xnu-6153.81.5.tar.gz

[apple/xnu.git] / bsd / netinet6 / in6_rmx.c

/*
 * Copyright (c) 2003-2016 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) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright 1994, 1995 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. 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.
 *
 */

/*
 * This code does two things necessary for the enhanced TCP metrics to
 * function in a useful manner:
 *  1) It marks all non-host routes as `cloning', thus ensuring that
 *     every actual reference to such a route actually gets turned
 *     into a reference to a host route to the specific destination
 *     requested.
 *  2) When such routes lose all their references, it arranges for them
 *     to be deleted in some random collection of circumstances, so that
 *     a large quantity of stale routing data is not kept in kernel memory
 *     indefinitely.  See in6_rtqtimo() below for the exact mechanism.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <kern/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/mbuf.h>
#include <sys/syslog.h>
#include <sys/mcache.h>
#include <kern/locks.h>

#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/ip_var.h>
#include <netinet/in_var.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>

#include <netinet/icmp6.h>

#include <netinet/tcp.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>

extern int      tvtohz(struct timeval *);

static int in6_rtqtimo_run;             /* in6_rtqtimo is scheduled to run */
static void in6_rtqtimo(void *);
static void in6_sched_rtqtimo(struct timeval *);

static struct radix_node *in6_addroute(void *, void *, struct radix_node_head *,
    struct radix_node *);
static struct radix_node *in6_deleteroute(void *, void *,
    struct radix_node_head *);
static struct radix_node *in6_matroute(void *, struct radix_node_head *);
static struct radix_node *in6_matroute_args(void *, struct radix_node_head *,
    rn_matchf_t *, void *);
static void in6_clsroute(struct radix_node *, struct radix_node_head *);
static int in6_rtqkill(struct radix_node *, void *);

/*
 * Accessed by in6_addroute(), in6_deleteroute() and in6_rtqkill(), during
 * which the routing lock (rnh_lock) is held and thus protects the variable.
 */
static int in6dynroutes;

/*
 * Do what we need to do when inserting a route.
 */
static struct radix_node *
in6_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
    struct radix_node *treenodes)
{
        struct rtentry *rt = (struct rtentry *)treenodes;
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)(void *)rt_key(rt);
        struct radix_node *ret;
        char dbuf[MAX_IPv6_STR_LEN], gbuf[MAX_IPv6_STR_LEN];
        uint32_t flags = rt->rt_flags;
        boolean_t verbose = (rt_verbose > 1);

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

        if (verbose) {
                rt_str(rt, dbuf, sizeof(dbuf), gbuf, sizeof(gbuf));
        }

        /*
         * If this is a dynamic route (which is created via Redirect) and
         * we already have the maximum acceptable number of such route entries,
         * reject creating a new one.  We could initiate garbage collection to
         * make available space right now, but the benefit would probably not
         * be worth the cleaning overhead; we only have to endure a slightly
         * suboptimal path even without the redirected route.
         */
        if ((rt->rt_flags & RTF_DYNAMIC) &&
            ip6_maxdynroutes >= 0 && in6dynroutes >= ip6_maxdynroutes) {
                return NULL;
        }

        /*
         * For IPv6, all unicast non-host routes are automatically cloning.
         */
        if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr)) {
                rt->rt_flags |= RTF_MULTICAST;
        }

        if (!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) {
                rt->rt_flags |= RTF_PRCLONING;
        }

        /*
         * A little bit of help for both IPv6 output and input:
         *   For local addresses, we make sure that RTF_LOCAL is set,
         *   with the thought that this might one day be used to speed up
         *   ip_input().
         *
         * We also mark routes to multicast addresses as such, because
         * it's easy to do and might be useful (but this is much more
         * dubious since it's so easy to inspect the address).  (This
         * is done above.)
         *
         * XXX
         * should elaborate the code.
         */
        if (rt->rt_flags & RTF_HOST) {
                IFA_LOCK_SPIN(rt->rt_ifa);
                if (IN6_ARE_ADDR_EQUAL(&satosin6(rt->rt_ifa->ifa_addr)->
                    sin6_addr, &sin6->sin6_addr)) {
                        rt->rt_flags |= RTF_LOCAL;
                }
                IFA_UNLOCK(rt->rt_ifa);
        }

