str(rt, dbuf, sizeof (dbuf), gbuf, sizeof (gbuf));

                        printf("%s %u return %p to %s->%s->%s ifa_ifp %s\n",
                            __func__, ifscope, rt,
                            dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            (rt->rt_ifa->ifa_ifp != NULL) ?
                            rt->rt_ifa->ifa_ifp->if_xname : "");
                }
        }
#endif
        return (RT(rn));
}

struct rtentry *
rt_lookup(boolean_t lookup_only, struct sockaddr *dst, struct sockaddr *netmask,
    struct radix_node_head *rnh, unsigned int ifscope)
{
        return (rt_lookup_common(lookup_only, FALSE, dst, netmask,
            rnh, ifscope));
}

struct rtentry *
rt_lookup_coarse(boolean_t lookup_only, struct sockaddr *dst,
    struct sockaddr *netmask, struct radix_node_head *rnh)
{
        return (rt_lookup_common(lookup_only, TRUE, dst, netmask,
            rnh, IFSCOPE_NONE));
}

boolean_t
rt_validate(struct rtentry *rt)
{
        RT_LOCK_ASSERT_HELD(rt);

        if ((rt->rt_flags & (RTF_UP | RTF_CONDEMNED)) == RTF_UP) {
                int af = rt_key(rt)->sa_family;

                if (af == AF_INET)
                        (void) in_validate(RN(rt));
                else if (af == AF_INET6)
                        (void) in6_validate(RN(rt));
        } else {
                rt = NULL;
        }

        return (rt != NULL);
}

/*
 * Set up a routing table entry, normally
 * for an interface.
 */
int
rtinit(struct ifaddr *ifa, int cmd, int flags)
{
        int error;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);

        lck_mtx_lock(rnh_lock);
        error = rtinit_locked(ifa, cmd, flags);
        lck_mtx_unlock(rnh_lock);

        return (error);
}

int
rtinit_locked(struct ifaddr *ifa, int cmd, int flags)
{
        struct radix_node_head *rnh;
        uint8_t nbuf[128];      /* long enough for IPv6 */
#if (DEVELOPMENT || DEBUG)
        char dbuf[MAX_IPv6_STR_LEN], gbuf[MAX_IPv6_STR_LEN];
        char abuf[MAX_IPv6_STR_LEN];
#endif
        struct rtentry *rt = NULL;
        struct sockaddr *dst;
        struct sockaddr *netmask;
        int error = 0;

        /*
         * Holding rnh_lock here prevents the possibility of ifa from
         * changing (e.g. in_ifinit), so it is safe to access its
         * ifa_{dst}addr (here and down below) without locking.
         */
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        if (flags & RTF_HOST) {
                dst = ifa->ifa_dstaddr;
                netmask = NULL;
        } else {
                dst = ifa->ifa_addr;
                netmask = ifa->ifa_netmask;
        }

        if (dst->sa_len == 0) {
                log(LOG_ERR, "%s: %s failed, invalid dst sa_len %d\n",
                    __func__, rtm2str(cmd), dst->sa_len);
                error = EINVAL;
                goto done;
        }
        if (netmask != NULL && netmask->sa_len > sizeof (nbuf)) {
                log(LOG_ERR, "%s: %s failed, mask sa_len %d too large\n",
                    __func__, rtm2str(cmd), dst->sa_len);
                error = EINVAL;
                goto done;
        }

#if (DEVELOPMENT || DEBUG)
        if (dst->sa_family == AF_INET) {
                (void) inet_ntop(AF_INET, &SIN(dst)->sin_addr.s_addr,
                    abuf, sizeof (abuf));
        }
#if INET6
        else if (dst->sa_family == AF_INET6) {
                (void) inet_ntop(AF_INET6, &SIN6(dst)->sin6_addr,
                    abuf, sizeof (abuf));
        }
#endif /* INET6 */
#endif /* (DEVELOPMENT || DEBUG) */     

        if ((rnh = rt_tables[dst->sa_family]) == NULL) {
                error = EINVAL;
                goto done;
        }

