inet/ip/ip_ire.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/* Copyright (c) 1990 Mentat Inc. */

#pragma ident	"%Z%%M%	%I%	%E% SMI"


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

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/strlog.h>
#include <sys/dlpi.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_rts.h>
#include <inet/nd.h>

#include <net/pfkeyv2.h>
#include <inet/ipsec_info.h>
#include <inet/sadb.h>
#include <sys/kmem.h>
#include <inet/tcp.h>
#include <inet/ipclassifier.h>
#include <sys/zone.h>

/*
 * Synchronization notes:
 *
 * The fields of the ire_t struct are protected in the following way :
 *
 * ire_next/ire_ptpn
 *
 *	- bucket lock of the respective tables (cache or forwarding tables).
 *
 * ire_fp_mp
 * ire_dlureq_mp
 *
 *	- ire_lock protects multiple threads updating ire_fp_mp
 *	  simultaneously. Otherwise no locks are used while accessing
 *	  (both read/write) both the fields.
 *
 * ire_mp, ire_rfq, ire_stq, ire_u *except* ire_gateway_addr[v6], ire_mask,
 * ire_type, ire_create_time, ire_masklen, ire_ipversion, ire_flags, ire_ipif,
 * ire_ihandle, ire_phandle, ire_nce, ire_bucket, ire_in_ill, ire_in_src_addr
 *
 *	- 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_v4/ire_add_v6 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_ident, ire_refcnt
 *
 *	- 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_max_frag, ire_frag_flag
 *
 *	- ire_lock is used to set/read both of them together.
 *
 * ire_tire_mark
 *
 *	- Set in ire_create and updated in ire_expire, which is called
 *	  by only one function namely ip_trash_timer_expire. Thus only
 *	  one function updates and examines the value.
 *
 * ire_marks
 *	- bucket lock protects this.
 *
 * ire_ipsec_overhead/ire_ll_hdr_length
 *
 *	- Place holder for returning the information to the upper layers
 *	  when IRE_DB_REQ comes down.
 *
 * ip_ire_default_count protected by the bucket lock of
 * ip_forwarding_table[0][0].
 *
 * ipv6_ire_default_count is protected by the bucket lock of
 * ip_forwarding_table_v6[0][0].
 *
 * ip_ire_default_index/ipv6_ire_default_index is not protected as it
 * is just a hint at which default gateway to use. There is nothing
 * wrong in using the same gateway for two different connections.
 *
 * 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 separate cache table and forwarding table for IPv4 and IPv6.
 * Cache table (ip_cache_table/ip_cache_table_v6) is a pointer to an
 * array of irb_t structure and forwarding table (ip_forwarding_table/
 * ip_forwarding_table_v6) is an array of pointers to array of irb_t
 * structure. ip_forwarding_table[_v6] is allocated dynamically in
 * ire_add_v4/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[i]
 * or ip_forwarding_table_v6[i] without any locks.
 *
 * 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 macro IRB_REFHOLD macro. The flags irb_flags can be
 * set to IRE_MARK_CONDEMNED indicating that there are some ires
 * in this bucket that are marked with IRE_MARK_CONDEMNED and the
 * last thread to leave the bucket should delete the ires. Usually
 * this is done by the IRB_REFRELE macro which is used to decrement
 * the reference count on a bucket.
 *
 * IRE_REFHOLD/IRE_REFRELE macros operate on the ire which increments/
 * decrements the reference count, ire_refcnt, atomically on the ire.
 * ire_refcnt is modified only using this macro. 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_v4/ire_add_v6 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
 * macro. 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_lookup_local[_v6], ire_ctable_lookup[_v6], ire_ftable_lookup[_v6],
 * ire_cache_lookup[_v6], ire_lookup_multi[_v6], ire_route_lookup[_v6],
 * ipif_to_ire[_v6], ire_mrtun_lookup, ire_srcif_table_lookup.
 *
 * 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 macro. 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.
 *
 * NOTE : The only functions that does the IRE_REFRELE when an ire is
 *	  passed as an argument are :
 *
 *	  1) ip_wput_ire : This is because it IRE_REFHOLD/RELEs the
 *			   broadcast ires it looks up internally within
 *			   the function. Currently, for simplicity it does
 *			   not differentiate the one that is passed in and
 *			   the ones it looks up internally. It always
 *			   IRE_REFRELEs.
 *	  2) ire_send
 *	     ire_send_v6 : As ire_send calls ip_wput_ire and other functions
 *			   that take ire as an argument, it has to selectively
 *			   IRE_REFRELE the ire. To maintain symmetry,
 *			   ire_send_v6 does the same.
 *
 * Otherwise, 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_MARK_CONDEMNED signifies that the ire has been logically deleted and is
 * to be ignored when walking the ires using ire_next.
 *
 * IRE_MARK_HIDDEN signifies that the ire is a special ire typically for the
 * benefit of in.mpathd which needs to probe interfaces for failures. Normal
 * applications should not be seeing this ire and hence this ire is ignored
 * in most cases in the search 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().
 */

static irb_t *ip_forwarding_table[IP_MASK_TABLE_SIZE];
/* This is dynamically allocated in ip_ire_init */
static irb_t *ip_cache_table;
/* This is dynamically allocated in ire_add_mrtun */
irb_t	*ip_mrtun_table;

uint32_t	ire_handle = 1;
/*
 * ire_ft_init_lock is used while initializing ip_forwarding_table
 * dynamically in ire_add.
 */
kmutex_t	ire_ft_init_lock;
kmutex_t	ire_mrtun_lock;  /* Protects creation of table and it's count */
kmutex_t	ire_srcif_table_lock; /* Same as above */
/*
 * The following counts are used to determine whether a walk is
 * needed through the reverse tunnel table or through ills
 */
kmutex_t ire_handle_lock;	/* Protects ire_handle */
uint_t	ire_mrtun_count;	/* Number of ires in reverse tun table */

/*
 * A per-interface routing table is created ( if not present)
 * when the first entry is added to this special routing table.
 * This special routing table is accessed through the ill data structure.
 * The routing table looks like cache table. For example, currently it
 * is used by mobile-ip foreign agent to forward data that only comes from
 * the home agent tunnel for a mobile node. Thus if the outgoing interface
 * is a RESOLVER interface, IP may need to resolve the hardware address for
 * the outgoing interface. The routing entries in this table are not updated
 * in IRE_CACHE. When MCTL msg comes back from ARP, the incoming ill informa-
 * tion is lost as the write queue is passed to ip_wput.
 * But, before sending the packet out, the hardware information must be updated
 * in the special forwarding table. ire_srcif_table_count keeps track of total
 * number of ires that are in interface based tables. Each interface based
 * table hangs off of the incoming ill and each ill_t also keeps a refcnt
 * of ires in that table.
 */

uint_t	ire_srcif_table_count; /* Number of ires in all srcif tables */

/*
 * The minimum size of IRE cache table.  It will be recalcuated in
 * ip_ire_init().
 */
uint32_t ip_cache_table_size = IP_CACHE_TABLE_SIZE;
uint32_t ip6_cache_table_size = IP6_CACHE_TABLE_SIZE;

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

struct	kmem_cache	*ire_cache;
static ire_t	ire_null;

ire_stats_t ire_stats_v4;	/* IPv4 ire statistics */
ire_stats_t ire_stats_v6;	/* IPv6 ire statistics */

/*
 * The threshold number of IRE in a bucket when the IREs are
 * cleaned up.  This threshold is calculated later in ip_open()
 * based on the speed of CPU and available memory.  This default
 * value is the maximum.
 *
 * We have two kinds of cached IRE, temporary and
 * non-temporary.  Temporary IREs are marked with
 * IRE_MARK_TEMPORARY.  They are IREs created for non
 * TCP traffic and for forwarding purposes.  All others
 * are non-temporary IREs.  We don't mark IRE created for
 * TCP as temporary because TCP is stateful and there are
 * info stored in the IRE which can be shared by other TCP
 * connections to the same destination.  For connected
 * endpoint, we also don't want to mark the IRE used as
 * temporary because the same IRE will be used frequently,
 * otherwise, the app should not do a connect().  We change
 * the marking at ip_bind_connected_*() if necessary.
 *
 * We want to keep the cache IRE hash bucket length reasonably
 * short, otherwise IRE lookup functions will take "forever."
 * We use the "crude" function that the IRE bucket
 * length should be based on the CPU speed, which is 1 entry
 * per x MHz, depending on the shift factor ip_ire_cpu_ratio
 * (n).  This means that with a 750MHz CPU, the max bucket
 * length can be (750 >> n) entries.
 *
 * Note that this threshold is separate for temp and non-temp
 * IREs.  This means that the actual bucket length can be
 * twice as that.  And while we try to keep temporary IRE
 * length at most at the threshold value, we do not attempt to
 * make the length for non-temporary IREs fixed, for the
 * reason stated above.  Instead, we start trying to find
 * "unused" non-temporary IREs when the bucket length reaches
 * this threshold and clean them up.
 *
 * We also want to limit the amount of memory used by
 * IREs.  So if we are allowed to use ~3% of memory (M)
 * for those IREs, each bucket should not have more than
 *
 * 	M / num of cache bucket / sizeof (ire_t)
 *
 * Again the above memory uses are separate for temp and
 * non-temp cached IREs.
 *
 * We may also want the limit to be a function of the number
 * of interfaces and number of CPUs.  Doing the initialization
 * in ip_open() means that every time an interface is plumbed,
 * the max is re-calculated.  Right now, we don't do anything
 * different.  In future, when we have more experience, we
 * may want to change this behavior.
 */
uint32_t ip_ire_max_bucket_cnt = 10;
uint32_t ip6_ire_max_bucket_cnt = 10;

/*
 * The minimum of the temporary IRE bucket count.  We do not want
 * the length of each bucket to be too short.  This may hurt
 * performance of some apps as the temporary IREs are removed too
 * often.
 */
uint32_t ip_ire_min_bucket_cnt = 3;
uint32_t ip6_ire_min_bucket_cnt = 3;

/*
 * The ratio of memory consumed by IRE used for temporary to available
 * memory.  This is a shift factor, so 6 means the ratio 1 to 64.  This
 * value can be changed in /etc/system.  6 is a reasonable number.
 */
uint32_t ip_ire_mem_ratio = 6;
/* The shift factor for CPU speed to calculate the max IRE bucket length. */
uint32_t ip_ire_cpu_ratio = 7;

/*
 * The maximum number of buckets in IRE cache table.  In future, we may
 * want to make it a dynamic hash table.  For the moment, we fix the
 * size and allocate the table in ip_ire_init() when IP is first loaded.
 * We take into account the amount of memory a system has.
 */
#define	IP_MAX_CACHE_TABLE_SIZE	4096

static uint32_t	ip_max_cache_table_size = IP_MAX_CACHE_TABLE_SIZE;
static uint32_t	ip6_max_cache_table_size = IP_MAX_CACHE_TABLE_SIZE;

#define	NUM_ILLS	3	/* To build the ILL list to unlock */

/* Zero iulp_t for initialization. */
const iulp_t	ire_uinfo_null = { 0 };

static int	ire_add_v4(ire_t **ire_p, queue_t *q, mblk_t *mp,
    ipsq_func_t func);
static int	ire_add_srcif_v4(ire_t **ire_p, queue_t *q, mblk_t *mp,
    ipsq_func_t func);
static ire_t	*ire_update_srcif_v4(ire_t *ire);
static void	ire_delete_v4(ire_t *ire);
static void	ire_report_ftable(ire_t *ire, char *mp);
static void	ire_report_ctable(ire_t *ire, char *mp);
static void	ire_report_mrtun_table(ire_t *ire, char *mp);
static void	ire_report_srcif_table(ire_t *ire, char *mp);
static void	ire_walk_ipvers(pfv_t func, char *arg, uchar_t vers,
    zoneid_t zoneid);
static void	ire_walk_ill_ipvers(uint_t match_flags, uint_t ire_type,
		    pfv_t func, char *arg, uchar_t vers, ill_t *ill);
static	void	ire_walk_ill_tables(uint_t match_flags, uint_t ire_type,
		    pfv_t func, char *arg, size_t ftbl_sz, size_t htbl_sz,
		    irb_t **ipftbl, size_t ctbl_sz, irb_t *ipctbl, ill_t *ill,
		    zoneid_t zoneid);
static void	ire_delete_host_redirects(ipaddr_t gateway);
static boolean_t ire_match_args(ire_t *ire, ipaddr_t addr, ipaddr_t mask,
		    ipaddr_t gateway, int type, ipif_t *ipif, zoneid_t zoneid,
		    uint32_t ihandle, int match_flags);
static void	ire_cache_cleanup(irb_t *irb, uint32_t threshold, int cnt);
extern void	ill_unlock_ills(ill_t **list, int cnt);
static void	ire_fastpath_list_add(ill_t *ill, ire_t *ire);
extern void	th_trace_rrecord(th_trace_t *);
#ifdef IRE_DEBUG
static void	ire_trace_inactive(ire_t *);
#endif

/*
 * To avoid bloating the code, we call this function instead of
 * using the macro IRE_REFRELE. Use macro only in performance
 * critical paths.
 *
 * 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.
 */
void
ire_refrele(ire_t *ire)
{
	IRE_REFRELE(ire);
}

void
ire_refrele_notr(ire_t *ire)
{
	IRE_REFRELE_NOTR(ire);
}

/*
 * kmem_cache_alloc constructor for IRE in kma space.
 * Note that when ire_mp is set the IRE is stored in that mblk and
 * not in this cache.
 */
/* ARGSUSED */
static int
ip_ire_constructor(void *buf, void *cdrarg, int kmflags)
{
	ire_t	*ire = buf;

	ire->ire_fp_mp = NULL;
	ire->ire_dlureq_mp = NULL;

	return (0);
}

/* ARGSUSED1 */
static void
ip_ire_destructor(void *buf, void *cdrarg)
{
	ire_t	*ire = buf;

	ASSERT(ire->ire_fp_mp == NULL);
	ASSERT(ire->ire_dlureq_mp == NULL);
}

/*
 * This function is associated with the IP_IOC_IRE_ADVISE_NO_REPLY
 * IOCTL.  It is used by TCP (or other ULPs) to supply revised information
 * for an existing CACHED IRE.
 */
/* ARGSUSED */
int
ip_ire_advise(queue_t *q, mblk_t *mp, cred_t *ioc_cr)
{
	uchar_t	*addr_ucp;
	ipic_t	*ipic;
	ire_t	*ire;
	ipaddr_t	addr;
	in6_addr_t	v6addr;
	irb_t	*irb;
	zoneid_t	zoneid;

	ASSERT(q->q_next == NULL);
	zoneid = Q_TO_CONN(q)->conn_zoneid;

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

	ipic = (ipic_t *)mp->b_rptr;
	if (!(addr_ucp = mi_offset_param(mp, ipic->ipic_addr_offset,
	    ipic->ipic_addr_length))) {
		return (EINVAL);
	}
	if (!OK_32PTR(addr_ucp))
		return (EINVAL);
	switch (ipic->ipic_addr_length) {
	case IP_ADDR_LEN: {
		/* Extract the destination address. */
		addr = *(ipaddr_t *)addr_ucp;
		/* Find the corresponding IRE. */
		ire = ire_cache_lookup(addr, zoneid);
		break;
	}
	case IPV6_ADDR_LEN: {
		/* Extract the destination address. */
		v6addr = *(in6_addr_t *)addr_ucp;
		/* Find the corresponding IRE. */
		ire = ire_cache_lookup_v6(&v6addr, zoneid);
		break;
	}
	default:
		return (EINVAL);
	}

	if (ire == NULL)
		return (ENOENT);
	/*
	 * Update the round trip time estimate and/or the max frag size
	 * and/or the slow start threshold.
	 *
	 * We serialize multiple advises using ire_lock.
	 */
	mutex_enter(&ire->ire_lock);
	if (ipic->ipic_rtt) {
		/*
		 * If there is no old cached values, initialize them
		 * conservatively.  Set them to be (1.5 * new value).
		 */
		if (ire->ire_uinfo.iulp_rtt != 0) {
			ire->ire_uinfo.iulp_rtt = (ire->ire_uinfo.iulp_rtt +
			    ipic->ipic_rtt) >> 1;
		} else {
			ire->ire_uinfo.iulp_rtt = ipic->ipic_rtt +
			    (ipic->ipic_rtt >> 1);
		}
		if (ire->ire_uinfo.iulp_rtt_sd != 0) {
			ire->ire_uinfo.iulp_rtt_sd =
			    (ire->ire_uinfo.iulp_rtt_sd +
			    ipic->ipic_rtt_sd) >> 1;
		} else {
			ire->ire_uinfo.iulp_rtt_sd = ipic->ipic_rtt_sd +
			    (ipic->ipic_rtt_sd >> 1);
		}
	}
	if (ipic->ipic_max_frag)
		ire->ire_max_frag = MIN(ipic->ipic_max_frag, IP_MAXPACKET);
	if (ipic->ipic_ssthresh != 0) {
		if (ire->ire_uinfo.iulp_ssthresh != 0)
			ire->ire_uinfo.iulp_ssthresh =
			    (ipic->ipic_ssthresh +
			    ire->ire_uinfo.iulp_ssthresh) >> 1;
		else
			ire->ire_uinfo.iulp_ssthresh = ipic->ipic_ssthresh;
	}
	/*
	 * Don't need the ire_lock below this. ire_type does not change
	 * after initialization. ire_marks is protected by irb_lock.
	 */
	mutex_exit(&ire->ire_lock);

	if (ipic->ipic_ire_marks != 0 && ire->ire_type == IRE_CACHE) {
		/*
		 * Only increment the temporary IRE count if the original
		 * IRE is not already marked temporary.
		 */
		irb = ire->ire_bucket;
		rw_enter(&irb->irb_lock, RW_WRITER);
		if ((ipic->ipic_ire_marks & IRE_MARK_TEMPORARY) &&
		    !(ire->ire_marks & IRE_MARK_TEMPORARY)) {
			irb->irb_tmp_ire_cnt++;
		}
		ire->ire_marks |= ipic->ipic_ire_marks;
		rw_exit(&irb->irb_lock);
	}

	ire_refrele(ire);
	return (0);
}

/*
 * This function is associated with the IP_IOC_IRE_DELETE[_NO_REPLY]
 * IOCTL[s].  The NO_REPLY form is used by TCP to delete a route IRE
 * for a host that is not responding.  This will force an attempt to
 * establish a new route, if available.  Management processes may want
 * to use the version that generates a reply.
 *
 * This function does not support IPv6 since Neighbor Unreachability Detection
 * means that negative advise like this is useless.
 */
/* ARGSUSED */
int
ip_ire_delete(queue_t *q, mblk_t *mp, cred_t *ioc_cr)
{
	uchar_t	*addr_ucp;
	ipaddr_t	addr;
	ire_t	*ire;
	ipid_t	*ipid;
	boolean_t routing_sock_info = B_FALSE;	/* Sent info? */
	zoneid_t	zoneid;

	ASSERT(q->q_next == NULL);
	zoneid = Q_TO_CONN(q)->conn_zoneid;

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

	ipid = (ipid_t *)mp->b_rptr;

	/* Only actions on IRE_CACHEs are acceptable at present. */
	if (ipid->ipid_ire_type != IRE_CACHE)
		return (EINVAL);

	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 IP_ADDR_LEN:
		/* addr_ucp points at IP addr */
		break;
	case sizeof (sin_t): {
		sin_t	*sin;
		/*
		 * 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;
		break;
	}
	default:
		return (EINVAL);
	}
	/* Extract the destination address. */
	bcopy(addr_ucp, &addr, IP_ADDR_LEN);

	/* Try to find the CACHED IRE. */
	ire = ire_cache_lookup(addr, zoneid);

	/* Nail it. */
	if (ire) {
		/* Allow delete only on CACHE entries */
		if (ire->ire_type != IRE_CACHE) {
			ire_refrele(ire);
			return (EINVAL);
		}

		/*
		 * Verify that the IRE has been around for a while.
		 * This is to protect against transport protocols
		 * that are too eager in sending delete messages.
		 */
		if (gethrestime_sec() <
		    ire->ire_create_time + ip_ignore_delete_time) {
			ire_refrele(ire);
			return (EINVAL);
		}
		/*
		 * Now we have a potentially dead cache entry. We need
		 * to remove it.
		 * If this cache entry is generated from a default route,
		 * search the default list and mark it dead and some
		 * background process will try to activate it.
		 */
		if ((ire->ire_gateway_addr != 0) && (ire->ire_cmask == 0)) {
			/*
			 * Make sure that we pick a different
			 * IRE_DEFAULT next time.
			 * The ip_ire_default_count tracks the number of
			 * IRE_DEFAULT entries. However, the
			 * ip_forwarding_table[0] also contains
			 * interface routes thus the count can be zero.
			 */
			ire_t *gw_ire;
			irb_t *irb_ptr;
			irb_t *irb;

			if (((irb_ptr = ip_forwarding_table[0]) != NULL) &&
			    (irb = &irb_ptr[0])->irb_ire != NULL &&
			    ip_ire_default_count != 0) {
				uint_t index;

				/*
				 * We grab it as writer just to serialize
				 * multiple threads trying to bump up
				 * ip_ire_default_index.
				 */
				rw_enter(&irb->irb_lock, RW_WRITER);
				if ((gw_ire = irb->irb_ire) == NULL) {
					rw_exit(&irb->irb_lock);
					goto done;
				}
				index = ip_ire_default_index %
				    ip_ire_default_count;
				while (index-- && gw_ire->ire_next != NULL)
					gw_ire = gw_ire->ire_next;

				/* Skip past the potentially bad gateway */
				if (ire->ire_gateway_addr ==
				    gw_ire->ire_gateway_addr)
					ip_ire_default_index++;

				rw_exit(&irb->irb_lock);
		    }
		}
done:
		/* report the bad route to routing sockets */
		ip_rts_change(RTM_LOSING, ire->ire_addr, ire->ire_gateway_addr,
		    ire->ire_mask, ire->ire_src_addr, 0, 0, 0,
		    (RTA_DST | RTA_GATEWAY | RTA_NETMASK | RTA_IFA));
		routing_sock_info = B_TRUE;
		ire_delete(ire);
		ire_refrele(ire);
	}
	/* Also look for an IRE_HOST_REDIRECT and remove it if present */
	ire = ire_route_lookup(addr, 0, 0, IRE_HOST_REDIRECT, NULL, NULL,
	    ALL_ZONES, MATCH_IRE_TYPE);

	/* Nail it. */
	if (ire) {
		if (!routing_sock_info) {
			ip_rts_change(RTM_LOSING, ire->ire_addr,
			    ire->ire_gateway_addr, ire->ire_mask,
			    ire->ire_src_addr, 0, 0, 0,
			    (RTA_DST | RTA_GATEWAY | RTA_NETMASK | RTA_IFA));
		}
		ire_delete(ire);
		ire_refrele(ire);
	}
	return (0);
}

/*
 * Named Dispatch routine to produce a formatted report on all IREs.
 * This report is accessed by using the ndd utility to "get" ND variable
 * "ipv4_ire_status".
 */
/* ARGSUSED */
int
ip_ire_report(queue_t *q, mblk_t *mp, caddr_t arg, cred_t *ioc_cr)
{
	zoneid_t zoneid;

	(void) mi_mpprintf(mp,
	    "IRE      " MI_COL_HDRPAD_STR
	/*   01234567[89ABCDEF] */
	    "rfq      " MI_COL_HDRPAD_STR
	/*   01234567[89ABCDEF] */
	    "stq      " MI_COL_HDRPAD_STR
	/*   01234567[89ABCDEF] */
	    " zone "
	/*   12345 */
	    "addr            mask            "
	/*   123.123.123.123 123.123.123.123 */
	    "src             gateway         mxfrg rtt   rtt_sd ssthresh ref "
	/*   123.123.123.123 123.123.123.123 12345 12345 123456 12345678 123 */
	    "rtomax tstamp_ok wscale_ok ecn_ok pmtud_ok sack sendpipe "
	/*   123456 123456789 123456789 123456 12345678 1234 12345678 */
	    "recvpipe in/out/forward type");
	/*   12345678 in/out/forward xxxxxxxxxx */

	/*
	 * Because of the ndd constraint, at most we can have 64K buffer
	 * to put in all IRE info.  So to be more efficient, just
	 * allocate a 64K buffer here, assuming we need that large buffer.
	 * This should be OK as only root can do ndd /dev/ip.
	 */
	if ((mp->b_cont = allocb(ND_MAX_BUF_LEN, BPRI_HI)) == NULL) {
		/* The following may work even if we cannot get a large buf. */
		(void) mi_mpprintf(mp, "<< Out of buffer >>\n");
		return (0);
	}

	zoneid = Q_TO_CONN(q)->conn_zoneid;
	if (zoneid == GLOBAL_ZONEID)
		zoneid = ALL_ZONES;

	ire_walk_v4(ire_report_ftable, (char *)mp->b_cont, zoneid);
	ire_walk_v4(ire_report_ctable, (char *)mp->b_cont, zoneid);

	return (0);
}

/* ire_walk routine invoked for ip_ire_report for each IRE. */
static void
ire_report_ftable(ire_t *ire, char *mp)
{
	char	buf1[16];
	char	buf2[16];
	char	buf3[16];
	char	buf4[16];
	uint_t	fo_pkt_count;
	uint_t	ib_pkt_count;
	int	ref;
	uint_t	print_len, buf_len;

	if (ire->ire_type & IRE_CACHETABLE)
	    return;
	buf_len = ((mblk_t *)mp)->b_datap->db_lim - ((mblk_t *)mp)->b_wptr;
	if (buf_len <= 0)
		return;

	/* Number of active references of this ire */
	ref = ire->ire_refcnt;
	/* "inbound" to a non local address is a forward */
	ib_pkt_count = ire->ire_ib_pkt_count;
	fo_pkt_count = 0;
	if (!(ire->ire_type & (IRE_LOCAL|IRE_BROADCAST))) {
		fo_pkt_count = ib_pkt_count;
		ib_pkt_count = 0;
	}
	print_len = snprintf((char *)((mblk_t *)mp)->b_wptr, buf_len,
	    MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR "%5d "
	    "%s %s %s %s %05d %05ld %06ld %08d %03d %06d %09d %09d %06d %08d "
	    "%04d %08d %08d %d/%d/%d %s\n",
	    (void *)ire, (void *)ire->ire_rfq, (void *)ire->ire_stq,
	    (int)ire->ire_zoneid,
	    ip_dot_addr(ire->ire_addr, buf1), ip_dot_addr(ire->ire_mask, buf2),
	    ip_dot_addr(ire->ire_src_addr, buf3),
	    ip_dot_addr(ire->ire_gateway_addr, buf4),
	    ire->ire_max_frag, ire->ire_uinfo.iulp_rtt,
	    ire->ire_uinfo.iulp_rtt_sd,
	    ire->ire_uinfo.iulp_ssthresh, ref,
	    ire->ire_uinfo.iulp_rtomax,
	    (ire->ire_uinfo.iulp_tstamp_ok ? 1: 0),
	    (ire->ire_uinfo.iulp_wscale_ok ? 1: 0),
	    (ire->ire_uinfo.iulp_ecn_ok ? 1: 0),
	    (ire->ire_uinfo.iulp_pmtud_ok ? 1: 0),
	    ire->ire_uinfo.iulp_sack,
	    ire->ire_uinfo.iulp_spipe, ire->ire_uinfo.iulp_rpipe,
	    ib_pkt_count, ire->ire_ob_pkt_count, fo_pkt_count,
	    ip_nv_lookup(ire_nv_tbl, (int)ire->ire_type));
	if (print_len < buf_len) {
		((mblk_t *)mp)->b_wptr += print_len;
	} else {
		((mblk_t *)mp)->b_wptr += buf_len;
	}
}

/* ire_walk routine invoked for ip_ire_report for each cached IRE. */
static void
ire_report_ctable(ire_t *ire, char *mp)
{
	char	buf1[16];
	char	buf2[16];
	char	buf3[16];
	char	buf4[16];
	uint_t	fo_pkt_count;
	uint_t	ib_pkt_count;
	int	ref;
	uint_t	print_len, buf_len;

	if ((ire->ire_type & IRE_CACHETABLE) == 0)
	    return;
	buf_len = ((mblk_t *)mp)->b_datap->db_lim - ((mblk_t *)mp)->b_wptr;
	if (buf_len <= 0)
		return;

	/* Number of active references of this ire */
	ref = ire->ire_refcnt;
	/* "inbound" to a non local address is a forward */
	ib_pkt_count = ire->ire_ib_pkt_count;
	fo_pkt_count = 0;
	if (!(ire->ire_type & (IRE_LOCAL|IRE_BROADCAST))) {
		fo_pkt_count = ib_pkt_count;
		ib_pkt_count = 0;
	}
	print_len =  snprintf((char *)((mblk_t *)mp)->b_wptr, buf_len,
	    MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR "%5d "
	    "%s %s %s %s %05d %05ld %06ld %08d %03d %06d %09d %09d %06d %08d "
	    "%04d %08d %08d %d/%d/%d %s\n",
	    (void *)ire, (void *)ire->ire_rfq, (void *)ire->ire_stq,
	    (int)ire->ire_zoneid,
	    ip_dot_addr(ire->ire_addr, buf1), ip_dot_addr(ire->ire_mask, buf2),
	    ip_dot_addr(ire->ire_src_addr, buf3),
	    ip_dot_addr(ire->ire_gateway_addr, buf4),
	    ire->ire_max_frag, ire->ire_uinfo.iulp_rtt,
	    ire->ire_uinfo.iulp_rtt_sd, ire->ire_uinfo.iulp_ssthresh, ref,
	    ire->ire_uinfo.iulp_rtomax,
	    (ire->ire_uinfo.iulp_tstamp_ok ? 1: 0),
	    (ire->ire_uinfo.iulp_wscale_ok ? 1: 0),
	    (ire->ire_uinfo.iulp_ecn_ok ? 1: 0),
	    (ire->ire_uinfo.iulp_pmtud_ok ? 1: 0),
	    ire->ire_uinfo.iulp_sack,
	    ire->ire_uinfo.iulp_spipe, ire->ire_uinfo.iulp_rpipe,
	    ib_pkt_count, ire->ire_ob_pkt_count, fo_pkt_count,
	    ip_nv_lookup(ire_nv_tbl, (int)ire->ire_type));
	if (print_len < buf_len) {
		((mblk_t *)mp)->b_wptr += print_len;
	} else {
		((mblk_t *)mp)->b_wptr += buf_len;
	}
}