        if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) &&
            rt->rt_ifp) {
                rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
        }

        ret = rn_addroute(v_arg, n_arg, head, treenodes);
        if (ret == NULL && (rt->rt_flags & RTF_HOST)) {
                struct rtentry *rt2;
                /*
                 * We are trying to add a host route, but can't.
                 * Find out if it is because of an
                 * ND6 entry and delete it if so.
                 */
                rt2 = rtalloc1_scoped_locked((struct sockaddr *)sin6, 0,
                    RTF_CLONING | RTF_PRCLONING, sin6_get_ifscope(rt_key(rt)));
                if (rt2 != NULL) {
                        char dbufc[MAX_IPv6_STR_LEN];

                        RT_LOCK(rt2);
                        if (verbose) {
                                rt_str(rt2, dbufc, sizeof(dbufc), NULL, 0);
                        }

                        if ((rt2->rt_flags & RTF_LLINFO) &&
                            (rt2->rt_flags & RTF_HOST) &&
                            rt2->rt_gateway != NULL &&
                            rt2->rt_gateway->sa_family == AF_LINK) {
                                if (verbose) {
                                        log(LOG_DEBUG, "%s: unable to insert "
                                            "route to %s:%s, flags=%b, due to "
                                            "existing ND6 route %s->%s "
                                            "flags=%b, attempting to delete\n",
                                            __func__, dbuf,
                                            (rt->rt_ifp != NULL) ?
                                            rt->rt_ifp->if_xname : "",
                                            rt->rt_flags, RTF_BITS,
                                            dbufc, (rt2->rt_ifp != NULL) ?
                                            rt2->rt_ifp->if_xname : "",
                                            rt2->rt_flags, RTF_BITS);
                                }
                                /*
                                 * 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(rt2);
                                (void) rtrequest_locked(RTM_DELETE, rt_key(rt2),
                                    rt2->rt_gateway, rt_mask(rt2),
                                    rt2->rt_flags, NULL);
                                ret = rn_addroute(v_arg, n_arg, head,
                                    treenodes);
                        } else {
                                RT_UNLOCK(rt2);
                        }
                        rtfree_locked(rt2);
                }
        } else if (ret == NULL && (rt->rt_flags & RTF_CLONING)) {
                struct rtentry *rt2;
                /*
                 * We are trying to add a net route, but can't.
                 * The following case should be allowed, so we'll make a
                 * special check for this:
                 *      Two IPv6 addresses with the same prefix is assigned
                 *      to a single interrface.
                 *      # ifconfig if0 inet6 3ffe:0501::1 prefix 64 alias (*1)
                 *      # ifconfig if0 inet6 3ffe:0501::2 prefix 64 alias (*2)
                 *      In this case, (*1) and (*2) want to add the same
                 *      net route entry, 3ffe:0501:: -> if0.
                 *      This case should not raise an error.
                 */
                rt2 = rtalloc1_scoped_locked((struct sockaddr *)sin6, 0,
                    RTF_CLONING | RTF_PRCLONING, sin6_get_ifscope(rt_key(rt)));
                if (rt2 != NULL) {
                        RT_LOCK(rt2);
                        if ((rt2->rt_flags & (RTF_CLONING | RTF_HOST |
                            RTF_GATEWAY)) == RTF_CLONING &&
                            rt2->rt_gateway &&
                            rt2->rt_gateway->sa_family == AF_LINK &&
                            rt2->rt_ifp == rt->rt_ifp) {
                                ret = rt2->rt_nodes;
                        }
                        RT_UNLOCK(rt2);
                        rtfree_locked(rt2);
                }
        }

        if (ret != NULL && (rt->rt_flags & RTF_DYNAMIC)) {
                in6dynroutes++;
        }

        if (!verbose) {
                goto done;
        }

        if (ret != NULL) {
                if (flags != rt->rt_flags) {
                        log(LOG_DEBUG, "%s: route to %s->%s->%s inserted, "
                            "oflags=%b, flags=%b\n", __func__,
                            dbuf, gbuf, (rt->rt_ifp != NULL) ?
                            rt->rt_ifp->if_xname : "", flags, RTF_BITS,
                            rt->rt_flags, RTF_BITS);
                } else {
                        log(LOG_DEBUG, "%s: route to %s->%s->%s inserted, "
                            "flags=%b\n", __func__, dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            rt->rt_flags, RTF_BITS);
                }
        } else {
                log(LOG_DEBUG, "%s: unable to insert route to %s->%s->%s, "
                    "flags=%b, already exists\n", __func__, dbuf, gbuf,
                    (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                    rt->rt_flags, RTF_BITS);
        }
done:
        return ret;
}

static struct radix_node *
in6_deleteroute(void *v_arg, void *netmask_arg, struct radix_node_head *head)
{
        struct radix_node *rn;