        /*
         * If it's a delete, check that if it exists, it's on the correct
         * interface or we might scrub a route to another ifa which would
         * be confusing at best and possibly worse.
         */
        if (cmd == RTM_DELETE) {
                /*
                 * It's a delete, so it should already exist..
                 * If it's a net, mask off the host bits
                 * (Assuming we have a mask)
                 */
                if (netmask != NULL) {
                        rt_maskedcopy(dst, SA(nbuf), netmask);
                        dst = SA(nbuf);
                }
                /*
                 * Get an rtentry that is in the routing tree and contains
                 * the correct info.  Note that we perform a coarse-grained
                 * lookup here, in case there is a scoped variant of the
                 * subnet/prefix route which we should ignore, as we never
                 * add a scoped subnet/prefix route as part of adding an
                 * interface address.
                 */
                rt = rt_lookup_coarse(TRUE, dst, NULL, rnh);
                if (rt != NULL) {
#if (DEVELOPMENT || DEBUG)
                        rt_str(rt, dbuf, sizeof (dbuf), gbuf, sizeof (gbuf));
#endif                  
                        /*
                         * Ok so we found the rtentry. it has an extra reference
                         * for us at this stage. we won't need that so
                         * lop that off now.
                         */
                        RT_LOCK(rt);
                        if (rt->rt_ifa != ifa) {
                                /*
                                 * If the interface address in the rtentry
                                 * doesn't match the interface we are using,
                                 * then we don't want to delete it, so return
                                 * an error.  This seems to be the only point
                                 * of this whole RTM_DELETE clause.
                                 */
#if (DEVELOPMENT || DEBUG)
                                if (rt_verbose) {
                                        log(LOG_DEBUG, "%s: not removing "
                                            "route to %s->%s->%s, flags %b, "
                                            "ifaddr %s, rt_ifa 0x%llx != "
                                            "ifa 0x%llx\n", __func__, dbuf,
                                            gbuf, ((rt->rt_ifp != NULL) ?
                                            rt->rt_ifp->if_xname : ""),
                                            rt->rt_flags, RTF_BITS, abuf,
                                            (uint64_t)VM_KERNEL_ADDRPERM(
                                            rt->rt_ifa),
                                            (uint64_t)VM_KERNEL_ADDRPERM(ifa));
                                }
#endif /* (DEVELOPMENT || DEBUG) */
                                RT_REMREF_LOCKED(rt);
                                RT_UNLOCK(rt);
                                rt = NULL;
                                error = ((flags & RTF_HOST) ?
                                    EHOSTUNREACH : ENETUNREACH);
                                goto done;
                        } else if (rt->rt_flags & RTF_STATIC) {
                                /*
                                 * Don't remove the subnet/prefix route if
                                 * this was manually added from above.
                                 */
#if (DEVELOPMENT || DEBUG)
                                if (rt_verbose) {
                                        log(LOG_DEBUG, "%s: not removing "
                                            "static route to %s->%s->%s, "
                                            "flags %b, ifaddr %s\n", __func__,
                                            dbuf, gbuf, ((rt->rt_ifp != NULL) ?
                                            rt->rt_ifp->if_xname : ""),
                                            rt->rt_flags, RTF_BITS, abuf);
                                }
#endif /* (DEVELOPMENT || DEBUG) */
                                RT_REMREF_LOCKED(rt);
                                RT_UNLOCK(rt);
                                rt = NULL;
                                error = EBUSY;
                                goto done;
                        }
#if (DEVELOPMENT || DEBUG)
                        if (rt_verbose) {
                                log(LOG_DEBUG, "%s: removing route to "
                                    "%s->%s->%s, flags %b, ifaddr %s\n",
                                    __func__, dbuf, gbuf,
                                    ((rt->rt_ifp != NULL) ?
                                    rt->rt_ifp->if_xname : ""),
                                    rt->rt_flags, RTF_BITS, abuf);
                        }
#endif /* (DEVELOPMENT || DEBUG) */
                        RT_REMREF_LOCKED(rt);
                        RT_UNLOCK(rt);
                        rt = NULL;
                }
        }
        /*
         * Do the actual request
         */
        if ((error = rtrequest_locked(cmd, dst, ifa->ifa_addr, netmask,
            flags | ifa->ifa_flags, &rt)) != 0)
                goto done;

        VERIFY(rt != NULL);
#if (DEVELOPMENT || DEBUG)
        rt_str(rt, dbuf, sizeof (dbuf), gbuf, sizeof (gbuf));
#endif /* (DEVELOPMENT || DEBUG) */
        switch (cmd) {
        case RTM_DELETE:
                /*
                 * If we are deleting, and we found an entry, then it's
                 * been removed from the tree.   Notify any listening
                 * routing agents of the change and throw it away.
                 */
                RT_LOCK(rt);
                rt_newaddrmsg(cmd, ifa, error, rt);
                RT_UNLOCK(rt);
#if (DEVELOPMENT || DEBUG)
                if (rt_verbose) {
                        log(LOG_DEBUG, "%s: removed route to %s->%s->%s, "
                            "flags %b, ifaddr %s\n", __func__, dbuf, gbuf,
                            ((rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : ""),
                            rt->rt_flags, RTF_BITS, abuf);
                }
#endif /* (DEVELOPMENT || DEBUG) */
                rtfree_locked(rt);
                break;

