Merge commit 'ea01a15a654b9e1c7b37d958f4d1911882ed7781'

[unleashed.git] / kernel / net / ip / ip_ire.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 1990 Mentat Inc.
 */

/*
 * This file contains routines that manipulate Internet Routing Entries (IREs).
 */

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/strsun.h>
#include <sys/strsubr.h>
#include <sys/ddi.h>
#include <sys/cmn_err.h>
#include <sys/policy.h>

#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <net/if_dl.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>

#include <inet/common.h>
#include <inet/mi.h>
#include <inet/ip.h>
#include <inet/ip6.h>
#include <inet/ip_ndp.h>
#include <inet/arp.h>
#include <inet/ip_if.h>
#include <inet/ip_ire.h>
#include <inet/ip_ftable.h>
#include <inet/ip_rts.h>
#include <inet/nd.h>
#include <inet/tunables.h>

#include <inet/tcp.h>
#include <inet/ipclassifier.h>
#include <sys/zone.h>
#include <sys/cpuvar.h>

struct kmem_cache *rt_entry_cache;

typedef struct nce_clookup_s {
        ipaddr_t ncecl_addr;
        boolean_t ncecl_found;
} nce_clookup_t;

/*
 * Synchronization notes:
 *
 * The fields of the ire_t struct are protected in the following way :
 *
 * ire_next/ire_ptpn
 *
 *      - bucket lock of the forwarding table in which is ire stored.
 *
 * ire_ill, ire_u *except* ire_gateway_addr[v6], ire_mask,
 * ire_type, ire_create_time, ire_masklen, ire_ipversion, ire_flags,
 * ire_bucket
 *
 *      - Set in ire_create_v4/v6 and never changes after that. Thus,
 *        we don't need a lock whenever these fields are accessed.
 *
 *      - ire_bucket and ire_masklen (also set in ire_create) is set in
 *        ire_add before inserting in the bucket and never
 *        changes after that. Thus we don't need a lock whenever these
 *        fields are accessed.
 *
 * ire_gateway_addr_v4[v6]
 *
 *      - ire_gateway_addr_v4[v6] is set during ire_create and later modified
 *        by rts_setgwr[v6]. As ire_gateway_addr is a uint32_t, updates to
 *        it assumed to be atomic and hence the other parts of the code
 *        does not use any locks. ire_gateway_addr_v6 updates are not atomic
 *        and hence any access to it uses ire_lock to get/set the right value.
 *
 * ire_refcnt, ire_identical_ref
 *
 *      - Updated atomically using atomic_add_32
 *
 * ire_ssthresh, ire_rtt_sd, ire_rtt, ire_ib_pkt_count, ire_ob_pkt_count
 *
 *      - Assumes that 32 bit writes are atomic. No locks. ire_lock is
 *        used to serialize updates to ire_ssthresh, ire_rtt_sd, ire_rtt.
 *
 * ire_generation
 *      - Under ire_lock
 *
 * ire_nce_cache
 *      - Under ire_lock
 *
 * ire_dep_parent (To next IRE in recursive lookup chain)
 *      - Under ips_ire_dep_lock. Write held when modifying. Read held when
 *        walking. We also hold ire_lock when modifying to allow the data path
 *        to only acquire ire_lock.
 *
 * ire_dep_parent_generation (Generation number from ire_dep_parent)
 *      - Under ips_ire_dep_lock and/or ire_lock. (A read claim on the dep_lock
 *        and ire_lock held when modifying)
 *
 * ire_dep_children (From parent to first child)
 * ire_dep_sib_next (linked list of siblings)
 * ire_dep_sib_ptpn (linked list of siblings)
 *      - Under ips_ire_dep_lock. Write held when modifying. Read held when
 *        walking.
 *
 * As we always hold the bucket locks in all the places while accessing
 * the above values, it is natural to use them for protecting them.
 *
 * We have a forwarding table for IPv4 and IPv6. The IPv6 forwarding table
 * (ip_forwarding_table_v6) is an array of pointers to arrays of irb_t
 * structures. ip_forwarding_table_v6 is allocated dynamically in
 * ire_add_v6. ire_ft_init_lock is used to serialize multiple threads
 * initializing the same bucket. Once a bucket is initialized, it is never
 * de-alloacted. This assumption enables us to access
 * ip_forwarding_table_v6[i] without any locks.
 *
 * The forwarding table for IPv4 is a radix tree whose leaves
 * are rt_entry structures containing the irb_t for the rt_dst. The irb_t
 * for IPv4 is dynamically allocated and freed.
 *
 * Each irb_t - ire bucket structure has a lock to protect
 * a bucket and the ires residing in the bucket have a back pointer to
 * the bucket structure. It also has a reference count for the number
 * of threads walking the bucket - irb_refcnt which is bumped up
 * using the irb_refhold function. The flags irb_marks can be
 * set to IRB_MARK_CONDEMNED indicating that there are some ires
 * in this bucket that are IRE_IS_CONDEMNED and the
 * last thread to leave the bucket should delete the ires. Usually
 * this is done by the irb_refrele function which is used to decrement
 * the reference count on a bucket. See comments above irb_t structure
 * definition in ip.h for further details.
 *
 * The ire_refhold/ire_refrele functions operate on the ire which increments/
 * decrements the reference count, ire_refcnt, atomically on the ire.
 * ire_refcnt is modified only using those functions. Operations on the IRE
 * could be described as follows :
 *
 * CREATE an ire with reference count initialized to 1.
 *
 * ADDITION of an ire holds the bucket lock, checks for duplicates
 * and then adds the ire. ire_add returns the ire after
 * bumping up once more i.e the reference count is 2. This is to avoid
 * an extra lookup in the functions calling ire_add which wants to
 * work with the ire after adding.
 *
 * LOOKUP of an ire bumps up the reference count using ire_refhold
 * function. It is valid to bump up the referece count of the IRE,
 * after the lookup has returned an ire. Following are the lookup
 * functions that return an HELD ire :
 *
 * ire_ftable_lookup[_v6], ire_lookup_multi_ill[_v6]
 *
 * DELETION of an ire holds the bucket lock, removes it from the list
 * and then decrements the reference count for having removed from the list
 * by using the ire_refrele function. If some other thread has looked up
 * the ire, the reference count would have been bumped up and hence
 * this ire will not be freed once deleted. It will be freed once the
 * reference count drops to zero.
 *
 * Add and Delete acquires the bucket lock as RW_WRITER, while all the
 * lookups acquire the bucket lock as RW_READER.
 *
 * The general rule is to do the ire_refrele in the function
 * that is passing the ire as an argument.
 *
 * In trying to locate ires the following points are to be noted.
 *
 * IRE_IS_CONDEMNED signifies that the ire has been logically deleted and is
 * to be ignored when walking the ires using ire_next.
 *
 * Zones note:
 *      Walking IREs within a given zone also walks certain ires in other
 *      zones.  This is done intentionally.  IRE walks with a specified
 *      zoneid are used only when doing informational reports, and
 *      zone users want to see things that they can access. See block
 *      comment in ire_walk_ill_match().
 */

/*
 * The size of the forwarding table.  We will make sure that it is a
 * power of 2 in ip_ire_init().
 * Setable in /etc/system
 */
uint32_t ip6_ftable_hash_size = IP6_FTABLE_HASH_SIZE;

struct  kmem_cache      *ire_cache;
struct  kmem_cache      *ncec_cache;
struct  kmem_cache      *nce_cache;

static ire_t    ire_null;

static ire_t    *ire_add_v4(ire_t *ire);
static void     ire_delete_v4(ire_t *ire);
static void     ire_dep_invalidate_children(ire_t *child);
static void     ire_walk_ipvers(pfv_t func, void *arg, uchar_t vers,
    zoneid_t zoneid, ip_stack_t *);
static void     ire_walk_ill_ipvers(uint_t match_flags, uint_t ire_type,
    pfv_t func, void *arg, uchar_t vers, ill_t *ill);
#ifdef DEBUG
static void     ire_trace_cleanup(const ire_t *);
#endif
static void     ire_dep_incr_generation_locked(ire_t *);

/*
 * Following are the functions to increment/decrement the reference
 * count of the IREs and IRBs (ire bucket).
 *
 * 1) We bump up the reference count of an IRE to make sure that
 *    it does not get deleted and freed while we are using it.
 *    Typically all the lookup functions hold the bucket lock,
 *    and look for the IRE. If it finds an IRE, it bumps up the
 *    reference count before dropping the lock. Sometimes we *may* want
 *    to bump up the reference count after we *looked* up i.e without
 *    holding the bucket lock. So, the ire_refhold function does not assert
 *    on the bucket lock being held. Any thread trying to delete from
 *    the hash bucket can still do so but cannot free the IRE if
 *    ire_refcnt is not 0.
 *
 * 2) We bump up the reference count on the bucket where the IRE resides
 *    (IRB), when we want to prevent the IREs getting deleted from a given
 *    hash bucket. This makes life easier for ire_walk type functions which
 *    wants to walk the IRE list, call a function, but needs to drop
 *    the bucket lock to prevent recursive rw_enters. While the
 *    lock is dropped, the list could be changed by other threads or
 *    the same thread could end up deleting the ire or the ire pointed by
 *    ire_next. ire_refholding the ire or ire_next is not sufficient as
 *    a delete will still remove the ire from the bucket while we have
 *    dropped the lock and hence the ire_next would be NULL. Thus, we
 *    need a mechanism to prevent deletions from a given bucket.
 *
 *    To prevent deletions, we bump up the reference count on the
 *    bucket. If the bucket is held, ire_delete just marks both
 *    the ire and irb as CONDEMNED. When the
 *    reference count on the bucket drops to zero, all the CONDEMNED ires
 *    are deleted. We don't have to bump up the reference count on the
 *    bucket if we are walking the bucket and never have to drop the bucket
 *    lock. Note that irb_refhold does not prevent addition of new ires
 *    in the list. It is okay because addition of new ires will not cause
 *    ire_next to point to freed memory. We do irb_refhold only when
 *    all of the 3 conditions are true :
 *
 *    1) The code needs to walk the IRE bucket from start to end.
 *    2) It may have to drop the bucket lock sometimes while doing (1)
 *    3) It does not want any ires to be deleted meanwhile.
 */

/*
 * Bump up the reference count on the hash bucket - IRB to
 * prevent ires from being deleted in this bucket.
 */
void
irb_refhold(irb_t *irb)
{
        rw_enter(&irb->irb_lock, RW_WRITER);
        irb->irb_refcnt++;
        ASSERT(irb->irb_refcnt != 0);
        rw_exit(&irb->irb_lock);
}

void
irb_refhold_locked(irb_t *irb)
{
        ASSERT(RW_WRITE_HELD(&irb->irb_lock));
        irb->irb_refcnt++;
        ASSERT(irb->irb_refcnt != 0);
}

/*
 * Note: when IRB_MARK_DYNAMIC is not set the irb_t
 * is statically allocated, so that when the irb_refcnt goes to 0,
 * we simply clean up the ire list and continue.
 */
void
irb_refrele(irb_t *irb)
{
        if (irb->irb_marks & IRB_MARK_DYNAMIC) {
                irb_refrele_ftable(irb);
        } else {
                rw_enter(&irb->irb_lock, RW_WRITER);
                ASSERT(irb->irb_refcnt != 0);
                if (--irb->irb_refcnt   == 0 &&
                    (irb->irb_marks & IRB_MARK_CONDEMNED)) {
                        ire_t *ire_list;

                        ire_list = ire_unlink(irb);
                        rw_exit(&irb->irb_lock);
                        ASSERT(ire_list != NULL);
                        ire_cleanup(ire_list);
                } else {
                        rw_exit(&irb->irb_lock);
                }
        }
}


/*
 * Bump up the reference count on the IRE. We cannot assert that the
 * bucket lock is being held as it is legal to bump up the reference
 * count after the first lookup has returned the IRE without
 * holding the lock.
 */
void
ire_refhold(ire_t *ire)
{
        atomic_inc_32(&(ire)->ire_refcnt);
        ASSERT((ire)->ire_refcnt != 0);
#ifdef DEBUG
        ire_trace_ref(ire);
#endif
}

void
ire_refhold_notr(ire_t *ire)
{
        atomic_inc_32(&(ire)->ire_refcnt);
        ASSERT((ire)->ire_refcnt != 0);
}

void
ire_refhold_locked(ire_t *ire)
{
#ifdef DEBUG
        ire_trace_ref(ire);
#endif
        ire->ire_refcnt++;
}

/*
 * Release a ref on an IRE.
 *
 * Must not be called while holding any locks. Otherwise if this is
 * the last reference to be released there is a chance of recursive mutex
 * panic due to ire_refrele -> ipif_ill_refrele_tail -> qwriter_ip trying
 * to restart an ioctl. The one exception is when the caller is sure that
 * this is not the last reference to be released. Eg. if the caller is
 * sure that the ire has not been deleted and won't be deleted.
 *
 * In architectures e.g sun4u, where atomic_add_32_nv is just
 * a cas, we need to maintain the right memory barrier semantics
 * as that of mutex_exit i.e all the loads and stores should complete
 * before the cas is executed. membar_exit() does that here.
 */
void
ire_refrele(ire_t *ire)
{
#ifdef DEBUG
        ire_untrace_ref(ire);
#endif
        ASSERT((ire)->ire_refcnt != 0);
        membar_exit();
        if (atomic_dec_32_nv(&(ire)->ire_refcnt) == 0)
                ire_inactive(ire);
}

void
ire_refrele_notr(ire_t *ire)
{
        ASSERT((ire)->ire_refcnt != 0);
        membar_exit();
        if (atomic_dec_32_nv(&(ire)->ire_refcnt) == 0)
                ire_inactive(ire);
}

/*
 * This function is associated with the IP_IOC_IRE_DELETE[_NO_REPLY]
 * IOCTL[s].  The NO_REPLY form is used by TCP to tell IP that it is
 * having problems reaching a particular destination.
 * This will make IP consider alternate routes (e.g., when there are
 * muliple default routes), and it will also make IP discard any (potentially)
 * stale redirect.
 * Management processes may want to use the version that generates a reply.
 *
 * With the use of NUD like behavior for IPv4/ARP in addition to IPv6
 * this function shouldn't be necessary for IP to recover from a bad redirect,
 * a bad default router (when there are multiple default routers), or
 * a stale ND/ARP entry. But we retain it in any case.
 * For instance, this is helpful when TCP suspects a failure before NUD does.
 */
int
ip_ire_delete(queue_t *q, mblk_t *mp, cred_t *ioc_cr)
{
        uchar_t         *addr_ucp;
        uint_t          ipversion;
        sin_t           *sin;
        sin6_t          *sin6;
        ipaddr_t        v4addr;
        in6_addr_t      v6addr;
        ire_t           *ire;
        ipid_t          *ipid;
        zoneid_t        zoneid;
        ip_stack_t      *ipst;

        ASSERT(q->q_next == NULL);
        zoneid = IPCL_ZONEID(Q_TO_CONN(q));
        ipst = CONNQ_TO_IPST(q);