        LCK_MTX_ASSERT(rnh_lock, LCK_MTX_ASSERT_OWNED);

        rn = rn_delete(v_arg, netmask_arg, head);
        if (rn != NULL) {
                struct rtentry *rt = (struct rtentry *)rn;

                RT_LOCK(rt);
                if (rt->rt_flags & RTF_DYNAMIC) {
                        in6dynroutes--;
                }
                if (rt_verbose > 1) {
                        char dbuf[MAX_IPv6_STR_LEN], gbuf[MAX_IPv6_STR_LEN];

                        rt_str(rt, dbuf, sizeof(dbuf), gbuf, sizeof(gbuf));
                        log(LOG_DEBUG, "%s: route to %s->%s->%s deleted, "
                            "flags=%b\n", __func__, dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            rt->rt_flags, RTF_BITS);
                }
                RT_UNLOCK(rt);
        }
        return rn;
}

/*
 * Validate (unexpire) an expiring AF_INET6 route.
 */
struct radix_node *
in6_validate(struct radix_node *rn)
{
        struct rtentry *rt = (struct rtentry *)rn;

        RT_LOCK_ASSERT_HELD(rt);

        /* This is first reference? */
        if (rt->rt_refcnt == 0) {
                if (rt_verbose > 2) {
                        char dbuf[MAX_IPv6_STR_LEN], gbuf[MAX_IPv6_STR_LEN];

                        rt_str(rt, dbuf, sizeof(dbuf), gbuf, sizeof(gbuf));
                        log(LOG_DEBUG, "%s: route to %s->%s->%s validated, "
                            "flags=%b\n", __func__, dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            rt->rt_flags, RTF_BITS);
                }

                /*
                 * It's one of ours; unexpire it.  If the timer is already
                 * scheduled, let it run later as it won't re-arm itself
                 * if there's nothing to do.
                 */
                if (rt->rt_flags & RTPRF_OURS) {
                        rt->rt_flags &= ~RTPRF_OURS;
                        rt_setexpire(rt, 0);
                }
        }
        return rn;
}

/*
 * Similar to in6_matroute_args except without the leaf-matching parameters.
 */
static struct radix_node *
in6_matroute(void *v_arg, struct radix_node_head *head)
{
        return in6_matroute_args(v_arg, head, NULL, NULL);
}

/*
 * This code is the inverse of in6_clsroute: on first reference, if we
 * were managing the route, stop doing so and set the expiration timer
 * back off again.
 */
static struct radix_node *
in6_matroute_args(void *v_arg, struct radix_node_head *head,
    rn_matchf_t *f, void *w)
{
        struct radix_node *rn = rn_match_args(v_arg, head, f, w);

        if (rn != NULL) {
                RT_LOCK_SPIN((struct rtentry *)rn);
                in6_validate(rn);
                RT_UNLOCK((struct rtentry *)rn);
        }
        return rn;
}

SYSCTL_DECL(_net_inet6_ip6);

/* one hour is ``really old'' */
static uint32_t rtq_reallyold = 60 * 60;
SYSCTL_UINT(_net_inet6_ip6, IPV6CTL_RTEXPIRE, rtexpire,
    CTLFLAG_RW | CTLFLAG_LOCKED, &rtq_reallyold, 0, "");

/* never automatically crank down to less */
static uint32_t rtq_minreallyold = 10;
SYSCTL_UINT(_net_inet6_ip6, IPV6CTL_RTMINEXPIRE, rtminexpire,
    CTLFLAG_RW | CTLFLAG_LOCKED, &rtq_minreallyold, 0, "");