        case RTM_ADD:
                /*
                 * We are adding, and we have a returned routing entry.
                 * We need to sanity check the result.  If it came back
                 * with an unexpected interface, then it must have already
                 * existed or something.
                 */
                RT_LOCK(rt);
                if (rt->rt_ifa != ifa) {
                        void (*ifa_rtrequest)
                            (int, struct rtentry *, struct sockaddr *);
#if (DEVELOPMENT || DEBUG)
                        if (rt_verbose) {
                                if (!(rt->rt_ifa->ifa_ifp->if_flags &
                                    (IFF_POINTOPOINT|IFF_LOOPBACK))) {
                                        log(LOG_ERR, "%s: %s route to %s->%s->%s, "
                                            "flags %b, ifaddr %s, rt_ifa 0x%llx != "
                                            "ifa 0x%llx\n", __func__, rtm2str(cmd),
                                            dbuf, gbuf, ((rt->rt_ifp != NULL) ?
                                                rt->rt_ifp->if_xname : ""), rt->rt_flags,
                                            RTF_BITS, abuf,
                                            (uint64_t)VM_KERNEL_ADDRPERM(rt->rt_ifa),
                                            (uint64_t)VM_KERNEL_ADDRPERM(ifa));
                                }

                                log(LOG_DEBUG, "%s: %s route to %s->%s->%s, "
                                    "flags %b, ifaddr %s, rt_ifa was 0x%llx "
                                    "now 0x%llx\n", __func__, rtm2str(cmd),
                                    dbuf, gbuf, ((rt->rt_ifp != NULL) ?
                                    rt->rt_ifp->if_xname : ""), rt->rt_flags,
                                    RTF_BITS, abuf,
                                    (uint64_t)VM_KERNEL_ADDRPERM(rt->rt_ifa),
                                    (uint64_t)VM_KERNEL_ADDRPERM(ifa));
                        }
#endif /* (DEVELOPMENT || DEBUG) */

                        /*
                         * Ask that the protocol in question
                         * remove anything it has associated with
                         * this route and ifaddr.
                         */
                        ifa_rtrequest = rt->rt_ifa->ifa_rtrequest;
                        if (ifa_rtrequest != NULL)
                                ifa_rtrequest(RTM_DELETE, rt, NULL);
                        /*
                         * Set the route's ifa.
                         */
                        rtsetifa(rt, ifa);

                        if (rt->rt_ifp != ifa->ifa_ifp) {
                                /*
                                 * Purge any link-layer info caching.
                                 */
                                if (rt->rt_llinfo_purge != NULL)
                                        rt->rt_llinfo_purge(rt);
                                /*
                                 * Adjust route ref count for the interfaces.
                                 */
                                if (rt->rt_if_ref_fn != NULL) {
                                        rt->rt_if_ref_fn(ifa->ifa_ifp, 1);
                                        rt->rt_if_ref_fn(rt->rt_ifp, -1);
                                }
                        }

                        /*
                         * And substitute in references to the ifaddr
                         * we are adding.
                         */
                        rt->rt_ifp = ifa->ifa_ifp;
                        /*
                         * If rmx_mtu is not locked, update it
                         * to the MTU used by the new interface.
                         */
                        if (!(rt->rt_rmx.rmx_locks & RTV_MTU))
                                rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;

                        /*
                         * Now ask the protocol to check if it needs
                         * any special processing in its new form.
                         */
                        ifa_rtrequest = ifa->ifa_rtrequest;
                        if (ifa_rtrequest != NULL)
                                ifa_rtrequest(RTM_ADD, rt, NULL);
                } else {
#if (DEVELOPMENT || DEBUG)
                        if (rt_verbose) {
                                log(LOG_DEBUG, "%s: added route to %s->%s->%s, "
                                    "flags %b, ifaddr %s\n", __func__, dbuf,
                                    gbuf, ((rt->rt_ifp != NULL) ?
                                    rt->rt_ifp->if_xname : ""), rt->rt_flags,
                                    RTF_BITS, abuf);
                        }
#endif /* (DEVELOPMENT || DEBUG) */
                }
                /*
                 * notify any listenning routing agents of the change
                 */
                rt_newaddrmsg(cmd, ifa, error, rt);
                /*
                 * We just wanted to add it; we don't actually need a
                 * reference.  This will result in a route that's added
                 * to the routing table without a reference count.  The
                 * RTM_DELETE code will do the necessary step to adjust
                 * the reference count at deletion time.
                 */
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                break;

        default:
                VERIFY(0);
                /* NOTREACHED */
        }
done:
        return (error);
}

static void
rt_set_idleref(struct rtentry *rt)
{
        RT_LOCK_ASSERT_HELD(rt);