/* ARGSUSED */
int
ip_ire_report_mrtun(queue_t *q, mblk_t *mp, caddr_t arg, cred_t *ioc_cr)
{
	(void) mi_mpprintf(mp,
	"IRE      " MI_COL_HDRPAD_STR
	/*   01234567[89ABCDEF] */
	"stq      " MI_COL_HDRPAD_STR
	/*   01234567[89ABCDEF] */
	"in_ill    " MI_COL_HDRPAD_STR
	/*   01234567[89ABCDEF] */
	"in_src_addr            "
	/*   123.123.123.123 */
	"max_frag      "
	/*   12345 */
	"ref     ");
	/*   123 */

	ire_walk_ill_mrtun(0, 0, ire_report_mrtun_table, (char *)mp, NULL);
	return (0);
}

/* mrtun report table - supports ipv4_mrtun_ire_status ndd variable */

static void
ire_report_mrtun_table(ire_t *ire, char *mp)
{
	char	buf1[INET_ADDRSTRLEN];
	int	ref;

	/* Number of active references of this ire */
	ref = ire->ire_refcnt;
	ASSERT(ire->ire_type == IRE_MIPRTUN);
	(void) mi_mpprintf((mblk_t *)mp,
	    MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR
	    "%s          %05d             %03d",
	    (void *)ire, (void *)ire->ire_stq,
	    (void *)ire->ire_in_ill,
	    ip_dot_addr(ire->ire_in_src_addr, buf1),
	    ire->ire_max_frag, ref);
}

/*
 * Dispatch routine to format ires in interface based routine
 */
/* ARGSUSED */
int
ip_ire_report_srcif(queue_t *q, mblk_t *mp, caddr_t arg, cred_t *ioc_cr)
{

	/* Report all interface based ires */

	(void) mi_mpprintf(mp,
	    "IRE      " MI_COL_HDRPAD_STR
	    /*   01234567[89ABCDEF] */
	    "stq      " MI_COL_HDRPAD_STR
	    /*   01234567[89ABCDEF] */
	    "in_ill    " MI_COL_HDRPAD_STR
	    /*   01234567[89ABCDEF] */
	    "addr            "
	    /*   123.123.123.123 */
	    "gateway         "
	    /*   123.123.123.123 */
	    "max_frag      "
	    /*   12345 */
	    "ref     "
	    /*   123 */
	    "type    "
	    /* ABCDEFGH */
	    "in/out/forward");
	ire_walk_srcif_table_v4(ire_report_srcif_table, (char *)mp);
	return (0);
}

/* Reports the interface table ires */
static void
ire_report_srcif_table(ire_t *ire, char *mp)
{
	char    buf1[INET_ADDRSTRLEN];
	char    buf2[INET_ADDRSTRLEN];
	int	ref;

	ref = ire->ire_refcnt;
	(void) mi_mpprintf((mblk_t *)mp,
	    MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR MI_COL_PTRFMT_STR
	    "%s    %s      %05d       %03d      %s     %d",
	    (void *)ire, (void *)ire->ire_stq,
	    (void *)ire->ire_in_ill,
	    ip_dot_addr(ire->ire_addr, buf1),
	    ip_dot_addr(ire->ire_gateway_addr, buf2),
	    ire->ire_max_frag, ref,
	    ip_nv_lookup(ire_nv_tbl, (int)ire->ire_type),
	    ire->ire_ib_pkt_count);

}
/*
 * ip_ire_req is called by ip_wput when an IRE_DB_REQ_TYPE message is handed
 * down from the Upper Level Protocol to request a copy of the IRE (to check
 * its type or to extract information like round-trip time estimates or the
 * MTU.)
 * The address is assumed to be in the ire_addr field. If no IRE is found
 * an IRE is returned with ire_type being zero.
 * Note that the upper lavel protocol has to check for broadcast
 * (IRE_BROADCAST) and multicast (CLASSD(addr)).
 * If there is a b_cont the resulting IRE_DB_TYPE mblk is placed at the
 * end of the returned message.
 *
 * TCP sends down a message of this type with a connection request packet
 * chained on. UDP and ICMP send it down to verify that a route exists for
 * the destination address when they get connected.
 */
void
ip_ire_req(queue_t *q, mblk_t *mp)
{
	ire_t	*inire;
	ire_t	*ire;
	mblk_t	*mp1;
	ire_t	*sire = NULL;
	zoneid_t zoneid = Q_TO_CONN(q)->conn_zoneid;

	if ((mp->b_wptr - mp->b_rptr) < sizeof (ire_t) ||
	    !OK_32PTR(mp->b_rptr)) {
		freemsg(mp);
		return;
	}
	inire = (ire_t *)mp->b_rptr;
	/*
	 * Got it, now take our best shot at an IRE.
	 */
	if (inire->ire_ipversion == IPV6_VERSION) {
		ire = ire_route_lookup_v6(&inire->ire_addr_v6, 0, 0, 0,
		    NULL, &sire, zoneid,
		    (MATCH_IRE_RECURSIVE | MATCH_IRE_DEFAULT));
	} else {
		ASSERT(inire->ire_ipversion == IPV4_VERSION);
		ire = ire_route_lookup(inire->ire_addr, 0, 0, 0,
		    NULL, &sire, zoneid,
		    (MATCH_IRE_RECURSIVE | MATCH_IRE_DEFAULT));
	}

	/*
	 * We prevent returning IRES with source address INADDR_ANY
	 * as these were temporarily created for sending packets
	 * from endpoints that have conn_unspec_src set.
	 */
	if (ire == NULL ||
	    (ire->ire_ipversion == IPV4_VERSION &&
	    ire->ire_src_addr == INADDR_ANY) ||
	    (ire->ire_ipversion == IPV6_VERSION &&
	    IN6_IS_ADDR_UNSPECIFIED(&ire->ire_src_addr_v6))) {
		inire->ire_type = 0;
	} else {
		bcopy(ire, inire, sizeof (ire_t));
		/* Copy the route metrics from the parent. */
		if (sire != NULL) {
			bcopy(&(sire->ire_uinfo), &(inire->ire_uinfo),
			    sizeof (iulp_t));
		}

		/*
		 * As we don't lookup global policy here, we may not
		 * pass the right size if per-socket policy is not
		 * present. For these cases, path mtu discovery will
		 * do the right thing.
		 */
		inire->ire_ipsec_overhead = conn_ipsec_length(Q_TO_CONN(q));

		/* Pass the latest setting of the ip_path_mtu_discovery */
		inire->ire_frag_flag |= (ip_path_mtu_discovery) ? IPH_DF : 0;
	}
	if (ire != NULL)
		ire_refrele(ire);
	if (sire != NULL)
		ire_refrele(sire);
	mp->b_wptr = &mp->b_rptr[sizeof (ire_t)];
	mp->b_datap->db_type = IRE_DB_TYPE;

	/* Put the IRE_DB_TYPE mblk last in the chain */
	mp1 = mp->b_cont;
	if (mp1 != NULL) {
		mp->b_cont = NULL;
		linkb(mp1, mp);
		mp = mp1;
	}
	qreply(q, mp);
}

/*
 * Send a packet using the specified IRE.
 * If ire_src_addr_v6 is all zero then discard the IRE after
 * the packet has been sent.
 */
static void
ire_send(queue_t *q, mblk_t *pkt, ire_t *ire)
{
	mblk_t *mp;
	mblk_t *ipsec_mp;
	boolean_t is_secure;
	uint_t ifindex;
	ill_t	*ill;

	ASSERT(ire->ire_ipversion == IPV4_VERSION);
	ipsec_mp = pkt;
	is_secure = (pkt->b_datap->db_type == M_CTL);
	if (is_secure)
		pkt = pkt->b_cont;

	/* If the packet originated externally then */
	if (pkt->b_prev) {
		ire_refrele(ire);
		/*
		 * Extract the ifindex from b_prev (set in ip_rput_noire).
		 * Look up interface to see if it still exists (it could have
		 * been unplumbed by the time the reply came back from ARP)
		 */
		ifindex = (uint_t)(uintptr_t)pkt->b_prev;
		ill = ill_lookup_on_ifindex(ifindex, B_FALSE,
		    NULL, NULL, NULL, NULL);
		if (ill == NULL) {
			pkt->b_prev = NULL;
			pkt->b_next = NULL;
			freemsg(ipsec_mp);
			return;
		}
		q = ill->ill_rq;
		pkt->b_prev = NULL;
		mp = allocb(0, BPRI_HI);
		if (mp == NULL) {
			ill_refrele(ill);
			pkt->b_next = NULL;
			freemsg(ipsec_mp);
			return;
		}
		mp->b_datap->db_type = M_BREAK;
		/*
		 * This packet has not gone through IPSEC processing
		 * and hence we should not have any IPSEC message
		 * prepended.
		 */
		ASSERT(ipsec_mp == pkt);
		mp->b_cont = ipsec_mp;
		put(q, mp);
		ill_refrele(ill);
	} else if (pkt->b_next) {
		/* Packets from multicast router */
		pkt->b_next = NULL;
		/*
		 * We never get the IPSEC_OUT while forwarding the
		 * packet for multicast router.
		 */
		ASSERT(ipsec_mp == pkt);
		ip_rput_forward(ire, (ipha_t *)pkt->b_rptr, ipsec_mp, NULL);
		ire_refrele(ire);
	} else {
		/* Locally originated packets */
		boolean_t is_inaddr_any;
		ipha_t *ipha = (ipha_t *)pkt->b_rptr;

		/*
		 * We need to do an ire_delete below for which
		 * we need to make sure that the IRE will be
		 * around even after calling ip_wput_ire -
		 * which does ire_refrele. Otherwise somebody
		 * could potentially delete this ire and hence
		 * free this ire and we will be calling ire_delete
		 * on a freed ire below.
		 */
		is_inaddr_any = (ire->ire_src_addr == INADDR_ANY);
		if (is_inaddr_any) {
			IRE_REFHOLD(ire);
		}
		/*
		 * If we were resolving a router we can not use the
		 * routers IRE for sending the packet (since it would
		 * violate the uniqness of the IP idents) thus we
		 * make another pass through ip_wput to create the IRE_CACHE
		 * for the destination.
		 * When IRE_MARK_NOADD is set, ire_add() is not called.
		 * Thus ip_wput() will never find a ire and result in an
		 * infinite loop. Thus we check whether IRE_MARK_NOADD is
		 * is set. This also implies that IRE_MARK_NOADD can only be
		 * used to send packets to directly connected hosts.
		 */
		if (ipha->ipha_dst != ire->ire_addr &&
		    !(ire->ire_marks & IRE_MARK_NOADD)) {
			ire_refrele(ire);	/* Held in ire_add */
			(void) ip_output(Q_TO_CONN(q), ipsec_mp, q, IRE_SEND);
		} else {
			if (is_secure) {
				ipsec_out_t *oi;
				ipha_t *ipha;

				oi = (ipsec_out_t *)ipsec_mp->b_rptr;
				ipha = (ipha_t *)ipsec_mp->b_cont->b_rptr;
				if (oi->ipsec_out_proc_begin) {
					/*
					 * This is the case where
					 * ip_wput_ipsec_out could not find
					 * the IRE and recreated a new one.
					 * As ip_wput_ipsec_out does ire
					 * lookups, ire_refrele for the extra
					 * bump in ire_add.
					 */
					ire_refrele(ire);
					ip_wput_ipsec_out(q, ipsec_mp, ipha,
					    NULL, NULL);
				} else {
					/*
					 * IRE_REFRELE will be done in
					 * ip_wput_ire.
					 */
					ip_wput_ire(q, ipsec_mp, ire, NULL,
					    IRE_SEND);
				}
			} else {
				/*
				 * IRE_REFRELE will be done in ip_wput_ire.
				 */
				ip_wput_ire(q, ipsec_mp, ire, NULL,
				    IRE_SEND);
			}
		}
		/*
		 * Special code to support sending a single packet with
		 * conn_unspec_src using an IRE which has no source address.
		 * The IRE is deleted here after sending the packet to avoid
		 * having other code trip on it. But before we delete the
		 * ire, somebody could have looked up this ire.
		 * We prevent returning/using this IRE by the upper layers
		 * by making checks to NULL source address in other places
		 * like e.g ip_ire_append, ip_ire_req and ip_bind_connected.
		 * Though, this does not completely prevent other threads
		 * from using this ire, this should not cause any problems.
		 *
		 * NOTE : We use is_inaddr_any instead of using ire_src_addr
		 * because for the normal case i.e !is_inaddr_any, ire_refrele
		 * above could have potentially freed the ire.
		 */
		if (is_inaddr_any) {
			/*
			 * If this IRE has been deleted by another thread, then
			 * ire_bucket won't be NULL, but ire_ptpn will be NULL.
			 * Thus, ire_delete will do nothing.  This check
			 * guards against calling ire_delete when the IRE was
			 * never inserted in the table, which is handled by
			 * ire_delete as dropping another reference.
			 */
			if (ire->ire_bucket != NULL) {
				ip1dbg(("ire_send: delete IRE\n"));
				ire_delete(ire);
			}
			ire_refrele(ire);	/* Held above */
		}
	}
}

/*
 * Send a packet using the specified IRE.
 * If ire_src_addr_v6 is all zero then discard the IRE after
 * the packet has been sent.
 */
static void
ire_send_v6(queue_t *q, mblk_t *pkt, ire_t *ire)
{
	mblk_t *ipsec_mp;
	boolean_t secure;
	uint_t ifindex;

	ASSERT(ire->ire_ipversion == IPV6_VERSION);
	if (pkt->b_datap->db_type == M_CTL) {
		ipsec_mp = pkt;
		pkt = pkt->b_cont;
		secure = B_TRUE;
	} else {
		ipsec_mp = pkt;
		secure = B_FALSE;
	}

	/* If the packet originated externally then */
	if (pkt->b_prev) {
		ill_t	*ill;
		/*
		 * Extract the ifindex from b_prev (set in ip_rput_data_v6).
		 * Look up interface to see if it still exists (it could have
		 * been unplumbed by the time the reply came back from the
		 * resolver). Unlike IPv4 there is no need for a prepended
		 * M_BREAK since ip_rput_data_v6 does not process options
		 * before finding an IRE.
		 */
		ifindex = (uint_t)(uintptr_t)pkt->b_prev;
		ill = ill_lookup_on_ifindex(ifindex, B_TRUE,
		    NULL, NULL, NULL, NULL);
		if (ill == NULL) {
			pkt->b_prev = NULL;
			pkt->b_next = NULL;
			freemsg(ipsec_mp);
			ire_refrele(ire);	/* Held in ire_add */
			return;
		}
		q = ill->ill_rq;
		pkt->b_prev = NULL;
		/*
		 * This packet has not gone through IPSEC processing
		 * and hence we should not have any IPSEC message
		 * prepended.
		 */
		ASSERT(ipsec_mp == pkt);
		put(q, pkt);
		ill_refrele(ill);
	} else if (pkt->b_next) {
		/* Packets from multicast router */
		pkt->b_next = NULL;
		/*
		 * We never get the IPSEC_OUT while forwarding the
		 * packet for multicast router.
		 */
		ASSERT(ipsec_mp == pkt);
		/*
		 * XXX TODO IPv6.
		 */
		freemsg(pkt);
#ifdef XXX
		ip_rput_forward(ire, (ipha_t *)pkt->b_rptr, pkt, NULL);
#endif
	} else {
		if (secure) {
			ipsec_out_t *oi;
			ip6_t *ip6h;

			oi = (ipsec_out_t *)ipsec_mp->b_rptr;
			ip6h = (ip6_t *)ipsec_mp->b_cont->b_rptr;
			if (oi->ipsec_out_proc_begin) {
				/*
				 * This is the case where
				 * ip_wput_ipsec_out could not find
				 * the IRE and recreated a new one.
				 */
				ip_wput_ipsec_out_v6(q, ipsec_mp, ip6h,
				    NULL, NULL);
			} else {
				(void) ip_output_v6(Q_TO_CONN(q), ipsec_mp,
				    q, IRE_SEND);
			}
		} else {
			/*
			 * Send packets through ip_output_v6 so that any
			 * ip6_info header can be processed again.
			 */
			(void) ip_output_v6(Q_TO_CONN(q), ipsec_mp, q,
			    IRE_SEND);
		}
		/*
		 * Special code to support sending a single packet with
		 * conn_unspec_src using an IRE which has no source address.
		 * The IRE is deleted here after sending the packet to avoid
		 * having other code trip on it. But before we delete the
		 * ire, somebody could have looked up this ire.
		 * We prevent returning/using this IRE by the upper layers
		 * by making checks to NULL source address in other places
		 * like e.g ip_ire_append_v6, ip_ire_req and
		 * ip_bind_connected_v6. Though, this does not completely
		 * prevent other threads from using this ire, this should
		 * not cause any problems.
		 */
		if (IN6_IS_ADDR_UNSPECIFIED(&ire->ire_src_addr_v6)) {
			ip1dbg(("ire_send_v6: delete IRE\n"));
			ire_delete(ire);
		}
	}
	ire_refrele(ire);	/* Held in ire_add */
}

/*
 * Make sure that IRE bucket does not get too long.
 * This can cause lock up because ire_cache_lookup()
 * may take "forever" to finish.
 *
 * We just remove cnt IREs each time.  This means that
 * the bucket length will stay approximately constant,
 * depending on cnt.  This should be enough to defend
 * against DoS attack based on creating temporary IREs
 * (for forwarding and non-TCP traffic).
 *
 * Note that new IRE is normally added at the tail of the
 * bucket.  This means that we are removing the "oldest"
 * temporary IRE added.  Only if there are IREs with
 * the same ire_addr, do we not add it at the tail.  Refer
 * to ire_add_v*().  It should be OK for our purpose.
 *
 * For non-temporary cached IREs, we make sure that they
 * have not been used for some time (defined below), they
 * are non-local destinations, and there is no one using
 * them at the moment (refcnt == 1).
 *
 * The above means that the IRE bucket length may become
 * very long, consisting of mostly non-temporary IREs.
 * This can happen when the hash function does a bad job
 * so that most TCP connections cluster to a specific bucket.
 * This "hopefully" should never happen.  It can also
 * happen if most TCP connections have very long lives.
 * Even with the minimal hash table size of 256, there
 * has to be a lot of such connections to make the bucket
 * length unreasonably long.  This should probably not
 * happen either.  The third can when this can happen is
 * when the machine is under attack, such as SYN flooding.
 * TCP should already have the proper mechanism to protect
 * that.  So we should be safe.
 *
 * This function is called by ire_add_then_send() after
 * a new IRE is added and the packet is sent.
 *
 * The idle cutoff interval is set to 60s.  It can be
 * changed using /etc/system.
 */
uint32_t ire_idle_cutoff_interval = 60000;

static void
ire_cache_cleanup(irb_t *irb, uint32_t threshold, int cnt)
{
	ire_t *ire;
	int tmp_cnt = cnt;
	clock_t cut_off = drv_usectohz(ire_idle_cutoff_interval * 1000);

	/*
	 * irb is NULL if the IRE is not added to the hash.  This
	 * happens when IRE_MARK_NOADD is set in ire_add_then_send()
	 * and when ires are returned from ire_update_srcif_v4() routine.
	 */
	if (irb == NULL)
		return;

	IRB_REFHOLD(irb);
	if (irb->irb_tmp_ire_cnt > threshold) {
		for (ire = irb->irb_ire; ire != NULL && tmp_cnt > 0;
		    ire = ire->ire_next) {
			if (ire->ire_marks & IRE_MARK_CONDEMNED)
				continue;
			if (ire->ire_marks & IRE_MARK_TEMPORARY) {
				ASSERT(ire->ire_type == IRE_CACHE);
				ire_delete(ire);
				tmp_cnt--;
			}
		}
	}
	if (irb->irb_ire_cnt - irb->irb_tmp_ire_cnt > threshold) {
		for (ire = irb->irb_ire; ire != NULL && cnt > 0;
		    ire = ire->ire_next) {
			if (ire->ire_marks & IRE_MARK_CONDEMNED ||
			    ire->ire_gateway_addr == 0) {
				continue;
			}
			if ((ire->ire_type == IRE_CACHE) &&
			    (lbolt - ire->ire_last_used_time > cut_off) &&
			    (ire->ire_refcnt == 1)) {
				ire_delete(ire);
				cnt--;
			}
		}
	}
	IRB_REFRELE(irb);
}

/*
 * ire_add_then_send is called when a new IRE has been created in order to
 * route an outgoing packet.  Typically, it is called from ip_wput when
 * a response comes back down from a resolver.  We add the IRE, and then
 * possibly run the packet through ip_wput or ip_rput, as appropriate.
 * However, we do not add the newly created IRE in the cache when
 * IRE_MARK_NOADD is set in the IRE. IRE_MARK_NOADD is set at
 * ip_newroute_ipif(). The ires with IRE_MARK_NOADD and ires returned
 * by ire_update_srcif_v4() are ire_refrele'd by ip_wput_ire() and get
 * deleted.
 * Multirouting support: the packet is silently discarded when the new IRE
 * holds the RTF_MULTIRT flag, but is not the first IRE to be added with the
 * RTF_MULTIRT flag for the same destination address.
 * In this case, we just want to register this additional ire without
 * sending the packet, as it has already been replicated through
 * existing multirt routes in ip_wput().
 */
void
ire_add_then_send(queue_t *q, ire_t *ire, mblk_t *mp)
{
	irb_t *irb;
	boolean_t drop = B_FALSE;
	/* LINTED : set but not used in function */
	boolean_t mctl_present;
	mblk_t *first_mp = NULL;
	mblk_t *save_mp = NULL;
	ire_t *dst_ire;
	ipha_t *ipha;
	ip6_t *ip6h;

	if (mp != NULL) {
		/*
		 * We first have to retrieve the destination address carried
		 * by the packet.
		 * We can't rely on ire as it can be related to a gateway.
		 * The destination address will help in determining if
		 * other RTF_MULTIRT ires are already registered.
		 *
		 * We first need to know where we are going : v4 or V6.
		 * the ire version is enough, as there is no risk that
		 * we resolve an IPv6 address with an IPv4 ire
		 * or vice versa.
		 */
		if (ire->ire_ipversion == IPV4_VERSION) {
			EXTRACT_PKT_MP(mp, first_mp, mctl_present);
			ipha = (ipha_t *)mp->b_rptr;
			save_mp = mp;
			mp = first_mp;

			dst_ire = ire_cache_lookup(ipha->ipha_dst,
			    ire->ire_zoneid);
		} else {
			/*
			 * Get a pointer to the beginning of the IPv6 header.
			 * Ignore leading IPsec control mblks.
			 */
			first_mp = mp;
			if (mp->b_datap->db_type == M_CTL) {
				mp = mp->b_cont;
			}
			ip6h = (ip6_t *)mp->b_rptr;
			save_mp = mp;
			mp = first_mp;
			dst_ire = ire_cache_lookup_v6(&ip6h->ip6_dst,
			    ire->ire_zoneid);
		}
		if (dst_ire != NULL) {
			if (dst_ire->ire_flags & RTF_MULTIRT) {
				/*
				 * At least one resolved multirt route
				 * already exists for the destination,
				 * don't sent this packet: either drop it
				 * or complete the pending resolution,
				 * depending on the ire.
				 */
				drop = B_TRUE;
			}
			ip1dbg(("ire_add_then_send: dst_ire %p "
			    "[dst %08x, gw %08x], drop %d\n",
			    (void *)dst_ire,
			    (dst_ire->ire_ipversion == IPV4_VERSION) ? \
				ntohl(dst_ire->ire_addr) : \
				ntohl(V4_PART_OF_V6(dst_ire->ire_addr_v6)),
			    (dst_ire->ire_ipversion == IPV4_VERSION) ? \
				ntohl(dst_ire->ire_gateway_addr) : \
				ntohl(V4_PART_OF_V6(
				    dst_ire->ire_gateway_addr_v6)),
			    drop));
			ire_refrele(dst_ire);
		}
	}

	if (!(ire->ire_marks & IRE_MARK_NOADD)) {
		/*
		 * Regular packets with cache bound ires and
		 * the packets from ARP response for ires which
		 * belong to the ire_srcif_v4 table, are here.
		 */
		if (ire->ire_in_ill == NULL) {
			/* Add the ire */
			(void) ire_add(&ire, NULL, NULL, NULL);
		} else {
			/*
			 * This must be ARP response for ire in interface based
			 * table. Note that we don't add them in cache table,
			 * instead we update the existing table with dlureq_mp
			 * information. The reverse tunnel ires do not come
			 * here, as reverse tunnel is non-resolver interface.
			 * XXX- another design alternative was to mark the
			 * ires in interface based table with a special mark to
			 * make absolutely sure that we operate in right ires.
			 * This idea was not implemented as part of code review
			 * suggestion, as ire_in_ill suffice to distinguish
			 * between the regular ires and interface based
			 * ires now and thus we save a bit in the ire_marks.
			 */
			ire = ire_update_srcif_v4(ire);
		}

		if (ire == NULL) {
			mp->b_prev = NULL;
			mp->b_next = NULL;
			MULTIRT_DEBUG_UNTAG(mp);
			freemsg(mp);
			return;
		}
		if (mp == NULL) {
			ire_refrele(ire);	/* Held in ire_add_v4/v6 */
			return;
		}
	}
	if (drop) {
		/*
		 * If we're adding an RTF_MULTIRT ire, the resolution
		 * is over: we just drop the packet.
		 */
		if (ire->ire_flags & RTF_MULTIRT) {
			if (save_mp) {
				save_mp->b_prev = NULL;
				save_mp->b_next = NULL;
			}
			MULTIRT_DEBUG_UNTAG(mp);
			freemsg(mp);
		} else {
			/*
			 * Otherwise, we're adding the ire to a gateway
			 * for a multirt route.
			 * Invoke ip_newroute() to complete the resolution
			 * of the route. We will then come back here and
			 * finally drop this packet in the above code.
			 */
			if (ire->ire_ipversion == IPV4_VERSION) {
				/*
				 * TODO: in order for CGTP to work in non-global
				 * zones, ip_newroute() must create the IRE
				 * cache in the zone indicated by
				 * ire->ire_zoneid.
				 */
				ip_newroute(q, mp, ipha->ipha_dst, 0,
				    (CONN_Q(q) ? Q_TO_CONN(q) : NULL));
			} else {
				ip_newroute_v6(q, mp, &ip6h->ip6_dst, NULL,
				    NULL, ire->ire_zoneid);
			}
		}

		ire_refrele(ire); /* As done by ire_send(). */
		return;
	}
	/*
	 * Need to remember ire_bucket here as ire_send*() may delete
	 * the ire so we cannot reference it after that.
	 */
	irb = ire->ire_bucket;
	if (ire->ire_ipversion == IPV6_VERSION) {
		ire_send_v6(q, mp, ire);
		/*
		 * Clean up more than 1 IRE so that the clean up does not
		 * need to be done every time when a new IRE is added and
		 * the threshold is reached.
		 */
		ire_cache_cleanup(irb, ip6_ire_max_bucket_cnt, 2);
	} else {
		ire_send(q, mp, ire);
		ire_cache_cleanup(irb, ip_ire_max_bucket_cnt, 2);
	}
}

/*
 * Initialize the ire that is specific to IPv4 part and call
 * ire_init_common to finish it.
 */
ire_t *
ire_init(ire_t *ire, uchar_t *addr, uchar_t *mask, uchar_t *src_addr,
    uchar_t *gateway, uchar_t *in_src_addr, uint_t *max_fragp, mblk_t *fp_mp,
    queue_t *rfq, queue_t *stq, ushort_t type, mblk_t *dlureq_mp, ipif_t *ipif,
    ill_t *in_ill, ipaddr_t cmask, uint32_t phandle, uint32_t ihandle,
    uint32_t flags, const iulp_t *ulp_info)
{
	if (fp_mp != NULL) {
		/*
		 * We can't dupb() here as multiple threads could be
		 * calling dupb on the same mp which is incorrect.
		 * First dupb() should be called only by one thread.
		 */
		fp_mp = copyb(fp_mp);
		if (fp_mp == NULL)
			return (NULL);
	}

	if (dlureq_mp != NULL) {
		/*
		 * We can't dupb() here as multiple threads could be
		 * calling dupb on the same mp which is incorrect.
		 * First dupb() should be called only by one thread.
		 */
		dlureq_mp = copyb(dlureq_mp);
		if (dlureq_mp == NULL) {
			if (fp_mp != NULL)
				freeb(fp_mp);
			return (NULL);
		}
	}

	/*
	 * Check that IRE_IF_RESOLVER and IRE_IF_NORESOLVER have a
	 * dlureq_mp which is the ill_resolver_mp for IRE_IF_RESOLVER
	 * and DL_UNITDATA_REQ for IRE_IF_NORESOLVER.
	 */
	if ((type & IRE_INTERFACE) &&
	    dlureq_mp == NULL) {
		ASSERT(fp_mp == NULL);
		ip0dbg(("ire_init: no dlureq_mp\n"));
		return (NULL);
	}

	BUMP_IRE_STATS(ire_stats_v4, ire_stats_alloced);

	if (addr != NULL)
		bcopy(addr, &ire->ire_addr, IP_ADDR_LEN);
	if (src_addr != NULL)
		bcopy(src_addr, &ire->ire_src_addr, IP_ADDR_LEN);
	if (mask != NULL) {
		bcopy(mask, &ire->ire_mask, IP_ADDR_LEN);
		ire->ire_masklen = ip_mask_to_plen(ire->ire_mask);
	}
	if (gateway != NULL) {
		bcopy(gateway, &ire->ire_gateway_addr, IP_ADDR_LEN);
	}
	if (in_src_addr != NULL) {
		bcopy(in_src_addr, &ire->ire_in_src_addr, IP_ADDR_LEN);
	}

	if (type == IRE_CACHE)
		ire->ire_cmask = cmask;

	ire_init_common(ire, max_fragp, fp_mp, rfq, stq, type, dlureq_mp,
	    ipif, in_ill, phandle, ihandle, flags, IPV4_VERSION, ulp_info);

	return (ire);
}

/*
 * Similar to ire_create except that it is called only when
 * we want to allocate ire as an mblk e.g. we have an external
 * resolver ARP.
 */
ire_t *
ire_create_mp(uchar_t *addr, uchar_t *mask, uchar_t *src_addr, uchar_t *gateway,
    uchar_t *in_src_addr, uint_t max_frag, mblk_t *fp_mp, queue_t *rfq,
    queue_t *stq, ushort_t type, mblk_t *dlureq_mp, ipif_t *ipif, ill_t *in_ill,
    ipaddr_t cmask, uint32_t phandle, uint32_t ihandle, uint32_t flags,
    const iulp_t *ulp_info)
{
	ire_t	*ire;
	ire_t	*ret_ire;
	mblk_t	*mp;