/* 128 cached routes is ``too many'' */
static uint32_t rtq_toomany = 128;
SYSCTL_UINT(_net_inet6_ip6, IPV6CTL_RTMAXCACHE, rtmaxcache,
    CTLFLAG_RW | CTLFLAG_LOCKED, &rtq_toomany, 0, "");

/*
 * On last reference drop, mark the route as belong to us so that it can be
 * timed out.
 */
static void
in6_clsroute(struct radix_node *rn, struct radix_node_head *head)
{
#pragma unused(head)
        char dbuf[MAX_IPv6_STR_LEN], gbuf[MAX_IPv6_STR_LEN];
        struct rtentry *rt = (struct rtentry *)rn;
        boolean_t verbose = (rt_verbose > 1);

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

        if (!(rt->rt_flags & RTF_UP)) {
                return;         /* prophylactic measures */
        }
        if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST) {
                return;
        }

        if (rt->rt_flags & RTPRF_OURS) {
                return;
        }

        if (!(rt->rt_flags & (RTF_WASCLONED | RTF_DYNAMIC))) {
                return;
        }

        if (verbose) {
                rt_str(rt, dbuf, sizeof(dbuf), gbuf, sizeof(gbuf));
        }

        /*
         * Delete the route immediately if RTF_DELCLONE is set or
         * if route caching is disabled (rtq_reallyold set to 0).
         * Otherwise, let it expire and be deleted by in6_rtqkill().
         */
        if ((rt->rt_flags & RTF_DELCLONE) || rtq_reallyold == 0) {
                int err;

                if (verbose) {
                        log(LOG_DEBUG, "%s: deleting route to %s->%s->%s, "
                            "flags=%b\n", __func__, dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            rt->rt_flags, RTF_BITS);
                }
                /*
                 * Delete the route from the radix tree but since we are
                 * called when the route's reference count is 0, don't
                 * deallocate it until we return from this routine by
                 * telling rtrequest that we're interested in it.
                 * 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);
                err = rtrequest_locked(RTM_DELETE, rt_key(rt),
                    rt->rt_gateway, rt_mask(rt), rt->rt_flags, &rt);
                if (err == 0) {
                        /* Now let the caller free it */
                        RT_LOCK(rt);
                        RT_REMREF_LOCKED(rt);
                } else {
                        RT_LOCK(rt);
                        if (!verbose) {
                                rt_str(rt, dbuf, sizeof(dbuf),
                                    gbuf, sizeof(gbuf));
                        }
                        log(LOG_ERR, "%s: error deleting route to "
                            "%s->%s->%s, flags=%b, err=%d\n", __func__,
                            dbuf, gbuf, (rt->rt_ifp != NULL) ?
                            rt->rt_ifp->if_xname : "", rt->rt_flags,
                            RTF_BITS, err);
                }
        } else {
                uint64_t timenow;

                timenow = net_uptime();
                rt->rt_flags |= RTPRF_OURS;
                rt_setexpire(rt, timenow + rtq_reallyold);

                if (verbose) {
                        log(LOG_DEBUG, "%s: route to %s->%s->%s invalidated, "
                            "flags=%b, expire=T+%u\n", __func__, dbuf, gbuf,
                            (rt->rt_ifp != NULL) ? rt->rt_ifp->if_xname : "",
                            rt->rt_flags, RTF_BITS, rt->rt_expire - timenow);
                }

                /* We have at least one entry; arm the timer if not already */
                in6_sched_rtqtimo(NULL);
        }
}

struct rtqk_arg {
        struct radix_node_head *rnh;
        int updating;
        int draining;
        uint32_t killed;
        uint32_t found;
        uint64_t nextstop;
};

/*
 * Get rid of old routes.  When draining, this deletes everything, even when
 * the timeout is not expired yet.  This also applies if the route is dynamic
 * and there are sufficiently large number of such routes (more than a half of
 * maximum).  When updating, this makes sure that nothing has a timeout longer
 * than the current value of rtq_reallyold.
 */
static int
in6_rtqkill(struct radix_node *rn, void *rock)
{
        struct rtqk_arg *ap = rock;
        struct rtentry *rt = (struct rtentry *)rn;
        boolean_t verbose = (rt_verbose > 1);
        uint64_t timenow;
        int err;

        timenow = net_uptime();
        LCK_MTX_ASSERT(rnh_lock, LCK_MTX_ASSERT_OWNED);