        /*
         * We currently keep idle refcnt only on unicast cloned routes
         * that aren't marked with RTF_NOIFREF.
         */
        if (rt->rt_parent != NULL && !(rt->rt_flags &
            (RTF_NOIFREF|RTF_BROADCAST | RTF_MULTICAST)) &&
            (rt->rt_flags & (RTF_UP|RTF_WASCLONED|RTF_IFREF)) ==
            (RTF_UP|RTF_WASCLONED)) {
                rt_clear_idleref(rt);   /* drop existing refcnt if any  */
                rt->rt_if_ref_fn = rte_if_ref;
                /* Become a regular mutex, just in case */
                RT_CONVERT_LOCK(rt);
                rt->rt_if_ref_fn(rt->rt_ifp, 1);
                rt->rt_flags |= RTF_IFREF;
        }
}

void
rt_clear_idleref(struct rtentry *rt)
{
        RT_LOCK_ASSERT_HELD(rt);

        if (rt->rt_if_ref_fn != NULL) {
                VERIFY((rt->rt_flags & (RTF_NOIFREF | RTF_IFREF)) == RTF_IFREF);
                /* Become a regular mutex, just in case */
                RT_CONVERT_LOCK(rt);
                rt->rt_if_ref_fn(rt->rt_ifp, -1);
                rt->rt_flags &= ~RTF_IFREF;
                rt->rt_if_ref_fn = NULL;
        }
}

void
rt_set_proxy(struct rtentry *rt, boolean_t set)
{
        lck_mtx_lock(rnh_lock);
        RT_LOCK(rt);
        /*
         * Search for any cloned routes which might have
         * been formed from this node, and delete them.
         */
        if (rt->rt_flags & (RTF_CLONING | RTF_PRCLONING)) {
                struct radix_node_head *rnh = rt_tables[rt_key(rt)->sa_family];

                if (set)
                        rt->rt_flags |= RTF_PROXY;
                else
                        rt->rt_flags &= ~RTF_PROXY;

                RT_UNLOCK(rt);
                if (rnh != NULL && rt_mask(rt)) {
                        rnh->rnh_walktree_from(rnh, rt_key(rt), rt_mask(rt),
                            rt_fixdelete, rt);
                }
        } else {
                RT_UNLOCK(rt);
        }
        lck_mtx_unlock(rnh_lock);
}

static void
rte_lock_init(struct rtentry *rt)
{
        lck_mtx_init(&rt->rt_lock, rte_mtx_grp, rte_mtx_attr);
}

static void
rte_lock_destroy(struct rtentry *rt)
{
        RT_LOCK_ASSERT_NOTHELD(rt);
        lck_mtx_destroy(&rt->rt_lock, rte_mtx_grp);
}

void
rt_lock(struct rtentry *rt, boolean_t spin)
{
        RT_LOCK_ASSERT_NOTHELD(rt);
        if (spin)
                lck_mtx_lock_spin(&rt->rt_lock);
        else
                lck_mtx_lock(&rt->rt_lock);
        if (rte_debug & RTD_DEBUG)
                rte_lock_debug((struct rtentry_dbg *)rt);
}

void
rt_unlock(struct rtentry *rt)
{
        if (rte_debug & RTD_DEBUG)
                rte_unlock_debug((struct rtentry_dbg *)rt);
        lck_mtx_unlock(&rt->rt_lock);

}

static inline void
rte_lock_debug(struct rtentry_dbg *rte)
{
        uint32_t idx;

        RT_LOCK_ASSERT_HELD((struct rtentry *)rte);
        idx = atomic_add_32_ov(&rte->rtd_lock_cnt, 1) % CTRACE_HIST_SIZE;
        if (rte_debug & RTD_TRACE)
                ctrace_record(&rte->rtd_lock[idx]);
}

static inline void
rte_unlock_debug(struct rtentry_dbg *rte)
{
        uint32_t idx;

        RT_LOCK_ASSERT_HELD((struct rtentry *)rte);
        idx = atomic_add_32_ov(&rte->rtd_unlock_cnt, 1) % CTRACE_HIST_SIZE;
        if (rte_debug & RTD_TRACE)
                ctrace_record(&rte->rtd_unlock[idx]);
}

static struct rtentry *
rte_alloc(void)
{
        if (rte_debug & RTD_DEBUG)
                return (rte_alloc_debug());

        return ((struct rtentry *)zalloc(rte_zone));
}

static void
rte_free(struct rtentry *p)
{
        if (rte_debug & RTD_DEBUG) {
                rte_free_debug(p);
                return;
        }

        if (p->rt_refcnt != 0) {
                panic("rte_free: rte=%p refcnt=%d non-zero\n", p, p->rt_refcnt);
                /* NOTREACHED */
        }

        zfree(rte_zone, p);
}

static void
rte_if_ref(struct ifnet *ifp, int cnt)
{
        struct kev_msg ev_msg;
        struct net_event_data ev_data;
        uint32_t old;