        /*
         * Check privilege using the ioctl credential; if it is NULL
         * then this is a kernel message and therefor privileged.
         */
        if (ioc_cr != NULL && secpolicy_ip_config(ioc_cr, B_FALSE) != 0)
                return (EPERM);

        ipid = (ipid_t *)mp->b_rptr;

        addr_ucp = mi_offset_param(mp, ipid->ipid_addr_offset,
            ipid->ipid_addr_length);
        if (addr_ucp == NULL || !OK_32PTR(addr_ucp))
                return (EINVAL);
        switch (ipid->ipid_addr_length) {
        case sizeof (sin_t):
                /*
                 * got complete (sockaddr) address - increment addr_ucp to point
                 * at the ip_addr field.
                 */
                sin = (sin_t *)addr_ucp;
                addr_ucp = (uchar_t *)&sin->sin_addr.s_addr;
                ipversion = IPV4_VERSION;
                break;
        case sizeof (sin6_t):
                /*
                 * got complete (sockaddr) address - increment addr_ucp to point
                 * at the ip_addr field.
                 */
                sin6 = (sin6_t *)addr_ucp;
                addr_ucp = (uchar_t *)&sin6->sin6_addr;
                ipversion = IPV6_VERSION;
                break;
        default:
                return (EINVAL);
        }
        if (ipversion == IPV4_VERSION) {
                /* Extract the destination address. */
                bcopy(addr_ucp, &v4addr, IP_ADDR_LEN);

                ire = ire_ftable_lookup_v4(v4addr, 0, 0, 0, NULL,
                    zoneid, MATCH_IRE_DSTONLY, 0, ipst, NULL);
        } else {
                /* Extract the destination address. */
                bcopy(addr_ucp, &v6addr, IPV6_ADDR_LEN);

                ire = ire_ftable_lookup_v6(&v6addr, NULL, NULL, 0, NULL,
                    zoneid, MATCH_IRE_DSTONLY, 0, ipst, NULL);
        }
        if (ire != NULL) {
                if (ipversion == IPV4_VERSION) {
                        ip_rts_change(RTM_LOSING, ire->ire_addr,
                            ire->ire_gateway_addr, ire->ire_mask,
                            (Q_TO_CONN(q))->conn_laddr_v4,  0, 0, 0,
                            (RTA_DST | RTA_GATEWAY | RTA_NETMASK | RTA_IFA),
                            ire->ire_ipst);
                }
                (void) ire_no_good(ire);
                ire_refrele(ire);
        }
        return (0);
}

/*
 * Initialize the ire that is specific to IPv4 part and call
 * ire_init_common to finish it.
 * Returns zero or errno.
 */
int
ire_init_v4(ire_t *ire, uchar_t *addr, uchar_t *mask, uchar_t *gateway,
    ushort_t type, ill_t *ill, zoneid_t zoneid, uint_t flags,
    ip_stack_t *ipst)
{
        int error;

        BUMP_IRE_STATS(ipst->ips_ire_stats_v4, ire_stats_alloced);

        if (addr != NULL)
                bcopy(addr, &ire->ire_addr, IP_ADDR_LEN);
        if (gateway != NULL)
                bcopy(gateway, &ire->ire_gateway_addr, IP_ADDR_LEN);

        /* Make sure we don't have stray values in some fields */
        switch (type) {
        case IRE_LOOPBACK:
        case IRE_HOST:
        case IRE_BROADCAST:
        case IRE_LOCAL:
        case IRE_IF_CLONE:
                ire->ire_mask = IP_HOST_MASK;
                ire->ire_masklen = IPV4_ABITS;
                break;
        case IRE_PREFIX:
        case IRE_DEFAULT:
        case IRE_IF_RESOLVER:
        case IRE_IF_NORESOLVER:
                if (mask != NULL) {
                        bcopy(mask, &ire->ire_mask, IP_ADDR_LEN);
                        ire->ire_masklen = ip_mask_to_plen(ire->ire_mask);
                }
                break;
        case IRE_MULTICAST:
        case IRE_NOROUTE:
                ASSERT(mask == NULL);
                break;
        default:
                ASSERT(0);
                return (EINVAL);
        }

        error = ire_init_common(ire, type, ill, zoneid, flags, IPV4_VERSION,
            ipst);
        if (error != 0)
                return (error);

        /* Determine which function pointers to use */
        ire->ire_postfragfn = ip_xmit;          /* Common case */

        switch (ire->ire_type) {
        case IRE_LOCAL:
                ire->ire_sendfn = ire_send_local_v4;
                ire->ire_recvfn = ire_recv_local_v4;
                ASSERT(ire->ire_ill != NULL);
                if (ire->ire_ill->ill_flags & ILLF_NOACCEPT)
                        ire->ire_recvfn = ire_recv_noaccept_v6;
                break;
        case IRE_LOOPBACK:
                ire->ire_sendfn = ire_send_local_v4;
                ire->ire_recvfn = ire_recv_loopback_v4;
                break;
        case IRE_BROADCAST:
                ire->ire_postfragfn = ip_postfrag_loopcheck;
                ire->ire_sendfn = ire_send_broadcast_v4;
                ire->ire_recvfn = ire_recv_broadcast_v4;
                break;
        case IRE_MULTICAST:
                ire->ire_postfragfn = ip_postfrag_loopcheck;
                ire->ire_sendfn = ire_send_multicast_v4;
                ire->ire_recvfn = ire_recv_multicast_v4;
                break;
        default:
                /*
                 * For IRE_IF_ALL and IRE_OFFLINK we forward received
                 * packets by default.
                 */
                ire->ire_sendfn = ire_send_wire_v4;
                ire->ire_recvfn = ire_recv_forward_v4;
                break;
        }
        if (ire->ire_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
                ire->ire_sendfn = ire_send_noroute_v4;
                ire->ire_recvfn = ire_recv_noroute_v4;
        }
        ire->ire_nce_capable = ire_determine_nce_capable(ire);
        return (0);
}

/*
 * Determine ire_nce_capable
 */
boolean_t
ire_determine_nce_capable(ire_t *ire)
{
        int max_masklen;

        if ((ire->ire_flags & (RTF_REJECT|RTF_BLACKHOLE)) ||
            (ire->ire_type & IRE_MULTICAST))
                return (B_TRUE);

        if (ire->ire_ipversion == IPV4_VERSION)
                max_masklen = IPV4_ABITS;
        else
                max_masklen = IPV6_ABITS;

        if ((ire->ire_type & IRE_ONLINK) && ire->ire_masklen == max_masklen)
                return (B_TRUE);
        return (B_FALSE);
}

/*
 * ire_create is called to allocate and initialize a new IRE.
 *
 * NOTE : This is called as writer sometimes though not required
 * by this function.
 */
ire_t *
ire_create(uchar_t *addr, uchar_t *mask, uchar_t *gateway,
    ushort_t type, ill_t *ill, zoneid_t zoneid, uint_t flags,
    ip_stack_t *ipst)
{
        ire_t   *ire;
        int     error;

        ire = kmem_cache_alloc(ire_cache, KM_NOSLEEP);
        if (ire == NULL) {
                DTRACE_PROBE(kmem__cache__alloc);
                return (NULL);
        }
        *ire = ire_null;

        error = ire_init_v4(ire, addr, mask, gateway, type, ill, zoneid, flags,
            ipst);
        if (error != 0) {
                DTRACE_PROBE2(ire__init, ire_t *, ire, int, error);
                kmem_cache_free(ire_cache, ire);
                return (NULL);
        }
        return (ire);
}

/*
 * Common to IPv4 and IPv6
 * Returns zero or errno.
 */
int
ire_init_common(ire_t *ire, ushort_t type, ill_t *ill, zoneid_t zoneid,
    uint_t flags, uchar_t ipversion, ip_stack_t *ipst)
{
        int error;

#ifdef DEBUG
        if (ill != NULL) {
                if (ill->ill_isv6)
                        ASSERT(ipversion == IPV6_VERSION);
                else
                        ASSERT(ipversion == IPV4_VERSION);
        }
#endif /* DEBUG */

        ire->ire_type = type;
        ire->ire_flags = RTF_UP | flags;
        ire->ire_create_time = (uint32_t)gethrestime_sec();
        ire->ire_generation = IRE_GENERATION_INITIAL;

        /*
         * The ill_ire_cnt isn't increased until
         * the IRE is added to ensure that a walker will find
         * all IREs that hold a reference on an ill.
         *
         * Note that ill_ire_multicast doesn't hold a ref on the ill since
         * ire_add() is not called for the IRE_MULTICAST.
         */
        ire->ire_ill = ill;
        ire->ire_zoneid = zoneid;
        ire->ire_ipversion = ipversion;

        mutex_init(&ire->ire_lock, NULL, MUTEX_DEFAULT, NULL);
        ire->ire_refcnt = 1;
        ire->ire_identical_ref = 1;     /* Number of ire_delete's needed */
        ire->ire_ipst = ipst;   /* No netstack_hold */
        ire->ire_trace_disable = B_FALSE;

        return (0);
}

/*
 * This creates an IRE_BROADCAST based on the arguments.
 * A mirror is ire_lookup_bcast().
 *
 * Any supression of unneeded ones is done in ire_add_v4.
 * We add one IRE_BROADCAST per address. ire_send_broadcast_v4()
 * takes care of generating a loopback copy of the packet.
 */
ire_t **
ire_create_bcast(ill_t *ill, ipaddr_t addr, zoneid_t zoneid, ire_t **irep)
{
        ip_stack_t      *ipst = ill->ill_ipst;

        ASSERT(IAM_WRITER_ILL(ill));

        *irep++ = ire_create(
            (uchar_t *)&addr,                   /* dest addr */
            (uchar_t *)&ip_g_all_ones,          /* mask */
            NULL,                               /* no gateway */
            IRE_BROADCAST,
            ill,
            zoneid,
            RTF_KERNEL,
            ipst);

        return (irep);
}

/*
 * This looks up an IRE_BROADCAST based on the arguments.
 * Mirrors ire_create_bcast().
 */
ire_t *
ire_lookup_bcast(ill_t *ill, ipaddr_t addr, zoneid_t zoneid)
{
        ire_t           *ire;
        int             match_args;

        match_args = MATCH_IRE_TYPE | MATCH_IRE_ILL | MATCH_IRE_GW |
            MATCH_IRE_MASK | MATCH_IRE_ZONEONLY;

        if (IS_UNDER_IPMP(ill))
                match_args |= MATCH_IRE_TESTHIDDEN;

        ire = ire_ftable_lookup_v4(
            addr,                               /* dest addr */
            ip_g_all_ones,                      /* mask */
            0,                                  /* no gateway */
            IRE_BROADCAST,
            ill,
            zoneid,
            match_args,
            0,
            ill->ill_ipst,
            NULL);
        return (ire);
}

/* Arrange to call the specified function for every IRE in the world. */
void
ire_walk(pfv_t func, void *arg, ip_stack_t *ipst)
{
        ire_walk_ipvers(func, arg, 0, ALL_ZONES, ipst);
}

void
ire_walk_v4(pfv_t func, void *arg, zoneid_t zoneid, ip_stack_t *ipst)
{
        ire_walk_ipvers(func, arg, IPV4_VERSION, zoneid, ipst);
}

void
ire_walk_v6(pfv_t func, void *arg, zoneid_t zoneid, ip_stack_t *ipst)
{
        ire_walk_ipvers(func, arg, IPV6_VERSION, zoneid, ipst);
}

/*
 * Walk a particular version. version == 0 means both v4 and v6.
 */
static void
ire_walk_ipvers(pfv_t func, void *arg, uchar_t vers, zoneid_t zoneid,
    ip_stack_t *ipst)
{
        if (vers != IPV6_VERSION) {
                /*
                 * ip_forwarding_table variable doesn't matter for IPv4 since
                 * ire_walk_ill_tables uses ips_ip_ftable for IPv4.
                 */
                ire_walk_ill_tables(0, 0, func, arg, IP_MASK_TABLE_SIZE,
                    0, NULL,
                    NULL, zoneid, ipst);
        }
        if (vers != IPV4_VERSION) {
                ire_walk_ill_tables(0, 0, func, arg, IP6_MASK_TABLE_SIZE,
                    ipst->ips_ip6_ftable_hash_size,
                    ipst->ips_ip_forwarding_table_v6,
                    NULL, zoneid, ipst);
        }
}

/*
 * Arrange to call the specified function for every IRE that matches the ill.
 */
void
ire_walk_ill(uint_t match_flags, uint_t ire_type, pfv_t func, void *arg,
    ill_t *ill)
{
        uchar_t vers = (ill->ill_isv6 ? IPV6_VERSION : IPV4_VERSION);

        ire_walk_ill_ipvers(match_flags, ire_type, func, arg, vers, ill);
}

/*
 * Walk a particular ill and version.
 */
static void
ire_walk_ill_ipvers(uint_t match_flags, uint_t ire_type, pfv_t func,
    void *arg, uchar_t vers, ill_t *ill)
{
        ip_stack_t      *ipst = ill->ill_ipst;

        if (vers == IPV4_VERSION) {
                ire_walk_ill_tables(match_flags, ire_type, func, arg,
                    IP_MASK_TABLE_SIZE,
                    0, NULL,
                    ill, ALL_ZONES, ipst);
        }
        if (vers != IPV4_VERSION) {
                ire_walk_ill_tables(match_flags, ire_type, func, arg,
                    IP6_MASK_TABLE_SIZE, ipst->ips_ip6_ftable_hash_size,
                    ipst->ips_ip_forwarding_table_v6,
                    ill, ALL_ZONES, ipst);
        }
}

/*
 * Do the specific matching of IREs to shared-IP zones.
 *
 * We have the same logic as in ire_match_args but implemented slightly
 * differently.
 */
boolean_t
ire_walk_ill_match(uint_t match_flags, uint_t ire_type, ire_t *ire,
    ill_t *ill, zoneid_t zoneid, ip_stack_t *ipst)
{
        ill_t *dst_ill = ire->ire_ill;

        ASSERT(match_flags != 0 || zoneid != ALL_ZONES);

        if (zoneid != ALL_ZONES && zoneid != ire->ire_zoneid &&
            ire->ire_zoneid != ALL_ZONES) {
                /*
                 * We're walking the IREs for a specific zone. The only relevant
                 * IREs are:
                 * - all IREs with a matching ire_zoneid
                 * - IRE_IF_ALL IREs for interfaces with a usable source addr
                 *   with a matching zone
                 * - IRE_OFFLINK with a gateway reachable from the zone
                 * Note that ealier we only did the IRE_OFFLINK check for
                 * IRE_DEFAULT (and only when we had multiple IRE_DEFAULTs).
                 */
                if (ire->ire_type & IRE_ONLINK) {
                        uint_t  ifindex;

                        /*
                         * Note there is no IRE_INTERFACE on vniN thus
                         * can't do an IRE lookup for a matching route.
                         */
                        ifindex = dst_ill->ill_usesrc_ifindex;
                        if (ifindex == 0)
                                return (B_FALSE);

                        /*
                         * If there is a usable source address in the
                         * zone, then it's ok to return an
                         * IRE_INTERFACE
                         */
                        if (!ipif_zone_avail(ifindex, dst_ill->ill_isv6,
                            zoneid, ipst)) {
                                return (B_FALSE);
                        }
                }
                if (dst_ill != NULL && (ire->ire_type & IRE_OFFLINK)) {
                        ipif_t  *tipif;

                        mutex_enter(&dst_ill->ill_lock);
                        for (tipif = dst_ill->ill_ipif;
                            tipif != NULL; tipif = tipif->ipif_next) {
                                if (!IPIF_IS_CONDEMNED(tipif) &&
                                    (tipif->ipif_flags & IPIF_UP) &&
                                    (tipif->ipif_zoneid == zoneid ||
                                    tipif->ipif_zoneid == ALL_ZONES))
                                        break;
                        }
                        mutex_exit(&dst_ill->ill_lock);
                        if (tipif == NULL) {
                                return (B_FALSE);
                        }
                }
        }
        /*
         * Except for ALL_ZONES, we only match the offlink routes
         * where ire_gateway_addr has an IRE_INTERFACE for the zoneid.
         * Since we can have leftover routes after the IP addresses have
         * changed, the global zone will also match offlink routes where the
         * gateway is unreachable from any zone.
         */
        if ((ire->ire_type & IRE_OFFLINK) && zoneid != ALL_ZONES) {
                in6_addr_t gw_addr_v6;
                boolean_t reach;

                if (ire->ire_ipversion == IPV4_VERSION) {
                        reach = ire_gateway_ok_zone_v4(ire->ire_gateway_addr,
                            zoneid, dst_ill, ipst, B_FALSE);
                } else {
                        ASSERT(ire->ire_ipversion == IPV6_VERSION);
                        mutex_enter(&ire->ire_lock);
                        gw_addr_v6 = ire->ire_gateway_addr_v6;
                        mutex_exit(&ire->ire_lock);

