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

/*
 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
 *
 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
 * Copyright 2019 Joyent, Inc.
 * Copyright 2024 Oxide Computer Company
 */
/* Copyright (c) 1990 Mentat Inc. */

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/dlpi.h>
#include <sys/stropts.h>
#include <sys/sysmacros.h>
#include <sys/strsubr.h>
#include <sys/strlog.h>
#include <sys/strsun.h>
#include <sys/zone.h>
#define _SUN_TPI_VERSION 2
#include <sys/tihdr.h>
#include <sys/xti_inet.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/kobj.h>
#include <sys/modctl.h>
#include <sys/atomic.h>
#include <sys/policy.h>
#include <sys/priv.h>

#include <sys/systm.h>
#include <sys/param.h>
#include <sys/kmem.h>
#include <sys/sdt.h>
#include <sys/socket.h>
#include <sys/vtrace.h>
#include <sys/isa_defs.h>
#include <sys/mac.h>
#include <sys/mac_client.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <net/route.h>
#include <sys/sockio.h>
#include <netinet/in.h>
#include <net/if_dl.h>

#include <inet/common.h>
#include <inet/mi.h>
#include <inet/mib2.h>
#include <inet/nd.h>
#include <inet/arp.h>
#include <inet/snmpcom.h>
#include <inet/kstatcom.h>

#include <netinet/igmp_var.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet/sctp.h>

#include <inet/ip.h>
#include <inet/ip_impl.h>
#include <inet/ip6.h>
#include <inet/ip6_asp.h>
#include <inet/optcom.h>
#include <inet/tcp.h>
#include <inet/tcp_impl.h>
#include <inet/ip_multi.h>
#include <inet/ip_if.h>
#include <inet/ip_ire.h>
#include <inet/ip_ftable.h>
#include <inet/ip_rts.h>
#include <inet/ip_ndp.h>
#include <inet/ip_listutils.h>
#include <netinet/igmp.h>
#include <netinet/ip_mroute.h>
#include <inet/ipp_common.h>

#include <net/pfkeyv2.h>
#include <inet/sadb.h>
#include <inet/ipsec_impl.h>
#include <inet/ipdrop.h>
#include <inet/ip_netinfo.h>
#include <inet/ilb_ip.h>
#include <sys/squeue_impl.h>
#include <sys/squeue.h>

#include <sys/ethernet.h>
#include <net/if_types.h>
#include <sys/cpuvar.h>

#include <ipp/ipp.h>
#include <ipp/ipp_impl.h>
#include <ipp/ipgpc/ipgpc.h>

#include <sys/pattr.h>
#include <inet/ipclassifier.h>
#include <inet/sctp_ip.h>
#include <inet/sctp/sctp_impl.h>
#include <inet/udp_impl.h>
#include <sys/sunddi.h>

#include <sys/tsol/label.h>
#include <sys/tsol/tnet.h>

#include <sys/clock_impl.h>     /* For LBOLT_FASTPATH{,64} */

#ifdef  DEBUG
extern boolean_t skip_sctp_cksum;
#endif

static void     ip_input_local_v4(ire_t *, mblk_t *, ipha_t *,
    ip_recv_attr_t *);

static void     ip_input_broadcast_v4(ire_t *, mblk_t *, ipha_t *,
    ip_recv_attr_t *);
static void     ip_input_multicast_v4(ire_t *, mblk_t *, ipha_t *,
    ip_recv_attr_t *);

/*
 * Direct read side procedure capable of dealing with chains. GLDv3 based
 * drivers call this function directly with mblk chains while STREAMS
 * read side procedure ip_rput() calls this for single packet with ip_ring
 * set to NULL to process one packet at a time.
 *
 * The ill will always be valid if this function is called directly from
 * the driver.
 *
 * If this chain is part of a VLAN stream, then the VLAN tag is
 * stripped from the MAC header before being delivered to this
 * function.
 *
 * If the IP header in packet is not 32-bit aligned, every message in the
 * chain will be aligned before further operations. This is required on SPARC
 * platform.
 */
void
ip_input(ill_t *ill, ill_rx_ring_t *ip_ring, mblk_t *mp_chain,
    struct mac_header_info_s *mhip)
{
        (void) ip_input_common_v4(ill, ip_ring, mp_chain, mhip, NULL, NULL,
            NULL);
}