        /* Force cnt to 1 increment/decrement */
        if (cnt < -1 || cnt > 1) {
                panic("%s: invalid count argument (%d)", __func__, cnt);
                /* NOTREACHED */
        }
        old = atomic_add_32_ov(&ifp->if_route_refcnt, cnt);
        if (cnt < 0 && old == 0) {
                panic("%s: ifp=%p negative route refcnt!", __func__, ifp);
                /* NOTREACHED */
        }
        /*
         * The following is done without first holding the ifnet lock,
         * for performance reasons.  The relevant ifnet fields, with
         * the exception of the if_idle_flags, are never changed
         * during the lifetime of the ifnet.  The if_idle_flags
         * may possibly be modified, so in the event that the value
         * is stale because IFRF_IDLE_NOTIFY was cleared, we'd end up
         * sending the event anyway.  This is harmless as it is just
         * a notification to the monitoring agent in user space, and
         * it is expected to check via SIOCGIFGETRTREFCNT again anyway.
         */
        if ((ifp->if_idle_flags & IFRF_IDLE_NOTIFY) && cnt < 0 && old == 1) {
                bzero(&ev_msg, sizeof (ev_msg));
                bzero(&ev_data, sizeof (ev_data));

                ev_msg.vendor_code      = KEV_VENDOR_APPLE;
                ev_msg.kev_class        = KEV_NETWORK_CLASS;
                ev_msg.kev_subclass     = KEV_DL_SUBCLASS;
                ev_msg.event_code       = KEV_DL_IF_IDLE_ROUTE_REFCNT;

                strlcpy(&ev_data.if_name[0], ifp->if_name, IFNAMSIZ);

                ev_data.if_family       = ifp->if_family;
                ev_data.if_unit         = ifp->if_unit;
                ev_msg.dv[0].data_length = sizeof (struct net_event_data);
                ev_msg.dv[0].data_ptr   = &ev_data;

                dlil_post_complete_msg(NULL, &ev_msg);
        }
}

static inline struct rtentry *
rte_alloc_debug(void)
{
        struct rtentry_dbg *rte;

        rte = ((struct rtentry_dbg *)zalloc(rte_zone));
        if (rte != NULL) {
                bzero(rte, sizeof (*rte));
                if (rte_debug & RTD_TRACE)
                        ctrace_record(&rte->rtd_alloc);
                rte->rtd_inuse = RTD_INUSE;
        }
        return ((struct rtentry *)rte);
}

static inline void
rte_free_debug(struct rtentry *p)
{
        struct rtentry_dbg *rte = (struct rtentry_dbg *)p;

        if (p->rt_refcnt != 0) {
                panic("rte_free: rte=%p refcnt=%d\n", p, p->rt_refcnt);
                /* NOTREACHED */
        }
        if (rte->rtd_inuse == RTD_FREED) {
                panic("rte_free: double free rte=%p\n", rte);
                /* NOTREACHED */
        } else if (rte->rtd_inuse != RTD_INUSE) {
                panic("rte_free: corrupted rte=%p\n", rte);
                /* NOTREACHED */
        }
        bcopy((caddr_t)p, (caddr_t)&rte->rtd_entry_saved, sizeof (*p));
        /* Preserve rt_lock to help catch use-after-free cases */
        bzero((caddr_t)p, offsetof(struct rtentry, rt_lock));

        rte->rtd_inuse = RTD_FREED;

        if (rte_debug & RTD_TRACE)
                ctrace_record(&rte->rtd_free);

        if (!(rte_debug & RTD_NO_FREE))
                zfree(rte_zone, p);
}

void
ctrace_record(ctrace_t *tr)
{
        tr->th = current_thread();
        bzero(tr->pc, sizeof (tr->pc));
        (void) OSBacktrace(tr->pc, CTRACE_STACK_SIZE);
}

void
route_copyout(struct route *dst, const struct route *src, size_t length)
{
        /* Copy everything (rt, srcif, flags, dst) from src */
        bcopy(src, dst, length);

        /* Hold one reference for the local copy of struct route */
        if (dst->ro_rt != NULL)
                RT_ADDREF(dst->ro_rt);