                        reach = ire_gateway_ok_zone_v6(&gw_addr_v6, zoneid,
                            dst_ill, ipst, B_FALSE);
                }
                if (!reach) {
                        if (zoneid != GLOBAL_ZONEID)
                                return (B_FALSE);

                        /*
                         * Check if ALL_ZONES reachable - if not then let the
                         * global zone see it.
                         */
                        if (ire->ire_ipversion == IPV4_VERSION) {
                                reach = ire_gateway_ok_zone_v4(
                                    ire->ire_gateway_addr, ALL_ZONES,
                                    dst_ill, ipst, B_FALSE);
                        } else {
                                reach = ire_gateway_ok_zone_v6(&gw_addr_v6,
                                    ALL_ZONES, dst_ill, ipst, B_FALSE);
                        }
                        if (reach) {
                                /*
                                 * Some other zone could see it, hence hide it
                                 * in the global zone.
                                 */
                                return (B_FALSE);
                        }
                }
        }

        if (((!(match_flags & MATCH_IRE_TYPE)) ||
            (ire->ire_type & ire_type)) &&
            ((!(match_flags & MATCH_IRE_ILL)) ||
            (dst_ill == ill ||
            dst_ill != NULL && IS_IN_SAME_ILLGRP(dst_ill, ill)))) {
                return (B_TRUE);
        }
        return (B_FALSE);
}

int
rtfunc(struct radix_node *rn, void *arg)
{
        struct rtfuncarg *rtf = arg;
        struct rt_entry *rt;
        irb_t *irb;
        ire_t *ire;
        boolean_t ret;

        rt = (struct rt_entry *)rn;
        ASSERT(rt != NULL);
        irb = &rt->rt_irb;
        for (ire = irb->irb_ire; ire != NULL; ire = ire->ire_next) {
                if ((rtf->rt_match_flags != 0) ||
                    (rtf->rt_zoneid != ALL_ZONES)) {
                        ret = ire_walk_ill_match(rtf->rt_match_flags,
                            rtf->rt_ire_type, ire,
                            rtf->rt_ill, rtf->rt_zoneid, rtf->rt_ipst);
                } else {
                        ret = B_TRUE;
                }
                if (ret)
                        (*rtf->rt_func)(ire, rtf->rt_arg);
        }
        return (0);
}

/*
 * Walk the ftable entries that match the ill.
 */
void
ire_walk_ill_tables(uint_t match_flags, uint_t ire_type, pfv_t func,
    void *arg, size_t ftbl_sz, size_t htbl_sz, irb_t **ipftbl,
    ill_t *ill, zoneid_t zoneid,
    ip_stack_t *ipst)
{
        irb_t   *irb_ptr;
        irb_t   *irb;
        ire_t   *ire;
        int i, j;
        boolean_t ret;
        struct rtfuncarg rtfarg;

        ASSERT((!(match_flags & MATCH_IRE_ILL)) || (ill != NULL));
        ASSERT(!(match_flags & MATCH_IRE_TYPE) || (ire_type != 0));

        /* knobs such that routine is called only for v6 case */
        if (ipftbl == ipst->ips_ip_forwarding_table_v6) {
                for (i = (ftbl_sz - 1);  i >= 0; i--) {
                        if ((irb_ptr = ipftbl[i]) == NULL)
                                continue;
                        for (j = 0; j < htbl_sz; j++) {
                                irb = &irb_ptr[j];
                                if (irb->irb_ire == NULL)
                                        continue;

                                irb_refhold(irb);
                                for (ire = irb->irb_ire; ire != NULL;
                                    ire = ire->ire_next) {
                                        if (match_flags == 0 &&
                                            zoneid == ALL_ZONES) {
                                                ret = B_TRUE;
                                        } else {
                                                ret =
                                                    ire_walk_ill_match(
                                                    match_flags,
                                                    ire_type, ire, ill,
                                                    zoneid, ipst);
                                        }
                                        if (ret)
                                                (*func)(ire, arg);
                                }
                                irb_refrele(irb);
                        }
                }
        } else {
                bzero(&rtfarg, sizeof (rtfarg));
                rtfarg.rt_func = func;
                rtfarg.rt_arg = arg;
                if (match_flags != 0) {
                        rtfarg.rt_match_flags = match_flags;
                }
                rtfarg.rt_ire_type = ire_type;
                rtfarg.rt_ill = ill;
                rtfarg.rt_zoneid = zoneid;
                rtfarg.rt_ipst = ipst;  /* No netstack_hold */
                (void) ipst->ips_ip_ftable->rnh_walktree_mt(
                    ipst->ips_ip_ftable,
                    rtfunc, &rtfarg, irb_refhold_rn, irb_refrele_rn);
        }
}

/*
 * This function takes a mask and returns
 * number of bits set in the mask. If no
 * bit is set it returns 0.
 * Assumes a contiguous mask.
 */
int
ip_mask_to_plen(ipaddr_t mask)
{
        return (mask == 0 ? 0 : IP_ABITS - (ffs(ntohl(mask)) -1));
}

/*
 * Convert length for a mask to the mask.
 */
ipaddr_t
ip_plen_to_mask(uint_t masklen)
{
        if (masklen == 0)
                return (0);

        return (htonl(IP_HOST_MASK << (IP_ABITS - masklen)));
}

void
ire_atomic_end(irb_t *irb_ptr, ire_t *ire)
{
        ill_t           *ill;

        ill = ire->ire_ill;
        if (ill != NULL)
                mutex_exit(&ill->ill_lock);
        rw_exit(&irb_ptr->irb_lock);
}

/*
 * ire_add_v[46] atomically make sure that the ill associated
 * with the new ire is not going away i.e., we check ILL_CONDEMNED.
 */
int
ire_atomic_start(irb_t *irb_ptr, ire_t *ire)
{
        ill_t           *ill;

        ill = ire->ire_ill;

        rw_enter(&irb_ptr->irb_lock, RW_WRITER);
        if (ill != NULL) {
                mutex_enter(&ill->ill_lock);

                /*
                 * Don't allow IRE's to be created on dying ills, or on
                 * ill's for which the last ipif is going down, or ones which
                 * don't have even a single UP interface
                 */
                if ((ill->ill_state_flags &
                    (ILL_CONDEMNED|ILL_DOWN_IN_PROGRESS)) != 0) {
                        ire_atomic_end(irb_ptr, ire);
                        DTRACE_PROBE1(ire__add__on__dying__ill, ire_t *, ire);
                        return (ENXIO);
                }

                if (IS_UNDER_IPMP(ill)) {
                        int     error = 0;
                        mutex_enter(&ill->ill_phyint->phyint_lock);
                        if (!ipmp_ill_is_active(ill) &&
                            IRE_HIDDEN_TYPE(ire->ire_type) &&
                            !ire->ire_testhidden) {
                                error = EINVAL;
                        }
                        mutex_exit(&ill->ill_phyint->phyint_lock);
                        if (error != 0) {
                                ire_atomic_end(irb_ptr, ire);
                                return (error);
                        }
                }

        }
        return (0);
}

/*
 * Add a fully initialized IRE to the forwarding table.
 * This returns NULL on failure, or a held IRE on success.
 * Normally the returned IRE is the same as the argument. But a different
 * IRE will be returned if the added IRE is deemed identical to an existing
 * one. In that case ire_identical_ref will be increased.
 * The caller always needs to do an ire_refrele() on the returned IRE.
 */
ire_t *
ire_add(ire_t *ire)
{
        if (IRE_HIDDEN_TYPE(ire->ire_type) &&
            ire->ire_ill != NULL && IS_UNDER_IPMP(ire->ire_ill)) {
                /*
                 * IREs hosted on interfaces that are under IPMP
                 * should be hidden so that applications don't
                 * accidentally end up sending packets with test
                 * addresses as their source addresses, or
                 * sending out interfaces that are e.g. IFF_INACTIVE.
                 * Hide them here.
                 */
                ire->ire_testhidden = B_TRUE;
        }

        if (ire->ire_ipversion == IPV6_VERSION)
                return (ire_add_v6(ire));
        else
                return (ire_add_v4(ire));
}

/*
 * Add a fully initialized IPv4 IRE to the forwarding table.
 * This returns NULL on failure, or a held IRE on success.
 * Normally the returned IRE is the same as the argument. But a different
 * IRE will be returned if the added IRE is deemed identical to an existing
 * one. In that case ire_identical_ref will be increased.
 * The caller always needs to do an ire_refrele() on the returned IRE.
 */
static ire_t *
ire_add_v4(ire_t *ire)
{
        ire_t   *ire1;
        irb_t   *irb_ptr;
        ire_t   **irep;
        int     match_flags;
        int     error;
        ip_stack_t      *ipst = ire->ire_ipst;

        if (ire->ire_ill != NULL)
                ASSERT(!MUTEX_HELD(&ire->ire_ill->ill_lock));
        ASSERT(ire->ire_ipversion == IPV4_VERSION);

        /* Make sure the address is properly masked. */
        ire->ire_addr &= ire->ire_mask;

        match_flags = (MATCH_IRE_MASK | MATCH_IRE_TYPE | MATCH_IRE_GW);

        if (ire->ire_ill != NULL) {
                match_flags |= MATCH_IRE_ILL;
        }
        irb_ptr = ire_get_bucket(ire);
        if (irb_ptr == NULL) {
                printf("no bucket for %p\n", (void *)ire);
                ire_delete(ire);
                return (NULL);
        }

        /*
         * Start the atomic add of the ire. Grab the ill lock,
         * the bucket lock. Check for condemned.
         */
        error = ire_atomic_start(irb_ptr, ire);
        if (error != 0) {
                printf("no ire_atomic_start for %p\n", (void *)ire);
                ire_delete(ire);
                irb_refrele(irb_ptr);
                return (NULL);
        }
        /*
         * If we are creating a hidden IRE, make sure we search for
         * hidden IREs when searching for duplicates below.
         * Otherwise, we might find an IRE on some other interface
         * that's not marked hidden.
         */
        if (ire->ire_testhidden)
                match_flags |= MATCH_IRE_TESTHIDDEN;

        /*
         * Atomically check for duplicate and insert in the table.
         */
        for (ire1 = irb_ptr->irb_ire; ire1 != NULL; ire1 = ire1->ire_next) {
                if (IRE_IS_CONDEMNED(ire1))
                        continue;
                /*
                 * Here we need an exact match on zoneid, i.e.,
                 * ire_match_args doesn't fit.
                 */
                if (ire1->ire_zoneid != ire->ire_zoneid)
                        continue;

                if (ire1->ire_type != ire->ire_type)
                        continue;

                /*
                 * Note: We do not allow multiple routes that differ only
                 * in the gateway security attributes; such routes are
                 * considered duplicates.
                 * To change that we explicitly have to treat them as
                 * different here.
                 */
                if (ire_match_args(ire1, ire->ire_addr, ire->ire_mask,
                    ire->ire_gateway_addr, ire->ire_type, ire->ire_ill,
                    ire->ire_zoneid, match_flags)) {
                        /*
                         * Return the old ire after doing a REFHOLD.
                         * As most of the callers continue to use the IRE
                         * after adding, we return a held ire. This will
                         * avoid a lookup in the caller again. If the callers
                         * don't want to use it, they need to do a REFRELE.
                         *
                         * We only allow exactly one IRE_IF_CLONE for any dst,
                         * so, if the is an IF_CLONE, return the ire without
                         * an identical_ref, but with an ire_ref held.
                         */
                        if (ire->ire_type != IRE_IF_CLONE) {
                                atomic_inc_32(&ire1->ire_identical_ref);
                                DTRACE_PROBE2(ire__add__exist, ire_t *, ire1,
                                    ire_t *, ire);
                        }
                        ire_refhold(ire1);
                        ire_atomic_end(irb_ptr, ire);
                        ire_delete(ire);
                        irb_refrele(irb_ptr);
                        return (ire1);
                }
        }

        /*
         * Normally we do head insertion since most things do not care about
         * the order of the IREs in the bucket.  However, due to shared-IP
         * zones (and restrict_interzone_loopback) we can have an IRE_LOCAL
         * as well as IRE_IF_CLONE for the same address. For that reason we
         * do tail insertion for IRE_IF_CLONE.  The IRE_BROADCAST case is a
         * bit of a mystery.
         */
        irep = (ire_t **)irb_ptr;
        if ((ire->ire_type & IRE_IF_CLONE) || (ire->ire_type & IRE_BROADCAST)) {
                while ((ire1 = *irep) != NULL)
                        irep = &ire1->ire_next;
        }
        /* Insert at *irep */
        ire1 = *irep;
        if (ire1 != NULL)
                ire1->ire_ptpn = &ire->ire_next;
        ire->ire_next = ire1;
        /* Link the new one in. */
        ire->ire_ptpn = irep;

        /*
         * ire_walk routines de-reference ire_next without holding
         * a lock. Before we point to the new ire, we want to make
         * sure the store that sets the ire_next of the new ire
         * reaches global visibility, so that ire_walk routines
         * don't see a truncated list of ires i.e if the ire_next
         * of the new ire gets set after we do "*irep = ire" due
         * to re-ordering, the ire_walk thread will see a NULL
         * once it accesses the ire_next of the new ire.
         * membar_producer() makes sure that the following store
         * happens *after* all of the above stores.
         */
        membar_producer();
        *irep = ire;
        ire->ire_bucket = irb_ptr;
        /*
         * We return a bumped up IRE above. Keep it symmetrical
         * so that the callers will always have to release. This
         * helps the callers of this function because they continue
         * to use the IRE after adding and hence they don't have to
         * lookup again after we return the IRE.
         *
         * NOTE : We don't have to use atomics as this is appearing
         * in the list for the first time and no one else can bump
         * up the reference count on this yet.
         */
        ire_refhold_locked(ire);
        BUMP_IRE_STATS(ipst->ips_ire_stats_v4, ire_stats_inserted);

        irb_ptr->irb_ire_cnt++;
        if (irb_ptr->irb_marks & IRB_MARK_DYNAMIC)
                irb_ptr->irb_nire++;

        if (ire->ire_ill != NULL) {
                ire->ire_ill->ill_ire_cnt++;
                ASSERT(ire->ire_ill->ill_ire_cnt != 0); /* Wraparound */
        }

        ire_atomic_end(irb_ptr, ire);

        /* Make any caching of the IREs be notified or updated */
        ire_flush_cache_v4(ire, IRE_FLUSH_ADD);

        if (ire->ire_ill != NULL)
                ASSERT(!MUTEX_HELD(&ire->ire_ill->ill_lock));
        irb_refrele(irb_ptr);
        return (ire);
}

/*
 * irb_refrele is the only caller of the function. ire_unlink calls to
 * do the final cleanup for this ire.
 */
void
ire_cleanup(ire_t *ire)
{
        ire_t *ire_next;
        ip_stack_t *ipst = ire->ire_ipst;

        ASSERT(ire != NULL);

        while (ire != NULL) {
                ire_next = ire->ire_next;
                if (ire->ire_ipversion == IPV4_VERSION) {
                        ire_delete_v4(ire);
                        BUMP_IRE_STATS(ipst->ips_ire_stats_v4,
                            ire_stats_deleted);
                } else {
                        ASSERT(ire->ire_ipversion == IPV6_VERSION);
                        ire_delete_v6(ire);
                        BUMP_IRE_STATS(ipst->ips_ire_stats_v6,
                            ire_stats_deleted);
                }
                /*
                 * Now it's really out of the list. Before doing the
                 * REFRELE, set ire_next to NULL as ire_inactive asserts
                 * so.
                 */
                ire->ire_next = NULL;
                ire_refrele_notr(ire);
                ire = ire_next;
        }
}