	/* Allocate the new IRE. */
	mp = allocb(sizeof (ire_t), BPRI_MED);
	if (mp == NULL) {
		ip1dbg(("ire_create_mp: alloc failed\n"));
		return (NULL);
	}

	ire = (ire_t *)mp->b_rptr;
	mp->b_wptr = (uchar_t *)&ire[1];

	/* Start clean. */
	*ire = ire_null;
	ire->ire_mp = mp;
	mp->b_datap->db_type = IRE_DB_TYPE;

	ret_ire = ire_init(ire, addr, mask, src_addr, gateway, in_src_addr,
	    NULL, fp_mp, rfq, stq, type, dlureq_mp, ipif, in_ill, cmask,
	    phandle, ihandle, flags, ulp_info);

	if (ret_ire == NULL) {
		freeb(ire->ire_mp);
		return (NULL);
	}
	ASSERT(ret_ire == ire);
	/*
	 * ire_max_frag is normally zero here and is atomically set
	 * under the irebucket lock in ire_add_v[46] except for the
	 * case of IRE_MARK_NOADD. In that event the the ire_max_frag
	 * is non-zero here.
	 */
	ire->ire_max_frag = max_frag;
	return (ire);
}

/*
 * 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 *src_addr, uchar_t *gateway,
    uchar_t *in_src_addr, uint_t *max_fragp, mblk_t *fp_mp, queue_t *rfq,
    queue_t *stq, ushort_t type, mblk_t *dlureq_mp, ipif_t *ipif, ill_t *in_ill,
    ipaddr_t cmask, uint32_t phandle, uint32_t ihandle, uint32_t flags,
    const iulp_t *ulp_info)
{
	ire_t	*ire;
	ire_t	*ret_ire;

	ire = kmem_cache_alloc(ire_cache, KM_NOSLEEP);
	if (ire == NULL) {
		ip1dbg(("ire_create: alloc failed\n"));
		return (NULL);
	}
	*ire = ire_null;

	ret_ire = ire_init(ire, addr, mask, src_addr, gateway, in_src_addr,
	    max_fragp, fp_mp, rfq, stq, type, dlureq_mp, ipif, in_ill,  cmask,
	    phandle, ihandle, flags, ulp_info);

	if (ret_ire == NULL) {
		kmem_cache_free(ire_cache, ire);
		return (NULL);
	}
	ASSERT(ret_ire == ire);
	return (ire);
}


/*
 * Common to IPv4 and IPv6
 */
void
ire_init_common(ire_t *ire, uint_t *max_fragp, mblk_t *fp_mp,
    queue_t *rfq, queue_t *stq, ushort_t type,
    mblk_t *dlureq_mp, ipif_t *ipif, ill_t *in_ill, uint32_t phandle,
    uint32_t ihandle, uint32_t flags, uchar_t ipversion,
    const iulp_t *ulp_info)
{
	ire->ire_max_fragp = max_fragp;
	ire->ire_frag_flag |= (ip_path_mtu_discovery) ? IPH_DF : 0;

	ASSERT(fp_mp == NULL || fp_mp->b_datap->db_type == M_DATA);
	if (ipif) {
		if (ipif->ipif_isv6)
			ASSERT(ipversion == IPV6_VERSION);
		else
			ASSERT(ipversion == IPV4_VERSION);
	}

	ire->ire_fp_mp = fp_mp;
	ire->ire_dlureq_mp = dlureq_mp;
	ire->ire_stq = stq;
	ire->ire_rfq = rfq;
	ire->ire_type = type;
	ire->ire_flags = RTF_UP | flags;
	ire->ire_ident = TICK_TO_MSEC(lbolt);
	bcopy(ulp_info, &ire->ire_uinfo, sizeof (iulp_t));

	ire->ire_tire_mark = ire->ire_ob_pkt_count + ire->ire_ib_pkt_count;
	ire->ire_last_used_time = lbolt;
	ire->ire_create_time = (uint32_t)gethrestime_sec();

	/*
	 * If this IRE is an IRE_CACHE, inherit the handles from the
	 * parent IREs. For others in the forwarding table, assign appropriate
	 * new ones.
	 *
	 * The mutex protecting ire_handle is because ire_create is not always
	 * called as a writer.
	 */
	if (ire->ire_type & IRE_OFFSUBNET) {
		mutex_enter(&ire_handle_lock);
		ire->ire_phandle = (uint32_t)ire_handle++;
		mutex_exit(&ire_handle_lock);
	} else if (ire->ire_type & IRE_INTERFACE) {
		mutex_enter(&ire_handle_lock);
		ire->ire_ihandle = (uint32_t)ire_handle++;
		mutex_exit(&ire_handle_lock);
	} else if (ire->ire_type == IRE_CACHE) {
		ire->ire_phandle = phandle;
		ire->ire_ihandle = ihandle;
	}
	ire->ire_in_ill = in_ill;
	ire->ire_ipif = ipif;
	if (ipif != NULL) {
		ire->ire_ipif_seqid = ipif->ipif_seqid;
		ire->ire_zoneid = ipif->ipif_zoneid;
	} else {
		ire->ire_zoneid = GLOBAL_ZONEID;
	}
	ire->ire_ipversion = ipversion;
	ire->ire_refcnt = 1;
	mutex_init(&ire->ire_lock, NULL, MUTEX_DEFAULT, NULL);

#ifdef IRE_DEBUG
	bzero(ire->ire_trace, sizeof (th_trace_t *) * IP_TR_HASH_MAX);
#endif
}

/*
 * This routine is called repeatedly by ipif_up to create broadcast IREs.
 * It is passed a pointer to a slot in an IRE pointer array into which to
 * place the pointer to the new IRE, if indeed we create one.  If the
 * IRE corresponding to the address passed in would be a duplicate of an
 * existing one, we don't create the new one.  irep is incremented before
 * return only if we do create a new IRE.  (Always called as writer.)
 *
 * Note that with the "match_flags" parameter, we can match on either
 * a particular logical interface (MATCH_IRE_IPIF) or for all logical
 * interfaces for a given physical interface (MATCH_IRE_ILL).  Currently,
 * we only create broadcast ire's on a per physical interface basis. If
 * someone is going to be mucking with logical interfaces, it is important
 * to call "ipif_check_bcast_ires()" to make sure that any change to a
 * logical interface will not cause critical broadcast IRE's to be deleted.
 */
ire_t **
ire_check_and_create_bcast(ipif_t *ipif, ipaddr_t  addr, ire_t **irep,
    int match_flags)
{
	ire_t *ire;
	uint64_t check_flags = IPIF_DEPRECATED | IPIF_NOLOCAL | IPIF_ANYCAST;

	/*
	 * No broadcast IREs for the LOOPBACK interface
	 * or others such as point to point and IPIF_NOXMIT.
	 */
	if (!(ipif->ipif_flags & IPIF_BROADCAST) ||
	    (ipif->ipif_flags & IPIF_NOXMIT))
		return (irep);

	/* If this would be a duplicate, don't bother. */
	if ((ire = ire_ctable_lookup(addr, 0, IRE_BROADCAST, ipif,
	    ipif->ipif_zoneid, match_flags)) != NULL) {
		/*
		 * We look for non-deprecated (and non-anycast, non-nolocal)
		 * ipifs as the best choice. ipifs with check_flags matching
		 * (deprecated, etc) are used only if non-deprecated ipifs
		 * are not available. if the existing ire's ipif is deprecated
		 * and the new ipif is non-deprecated, switch to the new ipif
		 */
		if ((!(ire->ire_ipif->ipif_flags & check_flags)) ||
		    (ipif->ipif_flags & check_flags)) {
			ire_refrele(ire);
			return (irep);
		}
		/*
		 * Bcast ires exist in pairs. Both have to be deleted,
		 * Since we are exclusive we can make the above assertion.
		 * The 1st has to be refrele'd since it was ctable_lookup'd.
		 */
		ASSERT(IAM_WRITER_IPIF(ipif));
		ASSERT(ire->ire_next->ire_addr == ire->ire_addr);
		ire_delete(ire->ire_next);
		ire_delete(ire);
		ire_refrele(ire);
	}

	irep = ire_create_bcast(ipif, addr, irep);

	return (irep);
}

uint_t ip_loopback_mtu = IP_LOOPBACK_MTU;

/*
 * This routine is called from ipif_check_bcast_ires and ire_check_bcast.
 * It leaves all the verifying and deleting to those routines. So it always
 * creates 2 bcast ires and chains them into the ire array passed in.
 */
ire_t **
ire_create_bcast(ipif_t *ipif, ipaddr_t  addr, ire_t **irep)
{
	*irep++ = ire_create(
	    (uchar_t *)&addr,			/* dest addr */
	    (uchar_t *)&ip_g_all_ones,		/* mask */
	    (uchar_t *)&ipif->ipif_src_addr,	/* source addr */
	    NULL,				/* no gateway */
	    NULL,				/* no in_src_addr */
	    &ipif->ipif_mtu,			/* max frag */
	    NULL,				/* fast path header */
	    ipif->ipif_rq,			/* recv-from queue */
	    ipif->ipif_wq,			/* send-to queue */
	    IRE_BROADCAST,
	    ipif->ipif_bcast_mp,		/* xmit header */
	    ipif,
	    NULL,
	    0,
	    0,
	    0,
	    0,
	    &ire_uinfo_null);

	*irep++ = ire_create(
		(uchar_t *)&addr,		 /* dest address */
		(uchar_t *)&ip_g_all_ones,	 /* mask */
		(uchar_t *)&ipif->ipif_src_addr, /* source address */
		NULL,				 /* no gateway */
		NULL,				 /* no in_src_addr */
		&ip_loopback_mtu,		 /* max frag size */
		NULL,				 /* Fast Path header */
		ipif->ipif_rq,			 /* recv-from queue */
		NULL,				 /* no send-to queue */
		IRE_BROADCAST,		/* Needed for fanout in wput */
		NULL,
		ipif,
		NULL,
		0,
		0,
		0,
		0,
		&ire_uinfo_null);

	return (irep);
}

/*
 * ire_walk routine to delete or update any IRE_CACHE that might contain
 * stale information.
 * The flags state which entries to delete or update.
 * Garbage collection is done separately using kmem alloc callbacks to
 * ip_trash_ire_reclaim.
 * Used for both IPv4 and IPv6. However, IPv6 only uses FLUSH_MTU_TIME
 * since other stale information is cleaned up using NUD.
 */
void
ire_expire(ire_t *ire, char *arg)
{
	int flush_flags = (int)(uintptr_t)arg;
	ill_t	*stq_ill;

	if ((flush_flags & FLUSH_REDIRECT_TIME) &&
	    ire->ire_type == IRE_HOST_REDIRECT) {
		/* Make sure we delete the corresponding IRE_CACHE */
		ip1dbg(("ire_expire: all redirects\n"));
		ip_rts_rtmsg(RTM_DELETE, ire, 0);
		ire_delete(ire);
		return;
	}
	if (ire->ire_type != IRE_CACHE)
		return;

	if (flush_flags & FLUSH_ARP_TIME) {
		/*
		 * Remove all IRE_CACHE.
		 * Verify that create time is more than
		 * ip_ire_arp_interval milliseconds ago.
		 */
		if (((uint32_t)gethrestime_sec() - ire->ire_create_time) *
		    MILLISEC > ip_ire_arp_interval) {
			ip1dbg(("ire_expire: all IRE_CACHE\n"));
			ire_delete(ire);
			return;
		}
	}

	if (ip_path_mtu_discovery && (flush_flags & FLUSH_MTU_TIME) &&
	    (ire->ire_ipif != NULL)) {
		/* Increase pmtu if it is less than the interface mtu */
		mutex_enter(&ire->ire_lock);
		/*
		 * If the ipif is a vni (whose mtu is 0, since it's virtual)
		 * get the mtu from the sending interfaces' ipif
		 */
		if (IS_VNI(ire->ire_ipif->ipif_ill)) {
			stq_ill = ire->ire_stq->q_ptr;
			ire->ire_max_frag = MIN(stq_ill->ill_ipif->ipif_mtu,
			    IP_MAXPACKET);
		} else {
			ire->ire_max_frag = MIN(ire->ire_ipif->ipif_mtu,
			    IP_MAXPACKET);
		}
		ire->ire_frag_flag |= IPH_DF;
		mutex_exit(&ire->ire_lock);
	}
}

/*
 * Do fast path probing if necessary.
 */
static void
ire_fastpath(ire_t *ire)
{
	ill_t	*ill;
	int res;

	if (ire->ire_fp_mp != NULL || ire->ire_dlureq_mp == NULL ||
	    (ire->ire_stq == NULL)) {
		/*
		 * Already contains fastpath info or
		 * doesn't have DL_UNITDATA_REQ header
		 * or is a loopback broadcast ire i.e. no stq.
		 */
		return;
	}
	ill = ire_to_ill(ire);
	if (ill == NULL)
		return;
	ire_fastpath_list_add(ill, ire);
	res = ill_fastpath_probe(ill, ire->ire_dlureq_mp);
	/*
	 * EAGAIN is an indication of a transient error
	 * i.e. allocation failure etc. leave the ire in the list it will
	 * be updated when another probe happens for another ire if not
	 * it will be taken out of the list when the ire is deleted.
	 */
	if (res != 0 && res != EAGAIN)
		ire_fastpath_list_delete(ill, ire);
}

/*
 * Update all IRE's that are not in fastpath mode and
 * have an dlureq_mp that matches mp. mp->b_cont contains
 * the fastpath header.
 *
 * Returns TRUE if entry should be dequeued, or FALSE otherwise.
 */
boolean_t
ire_fastpath_update(ire_t *ire, void *arg)
{
	mblk_t 	*mp, *fp_mp;
	uchar_t 	*up, *up2;
	ptrdiff_t	cmplen;

	ASSERT((ire->ire_type & (IRE_CACHE | IRE_BROADCAST |
	    IRE_MIPRTUN)) != 0);

	/*
	 * Already contains fastpath info or doesn't have
	 * DL_UNITDATA_REQ header.
	 */
	if (ire->ire_fp_mp != NULL || ire->ire_dlureq_mp == NULL)
		return (B_TRUE);

	ip2dbg(("ire_fastpath_update: trying\n"));
	mp = arg;
	up = mp->b_rptr;
	cmplen = mp->b_wptr - up;
	/* Serialize multiple fast path updates */
	mutex_enter(&ire->ire_lock);
	up2 = ire->ire_dlureq_mp->b_rptr;
	ASSERT(cmplen >= 0);
	if (ire->ire_dlureq_mp->b_wptr - up2 != cmplen ||
	    bcmp(up, up2, cmplen) != 0) {
		mutex_exit(&ire->ire_lock);
		/*
		 * Don't take the ire off the fastpath list yet,
		 * since the response may come later.
		 */
		return (B_FALSE);
	}
	/* Matched - install mp as the ire_fp_mp */
	ip1dbg(("ire_fastpath_update: match\n"));
	fp_mp = dupb(mp->b_cont);
	if (fp_mp) {
		/*
		 * We checked ire_fp_mp above. Check it again with the
		 * lock. Update fp_mp only if it has not been done
		 * already.
		 */
		if (ire->ire_fp_mp == NULL) {
			/*
			 * ire_ll_hdr_length is just an optimization to
			 * store the length. It is used to return the
			 * fast path header length to the upper layers.
			 */
			ire->ire_fp_mp = fp_mp;
			ire->ire_ll_hdr_length =
			    (uint_t)(fp_mp->b_wptr - fp_mp->b_rptr);
		} else {
			freeb(fp_mp);
		}
	}
	mutex_exit(&ire->ire_lock);
	return (B_TRUE);
}

/*
 * This function handles the DL_NOTE_FASTPATH_FLUSH notification from the
 * driver.
 */
/* ARGSUSED */
void
ire_fastpath_flush(ire_t *ire, void *arg)
{
	ill_t	*ill;
	int	res;

	/* No fastpath info? */
	if (ire->ire_fp_mp == NULL || ire->ire_dlureq_mp == NULL)
		return;

	/*
	 * Just remove the IRE if it is for non-broadcast dest.  Then
	 * we will create another one which will have the correct
	 * fastpath info.
	 */
	switch (ire->ire_type) {
	case IRE_CACHE:
		ire_delete(ire);
		break;
	case IRE_MIPRTUN:
	case IRE_BROADCAST:
		/*
		 * We can't delete the ire since it is difficult to
		 * recreate these ire's without going through the
		 * ipif down/up dance. The ire_fp_mp is protected by the
		 * ire_lock in the case of IRE_MIPRTUN and IRE_BROADCAST.
		 * All access to ire_fp_mp in the case of these 2 ire types
		 * is protected by ire_lock.
		 */
		mutex_enter(&ire->ire_lock);
		if (ire->ire_fp_mp != NULL) {
			freeb(ire->ire_fp_mp);
			ire->ire_fp_mp = NULL;
			mutex_exit(&ire->ire_lock);
			/*
			 * No fastpath probe if there is no stq i.e.
			 * i.e. the case of loopback broadcast ire.
			 */
			if (ire->ire_stq == NULL)
				break;
			ill = (ill_t *)((ire->ire_stq)->q_ptr);
			ire_fastpath_list_add(ill, ire);
			res = ill_fastpath_probe(ill, ire->ire_dlureq_mp);
			/*
			 * EAGAIN is an indication of a transient error
			 * i.e. allocation failure etc. leave the ire in the
			 * list it will be updated when another probe happens
			 * for another ire if not it will be taken out of the
			 * list when the ire is deleted.
			 */
			if (res != 0 && res != EAGAIN)
				ire_fastpath_list_delete(ill, ire);
		} else {
			mutex_exit(&ire->ire_lock);
		}
		break;
	default:
		/* This should not happen! */
		ip0dbg(("ire_fastpath_flush: Wrong ire type %s\n",
		    ip_nv_lookup(ire_nv_tbl, (int)ire->ire_type)));
		break;
	}
}

/*
 * Drain the list of ire's waiting for fastpath response.
 */
void
ire_fastpath_list_dispatch(ill_t *ill, boolean_t (*func)(ire_t *, void *),
    void *arg)
{
	ire_t	 *next_ire;
	ire_t	 *current_ire;
	ire_t	 *first_ire;
	ire_t	 *prev_ire = NULL;

	ASSERT(ill != NULL);

	mutex_enter(&ill->ill_lock);
	first_ire = current_ire = (ire_t *)ill->ill_fastpath_list;
	while (current_ire != (ire_t *)&ill->ill_fastpath_list) {
		next_ire = current_ire->ire_fastpath;
		/*
		 * Take it off the list if we're flushing, or if the callback
		 * routine tells us to do so.  Otherwise, leave the ire in the
		 * fastpath list to handle any pending response from the lower
		 * layer.  We can't drain the list when the callback routine
		 * comparison failed, because the response is asynchronous in
		 * nature, and may not arrive in the same order as the list
		 * insertion.
		 */
		if (func == NULL || func(current_ire, arg)) {
			current_ire->ire_fastpath = NULL;
			if (current_ire == first_ire)
				ill->ill_fastpath_list = first_ire = next_ire;
			else
				prev_ire->ire_fastpath = next_ire;
		} else {
			/* previous element that is still in the list */
			prev_ire = current_ire;
		}
		current_ire = next_ire;
	}
	mutex_exit(&ill->ill_lock);
}

/*
 * Add ire to the ire fastpath list.
 */
static void
ire_fastpath_list_add(ill_t *ill, ire_t *ire)
{
	ASSERT(ill != NULL);
	ASSERT(ire->ire_stq != NULL);

	rw_enter(&ire->ire_bucket->irb_lock, RW_READER);
	mutex_enter(&ill->ill_lock);

	/*
	 * if ire has not been deleted and
	 * is not already in the list add it.
	 */
	if (((ire->ire_marks & IRE_MARK_CONDEMNED) == 0) &&
	    (ire->ire_fastpath == NULL)) {
		ire->ire_fastpath = (ire_t *)ill->ill_fastpath_list;
		ill->ill_fastpath_list = ire;
	}

	mutex_exit(&ill->ill_lock);
	rw_exit(&ire->ire_bucket->irb_lock);
}

/*
 * remove ire from the ire fastpath list.
 */
void
ire_fastpath_list_delete(ill_t *ill, ire_t *ire)
{
	ire_t	*ire_ptr;

	ASSERT(ire->ire_stq != NULL && ill != NULL);

	mutex_enter(&ill->ill_lock);
	if (ire->ire_fastpath == NULL)
		goto done;

	ASSERT(ill->ill_fastpath_list != &ill->ill_fastpath_list);

	if (ill->ill_fastpath_list == ire) {
		ill->ill_fastpath_list = ire->ire_fastpath;
	} else {
		ire_ptr = ill->ill_fastpath_list;
		while (ire_ptr != (ire_t *)&ill->ill_fastpath_list) {
			if (ire_ptr->ire_fastpath == ire) {
				ire_ptr->ire_fastpath = ire->ire_fastpath;
				break;
			}
			ire_ptr = ire_ptr->ire_fastpath;
		}
	}
	ire->ire_fastpath = NULL;
done:
	mutex_exit(&ill->ill_lock);
}


/*
 * Find an IRE_INTERFACE for the multicast group.
 * Allows different routes for multicast addresses
 * in the unicast routing table (akin to 224.0.0.0 but could be more specific)
 * which point at different interfaces. This is used when IP_MULTICAST_IF
 * isn't specified (when sending) and when IP_ADD_MEMBERSHIP doesn't
 * specify the interface to join on.
 *
 * Supports IP_BOUND_IF by following the ipif/ill when recursing.
 */
ire_t *
ire_lookup_multi(ipaddr_t group, zoneid_t zoneid)
{
	ire_t	*ire;
	ipif_t	*ipif = NULL;
	int	match_flags = MATCH_IRE_TYPE;
	ipaddr_t gw_addr;

	ire = ire_ftable_lookup(group, 0, 0, 0, NULL, NULL, zoneid,
	    0, MATCH_IRE_DEFAULT);

	/* We search a resolvable ire in case of multirouting. */
	if ((ire != NULL) && (ire->ire_flags & RTF_MULTIRT)) {
		ire_t *cire = NULL;
		/*
		 * If the route is not resolvable, the looked up ire
		 * may be changed here. In that case, ire_multirt_lookup()
		 * IRE_REFRELE the original ire and change it.
		 */
		(void) ire_multirt_lookup(&cire, &ire, MULTIRT_CACHEGW);
		if (cire != NULL)
			ire_refrele(cire);
	}
	if (ire == NULL)
		return (NULL);
	/*
	 * Make sure we follow ire_ipif.
	 *
	 * We need to determine the interface route through
	 * which the gateway will be reached. We don't really
	 * care which interface is picked if the interface is
	 * part of a group.
	 */
	if (ire->ire_ipif != NULL) {
		ipif = ire->ire_ipif;
		match_flags |= MATCH_IRE_ILL_GROUP;
	}

	switch (ire->ire_type) {
	case IRE_DEFAULT:
	case IRE_PREFIX:
	case IRE_HOST:
		gw_addr = ire->ire_gateway_addr;
		ire_refrele(ire);
		ire = ire_ftable_lookup(gw_addr, 0, 0,
		    IRE_INTERFACE, ipif, NULL, zoneid, 0,
		    match_flags);
		return (ire);
	case IRE_IF_NORESOLVER:
	case IRE_IF_RESOLVER:
		return (ire);
	default:
		ire_refrele(ire);
		return (NULL);
	}
}

/*
 * Return any local address.  We use this to target ourselves
 * when the src address was specified as 'default'.
 * Preference for IRE_LOCAL entries.
 */
ire_t *
ire_lookup_local(zoneid_t zoneid)
{
	ire_t	*ire;
	irb_t	*irb;
	ire_t	*maybe = NULL;
	int i;

	for (i = 0; i < ip_cache_table_size;  i++) {
		irb = &ip_cache_table[i];
		if (irb->irb_ire == NULL)
			continue;
		rw_enter(&irb->irb_lock, RW_READER);
		for (ire = irb->irb_ire; ire != NULL; ire = ire->ire_next) {
			if ((ire->ire_marks & IRE_MARK_CONDEMNED) ||
			    ire->ire_zoneid != zoneid)
				continue;
			switch (ire->ire_type) {
			case IRE_LOOPBACK:
				if (maybe == NULL) {
					IRE_REFHOLD(ire);
					maybe = ire;
				}
				break;
			case IRE_LOCAL:
				if (maybe != NULL) {
					ire_refrele(maybe);
				}
				IRE_REFHOLD(ire);
				rw_exit(&irb->irb_lock);
				return (ire);
			}
		}
		rw_exit(&irb->irb_lock);
	}
	return (maybe);
}

/*
 * If the specified IRE is associated with a particular ILL, return
 * that ILL pointer (May be called as writer.).
 *
 * NOTE : This is not a generic function that can be used always.
 * This function always returns the ill of the outgoing packets
 * if this ire is used.
 */
ill_t *
ire_to_ill(ire_t *ire)
{
	ill_t *ill = NULL;

	/*
	 * 1) For an IRE_CACHE, ire_ipif is the one where it obtained
	 *    the source address from. ire_stq is the one where the
	 *    packets will be sent out on. We return that here.
	 *
	 * 2) IRE_BROADCAST normally has a loopback and a non-loopback
	 *    copy and they always exist next to each other with loopback
	 *    copy being the first one. If we are called on the non-loopback
	 *    copy, return the one pointed by ire_stq. If it was called on
	 *    a loopback copy, we still return the one pointed by the next
	 *    ire's ire_stq pointer i.e the one pointed by the non-loopback
	 *    copy. We don't want use ire_ipif as it might represent the
	 *    source address (if we borrow source addresses for
	 *    IRE_BROADCASTS in the future).
	 *    However if an interface is currently coming up, the above
	 *    condition may not hold during that period since the ires
	 *    are added one at a time. Thus one of the pair could have been
	 *    added and the other not yet added.
	 * 3) For all others return the ones pointed by ire_ipif->ipif_ill.
	 */

	if (ire->ire_type == IRE_CACHE) {
		ill = (ill_t *)ire->ire_stq->q_ptr;
	} else if (ire->ire_type == IRE_BROADCAST) {
		if (ire->ire_stq != NULL) {
			ill = (ill_t *)ire->ire_stq->q_ptr;
		} else {
			ire_t  *ire_next;

			ire_next = ire->ire_next;
			if (ire_next != NULL &&
			    ire_next->ire_type == IRE_BROADCAST &&
			    ire_next->ire_addr == ire->ire_addr &&
			    ire_next->ire_ipif == ire->ire_ipif) {
				ill = (ill_t *)ire_next->ire_stq->q_ptr;
			}
		}
	} else if (ire->ire_ipif != NULL) {
		ill = ire->ire_ipif->ipif_ill;
	}
	return (ill);
}

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

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

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

/*
 * Walk a particular version. version == 0 means both v4 and v6.
 */
static void
ire_walk_ipvers(pfv_t func, char *arg, uchar_t vers, zoneid_t zoneid)
{
	if (vers != IPV6_VERSION) {
		ire_walk_ill_tables(0, 0, func, arg, IP_MASK_TABLE_SIZE,
		    ip_ftable_hash_size, ip_forwarding_table,
		    ip_cache_table_size, ip_cache_table, NULL, zoneid);
	}
	if (vers != IPV4_VERSION) {
		ire_walk_ill_tables(0, 0, func, arg, IP6_MASK_TABLE_SIZE,
		    ip6_ftable_hash_size, ip_forwarding_table_v6,
		    ip6_cache_table_size, ip_cache_table_v6, NULL, zoneid);
	}
}

/*
 * 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, char *arg,
    ill_t *ill)
{
	ire_walk_ill_ipvers(match_flags, ire_type, func, arg, 0, ill);
}

void
ire_walk_ill_v4(uint_t match_flags, uint_t ire_type, pfv_t func, char *arg,
    ill_t *ill)
{
	ire_walk_ill_ipvers(match_flags, ire_type, func, arg, IPV4_VERSION,
	    ill);
}

void
ire_walk_ill_v6(uint_t match_flags, uint_t ire_type, pfv_t func, char *arg,
    ill_t *ill)
{
	ire_walk_ill_ipvers(match_flags, ire_type, func, arg, IPV6_VERSION,
	    ill);
}

/*
 * Walk a particular ill and version. version == 0 means both v4 and v6.
 */
static void
ire_walk_ill_ipvers(uint_t match_flags, uint_t ire_type, pfv_t func,
    char *arg, uchar_t vers, ill_t *ill)
{
	if (vers != IPV6_VERSION) {
		ire_walk_ill_tables(match_flags, ire_type, func, arg,
		    IP_MASK_TABLE_SIZE, ip_ftable_hash_size,
		    ip_forwarding_table, ip_cache_table_size,
		    ip_cache_table, ill, ALL_ZONES);
	}
	if (vers != IPV4_VERSION) {
		ire_walk_ill_tables(match_flags, ire_type, func, arg,
		    IP6_MASK_TABLE_SIZE, ip6_ftable_hash_size,
		    ip_forwarding_table_v6, ip6_cache_table_size,
		    ip_cache_table_v6, ill, ALL_ZONES);
	}
}

static boolean_t
ire_walk_ill_match(uint_t match_flags, uint_t ire_type, ire_t *ire,
    ill_t *ill, zoneid_t zoneid)
{
	ill_t *ire_stq_ill = NULL;
	ill_t *ire_ipif_ill = NULL;
	ill_group_t *ire_ill_group = NULL;