        /* Hold one reference for the local copy of struct ifaddr */
        if (dst->ro_srcia != NULL)
                IFA_ADDREF(dst->ro_srcia);
}

void
route_copyin(struct route *src, struct route *dst, size_t length)
{
        /* No cached route at the destination? */
        if (dst->ro_rt == NULL) {
                /*
                 * Ditch the address in the cached copy (dst) since
                 * we're about to take everything there is in src.
                 */
                if (dst->ro_srcia != NULL)
                        IFA_REMREF(dst->ro_srcia);
                /*
                 * Copy everything (rt, srcia, flags, dst) from src; the
                 * references to rt and/or srcia were held at the time
                 * of storage and are kept intact.
                 */
                bcopy(src, dst, length);
        } else if (src->ro_rt != NULL) {
                /*
                 * If the same, update srcia and flags, and ditch the route
                 * in the local copy.  Else ditch the one that is currently
                 * cached, and cache the new route.
                 */
                if (dst->ro_rt == src->ro_rt) {
                        dst->ro_flags = src->ro_flags;
                        if (dst->ro_srcia != src->ro_srcia) {
                                if (dst->ro_srcia != NULL)
                                        IFA_REMREF(dst->ro_srcia);
                                dst->ro_srcia = src->ro_srcia;
                        } else if (src->ro_srcia != NULL) {
                                IFA_REMREF(src->ro_srcia);
                        }
                        rtfree(src->ro_rt);
                } else {
                        rtfree(dst->ro_rt);
                        if (dst->ro_srcia != NULL)
                                IFA_REMREF(dst->ro_srcia);
                        bcopy(src, dst, length);
                }
        } else if (src->ro_srcia != NULL) {
                /*
                 * Ditch src address in the local copy (src) since we're
                 * not caching the route entry anyway (ro_rt is NULL).
                 */
                IFA_REMREF(src->ro_srcia);
        }

        /* This function consumes the references on src */
        src->ro_rt = NULL;
        src->ro_srcia = NULL;
}

/*
 * route_to_gwroute will find the gateway route for a given route.
 *
 * If the route is down, look the route up again.
 * If the route goes through a gateway, get the route to the gateway.
 * If the gateway route is down, look it up again.
 * If the route is set to reject, verify it hasn't expired.
 *
 * If the returned route is non-NULL, the caller is responsible for
 * releasing the reference and unlocking the route.
 */
#define senderr(e) { error = (e); goto bad; }
errno_t
route_to_gwroute(const struct sockaddr *net_dest, struct rtentry *hint0,
    struct rtentry **out_route)
{
        uint64_t timenow;
        struct rtentry *rt = hint0, *hint = hint0;
        errno_t error = 0;
        unsigned int ifindex;
        boolean_t gwroute;

        *out_route = NULL;

        if (rt == NULL)
                return (0);

        /*
         * Next hop determination.  Because we may involve the gateway route
         * in addition to the original route, locking is rather complicated.
         * The general concept is that regardless of whether the route points
         * to the original route or to the gateway route, this routine takes
         * an extra reference on such a route.  This extra reference will be
         * released at the end.
         *
         * Care must be taken to ensure that the "hint0" route never gets freed
         * via rtfree(), since the caller may have stored it inside a struct
         * route with a reference held for that placeholder.
         */
        RT_LOCK_SPIN(rt);
        ifindex = rt->rt_ifp->if_index;
        RT_ADDREF_LOCKED(rt);
        if (!(rt->rt_flags & RTF_UP)) {
                RT_REMREF_LOCKED(rt);
                RT_UNLOCK(rt);
                /* route is down, find a new one */
                hint = rt = rtalloc1_scoped((struct sockaddr *)
                    (size_t)net_dest, 1, 0, ifindex);
                if (hint != NULL) {
                        RT_LOCK_SPIN(rt);
                        ifindex = rt->rt_ifp->if_index;
                } else {
                        senderr(EHOSTUNREACH);
                }
        }

        /*
         * We have a reference to "rt" by now; it will either
         * be released or freed at the end of this routine.
         */
        RT_LOCK_ASSERT_HELD(rt);
        if ((gwroute = (rt->rt_flags & RTF_GATEWAY))) {
                struct rtentry *gwrt = rt->rt_gwroute;
                struct sockaddr_storage ss;
                struct sockaddr *gw = (struct sockaddr *)&ss;

                VERIFY(rt == hint);
                RT_ADDREF_LOCKED(hint);

                /* If there's no gateway rt, look it up */
                if (gwrt == NULL) {
                        bcopy(rt->rt_gateway, gw, MIN(sizeof (ss),
                            rt->rt_gateway->sa_len));
                        RT_UNLOCK(rt);
                        goto lookup;
                }
                /* Become a regular mutex */
                RT_CONVERT_LOCK(rt);