/*
 * irb_refrele is the only caller of the function. It calls to unlink
 * all the CONDEMNED ires from this bucket.
 */
ire_t *
ire_unlink(irb_t *irb)
{
        ire_t *ire;
        ire_t *ire1;
        ire_t **ptpn;
        ire_t *ire_list = NULL;

        ASSERT(RW_WRITE_HELD(&irb->irb_lock));
        ASSERT(((irb->irb_marks & IRB_MARK_DYNAMIC) && irb->irb_refcnt == 1) ||
            (irb->irb_refcnt == 0));
        ASSERT(irb->irb_marks & IRB_MARK_CONDEMNED);
        ASSERT(irb->irb_ire != NULL);

        for (ire = irb->irb_ire; ire != NULL; ire = ire1) {
                ire1 = ire->ire_next;
                if (IRE_IS_CONDEMNED(ire)) {
                        ptpn = ire->ire_ptpn;
                        ire1 = ire->ire_next;
                        if (ire1)
                                ire1->ire_ptpn = ptpn;
                        *ptpn = ire1;
                        ire->ire_ptpn = NULL;
                        ire->ire_next = NULL;

                        /*
                         * We need to call ire_delete_v4 or ire_delete_v6 to
                         * clean up dependents and the redirects pointing at
                         * the default gateway. We need to drop the lock
                         * as ire_flush_cache/ire_delete_host_redircts require
                         * so. But we can't drop the lock, as ire_unlink needs
                         * to atomically remove the ires from the list.
                         * So, create a temporary list of CONDEMNED ires
                         * for doing ire_delete_v4/ire_delete_v6 operations
                         * later on.
                         */
                        ire->ire_next = ire_list;
                        ire_list = ire;
                }
        }
        irb->irb_marks &= ~IRB_MARK_CONDEMNED;
        return (ire_list);
}

/*
 * Clean up the radix node for this ire. Must be called by irb_refrele
 * when there are no ire's left in the bucket. Returns TRUE if the bucket
 * is deleted and freed.
 */
boolean_t
irb_inactive(irb_t *irb)
{
        struct rt_entry *rt;
        struct radix_node *rn;
        ip_stack_t *ipst = irb->irb_ipst;

        ASSERT(irb->irb_ipst != NULL);

        rt = IRB2RT(irb);
        rn = (struct radix_node *)rt;

        /* first remove it from the radix tree. */
        RADIX_NODE_HEAD_WLOCK(ipst->ips_ip_ftable);
        rw_enter(&irb->irb_lock, RW_WRITER);
        if (irb->irb_refcnt == 1 && irb->irb_nire == 0) {
                rn = ipst->ips_ip_ftable->rnh_deladdr(rn->rn_key, rn->rn_mask,
                    ipst->ips_ip_ftable);
                DTRACE_PROBE1(irb__free, rt_t *,  rt);
                ASSERT((void *)rn == (void *)rt);
                Free(rt, rt_entry_cache);
                /* irb_lock is freed */
                RADIX_NODE_HEAD_UNLOCK(ipst->ips_ip_ftable);
                return (B_TRUE);
        }
        rw_exit(&irb->irb_lock);
        RADIX_NODE_HEAD_UNLOCK(ipst->ips_ip_ftable);
        return (B_FALSE);
}

/*
 * Delete the specified IRE.
 * We assume that if ire_bucket is not set then ire_ill->ill_ire_cnt was
 * not incremented i.e., that the insertion in the bucket and the increment
 * of that counter is done atomically.
 */
void
ire_delete(ire_t *ire)
{
        ire_t   *ire1;
        ire_t   **ptpn;
        irb_t   *irb;
        ip_stack_t      *ipst = ire->ire_ipst;

        if ((irb = ire->ire_bucket) == NULL) {
                /*
                 * It was never inserted in the list. Should call REFRELE
                 * to free this IRE.
                 */
                ire_make_condemned(ire);
                ire_refrele_notr(ire);
                return;
        }

        /*
         * Move the use counts from an IRE_IF_CLONE to its parent
         * IRE_INTERFACE.
         * We need to do this before acquiring irb_lock.
         */
        if (ire->ire_type & IRE_IF_CLONE) {
                ire_t *parent;

                rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
                if ((parent = ire->ire_dep_parent) != NULL) {
                        parent->ire_ob_pkt_count += ire->ire_ob_pkt_count;
                        parent->ire_ib_pkt_count += ire->ire_ib_pkt_count;
                        ire->ire_ob_pkt_count = 0;
                        ire->ire_ib_pkt_count = 0;
                }
                rw_exit(&ipst->ips_ire_dep_lock);
        }

        rw_enter(&irb->irb_lock, RW_WRITER);
        if (ire->ire_ptpn == NULL) {
                /*
                 * Some other thread has removed us from the list.
                 * It should have done the REFRELE for us.
                 */
                rw_exit(&irb->irb_lock);
                return;
        }

        if (!IRE_IS_CONDEMNED(ire)) {
                /* Is this an IRE representing multiple duplicate entries? */
                ASSERT(ire->ire_identical_ref >= 1);
                if (atomic_dec_32_nv(&ire->ire_identical_ref) != 0) {
                        /* Removed one of the identical parties */
                        rw_exit(&irb->irb_lock);
                        return;
                }

                irb->irb_ire_cnt--;
                ire_make_condemned(ire);
        }

        if (irb->irb_refcnt != 0) {
                /*
                 * The last thread to leave this bucket will
                 * delete this ire.
                 */
                irb->irb_marks |= IRB_MARK_CONDEMNED;
                rw_exit(&irb->irb_lock);
                return;
        }

        /*
         * Normally to delete an ire, we walk the bucket. While we
         * walk the bucket, we normally bump up irb_refcnt and hence
         * we return from above where we mark CONDEMNED and the ire
         * gets deleted from ire_unlink. This case is where somebody
         * knows the ire e.g by doing a lookup, and wants to delete the
         * IRE. irb_refcnt would be 0 in this case if nobody is walking
         * the bucket.
         */
        ptpn = ire->ire_ptpn;
        ire1 = ire->ire_next;
        if (ire1 != NULL)
                ire1->ire_ptpn = ptpn;
        ASSERT(ptpn != NULL);
        *ptpn = ire1;
        ire->ire_ptpn = NULL;
        ire->ire_next = NULL;
        if (ire->ire_ipversion == IPV6_VERSION) {
                BUMP_IRE_STATS(ipst->ips_ire_stats_v6, ire_stats_deleted);
        } else {
                BUMP_IRE_STATS(ipst->ips_ire_stats_v4, ire_stats_deleted);
        }
        rw_exit(&irb->irb_lock);

        /* Cleanup dependents and related stuff */
        if (ire->ire_ipversion == IPV6_VERSION) {
                ire_delete_v6(ire);
        } else {
                ire_delete_v4(ire);
        }
        /*
         * We removed it from the list. Decrement the
         * reference count.
         */
        ire_refrele_notr(ire);
}

/*
 * Delete the specified IRE.
 * All calls should use ire_delete().
 * Sometimes called as writer though not required by this function.
 *
 * NOTE : This function is called only if the ire was added
 * in the list.
 */
static void
ire_delete_v4(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;

        ASSERT(ire->ire_refcnt >= 1);
        ASSERT(ire->ire_ipversion == IPV4_VERSION);

        ire_flush_cache_v4(ire, IRE_FLUSH_DELETE);
        if (ire->ire_type == IRE_DEFAULT) {
                /*
                 * when a default gateway is going away
                 * delete all the host redirects pointing at that
                 * gateway.
                 */
                ire_delete_host_redirects(ire->ire_gateway_addr, ipst);
        }

        /*
         * If we are deleting an IRE_INTERFACE then we make sure we also
         * delete any IRE_IF_CLONE that has been created from it.
         * Those are always in ire_dep_children.
         */
        if ((ire->ire_type & IRE_INTERFACE) && ire->ire_dep_children != NULL)
                ire_dep_delete_if_clone(ire);

        /* Remove from parent dependencies and child */
        rw_enter(&ipst->ips_ire_dep_lock, RW_WRITER);
        if (ire->ire_dep_parent != NULL)
                ire_dep_remove(ire);

        while (ire->ire_dep_children != NULL)
                ire_dep_remove(ire->ire_dep_children);
        rw_exit(&ipst->ips_ire_dep_lock);
}

/*
 * ire_refrele is the only caller of the function. It calls
 * to free the ire when the reference count goes to zero.
 */
void
ire_inactive(ire_t *ire)
{
        ill_t   *ill;
        irb_t   *irb;
        ip_stack_t      *ipst = ire->ire_ipst;

        ASSERT(ire->ire_refcnt == 0);
        ASSERT(ire->ire_ptpn == NULL);
        ASSERT(ire->ire_next == NULL);

        /* Count how many condemned ires for kmem_cache callback */
        ASSERT(IRE_IS_CONDEMNED(ire));
        atomic_add_32(&ipst->ips_num_ire_condemned, -1);

        /*
         * ire_nce_cache is cleared in ire_delete, and we make sure we don't
         * set it once the ire is marked condemned.
         */
        ASSERT(ire->ire_nce_cache == NULL);

        /*
         * Since any parent would have a refhold on us they would already
         * have been removed.
         */
        ASSERT(ire->ire_dep_parent == NULL);
        ASSERT(ire->ire_dep_sib_next == NULL);
        ASSERT(ire->ire_dep_sib_ptpn == NULL);

        /*
         * Since any children would have a refhold on us they should have
         * already been removed.
         */
        ASSERT(ire->ire_dep_children == NULL);

        /*
         * ill_ire_ref is increased when the IRE is inserted in the
         * bucket - not when the IRE is created.
         */
        irb = ire->ire_bucket;
        ill = ire->ire_ill;
        if (irb != NULL && ill != NULL) {
                mutex_enter(&ill->ill_lock);
                ASSERT(ill->ill_ire_cnt != 0);
                DTRACE_PROBE3(ill__decr__cnt, (ill_t *), ill,
                    (char *), "ire", (void *), ire);
                ill->ill_ire_cnt--;
                if (ILL_DOWN_OK(ill)) {
                        /* Drops the ill lock */
                        ipif_ill_refrele_tail(ill);
                } else {
                        mutex_exit(&ill->ill_lock);
                }
        }
        ire->ire_ill = NULL;

        /* This should be true for both V4 and V6 */
        if (irb != NULL && (irb->irb_marks & IRB_MARK_DYNAMIC)) {
                rw_enter(&irb->irb_lock, RW_WRITER);
                irb->irb_nire--;
                /*
                 * Instead of examining the conditions for freeing
                 * the radix node here, we do it by calling
                 * irb_refrele which is a single point in the code
                 * that embeds that logic. Bump up the refcnt to
                 * be able to call irb_refrele
                 */
                irb_refhold_locked(irb);
                rw_exit(&irb->irb_lock);
                irb_refrele(irb);
        }

#ifdef DEBUG
        ire_trace_cleanup(ire);
#endif
        mutex_destroy(&ire->ire_lock);
        if (ire->ire_ipversion == IPV6_VERSION) {
                BUMP_IRE_STATS(ipst->ips_ire_stats_v6, ire_stats_freed);
        } else {
                BUMP_IRE_STATS(ipst->ips_ire_stats_v4, ire_stats_freed);
        }
        kmem_cache_free(ire_cache, ire);
}

/*
 * ire_update_generation is the callback function provided by
 * ire_get_bucket() to update the generation number of any
 * matching shorter route when a new route is added.
 *
 * This fucntion always returns a failure return (B_FALSE)
 * to force the caller (rn_matchaddr_args)
 * to back-track up the tree looking for shorter matches.
 */
/* ARGSUSED */
static boolean_t
ire_update_generation(struct radix_node *rn, void *arg)
{
        struct rt_entry *rt = (struct rt_entry *)rn;

        /* We need to handle all in the same bucket */
        irb_increment_generation(&rt->rt_irb);
        return (B_FALSE);
}

/*
 * Take care of all the generation numbers in the bucket.
 */
void
irb_increment_generation(irb_t *irb)
{
        ire_t *ire;
        ip_stack_t *ipst;

        if (irb == NULL || irb->irb_ire_cnt == 0)
                return;

        ipst = irb->irb_ipst;
        /*
         * we cannot do an irb_refhold/irb_refrele here as the caller
         * already has the global RADIX_NODE_HEAD_WLOCK, and the irb_refrele
         * may result in an attempt to free the irb_t, which also needs
         * the RADIX_NODE_HEAD lock. However, since we want to traverse the
         * irb_ire list without fear of having a condemned ire removed from
         * the list, we acquire the irb_lock as WRITER. Moreover, since
         * the ire_generation increments are done under the ire_dep_lock,
         * acquire the locks in the prescribed lock order first.
         */
        rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
        rw_enter(&irb->irb_lock, RW_WRITER);
        for (ire = irb->irb_ire; ire != NULL; ire = ire->ire_next) {
                if (!IRE_IS_CONDEMNED(ire))
                        ire_increment_generation(ire);  /* Ourselves */
                ire_dep_incr_generation_locked(ire);    /* Dependants */
        }
        rw_exit(&irb->irb_lock);
        rw_exit(&ipst->ips_ire_dep_lock);
}

/*
 * When an IRE is added or deleted this routine is called to make sure
 * any caching of IRE information is notified or updated.
 *
 * The flag argument indicates if the flush request is due to addition
 * of new route (IRE_FLUSH_ADD), deletion of old route (IRE_FLUSH_DELETE),
 * or a change to ire_gateway_addr (IRE_FLUSH_GWCHANGE).
 */
void
ire_flush_cache_v4(ire_t *ire, int flag)
{
        irb_t *irb = ire->ire_bucket;
        struct rt_entry *rt = IRB2RT(irb);
        ip_stack_t *ipst = ire->ire_ipst;

        /*
         * IRE_IF_CLONE ire's don't provide any new information
         * than the parent from which they are cloned, so don't
         * perturb the generation numbers.
         */
        if (ire->ire_type & IRE_IF_CLONE)
                return;

        /*
         * Ensure that an ire_add during a lookup serializes the updates of the
         * generation numbers under the radix head lock so that the lookup gets
         * either the old ire and old generation number, or a new ire and new
         * generation number.
         */
        RADIX_NODE_HEAD_WLOCK(ipst->ips_ip_ftable);

        /*
         * If a route was just added, we need to notify everybody that
         * has cached an IRE_NOROUTE since there might now be a better
         * route for them.
         */
        if (flag == IRE_FLUSH_ADD) {
                ire_increment_generation(ipst->ips_ire_reject_v4);
                ire_increment_generation(ipst->ips_ire_blackhole_v4);
        }

        /* Adding a default can't otherwise provide a better route */
        if (ire->ire_type == IRE_DEFAULT && flag == IRE_FLUSH_ADD) {
                RADIX_NODE_HEAD_UNLOCK(ipst->ips_ip_ftable);
                return;
        }

        switch (flag) {
        case IRE_FLUSH_DELETE:
        case IRE_FLUSH_GWCHANGE:
                /*
                 * Update ire_generation for all ire_dep_children chains
                 * starting with this IRE
                 */
                ire_dep_incr_generation(ire);
                break;
        case IRE_FLUSH_ADD:
                /*
                 * Update the generation numbers of all shorter matching routes.
                 * ire_update_generation takes care of the dependants by
                 * using ire_dep_incr_generation.
                 */
                (void) ipst->ips_ip_ftable->rnh_matchaddr_args(&rt->rt_dst,
                    ipst->ips_ip_ftable, ire_update_generation, NULL);
                break;
        }
        RADIX_NODE_HEAD_UNLOCK(ipst->ips_ip_ftable);
}

/*
 * Matches the arguments passed with the values in the ire.
 *
 * Note: for match types that match using "ill" passed in, ill
 * must be checked for non-NULL before calling this routine.
 */
boolean_t
ire_match_args(ire_t *ire, ipaddr_t addr, ipaddr_t mask, ipaddr_t gateway,
    int type, const ill_t *ill, zoneid_t zoneid, int match_flags)
{
        ill_t *ire_ill = NULL, *dst_ill;
        ip_stack_t *ipst = ire->ire_ipst;