	ASSERT(match_flags != 0 || zoneid != ALL_ZONES);
	/*
	 * 1) MATCH_IRE_WQ : Used specifically to match on ire_stq.
	 *    The fast path update uses this to make sure it does not
	 *    update the fast path header of interface X with the fast
	 *    path updates it recieved on interface Y.  It is similar
	 *    in handling DL_NOTE_FASTPATH_FLUSH.
	 *
	 * 2) MATCH_IRE_ILL/MATCH_IRE_ILL_GROUP : We match both on ill
	 *    pointed by ire_stq and ire_ipif. Only in the case of
	 *    IRE_CACHEs can ire_stq and ire_ipif be pointing to
	 *    different ills. But we want to keep this function generic
	 *    enough for future use. So, we always try to match on both.
	 *    The only caller of this function ire_walk_ill_tables, will
	 *    call "func" after we return from this function. We expect
	 *    "func" to do the right filtering of ires in this case.
	 *
	 * NOTE : In the case of MATCH_IRE_ILL_GROUP, groups
	 * pointed by ire_stq and ire_ipif should always be the same.
	 * So, we just match on only one of them.
	 */
	if (match_flags & (MATCH_IRE_ILL|MATCH_IRE_ILL_GROUP)) {
		if (ire->ire_stq != NULL)
			ire_stq_ill = (ill_t *)ire->ire_stq->q_ptr;
		if (ire->ire_ipif != NULL)
			ire_ipif_ill = ire->ire_ipif->ipif_ill;
		if (ire_stq_ill != NULL)
			ire_ill_group = ire_stq_ill->ill_group;
		if ((ire_ill_group == NULL) && (ire_ipif_ill != NULL))
			ire_ill_group = ire_ipif_ill->ill_group;
	}

	if (zoneid != ALL_ZONES) {
		/*
		 * We're walking the IREs for a specific zone. The only relevant
		 * IREs are:
		 * - all IREs with a matching ire_zoneid
		 * - all IRE_OFFSUBNETs as they're shared across all zones
		 * - IRE_INTERFACE IREs for interfaces with a usable source addr
		 *   with a matching zone
		 * - IRE_DEFAULTs with a gateway reachable from the zone
		 * We should really match on IRE_OFFSUBNETs and IRE_DEFAULTs
		 * using the same rule; but the above rules are consistent with
		 * the behavior of ire_ftable_lookup[_v6]() so that all the
		 * routes that can be matched during lookup are also matched
		 * here.
		 */
		if (zoneid != ire->ire_zoneid) {
			/*
			 * Note, IRE_INTERFACE can have the stq as NULL. For
			 * example, if the default multicast route is tied to
			 * the loopback address.
			 */
			if ((ire->ire_type & IRE_INTERFACE) &&
			    (ire->ire_stq != NULL)) {
				ire_stq_ill = (ill_t *)ire->ire_stq->q_ptr;
				if (ire->ire_ipversion == IPV4_VERSION) {
					if (!ipif_usesrc_avail(ire_stq_ill,
					    zoneid))
						/* No usable src addr in zone */
						return (B_FALSE);
				} else if (ire_stq_ill->ill_usesrc_ifindex
				    != 0) {
					/*
					 * For IPv6 use ipif_select_source_v6()
					 * so the right scope selection is done
					 */
					ipif_t *src_ipif;
					src_ipif =
					    ipif_select_source_v6(ire_stq_ill,
					    &ire->ire_addr_v6, B_FALSE,
					    IPV6_PREFER_SRC_DEFAULT,
					    zoneid);
					if (src_ipif != NULL) {
						ipif_refrele(src_ipif);
					} else {
						return (B_FALSE);
					}
				} else {
					return (B_FALSE);
				}

			} else if (!(ire->ire_type & IRE_OFFSUBNET)) {
				return (B_FALSE);
			}
		}

		/*
		 * Match all default routes from the global zone, irrespective
		 * of reachability.
		 */
		if (ire->ire_type == IRE_DEFAULT && zoneid != GLOBAL_ZONEID) {
			int ire_match_flags = 0;
			in6_addr_t gw_addr_v6;
			ire_t *rire;

			if (ire->ire_ipif != NULL) {
				ire_match_flags |= MATCH_IRE_ILL_GROUP;
			}
			if (ire->ire_ipversion == IPV4_VERSION) {
				rire = ire_route_lookup(ire->ire_gateway_addr,
				    0, 0, 0, ire->ire_ipif, NULL, zoneid,
				    ire_match_flags);
			} 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);
				rire = ire_route_lookup_v6(&gw_addr_v6,
				    NULL, NULL, 0, ire->ire_ipif, NULL, zoneid,
				    ire_match_flags);
			}
			if (rire == NULL) {
				return (B_FALSE);
			}
			ire_refrele(rire);
		}
	}

	if (((!(match_flags & MATCH_IRE_TYPE)) ||
		(ire->ire_type & ire_type)) &&
	    ((!(match_flags & MATCH_IRE_WQ)) ||
		(ire->ire_stq == ill->ill_wq)) &&
	    ((!(match_flags & MATCH_IRE_ILL)) ||
		(ire_stq_ill == ill || ire_ipif_ill == ill)) &&
	    ((!(match_flags & MATCH_IRE_ILL_GROUP)) ||
		(ire_stq_ill == ill) || (ire_ipif_ill == ill) ||
		(ire_ill_group != NULL &&
		ire_ill_group == ill->ill_group))) {
		return (B_TRUE);
	}
	return (B_FALSE);
}

/*
 * Walk the ftable and the ctable entries that match the ill.
 */
static void
ire_walk_ill_tables(uint_t match_flags, uint_t ire_type, pfv_t func,
    char *arg, size_t ftbl_sz, size_t htbl_sz, irb_t **ipftbl,
    size_t ctbl_sz, irb_t *ipctbl, ill_t *ill, zoneid_t zoneid)
{
	irb_t	*irb_ptr;
	irb_t	*irb;
	ire_t	*ire;
	int i, j;
	boolean_t ret;

	ASSERT((!(match_flags & (MATCH_IRE_WQ | MATCH_IRE_ILL |
	    MATCH_IRE_ILL_GROUP))) || (ill != NULL));
	ASSERT(!(match_flags & MATCH_IRE_TYPE) || (ire_type != 0));
	/*
	 * Optimize by not looking at the forwarding table if there
	 * is a MATCH_IRE_TYPE specified with no IRE_FORWARDTABLE
	 * specified in ire_type.
	 */
	if (!(match_flags & MATCH_IRE_TYPE) ||
	    ((ire_type & IRE_FORWARDTABLE) != 0)) {
		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);
					}
					if (ret)
						(*func)(ire, arg);
				}
				IRB_REFRELE(irb);
			}
		}
	}

	/*
	 * Optimize by not looking at the cache table if there
	 * is a MATCH_IRE_TYPE specified with no IRE_CACHETABLE
	 * specified in ire_type.
	 */
	if (!(match_flags & MATCH_IRE_TYPE) ||
	    ((ire_type & IRE_CACHETABLE) != 0)) {
		for (i = 0; i < ctbl_sz;  i++) {
			irb = &ipctbl[i];
			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);
				}
				if (ret)
					(*func)(ire, arg);
			}
			IRB_REFRELE(irb);
		}
	}
}

/*
 * This routine walks through the ill chain to find if there is any
 * ire linked to the ill's interface based forwarding table
 * The arg could be ill or mp. This routine is called when a ill goes
 * down/deleted or the 'ipv4_ire_srcif_status' report is printed.
 */
void
ire_walk_srcif_table_v4(pfv_t func, char *arg)
{
	irb_t   *irb;
	ire_t   *ire;
	ill_t	*ill, *next_ill;
	int	i;
	int	total_count;
	ill_walk_context_t ctx;

	/*
	 * Take care of ire's in other ill's per-interface forwarding
	 * table. Check if any ire in any of the ill's ill_srcif_table
	 * is pointing to this ill.
	 */
	mutex_enter(&ire_srcif_table_lock);
	if (ire_srcif_table_count == 0) {
		mutex_exit(&ire_srcif_table_lock);
		return;
	}
	mutex_exit(&ire_srcif_table_lock);

#ifdef DEBUG
	/* Keep accounting of all interface based table ires */
	total_count = 0;
	rw_enter(&ill_g_lock, RW_READER);
	ill = ILL_START_WALK_V4(&ctx);
	while (ill != NULL) {
		mutex_enter(&ill->ill_lock);
		total_count += ill->ill_srcif_refcnt;
		next_ill = ill_next(&ctx, ill);
		mutex_exit(&ill->ill_lock);
		ill = next_ill;
	}
	rw_exit(&ill_g_lock);

	/* Hold lock here to make sure ire_srcif_table_count is stable */
	mutex_enter(&ire_srcif_table_lock);
	i = ire_srcif_table_count;
	mutex_exit(&ire_srcif_table_lock);
	ip1dbg(("ire_walk_srcif_v4: ire_srcif_table_count %d "
	    "total ill_srcif_refcnt %d\n", i, total_count));
#endif
	rw_enter(&ill_g_lock, RW_READER);
	ill = ILL_START_WALK_V4(&ctx);
	while (ill != NULL) {
		mutex_enter(&ill->ill_lock);
		if ((ill->ill_srcif_refcnt == 0) || !ILL_CAN_LOOKUP(ill)) {
			next_ill = ill_next(&ctx, ill);
			mutex_exit(&ill->ill_lock);
			ill = next_ill;
			continue;
		}
		ill_refhold_locked(ill);
		mutex_exit(&ill->ill_lock);
		rw_exit(&ill_g_lock);
		if (ill->ill_srcif_table != NULL) {
			for (i = 0; i < IP_SRCIF_TABLE_SIZE; i++) {
				irb = &(ill->ill_srcif_table[i]);
				if (irb->irb_ire == NULL)
					continue;
				IRB_REFHOLD(irb);
				for (ire = irb->irb_ire; ire != NULL;
				    ire = ire->ire_next) {
					(*func)(ire, arg);
				}
				IRB_REFRELE(irb);
			}
		}
		rw_enter(&ill_g_lock, RW_READER);
		next_ill = ill_next(&ctx, ill);
		ill_refrele(ill);
		ill = next_ill;
	}
	rw_exit(&ill_g_lock);
}

/*
 * 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)
{
	return (htonl(IP_HOST_MASK << (IP_ABITS - masklen)));
}

void
ire_atomic_end(irb_t *irb_ptr, ire_t *ire)
{
	ill_t	*ill_list[NUM_ILLS];

	ill_list[0] = ire->ire_stq != NULL ? ire->ire_stq->q_ptr : NULL;
	ill_list[1] = ire->ire_ipif != NULL ? ire->ire_ipif->ipif_ill : NULL;
	ill_list[2] = ire->ire_in_ill;
	ill_unlock_ills(ill_list, NUM_ILLS);
	rw_exit(&irb_ptr->irb_lock);
	rw_exit(&ill_g_usesrc_lock);
}

/*
 * ire_add_v[46] atomically make sure that the ipif or ill associated
 * with the new ire being added is stable and not IPIF_CHANGING or ILL_CHANGING
 * before adding the ire to the table. This ensures that we don't create
 * new IRE_CACHEs with stale values for parameters that are passed to
 * ire_create such as ire_max_frag. Note that ire_create() is passed a pointer
 * to the ipif_mtu, and not the value. The actual value is derived from the
 * parent ire or ipif under the bucket lock.
 */
int
ire_atomic_start(irb_t *irb_ptr, ire_t *ire, queue_t *q, mblk_t *mp,
    ipsq_func_t func)
{
	ill_t	*stq_ill;
	ill_t	*ipif_ill;
	ill_t	*in_ill;
	ill_t	*ill_list[NUM_ILLS];
	int	cnt = NUM_ILLS;
	int	error = 0;
	ill_t	*ill = NULL;

	ill_list[0] = stq_ill = ire->ire_stq !=
		NULL ? ire->ire_stq->q_ptr : NULL;
	ill_list[1] = ipif_ill = ire->ire_ipif !=
		NULL ? ire->ire_ipif->ipif_ill : NULL;
	ill_list[2] = in_ill = ire->ire_in_ill;

	ASSERT((q != NULL && mp != NULL && func != NULL) ||
	    (q == NULL && mp == NULL && func == NULL));
	rw_enter(&ill_g_usesrc_lock, RW_READER);
	GRAB_CONN_LOCK(q);
	rw_enter(&irb_ptr->irb_lock, RW_WRITER);
	ill_lock_ills(ill_list, cnt);

	/*
	 * While the IRE is in the process of being added, a user may have
	 * invoked the ifconfig usesrc option on the stq_ill to make it a
	 * usesrc client ILL. Check for this possibility here, if it is true
	 * then we fail adding the IRE_CACHE. Another check is to make sure
	 * that an ipif_ill of an IRE_CACHE being added is not part of a usesrc
	 * group. The ill_g_usesrc_lock is released in ire_atomic_end
	 */
	if ((ire->ire_type & IRE_CACHE) &&
	    (ire->ire_marks & IRE_MARK_USESRC_CHECK)) {
		if (stq_ill->ill_usesrc_ifindex != 0) {
			ASSERT(stq_ill->ill_usesrc_grp_next != NULL);
			if ((ipif_ill->ill_phyint->phyint_ifindex !=
			    stq_ill->ill_usesrc_ifindex) ||
			    (ipif_ill->ill_usesrc_grp_next == NULL) ||
			    (ipif_ill->ill_usesrc_ifindex != 0)) {
				error = EINVAL;
				goto done;
			}
		} else if (ipif_ill->ill_usesrc_grp_next != NULL) {
			error = EINVAL;
			goto done;
		}
	}

	/*
	 * IPMP flag settings happen without taking the exclusive route
	 * in ip_sioctl_flags. So we need to make an atomic check here
	 * for FAILED/OFFLINE/INACTIVE flags or if it has hit the
	 * FAILBACK=no case.
	 */
	if ((stq_ill != NULL) && !IAM_WRITER_ILL(stq_ill)) {
		if (stq_ill->ill_state_flags & ILL_CHANGING) {
			ill = stq_ill;
			error = EAGAIN;
		} else if ((stq_ill->ill_phyint->phyint_flags & PHYI_OFFLINE) ||
		    (ill_is_probeonly(stq_ill) &&
		    !(ire->ire_marks & IRE_MARK_HIDDEN))) {
			error = EINVAL;
		}
		goto done;
	}

	/*
	 * We don't check for OFFLINE/FAILED in this case because
	 * the source address selection logic (ipif_select_source)
	 * may still select a source address from such an ill. The
	 * assumption is that these addresses will be moved by in.mpathd
	 * soon. (i.e. this is a race). However link local addresses
	 * will not move and hence ipif_select_source_v6 tries to avoid
	 * FAILED ills. Please see ipif_select_source_v6 for more info
	 */
	if ((ipif_ill != NULL) && !IAM_WRITER_ILL(ipif_ill) &&
	    (ipif_ill->ill_state_flags & ILL_CHANGING)) {
		ill = ipif_ill;
		error = EAGAIN;
		goto done;
	}

	if ((in_ill != NULL) && !IAM_WRITER_ILL(in_ill) &&
	    (in_ill->ill_state_flags & ILL_CHANGING)) {
		ill = in_ill;
		error = EAGAIN;
		goto done;
	}

	if ((ire->ire_ipif != NULL) && !IAM_WRITER_IPIF(ire->ire_ipif) &&
	    (ire->ire_ipif->ipif_state_flags & IPIF_CHANGING)) {
		ill = ire->ire_ipif->ipif_ill;
		ASSERT(ill != NULL);
		error = EAGAIN;
		goto done;
	}

done:
	if (error == EAGAIN && ILL_CAN_WAIT(ill, q)) {
		ipsq_t *ipsq = ill->ill_phyint->phyint_ipsq;
		mutex_enter(&ipsq->ipsq_lock);
		ire_atomic_end(irb_ptr, ire);
		ipsq_enq(ipsq, q, mp, func, NEW_OP, ill);
		mutex_exit(&ipsq->ipsq_lock);
		error = EINPROGRESS;
	} else if (error != 0) {
		ire_atomic_end(irb_ptr, ire);
	}

	RELEASE_CONN_LOCK(q);
	return (error);
}

/*
 * Add a fully initialized IRE to an appropriate table based on
 * ire_type.
 */
int
ire_add(ire_t **irep, queue_t *q, mblk_t *mp, ipsq_func_t func)
{
	ire_t	*ire1;
	ill_t	*stq_ill = NULL;
	ill_t	*ill;
	ipif_t	*ipif = NULL;
	ill_walk_context_t ctx;
	ire_t	*ire = *irep;
	int	error;

	ASSERT(ire->ire_type != IRE_MIPRTUN);

	/* get ready for the day when original ire is not created as mblk */
	if (ire->ire_mp != NULL) {
		/* Copy the ire to a kmem_alloc'ed area */
		ire1 = kmem_cache_alloc(ire_cache, KM_NOSLEEP);
		if (ire1 == NULL) {
			ip1dbg(("ire_add: alloc failed\n"));
			ire_delete(ire);
			*irep = NULL;
			return (ENOMEM);
		}
		*ire1 = *ire;
		ire1->ire_mp = NULL;
		freeb(ire->ire_mp);
		ire = ire1;
	}
	if (ire->ire_stq != NULL)
		stq_ill = (ill_t *)ire->ire_stq->q_ptr;

	if (ire->ire_type == IRE_CACHE) {
		/*
		 * If this interface is FAILED, or INACTIVE or has hit
		 * the FAILBACK=no case, we create IRE_CACHES marked
		 * HIDDEN for some special cases e.g. bind to
		 * IPIF_NOFAILOVER address etc. So, if this interface
		 * is FAILED/INACTIVE/hit FAILBACK=no case, and we are
		 * not creating hidden ires, we should not allow that.
		 * This happens because the state of the interface
		 * changed while we were waiting in ARP. If this is the
		 * daemon sending probes, the next probe will create
		 * HIDDEN ires and we will create an ire then. This
		 * cannot happen with NDP currently because IRE is
		 * never queued in NDP. But it can happen in the
		 * future when we have external resolvers with IPv6.
		 * If the interface gets marked with OFFLINE while we
		 * are waiting in ARP, don't add the ire.
		 */
		if ((stq_ill->ill_phyint->phyint_flags & PHYI_OFFLINE) ||
		    (ill_is_probeonly(stq_ill) &&
		    !(ire->ire_marks & IRE_MARK_HIDDEN))) {
			/*
			 * We don't know whether it is a valid ipif or not.
			 * unless we do the check below. So, set it to NULL.
			 */
			ire->ire_ipif = NULL;
			ire_delete(ire);
			*irep = NULL;
			return (EINVAL);
		}
	}

	if (stq_ill != NULL && ire->ire_type == IRE_CACHE &&
	    stq_ill->ill_net_type == IRE_IF_RESOLVER) {
		rw_enter(&ill_g_lock, RW_READER);
		ill = ILL_START_WALK_ALL(&ctx);
		for (; ill != NULL; ill = ill_next(&ctx, ill)) {
			mutex_enter(&ill->ill_lock);
			if (ill->ill_state_flags & ILL_CONDEMNED) {
				mutex_exit(&ill->ill_lock);
				continue;
			}
			/*
			 * We need to make sure that the ipif is a valid one
			 * before adding the IRE_CACHE. This happens only
			 * with IRE_CACHE when there is an external resolver.
			 *
			 * We can unplumb a logical interface while the
			 * packet is waiting in ARP with the IRE. Then,
			 * later on when we feed the IRE back, the ipif
			 * has to be re-checked. This can't happen with
			 * NDP currently, as we never queue the IRE with
			 * the packet. We always try to recreate the IRE
			 * when the resolution is completed. But, we do
			 * it for IPv6 also here so that in future if
			 * we have external resolvers, it will work without
			 * any change.
			 */
			ipif = ipif_lookup_seqid(ill, ire->ire_ipif_seqid);
			if (ipif != NULL) {
				ipif_refhold_locked(ipif);
				mutex_exit(&ill->ill_lock);
				break;
			}
			mutex_exit(&ill->ill_lock);
		}
		rw_exit(&ill_g_lock);
		if (ipif == NULL ||
		    (ipif->ipif_isv6 &&
		    !IN6_ARE_ADDR_EQUAL(&ire->ire_src_addr_v6,
		    &ipif->ipif_v6src_addr)) ||
		    (!ipif->ipif_isv6 &&
		    ire->ire_src_addr != ipif->ipif_src_addr) ||
		    (ire->ire_zoneid != ipif->ipif_zoneid)) {

			if (ipif != NULL)
				ipif_refrele(ipif);
			ire->ire_ipif = NULL;
			ire_delete(ire);
			*irep = NULL;
			return (EINVAL);
		}


		ASSERT(ill != NULL);
		/*
		 * If this group was dismantled while this packets was
		 * queued in ARP, don't add it here.
		 */
		if (ire->ire_ipif->ipif_ill->ill_group != ill->ill_group) {
			/* We don't want ire_inactive bump stats for this */
			ipif_refrele(ipif);
			ire->ire_ipif = NULL;
			ire_delete(ire);
			*irep = NULL;
			return (EINVAL);
		}
	}

	/*
	 * In case ire was changed
	 */
	*irep = ire;
	if (ire->ire_ipversion == IPV6_VERSION) {
		error = ire_add_v6(irep, q, mp, func);
	} else {
		if (ire->ire_in_ill == NULL)
			error = ire_add_v4(irep, q, mp, func);
		else
			error = ire_add_srcif_v4(irep, q, mp, func);
	}
	if (ipif != NULL)
		ipif_refrele(ipif);
	return (error);
}

/*
 * Add a fully initialized IRE to an appropriate
 * table based on ire_type.
 *
 * The forward table contains IRE_PREFIX/IRE_HOST/IRE_HOST_REDIRECT
 * IRE_IF_RESOLVER/IRE_IF_NORESOLVER and IRE_DEFAULT.
 *
 * The cache table contains IRE_BROADCAST/IRE_LOCAL/IRE_LOOPBACK
 * and IRE_CACHE.
 *
 * NOTE : This function is called as writer though not required
 * by this function.
 */
static int
ire_add_v4(ire_t **ire_p, queue_t *q, mblk_t *mp, ipsq_func_t func)
{
	ire_t	*ire1;
	int	mask_table_index;
	irb_t	*irb_ptr;
	ire_t	**irep;
	int	flags;
	ire_t	*pire = NULL;
	ill_t	*stq_ill;
	ire_t	*ire = *ire_p;
	int	error;

	if (ire->ire_ipif != NULL)
		ASSERT(!MUTEX_HELD(&ire->ire_ipif->ipif_ill->ill_lock));
	if (ire->ire_stq != NULL)
		ASSERT(!MUTEX_HELD(
		    &((ill_t *)(ire->ire_stq->q_ptr))->ill_lock));
	ASSERT(ire->ire_ipversion == IPV4_VERSION);
	ASSERT(ire->ire_mp == NULL); /* Calls should go through ire_add */
	ASSERT(ire->ire_in_ill == NULL); /* No srcif entries */

	/* Find the appropriate list head. */
	switch (ire->ire_type) {
	case IRE_HOST:
		ire->ire_mask = IP_HOST_MASK;
		ire->ire_masklen = IP_ABITS;
		if ((ire->ire_flags & RTF_SETSRC) == 0)
			ire->ire_src_addr = 0;
		break;
	case IRE_HOST_REDIRECT:
		ire->ire_mask = IP_HOST_MASK;
		ire->ire_masklen = IP_ABITS;
		ire->ire_src_addr = 0;
		break;
	case IRE_CACHE:
	case IRE_BROADCAST:
	case IRE_LOCAL:
	case IRE_LOOPBACK:
		ire->ire_mask = IP_HOST_MASK;
		ire->ire_masklen = IP_ABITS;
		break;
	case IRE_PREFIX:
		if ((ire->ire_flags & RTF_SETSRC) == 0)
			ire->ire_src_addr = 0;
		break;
	case IRE_DEFAULT:
		if ((ire->ire_flags & RTF_SETSRC) == 0)
			ire->ire_src_addr = 0;
		break;
	case IRE_IF_RESOLVER:
	case IRE_IF_NORESOLVER:
		break;
	default:
		printf("ire_add_v4: ire %p has unrecognized IRE type (%d)\n",
		    (void *)ire, ire->ire_type);
		ire_delete(ire);
		*ire_p = NULL;
		return (EINVAL);
	}

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

	if ((ire->ire_type & IRE_CACHETABLE) == 0) {
		/* IRE goes into Forward Table */
		mask_table_index = ire->ire_masklen;
		if ((ip_forwarding_table[mask_table_index]) == NULL) {
			irb_t *ptr;
			int i;

			ptr = (irb_t *)mi_zalloc((ip_ftable_hash_size *
			    sizeof (irb_t)));
			if (ptr == NULL) {
				ire_delete(ire);
				*ire_p = NULL;
				return (ENOMEM);
			}
			for (i = 0; i < ip_ftable_hash_size; i++) {
				rw_init(&ptr[i].irb_lock, NULL,
				    RW_DEFAULT, NULL);
			}
			mutex_enter(&ire_ft_init_lock);
			if (ip_forwarding_table[mask_table_index] == NULL) {
				ip_forwarding_table[mask_table_index] = ptr;
				mutex_exit(&ire_ft_init_lock);
			} else {
				/*
				 * Some other thread won the race in
				 * initializing the forwarding table at the
				 * same index.
				 */
				mutex_exit(&ire_ft_init_lock);
				for (i = 0; i < ip_ftable_hash_size; i++) {
					rw_destroy(&ptr[i].irb_lock);
				}
				mi_free(ptr);
			}
		}
		irb_ptr = &(ip_forwarding_table[mask_table_index][
		    IRE_ADDR_HASH(ire->ire_addr, ip_ftable_hash_size)]);
	} else {
		irb_ptr = &(ip_cache_table[IRE_ADDR_HASH(ire->ire_addr,
		    ip_cache_table_size)]);
	}
	/*
	 * ip_newroute/ip_newroute_multi are unable to prevent the deletion
	 * of the interface route while adding an IRE_CACHE for an on-link
	 * destination in the IRE_IF_RESOLVER case, since the ire has to
	 * go to ARP and return. We can't do a REFHOLD on the
	 * associated interface ire for fear of ARP freeing the message.
	 * Here we look up the interface ire in the forwarding table and
	 * make sure that the interface route has not been deleted.
	 */
	if (ire->ire_type == IRE_CACHE && ire->ire_gateway_addr == 0 &&
	    ((ill_t *)ire->ire_stq->q_ptr)->ill_net_type == IRE_IF_RESOLVER) {
		ASSERT(ire->ire_max_fragp == NULL);
		if (CLASSD(ire->ire_addr) && !(ire->ire_flags & RTF_SETSRC)) {
			/*
			 * The ihandle that we used in ip_newroute_multi
			 * comes from the interface route corresponding
			 * to ire_ipif. Lookup here to see if it exists
			 * still.
			 * If the ire has a source address assigned using
			 * RTF_SETSRC, ire_ipif is the logical interface holding
			 * this source address, so we can't use it to check for
			 * the existence of the interface route. Instead we rely
			 * on the brute force ihandle search in
			 * ire_ihandle_lookup_onlink() below.
			 */
			pire = ipif_to_ire(ire->ire_ipif);
			if (pire == NULL) {
				ire_delete(ire);
				*ire_p = NULL;
				return (EINVAL);
			} else if (pire->ire_ihandle != ire->ire_ihandle) {
				ire_refrele(pire);
				ire_delete(ire);
				*ire_p = NULL;
				return (EINVAL);
			}
		} else {
			pire = ire_ihandle_lookup_onlink(ire);
			if (pire == NULL) {
				ire_delete(ire);
				*ire_p = NULL;
				return (EINVAL);
			}
		}
		/* Prevent pire from getting deleted */
		IRB_REFHOLD(pire->ire_bucket);
		/* Has it been removed already ? */
		if (pire->ire_marks & IRE_MARK_CONDEMNED) {
			IRB_REFRELE(pire->ire_bucket);
			ire_refrele(pire);
			ire_delete(ire);
			*ire_p = NULL;
			return (EINVAL);
		}
	} else {
		ASSERT(ire->ire_max_fragp != NULL);
	}
	flags = (MATCH_IRE_MASK | MATCH_IRE_TYPE | MATCH_IRE_GW);

	if (ire->ire_ipif != NULL) {
		/*
		 * We use MATCH_IRE_IPIF while adding IRE_CACHES only
		 * for historic reasons and to maintain symmetry with
		 * IPv6 code path. Historically this was used by
		 * multicast code to create multiple IRE_CACHES on
		 * a single ill with different ipifs. This was used
		 * so that multicast packets leaving the node had the
		 * right source address. This is no longer needed as
		 * ip_wput initializes the address correctly.
		 */
		flags |= MATCH_IRE_IPIF;
		/*
		 * If we are creating hidden ires, make sure we search on
		 * this ill (MATCH_IRE_ILL) and a hidden ire,
		 * while we are searching for duplicates below. Otherwise we
		 * could potentially find an IRE on some other interface
		 * and it may not be a IRE marked with IRE_MARK_HIDDEN. We
		 * shouldn't do this as this will lead to an infinite loop
		 * (if we get to ip_wput again) eventually we need an hidden
		 * ire for this packet to go out. MATCH_IRE_ILL is explicitly
		 * done below.
		 */
		if (ire->ire_type == IRE_CACHE &&
		    (ire->ire_marks & IRE_MARK_HIDDEN))
			flags |= (MATCH_IRE_MARK_HIDDEN);
	}