                /*
                 * Take gwrt's lock while holding route's lock;
                 * this is okay since gwrt never points back
                 * to "rt", so no lock ordering issues.
                 */
                RT_LOCK_SPIN(gwrt);
                if (!(gwrt->rt_flags & RTF_UP)) {
                        rt->rt_gwroute = NULL;
                        RT_UNLOCK(gwrt);
                        bcopy(rt->rt_gateway, gw, MIN(sizeof (ss),
                            rt->rt_gateway->sa_len));
                        RT_UNLOCK(rt);
                        rtfree(gwrt);
lookup:
                        lck_mtx_lock(rnh_lock);
                        gwrt = rtalloc1_scoped_locked(gw, 1, 0, ifindex);

                        RT_LOCK(rt);
                        /*
                         * Bail out if the route is down, no route
                         * to gateway, circular route, or if the
                         * gateway portion of "rt" has changed.
                         */
                        if (!(rt->rt_flags & RTF_UP) || gwrt == NULL ||
                            gwrt == rt || !equal(gw, rt->rt_gateway)) {
                                if (gwrt == rt) {
                                        RT_REMREF_LOCKED(gwrt);
                                        gwrt = NULL;
                                }
                                VERIFY(rt == hint);
                                RT_REMREF_LOCKED(hint);
                                hint = NULL;
                                RT_UNLOCK(rt);
                                if (gwrt != NULL)
                                        rtfree_locked(gwrt);
                                lck_mtx_unlock(rnh_lock);
                                senderr(EHOSTUNREACH);
                        }
                        VERIFY(gwrt != NULL);
                        /*
                         * Set gateway route; callee adds ref to gwrt;
                         * gwrt has an extra ref from rtalloc1() for
                         * this routine.
                         */
                        rt_set_gwroute(rt, rt_key(rt), gwrt);
                        VERIFY(rt == hint);
                        RT_REMREF_LOCKED(rt);   /* hint still holds a refcnt */
                        RT_UNLOCK(rt);
                        lck_mtx_unlock(rnh_lock);
                        rt = gwrt;
                } else {
                        RT_ADDREF_LOCKED(gwrt);
                        RT_UNLOCK(gwrt);
                        VERIFY(rt == hint);
                        RT_REMREF_LOCKED(rt);   /* hint still holds a refcnt */
                        RT_UNLOCK(rt);
                        rt = gwrt;
                }
                VERIFY(rt == gwrt && rt != hint);

                /*
                 * This is an opportunity to revalidate the parent route's
                 * rt_gwroute, in case it now points to a dead route entry.
                 * Parent route won't go away since the clone (hint) holds
                 * a reference to it.  rt == gwrt.
                 */
                RT_LOCK_SPIN(hint);
                if ((hint->rt_flags & (RTF_WASCLONED | RTF_UP)) ==
                    (RTF_WASCLONED | RTF_UP)) {
                        struct rtentry *prt = hint->rt_parent;
                        VERIFY(prt != NULL);

                        RT_CONVERT_LOCK(hint);
                        RT_ADDREF(prt);
                        RT_UNLOCK(hint);
                        rt_revalidate_gwroute(prt, rt);
                        RT_REMREF(prt);
                } else {
                        RT_UNLOCK(hint);
                }

                /* Clean up "hint" now; see notes above regarding hint0 */
                if (hint == hint0)
                        RT_REMREF(hint);
                else
                        rtfree(hint);
                hint = NULL;

                /* rt == gwrt; if it is now down, give up */
                RT_LOCK_SPIN(rt);
                if (!(rt->rt_flags & RTF_UP)) {
                        RT_UNLOCK(rt);
                        senderr(EHOSTUNREACH);
                }
        }

        if (rt->rt_flags & RTF_REJECT) {
                VERIFY(rt->rt_expire == 0 || rt->rt_rmx.rmx_expire != 0);
                VERIFY(rt->rt_expire != 0 || rt->rt_rmx.rmx_expire == 0);
                timenow = net_uptime();
                if (rt->rt_expire == 0 || timenow < rt->rt_expire) {
                        RT_UNLOCK(rt);
                        senderr(!gwroute ? EHOSTDOWN : EHOSTUNREACH);
                }
        }

        /* Become a regular mutex */
        RT_CONVERT_LOCK(rt);

        /* Caller is responsible for cleaning up "rt" */
        *out_route = rt;
        return (0);

bad:
        /* Clean up route (either it is "rt" or "gwrt") */
        if (rt != NULL) {
                RT_LOCK_SPIN(rt);
                if (rt == hint0) {
                        RT_REMREF_LOCKED(rt);
                        RT_UNLOCK(rt);
                } else {
                        RT_UNLOCK(rt);
                        rtfree(rt);
                }
        }
        return (error);
}
#undef senderr

void
rt_revalidate_gwroute(struct rtentry *rt, struct rtentry *gwrt)
{
        VERIFY(gwrt != NULL);