        ASSERT(ire->ire_ipversion == IPV4_VERSION);
        ASSERT((ire->ire_addr & ~ire->ire_mask) == 0);
        ASSERT((!(match_flags & (MATCH_IRE_ILL|MATCH_IRE_SRC_ILL))) ||
            (ill != NULL && !ill->ill_isv6));

        /*
         * If MATCH_IRE_TESTHIDDEN is set, then only return the IRE if it is
         * in fact hidden, to ensure the caller gets the right one.
         */
        if (ire->ire_testhidden) {
                if (!(match_flags & MATCH_IRE_TESTHIDDEN))
                        return (B_FALSE);
        }

        if (zoneid != ALL_ZONES && zoneid != ire->ire_zoneid &&
            ire->ire_zoneid != ALL_ZONES) {
                /*
                 * If MATCH_IRE_ZONEONLY has been set and the supplied zoneid
                 * does not match that of ire_zoneid, a failure to
                 * match is reported at this point. Otherwise, since some IREs
                 * that are available in the global zone can be used in local
                 * zones, additional checks need to be performed:
                 *
                 * IRE_LOOPBACK
                 *      entries should never be matched in this situation.
                 *      Each zone has its own IRE_LOOPBACK.
                 *
                 * IRE_LOCAL
                 *      We allow them for any zoneid. ire_route_recursive
                 *      does additional checks when
                 *      ip_restrict_interzone_loopback is set.
                 *
                 * If ill_usesrc_ifindex is set
                 *      Then we check if the zone has a valid source address
                 *      on the usesrc ill.
                 *
                 * If ire_ill is set, then check that the zone has an ipif
                 *      on that ill.
                 *
                 * Outside of this function (in ire_round_robin) we check
                 * that any IRE_OFFLINK has a gateway that reachable from the
                 * zone when we have multiple choices (ECMP).
                 */
                if (match_flags & MATCH_IRE_ZONEONLY)
                        return (B_FALSE);
                if (ire->ire_type & IRE_LOOPBACK)
                        return (B_FALSE);

                if (ire->ire_type & IRE_LOCAL)
                        goto matchit;

                /*
                 * The normal case of IRE_ONLINK has a matching zoneid.
                 * Here we handle the case when shared-IP zones have been
                 * configured with IP addresses on vniN. In that case it
                 * is ok for traffic from a zone to use IRE_ONLINK routes
                 * if the ill has a usesrc pointing at vniN
                 */
                dst_ill = ire->ire_ill;
                if (ire->ire_type & IRE_ONLINK) {
                        uint_t  ifindex;

                        /*
                         * Note there is no IRE_INTERFACE on vniN thus
                         * can't do an IRE lookup for a matching route.
                         */
                        ifindex = dst_ill->ill_usesrc_ifindex;
                        if (ifindex == 0)
                                return (B_FALSE);

                        /*
                         * If there is a usable source address in the
                         * zone, then it's ok to return this IRE_INTERFACE
                         */
                        if (!ipif_zone_avail(ifindex, dst_ill->ill_isv6,
                            zoneid, ipst)) {
                                ip3dbg(("ire_match_args: no usrsrc for zone"
                                    " dst_ill %p\n", (void *)dst_ill));
                                return (B_FALSE);
                        }
                }
                /*
                 * For example, with
                 * route add 11.0.0.0 gw1 -ifp bge0
                 * route add 11.0.0.0 gw2 -ifp bge1
                 * this code would differentiate based on
                 * where the sending zone has addresses.
                 * Only if the zone has an address on bge0 can it use the first
                 * route. It isn't clear if this behavior is documented
                 * anywhere.
                 */
                if (dst_ill != NULL && (ire->ire_type & IRE_OFFLINK)) {
                        ipif_t  *tipif;

                        mutex_enter(&dst_ill->ill_lock);
                        for (tipif = dst_ill->ill_ipif;
                            tipif != NULL; tipif = tipif->ipif_next) {
                                if (!IPIF_IS_CONDEMNED(tipif) &&
                                    (tipif->ipif_flags & IPIF_UP) &&
                                    (tipif->ipif_zoneid == zoneid ||
                                    tipif->ipif_zoneid == ALL_ZONES))
                                        break;
                        }
                        mutex_exit(&dst_ill->ill_lock);
                        if (tipif == NULL) {
                                return (B_FALSE);
                        }
                }
        }

matchit:
        ire_ill = ire->ire_ill;
        if (match_flags & MATCH_IRE_ILL) {

                /*
                 * If asked to match an ill, we *must* match
                 * on the ire_ill for ipmp test addresses, or
                 * any of the ill in the group for data addresses.
                 * If we don't, we may as well fail.
                 * However, we need an exception for IRE_LOCALs to ensure
                 * we loopback packets even sent to test addresses on different
                 * interfaces in the group.
                 */
                if ((match_flags & MATCH_IRE_TESTHIDDEN) &&
                    !(ire->ire_type & IRE_LOCAL)) {
                        if (ire->ire_ill != ill)
                                return (B_FALSE);
                } else  {
                        match_flags &= ~MATCH_IRE_TESTHIDDEN;
                        /*
                         * We know that ill is not NULL, but ire_ill could be
                         * NULL
                         */
                        if (ire_ill == NULL || !IS_ON_SAME_LAN(ill, ire_ill))
                                return (B_FALSE);
                }
        }
        if (match_flags & MATCH_IRE_SRC_ILL) {
                if (ire_ill == NULL)
                        return (B_FALSE);
                if (!IS_ON_SAME_LAN(ill, ire_ill)) {
                        if (ire_ill->ill_usesrc_ifindex == 0 ||
                            (ire_ill->ill_usesrc_ifindex !=
                            ill->ill_phyint->phyint_ifindex))
                                return (B_FALSE);
                }
        }

        if ((ire->ire_addr == (addr & mask)) &&
            ((!(match_flags & MATCH_IRE_GW)) ||
            (ire->ire_gateway_addr == gateway)) &&
            ((!(match_flags & MATCH_IRE_DIRECT)) ||
            !(ire->ire_flags & RTF_INDIRECT)) &&
            ((!(match_flags & MATCH_IRE_TYPE)) || (ire->ire_type & type)) &&
            ((!(match_flags & MATCH_IRE_TESTHIDDEN)) || ire->ire_testhidden) &&
            ((!(match_flags & MATCH_IRE_MASK)) || (ire->ire_mask == mask))) {
                /* We found the matched IRE */
                return (B_TRUE);
        }
        return (B_FALSE);
}

/*
 * Check if the IRE_LOCAL uses the same ill as another route would use.
 * If there is no alternate route, or the alternate is a REJECT or BLACKHOLE,
 * then we don't allow this IRE_LOCAL to be used.
 * We always return an IRE; will be RTF_REJECT if no route available.
 */
ire_t *
ire_alt_local(ire_t *ire, zoneid_t zoneid, const ill_t *ill,
    uint_t *generationp)
{
        ip_stack_t      *ipst = ire->ire_ipst;
        ire_t           *alt_ire;
        uint_t          ire_type;
        uint_t          generation;
        uint_t          match_flags;

        ASSERT(ire->ire_type & IRE_LOCAL);
        ASSERT(ire->ire_ill != NULL);

        /*
         * Need to match on everything but local.
         * This might result in the creation of a IRE_IF_CLONE for the
         * same address as the IRE_LOCAL when restrict_interzone_loopback is
         * set. ire_add_*() ensures that the IRE_IF_CLONE are tail inserted
         * to make sure the IRE_LOCAL is always found first.
         */
        ire_type = (IRE_ONLINK | IRE_OFFLINK) & ~(IRE_LOCAL|IRE_LOOPBACK);
        match_flags = MATCH_IRE_TYPE;
        if (ill != NULL)
                match_flags |= MATCH_IRE_ILL;

        if (ire->ire_ipversion == IPV4_VERSION) {
                alt_ire = ire_route_recursive_v4(ire->ire_addr, ire_type,
                    ill, zoneid, match_flags, IRR_ALLOCATE, 0, ipst, NULL,
                    &generation);
        } else {
                alt_ire = ire_route_recursive_v6(&ire->ire_addr_v6, ire_type,
                    ill, zoneid, match_flags, IRR_ALLOCATE, 0, ipst, NULL,
                    &generation);
        }
        ASSERT(alt_ire != NULL);

        if (alt_ire->ire_ill == ire->ire_ill) {
                /* Going out the same ILL - ok to send to IRE_LOCAL */
                ire_refrele(alt_ire);
        } else {
                /* Different ill - ignore IRE_LOCAL */
                ire_refrele(ire);
                ire = alt_ire;
                if (generationp != NULL)
                        *generationp = generation;
        }
        return (ire);
}

boolean_t
ire_find_zoneid(struct radix_node *rn, void *arg)
{
        struct rt_entry *rt = (struct rt_entry *)rn;
        irb_t *irb;
        ire_t *ire;
        ire_ftable_args_t *margs = arg;

        ASSERT(rt != NULL);

        irb = &rt->rt_irb;

        if (irb->irb_ire_cnt == 0)
                return (B_FALSE);

        rw_enter(&irb->irb_lock, RW_READER);
        for (ire = irb->irb_ire; ire != NULL; ire = ire->ire_next) {
                if (IRE_IS_CONDEMNED(ire))
                        continue;

                if (!(ire->ire_type & IRE_INTERFACE))
                        continue;

                if (ire->ire_zoneid != ALL_ZONES &&
                    ire->ire_zoneid != margs->ift_zoneid)
                        continue;

                if (margs->ift_ill != NULL && margs->ift_ill != ire->ire_ill)
                        continue;

                rw_exit(&irb->irb_lock);
                return (B_TRUE);
        }
        rw_exit(&irb->irb_lock);
        return (B_FALSE);
}

/*
 * Check if the zoneid (not ALL_ZONES) has an IRE_INTERFACE for the specified
 * gateway address. If ill is non-NULL we also match on it.
 * The caller must hold a read lock on RADIX_NODE_HEAD if lock_held is set.
 */
boolean_t
ire_gateway_ok_zone_v4(ipaddr_t gateway, zoneid_t zoneid, ill_t *ill,
    ip_stack_t *ipst, boolean_t lock_held)
{
        struct rt_sockaddr rdst;
        struct rt_entry *rt;
        ire_ftable_args_t margs;

        ASSERT(ill == NULL || !ill->ill_isv6);
        if (lock_held)
                ASSERT(RW_READ_HELD(&ipst->ips_ip_ftable->rnh_lock));
        else
                RADIX_NODE_HEAD_RLOCK(ipst->ips_ip_ftable);

        bzero(&rdst, sizeof (rdst));
        rdst.rt_sin_len = sizeof (rdst);
        rdst.rt_sin_family = AF_INET;
        rdst.rt_sin_addr.s_addr = gateway;

        /* We only use margs for ill and zoneidmatching in ire_find_zoneid */
        bzero(&margs, sizeof (margs));
        margs.ift_ill = ill;
        margs.ift_zoneid = zoneid;
        rt = (struct rt_entry *)ipst->ips_ip_ftable->rnh_matchaddr_args(&rdst,
            ipst->ips_ip_ftable, ire_find_zoneid, (void *)&margs);

        if (!lock_held)
                RADIX_NODE_HEAD_UNLOCK(ipst->ips_ip_ftable);

        return (rt != NULL);
}

/*
 * ire_walk routine to delete a fraction of redirect IREs and IRE_CLONE_IF IREs.
 * The fraction argument tells us what fraction of the IREs to delete.
 * Common for IPv4 and IPv6.
 * Used when memory backpressure.
 */
static void
ire_delete_reclaim(ire_t *ire, char *arg)
{
        ip_stack_t      *ipst = ire->ire_ipst;
        uint_t          fraction = *(uint_t *)arg;
        uint_t          rand;

        if ((ire->ire_flags & RTF_DYNAMIC) ||
            (ire->ire_type & IRE_IF_CLONE)) {

                /* Pick a random number */
                rand = (uint_t)ddi_get_lbolt() +
                    IRE_ADDR_HASH_V6(ire->ire_addr_v6, 256);

                /* Use truncation */
                if ((rand/fraction)*fraction == rand) {
                        IP_STAT(ipst, ip_ire_reclaim_deleted);
                        ire_delete(ire);
                }
        }

}

/*
 * kmem_cache callback to free up memory.
 *
 * Free a fraction (ips_ip_ire_reclaim_fraction) of things IP added dynamically
 * (RTF_DYNAMIC and IRE_IF_CLONE).
 */
static void
ip_ire_reclaim_stack(ip_stack_t *ipst)
{
        uint_t  fraction = ipst->ips_ip_ire_reclaim_fraction;

        IP_STAT(ipst, ip_ire_reclaim_calls);

        ire_walk(ire_delete_reclaim, &fraction, ipst);

        /*
         * Walk all CONNs that can have a reference on an ire, nce or dce.
         * Get them to update any stale references to drop any refholds they
         * have.
         */
        ipcl_walk(conn_ixa_cleanup, (void *)B_FALSE, ipst);
}

/*
 * Called by the memory allocator subsystem directly, when the system
 * is running low on memory.
 */
/* ARGSUSED */
void
ip_ire_reclaim(void *args)
{
        netstack_handle_t nh;
        netstack_t *ns;
        ip_stack_t *ipst;

        netstack_next_init(&nh);
        while ((ns = netstack_next(&nh)) != NULL) {
                /*
                 * netstack_next() can return a netstack_t with a NULL
                 * netstack_ip at boot time.
                 */
                if ((ipst = ns->netstack_ip) == NULL) {
                        netstack_rele(ns);
                        continue;
                }
                ip_ire_reclaim_stack(ipst);
                netstack_rele(ns);
        }
        netstack_next_fini(&nh);
}

static void
power2_roundup(uint32_t *value)
{
        int i;

        for (i = 1; i < 31; i++) {
                if (*value <= (1 << i))
                        break;
        }
        *value = (1 << i);
}

/* Global init for all zones */
void
ip_ire_g_init()
{
        /*
         * Create kmem_caches.  ip_ire_reclaim() and ip_nce_reclaim()
         * will give disposable IREs back to system when needed.
         * This needs to be done here before anything else, since
         * ire_add() expects the cache to be created.
         */
        ire_cache = kmem_cache_create("ire_cache",
            sizeof (ire_t), 0, NULL, NULL,
            ip_ire_reclaim, NULL, NULL, 0);

        ncec_cache = kmem_cache_create("ncec_cache",
            sizeof (ncec_t), 0, NULL, NULL,
            ip_nce_reclaim, NULL, NULL, 0);
        nce_cache = kmem_cache_create("nce_cache",
            sizeof (nce_t), 0, NULL, NULL,
            NULL, NULL, NULL, 0);

        rt_entry_cache = kmem_cache_create("rt_entry",
            sizeof (struct rt_entry), 0, NULL, NULL, NULL, NULL, NULL, 0);

        /*
         * Have radix code setup kmem caches etc.
         */
        rn_init();
}

void
ip_ire_init(ip_stack_t *ipst)
{
        ire_t   *ire;
        int     error;

        mutex_init(&ipst->ips_ire_ft_init_lock, NULL, MUTEX_DEFAULT, 0);

        (void) rn_inithead((void **)&ipst->ips_ip_ftable, 32);

        /*
         * Make sure that the forwarding table size is a power of 2.
         * The IRE*_ADDR_HASH() macroes depend on that.
         */
        ipst->ips_ip6_ftable_hash_size = ip6_ftable_hash_size;
        power2_roundup(&ipst->ips_ip6_ftable_hash_size);