	/*
	 * Start the atomic add of the ire. Grab the ill locks,
	 * ill_g_usesrc_lock and the bucket lock. Check for condemned
	 *
	 * If ipif or ill is changing ire_atomic_start() may queue the
	 * request and return EINPROGRESS.
	 */
	error = ire_atomic_start(irb_ptr, ire, q, mp, func);
	if (error != 0) {
		/*
		 * We don't know whether it is a valid ipif or not.
		 * So, set it to NULL. This assumes that the ire has not added
		 * a reference to the ipif.
		 */
		ire->ire_ipif = NULL;
		ire_delete(ire);
		if (pire != NULL) {
			IRB_REFRELE(pire->ire_bucket);
			ire_refrele(pire);
		}
		*ire_p = NULL;
		return (error);
	}
	/*
	 * To avoid creating ires having stale values for the ire_max_frag
	 * we get the latest value atomically here. For more details
	 * see the block comment in ip_sioctl_mtu and in DL_NOTE_SDU_CHANGE
	 * in ip_rput_dlpi_writer
	 */
	if (ire->ire_max_fragp == NULL) {
		if (CLASSD(ire->ire_addr))
			ire->ire_max_frag = ire->ire_ipif->ipif_mtu;
		else
			ire->ire_max_frag = pire->ire_max_frag;
	} else {
		uint_t	max_frag;

		max_frag = *ire->ire_max_fragp;
		ire->ire_max_fragp = NULL;
		ire->ire_max_frag = max_frag;
	}
	/*
	 * Atomically check for duplicate and insert in the table.
	 */
	for (ire1 = irb_ptr->irb_ire; ire1 != NULL; ire1 = ire1->ire_next) {
		if (ire1->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		if (ire->ire_ipif != NULL) {
			/*
			 * We do MATCH_IRE_ILL implicitly here for IREs
			 * with a non-null ire_ipif, including IRE_CACHEs.
			 * As ire_ipif and ire_stq could point to two
			 * different ills, we can't pass just ire_ipif to
			 * ire_match_args and get a match on both ills.
			 * This is just needed for duplicate checks here and
			 * so we don't add an extra argument to
			 * ire_match_args for this. Do it locally.
			 *
			 * NOTE : Currently there is no part of the code
			 * that asks for both MATH_IRE_IPIF and MATCH_IRE_ILL
			 * match for IRE_CACHEs. Thus we don't want to
			 * extend the arguments to ire_match_args.
			 */
			if (ire1->ire_stq != ire->ire_stq)
				continue;
			/*
			 * Multiroute IRE_CACHEs for a given destination can
			 * have the same ire_ipif, typically if their source
			 * address is forced using RTF_SETSRC, and the same
			 * send-to queue. We differentiate them using the parent
			 * handle.
			 */
			if (ire->ire_type == IRE_CACHE &&
			    (ire1->ire_flags & RTF_MULTIRT) &&
			    (ire->ire_flags & RTF_MULTIRT) &&
			    (ire1->ire_phandle != ire->ire_phandle))
				continue;
		}
		if (ire1->ire_zoneid != ire->ire_zoneid)
			continue;
		if (ire_match_args(ire1, ire->ire_addr, ire->ire_mask,
		    ire->ire_gateway_addr, ire->ire_type, ire->ire_ipif,
		    ire->ire_zoneid, 0, 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.
			 */
			ip1dbg(("found dup ire existing %p new %p",
			    (void *)ire1, (void *)ire));
			IRE_REFHOLD(ire1);
			ire_atomic_end(irb_ptr, ire);
			ire_delete(ire);
			if (pire != NULL) {
				/*
				 * Assert that it is not removed from the
				 * list yet.
				 */
				ASSERT(pire->ire_ptpn != NULL);
				IRB_REFRELE(pire->ire_bucket);
				ire_refrele(pire);
			}
			*ire_p = ire1;
			return (0);
		}
	}

	/*
	 * Make it easy for ip_wput_ire() to hit multiple broadcast ires by
	 * grouping identical addresses together on the hash chain. We also
	 * don't want to send multiple copies out if there are two ills part
	 * of the same group. Thus we group the ires with same addr and same
	 * ill group together so that ip_wput_ire can easily skip all the
	 * ires with same addr and same group after sending the first copy.
	 * We do this only for IRE_BROADCASTs as ip_wput_ire is currently
	 * interested in such groupings only for broadcasts.
	 *
	 * NOTE : If the interfaces are brought up first and then grouped,
	 * illgrp_insert will handle it. We come here when the interfaces
	 * are already in group and we are bringing them UP.
	 *
	 * Find the first entry that matches ire_addr. *irep will be null
	 * if no match.
	 */
	irep = (ire_t **)irb_ptr;
	while ((ire1 = *irep) != NULL && ire->ire_addr != ire1->ire_addr)
		irep = &ire1->ire_next;
	if (ire->ire_type == IRE_BROADCAST && *irep != NULL) {
		/*
		 * We found some ire (i.e *irep) with a matching addr. We
		 * want to group ires with same addr and same ill group
		 * together.
		 *
		 * First get to the entry that matches our address and
		 * ill group i.e stop as soon as we find the first ire
		 * matching the ill group and address. If there is only
		 * an address match, we should walk and look for some
		 * group match. These are some of the possible scenarios :
		 *
		 * 1) There are no groups at all i.e all ire's ill_group
		 *    are NULL. In that case we will essentially group
		 *    all the ires with the same addr together. Same as
		 *    the "else" block of this "if".
		 *
		 * 2) There are some groups and this ire's ill_group is
		 *    NULL. In this case, we will first find the group
		 *    that matches the address and a NULL group. Then
		 *    we will insert the ire at the end of that group.
		 *
		 * 3) There are some groups and this ires's ill_group is
		 *    non-NULL. In this case we will first find the group
		 *    that matches the address and the ill_group. Then
		 *    we will insert the ire at the end of that group.
		 */
		/* LINTED : constant in conditional context */
		while (1) {
			ire1 = *irep;
			if ((ire1->ire_next == NULL) ||
			    (ire1->ire_next->ire_addr != ire->ire_addr) ||
			    (ire1->ire_type != IRE_BROADCAST) ||
			    (ire1->ire_ipif->ipif_ill->ill_group ==
			    ire->ire_ipif->ipif_ill->ill_group))
				break;
			irep = &ire1->ire_next;
		}
		ASSERT(*irep != NULL);
		irep = &((*irep)->ire_next);

		/*
		 * Either we have hit the end of the list or the address
		 * did not match or the group *matched*. If we found
		 * a match on the group, skip to the end of the group.
		 */
		while (*irep != NULL) {
			ire1 = *irep;
			if ((ire1->ire_addr != ire->ire_addr) ||
			    (ire1->ire_type != IRE_BROADCAST) ||
			    (ire1->ire_ipif->ipif_ill->ill_group !=
			    ire->ire_ipif->ipif_ill->ill_group))
				break;
			if (ire1->ire_ipif->ipif_ill->ill_group == NULL &&
			    ire1->ire_ipif == ire->ire_ipif) {
				irep = &ire1->ire_next;
				break;
			}
			irep = &ire1->ire_next;
		}
	} else if (*irep != NULL) {
		/*
		 * Find the last ire which matches ire_addr.
		 * Needed to do tail insertion among entries with the same
		 * ire_addr.
		 */
		while (ire->ire_addr == ire1->ire_addr) {
			irep = &ire1->ire_next;
			ire1 = *irep;
			if (ire1 == NULL)
				break;
		}
	}

	if (ire->ire_type == IRE_DEFAULT) {
		/*
		 * We keep a count of default gateways which is used when
		 * assigning them as routes.
		 */
		ip_ire_default_count++;
		ASSERT(ip_ire_default_count != 0); /* Wraparound */
	}
	/* 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(ire_stats_v4, ire_stats_inserted);
	irb_ptr->irb_ire_cnt++;
	if (ire->ire_marks & IRE_MARK_TEMPORARY)
		irb_ptr->irb_tmp_ire_cnt++;

	if (ire->ire_ipif != NULL) {
		ire->ire_ipif->ipif_ire_cnt++;
		if (ire->ire_stq != NULL) {
			stq_ill = (ill_t *)ire->ire_stq->q_ptr;
			stq_ill->ill_ire_cnt++;
		}
	} else {
		ASSERT(ire->ire_stq == NULL);
	}

	ire_atomic_end(irb_ptr, ire);

	if (pire != NULL) {
		/* Assert that it is not removed from the list yet */
		ASSERT(pire->ire_ptpn != NULL);
		IRB_REFRELE(pire->ire_bucket);
		ire_refrele(pire);
	}

	if (ire->ire_type != IRE_CACHE) {
		/*
		 * For ire's with with host mask see if there is an entry
		 * in the cache. If there is one flush the whole cache as
		 * there might be multiple entries due to RTF_MULTIRT (CGTP).
		 * If no entry is found than there is no need to flush the
		 * cache.
		 */
		if (ire->ire_mask == IP_HOST_MASK) {
			ire_t *lire;
			lire = ire_ctable_lookup(ire->ire_addr, NULL, IRE_CACHE,
			    NULL, ALL_ZONES, MATCH_IRE_TYPE);
			if (lire != NULL) {
				ire_refrele(lire);
				ire_flush_cache_v4(ire, IRE_FLUSH_ADD);
			}
		} else {
			ire_flush_cache_v4(ire, IRE_FLUSH_ADD);
		}
	}
	/*
	 * We had to delay the fast path probe until the ire is inserted
	 * in the list. Otherwise the fast path ack won't find the ire in
	 * the table.
	 */
	if (ire->ire_type == IRE_CACHE || ire->ire_type == IRE_BROADCAST)
		ire_fastpath(ire);
	if (ire->ire_ipif != NULL)
		ASSERT(!MUTEX_HELD(&ire->ire_ipif->ipif_ill->ill_lock));
	*ire_p = ire;
	return (0);
}

/*
 * Search for all HOST REDIRECT routes that are
 * pointing at the specified gateway and
 * delete them. This routine is called only
 * when a default gateway is going away.
 */
static void
ire_delete_host_redirects(ipaddr_t gateway)
{
	irb_t *irb_ptr;
	irb_t *irb;
	ire_t *ire;
	int i;

	/* get the hash table for HOST routes */
	irb_ptr = ip_forwarding_table[(IP_MASK_TABLE_SIZE - 1)];
	if (irb_ptr == NULL)
		return;
	for (i = 0; (i < ip_ftable_hash_size); i++) {
		irb = &irb_ptr[i];
		IRB_REFHOLD(irb);
		for (ire = irb->irb_ire; ire != NULL; ire = ire->ire_next) {
			if (ire->ire_type != IRE_HOST_REDIRECT)
				continue;
			if (ire->ire_gateway_addr == gateway) {
				ire_delete(ire);
			}
		}
		IRB_REFRELE(irb);
	}
}

/*
 * 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;

	ASSERT(ire != NULL);

	while (ire != NULL) {
		ire_next = ire->ire_next;
		if (ire->ire_ipversion == IPV4_VERSION) {
			ire_delete_v4(ire);
			BUMP_IRE_STATS(ire_stats_v4, ire_stats_deleted);
		} else {
			ASSERT(ire->ire_ipversion == IPV6_VERSION);
			ire_delete_v6(ire);
			BUMP_IRE_STATS(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_refcnt == 0);
	ASSERT(irb->irb_marks & IRE_MARK_CONDEMNED);
	ASSERT(irb->irb_ire != NULL);

	for (ire = irb->irb_ire; ire != NULL; ire = ire1) {
		ire1 = ire->ire_next;
		if (ire->ire_marks & IRE_MARK_CONDEMNED) {
			ptpn = ire->ire_ptpn;
			ire1 = ire->ire_next;
			if (ire1)
				ire1->ire_ptpn = ptpn;
			*ptpn = ire1;
			ire->ire_ptpn = NULL;
			ire->ire_next = NULL;
			if (ire->ire_type == IRE_DEFAULT) {
				/*
				 * IRE is out of the list. We need to adjust
				 * the accounting before the caller drops
				 * the lock.
				 */
				if (ire->ire_ipversion == IPV6_VERSION) {
					ASSERT(ipv6_ire_default_count != 0);
					ipv6_ire_default_count--;
				} else {
					ASSERT(ip_ire_default_count != 0);
					ip_ire_default_count--;
				}
			}
			/*
			 * We need to call ire_delete_v4 or ire_delete_v6
			 * to clean up the cache or 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;
		}
	}
	ASSERT(irb->irb_refcnt == 0);
	irb->irb_marks &= ~IRE_MARK_CONDEMNED;
	ASSERT(ire_list != NULL);
	return (ire_list);
}

/*
 * Delete all the cache entries with this 'addr'.  When IP gets a gratuitous
 * ARP message on any of its interface queue, it scans the cache table and
 * deletes all the cache entries for that address. This function is called
 * from ip_arp_news in ip.c and  also for ARP ioctl processing in ip_if.c.
 * ip_ire_clookup_and_delete returns true if it finds at least one cache entry
 * which is used by ip_arp_news to determine if it needs to do an ire_walk_v4.
 * The return value is also  used for the same purpose by ARP IOCTL processing
 * in ip_if.c when deleting ARP entries. For SIOC*IFARP ioctls in addition to
 * the address, ip_if->ipif_ill also needs to be matched.
 */
boolean_t
ip_ire_clookup_and_delete(ipaddr_t addr, ipif_t *ipif)
{
	irb_t		*irb;
	ire_t		*cire;
	ill_t		*ill;
	boolean_t	found = B_FALSE, loop_end = B_FALSE;

	irb = &ip_cache_table[IRE_ADDR_HASH(addr, ip_cache_table_size)];
	IRB_REFHOLD(irb);
	for (cire = irb->irb_ire; cire != NULL; cire = cire->ire_next) {
		if (cire->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		if (cire->ire_addr == addr) {

			/* This signifies start of an address match */
			if (!loop_end)
				loop_end = B_TRUE;

			/* We are interested only in IRE_CACHEs */
			if (cire->ire_type == IRE_CACHE) {
				/* If we want a match with the ILL */
				if (ipif != NULL &&
				    ((ill = ire_to_ill(cire)) == NULL ||
				    ill != ipif->ipif_ill)) {
					continue;
				}
				if (!found)
					found = B_TRUE;
				ire_delete(cire);
			}
		/* End of the match */
		} else if (loop_end)
			break;
	}
	IRB_REFRELE(irb);

	return (found);

}

/*
 * Delete the specified IRE.
 */
void
ire_delete(ire_t *ire)
{
	ire_t	*ire1;
	ire_t	**ptpn;
	irb_t *irb;

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

	rw_enter(&irb->irb_lock, RW_WRITER);

	/*
	 * In case of V4 we might still be waiting for fastpath ack.
	 */
	if (ire->ire_nce == NULL && ire->ire_stq != NULL) {
		ill_t *ill;

		ill = ire_to_ill(ire);
		if (ill != NULL)
			ire_fastpath_list_delete(ill, ire);
	}

	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 (irb->irb_refcnt != 0) {
		/*
		 * The last thread to leave this bucket will
		 * delete this ire.
		 */
		if (!(ire->ire_marks & IRE_MARK_CONDEMNED)) {
			irb->irb_ire_cnt--;
			if (ire->ire_marks & IRE_MARK_TEMPORARY)
				irb->irb_tmp_ire_cnt--;
			ire->ire_marks |= IRE_MARK_CONDEMNED;
		}
		irb->irb_marks |= IRE_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(ire_stats_v6, ire_stats_deleted);
	} else {
		BUMP_IRE_STATS(ire_stats_v4, ire_stats_deleted);
	}
	/*
	 * ip_wput/ip_wput_v6 checks this flag to see whether
	 * it should still use the cached ire or not.
	 */
	ire->ire_marks |= IRE_MARK_CONDEMNED;
	if (ire->ire_type == IRE_DEFAULT) {
		/*
		 * IRE is out of the list. We need to adjust the
		 * accounting before we drop the lock.
		 */
		if (ire->ire_ipversion == IPV6_VERSION) {
			ASSERT(ipv6_ire_default_count != 0);
			ipv6_ire_default_count--;
		} else {
			ASSERT(ip_ire_default_count != 0);
			ip_ire_default_count--;
		}
	}
	irb->irb_ire_cnt--;
	if (ire->ire_marks & IRE_MARK_TEMPORARY)
		irb->irb_tmp_ire_cnt--;
	rw_exit(&irb->irb_lock);

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

	if (ire->ire_type != IRE_CACHE)
		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);
	}
}

/*
 * IRE_REFRELE/ire_refrele are 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)
{
	mblk_t *mp;
	nce_t	*nce;
	ill_t	*ill = NULL;
	ill_t	*stq_ill = NULL;
	ill_t	*in_ill = NULL;
	ipif_t	*ipif;
	boolean_t	need_wakeup = B_FALSE;

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

	if ((nce = ire->ire_nce) != NULL) {
		/* Only IPv6 IRE_CACHE type has an nce */
		ASSERT(ire->ire_type == IRE_CACHE);
		ASSERT(ire->ire_ipversion == IPV6_VERSION);
		NCE_REFRELE_NOTR(nce);
		ire->ire_nce = NULL;
	}
	if (ire->ire_ipif == NULL)
		goto end;

	ipif = ire->ire_ipif;
	ill = ipif->ipif_ill;

	if (ire->ire_bucket == NULL) {
		/* The ire was never inserted in the table. */
		goto end;
	}

	/*
	 * ipif_ire_cnt on this ipif goes down by 1. If the ire_stq is
	 * non-null ill_ire_count also goes down by 1. If the in_ill is
	 * non-null either ill_mrtun_refcnt or ill_srcif_refcnt goes down by 1.
	 *
	 * The ipif that is associated with an ire is ire->ire_ipif and
	 * hence when the ire->ire_ipif->ipif_ire_cnt drops to zero we call
	 * ipif_ill_refrele_tail. Usually stq_ill is null or the same as
	 * ire->ire_ipif->ipif_ill. So nothing more needs to be done. Only
	 * in the case of IRE_CACHES when IPMP is used, stq_ill can be
	 * different. If this is different from ire->ire_ipif->ipif_ill and
	 * if the ill_ire_cnt on the stq_ill also has dropped to zero, we call
	 * ipif_ill_refrele_tail on the stq_ill. If mobile ip is in use
	 * in_ill could be non-null. If it is a reverse tunnel related ire
	 * ill_mrtun_refcnt is non-zero. If it is forward tunnel related ire
	 * ill_srcif_refcnt is non-null.
	 */

	if (ire->ire_stq != NULL)
		stq_ill = (ill_t *)ire->ire_stq->q_ptr;
	if (ire->ire_in_ill != NULL)
		in_ill = ire->ire_in_ill;

	if ((stq_ill == NULL || stq_ill == ill) && (in_ill == NULL)) {
		/* Optimize the most common case */
		mutex_enter(&ill->ill_lock);
		ASSERT(ipif->ipif_ire_cnt != 0);
		ipif->ipif_ire_cnt--;
		if (ipif->ipif_ire_cnt == 0)
			need_wakeup = B_TRUE;
		if (stq_ill != NULL) {
			ASSERT(stq_ill->ill_ire_cnt != 0);
			stq_ill->ill_ire_cnt--;
			if (stq_ill->ill_ire_cnt == 0)
				need_wakeup = B_TRUE;
		}
		if (need_wakeup) {
			/* Drops the ill lock */
			ipif_ill_refrele_tail(ill);
		} else {
			mutex_exit(&ill->ill_lock);
		}
	} else {
		/*
		 * We can't grab all the ill locks at the same time.
		 * It can lead to recursive lock enter in the call to
		 * ipif_ill_refrele_tail and later. Instead do it 1 at
		 * a time.
		 */
		mutex_enter(&ill->ill_lock);
		ASSERT(ipif->ipif_ire_cnt != 0);
		ipif->ipif_ire_cnt--;
		if (ipif->ipif_ire_cnt == 0) {
			/* Drops the lock */
			ipif_ill_refrele_tail(ill);
		} else {
			mutex_exit(&ill->ill_lock);
		}
		if (stq_ill != NULL) {
			mutex_enter(&stq_ill->ill_lock);
			ASSERT(stq_ill->ill_ire_cnt != 0);
			stq_ill->ill_ire_cnt--;
			if (stq_ill->ill_ire_cnt == 0)  {
				/* Drops the ill lock */
				ipif_ill_refrele_tail(stq_ill);
			} else {
				mutex_exit(&stq_ill->ill_lock);
			}
		}
		if (in_ill != NULL) {
			mutex_enter(&in_ill->ill_lock);
			if (ire->ire_type == IRE_MIPRTUN) {
				/*
				 * Mobile IP reverse tunnel ire.
				 * Decrement table count and the
				 * ill reference count. This signifies
				 * mipagent is deleting reverse tunnel
				 * route for a particular mobile node.
				 */
				mutex_enter(&ire_mrtun_lock);
				ire_mrtun_count--;
				mutex_exit(&ire_mrtun_lock);
				ASSERT(in_ill->ill_mrtun_refcnt != 0);
				in_ill->ill_mrtun_refcnt--;
				if (in_ill->ill_mrtun_refcnt == 0) {
					/* Drops the ill lock */
					ipif_ill_refrele_tail(in_ill);
				} else {
					mutex_exit(&in_ill->ill_lock);
				}
			} else {
				mutex_enter(&ire_srcif_table_lock);
				ire_srcif_table_count--;
				mutex_exit(&ire_srcif_table_lock);
				ASSERT(in_ill->ill_srcif_refcnt != 0);
				in_ill->ill_srcif_refcnt--;
				if (in_ill->ill_srcif_refcnt == 0) {
					/* Drops the ill lock */
					ipif_ill_refrele_tail(in_ill);
				} else {
					mutex_exit(&in_ill->ill_lock);
				}
			}
		}
	}
end:
	/* This should be true for both V4 and V6 */
	ASSERT(ire->ire_fastpath == NULL);


	ire->ire_ipif = NULL;

	/* Free the xmit header, and the IRE itself. */
	if ((mp = ire->ire_dlureq_mp) != NULL) {
		freeb(mp);
		ire->ire_dlureq_mp = NULL;
	}

	if ((mp = ire->ire_fp_mp) != NULL) {
		freeb(mp);
		ire->ire_fp_mp = NULL;
	}

	if (ire->ire_in_ill != NULL) {
		ire->ire_in_ill = NULL;
	}

#ifdef IRE_DEBUG
	ire_trace_inactive(ire);
#endif
	mutex_destroy(&ire->ire_lock);
	if (ire->ire_ipversion == IPV6_VERSION) {
		BUMP_IRE_STATS(ire_stats_v6, ire_stats_freed);
	} else {
		BUMP_IRE_STATS(ire_stats_v4, ire_stats_freed);
	}
	if (ire->ire_mp != NULL) {
		/* Still in an mblk */
		freeb(ire->ire_mp);
	} else {
		/* Has been allocated out of the cache */
		kmem_cache_free(ire_cache, ire);
	}
}

/*
 * ire_walk routine to delete all IRE_CACHE/IRE_HOST_REDIRECT entries
 * that have a given gateway address.
 */
void
ire_delete_cache_gw(ire_t *ire, char *cp)
{
	ipaddr_t	gw_addr;

	if (!(ire->ire_type & (IRE_CACHE|IRE_HOST_REDIRECT)))
		return;

	bcopy(cp, &gw_addr, sizeof (gw_addr));
	if (ire->ire_gateway_addr == gw_addr) {
		ip1dbg(("ire_delete_cache_gw: deleted 0x%x type %d to 0x%x\n",
			(int)ntohl(ire->ire_addr), ire->ire_type,
			(int)ntohl(ire->ire_gateway_addr)));
		ire_delete(ire);
	}
}

/*
 * Remove all IRE_CACHE entries that match the ire specified.
 *
 * The flag argument indicates if the flush request is due to addition
 * of new route (IRE_FLUSH_ADD) or deletion of old route (IRE_FLUSH_DELETE).
 *
 * This routine takes only the IREs from the forwarding table and flushes
 * the corresponding entries from the cache table.
 *
 * When flushing due to the deletion of an old route, it
 * just checks the cache handles (ire_phandle and ire_ihandle) and
 * deletes the ones that match.
 *
 * When flushing due to the creation of a new route, it checks
 * if a cache entry's address matches the one in the IRE and
 * that the cache entry's parent has a less specific mask than the
 * one in IRE. The destination of such a cache entry could be the
 * gateway for other cache entries, so we need to flush those as
 * well by looking for gateway addresses matching the IRE's address.
 */
void
ire_flush_cache_v4(ire_t *ire, int flag)
{
	int i;
	ire_t *cire;
	irb_t *irb;

	if (ire->ire_type & IRE_CACHE)
	    return;

	/*
	 * If a default is just created, there is no point
	 * in going through the cache, as there will not be any
	 * cached ires.
	 */
	if (ire->ire_type == IRE_DEFAULT && flag == IRE_FLUSH_ADD)
		return;
	if (flag == IRE_FLUSH_ADD) {
		/*
		 * This selective flush is due to the addition of
		 * new IRE.
		 */
		for (i = 0; i < ip_cache_table_size; i++) {
			irb = &ip_cache_table[i];
			if ((cire = irb->irb_ire) == NULL)
				continue;
			IRB_REFHOLD(irb);
			for (cire = irb->irb_ire; cire != NULL;
			    cire = cire->ire_next) {
				if (cire->ire_type != IRE_CACHE)
					continue;
				/*
				 * If 'cire' belongs to the same subnet
				 * as the new ire being added, and 'cire'
				 * is derived from a prefix that is less
				 * specific than the new ire being added,
				 * we need to flush 'cire'; for instance,
				 * when a new interface comes up.
				 */
				if (((cire->ire_addr & ire->ire_mask) ==
				    (ire->ire_addr & ire->ire_mask)) &&
				    (ip_mask_to_plen(cire->ire_cmask) <=
				    ire->ire_masklen)) {
					ire_delete(cire);
					continue;
				}
				/*
				 * This is the case when the ire_gateway_addr
				 * of 'cire' belongs to the same subnet as
				 * the new ire being added.
				 * Flushing such ires is sometimes required to
				 * avoid misrouting: say we have a machine with
				 * two interfaces (I1 and I2), a default router
				 * R on the I1 subnet, and a host route to an
				 * off-link destination D with a gateway G on
				 * the I2 subnet.
				 * Under normal operation, we will have an
				 * on-link cache entry for G and an off-link
				 * cache entry for D with G as ire_gateway_addr,
				 * traffic to D will reach its destination
				 * through gateway G.
				 * If the administrator does 'ifconfig I2 down',
				 * the cache entries for D and G will be
				 * flushed. However, G will now be resolved as
				 * an off-link destination using R (the default
				 * router) as gateway. Then D will also be
				 * resolved as an off-link destination using G
				 * as gateway - this behavior is due to
				 * compatibility reasons, see comment in
				 * ire_ihandle_lookup_offlink(). Traffic to D
				 * will go to the router R and probably won't
				 * reach the destination.
				 * The administrator then does 'ifconfig I2 up'.
				 * Since G is on the I2 subnet, this routine
				 * will flush its cache entry. It must also
				 * flush the cache entry for D, otherwise
				 * traffic will stay misrouted until the IRE
				 * times out.
				 */
				if ((cire->ire_gateway_addr & ire->ire_mask) ==
				    (ire->ire_addr & ire->ire_mask)) {
					ire_delete(cire);
					continue;
				}
			}
			IRB_REFRELE(irb);
		}
	} else {
		/*
		 * delete the cache entries based on
		 * handle in the IRE as this IRE is
		 * being deleted/changed.
		 */
		for (i = 0; i < ip_cache_table_size; i++) {
			irb = &ip_cache_table[i];
			if ((cire = irb->irb_ire) == NULL)
				continue;
			IRB_REFHOLD(irb);
			for (cire = irb->irb_ire; cire != NULL;
			    cire = cire->ire_next) {
				if (cire->ire_type != IRE_CACHE)
					continue;
				if ((cire->ire_phandle == 0 ||
				    cire->ire_phandle != ire->ire_phandle) &&
				    (cire->ire_ihandle == 0 ||
				    cire->ire_ihandle != ire->ire_ihandle))
					continue;
				ire_delete(cire);
			}
			IRB_REFRELE(irb);
		}
	}
}

/*
 * Matches the arguments passed with the values in the ire.
 *
 * Note: for match types that match using "ipif" passed in, ipif
 * must be checked for non-NULL before calling this routine.
 */
static boolean_t
ire_match_args(ire_t *ire, ipaddr_t addr, ipaddr_t mask, ipaddr_t gateway,
    int type, ipif_t *ipif, zoneid_t zoneid, uint32_t ihandle, int match_flags)
{
	ill_t *ire_ill = NULL, *dst_ill;
	ill_t *ipif_ill = NULL;
	ill_group_t *ire_ill_group = NULL;
	ill_group_t *ipif_ill_group = NULL;

	ASSERT(ire->ire_ipversion == IPV4_VERSION);
	ASSERT((ire->ire_addr & ~ire->ire_mask) == 0);
	ASSERT((!(match_flags & (MATCH_IRE_ILL|MATCH_IRE_ILL_GROUP))) ||
	    (ipif != NULL && !ipif->ipif_isv6));
	ASSERT(!(match_flags & MATCH_IRE_WQ));

	/*
	 * HIDDEN cache entries have to be looked up specifically with
	 * MATCH_IRE_MARK_HIDDEN. MATCH_IRE_MARK_HIDDEN is usually set
	 * when the interface is FAILED or INACTIVE. In that case,
	 * any IRE_CACHES that exists should be marked with
	 * IRE_MARK_HIDDEN. So, we don't really need to match below
	 * for IRE_MARK_HIDDEN. But we do so for consistency.
	 */
	if (!(match_flags & MATCH_IRE_MARK_HIDDEN) &&
	    (ire->ire_marks & IRE_MARK_HIDDEN))
		return (B_FALSE);