        RT_LOCK_SPIN(rt);
        if ((rt->rt_flags & (RTF_GATEWAY | RTF_UP)) == (RTF_GATEWAY | RTF_UP) &&
            rt->rt_ifp == gwrt->rt_ifp && rt->rt_gateway->sa_family ==
            rt_key(gwrt)->sa_family && (rt->rt_gwroute == NULL ||
            !(rt->rt_gwroute->rt_flags & RTF_UP))) {
                boolean_t isequal;
                VERIFY(rt->rt_flags & (RTF_CLONING | RTF_PRCLONING));

                if (rt->rt_gateway->sa_family == AF_INET ||
                    rt->rt_gateway->sa_family == AF_INET6) {
                        struct sockaddr_storage key_ss, gw_ss;
                        /*
                         * We need to compare rt_key and rt_gateway; create
                         * local copies to get rid of any ifscope association.
                         */
                        (void) sa_copy(rt_key(gwrt), &key_ss, NULL);
                        (void) sa_copy(rt->rt_gateway, &gw_ss, NULL);

                        isequal = equal(SA(&key_ss), SA(&gw_ss));
                } else {
                        isequal = equal(rt_key(gwrt), rt->rt_gateway);
                }

                /* If they are the same, update gwrt */
                if (isequal) {
                        RT_UNLOCK(rt);
                        lck_mtx_lock(rnh_lock);
                        RT_LOCK(rt);
                        rt_set_gwroute(rt, rt_key(rt), gwrt);
                        RT_UNLOCK(rt);
                        lck_mtx_unlock(rnh_lock);
                } else {
                        RT_UNLOCK(rt);
                }
        } else {
                RT_UNLOCK(rt);
        }
}

static void
rt_str4(struct rtentry *rt, char *ds, uint32_t dslen, char *gs, uint32_t gslen)
{
        VERIFY(rt_key(rt)->sa_family == AF_INET);

        if (ds != NULL) {
                (void) inet_ntop(AF_INET,
                    &SIN(rt_key(rt))->sin_addr.s_addr, ds, dslen);
                if (dslen >= MAX_SCOPE_ADDR_STR_LEN &&
                    SINIFSCOPE(rt_key(rt))->sin_scope_id != IFSCOPE_NONE) {
                        char scpstr[16];

                        snprintf(scpstr, sizeof(scpstr), "@%u",
                            SINIFSCOPE(rt_key(rt))->sin_scope_id);

                        strlcat(ds, scpstr, dslen);
                }
        }

        if (gs != NULL) {
                if (rt->rt_flags & RTF_GATEWAY) {
                        (void) inet_ntop(AF_INET,
                            &SIN(rt->rt_gateway)->sin_addr.s_addr, gs, gslen);
                } else if (rt->rt_ifp != NULL) {
                        snprintf(gs, gslen, "link#%u", rt->rt_ifp->if_unit);
                } else {
                        snprintf(gs, gslen, "%s", "link");
                }
        }
}

#if INET6
static void
rt_str6(struct rtentry *rt, char *ds, uint32_t dslen, char *gs, uint32_t gslen)
{
        VERIFY(rt_key(rt)->sa_family == AF_INET6);

        if (ds != NULL) {
                (void) inet_ntop(AF_INET6,
                    &SIN6(rt_key(rt))->sin6_addr, ds, dslen);
                if (dslen >= MAX_SCOPE_ADDR_STR_LEN &&
                    SIN6IFSCOPE(rt_key(rt))->sin6_scope_id != IFSCOPE_NONE) {
                        char scpstr[16];

                        snprintf(scpstr, sizeof(scpstr), "@%u",
                            SIN6IFSCOPE(rt_key(rt))->sin6_scope_id);

                        strlcat(ds, scpstr, dslen);
                }
        }

        if (gs != NULL) {
                if (rt->rt_flags & RTF_GATEWAY) {
                        (void) inet_ntop(AF_INET6,
                            &SIN6(rt->rt_gateway)->sin6_addr, gs, gslen);
                } else if (rt->rt_ifp != NULL) {
                        snprintf(gs, gslen, "link#%u", rt->rt_ifp->if_unit);
                } else {
                        snprintf(gs, gslen, "%s", "link");
                }
        }
}
#endif /* INET6 */


void
rt_str(struct rtentry *rt, char *ds, uint32_t dslen, char *gs, uint32_t gslen)
{
        switch (rt_key(rt)->sa_family) {
        case AF_INET:
                rt_str4(rt, ds, dslen, gs, gslen);
                break;
#if INET6
        case AF_INET6:
                rt_str6(rt, ds, dslen, gs, gslen);
                break;
#endif /* INET6 */
        default:
                if (ds != NULL)
                        bzero(ds, dslen);
                if (gs != NULL)
                        bzero(gs, gslen);
                break;
        }
}