        /*
         * Allocate/initialize a pair of IRE_NOROUTEs for each of IPv4 and IPv6.
         * The ire_reject_v* has RTF_REJECT set, and the ire_blackhole_v* has
         * RTF_BLACKHOLE set. We use the latter for transient errors such
         * as memory allocation failures and tripping on IRE_IS_CONDEMNED
         * entries.
         */
        ire = kmem_cache_alloc(ire_cache, KM_SLEEP);
        *ire = ire_null;
        error = ire_init_v4(ire, 0, 0, 0, IRE_NOROUTE, NULL, ALL_ZONES,
            RTF_REJECT|RTF_UP, ipst);
        ASSERT(error == 0);
        ipst->ips_ire_reject_v4 = ire;

        ire = kmem_cache_alloc(ire_cache, KM_SLEEP);
        *ire = ire_null;
        error = ire_init_v6(ire, 0, 0, 0, IRE_NOROUTE, NULL, ALL_ZONES,
            RTF_REJECT|RTF_UP, ipst);
        ASSERT(error == 0);
        ipst->ips_ire_reject_v6 = ire;

        ire = kmem_cache_alloc(ire_cache, KM_SLEEP);
        *ire = ire_null;
        error = ire_init_v4(ire, 0, 0, 0, IRE_NOROUTE, NULL, ALL_ZONES,
            RTF_BLACKHOLE|RTF_UP, ipst);
        ASSERT(error == 0);
        ipst->ips_ire_blackhole_v4 = ire;

        ire = kmem_cache_alloc(ire_cache, KM_SLEEP);
        *ire = ire_null;
        error = ire_init_v6(ire, 0, 0, 0, IRE_NOROUTE, NULL, ALL_ZONES,
            RTF_BLACKHOLE|RTF_UP, ipst);
        ASSERT(error == 0);
        ipst->ips_ire_blackhole_v6 = ire;

        rw_init(&ipst->ips_ip6_ire_head_lock, NULL, RW_DEFAULT, NULL);
        rw_init(&ipst->ips_ire_dep_lock, NULL, RW_DEFAULT, NULL);
}

void
ip_ire_g_fini(void)
{
        kmem_cache_destroy(ire_cache);
        kmem_cache_destroy(ncec_cache);
        kmem_cache_destroy(nce_cache);
        kmem_cache_destroy(rt_entry_cache);

        rn_fini();
}

void
ip_ire_fini(ip_stack_t *ipst)
{
        int i;

        ire_make_condemned(ipst->ips_ire_reject_v6);
        ire_refrele_notr(ipst->ips_ire_reject_v6);
        ipst->ips_ire_reject_v6 = NULL;

        ire_make_condemned(ipst->ips_ire_reject_v4);
        ire_refrele_notr(ipst->ips_ire_reject_v4);
        ipst->ips_ire_reject_v4 = NULL;

        ire_make_condemned(ipst->ips_ire_blackhole_v6);
        ire_refrele_notr(ipst->ips_ire_blackhole_v6);
        ipst->ips_ire_blackhole_v6 = NULL;

        ire_make_condemned(ipst->ips_ire_blackhole_v4);
        ire_refrele_notr(ipst->ips_ire_blackhole_v4);
        ipst->ips_ire_blackhole_v4 = NULL;

        /*
         * Delete all IREs - assumes that the ill/ipifs have
         * been removed so what remains are just the ftable to handle.
         */
        ire_walk(ire_delete, NULL, ipst);

        rn_freehead(ipst->ips_ip_ftable);
        ipst->ips_ip_ftable = NULL;

        rw_destroy(&ipst->ips_ire_dep_lock);
        rw_destroy(&ipst->ips_ip6_ire_head_lock);

        mutex_destroy(&ipst->ips_ire_ft_init_lock);

        for (i = 0; i < IP6_MASK_TABLE_SIZE; i++) {
                irb_t *ptr;
                int j;

                if ((ptr = ipst->ips_ip_forwarding_table_v6[i]) == NULL)
                        continue;

                for (j = 0; j < ipst->ips_ip6_ftable_hash_size; j++) {
                        ASSERT(ptr[j].irb_ire == NULL);
                        rw_destroy(&ptr[j].irb_lock);
                }
                mi_free(ptr);
                ipst->ips_ip_forwarding_table_v6[i] = NULL;
        }
}

#ifdef DEBUG
void
ire_trace_ref(ire_t *ire)
{
        mutex_enter(&ire->ire_lock);
        if (ire->ire_trace_disable) {
                mutex_exit(&ire->ire_lock);
                return;
        }

        if (th_trace_ref(ire, ire->ire_ipst)) {
                mutex_exit(&ire->ire_lock);
        } else {
                ire->ire_trace_disable = B_TRUE;
                mutex_exit(&ire->ire_lock);
                ire_trace_cleanup(ire);
        }
}

void
ire_untrace_ref(ire_t *ire)
{
        mutex_enter(&ire->ire_lock);
        if (!ire->ire_trace_disable)
                th_trace_unref(ire);
        mutex_exit(&ire->ire_lock);
}

static void
ire_trace_cleanup(const ire_t *ire)
{
        th_trace_cleanup(ire, ire->ire_trace_disable);
}
#endif /* DEBUG */

/*
 * Find, or create if needed, the nce_t pointer to the neighbor cache
 * entry ncec_t for an IPv4 address. The nce_t will be created on the ill_t
 * in the non-IPMP case, or on the cast-ill in the IPMP bcast/mcast case, or
 * on the next available under-ill (selected by the IPMP rotor) in the
 * unicast IPMP case.
 *
 * If a neighbor-cache entry has to be created (i.e., one does not already
 * exist in the nce list) the ncec_lladdr and ncec_state of the neighbor cache
 * entry are initialized in nce_add_v4(). The broadcast, multicast, and
 * link-layer type determine the contents of {ncec_state, ncec_lladdr} of
 * the ncec_t created. The ncec_lladdr is non-null for all link types with
 * non-zero ill_phys_addr_length, though the contents may be zero in cases
 * where the link-layer type is not known at the time of creation
 * (e.g., IRE_IFRESOLVER links)
 *
 * All IRE_BROADCAST entries have ncec_state = ND_REACHABLE, and the nce_lladr
 * has the physical broadcast address of the outgoing interface.
 * For unicast ire entries,
 *   - if the outgoing interface is of type IRE_IF_RESOLVER, a newly created
 *     ncec_t with 0 nce_lladr contents, and will be in the ND_INITIAL state.
 *   - if the outgoing interface is a IRE_IF_NORESOLVER interface, no link
 *     layer resolution is necessary, so that the ncec_t will be in the
 *     ND_REACHABLE state
 *
 * The link layer information needed for broadcast addresses, and for
 * packets sent on IRE_IF_NORESOLVER interfaces is a constant mapping that
 * never needs re-verification for the lifetime of the ncec_t. These are
 * therefore marked NCE_F_NONUD.
 *
 * The nce returned will be created such that the nce_ill == ill that
 * is passed in. Note that the nce itself may not have ncec_ill == ill
 * where IPMP links are involved.
 */
static nce_t *
ire_nce_init(ill_t *ill, const void *addr, int ire_type)
{
        int             err;
        nce_t           *nce = NULL;
        uint16_t        ncec_flags;
        uchar_t         *hwaddr;
        boolean_t       need_refrele = B_FALSE;
        ill_t           *in_ill = ill;
        boolean_t       is_unicast;
        uint_t          hwaddr_len;

        is_unicast = ((ire_type & (IRE_MULTICAST|IRE_BROADCAST)) == 0);
        if (IS_IPMP(ill) ||
            ((ire_type & IRE_BROADCAST) && IS_UNDER_IPMP(ill))) {
                if ((ill = ipmp_ill_hold_xmit_ill(ill, is_unicast)) == NULL)
                        return (NULL);
                need_refrele = B_TRUE;
        }
        ncec_flags = (ill->ill_flags & ILLF_NONUD) ? NCE_F_NONUD : 0;

        switch (ire_type) {
        case IRE_BROADCAST:
                ASSERT(!ill->ill_isv6);
                ncec_flags |= (NCE_F_BCAST|NCE_F_NONUD);
                break;
        case IRE_MULTICAST:
                ncec_flags |= (NCE_F_MCAST|NCE_F_NONUD);
                break;
        }

        if (ill->ill_net_type == IRE_IF_NORESOLVER && is_unicast) {
                hwaddr = ill->ill_dest_addr;
        } else {
                hwaddr = NULL;
        }
        hwaddr_len = ill->ill_phys_addr_length;

retry:
        /* nce_state will be computed by nce_add_common() */
        if (!ill->ill_isv6) {
                err = nce_lookup_then_add_v4(ill, hwaddr, hwaddr_len, addr,
                    ncec_flags, ND_UNCHANGED, &nce);
        } else {
                err = nce_lookup_then_add_v6(ill, hwaddr, hwaddr_len, addr,
                    ncec_flags, ND_UNCHANGED, &nce);
        }

        switch (err) {
        case 0:
                break;
        case EEXIST:
                /*
                 * When subnets change or partially overlap what was once
                 * a broadcast address could now be a unicast, or vice versa.
                 */
                if (((ncec_flags ^ nce->nce_common->ncec_flags) &
                    NCE_F_BCAST) != 0) {
                        ASSERT(!ill->ill_isv6);
                        ncec_delete(nce->nce_common);
                        nce_refrele(nce);
                        goto retry;
                }
                break;
        default:
                DTRACE_PROBE2(nce__init__fail, ill_t *, ill, int, err);
                if (need_refrele)
                        ill_refrele(ill);
                return (NULL);
        }
        /*
         * If the ill was an under-ill of an IPMP group, we need to verify
         * that it is still active so that we select an active interface in
         * the group. However, since ipmp_ill_is_active ASSERTs for
         * IS_UNDER_IPMP(), we first need to verify that the ill is an
         * under-ill, and since this is being done in the data path, the
         * only way to ascertain this is by holding the ill_g_lock.
         */
        rw_enter(&ill->ill_ipst->ips_ill_g_lock, RW_READER);
        mutex_enter(&ill->ill_lock);
        mutex_enter(&ill->ill_phyint->phyint_lock);
        if (need_refrele && IS_UNDER_IPMP(ill) && !ipmp_ill_is_active(ill)) {
                /*
                 * need_refrele implies that the under ill was selected by
                 * ipmp_ill_hold_xmit_ill() because either the in_ill was an
                 * ipmp_ill, or we are sending a non-unicast packet on an
                 * under_ill. However, when we get here, the ill selected by
                 * ipmp_ill_hold_xmit_ill was pulled out of the active set
                 * (for unicast) or cast_ill nomination (for !unicast) after
                 * it was picked as the outgoing ill.  We have to pick an
                 * active interface and/or cast_ill in the group.
                 */
                mutex_exit(&ill->ill_phyint->phyint_lock);
                nce_delete(nce);
                mutex_exit(&ill->ill_lock);
                rw_exit(&ill->ill_ipst->ips_ill_g_lock);
                nce_refrele(nce);
                ill_refrele(ill);
                if ((ill = ipmp_ill_hold_xmit_ill(in_ill, is_unicast)) == NULL)
                        return (NULL);
                goto retry;
        } else {
                mutex_exit(&ill->ill_phyint->phyint_lock);
                mutex_exit(&ill->ill_lock);
                rw_exit(&ill->ill_ipst->ips_ill_g_lock);
        }
done:
        ASSERT(nce->nce_ill == ill);
        if (need_refrele)
                ill_refrele(ill);
        return (nce);
}

nce_t *
arp_nce_init(ill_t *ill, in_addr_t addr4, int ire_type)
{
        return (ire_nce_init(ill, &addr4, ire_type));
}

nce_t *
ndp_nce_init(ill_t *ill, const in6_addr_t *addr6, int ire_type)
{
        ASSERT((ire_type & IRE_BROADCAST) == 0);
        return (ire_nce_init(ill, addr6, ire_type));
}

/*
 * The caller should hold irb_lock as a writer if the ire is in a bucket.
 * This routine will clear ire_nce_cache, and we make sure that we can never
 * set ire_nce_cache after the ire is marked condemned.
 */
void
ire_make_condemned(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;
        nce_t           *nce;

        mutex_enter(&ire->ire_lock);
        ASSERT(ire->ire_bucket == NULL ||
            RW_WRITE_HELD(&ire->ire_bucket->irb_lock));
        ASSERT(!IRE_IS_CONDEMNED(ire));
        ire->ire_generation = IRE_GENERATION_CONDEMNED;
        /* Count how many condemned ires for kmem_cache callback */
        atomic_inc_32(&ipst->ips_num_ire_condemned);
        nce = ire->ire_nce_cache;
        ire->ire_nce_cache = NULL;
        mutex_exit(&ire->ire_lock);
        if (nce != NULL)
                nce_refrele(nce);
}

/*
 * Increment the generation avoiding the special condemned value
 */
void
ire_increment_generation(ire_t *ire)
{
        uint_t generation;

        mutex_enter(&ire->ire_lock);
        /*
         * Even though the caller has a hold it can't prevent a concurrent
         * ire_delete marking the IRE condemned
         */
        if (!IRE_IS_CONDEMNED(ire)) {
                generation = ire->ire_generation + 1;
                if (generation == IRE_GENERATION_CONDEMNED)
                        generation = IRE_GENERATION_INITIAL;
                ASSERT(generation != IRE_GENERATION_VERIFY);
                ire->ire_generation = generation;
        }
        mutex_exit(&ire->ire_lock);
}

/*
 * Increment ire_generation on all the IRE_MULTICASTs
 * Used when the default multicast interface (as determined by
 * ill_lookup_multicast) might have changed.
 *
 * That includes the zoneid, IFF_ flags, the IPv6 scope of the address, and
 * ill unplumb.
 */
void
ire_increment_multicast_generation(ip_stack_t *ipst, boolean_t isv6)
{
        ill_t   *ill;
        ill_walk_context_t ctx;

        rw_enter(&ipst->ips_ill_g_lock, RW_READER);
        if (isv6)
                ill = ILL_START_WALK_V6(&ctx, ipst);
        else
                ill = ILL_START_WALK_V4(&ctx, ipst);
        for (; ill != NULL; ill = ill_next(&ctx, ill)) {
                if (ILL_IS_CONDEMNED(ill))
                        continue;
                if (ill->ill_ire_multicast != NULL)
                        ire_increment_generation(ill->ill_ire_multicast);
        }
        rw_exit(&ipst->ips_ill_g_lock);
}

/*
 * Return a held IRE_NOROUTE with RTF_REJECT set
 */
ire_t *
ire_reject(ip_stack_t *ipst, boolean_t isv6)
{
        ire_t *ire;

        if (isv6)
                ire = ipst->ips_ire_reject_v6;
        else
                ire = ipst->ips_ire_reject_v4;

        ASSERT(ire->ire_generation != IRE_GENERATION_CONDEMNED);
        ire_refhold(ire);
        return (ire);
}

/*
 * Return a held IRE_NOROUTE with RTF_BLACKHOLE set
 */
ire_t *
ire_blackhole(ip_stack_t *ipst, boolean_t isv6)
{
        ire_t *ire;

        if (isv6)
                ire = ipst->ips_ire_blackhole_v6;
        else
                ire = ipst->ips_ire_blackhole_v4;

        ASSERT(ire->ire_generation != IRE_GENERATION_CONDEMNED);
        ire_refhold(ire);
        return (ire);
}

/*
 * Return a held IRE_MULTICAST.
 */
ire_t *
ire_multicast(ill_t *ill)
{
        ire_t *ire = ill->ill_ire_multicast;

        ASSERT(ire == NULL || ire->ire_generation != IRE_GENERATION_CONDEMNED);
        if (ire == NULL)
                ire = ire_blackhole(ill->ill_ipst, ill->ill_isv6);
        else
                ire_refhold(ire);
        return (ire);
}