	/*
	 * MATCH_IRE_MARK_PRIVATE_ADDR is set when IP_NEXTHOP option
	 * is used. In that case the routing table is bypassed and the
	 * packets are sent directly to the specified nexthop. The
	 * IRE_CACHE entry representing this route should be marked
	 * with IRE_MARK_PRIVATE_ADDR.
	 */

	if (!(match_flags & MATCH_IRE_MARK_PRIVATE_ADDR) &&
	    (ire->ire_marks & IRE_MARK_PRIVATE_ADDR))
		return (B_FALSE);

	if (zoneid != ALL_ZONES && zoneid != ire->ire_zoneid) {
		/*
		 * If MATCH_IRE_ZONEONLY has been set and the supplied zoneid is
		 * valid and 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_BROADCAST, IRE_CACHE and IRE_LOOPBACK
		 *	entries should never be matched in this situation.
		 *
		 *	IRE entries that have an interface associated with them
		 *	should in general not match unless they are an IRE_LOCAL
		 *	or in the case when MATCH_IRE_DEFAULT has been set in
		 *	the caller.  In the case of the former, checking of the
		 *	other fields supplied should take place.
		 *
		 *	In the case where MATCH_IRE_DEFAULT has been set,
		 *	all of the ipif's associated with the IRE's ill are
		 *	checked to see if there is a matching zoneid.  If any
		 *	one ipif has a matching zoneid, this IRE is a
		 *	potential candidate so checking of the other fields
		 *	takes place.
		 *
		 *	In the case where the IRE_INTERFACE has a usable source
		 *	address (indicated by ill_usesrc_ifindex) in the
		 *	correct zone then it's permitted to return this IRE
		 */
		if (match_flags & MATCH_IRE_ZONEONLY)
			return (B_FALSE);
		if (ire->ire_type & (IRE_BROADCAST | IRE_CACHE | IRE_LOOPBACK))
			return (B_FALSE);
		/*
		 * Note, IRE_INTERFACE can have the stq as NULL. For
		 * example, if the default multicast route is tied to
		 * the loopback address.
		 */
		if ((ire->ire_type & IRE_INTERFACE) &&
		    (ire->ire_stq != NULL)) {
			dst_ill = (ill_t *)ire->ire_stq->q_ptr;
			/*
			 * If there is a usable source address in the
			 * zone, then it's ok to return an
			 * IRE_INTERFACE
			 */
			if (ipif_usesrc_avail(dst_ill, zoneid)) {
				ip3dbg(("ire_match_args: dst_ill %p match %d\n",
				    (void *)dst_ill,
				    (ire->ire_addr == (addr & mask))));
			} else {
				ip3dbg(("ire_match_args: src_ipif NULL"
				    " dst_ill %p\n", (void *)dst_ill));
				return (B_FALSE);
			}
		}
		if (ire->ire_ipif != NULL && ire->ire_type != IRE_LOCAL &&
		    !(ire->ire_type & IRE_INTERFACE)) {
			ipif_t	*tipif;

			if ((match_flags & MATCH_IRE_DEFAULT) == 0) {
				return (B_FALSE);
			}
			mutex_enter(&ire->ire_ipif->ipif_ill->ill_lock);
			for (tipif = ire->ire_ipif->ipif_ill->ill_ipif;
			    tipif != NULL; tipif = tipif->ipif_next) {
				if (IPIF_CAN_LOOKUP(tipif) &&
				    (tipif->ipif_flags & IPIF_UP) &&
				    (tipif->ipif_zoneid == zoneid))
					break;
			}
			mutex_exit(&ire->ire_ipif->ipif_ill->ill_lock);
			if (tipif == NULL) {
				return (B_FALSE);
			}
		}
	}

	/*
	 * For IRE_CACHES, MATCH_IRE_ILL/ILL_GROUP really means that
	 * somebody wants to send out on a particular interface which
	 * is given by ire_stq and hence use ire_stq to derive the ill
	 * value. ire_ipif for IRE_CACHES is just the means of getting
	 * a source address i.e ire_src_addr = ire->ire_ipif->ipif_src_addr.
	 * ire_to_ill does the right thing for this.
	 */
	if (match_flags & (MATCH_IRE_ILL|MATCH_IRE_ILL_GROUP)) {
		ire_ill = ire_to_ill(ire);
		if (ire_ill != NULL)
			ire_ill_group = ire_ill->ill_group;
		ipif_ill = ipif->ipif_ill;
		ipif_ill_group = ipif_ill->ill_group;
	}

	if ((ire->ire_addr == (addr & mask)) &&
	    ((!(match_flags & MATCH_IRE_GW)) ||
		(ire->ire_gateway_addr == gateway)) &&
	    ((!(match_flags & MATCH_IRE_TYPE)) ||
		(ire->ire_type & type)) &&
	    ((!(match_flags & MATCH_IRE_SRC)) ||
		(ire->ire_src_addr == ipif->ipif_src_addr)) &&
	    ((!(match_flags & MATCH_IRE_IPIF)) ||
		(ire->ire_ipif == ipif)) &&
	    ((!(match_flags & MATCH_IRE_MARK_HIDDEN)) ||
		(ire->ire_type != IRE_CACHE ||
		ire->ire_marks & IRE_MARK_HIDDEN)) &&
	    ((!(match_flags & MATCH_IRE_MARK_PRIVATE_ADDR)) ||
		(ire->ire_type != IRE_CACHE ||
		ire->ire_marks & IRE_MARK_PRIVATE_ADDR)) &&
	    ((!(match_flags & MATCH_IRE_ILL)) ||
		(ire_ill == ipif_ill)) &&
	    ((!(match_flags & MATCH_IRE_IHANDLE)) ||
		(ire->ire_ihandle == ihandle)) &&
	    ((!(match_flags & MATCH_IRE_ILL_GROUP)) ||
		(ire_ill == ipif_ill) ||
		(ire_ill_group != NULL &&
		ire_ill_group == ipif_ill_group))) {
		/* We found the matched IRE */
		return (B_TRUE);
	}
	return (B_FALSE);
}


/*
 * Lookup for a route in all the tables
 */
ire_t *
ire_route_lookup(ipaddr_t addr, ipaddr_t mask, ipaddr_t gateway,
    int type, ipif_t *ipif, ire_t **pire, zoneid_t zoneid, int flags)
{
	ire_t *ire = NULL;

	/*
	 * ire_match_args() will dereference ipif MATCH_IRE_SRC or
	 * MATCH_IRE_ILL is set.
	 */
	if ((flags & (MATCH_IRE_SRC | MATCH_IRE_ILL | MATCH_IRE_ILL_GROUP)) &&
	    (ipif == NULL))
		return (NULL);

	/*
	 * might be asking for a cache lookup,
	 * This is not best way to lookup cache,
	 * user should call ire_cache_lookup directly.
	 *
	 * If MATCH_IRE_TYPE was set, first lookup in the cache table and then
	 * in the forwarding table, if the applicable type flags were set.
	 */
	if ((flags & MATCH_IRE_TYPE) == 0 || (type & IRE_CACHETABLE) != 0) {
		ire = ire_ctable_lookup(addr, gateway, type, ipif, zoneid,
		    flags);
		if (ire != NULL)
			return (ire);
	}
	if ((flags & MATCH_IRE_TYPE) == 0 || (type & IRE_FORWARDTABLE) != 0) {
		ire = ire_ftable_lookup(addr, mask, gateway, type, ipif, pire,
		    zoneid, 0, flags);
	}
	return (ire);
}

/*
 * Lookup a route in forwarding table.
 * specific lookup is indicated by passing the
 * required parameters and indicating the
 * match required in flag field.
 *
 * Looking for default route can be done in three ways
 * 1) pass mask as 0 and set MATCH_IRE_MASK in flags field
 *    along with other matches.
 * 2) pass type as IRE_DEFAULT and set MATCH_IRE_TYPE in flags
 *    field along with other matches.
 * 3) if the destination and mask are passed as zeros.
 *
 * A request to return a default route if no route
 * is found, can be specified by setting MATCH_IRE_DEFAULT
 * in flags.
 *
 * It does not support recursion more than one level. It
 * will do recursive lookup only when the lookup maps to
 * a prefix or default route and MATCH_IRE_RECURSIVE flag is passed.
 *
 * If the routing table is setup to allow more than one level
 * of recursion, the cleaning up cache table will not work resulting
 * in invalid routing.
 *
 * Supports IP_BOUND_IF by following the ipif/ill when recursing.
 *
 * NOTE : When this function returns NULL, pire has already been released.
 *	  pire is valid only when this function successfully returns an
 *	  ire.
 */
ire_t *
ire_ftable_lookup(ipaddr_t addr, ipaddr_t mask, ipaddr_t gateway,
    int type, ipif_t *ipif, ire_t **pire, zoneid_t zoneid, uint32_t ihandle,
    int flags)
{
	irb_t *irb_ptr;
	ire_t *ire = NULL;
	int i;
	ipaddr_t gw_addr;

	ASSERT(ipif == NULL || !ipif->ipif_isv6);
	ASSERT(!(flags & MATCH_IRE_WQ));

	/*
	 * When we return NULL from this function, we should make
	 * sure that *pire is NULL so that the callers will not
	 * wrongly REFRELE the pire.
	 */
	if (pire != NULL)
		*pire = NULL;
	/*
	 * ire_match_args() will dereference ipif MATCH_IRE_SRC or
	 * MATCH_IRE_ILL is set.
	 */
	if ((flags & (MATCH_IRE_SRC | MATCH_IRE_ILL | MATCH_IRE_ILL_GROUP)) &&
	    (ipif == NULL))
		return (NULL);

	/*
	 * If the mask is known, the lookup
	 * is simple, if the mask is not known
	 * we need to search.
	 */
	if (flags & MATCH_IRE_MASK) {
		uint_t masklen;

		masklen = ip_mask_to_plen(mask);
		if (ip_forwarding_table[masklen] == NULL)
			return (NULL);
		irb_ptr = &(ip_forwarding_table[masklen][
		    IRE_ADDR_HASH(addr & mask, ip_ftable_hash_size)]);
		rw_enter(&irb_ptr->irb_lock, RW_READER);
		for (ire = irb_ptr->irb_ire; ire != NULL;
		    ire = ire->ire_next) {
			if (ire->ire_marks & IRE_MARK_CONDEMNED)
				continue;
			if (ire_match_args(ire, addr, mask, gateway, type, ipif,
			    zoneid, ihandle, flags))
				goto found_ire;
		}
		rw_exit(&irb_ptr->irb_lock);
	} else {
		/*
		 * In this case we don't know the mask, we need to
		 * search the table assuming different mask sizes.
		 * we start with 32 bit mask, we don't allow default here.
		 */
		for (i = (IP_MASK_TABLE_SIZE - 1); i > 0; i--) {
			ipaddr_t tmpmask;

			if ((ip_forwarding_table[i]) == NULL)
				continue;
			tmpmask = ip_plen_to_mask(i);
			irb_ptr = &ip_forwarding_table[i][
			    IRE_ADDR_HASH(addr & tmpmask,
			    ip_ftable_hash_size)];
			rw_enter(&irb_ptr->irb_lock, RW_READER);
			for (ire = irb_ptr->irb_ire; ire != NULL;
			    ire = ire->ire_next) {
				if (ire->ire_marks & IRE_MARK_CONDEMNED)
					continue;
				if (ire_match_args(ire, addr, ire->ire_mask,
				    gateway, type, ipif, zoneid, ihandle,
				    flags))
					goto found_ire;
			}
			rw_exit(&irb_ptr->irb_lock);
		}
	}
	/*
	 * We come here if no route has yet been found.
	 *
	 * Handle the case where default route is
	 * requested by specifying type as one of the possible
	 * types for that can have a zero mask (IRE_DEFAULT and IRE_INTERFACE).
	 *
	 * If MATCH_IRE_MASK is specified, then the appropriate default route
	 * would have been found above if it exists so it isn't looked up here.
	 * If MATCH_IRE_DEFAULT was also specified, then a default route will be
	 * searched for later.
	 */
	if ((flags & (MATCH_IRE_TYPE | MATCH_IRE_MASK)) == MATCH_IRE_TYPE &&
	    (type & (IRE_DEFAULT | IRE_INTERFACE))) {
		if ((ip_forwarding_table[0])) {
			/* addr & mask is zero for defaults */
			irb_ptr = &ip_forwarding_table[0][
			    IRE_ADDR_HASH(0, ip_ftable_hash_size)];
			rw_enter(&irb_ptr->irb_lock, RW_READER);
			for (ire = irb_ptr->irb_ire; ire != NULL;
			    ire = ire->ire_next) {
				if (ire->ire_marks & IRE_MARK_CONDEMNED)
					continue;
				if (ire_match_args(ire, addr, (ipaddr_t)0,
				    gateway, type, ipif, zoneid, ihandle,
				    flags))
					goto found_ire;
			}
			rw_exit(&irb_ptr->irb_lock);
		}
	}
	/*
	 * we come here only if no route is found.
	 * see if the default route can be used which is allowed
	 * only if the default matching criteria is specified.
	 * The ip_ire_default_count tracks the number of IRE_DEFAULT
	 * entries. However, the ip_forwarding_table[0] also contains
	 * interface routes thus the count can be zero.
	 */
	if ((flags & (MATCH_IRE_DEFAULT | MATCH_IRE_MASK)) ==
	    MATCH_IRE_DEFAULT) {
		ire_t	*ire_origin;
		uint_t  g_index;
		uint_t	index;

		if (ip_forwarding_table[0] == NULL)
			return (NULL);
		irb_ptr = &(ip_forwarding_table[0])[0];

		/*
		 * Keep a tab on the bucket while looking the IRE_DEFAULT
		 * entries. We need to keep track of a particular IRE
		 * (ire_origin) so this ensures that it will not be unlinked
		 * from the hash list during the recursive lookup below.
		 */
		IRB_REFHOLD(irb_ptr);
		ire = irb_ptr->irb_ire;
		if (ire == NULL) {
			IRB_REFRELE(irb_ptr);
			return (NULL);
		}

		/*
		 * Get the index first, since it can be changed by other
		 * threads. Then get to the right default route skipping
		 * default interface routes if any. As we hold a reference on
		 * the IRE bucket, ip_ire_default_count can only increase so we
		 * can't reach the end of the hash list unexpectedly.
		 */
		if (ip_ire_default_count != 0) {
			g_index = ip_ire_default_index++;
			index = g_index % ip_ire_default_count;
			while (index != 0) {
				if (!(ire->ire_type & IRE_INTERFACE))
					index--;
				ire = ire->ire_next;
			}
			ASSERT(ire != NULL);
		} else {
			/*
			 * No default routes, so we only have default interface
			 * routes: don't enter the first loop.
			 */
			ire = NULL;
		}

		/*
		 * Round-robin the default routers list looking for a route that
		 * matches the passed in parameters. If we can't find a default
		 * route (IRE_DEFAULT), look for interface default routes.
		 * We start with the ire we found above and we walk the hash
		 * list until we're back where we started, see
		 * ire_get_next_default_ire(). It doesn't matter if default
		 * routes are added or deleted by other threads - we know this
		 * ire will stay in the list because we hold a reference on the
		 * ire bucket.
		 * NB: if we only have interface default routes, ire is NULL so
		 * we don't even enter this loop (see above).
		 */
		ire_origin = ire;
		for (; ire != NULL;
		    ire = ire_get_next_default_ire(ire, ire_origin)) {

			if (ire_match_args(ire, addr, (ipaddr_t)0,
			    gateway, type, ipif, zoneid, ihandle, flags)) {
				int match_flags = 0;
				ire_t *rire;

				/*
				 * The potentially expensive call to
				 * ire_route_lookup() is avoided when we have
				 * only one default route.
				 */
				if (ip_ire_default_count == 1 ||
				    zoneid == ALL_ZONES) {
					IRE_REFHOLD(ire);
					IRB_REFRELE(irb_ptr);
					goto found_ire_held;
				}
				/*
				 * When we're in a local zone, we're only
				 * interested in default routers that are
				 * reachable through ipifs within our zone.
				 */
				if (ire->ire_ipif != NULL) {
					match_flags |= MATCH_IRE_ILL_GROUP;
				}
				rire = ire_route_lookup(ire->ire_gateway_addr,
				    0, 0, 0, ire->ire_ipif, NULL, zoneid,
				    match_flags);
				if (rire != NULL) {
					ire_refrele(rire);
					IRE_REFHOLD(ire);
					IRB_REFRELE(irb_ptr);
					goto found_ire_held;
				}
			}
		}
		/*
		 * Either there are no default routes or we could not
		 * find a default route. Look for a interface default
		 * route matching the args passed in. No round robin
		 * here. Just pick the right one.
		 */
		for (ire = irb_ptr->irb_ire; ire != NULL;
		    ire = ire->ire_next) {

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

			if (ire->ire_marks & IRE_MARK_CONDEMNED)
				continue;

			if (ire_match_args(ire, addr, (ipaddr_t)0,
			    gateway, type, ipif, zoneid, ihandle, flags)) {
				IRE_REFHOLD(ire);
				IRB_REFRELE(irb_ptr);
				goto found_ire_held;
			}
		}
		IRB_REFRELE(irb_ptr);
	}
	ASSERT(ire == NULL);
	return (NULL);
found_ire:
	ASSERT((ire->ire_marks & IRE_MARK_CONDEMNED) == 0);
	IRE_REFHOLD(ire);
	rw_exit(&irb_ptr->irb_lock);

found_ire_held:
	ASSERT(ire->ire_type != IRE_MIPRTUN && ire->ire_in_ill == NULL);
	if ((flags & MATCH_IRE_RJ_BHOLE) &&
	    (ire->ire_flags & (RTF_BLACKHOLE | RTF_REJECT))) {
		return (ire);
	}
	/*
	 * At this point, IRE that was found must be an IRE_FORWARDTABLE
	 * type.  If this is a recursive lookup and an IRE_INTERFACE type was
	 * found, return that.  If it was some other IRE_FORWARDTABLE type of
	 * IRE (one of the prefix types), then it is necessary to fill in the
	 * parent IRE pointed to by pire, and then lookup the gateway address of
	 * the parent.  For backwards compatiblity, if this lookup returns an
	 * IRE other than a IRE_CACHETABLE or IRE_INTERFACE, then one more level
	 * of lookup is done.
	 */
	if (flags & MATCH_IRE_RECURSIVE) {
		ipif_t	*gw_ipif;
		int match_flags = MATCH_IRE_DSTONLY;
		ire_t *save_ire;

		if (ire->ire_type & IRE_INTERFACE)
			return (ire);
		if (pire != NULL)
			*pire = ire;
		/*
		 * If we can't find an IRE_INTERFACE or the caller has not
		 * asked for pire, we need to REFRELE the save_ire.
		 */
		save_ire = ire;

		/*
		 * Currently MATCH_IRE_ILL is never used with
		 * (MATCH_IRE_RECURSIVE | MATCH_IRE_DEFAULT) while
		 * sending out packets as MATCH_IRE_ILL is used only
		 * for communicating with on-link hosts. We can't assert
		 * that here as RTM_GET calls this function with
		 * MATCH_IRE_ILL | MATCH_IRE_DEFAULT | MATCH_IRE_RECURSIVE.
		 * We have already used the MATCH_IRE_ILL in determining
		 * the right prefix route at this point. To match the
		 * behavior of how we locate routes while sending out
		 * packets, we don't want to use MATCH_IRE_ILL below
		 * while locating the interface route.
		 */
		if (ire->ire_ipif != NULL)
			match_flags |= MATCH_IRE_ILL_GROUP;

		ire = ire_route_lookup(ire->ire_gateway_addr, 0, 0, 0,
		    ire->ire_ipif, NULL, zoneid, match_flags);
		if (ire == NULL) {
			/*
			 * Do not release the parent ire if MATCH_IRE_PARENT
			 * is set. Also return it via ire.
			 */
			if (flags & MATCH_IRE_PARENT) {
				if (pire != NULL) {
					/*
					 * Need an extra REFHOLD, if the parent
					 * ire is returned via both ire and
					 * pire.
					 */
					IRE_REFHOLD(save_ire);
				}
				ire = save_ire;
			} else {
				ire_refrele(save_ire);
				if (pire != NULL)
					*pire = NULL;
			}
			return (ire);
		}
		if (ire->ire_type & (IRE_CACHETABLE | IRE_INTERFACE)) {
			/*
			 * If the caller did not ask for pire, release
			 * it now.
			 */
			if (pire == NULL) {
				ire_refrele(save_ire);
			}
			return (ire);
		}
		match_flags |= MATCH_IRE_TYPE;
		gw_addr = ire->ire_gateway_addr;
		gw_ipif = ire->ire_ipif;
		ire_refrele(ire);
		ire = ire_route_lookup(gw_addr, 0, 0,
		    (IRE_CACHETABLE | IRE_INTERFACE), gw_ipif, NULL, zoneid,
		    match_flags);
		if (ire == NULL) {
			/*
			 * Do not release the parent ire if MATCH_IRE_PARENT
			 * is set. Also return it via ire.
			 */
			if (flags & MATCH_IRE_PARENT) {
				if (pire != NULL) {
					/*
					 * Need an extra REFHOLD, if the
					 * parent ire is returned via both
					 * ire and pire.
					 */
					IRE_REFHOLD(save_ire);
				}
				ire = save_ire;
			} else {
				ire_refrele(save_ire);
				if (pire != NULL)
					*pire = NULL;
			}
			return (ire);
		} else if (pire == NULL) {
			/*
			 * If the caller did not ask for pire, release
			 * it now.
			 */
			ire_refrele(save_ire);
		}
		return (ire);
	}
	ASSERT(pire == NULL || *pire == NULL);
	return (ire);
}

/*
 * Looks up cache table for a route.
 * specific lookup can be indicated by
 * passing the MATCH_* flags and the
 * necessary parameters.
 */
ire_t *
ire_ctable_lookup(ipaddr_t addr, ipaddr_t gateway, int type, ipif_t *ipif,
    zoneid_t zoneid, int flags)
{
	irb_t *irb_ptr;
	ire_t *ire;

	/*
	 * ire_match_args() will dereference ipif MATCH_IRE_SRC or
	 * MATCH_IRE_ILL is set.
	 */
	if ((flags & (MATCH_IRE_SRC | MATCH_IRE_ILL | MATCH_IRE_ILL_GROUP)) &&
	    (ipif == NULL))
		return (NULL);

	irb_ptr = &ip_cache_table[IRE_ADDR_HASH(addr, ip_cache_table_size)];
	rw_enter(&irb_ptr->irb_lock, RW_READER);
	for (ire = irb_ptr->irb_ire; ire != NULL; ire = ire->ire_next) {
		if (ire->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		ASSERT(ire->ire_mask == IP_HOST_MASK);
		ASSERT(ire->ire_type != IRE_MIPRTUN && ire->ire_in_ill == NULL);
		if (ire_match_args(ire, addr, ire->ire_mask, gateway, type,
		    ipif, zoneid, 0, flags)) {
			IRE_REFHOLD(ire);
			rw_exit(&irb_ptr->irb_lock);
			return (ire);
		}
	}
	rw_exit(&irb_ptr->irb_lock);
	return (NULL);
}

/*
 * Lookup cache. Don't return IRE_MARK_HIDDEN entries. Callers
 * should use ire_ctable_lookup with MATCH_IRE_MARK_HIDDEN to get
 * to the hidden ones.
 */
ire_t *
ire_cache_lookup(ipaddr_t addr, zoneid_t zoneid)
{
	irb_t *irb_ptr;
	ire_t *ire;

	irb_ptr = &ip_cache_table[IRE_ADDR_HASH(addr, ip_cache_table_size)];
	rw_enter(&irb_ptr->irb_lock, RW_READER);
	for (ire = irb_ptr->irb_ire; ire != NULL; ire = ire->ire_next) {
		if (ire->ire_marks & (IRE_MARK_CONDEMNED |
		    IRE_MARK_HIDDEN | IRE_MARK_PRIVATE_ADDR)) {
			continue;
		}
		if (ire->ire_addr == addr) {
			if (zoneid == ALL_ZONES || ire->ire_zoneid == zoneid ||
			    ire->ire_type == IRE_LOCAL) {
				IRE_REFHOLD(ire);
				rw_exit(&irb_ptr->irb_lock);
				return (ire);
			}
		}
	}
	rw_exit(&irb_ptr->irb_lock);
	return (NULL);
}

/*
 * Locate the interface ire that is tied to the cache ire 'cire' via
 * cire->ire_ihandle.
 *
 * We are trying to create the cache ire for an offlink destn based
 * on the cache ire of the gateway in 'cire'. 'pire' is the prefix ire
 * as found by ip_newroute(). We are called from ip_newroute() in
 * the IRE_CACHE case.
 */
ire_t *
ire_ihandle_lookup_offlink(ire_t *cire, ire_t *pire)
{
	ire_t	*ire;
	int	match_flags;
	ipaddr_t gw_addr;
	ipif_t	*gw_ipif;

	ASSERT(cire != NULL && pire != NULL);

	/*
	 * We don't need to specify the zoneid to ire_ftable_lookup() below
	 * because the ihandle refers to an ipif which can be in only one zone.
	 */
	match_flags =  MATCH_IRE_TYPE | MATCH_IRE_IHANDLE | MATCH_IRE_MASK;
	/*
	 * ip_newroute calls ire_ftable_lookup with MATCH_IRE_ILL only
	 * for on-link hosts. We should never be here for onlink.
	 * Thus, use MATCH_IRE_ILL_GROUP.
	 */
	if (pire->ire_ipif != NULL)
		match_flags |= MATCH_IRE_ILL_GROUP;
	/*
	 * We know that the mask of the interface ire equals cire->ire_cmask.
	 * (When ip_newroute() created 'cire' for the gateway it set its
	 * cmask from the interface ire's mask)
	 */
	ire = ire_ftable_lookup(cire->ire_addr, cire->ire_cmask, 0,
	    IRE_INTERFACE, pire->ire_ipif, NULL, ALL_ZONES, cire->ire_ihandle,
	    match_flags);
	if (ire != NULL)
		return (ire);
	/*
	 * If we didn't find an interface ire above, we can't declare failure.
	 * For backwards compatibility, we need to support prefix routes
	 * pointing to next hop gateways that are not on-link.
	 *
	 * Assume we are trying to ping some offlink destn, and we have the
	 * routing table below.
	 *
	 * Eg.	default	- gw1		<--- pire	(line 1)
	 *	gw1	- gw2				(line 2)
	 *	gw2	- hme0				(line 3)
	 *
	 * If we already have a cache ire for gw1 in 'cire', the
	 * ire_ftable_lookup above would have failed, since there is no
	 * interface ire to reach gw1. We will fallthru below.
	 *
	 * Here we duplicate the steps that ire_ftable_lookup() did in
	 * getting 'cire' from 'pire', in the MATCH_IRE_RECURSIVE case.
	 * The differences are the following
	 * i.   We want the interface ire only, so we call ire_ftable_lookup()
	 *	instead of ire_route_lookup()
	 * ii.  We look for only prefix routes in the 1st call below.
	 * ii.  We want to match on the ihandle in the 2nd call below.
	 */
	match_flags =  MATCH_IRE_TYPE;
	if (pire->ire_ipif != NULL)
		match_flags |= MATCH_IRE_ILL_GROUP;
	ire = ire_ftable_lookup(pire->ire_gateway_addr, 0, 0, IRE_OFFSUBNET,
	    pire->ire_ipif, NULL, ALL_ZONES, 0, match_flags);
	if (ire == NULL)
		return (NULL);
	/*
	 * At this point 'ire' corresponds to the entry shown in line 2.
	 * gw_addr is 'gw2' in the example above.
	 */
	gw_addr = ire->ire_gateway_addr;
	gw_ipif = ire->ire_ipif;
	ire_refrele(ire);

	match_flags |= MATCH_IRE_IHANDLE;
	ire = ire_ftable_lookup(gw_addr, 0, 0, IRE_INTERFACE,
	    gw_ipif, NULL, ALL_ZONES, cire->ire_ihandle, match_flags);
	return (ire);
}

/*
 * Locate the interface ire that is tied to the cache ire 'cire' via
 * cire->ire_ihandle.
 *
 * We are trying to create the cache ire for an onlink destn. or
 * gateway in 'cire'. We are called from ire_add_v4() in the IRE_IF_RESOLVER
 * case, after the ire has come back from ARP.
 */
ire_t *
ire_ihandle_lookup_onlink(ire_t *cire)
{
	ire_t	*ire;
	int	match_flags;
	int	i;
	int	j;
	irb_t	*irb_ptr;

	ASSERT(cire != NULL);

	/*
	 * We don't need to specify the zoneid to ire_ftable_lookup() below
	 * because the ihandle refers to an ipif which can be in only one zone.
	 */
	match_flags =  MATCH_IRE_TYPE | MATCH_IRE_IHANDLE | MATCH_IRE_MASK;
	/*
	 * We know that the mask of the interface ire equals cire->ire_cmask.
	 * (When ip_newroute() created 'cire' for an on-link destn. it set its
	 * cmask from the interface ire's mask)
	 */
	ire = ire_ftable_lookup(cire->ire_addr, cire->ire_cmask, 0,
	    IRE_INTERFACE, NULL, NULL, ALL_ZONES, cire->ire_ihandle,
	    match_flags);
	if (ire != NULL)
		return (ire);
	/*
	 * If we didn't find an interface ire above, we can't declare failure.
	 * For backwards compatibility, we need to support prefix routes
	 * pointing to next hop gateways that are not on-link.
	 *
	 * In the resolver/noresolver case, ip_newroute() thinks it is creating
	 * the cache ire for an onlink destination in 'cire'. But 'cire' is
	 * not actually onlink, because ire_ftable_lookup() cheated it, by
	 * doing ire_route_lookup() twice and returning an interface ire.
	 *
	 * Eg. default	-	gw1			(line 1)
	 *	gw1	-	gw2			(line 2)
	 *	gw2	-	hme0			(line 3)
	 *
	 * In the above example, ip_newroute() tried to create the cache ire
	 * 'cire' for gw1, based on the interface route in line 3. The
	 * ire_ftable_lookup() above fails, because there is no interface route
	 * to reach gw1. (it is gw2). We fall thru below.
	 *
	 * Do a brute force search based on the ihandle in a subset of the
	 * forwarding tables, corresponding to cire->ire_cmask. Otherwise
	 * things become very complex, since we don't have 'pire' in this
	 * case. (Also note that this method is not possible in the offlink
	 * case because we don't know the mask)
	 */
	i = ip_mask_to_plen(cire->ire_cmask);
	if ((ip_forwarding_table[i]) == NULL)
		return (NULL);
	for (j = 0; j < ip_ftable_hash_size; j++) {
		irb_ptr = &ip_forwarding_table[i][j];
		rw_enter(&irb_ptr->irb_lock, RW_READER);
		for (ire = irb_ptr->irb_ire; ire != NULL;
		    ire = ire->ire_next) {
			if (ire->ire_marks & IRE_MARK_CONDEMNED)
				continue;
			if ((ire->ire_type & IRE_INTERFACE) &&
			    (ire->ire_ihandle == cire->ire_ihandle)) {
				IRE_REFHOLD(ire);
				rw_exit(&irb_ptr->irb_lock);
				return (ire);
			}
		}
		rw_exit(&irb_ptr->irb_lock);
	}
	return (NULL);
}

/*
 * ire_mrtun_lookup() is called by ip_rput() when packet is to be
 * tunneled through reverse tunnel. This is only supported for
 * IPv4 packets
 */

ire_t *
ire_mrtun_lookup(ipaddr_t srcaddr, ill_t *ill)
{
	irb_t *irb_ptr;
	ire_t *ire;