/*
 * ip_accept_tcp() - This function is called by the squeue when it retrieves
 * a chain of packets in the poll mode. The packets have gone through the
 * data link processing but not IP processing. For performance and latency
 * reasons, the squeue wants to process the chain in line instead of feeding
 * it back via ip_input path.
 *
 * We set up the ip_recv_attr_t with IRAF_TARGET_SQP to that ip_fanout_v4
 * will pass back any TCP packets matching the target sqp to
 * ip_input_common_v4 using ira_target_sqp_mp. Other packets are handled by
 * ip_input_v4 and ip_fanout_v4 as normal.
 * The TCP packets that match the target squeue are returned to the caller
 * as a b_next chain after each packet has been prepend with an mblk
 * from ip_recv_attr_to_mblk.
 */
mblk_t *
ip_accept_tcp(ill_t *ill, ill_rx_ring_t *ip_ring, squeue_t *target_sqp,
    mblk_t *mp_chain, mblk_t **last, uint_t *cnt)
{
        return (ip_input_common_v4(ill, ip_ring, mp_chain, NULL, target_sqp,
            last, cnt));
}

/*
 * Used by ip_input and ip_accept_tcp
 * The last three arguments are only used by ip_accept_tcp, and mhip is
 * only used by ip_input.
 */
mblk_t *
ip_input_common_v4(ill_t *ill, ill_rx_ring_t *ip_ring, mblk_t *mp_chain,
    struct mac_header_info_s *mhip, squeue_t *target_sqp,
    mblk_t **last, uint_t *cnt)
{
        mblk_t          *mp;
        ipha_t          *ipha;
        ip_recv_attr_t  iras;   /* Receive attributes */
        rtc_t           rtc;
        iaflags_t       chain_flags = 0;        /* Fixed for chain */
        mblk_t          *ahead = NULL;  /* Accepted head */
        mblk_t          *atail = NULL;  /* Accepted tail */
        uint_t          acnt = 0;       /* Accepted count */

        ASSERT(mp_chain != NULL);
        ASSERT(ill != NULL);

        /* These ones do not change as we loop over packets */
        iras.ira_ill = iras.ira_rill = ill;
        iras.ira_ruifindex = ill->ill_phyint->phyint_ifindex;
        iras.ira_rifindex = iras.ira_ruifindex;
        iras.ira_sqp = NULL;
        iras.ira_ring = ip_ring;
        /* For ECMP and outbound transmit ring selection */
        iras.ira_xmit_hint = ILL_RING_TO_XMIT_HINT(ip_ring);

        iras.ira_target_sqp = target_sqp;
        iras.ira_target_sqp_mp = NULL;
        if (target_sqp != NULL)
                chain_flags |= IRAF_TARGET_SQP;

        /*
         * We try to have a mhip pointer when possible, but
         * it might be NULL in some cases. In those cases we
         * have to assume unicast.
         */
        iras.ira_mhip = mhip;
        iras.ira_flags = 0;
        if (mhip != NULL) {
                switch (mhip->mhi_dsttype) {
                case MAC_ADDRTYPE_MULTICAST :
                        chain_flags |= IRAF_L2DST_MULTICAST;
                        break;
                case MAC_ADDRTYPE_BROADCAST :
                        chain_flags |= IRAF_L2DST_BROADCAST;
                        break;
                }
        }

        /*
         * Initialize the one-element route cache.
         *
         * We do ire caching from one iteration to
         * another. In the event the packet chain contains
         * all packets from the same dst, this caching saves
         * an ire_route_recursive for each of the succeeding
         * packets in a packet chain.
         */
        rtc.rtc_ire = NULL;
        rtc.rtc_ipaddr = INADDR_ANY;

        /* Loop over b_next */
        for (mp = mp_chain; mp != NULL; mp = mp_chain) {
                mp_chain = mp->b_next;
                mp->b_next = NULL;

                ASSERT(DB_TYPE(mp) == M_DATA);