/*
 * Given an IRE return its nexthop IRE. The nexthop IRE is an IRE_ONLINK
 * that is an exact match (i.e., a /32 for IPv4 and /128 for IPv6).
 * This can return an RTF_REJECT|RTF_BLACKHOLE.
 * The returned IRE is held.
 * The assumption is that ip_select_route() has been called and returned the
 * IRE (thus ip_select_route would have set up the ire_dep* information.)
 * If some IRE is deleteted then ire_dep_remove() will have been called and
 * we might not find a nexthop IRE, in which case we return NULL.
 */
ire_t *
ire_nexthop(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;

        /* Acquire lock to walk ire_dep_parent */
        rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
        while (ire != NULL) {
                if (ire->ire_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
                        goto done;
                }
                /*
                 * If we find an IRE_ONLINK we are done. This includes
                 * the case of IRE_MULTICAST.
                 * Note that in order to send packets we need a host-specific
                 * IRE_IF_ALL first in the ire_dep_parent chain. Normally this
                 * is done by inserting an IRE_IF_CLONE if the IRE_INTERFACE
                 * was not host specific.
                 * However, ip_rts_request doesn't want to send packets
                 * hence doesn't want to allocate an IRE_IF_CLONE. Yet
                 * it needs an IRE_IF_ALL to get to the ill. Thus
                 * we return IRE_IF_ALL that are not host specific here.
                 */
                if (ire->ire_type & IRE_ONLINK)
                        goto done;
                ire = ire->ire_dep_parent;
        }
        rw_exit(&ipst->ips_ire_dep_lock);
        return (NULL);

done:
        ire_refhold(ire);
        rw_exit(&ipst->ips_ire_dep_lock);
        return (ire);
}

/*
 * Find the ill used to send packets. This will be NULL in case
 * of a reject or blackhole.
 * The returned ill is held; caller needs to do ill_refrele when done.
 */
ill_t *
ire_nexthop_ill(ire_t *ire)
{
        ill_t           *ill;

        ire = ire_nexthop(ire);
        if (ire == NULL)
                return (NULL);

        /* ire_ill can not change for an existing ire */
        ill = ire->ire_ill;
        if (ill != NULL)
                ill_refhold(ill);
        ire_refrele(ire);
        return (ill);
}

#ifdef DEBUG
static boolean_t
parent_has_child(ire_t *parent, ire_t *child)
{
        ire_t   *ire;
        ire_t   *prev;

        ire = parent->ire_dep_children;
        prev = NULL;
        while (ire != NULL) {
                if (prev == NULL) {
                        ASSERT(ire->ire_dep_sib_ptpn ==
                            &(parent->ire_dep_children));
                } else {
                        ASSERT(ire->ire_dep_sib_ptpn ==
                            &(prev->ire_dep_sib_next));
                }
                if (ire == child)
                        return (B_TRUE);
                prev = ire;
                ire = ire->ire_dep_sib_next;
        }
        return (B_FALSE);
}

static void
ire_dep_verify(ire_t *ire)
{
        ire_t           *parent = ire->ire_dep_parent;
        ire_t           *child = ire->ire_dep_children;

        ASSERT(ire->ire_ipversion == IPV4_VERSION ||
            ire->ire_ipversion == IPV6_VERSION);
        if (parent != NULL) {
                ASSERT(parent->ire_ipversion == IPV4_VERSION ||
                    parent->ire_ipversion == IPV6_VERSION);
                ASSERT(parent->ire_refcnt >= 1);
                ASSERT(parent_has_child(parent, ire));
        }
        if (child != NULL) {
                ASSERT(child->ire_ipversion == IPV4_VERSION ||
                    child->ire_ipversion == IPV6_VERSION);
                ASSERT(child->ire_dep_parent == ire);
                ASSERT(child->ire_dep_sib_ptpn != NULL);
                ASSERT(parent_has_child(ire, child));
        }
}
#endif /* DEBUG */

/*
 * Assumes ire_dep_parent is set. Remove this child from its parent's linkage.
 */
void
ire_dep_remove(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;
        ire_t           *parent = ire->ire_dep_parent;
        ire_t           *next;
        nce_t           *nce;

        ASSERT(RW_WRITE_HELD(&ipst->ips_ire_dep_lock));
        ASSERT(ire->ire_dep_parent != NULL);
        ASSERT(ire->ire_dep_sib_ptpn != NULL);

#ifdef DEBUG
        ire_dep_verify(ire);
        ire_dep_verify(parent);
#endif

        next = ire->ire_dep_sib_next;
        if (next != NULL)
                next->ire_dep_sib_ptpn = ire->ire_dep_sib_ptpn;

        ASSERT(*(ire->ire_dep_sib_ptpn) == ire);
        *(ire->ire_dep_sib_ptpn) = ire->ire_dep_sib_next;

        ire->ire_dep_sib_ptpn = NULL;
        ire->ire_dep_sib_next = NULL;

        mutex_enter(&ire->ire_lock);
        parent = ire->ire_dep_parent;
        ire->ire_dep_parent = NULL;
        mutex_exit(&ire->ire_lock);

        /*
         * Make sure all our children, grandchildren, etc set
         * ire_dep_parent_generation to IRE_GENERATION_VERIFY since
         * we can no longer guarantee than the children have a current
         * ire_nce_cache and ire_nexthop_ill().
         */
        if (ire->ire_dep_children != NULL)
                ire_dep_invalidate_children(ire->ire_dep_children);

        /*
         * Since the parent is gone we make sure we clear ire_nce_cache.
         * We can clear it under ire_lock even if the IRE is used
         */
        mutex_enter(&ire->ire_lock);
        nce = ire->ire_nce_cache;
        ire->ire_nce_cache = NULL;
        mutex_exit(&ire->ire_lock);
        if (nce != NULL)
                nce_refrele(nce);

#ifdef DEBUG
        ire_dep_verify(ire);
        ire_dep_verify(parent);
#endif

        ire_refrele_notr(parent);
        ire_refrele_notr(ire);
}

/*
 * Insert the child in the linkage of the parent
 */
static void
ire_dep_parent_insert(ire_t *child, ire_t *parent)
{
        ip_stack_t      *ipst = child->ire_ipst;
        ire_t           *next;

        ASSERT(RW_WRITE_HELD(&ipst->ips_ire_dep_lock));
        ASSERT(child->ire_dep_parent == NULL);

#ifdef DEBUG
        ire_dep_verify(child);
        ire_dep_verify(parent);
#endif
        /* No parents => no siblings */
        ASSERT(child->ire_dep_sib_ptpn == NULL);
        ASSERT(child->ire_dep_sib_next == NULL);

        ire_refhold_notr(parent);
        ire_refhold_notr(child);

        /* Head insertion */
        next = parent->ire_dep_children;
        if (next != NULL) {
                ASSERT(next->ire_dep_sib_ptpn == &(parent->ire_dep_children));
                child->ire_dep_sib_next = next;
                next->ire_dep_sib_ptpn = &(child->ire_dep_sib_next);
        }
        parent->ire_dep_children = child;
        child->ire_dep_sib_ptpn = &(parent->ire_dep_children);

        mutex_enter(&child->ire_lock);
        child->ire_dep_parent = parent;
        mutex_exit(&child->ire_lock);

#ifdef DEBUG
        ire_dep_verify(child);
        ire_dep_verify(parent);
#endif
}


/*
 * Given count worth of ires and generations, build ire_dep_* relationships
 * from ires[0] to ires[count-1]. Record generations[i+1] in
 * ire_dep_parent_generation for ires[i].
 * We graft onto an existing parent chain by making sure that we don't
 * touch ire_dep_parent for ires[count-1].
 *
 * We check for any condemned ire_generation count and return B_FALSE in
 * that case so that the caller can tear it apart.
 *
 * Note that generations[0] is not used. Caller handles that.
 */
boolean_t
ire_dep_build(ire_t *ires[], uint_t generations[], uint_t count)
{
        ire_t           *ire = ires[0];
        ip_stack_t      *ipst;
        uint_t          i;

        ASSERT(count > 0);
        if (count == 1) {
                /* No work to do */
                return (B_TRUE);
        }
        ipst = ire->ire_ipst;
        rw_enter(&ipst->ips_ire_dep_lock, RW_WRITER);
        /*
         * Do not remove the linkage for any existing parent chain i.e.,
         * ires[count-1] is left alone.
         */
        for (i = 0; i < count-1; i++) {
                /* Remove existing parent if we need to change it */
                if (ires[i]->ire_dep_parent != NULL &&
                    ires[i]->ire_dep_parent != ires[i+1])
                        ire_dep_remove(ires[i]);
        }

        for (i = 0; i < count - 1; i++) {
                ASSERT(ires[i]->ire_ipversion == IPV4_VERSION ||
                    ires[i]->ire_ipversion == IPV6_VERSION);
                /* Does it need to change? */
                if (ires[i]->ire_dep_parent != ires[i+1])
                        ire_dep_parent_insert(ires[i], ires[i+1]);

                mutex_enter(&ires[i+1]->ire_lock);
                if (IRE_IS_CONDEMNED(ires[i+1])) {
                        mutex_exit(&ires[i+1]->ire_lock);
                        rw_exit(&ipst->ips_ire_dep_lock);
                        return (B_FALSE);
                }
                mutex_exit(&ires[i+1]->ire_lock);

                mutex_enter(&ires[i]->ire_lock);
                ires[i]->ire_dep_parent_generation = generations[i+1];
                mutex_exit(&ires[i]->ire_lock);
        }
        rw_exit(&ipst->ips_ire_dep_lock);
        return (B_TRUE);
}

/*
 * Given count worth of ires, unbuild ire_dep_* relationships
 * from ires[0] to ires[count-1].
 */
void
ire_dep_unbuild(ire_t *ires[], uint_t count)
{
        ip_stack_t      *ipst;
        uint_t          i;

        if (count == 0) {
                /* No work to do */
                return;
        }
        ipst = ires[0]->ire_ipst;
        rw_enter(&ipst->ips_ire_dep_lock, RW_WRITER);
        for (i = 0; i < count; i++) {
                ASSERT(ires[i]->ire_ipversion == IPV4_VERSION ||
                    ires[i]->ire_ipversion == IPV6_VERSION);
                if (ires[i]->ire_dep_parent != NULL)
                        ire_dep_remove(ires[i]);
                mutex_enter(&ires[i]->ire_lock);
                ires[i]->ire_dep_parent_generation = IRE_GENERATION_VERIFY;
                mutex_exit(&ires[i]->ire_lock);
        }
        rw_exit(&ipst->ips_ire_dep_lock);
}

/*
 * Both the forwarding and the outbound code paths can trip on
 * a condemned NCE, in which case we call this function.
 * We have two different behaviors: if the NCE was UNREACHABLE
 * it is an indication that something failed. In that case
 * we see if we should look for a different IRE (for example,
 * delete any matching redirect IRE, or try a different
 * IRE_DEFAULT (ECMP)). We mark the ire as bad so a hopefully
 * different IRE will be picked next time we send/forward.
 *
 * If we are called by the output path then fail_if_better is set
 * and we return NULL if there could be a better IRE. This is because the
 * output path retries the IRE lookup. (The input/forward path can not retry.)
 *
 * If the NCE was not unreachable then we pick/allocate a
 * new (most likely ND_INITIAL) NCE and proceed with it.
 *
 * ipha/ip6h are needed for multicast packets; ipha needs to be
 * set for IPv4 and ip6h needs to be set for IPv6 packets.
 */
nce_t *
ire_handle_condemned_nce(nce_t *nce, ire_t *ire, ipha_t *ipha, ip6_t *ip6h,
    boolean_t fail_if_better)
{
        if (nce->nce_common->ncec_state == ND_UNREACHABLE) {
                if (ire_no_good(ire) && fail_if_better) {
                        /*
                         * Did some changes, or ECMP likely to exist.
                         * Make ip_output look for a different IRE
                         */
                        return (NULL);
                }
        }
        if (ire_revalidate_nce(ire) == ENETUNREACH) {
                /* The ire_dep_parent chain went bad, or no memory? */
                (void) ire_no_good(ire);
                return (NULL);
        }
        if (ire->ire_ipversion == IPV4_VERSION) {
                ASSERT(ipha != NULL);
                nce = ire_to_nce(ire, ipha->ipha_dst, NULL);
        } else {
                ASSERT(ip6h != NULL);
                nce = ire_to_nce(ire, INADDR_ANY, &ip6h->ip6_dst);
        }

        if (nce == NULL)
                return (NULL);
        if (nce->nce_is_condemned) {
                nce_refrele(nce);
                return (NULL);
        }
        return (nce);
}

/*
 * The caller has found that the ire is bad due to a reference to an NCE in
 * ND_UNREACHABLE state.  We update things so a subsequent attempt to send
 * to the destination is likely to find different IRE, or that a new NCE
 * would be created.
 *
 * Returns B_TRUE if it is likely that a subsequent ire_ftable_lookup would
 * find a different route (either due to having deleted a redirect, or there
 * being ECMP routes.)
 *
 * If we have a redirect (RTF_DYNAMIC) we delete it.
 * Otherwise we increment ire_badcnt and increment the generation number so
 * that a cached ixa_ire will redo the route selection. ire_badcnt is taken
 * into account in the route selection when we have multiple choices (multiple
 * default routes or ECMP in general).
 * Any time ip_select_route find an ire with a condemned ire_nce_cache
 * (e.g., if no equal cost route to the bad one) ip_select_route will make
 * sure the NCE is revalidated to avoid getting stuck on a
 * NCE_F_CONDMNED ncec that caused ire_no_good to be called.
 */
boolean_t
ire_no_good(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;
        ire_t           *ire2;
        nce_t           *nce;

        if (ire->ire_flags & RTF_DYNAMIC) {
                ire_delete(ire);
                return (B_TRUE);
        }
        if (ire->ire_flags & RTF_INDIRECT) {
                /* Check if next IRE is a redirect */
                rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
                if (ire->ire_dep_parent != NULL &&
                    (ire->ire_dep_parent->ire_flags & RTF_DYNAMIC)) {
                        ire2 = ire->ire_dep_parent;
                        ire_refhold(ire2);
                } else {
                        ire2 = NULL;
                }
                rw_exit(&ipst->ips_ire_dep_lock);
                if (ire2 != NULL) {
                        ire_delete(ire2);
                        ire_refrele(ire2);
                        return (B_TRUE);
                }
        }
        /*
         * No redirect involved. Increment badcnt so that if we have ECMP
         * routes we are likely to pick a different one for the next packet.
         *
         * If the NCE is unreachable and condemned we should drop the reference
         * to it so that a new NCE can be created.
         *
         * Finally we increment the generation number so that any ixa_ire
         * cache will be revalidated.
         */
        mutex_enter(&ire->ire_lock);
        ire->ire_badcnt++;
        ire->ire_last_badcnt = TICK_TO_SEC(ddi_get_lbolt64());
        nce = ire->ire_nce_cache;
        if (nce != NULL && nce->nce_is_condemned &&
            nce->nce_common->ncec_state == ND_UNREACHABLE)
                ire->ire_nce_cache = NULL;
        else
                nce = NULL;
        mutex_exit(&ire->ire_lock);
        if (nce != NULL)
                nce_refrele(nce);

        ire_increment_generation(ire);
        ire_dep_incr_generation(ire);

        return (ire->ire_bucket->irb_ire_cnt > 1);
}

/*
 * Walk ire_dep_parent chain and validate that ire_dep_parent->ire_generation ==
 * ire_dep_parent_generation.
 * If they all match we just return ire_generation from the topmost IRE.
 * Otherwise we propagate the mismatch by setting all ire_dep_parent_generation
 * above the mismatch to IRE_GENERATION_VERIFY and also returning
 * IRE_GENERATION_VERIFY.
 */
uint_t
ire_dep_validate_generations(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;
        uint_t          generation;
        ire_t           *ire1;

        rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
        generation = ire->ire_generation;       /* Assuming things match */
        for (ire1 = ire; ire1 != NULL; ire1 = ire1->ire_dep_parent) {
                ASSERT(ire1->ire_ipversion == IPV4_VERSION ||
                    ire1->ire_ipversion == IPV6_VERSION);
                if (ire1->ire_dep_parent == NULL)
                        break;
                if (ire1->ire_dep_parent_generation !=
                    ire1->ire_dep_parent->ire_generation)
                        goto mismatch;
        }
        rw_exit(&ipst->ips_ire_dep_lock);
        return (generation);

mismatch:
        generation = IRE_GENERATION_VERIFY;
        /* Fill from top down to the mismatch with _VERIFY */
        while (ire != ire1) {
                ASSERT(ire->ire_ipversion == IPV4_VERSION ||
                    ire->ire_ipversion == IPV6_VERSION);
                mutex_enter(&ire->ire_lock);
                ire->ire_dep_parent_generation = IRE_GENERATION_VERIFY;
                mutex_exit(&ire->ire_lock);
                ire = ire->ire_dep_parent;
        }
        rw_exit(&ipst->ips_ire_dep_lock);
        return (generation);
}