        RT_LOCK(rt);
        if (rt->rt_flags & RTPRF_OURS) {
                char dbuf[MAX_IPv6_STR_LEN], gbuf[MAX_IPv6_STR_LEN];

                if (verbose) {
                        rt_str(rt, dbuf, sizeof(dbuf), gbuf, sizeof(gbuf));
                }

                ap->found++;
                VERIFY(rt->rt_expire == 0 || rt->rt_rmx.rmx_expire != 0);
                VERIFY(rt->rt_expire != 0 || rt->rt_rmx.rmx_expire == 0);
                if (ap->draining || rt->rt_expire <= timenow ||
                    ((rt->rt_flags & RTF_DYNAMIC) && ip6_maxdynroutes >= 0 &&
                    in6dynroutes > ip6_maxdynroutes / 2)) {
                        if (rt->rt_refcnt > 0) {
                                panic("%s: route %p marked with RTPRF_OURS "
                                    "with non-zero refcnt (%u)", __func__,
                                    rt, rt->rt_refcnt);
                                /* NOTREACHED */
                        }

                        if (verbose) {
                                log(LOG_DEBUG, "%s: deleting route to "
                                    "%s->%s->%s, flags=%b, draining=%d\n",
                                    __func__, dbuf, gbuf, (rt->rt_ifp != NULL) ?
                                    rt->rt_ifp->if_xname : "", rt->rt_flags,
                                    RTF_BITS, ap->draining);
                        }
                        RT_ADDREF_LOCKED(rt);   /* for us to free below */
                        /*
                         * Delete this route since we're done with it;
                         * the route may be freed afterwards, so we
                         * can no longer refer to 'rt' upon returning
                         * from rtrequest().  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);
                        err = rtrequest_locked(RTM_DELETE, rt_key(rt),
                            rt->rt_gateway, rt_mask(rt), rt->rt_flags, NULL);
                        if (err != 0) {
                                RT_LOCK(rt);
                                if (!verbose) {
                                        rt_str(rt, dbuf, sizeof(dbuf),
                                            gbuf, sizeof(gbuf));
                                }
                                log(LOG_ERR, "%s: error deleting route to "
                                    "%s->%s->%s, flags=%b, err=%d\n", __func__,
                                    dbuf, gbuf, (rt->rt_ifp != NULL) ?
                                    rt->rt_ifp->if_xname : "", rt->rt_flags,
                                    RTF_BITS, err);
                                RT_UNLOCK(rt);
                        } else {
                                ap->killed++;
                        }
                        rtfree_locked(rt);
                } else {
                        uint64_t expire = (rt->rt_expire - timenow);

                        if (ap->updating && expire > rtq_reallyold) {
                                rt_setexpire(rt, timenow + rtq_reallyold);
                                if (verbose) {
                                        log(LOG_DEBUG, "%s: route to "
                                            "%s->%s->%s, flags=%b, adjusted "
                                            "expire=T+%u (was T+%u)\n",
                                            __func__, dbuf, gbuf,
                                            (rt->rt_ifp != NULL) ?
                                            rt->rt_ifp->if_xname : "",
                                            rt->rt_flags, RTF_BITS,
                                            (rt->rt_expire - timenow), expire);
                                }
                        }
                        ap->nextstop = lmin(ap->nextstop, rt->rt_expire);
                        RT_UNLOCK(rt);
                }
        } else {
                RT_UNLOCK(rt);
        }

        return 0;
}

#define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
static int rtq_timeout = RTQ_TIMEOUT;

static void
in6_rtqtimo(void *targ)
{
#pragma unused(targ)
        struct radix_node_head *rnh;
        struct rtqk_arg arg;
        struct timeval atv;
        static uint64_t last_adjusted_timeout = 0;
        boolean_t verbose = (rt_verbose > 1);
        uint64_t timenow;
        uint32_t ours;

        lck_mtx_lock(rnh_lock);
        rnh = rt_tables[AF_INET6];
        VERIFY(rnh != NULL);