	ASSERT(ill != NULL);
	ASSERT(!(ill->ill_isv6));

	if (ip_mrtun_table == NULL)
		return (NULL);
	irb_ptr = &ip_mrtun_table[IRE_ADDR_HASH(srcaddr, IP_MRTUN_TABLE_SIZE)];
	rw_enter(&irb_ptr->irb_lock, RW_READER);
	for (ire = irb_ptr->irb_ire; ire != NULL; ire = ire->ire_next) {
		if (ire->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		if ((ire->ire_in_src_addr == srcaddr) &&
		    ire->ire_in_ill == ill) {
			IRE_REFHOLD(ire);
			rw_exit(&irb_ptr->irb_lock);
			return (ire);
		}
	}
	rw_exit(&irb_ptr->irb_lock);
	return (NULL);
}

/*
 * Return the IRE_LOOPBACK, IRE_IF_RESOLVER or IRE_IF_NORESOLVER
 * ire associated with the specified ipif.
 *
 * This might occasionally be called when IPIF_UP is not set since
 * the IP_MULTICAST_IF as well as creating interface routes
 * allows specifying a down ipif (ipif_lookup* match ipifs that are down).
 *
 * Note that if IPIF_NOLOCAL, IPIF_NOXMIT, or IPIF_DEPRECATED is set on
 * the ipif, this routine might return NULL.
 */
ire_t *
ipif_to_ire(ipif_t *ipif)
{
	ire_t	*ire;

	ASSERT(!ipif->ipif_isv6);
	if (ipif->ipif_ire_type == IRE_LOOPBACK) {
		ire = ire_ctable_lookup(ipif->ipif_lcl_addr, 0, IRE_LOOPBACK,
		    ipif, ALL_ZONES, (MATCH_IRE_TYPE | MATCH_IRE_IPIF));
	} else if (ipif->ipif_flags & IPIF_POINTOPOINT) {
		/* In this case we need to lookup destination address. */
		ire = ire_ftable_lookup(ipif->ipif_pp_dst_addr, IP_HOST_MASK, 0,
		    IRE_INTERFACE, ipif, NULL, ALL_ZONES, 0,
		    (MATCH_IRE_TYPE | MATCH_IRE_IPIF | MATCH_IRE_MASK));
	} else {
		ire = ire_ftable_lookup(ipif->ipif_subnet,
		    ipif->ipif_net_mask, 0, IRE_INTERFACE, ipif, NULL,
		    ALL_ZONES, 0, (MATCH_IRE_TYPE | MATCH_IRE_IPIF |
		    MATCH_IRE_MASK));
	}
	return (ire);
}

/*
 * ire_walk function.
 * Count the number of IRE_CACHE entries in different categories.
 */
void
ire_cache_count(ire_t *ire, char *arg)
{
	ire_cache_count_t *icc = (ire_cache_count_t *)arg;

	if (ire->ire_type != IRE_CACHE)
		return;

	icc->icc_total++;

	if (ire->ire_ipversion == IPV6_VERSION) {
		mutex_enter(&ire->ire_lock);
		if (IN6_IS_ADDR_UNSPECIFIED(&ire->ire_gateway_addr_v6)) {
			mutex_exit(&ire->ire_lock);
			icc->icc_onlink++;
			return;
		}
		mutex_exit(&ire->ire_lock);
	} else {
		if (ire->ire_gateway_addr == 0) {
			icc->icc_onlink++;
			return;
		}
	}

	ASSERT(ire->ire_ipif != NULL);
	if (ire->ire_max_frag < ire->ire_ipif->ipif_mtu)
		icc->icc_pmtu++;
	else if (ire->ire_tire_mark != ire->ire_ob_pkt_count +
	    ire->ire_ib_pkt_count)
		icc->icc_offlink++;
	else
		icc->icc_unused++;
}

/*
 * ire_walk function called by ip_trash_ire_reclaim().
 * Free a fraction of the IRE_CACHE cache entries. The fractions are
 * different for different categories of IRE_CACHE entries.
 * A fraction of zero means to not free any in that category.
 * Use the hash bucket id plus lbolt as a random number. Thus if the fraction
 * is N then every Nth hash bucket chain will be freed.
 */
void
ire_cache_reclaim(ire_t *ire, char *arg)
{
	ire_cache_reclaim_t *icr = (ire_cache_reclaim_t *)arg;
	uint_t rand;

	if (ire->ire_type != IRE_CACHE)
		return;

	if (ire->ire_ipversion == IPV6_VERSION) {
		rand = (uint_t)lbolt +
		    IRE_ADDR_HASH_V6(ire->ire_addr_v6, ip6_cache_table_size);
		mutex_enter(&ire->ire_lock);
		if (IN6_IS_ADDR_UNSPECIFIED(&ire->ire_gateway_addr_v6)) {
			mutex_exit(&ire->ire_lock);
			if (icr->icr_onlink != 0 &&
			    (rand/icr->icr_onlink)*icr->icr_onlink == rand) {
				ire_delete(ire);
				return;
			}
			goto done;
		}
		mutex_exit(&ire->ire_lock);
	} else {
		rand = (uint_t)lbolt +
		    IRE_ADDR_HASH(ire->ire_addr, ip_cache_table_size);
		if (ire->ire_gateway_addr == 0) {
			if (icr->icr_onlink != 0 &&
			    (rand/icr->icr_onlink)*icr->icr_onlink == rand) {
				ire_delete(ire);
				return;
			}
			goto done;
		}
	}
	/* Not onlink IRE */
	ASSERT(ire->ire_ipif != NULL);
	if (ire->ire_max_frag < ire->ire_ipif->ipif_mtu) {
		/* Use ptmu fraction */
		if (icr->icr_pmtu != 0 &&
		    (rand/icr->icr_pmtu)*icr->icr_pmtu == rand) {
			ire_delete(ire);
			return;
		}
	} else if (ire->ire_tire_mark != ire->ire_ob_pkt_count +
	    ire->ire_ib_pkt_count) {
		/* Use offlink fraction */
		if (icr->icr_offlink != 0 &&
		    (rand/icr->icr_offlink)*icr->icr_offlink == rand) {
			ire_delete(ire);
			return;
		}
	} else {
		/* Use unused fraction */
		if (icr->icr_unused != 0 &&
		    (rand/icr->icr_unused)*icr->icr_unused == rand) {
			ire_delete(ire);
			return;
		}
	}
done:
	/*
	 * Update tire_mark so that those that haven't been used since this
	 * reclaim will be considered unused next time we reclaim.
	 */
	ire->ire_tire_mark = ire->ire_ob_pkt_count + ire->ire_ib_pkt_count;
}

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

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

void
ip_ire_init()
{
	int i;

	mutex_init(&ire_ft_init_lock, NULL, MUTEX_DEFAULT, 0);
	mutex_init(&ire_handle_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&ire_mrtun_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&ire_srcif_table_lock, NULL, MUTEX_DEFAULT, NULL);

	/* Calculate the IPv4 cache table size. */
	ip_cache_table_size = MAX(ip_cache_table_size,
	    ((kmem_avail() >> ip_ire_mem_ratio) / sizeof (ire_t) /
	    ip_ire_max_bucket_cnt));
	if (ip_cache_table_size > ip_max_cache_table_size)
		ip_cache_table_size = ip_max_cache_table_size;
	/*
	 * Make sure that the table size is always a power of 2.  The
	 * hash macro IRE_ADDR_HASH() depends on that.
	 */
	power2_roundup(&ip_cache_table_size);

	ip_cache_table = (irb_t *)kmem_zalloc(ip_cache_table_size *
	    sizeof (irb_t), KM_SLEEP);

	for (i = 0; i < ip_cache_table_size; i++) {
		rw_init(&ip_cache_table[i].irb_lock, NULL,
		    RW_DEFAULT, NULL);
	}

	/* Calculate the IPv6 cache table size. */
	ip6_cache_table_size = MAX(ip6_cache_table_size,
	    ((kmem_avail() >> ip_ire_mem_ratio) / sizeof (ire_t) /
	    ip6_ire_max_bucket_cnt));
	if (ip6_cache_table_size > ip6_max_cache_table_size)
		ip6_cache_table_size = ip6_max_cache_table_size;
	/*
	 * Make sure that the table size is always a power of 2.  The
	 * hash macro IRE_ADDR_HASH_V6() depends on that.
	 */
	power2_roundup(&ip6_cache_table_size);

	ip_cache_table_v6 = (irb_t *)kmem_zalloc(ip6_cache_table_size *
	    sizeof (irb_t), KM_SLEEP);

	for (i = 0; i < ip6_cache_table_size; i++) {
		rw_init(&ip_cache_table_v6[i].irb_lock, NULL,
		    RW_DEFAULT, NULL);
	}
	/*
	 * Create ire caches, ire_reclaim()
	 * will give IRE_CACHE 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, ip_ire_constructor,
		ip_ire_destructor, ip_trash_ire_reclaim, NULL, NULL, 0);

	/*
	 * Initialize ip_mrtun_table to NULL now, it will be
	 * populated by ip_rt_add if reverse tunnel is created
	 */
	ip_mrtun_table = NULL;

	/*
	 * Make sure that the forwarding table size is a power of 2.
	 * The IRE*_ADDR_HASH() macroes depend on that.
	 */
	power2_roundup(&ip_ftable_hash_size);
	power2_roundup(&ip6_ftable_hash_size);
}

void
ip_ire_fini()
{
	int i;

	mutex_destroy(&ire_ft_init_lock);
	mutex_destroy(&ire_handle_lock);

	for (i = 0; i < ip_cache_table_size; i++) {
		rw_destroy(&ip_cache_table[i].irb_lock);
	}
	kmem_free(ip_cache_table, ip_cache_table_size * sizeof (irb_t));

	for (i = 0; i < ip6_cache_table_size; i++) {
		rw_destroy(&ip_cache_table_v6[i].irb_lock);
	}
	kmem_free(ip_cache_table_v6, ip6_cache_table_size * sizeof (irb_t));

	if (ip_mrtun_table != NULL) {
		for (i = 0; i < IP_MRTUN_TABLE_SIZE; i++) {
			rw_destroy(&ip_mrtun_table[i].irb_lock);
		}
		kmem_free(ip_mrtun_table, IP_MRTUN_TABLE_SIZE * sizeof (irb_t));
	}
	kmem_cache_destroy(ire_cache);
}

int
ire_add_mrtun(ire_t **ire_p, queue_t *q, mblk_t *mp, ipsq_func_t func)
{
	ire_t   *ire1;
	irb_t	*irb_ptr;
	ire_t	**irep;
	ire_t	*ire;
	int	i;
	uint_t	max_frag;
	ill_t	*stq_ill;
	int error;

	ire = *ire_p;
	ASSERT(ire->ire_ipversion == IPV4_VERSION);
	/* Is ip_mrtun_table empty ? */

	if (ip_mrtun_table == NULL) {
		/* create the mrtun table */
		mutex_enter(&ire_mrtun_lock);
		if (ip_mrtun_table == NULL) {
			ip_mrtun_table =
			    (irb_t *)kmem_zalloc(IP_MRTUN_TABLE_SIZE *
			    sizeof (irb_t), KM_NOSLEEP);

			if (ip_mrtun_table == NULL) {
				ip2dbg(("ire_add_mrtun: allocation failure\n"));
				mutex_exit(&ire_mrtun_lock);
				ire_refrele(ire);
				*ire_p = NULL;
				return (ENOMEM);
			}

			for (i = 0; i < IP_MRTUN_TABLE_SIZE; i++) {
			    rw_init(&ip_mrtun_table[i].irb_lock, NULL,
				    RW_DEFAULT, NULL);
			}
			ip2dbg(("ire_add_mrtun: mrtun table is created\n"));
		}
		/* some other thread got it and created the table */
		mutex_exit(&ire_mrtun_lock);
	}

	/*
	 * Check for duplicate in the bucket and insert in the table
	 */
	irb_ptr = &(ip_mrtun_table[IRE_ADDR_HASH(ire->ire_in_src_addr,
	    IP_MRTUN_TABLE_SIZE)]);

	/*
	 * Start the atomic add of the ire. Grab the ill locks,
	 * ill_g_usesrc_lock and the bucket lock.
	 *
	 * If ipif or ill is changing ire_atomic_start() may queue the
	 * request and return EINPROGRESS.
	 */
	error = ire_atomic_start(irb_ptr, ire, q, mp, func);
	if (error != 0) {
		/*
		 * We don't know whether it is a valid ipif or not.
		 * So, set it to NULL. This assumes that the ire has not added
		 * a reference to the ipif.
		 */
		ire->ire_ipif = NULL;
		ire_delete(ire);
		ip1dbg(("ire_add_mrtun: ire_atomic_start failed\n"));
		*ire_p = NULL;
		return (error);
	}
	for (ire1 = irb_ptr->irb_ire; ire1 != NULL; ire1 = ire1->ire_next) {
		if (ire1->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		/* has anyone inserted the route in the meanwhile ? */
		if (ire1->ire_in_ill == ire->ire_in_ill &&
		    ire1->ire_in_src_addr == ire->ire_in_src_addr) {
			ip1dbg(("ire_add_mrtun: Duplicate entry exists\n"));
			IRE_REFHOLD(ire1);
			ire_atomic_end(irb_ptr, ire);
			ire_delete(ire);
			/* Return the old ire */
			*ire_p = ire1;
			return (0);
		}
	}

	/* Atomically set the ire_max_frag */
	max_frag = *ire->ire_max_fragp;
	ire->ire_max_fragp = NULL;
	ire->ire_max_frag = MIN(max_frag, IP_MAXPACKET);

	irep = (ire_t **)irb_ptr;
	if (*irep != NULL) {
		/* Find the last ire which matches ire_in_src_addr */
		ire1 = *irep;
		while (ire1->ire_in_src_addr == ire->ire_in_src_addr) {
			irep = &ire1->ire_next;
			ire1 = *irep;
			if (ire1 == NULL)
				break;
		}
	}
	ire1 = *irep;
	if (ire1 != NULL)
		ire1->ire_ptpn = &ire->ire_next;
	ire->ire_next = ire1;
	/* Link the new one in. */
	ire->ire_ptpn = irep;
	membar_producer();
	*irep = ire;
	ire->ire_bucket = irb_ptr;
	IRE_REFHOLD_LOCKED(ire);

	ip2dbg(("ire_add_mrtun: created and linked ire %p\n", (void *)*irep));

	/*
	 * Protect ire_mrtun_count and ill_mrtun_refcnt from
	 * another thread trying to add ire in the table
	 */
	mutex_enter(&ire_mrtun_lock);
	ire_mrtun_count++;
	mutex_exit(&ire_mrtun_lock);
	/*
	 * ill_mrtun_refcnt is protected by the ill_lock held via
	 * ire_atomic_start
	 */
	ire->ire_in_ill->ill_mrtun_refcnt++;

	if (ire->ire_ipif != NULL) {
		ire->ire_ipif->ipif_ire_cnt++;
		if (ire->ire_stq != NULL) {
			stq_ill = (ill_t *)ire->ire_stq->q_ptr;
			stq_ill->ill_ire_cnt++;
		}
	} else {
		ASSERT(ire->ire_stq == NULL);
	}

	ire_atomic_end(irb_ptr, ire);
	ire_fastpath(ire);
	*ire_p = ire;
	return (0);
}


/* Walks down the mrtun table */

void
ire_walk_ill_mrtun(uint_t match_flags, uint_t ire_type, pfv_t func, void *arg,
    ill_t *ill)
{
	irb_t	*irb;
	ire_t	*ire;
	int	i;
	int	ret;

	ASSERT((!(match_flags & (MATCH_IRE_WQ | MATCH_IRE_ILL |
	    MATCH_IRE_ILL_GROUP))) || (ill != NULL));
	ASSERT(match_flags == 0 || ire_type == IRE_MIPRTUN);

	mutex_enter(&ire_mrtun_lock);
	if (ire_mrtun_count == 0) {
		mutex_exit(&ire_mrtun_lock);
		return;
	}
	mutex_exit(&ire_mrtun_lock);

	ip2dbg(("ire_walk_ill_mrtun:walking the reverse tunnel table \n"));
	for (i = 0; i < IP_MRTUN_TABLE_SIZE; i++) {

		irb = &(ip_mrtun_table[i]);
		if (irb->irb_ire == NULL)
			continue;
		IRB_REFHOLD(irb);
		for (ire = irb->irb_ire; ire != NULL;
		    ire = ire->ire_next) {
			ASSERT(ire->ire_ipversion == IPV4_VERSION);
			if (match_flags != 0) {
				ret = ire_walk_ill_match(
				    match_flags, ire_type,
				    ire, ill, ALL_ZONES);
			}
			if (match_flags == 0 || ret)
				(*func)(ire, arg);
		}
		IRB_REFRELE(irb);
	}
}

/*
 * Source interface based lookup routine (IPV4 only).
 * This routine is called only when RTA_SRCIFP bitflag is set
 * by routing socket while adding/deleting the route and it is
 * also called from ip_rput() when packets arrive from an interface
 * for which ill_srcif_ref_cnt is positive. This function is useful
 * when a packet coming from one interface must be forwarded to another
 * designated interface to reach the correct node. This function is also
 * called from ip_newroute when the link-layer address of an ire is resolved.
 * We need to make sure that ip_newroute searches for IRE_IF_RESOLVER type
 * ires--thus the ire_type parameter is needed.
 */

ire_t *
ire_srcif_table_lookup(ipaddr_t dst_addr, int ire_type, ipif_t *ipif,
    ill_t *in_ill, int flags)
{
	irb_t	*irb_ptr;
	ire_t	*ire;
	irb_t	*ire_srcif_table;

	ASSERT(in_ill != NULL && !in_ill->ill_isv6);
	ASSERT(!(flags & (MATCH_IRE_ILL|MATCH_IRE_ILL_GROUP)) ||
	    (ipif != NULL && !ipif->ipif_isv6));

	/*
	 * No need to lock the ill since it is refheld by the caller of this
	 * function
	 */
	if (in_ill->ill_srcif_table == NULL) {
		return (NULL);
	}

	if (!(flags & MATCH_IRE_TYPE)) {
		flags |= MATCH_IRE_TYPE;
		ire_type = IRE_INTERFACE;
	}
	ire_srcif_table = in_ill->ill_srcif_table;
	irb_ptr = &ire_srcif_table[IRE_ADDR_HASH(dst_addr,
	    IP_SRCIF_TABLE_SIZE)];
	rw_enter(&irb_ptr->irb_lock, RW_READER);
	for (ire = irb_ptr->irb_ire; ire != NULL; ire = ire->ire_next) {
		if (ire->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		if (ire_match_args(ire, dst_addr, ire->ire_mask, 0,
		    ire_type, ipif, ire->ire_zoneid, 0, flags)) {
			IRE_REFHOLD(ire);
			rw_exit(&irb_ptr->irb_lock);
			return (ire);
		}
	}
	/* Not Found */
	rw_exit(&irb_ptr->irb_lock);
	return (NULL);
}


/*
 * Adds the ire into the special routing table which is hanging off of
 * the src_ipif->ipif_ill. It also increments the refcnt in the ill.
 * The forward table contains only IRE_IF_RESOLVER, IRE_IF_NORESOLVER
 * i,e. IRE_INTERFACE entries. Originally the dlureq_mp field is NULL
 * for IRE_IF_RESOLVER entry because we do not have the dst_addr's
 * link-layer address at the time of addition.
 * Upon resolving the address from ARP, dlureq_mp field is updated with
 * proper information in ire_update_srcif_v4.
 */
static int
ire_add_srcif_v4(ire_t **ire_p, queue_t *q, mblk_t *mp, ipsq_func_t func)
{
	ire_t	*ire1;
	irb_t	*ire_srcifp_table = NULL;
	irb_t	*irb_ptr = NULL;
	ire_t   **irep;
	ire_t   *ire;
	int	flags;
	int	i;
	ill_t	*stq_ill;
	uint_t	max_frag;
	int error = 0;

	ire = *ire_p;
	ASSERT(ire->ire_in_ill != NULL);
	ASSERT(ire->ire_ipversion == IPV4_VERSION);
	ASSERT(ire->ire_type == IRE_IF_NORESOLVER ||
	    ire->ire_type == IRE_IF_RESOLVER);

	ire->ire_mask = IP_HOST_MASK;
	/* Update ire_dlureq_mp with NULL value upon creation */
	if (ire->ire_type == IRE_IF_RESOLVER) {
		/*
		 * assign NULL now, it will be updated
		 * with correct value upon returning from
		 * ARP
		 */
		ire->ire_dlureq_mp = NULL;
	} else {
		ire->ire_dlureq_mp = ill_dlur_gen(NULL,
		    ire->ire_ipif->ipif_ill->ill_phys_addr_length,
		    ire->ire_ipif->ipif_ill->ill_sap,
		    ire->ire_ipif->ipif_ill->ill_sap_length);
	}
	/* Make sure the address is properly masked. */
	ire->ire_addr &= ire->ire_mask;

	ASSERT(ire->ire_max_fragp != NULL);
	max_frag = *ire->ire_max_fragp;
	ire->ire_max_fragp = NULL;
	ire->ire_max_frag = MIN(max_frag, IP_MAXPACKET);

	mutex_enter(&ire->ire_in_ill->ill_lock);
	if (ire->ire_in_ill->ill_srcif_table == NULL) {
		/* create the incoming interface based table */
		ire->ire_in_ill->ill_srcif_table =
		    (irb_t *)kmem_zalloc(IP_SRCIF_TABLE_SIZE *
			sizeof (irb_t), KM_NOSLEEP);
		if (ire->ire_in_ill->ill_srcif_table == NULL) {
			ip1dbg(("ire_add_srcif_v4: Allocation fail\n"));
			mutex_exit(&ire->ire_in_ill->ill_lock);
			ire_delete(ire);
			*ire_p = NULL;
			return (ENOMEM);
		}
		ire_srcifp_table = ire->ire_in_ill->ill_srcif_table;
		for (i = 0; i < IP_SRCIF_TABLE_SIZE; i++) {
			rw_init(&ire_srcifp_table[i].irb_lock, NULL,
			    RW_DEFAULT, NULL);
		}
		ip2dbg(("ire_add_srcif_v4: table created for ill %p\n",
		    (void *)ire->ire_in_ill));
	}
	/* Check for duplicate and insert */
	ASSERT(ire->ire_in_ill->ill_srcif_table != NULL);
	irb_ptr =
	    &(ire->ire_in_ill->ill_srcif_table[IRE_ADDR_HASH(ire->ire_addr,
	    IP_SRCIF_TABLE_SIZE)]);
	mutex_exit(&ire->ire_in_ill->ill_lock);
	flags = (MATCH_IRE_MASK | MATCH_IRE_TYPE | MATCH_IRE_GW);
	flags |= MATCH_IRE_IPIF;

	/*
	 * Start the atomic add of the ire. Grab the ill locks,
	 * ill_g_usesrc_lock and the bucket lock.
	 *
	 * If ipif or ill is changing ire_atomic_start() may queue the
	 * request and return EINPROGRESS.
	 */
	error = ire_atomic_start(irb_ptr, ire, q, mp, func);
	if (error != 0) {
		/*
		 * We don't know whether it is a valid ipif or not.
		 * So, set it to NULL. This assumes that the ire has not added
		 * a reference to the ipif.
		 */
		ire->ire_ipif = NULL;
		ire_delete(ire);
		ip1dbg(("ire_add_srcif_v4: ire_atomic_start failed\n"));
		*ire_p = NULL;
		return (error);
	}
	for (ire1 = irb_ptr->irb_ire; ire1 != NULL; ire1 = ire1->ire_next) {
		if (ire1->ire_marks & IRE_MARK_CONDEMNED)
			continue;
		if (ire1->ire_zoneid != ire->ire_zoneid)
			continue;
		/* Has anyone inserted route in the meanwhile ? */
		if (ire_match_args(ire1, ire->ire_addr, ire->ire_mask, 0,
		    ire->ire_type, ire->ire_ipif, ire->ire_zoneid, 0, flags)) {
			ip1dbg(("ire_add_srcif_v4 : Duplicate entry exists\n"));
			IRE_REFHOLD(ire1);
			ire_atomic_end(irb_ptr, ire);
			ire_delete(ire);
			/* Return old ire as in ire_add_v4 */
			*ire_p = ire1;
			return (0);
		}
	}
	irep = (ire_t **)irb_ptr;
	if (*irep != NULL) {
		/* Find the last ire which matches ire_addr */
		ire1 = *irep;
		while (ire1->ire_addr == ire->ire_addr) {
			irep = &ire1->ire_next;
			ire1 = *irep;
			if (ire1 == NULL)
				break;
		}
	}
	ire1 = *irep;
	if (ire1 != NULL)
		ire1->ire_ptpn = &ire->ire_next;
	ire->ire_next = ire1;
	/* Link the new one in. */
	ire->ire_ptpn = irep;
	membar_producer();
	*irep = ire;
	ire->ire_bucket = irb_ptr;
	IRE_REFHOLD_LOCKED(ire);

	/*
	 * Protect ire_in_ill->ill_srcif_refcnt and table reference count.
	 * Note, ire_atomic_start already grabs the ire_in_ill->ill_lock
	 * so ill_srcif_refcnt is already protected.
	 */
	ire->ire_in_ill->ill_srcif_refcnt++;
	mutex_enter(&ire_srcif_table_lock);
	ire_srcif_table_count++;
	mutex_exit(&ire_srcif_table_lock);
	irb_ptr->irb_ire_cnt++;
	if (ire->ire_ipif != NULL) {
		ire->ire_ipif->ipif_ire_cnt++;
		if (ire->ire_stq != NULL) {
			stq_ill = (ill_t *)ire->ire_stq->q_ptr;
			stq_ill->ill_ire_cnt++;
		}
	} else {
		ASSERT(ire->ire_stq == NULL);
	}

	ire_atomic_end(irb_ptr, ire);
	*ire_p = ire;
	return (0);
}


/*
 * This function is called by ire_add_then_send when ARP request comes
 * back to ip_wput->ire_add_then_send for resolved ire in the interface
 * based routing table. At this point, it only needs to update the resolver
 * information for the ire. The passed ire is returned to the caller as it
 * is the ire which is created as mblk.
 */

static ire_t *
ire_update_srcif_v4(ire_t *ire)
{
	ire_t   *ire1;
	irb_t	*irb;
	int	error;

	ASSERT(ire->ire_type != IRE_MIPRTUN &&
	    ire->ire_ipif->ipif_net_type == IRE_IF_RESOLVER);
	ASSERT(ire->ire_ipversion == IPV4_VERSION);

	/*
	 * This ire is from ARP. Update
	 * ire_dlureq_mp info
	 */
	ire1 = ire_srcif_table_lookup(ire->ire_addr,
	    IRE_IF_RESOLVER, ire->ire_ipif,
	    ire->ire_in_ill,
	    MATCH_IRE_ILL | MATCH_IRE_TYPE);
	if (ire1 == NULL) {
		/* Mobile node registration expired ? */
		ire_delete(ire);
		return (NULL);
	}
	irb = ire1->ire_bucket;
	ASSERT(irb != NULL);
	/*
	 * Start the atomic add of the ire. Grab the ill locks,
	 * ill_g_usesrc_lock and the bucket lock.
	 */
	error = ire_atomic_start(irb, ire1, NULL, NULL, NULL);
	if (error != 0) {
		/*
		 * We don't know whether it is a valid ipif or not.
		 * So, set it to NULL. This assumes that the ire has not added
		 * a reference to the ipif.
		 */
		ire->ire_ipif = NULL;
		ire_delete(ire);
		ip1dbg(("ire_update_srcif_v4: ire_atomic_start failed\n"));
		return (NULL);
	}
	ASSERT(ire->ire_max_fragp == NULL);
	ire->ire_max_frag = ire1->ire_max_frag;
	/*
	 * Update resolver information and
	 * send-to queue.
	 */
	ASSERT(ire->ire_dlureq_mp != NULL);
	ire1->ire_dlureq_mp = copyb(ire->ire_dlureq_mp);
	if (ire1->ire_dlureq_mp ==  NULL) {
		ip0dbg(("ire_update_srcif: copyb failed\n"));
		ire_refrele(ire1);
		ire_refrele(ire);
		ire_atomic_end(irb, ire1);
		return (NULL);
	}
	ire1->ire_stq = ire->ire_stq;

	ASSERT(ire->ire_fp_mp == NULL);

	ire_atomic_end(irb, ire1);
	ire_refrele(ire1);
	/* Return the passed ire */
	return (ire);   /* Update done */
}


/*
 * Check if another multirt route resolution is needed.
 * B_TRUE is returned is there remain a resolvable route,
 * or if no route for that dst is resolved yet.
 * B_FALSE is returned if all routes for that dst are resolved
 * or if the remaining unresolved routes are actually not
 * resolvable.
 * This only works in the global zone.
 */
boolean_t
ire_multirt_need_resolve(ipaddr_t dst)
{
	ire_t	*first_fire;
	ire_t	*first_cire;
	ire_t	*fire;
	ire_t	*cire;
	irb_t	*firb;
	irb_t	*cirb;
	int	unres_cnt = 0;
	boolean_t resolvable = B_FALSE;

	/* Retrieve the first IRE_HOST that matches the destination */
	first_fire = ire_ftable_lookup(dst, IP_HOST_MASK, 0, IRE_HOST, NULL,
	    NULL, ALL_ZONES, 0, MATCH_IRE_MASK | MATCH_IRE_TYPE);

	/* No route at all */
	if (first_fire == NULL) {
		return (B_TRUE);
	}

	firb = first_fire->ire_bucket;
	ASSERT(firb != NULL);

	/* Retrieve the first IRE_CACHE ire for that destination. */
	first_cire = ire_cache_lookup(dst, GLOBAL_ZONEID);

	/* No resolved route. */
	if (first_cire == NULL) {
		ire_refrele(first_fire);
		return (B_TRUE);
	}

	/*
	 * At least one route is resolved. Here we look through the forward
	 * and cache tables, to compare the number of declared routes
	 * with the number of resolved routes. The search for a resolvable
	 * route is performed only if at least one route remains
	 * unresolved.
	 */
	cirb = first_cire->ire_bucket;
	ASSERT(cirb != NULL);

	/* Count the number of routes to that dest that are declared. */
	IRB_REFHOLD(firb);
	for (fire = first_fire; fire != NULL; fire = fire->ire_next) {
		if (!(fire->ire_flags & RTF_MULTIRT))
			continue;
		if (fire->ire_addr != dst)
			continue;
		unres_cnt++;
	}
	IRB_REFRELE(firb);