/*
 * Used when we need to return an ire with ire_dep_parent, but we
 * know the chain is invalid for instance we didn't create an IRE_IF_CLONE
 * Using IRE_GENERATION_VERIFY means that next time we'll redo the
 * recursive lookup.
 */
void
ire_dep_invalidate_generations(ire_t *ire)
{
        ip_stack_t      *ipst = ire->ire_ipst;

        rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
        while (ire != NULL) {
                ASSERT(ire->ire_ipversion == IPV4_VERSION ||
                    ire->ire_ipversion == IPV6_VERSION);
                mutex_enter(&ire->ire_lock);
                ire->ire_dep_parent_generation = IRE_GENERATION_VERIFY;
                mutex_exit(&ire->ire_lock);
                ire = ire->ire_dep_parent;
        }
        rw_exit(&ipst->ips_ire_dep_lock);
}

/* Set _VERIFY ire_dep_parent_generation for all children recursively */
static void
ire_dep_invalidate_children(ire_t *child)
{
        ip_stack_t      *ipst = child->ire_ipst;

        ASSERT(RW_WRITE_HELD(&ipst->ips_ire_dep_lock));
        /* Depth first */
        if (child->ire_dep_children != NULL)
                ire_dep_invalidate_children(child->ire_dep_children);

        while (child != NULL) {
                mutex_enter(&child->ire_lock);
                child->ire_dep_parent_generation = IRE_GENERATION_VERIFY;
                mutex_exit(&child->ire_lock);
                child = child->ire_dep_sib_next;
        }
}

static void
ire_dep_increment_children(ire_t *child)
{
        ip_stack_t      *ipst = child->ire_ipst;

        ASSERT(RW_READ_HELD(&ipst->ips_ire_dep_lock));
        /* Depth first */
        if (child->ire_dep_children != NULL)
                ire_dep_increment_children(child->ire_dep_children);

        while (child != NULL) {
                if (!IRE_IS_CONDEMNED(child))
                        ire_increment_generation(child);
                child = child->ire_dep_sib_next;
        }
}

/*
 * Walk all the children of this ire recursively and increment their
 * generation number.
 */
static void
ire_dep_incr_generation_locked(ire_t *parent)
{
        ASSERT(RW_READ_HELD(&parent->ire_ipst->ips_ire_dep_lock));
        if (parent->ire_dep_children != NULL)
                ire_dep_increment_children(parent->ire_dep_children);
}

void
ire_dep_incr_generation(ire_t *parent)
{
        ip_stack_t      *ipst = parent->ire_ipst;

        rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
        ire_dep_incr_generation_locked(parent);
        rw_exit(&ipst->ips_ire_dep_lock);
}

/*
 * Get a new ire_nce_cache for this IRE as well as its nexthop.
 * Returns zero if it succeeds. Can fail due to lack of memory or when
 * the route has become unreachable. Returns ENOMEM and ENETUNREACH in those
 * cases.
 *
 * In the in.mpathd case, the ire will have ire_testhidden
 * set; so we should create the ncec for the underlying ill.
 *
 * Note that the error returned by ire_revalidate_nce() is ignored by most
 * callers except ire_handle_condemned_nce(), which handles the ENETUNREACH
 * error to mark potentially bad ire's. For all the other callers, an
 * error return could indicate a transient condition like ENOMEM, or could
 * be the result of an interface that is going down/unplumbing. In the former
 * case (transient error), we would leave the old stale ire/ire_nce_cache
 * in place, and possibly use incorrect link-layer information to send packets
 * but would eventually recover. In the latter case (ill down/replumb),
 * ire_revalidate_nce() might return a condemned nce back, but we would then
 * recover in the packet output path.
 */
int
ire_revalidate_nce(ire_t *ire)
{
        nce_t           *nce, *old_nce;
        ire_t           *nexthop;

        /*
         * For multicast we conceptually have an NCE but we don't store it
         * in ire_nce_cache; when ire_to_nce is called we allocate the nce.
         */
        if (ire->ire_type & IRE_MULTICAST)
                return (0);

        /* ire_testhidden should only be set on under-interfaces */
        ASSERT(!ire->ire_testhidden || !IS_IPMP(ire->ire_ill));

        nexthop = ire_nexthop(ire);
        if (nexthop == NULL) {
                /* The route is potentially bad */
                (void) ire_no_good(ire);
                return (ENETUNREACH);
        }
        if (ire->ire_type & (IRE_LOCAL|IRE_LOOPBACK)) {
                ASSERT(ire->ire_ill != NULL);

                if (ire->ire_ipversion == IPV4_VERSION)
                        nce = nce_lookup_v4(ire->ire_ill, &ire->ire_addr);
                else
                        nce = nce_lookup_v6(ire->ire_ill, &ire->ire_addr_v6);
        } else {
                ASSERT(nexthop->ire_type & IRE_ONLINK);
                if (ire->ire_ipversion == IPV4_VERSION) {
                        nce = arp_nce_init(nexthop->ire_ill, nexthop->ire_addr,
                            nexthop->ire_type);
                } else {
                        nce = ndp_nce_init(nexthop->ire_ill,
                            &nexthop->ire_addr_v6, nexthop->ire_type);
                }
        }
        if (nce == NULL) {
                /*
                 * Leave the old stale one in place to avoid a NULL
                 * ire_nce_cache.
                 */
                ire_refrele(nexthop);
                return (ENOMEM);
        }

        if (nexthop != ire) {
                /* Update the nexthop ire */
                mutex_enter(&nexthop->ire_lock);
                old_nce = nexthop->ire_nce_cache;
                if (!IRE_IS_CONDEMNED(nexthop)) {
                        nce_refhold(nce);
                        nexthop->ire_nce_cache = nce;
                } else {
                        nexthop->ire_nce_cache = NULL;
                }
                mutex_exit(&nexthop->ire_lock);
                if (old_nce != NULL)
                        nce_refrele(old_nce);
        }
        ire_refrele(nexthop);

        mutex_enter(&ire->ire_lock);
        old_nce = ire->ire_nce_cache;
        if (!IRE_IS_CONDEMNED(ire)) {
                nce_refhold(nce);
                ire->ire_nce_cache = nce;
        } else {
                ire->ire_nce_cache = NULL;
        }
        mutex_exit(&ire->ire_lock);
        if (old_nce != NULL)
                nce_refrele(old_nce);

        nce_refrele(nce);
        return (0);
}

/*
 * Get a held nce for a given ire.
 * In the common case this is just from ire_nce_cache.
 * For IRE_MULTICAST this needs to do an explicit lookup since we do not
 * have an IRE_MULTICAST per address.
 * Note that this explicitly returns CONDEMNED NCEs. The caller needs those
 * so they can check whether the NCE went unreachable (as opposed to was
 * condemned for some other reason).
 */
nce_t *
ire_to_nce(ire_t *ire, ipaddr_t v4nexthop, const in6_addr_t *v6nexthop)
{
        nce_t   *nce;

        if (ire->ire_flags & (RTF_REJECT|RTF_BLACKHOLE))
                return (NULL);

        /* ire_testhidden should only be set on under-interfaces */
        ASSERT(!ire->ire_testhidden || !IS_IPMP(ire->ire_ill));

        mutex_enter(&ire->ire_lock);
        nce = ire->ire_nce_cache;
        if (nce != NULL) {
                nce_refhold(nce);
                mutex_exit(&ire->ire_lock);
                return (nce);
        }
        mutex_exit(&ire->ire_lock);

        if (ire->ire_type & IRE_MULTICAST) {
                ASSERT(ire->ire_ill != NULL);

                if (ire->ire_ipversion == IPV4_VERSION) {
                        ASSERT(v6nexthop == NULL);

                        nce = arp_nce_init(ire->ire_ill, v4nexthop,
                            ire->ire_type);
                } else {
                        ASSERT(v6nexthop != NULL);
                        ASSERT(v4nexthop == 0);
                        nce = ndp_nce_init(ire->ire_ill, v6nexthop,
                            ire->ire_type);
                }
                return (nce);
        }
        return (NULL);
}

nce_t *
ire_to_nce_pkt(ire_t *ire, mblk_t *mp)
{
        ipha_t          *ipha;
        ip6_t           *ip6h;

        if (IPH_HDR_VERSION(mp->b_rptr) == IPV4_VERSION) {
                ipha = (ipha_t *)mp->b_rptr;
                return (ire_to_nce(ire, ipha->ipha_dst, NULL));
        } else {
                ip6h = (ip6_t *)mp->b_rptr;
                return (ire_to_nce(ire, INADDR_ANY, &ip6h->ip6_dst));
        }
}

/*
 * Given an IRE_INTERFACE (that matches more than one address) create
 * and return an IRE_IF_CLONE for the specific address.
 * Return the generation number.
 * Returns NULL is no memory for the IRE.
 * Handles both IPv4 and IPv6.
 *
 * IRE_IF_CLONE entries may only be created adn added by calling
 * ire_create_if_clone(), and we depend on the fact that ire_add will
 * atomically ensure that attempts to add multiple identical IRE_IF_CLONE
 * entries will not result in duplicate (i.e., ire_identical_ref > 1)
 * CLONE entries, so that a single ire_delete is sufficient to remove the
 * CLONE.
 */
ire_t *
ire_create_if_clone(ire_t *ire_if, const in6_addr_t *addr, uint_t *generationp)
{
        ire_t           *ire;
        ire_t           *nire;

        if (ire_if->ire_ipversion == IPV4_VERSION) {
                ipaddr_t        v4addr;
                ipaddr_t        mask = IP_HOST_MASK;

                ASSERT(IN6_IS_ADDR_V4MAPPED(addr));
                IN6_V4MAPPED_TO_IPADDR(addr, v4addr);

                ire = ire_create(
                    (uchar_t *)&v4addr,                 /* dest address */
                    (uchar_t *)&mask,                   /* mask */
                    (uchar_t *)&ire_if->ire_gateway_addr,
                    IRE_IF_CLONE,                       /* IRE type */
                    ire_if->ire_ill,
                    ire_if->ire_zoneid,
                    ire_if->ire_flags | RTF_HOST,
                    ire_if->ire_ipst);
        } else {
                ASSERT(!IN6_IS_ADDR_V4MAPPED(addr));
                ire = ire_create_v6(
                    addr,                               /* dest address */
                    &ipv6_all_ones,                     /* mask */
                    &ire_if->ire_gateway_addr_v6,       /* gateway addr */
                    IRE_IF_CLONE,                       /* IRE type */
                    ire_if->ire_ill,
                    ire_if->ire_zoneid,
                    ire_if->ire_flags | RTF_HOST,
                    ire_if->ire_ipst);
        }
        if (ire == NULL)
                return (NULL);

        /* Take the metrics, in particular the mtu, from the IRE_IF */
        ire->ire_metrics = ire_if->ire_metrics;

        nire = ire_add(ire);
        if (nire == NULL) /* Some failure */
                return (NULL);

        if (generationp != NULL)
                *generationp = nire->ire_generation;

        return (nire);
}

/*
 * The argument is an IRE_INTERFACE. Delete all of IRE_IF_CLONE in the
 * ire_dep_children (just walk the ire_dep_sib_next since they are all
 * immediate children.)
 * Since we hold a lock while we remove them we need to defer the actual
 * calls to ire_delete() until we have dropped the lock. This makes things
 * less efficient since we restart at the top after dropping the lock. But
 * we only run when an IRE_INTERFACE is deleted which is infrquent.
 *
 * Note that ire_dep_children can be any mixture of offlink routes and
 * IRE_IF_CLONE entries.
 */
void
ire_dep_delete_if_clone(ire_t *parent)
{
        ip_stack_t      *ipst = parent->ire_ipst;
        ire_t           *child, *next;

restart:
        rw_enter(&ipst->ips_ire_dep_lock, RW_READER);
        if (parent->ire_dep_children == NULL) {
                rw_exit(&ipst->ips_ire_dep_lock);
                return;
        }
        child = parent->ire_dep_children;
        while (child != NULL) {
                next = child->ire_dep_sib_next;
                if ((child->ire_type & IRE_IF_CLONE) &&
                    !IRE_IS_CONDEMNED(child)) {
                        ire_refhold(child);
                        rw_exit(&ipst->ips_ire_dep_lock);
                        ire_delete(child);
                        ASSERT(IRE_IS_CONDEMNED(child));
                        ire_refrele(child);
                        goto restart;
                }
                child = next;
        }
        rw_exit(&ipst->ips_ire_dep_lock);
}

/*
 * In the preferred/strict src multihoming modes, unbound routes (i.e.,
 * ire_t entries with ire_unbound set to B_TRUE) are bound to an interface
 * by selecting the first available interface that has an interface route for
 * the ire_gateway. If that interface is subsequently brought down, ill_downi()
 * will call ire_rebind() so that the unbound route can be bound to some other
 * matching interface thereby preserving the intended reachability information
 * from the original unbound route.
 */
void
ire_rebind(ire_t *ire)
{
        ire_t   *gw_ire, *new_ire;
        int     match_flags = MATCH_IRE_TYPE;
        ill_t   *gw_ill;
        boolean_t isv6 = (ire->ire_ipversion == IPV6_VERSION);
        ip_stack_t *ipst = ire->ire_ipst;

        ASSERT(ire->ire_unbound);
again:
        if (isv6) {
                gw_ire = ire_ftable_lookup_v6(&ire->ire_gateway_addr_v6, 0, 0,
                    IRE_INTERFACE, NULL, ALL_ZONES, match_flags, 0, ipst,
                    NULL);
        } else {
                gw_ire = ire_ftable_lookup_v4(ire->ire_gateway_addr, 0, 0,
                    IRE_INTERFACE, NULL, ALL_ZONES, match_flags, 0, ipst,
                    NULL);
        }
        if (gw_ire == NULL) {
                /* see comments in ip_rt_add[_v6]() for IPMP */
                if (match_flags & MATCH_IRE_TESTHIDDEN)
                        return;

                match_flags |= MATCH_IRE_TESTHIDDEN;
                goto again;
        }
        gw_ill = gw_ire->ire_ill;
        if (isv6) {
                new_ire = ire_create_v6(&ire->ire_addr_v6, &ire->ire_mask_v6,
                    &ire->ire_gateway_addr_v6, ire->ire_type, gw_ill,
                    ire->ire_zoneid, ire->ire_flags, ipst);
        } else {
                new_ire = ire_create((uchar_t *)&ire->ire_addr,
                    (uchar_t *)&ire->ire_mask,
                    (uchar_t *)&ire->ire_gateway_addr, ire->ire_type, gw_ill,
                    ire->ire_zoneid, ire->ire_flags, ipst);
        }
        ire_refrele(gw_ire);
        if (new_ire == NULL)
                return;
        new_ire->ire_unbound = B_TRUE;
        new_ire = ire_add(new_ire);
        if (new_ire != NULL)
                ire_refrele(new_ire);
}