        /* Get the timestamp after we acquire the lock for better accuracy */
        timenow = net_uptime();
        if (verbose) {
                log(LOG_DEBUG, "%s: initial nextstop is T+%u seconds\n",
                    __func__, rtq_timeout);
        }
        bzero(&arg, sizeof(arg));
        arg.rnh = rnh;
        arg.nextstop = timenow + rtq_timeout;
        rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
        if (verbose) {
                log(LOG_DEBUG, "%s: found %u, killed %u\n", __func__,
                    arg.found, arg.killed);
        }
        /*
         * Attempt to be somewhat dynamic about this:
         * If there are ``too many'' routes sitting around taking up space,
         * then crank down the timeout, and see if we can't make some more
         * go away.  However, we make sure that we will never adjust more
         * than once in rtq_timeout seconds, to keep from cranking down too
         * hard.
         */
        ours = (arg.found - arg.killed);
        if (ours > rtq_toomany &&
            ((timenow - last_adjusted_timeout) >= (uint64_t)rtq_timeout) &&
            rtq_reallyold > rtq_minreallyold) {
                rtq_reallyold = 2 * rtq_reallyold / 3;
                if (rtq_reallyold < rtq_minreallyold) {
                        rtq_reallyold = rtq_minreallyold;
                }

                last_adjusted_timeout = timenow;
                if (verbose) {
                        log(LOG_DEBUG, "%s: adjusted rtq_reallyold to %d "
                            "seconds\n", __func__, rtq_reallyold);
                }
                arg.found = arg.killed = 0;
                arg.updating = 1;
                rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
        }

        atv.tv_usec = 0;
        atv.tv_sec = arg.nextstop - timenow;
        /* re-arm the timer only if there's work to do */
        in6_rtqtimo_run = 0;
        if (ours > 0) {
                in6_sched_rtqtimo(&atv);
        } else if (verbose) {
                log(LOG_DEBUG, "%s: not rescheduling timer\n", __func__);
        }
        lck_mtx_unlock(rnh_lock);
}

static void
in6_sched_rtqtimo(struct timeval *atv)
{
        LCK_MTX_ASSERT(rnh_lock, LCK_MTX_ASSERT_OWNED);

        if (!in6_rtqtimo_run) {
                struct timeval tv;

                if (atv == NULL) {
                        tv.tv_usec = 0;
                        tv.tv_sec = MAX(rtq_timeout / 10, 1);
                        atv = &tv;
                }
                if (rt_verbose > 1) {
                        log(LOG_DEBUG, "%s: timer scheduled in "
                            "T+%llus.%lluu\n", __func__,
                            (uint64_t)atv->tv_sec, (uint64_t)atv->tv_usec);
                }
                in6_rtqtimo_run = 1;
                timeout(in6_rtqtimo, NULL, tvtohz(atv));
        }
}

void
in6_rtqdrain(void)
{
        struct radix_node_head *rnh;
        struct rtqk_arg arg;

        if (rt_verbose > 1) {
                log(LOG_DEBUG, "%s: draining routes\n", __func__);
        }

        lck_mtx_lock(rnh_lock);
        rnh = rt_tables[AF_INET6];
        VERIFY(rnh != NULL);
        bzero(&arg, sizeof(arg));
        arg.rnh = rnh;
        arg.draining = 1;
        rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
        lck_mtx_unlock(rnh_lock);
}

/*
 * Initialize our routing tree.
 */
int
in6_inithead(void **head, int off)
{
        struct radix_node_head *rnh;

        /* If called from route_init(), make sure it is exactly once */
        VERIFY(head != (void **)&rt_tables[AF_INET6] || *head == NULL);

        if (!rn_inithead(head, off)) {
                return 0;
        }

        /*
         * We can get here from nfs_subs.c as well, in which case this
         * won't be for the real routing table and thus we're done;
         * this also takes care of the case when we're called more than
         * once from anywhere but route_init().
         */
        if (head != (void **)&rt_tables[AF_INET6]) {
                return 1;     /* only do this for the real routing table */
        }
        rnh = *head;
        rnh->rnh_addaddr = in6_addroute;
        rnh->rnh_deladdr = in6_deleteroute;
        rnh->rnh_matchaddr = in6_matroute;
        rnh->rnh_matchaddr_args = in6_matroute_args;
        rnh->rnh_close = in6_clsroute;
        return 1;
}