	/* Then subtract the number of routes to that dst that are resolved */
	IRB_REFHOLD(cirb);
	for (cire = first_cire; cire != NULL; cire = cire->ire_next) {
		if (!(cire->ire_flags & RTF_MULTIRT))
			continue;
		if (cire->ire_addr != dst)
			continue;
		if (cire->ire_marks & (IRE_MARK_CONDEMNED | IRE_MARK_HIDDEN))
			continue;
		unres_cnt--;
	}
	IRB_REFRELE(cirb);

	/* At least one route is unresolved; search for a resolvable route. */
	if (unres_cnt > 0)
		resolvable = ire_multirt_lookup(&first_cire, &first_fire,
		    MULTIRT_USESTAMP | MULTIRT_CACHEGW);

	if (first_fire != NULL)
		ire_refrele(first_fire);

	if (first_cire != NULL)
		ire_refrele(first_cire);

	return (resolvable);
}


/*
 * Explore a forward_table bucket, starting from fire_arg.
 * fire_arg MUST be an IRE_HOST entry.
 *
 * Return B_TRUE and update *ire_arg and *fire_arg
 * if at least one resolvable route is found. *ire_arg
 * is the IRE entry for *fire_arg's gateway.
 *
 * Return B_FALSE otherwise (all routes are resolved or
 * the remaining unresolved routes are all unresolvable).
 *
 * The IRE selection relies on a priority mechanism
 * driven by the flags passed in by the caller.
 * The caller, such as ip_newroute_ipif(), can get the most
 * relevant ire at each stage of a multiple route resolution.
 *
 * The rules are:
 *
 * - if MULTIRT_CACHEGW is specified in flags, IRE_CACHETABLE
 *   ires are preferred for the gateway. This gives the highest
 *   priority to routes that can be resolved without using
 *   a resolver.
 *
 * - if MULTIRT_CACHEGW is not specified, or if MULTIRT_CACHEGW
 *   is specified but no IRE_CACHETABLE ire entry for the gateway
 *   is found, the following rules apply.
 *
 * - if MULTIRT_USESTAMP is specified in flags, IRE_INTERFACE
 *   ires for the gateway, that have not been tried since
 *   a configurable amount of time, are preferred.
 *   This applies when a resolver must be invoked for
 *   a missing route, but we don't want to use the resolver
 *   upon each packet emission. If no such resolver is found,
 *   B_FALSE is returned.
 *   The MULTIRT_USESTAMP flag can be combined with
 *   MULTIRT_CACHEGW.
 *
 * - if MULTIRT_USESTAMP is not specified in flags, the first
 *   unresolved but resolvable route is selected.
 *
 * - Otherwise, there is no resolvalble route, and
 *   B_FALSE is returned.
 *
 * At last, MULTIRT_SETSTAMP can be specified in flags to
 * request the timestamp of unresolvable routes to
 * be refreshed. This prevents the useless exploration
 * of those routes for a while, when MULTIRT_USESTAMP is used.
 *
 * This only works in the global zone.
 */
boolean_t
ire_multirt_lookup(ire_t **ire_arg, ire_t **fire_arg, uint32_t flags)
{
	clock_t	delta;
	ire_t	*best_fire = NULL;
	ire_t	*best_cire = NULL;
	ire_t	*first_fire;
	ire_t	*first_cire;
	ire_t	*fire;
	ire_t	*cire;
	irb_t	*firb = NULL;
	irb_t	*cirb = NULL;
	ire_t	*gw_ire;
	boolean_t	already_resolved;
	boolean_t	res;
	ipaddr_t	dst;
	ipaddr_t	gw;

	ip2dbg(("ire_multirt_lookup: *ire_arg %p, *fire_arg %p, flags %04x\n",
	    (void *)*ire_arg, (void *)*fire_arg, flags));

	ASSERT(ire_arg != NULL);
	ASSERT(fire_arg != NULL);

	/* Not an IRE_HOST ire; give up. */
	if ((*fire_arg == NULL) || ((*fire_arg)->ire_type != IRE_HOST)) {
		return (B_FALSE);
	}

	/* This is the first IRE_HOST ire for that destination. */
	first_fire = *fire_arg;
	firb = first_fire->ire_bucket;
	ASSERT(firb != NULL);

	dst = first_fire->ire_addr;

	ip2dbg(("ire_multirt_lookup: dst %08x\n", ntohl(dst)));

	/*
	 * Retrieve the first IRE_CACHE ire for that destination;
	 * if we don't find one, no route for that dest is
	 * resolved yet.
	 */
	first_cire = ire_cache_lookup(dst, GLOBAL_ZONEID);
	if (first_cire != NULL) {
		cirb = first_cire->ire_bucket;
	}

	ip2dbg(("ire_multirt_lookup: first_cire %p\n", (void *)first_cire));

	/*
	 * Search for a resolvable route, giving the top priority
	 * to routes that can be resolved without any call to the resolver.
	 */
	IRB_REFHOLD(firb);

	if (!CLASSD(dst)) {
		/*
		 * For all multiroute IRE_HOST ires for that destination,
		 * check if the route via the IRE_HOST's gateway is
		 * resolved yet.
		 */
		for (fire = first_fire; fire != NULL; fire = fire->ire_next) {

			if (!(fire->ire_flags & RTF_MULTIRT))
				continue;
			if (fire->ire_addr != dst)
				continue;

			gw = fire->ire_gateway_addr;

			ip2dbg(("ire_multirt_lookup: fire %p, "
			    "ire_addr %08x, ire_gateway_addr %08x\n",
			    (void *)fire, ntohl(fire->ire_addr), ntohl(gw)));

			already_resolved = B_FALSE;

			if (first_cire != NULL) {
				ASSERT(cirb != NULL);

				IRB_REFHOLD(cirb);
				/*
				 * For all IRE_CACHE ires for that
				 * destination.
				 */
				for (cire = first_cire;
				    cire != NULL;
				    cire = cire->ire_next) {

					if (!(cire->ire_flags & RTF_MULTIRT))
						continue;
					if (cire->ire_addr != dst)
						continue;
					if (cire->ire_marks &
					    (IRE_MARK_CONDEMNED |
						IRE_MARK_HIDDEN))
						continue;
					/*
					 * Check if the IRE_CACHE's gateway
					 * matches the IRE_HOST's gateway.
					 */
					if (cire->ire_gateway_addr == gw) {
						already_resolved = B_TRUE;
						break;
					}
				}
				IRB_REFRELE(cirb);
			}

			/*
			 * This route is already resolved;
			 * proceed with next one.
			 */
			if (already_resolved) {
				ip2dbg(("ire_multirt_lookup: found cire %p, "
				    "already resolved\n", (void *)cire));
				continue;
			}

			/*
			 * The route is unresolved; is it actually
			 * resolvable, i.e. is there a cache or a resolver
			 * for the gateway?
			 */
			gw_ire = ire_route_lookup(gw, 0, 0, 0, NULL, NULL,
			    ALL_ZONES, MATCH_IRE_RECURSIVE);

			ip2dbg(("ire_multirt_lookup: looked up gw_ire %p\n",
			    (void *)gw_ire));

			/*
			 * If gw_ire is typed IRE_CACHETABLE,
			 * this route can be resolved without any call to the
			 * resolver. If the MULTIRT_CACHEGW flag is set,
			 * give the top priority to this ire and exit the
			 * loop.
			 * This is typically the case when an ARP reply
			 * is processed through ip_wput_nondata().
			 */
			if ((flags & MULTIRT_CACHEGW) &&
			    (gw_ire != NULL) &&
			    (gw_ire->ire_type & IRE_CACHETABLE)) {
				/*
				 * Release the resolver associated to the
				 * previous candidate best ire, if any.
				 */
				if (best_cire != NULL) {
					ire_refrele(best_cire);
					ASSERT(best_fire != NULL);
				}

				best_fire = fire;
				best_cire = gw_ire;

				ip2dbg(("ire_multirt_lookup: found top prio "
				    "best_fire %p, best_cire %p\n",
				    (void *)best_fire, (void *)best_cire));
				break;
			}

			/*
			 * Compute the time elapsed since our preceding
			 * attempt to  resolve that route.
			 * If the MULTIRT_USESTAMP flag is set, we take that
			 * route into account only if this time interval
			 * exceeds ip_multirt_resolution_interval;
			 * this prevents us from attempting to resolve a
			 * broken route upon each sending of a packet.
			 */
			delta = lbolt - fire->ire_last_used_time;
			delta = TICK_TO_MSEC(delta);

			res = (boolean_t)
			    ((delta > ip_multirt_resolution_interval) ||
				(!(flags & MULTIRT_USESTAMP)));

			ip2dbg(("ire_multirt_lookup: fire %p, delta %lu, "
			    "res %d\n",
			    (void *)fire, delta, res));

			if (res) {
				/*
				 * We are here if MULTIRT_USESTAMP flag is set
				 * and the resolver for fire's gateway
				 * has not been tried since
				 * ip_multirt_resolution_interval, or if
				 * MULTIRT_USESTAMP is not set but gw_ire did
				 * not fill the conditions for MULTIRT_CACHEGW,
				 * or if neither MULTIRT_USESTAMP nor
				 * MULTIRT_CACHEGW are set.
				 */
				if (gw_ire != NULL) {
					if (best_fire == NULL) {
						ASSERT(best_cire == NULL);

						best_fire = fire;
						best_cire = gw_ire;

						ip2dbg(("ire_multirt_lookup:"
						    "found candidate "
						    "best_fire %p, "
						    "best_cire %p\n",
						    (void *)best_fire,
						    (void *)best_cire));

						/*
						 * If MULTIRT_CACHEGW is not
						 * set, we ignore the top
						 * priority ires that can
						 * be resolved without any
						 * call to the resolver;
						 * In that case, there is
						 * actually no need
						 * to continue the loop.
						 */
						if (!(flags &
						    MULTIRT_CACHEGW)) {
							break;
						}
						continue;
					}
				} else {
					/*
					 * No resolver for the gateway: the
					 * route is not resolvable.
					 * If the MULTIRT_SETSTAMP flag is
					 * set, we stamp the IRE_HOST ire,
					 * so we will not select it again
					 * during this resolution interval.
					 */
					if (flags & MULTIRT_SETSTAMP)
						fire->ire_last_used_time =
						    lbolt;
				}
			}

			if (gw_ire != NULL)
				ire_refrele(gw_ire);
		}
	} else { /* CLASSD(dst) */

		for (fire = first_fire;
		    fire != NULL;
		    fire = fire->ire_next) {

			if (!(fire->ire_flags & RTF_MULTIRT))
				continue;
			if (fire->ire_addr != dst)
				continue;

			already_resolved = B_FALSE;

			gw = fire->ire_gateway_addr;

			gw_ire = ire_ftable_lookup(gw, 0, 0, IRE_INTERFACE,
			    NULL, NULL, ALL_ZONES, 0,
			    MATCH_IRE_RECURSIVE | MATCH_IRE_TYPE);

			/* No resolver for the gateway; we skip this ire. */
			if (gw_ire == NULL) {
				continue;
			}

			if (first_cire != NULL) {

				IRB_REFHOLD(cirb);
				/*
				 * For all IRE_CACHE ires for that
				 * destination.
				 */
				for (cire = first_cire;
				    cire != NULL;
				    cire = cire->ire_next) {

					if (!(cire->ire_flags & RTF_MULTIRT))
						continue;
					if (cire->ire_addr != dst)
						continue;
					if (cire->ire_marks &
					    (IRE_MARK_CONDEMNED |
						IRE_MARK_HIDDEN))
						continue;

					/*
					 * Cache entries are linked to the
					 * parent routes using the parent handle
					 * (ire_phandle). If no cache entry has
					 * the same handle as fire, fire is
					 * still unresolved.
					 */
					ASSERT(cire->ire_phandle != 0);
					if (cire->ire_phandle ==
					    fire->ire_phandle) {
						already_resolved = B_TRUE;
						break;
					}
				}
				IRB_REFRELE(cirb);
			}

			/*
			 * This route is already resolved; proceed with
			 * next one.
			 */
			if (already_resolved) {
				ire_refrele(gw_ire);
				continue;
			}

			/*
			 * Compute the time elapsed since our preceding
			 * attempt to resolve that route.
			 * If the MULTIRT_USESTAMP flag is set, we take
			 * that route into account only if this time
			 * interval exceeds ip_multirt_resolution_interval;
			 * this prevents us from attempting to resolve a
			 * broken route upon each sending of a packet.
			 */
			delta = lbolt - fire->ire_last_used_time;
			delta = TICK_TO_MSEC(delta);

			res = (boolean_t)
			    ((delta > ip_multirt_resolution_interval) ||
			    (!(flags & MULTIRT_USESTAMP)));

			ip3dbg(("ire_multirt_lookup: fire %p, delta %lx, "
			    "flags %04x, res %d\n",
			    (void *)fire, delta, flags, res));

			if (res) {
				if (best_cire != NULL) {
					/*
					 * Release the resolver associated
					 * to the preceding candidate best
					 * ire, if any.
					 */
					ire_refrele(best_cire);
					ASSERT(best_fire != NULL);
				}
				best_fire = fire;
				best_cire = gw_ire;
				continue;
			}

			ire_refrele(gw_ire);
		}
	}

	if (best_fire != NULL) {
		IRE_REFHOLD(best_fire);
	}
	IRB_REFRELE(firb);

	/* Release the first IRE_CACHE we initially looked up, if any. */
	if (first_cire != NULL)
		ire_refrele(first_cire);

	/* Found a resolvable route. */
	if (best_fire != NULL) {
		ASSERT(best_cire != NULL);

		if (*fire_arg != NULL)
			ire_refrele(*fire_arg);
		if (*ire_arg != NULL)
			ire_refrele(*ire_arg);

		/*
		 * Update the passed-in arguments with the
		 * resolvable multirt route we found.
		 */
		*fire_arg = best_fire;
		*ire_arg = best_cire;

		ip2dbg(("ire_multirt_lookup: returning B_TRUE, "
		    "*fire_arg %p, *ire_arg %p\n",
		    (void *)best_fire, (void *)best_cire));

		return (B_TRUE);
	}

	ASSERT(best_cire == NULL);

	ip2dbg(("ire_multirt_lookup: returning B_FALSE, *fire_arg %p, "
	    "*ire_arg %p\n",
	    (void *)*fire_arg, (void *)*ire_arg));

	/* No resolvable route. */
	return (B_FALSE);
}

/*
 * Find an IRE_OFFSUBNET IRE entry for the multicast address 'group'
 * that goes through 'ipif'. As a fallback, a route that goes through
 * ipif->ipif_ill can be returned.
 */
ire_t *
ipif_lookup_multi_ire(ipif_t *ipif, ipaddr_t group)
{
	ire_t	*ire;
	ire_t	*save_ire = NULL;
	ire_t   *gw_ire;
	irb_t   *irb;
	ipaddr_t gw_addr;
	int	match_flags = MATCH_IRE_TYPE | MATCH_IRE_ILL;

	ASSERT(CLASSD(group));

	ire = ire_ftable_lookup(group, 0, 0, 0, NULL, NULL, ALL_ZONES, 0,
	    MATCH_IRE_DEFAULT);

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

	irb = ire->ire_bucket;
	ASSERT(irb);

	IRB_REFHOLD(irb);
	ire_refrele(ire);
	for (ire = irb->irb_ire; ire != NULL; ire = ire->ire_next) {
		if (ire->ire_addr != group ||
		    ipif->ipif_zoneid != ire->ire_zoneid) {
			continue;
		}

		switch (ire->ire_type) {
		case IRE_DEFAULT:
		case IRE_PREFIX:
		case IRE_HOST:
			gw_addr = ire->ire_gateway_addr;
			gw_ire = ire_ftable_lookup(gw_addr, 0, 0, IRE_INTERFACE,
			    ipif, NULL, ALL_ZONES, 0, match_flags);

			if (gw_ire != NULL) {
				if (save_ire != NULL) {
					ire_refrele(save_ire);
				}
				IRE_REFHOLD(ire);
				if (gw_ire->ire_ipif == ipif) {
					ire_refrele(gw_ire);

					IRB_REFRELE(irb);
					return (ire);
				}
				ire_refrele(gw_ire);
				save_ire = ire;
			}
			break;
		case IRE_IF_NORESOLVER:
		case IRE_IF_RESOLVER:
			if (ire->ire_ipif == ipif) {
				if (save_ire != NULL) {
					ire_refrele(save_ire);
				}
				IRE_REFHOLD(ire);

				IRB_REFRELE(irb);
				return (ire);
			}
			break;
		}
	}
	IRB_REFRELE(irb);

	return (save_ire);
}

/*
 * The purpose of the next two functions is to provide some external access to
 * routing/l2 lookup functionality while hiding the implementation of routing
 * and interface data structures (IRE/ILL).  Thus, interfaces are passed/
 * returned by name instead of by ILL reference.  These functions are used by
 * IP Filter.
 * Return a link layer header suitable for an IP packet being sent to the
 * dst_addr IP address.  The interface associated with the route is put into
 * ifname, which must be a buffer of LIFNAMSIZ bytes.  The dst_addr is the
 * packet's ultimate destination address, not a router address.
 *
 * This function is used when the caller wants to know the outbound interface
 * and MAC header for a packet given only the address.
 */
mblk_t *
ip_nexthop_route(const struct sockaddr *target, char *ifname)
{
	struct nce_s *nce;
	ire_t *dir;
	ill_t *ill;
	mblk_t *mp;

	/* parameter sanity */
	if (ifname == NULL || target == NULL)
		return (NULL);

	/* Find the route entry, if it exists. */
	switch (target->sa_family) {
	case AF_INET:
		dir = ire_route_lookup(
		    ((struct sockaddr_in *)target)->sin_addr.s_addr,
		    0xffffffff,
		    0, 0, NULL, NULL, ALL_ZONES,
		    MATCH_IRE_DSTONLY|MATCH_IRE_DEFAULT|MATCH_IRE_RECURSIVE);
		break;
	case AF_INET6:
		dir = ire_route_lookup_v6(
		    &((struct sockaddr_in6 *)target)->sin6_addr,
		    NULL,
		    0, 0, NULL, NULL, ALL_ZONES,
		    MATCH_IRE_DSTONLY|MATCH_IRE_DEFAULT|MATCH_IRE_RECURSIVE);
		if ((dir != NULL) && (dir->ire_nce == NULL)) {
			ire_refrele(dir);
			dir = NULL;
		}
		break;
	default:
		dir = NULL;
		break;
	}


	if (dir == NULL)
		return (NULL);

	/* Map the IRE to an ILL so we can fill in ifname. */
	ill = ire_to_ill(dir);
	if (ill == NULL) {
		ire_refrele(dir);
		return (NULL);
	}
	(void) strncpy(ifname, ill->ill_name, LIFNAMSIZ);

	/* Return a copy of the header to the caller. */
	switch (target->sa_family) {
	case AF_INET :
		if (dir->ire_fp_mp != NULL) {
			if ((mp = dupb(dir->ire_fp_mp)) == NULL)
				mp = copyb(dir->ire_fp_mp);
		} else if (dir->ire_dlureq_mp != NULL) {
			if ((mp = dupb(dir->ire_dlureq_mp)) == NULL)
				mp = copyb(dir->ire_dlureq_mp);
		} else {
			mp = NULL;
		}
		break;
	case AF_INET6 :
		nce = dir->ire_nce;
		if (nce->nce_fp_mp != NULL) {
			if ((mp = dupb(nce->nce_fp_mp)) == NULL)
				mp = copyb(nce->nce_fp_mp);
		} else if (nce->nce_res_mp != NULL) {
			if ((mp = dupb(nce->nce_res_mp)) == NULL)
				mp = copyb(nce->nce_res_mp);
		} else {
			mp = NULL;
		}
		break;
	}

	ire_refrele(dir);
	return (mp);
}


/*
 * Return a link layer header suitable for an IP packet being sent to the
 * dst_addr IP address on the specified output interface.  The dst_addr
 * may be the packet's ultimate destination or a predetermined next hop
 * router's address.
 * ifname must be nul-terminated.
 *
 * This function is used when the caller knows the outbound interface (usually
 * because it was specified by policy) and only needs the MAC header for a
 * packet.
 */
mblk_t *
ip_nexthop(const struct sockaddr *target, const char *ifname)
{
	struct nce_s *nce;
	ill_walk_context_t ctx;
	t_uscalar_t sap;
	ire_t *dir;
	ill_t *ill;
	mblk_t *mp;

	/* parameter sanity */
	if (ifname == NULL || target == NULL)
		return (NULL);

	switch (target->sa_family) {
	case AF_INET :
		sap = IP_DL_SAP;
		break;
	case AF_INET6 :
		sap = IP6_DL_SAP;
		break;
	default:
		return (NULL);
	}

	/* Lock ill_g_lock before walking through the list */
	rw_enter(&ill_g_lock, RW_READER);
	/*
	 * Can we find the interface name among those currently configured?
	 */
	for (ill = ILL_START_WALK_ALL(&ctx); ill != NULL;
	    ill = ill_next(&ctx, ill)) {
		if ((strcmp(ifname, ill->ill_name) == 0) &&
		    (ill->ill_sap == sap))
			break;
	}
	if (ill == NULL || ill->ill_ipif == NULL) {
		rw_exit(&ill_g_lock);
		return (NULL);
	}

	mutex_enter(&ill->ill_lock);
	if (!ILL_CAN_LOOKUP(ill)) {
		mutex_exit(&ill->ill_lock);
		rw_exit(&ill_g_lock);
		return (NULL);
	}
	ill_refhold_locked(ill);
	mutex_exit(&ill->ill_lock);
	rw_exit(&ill_g_lock);

	/* Find the resolver entry, if it exists. */
	switch (target->sa_family) {
	case AF_INET:
		dir = ire_route_lookup(
			((struct sockaddr_in *)target)->sin_addr.s_addr,
			0xffffffff,
			0, 0, ill->ill_ipif, NULL, ALL_ZONES,
			MATCH_IRE_DSTONLY|MATCH_IRE_DEFAULT|
			MATCH_IRE_RECURSIVE|MATCH_IRE_IPIF);
		break;
	case AF_INET6:
		dir = ire_route_lookup_v6(
			&((struct sockaddr_in6 *)target)->sin6_addr, NULL,
			0, 0, ill->ill_ipif, NULL, ALL_ZONES,
			MATCH_IRE_DSTONLY|MATCH_IRE_DEFAULT|
			MATCH_IRE_RECURSIVE|MATCH_IRE_IPIF);
		if ((dir != NULL) && (dir->ire_nce == NULL)) {
			ire_refrele(dir);
			dir = NULL;
		}
		break;
	default:
		dir = NULL;
		break;
	}

	ill_refrele(ill);

	if (dir == NULL)
		return (NULL);

	/* Return a copy of the header to the caller. */
	switch (target->sa_family) {
	case AF_INET :
		if (dir->ire_fp_mp != NULL) {
			if ((mp = dupb(dir->ire_fp_mp)) == NULL)
				mp = copyb(dir->ire_fp_mp);
		} else if (dir->ire_dlureq_mp != NULL) {
			if ((mp = dupb(dir->ire_dlureq_mp)) == NULL)
				mp = copyb(dir->ire_dlureq_mp);
		} else {
			mp = NULL;
		}
		break;
	case AF_INET6 :
		nce = dir->ire_nce;
		if (nce->nce_fp_mp != NULL) {
			if ((mp = dupb(nce->nce_fp_mp)) == NULL)
				mp = copyb(nce->nce_fp_mp);
		} else if (nce->nce_res_mp != NULL) {
			if ((mp = dupb(nce->nce_res_mp)) == NULL)
				mp = copyb(nce->nce_res_mp);
		} else {
			mp = NULL;
		}
		break;
	}

	ire_refrele(dir);
	return (mp);
}

/*
 * IRE iterator for inbound and loopback broadcast processing.
 * Given an IRE_BROADCAST ire, walk the ires with the same destination
 * address, but skip over the passed-in ire. Returns the next ire without
 * a hold - assumes that the caller holds a reference on the IRE bucket.
 */
ire_t *
ire_get_next_bcast_ire(ire_t *curr, ire_t *ire)
{
	ill_t *ill;

	if (curr == NULL) {
		for (curr = ire->ire_bucket->irb_ire; curr != NULL;
		    curr = curr->ire_next) {
			if (curr->ire_addr == ire->ire_addr)
				break;
		}
	} else {
		curr = curr->ire_next;
	}
	ill = ire_to_ill(ire);
	for (; curr != NULL; curr = curr->ire_next) {
		if (curr->ire_addr != ire->ire_addr) {
			/*
			 * All the IREs to a given destination are contiguous;
			 * break out once the address doesn't match.
			 */
			break;
		}
		if (curr == ire) {
			/* skip over the passed-in ire */
			continue;
		}
		if ((curr->ire_stq != NULL && ire->ire_stq == NULL) ||
		    (curr->ire_stq == NULL && ire->ire_stq != NULL)) {
			/*
			 * If the passed-in ire is loopback, skip over
			 * non-loopback ires and vice versa.
			 */
			continue;
		}
		if (ire_to_ill(curr) != ill) {
			/* skip over IREs going through a different interface */
			continue;
		}
		if (curr->ire_marks & IRE_MARK_CONDEMNED) {
			/* skip over deleted IREs */
			continue;
		}
		return (curr);
	}
	return (NULL);
}

/*
 * IRE iterator used by ire_ftable_lookup[_v6]() to process multiple default
 * routes. Given a starting point in the hash list (ire_origin), walk the IREs
 * in the bucket skipping default interface routes and deleted entries.
 * Returns the next IRE (unheld), or NULL when we're back to the starting point.
 * Assumes that the caller holds a reference on the IRE bucket.
 */
ire_t *
ire_get_next_default_ire(ire_t *ire, ire_t *ire_origin)
{
	ASSERT(ire_origin->ire_bucket != NULL);
	ASSERT(ire != NULL);

	do {
		ire = ire->ire_next;
		if (ire == NULL)
			ire = ire_origin->ire_bucket->irb_ire;
		if (ire == ire_origin)
			return (NULL);
	} while ((ire->ire_type & IRE_INTERFACE) ||
	    (ire->ire_marks & IRE_MARK_CONDEMNED));
	ASSERT(ire != NULL);
	return (ire);
}

#ifdef IRE_DEBUG
th_trace_t *
th_trace_ire_lookup(ire_t *ire)
{
	int bucket_id;
	th_trace_t *th_trace;

	ASSERT(MUTEX_HELD(&ire->ire_lock));

	bucket_id = IP_TR_HASH(curthread);
	ASSERT(bucket_id < IP_TR_HASH_MAX);

	for (th_trace = ire->ire_trace[bucket_id]; th_trace != NULL;
	    th_trace = th_trace->th_next) {
		if (th_trace->th_id == curthread)
			return (th_trace);
	}
	return (NULL);
}

void
ire_trace_ref(ire_t *ire)
{
	int bucket_id;
	th_trace_t *th_trace;

	/*
	 * Attempt to locate the trace buffer for the curthread.
	 * If it does not exist, then allocate a new trace buffer
	 * and link it in list of trace bufs for this ipif, at the head
	 */
	mutex_enter(&ire->ire_lock);
	if (ire->ire_trace_disable == B_TRUE) {
		mutex_exit(&ire->ire_lock);
		return;
	}
	th_trace = th_trace_ire_lookup(ire);
	if (th_trace == NULL) {
		bucket_id = IP_TR_HASH(curthread);
		th_trace = (th_trace_t *)kmem_zalloc(sizeof (th_trace_t),
		    KM_NOSLEEP);
		if (th_trace == NULL) {
			ire->ire_trace_disable = B_TRUE;
			mutex_exit(&ire->ire_lock);
			ire_trace_inactive(ire);
			return;
		}

		th_trace->th_id = curthread;
		th_trace->th_next = ire->ire_trace[bucket_id];
		th_trace->th_prev = &ire->ire_trace[bucket_id];
		if (th_trace->th_next != NULL)
			th_trace->th_next->th_prev = &th_trace->th_next;
		ire->ire_trace[bucket_id] = th_trace;
	}
	ASSERT(th_trace->th_refcnt < TR_BUF_MAX - 1);
	th_trace->th_refcnt++;
	th_trace_rrecord(th_trace);
	mutex_exit(&ire->ire_lock);
}

void
ire_trace_free(th_trace_t *th_trace)
{
	/* unlink th_trace and free it */
	*th_trace->th_prev = th_trace->th_next;
	if (th_trace->th_next != NULL)
		th_trace->th_next->th_prev = th_trace->th_prev;
	th_trace->th_next = NULL;
	th_trace->th_prev = NULL;
	kmem_free(th_trace, sizeof (th_trace_t));
}

void
ire_untrace_ref(ire_t *ire)
{
	th_trace_t *th_trace;

	mutex_enter(&ire->ire_lock);

	if (ire->ire_trace_disable == B_TRUE) {
		mutex_exit(&ire->ire_lock);
		return;
	}

	th_trace = th_trace_ire_lookup(ire);
	ASSERT(th_trace != NULL && th_trace->th_refcnt > 0);
	th_trace_rrecord(th_trace);
	th_trace->th_refcnt--;

	if (th_trace->th_refcnt == 0)
		ire_trace_free(th_trace);

	mutex_exit(&ire->ire_lock);
}

static void
ire_trace_inactive(ire_t *ire)
{
	th_trace_t *th_trace;
	int i;

	mutex_enter(&ire->ire_lock);
	for (i = 0; i < IP_TR_HASH_MAX; i++) {
		while (ire->ire_trace[i] != NULL) {
			th_trace = ire->ire_trace[i];

			/* unlink th_trace and free it */
			ire->ire_trace[i] = th_trace->th_next;
			if (th_trace->th_next != NULL)
				th_trace->th_next->th_prev =
				    &ire->ire_trace[i];

			th_trace->th_next = NULL;
			th_trace->th_prev = NULL;
			kmem_free(th_trace, sizeof (th_trace_t));
		}
	}

	mutex_exit(&ire->ire_lock);
}

/* ARGSUSED */
void
ire_thread_exit(ire_t *ire, caddr_t arg)
{
	th_trace_t	*th_trace;

	mutex_enter(&ire->ire_lock);
	th_trace = th_trace_ire_lookup(ire);
	if (th_trace == NULL) {
		mutex_exit(&ire->ire_lock);
		return;
	}
	ASSERT(th_trace->th_refcnt == 0);

	ire_trace_free(th_trace);
	mutex_exit(&ire->ire_lock);
}

#endif