                /*
                 * if db_ref > 1 then copymsg and free original. Packet
                 * may be changed and we do not want the other entity
                 * who has a reference to this message to trip over the
                 * changes. This is a blind change because trying to
                 * catch all places that might change the packet is too
                 * difficult.
                 *
                 * This corresponds to the fast path case, where we have
                 * a chain of M_DATA mblks.  We check the db_ref count
                 * of only the 1st data block in the mblk chain. There
                 * doesn't seem to be a reason why a device driver would
                 * send up data with varying db_ref counts in the mblk
                 * chain. In any case the Fast path is a private
                 * interface, and our drivers don't do such a thing.
                 * Given the above assumption, there is no need to walk
                 * down the entire mblk chain (which could have a
                 * potential performance problem)
                 *
                 * The "(DB_REF(mp) > 1)" check was moved from ip_rput()
                 * to here because of exclusive ip stacks and vnics.
                 * Packets transmitted from exclusive stack over vnic
                 * can have db_ref > 1 and when it gets looped back to
                 * another vnic in a different zone, you have ip_input()
                 * getting dblks with db_ref > 1. So if someone
                 * complains of TCP performance under this scenario,
                 * take a serious look here on the impact of copymsg().
                 */
                if (DB_REF(mp) > 1) {
                        if ((mp = ip_fix_dbref(mp, &iras)) == NULL) {
                                /* mhip might point into 1st packet in chain */
                                iras.ira_mhip = NULL;
                                continue;
                        }
                }

                /*
                 * IP header ptr not aligned?
                 * OR IP header not complete in first mblk
                 */
                ipha = (ipha_t *)mp->b_rptr;
                if (!OK_32PTR(ipha) || MBLKL(mp) < IP_SIMPLE_HDR_LENGTH) {
                        mp = ip_check_and_align_header(mp, IP_SIMPLE_HDR_LENGTH,
                            &iras);
                        if (mp == NULL) {
                                /* mhip might point into 1st packet in chain */
                                iras.ira_mhip = NULL;
                                continue;
                        }
                        ipha = (ipha_t *)mp->b_rptr;
                }

                /* Protect against a mix of Ethertypes and IP versions */
                if (IPH_HDR_VERSION(ipha) != IPV4_VERSION) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInHdrErrors);
                        ip_drop_input("ipIfStatsInHdrErrors", mp, ill);
                        freemsg(mp);
                        /* mhip might point into 1st packet in the chain. */
                        iras.ira_mhip = NULL;
                        continue;
                }

                /*
                 * Check for Martian addrs; we have to explicitly
                 * test for for zero dst since this is also used as
                 * an indication that the rtc is not used.
                 */
                if (ipha->ipha_dst == INADDR_ANY) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInAddrErrors);
                        ip_drop_input("ipIfStatsInAddrErrors", mp, ill);
                        freemsg(mp);
                        /* mhip might point into 1st packet in the chain. */
                        iras.ira_mhip = NULL;
                        continue;
                }

                /*
                 * Keep L2SRC from a previous packet in chain since mhip
                 * might point into an earlier packet in the chain.
                 * Keep IRAF_VERIFIED_SRC to avoid redoing broadcast
                 * source check in forwarding path.
                 */
                chain_flags |= (iras.ira_flags &
                    (IRAF_L2SRC_SET|IRAF_VERIFIED_SRC));

                iras.ira_flags = IRAF_IS_IPV4 | IRAF_VERIFY_IP_CKSUM |
                    IRAF_VERIFY_ULP_CKSUM | chain_flags;
                iras.ira_free_flags = 0;
                iras.ira_cred = NULL;
                iras.ira_cpid = NOPID;
                iras.ira_tsl = NULL;
                iras.ira_zoneid = ALL_ZONES;    /* Default for forwarding */

                /*
                 * We must count all incoming packets, even if they end
                 * up being dropped later on. Defer counting bytes until
                 * we have the whole IP header in first mblk.
                 */
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInReceives);

                iras.ira_pktlen = ntohs(ipha->ipha_length);
                UPDATE_MIB(ill->ill_ip_mib, ipIfStatsHCInOctets,
                    iras.ira_pktlen);
                iras.ira_ttl = ipha->ipha_ttl;

                /*
                 * Call one of:
                 *      ill_input_full_v4
                 *      ill_input_short_v4
                 * The former is used in unusual cases. See ill_set_inputfn().
                 */
                (*ill->ill_inputfn)(mp, ipha, &ipha->ipha_dst, &iras, &rtc);

                /* Any references to clean up? No hold on ira_ill */
                if (iras.ira_flags & (IRAF_IPSEC_SECURE|IRAF_SYSTEM_LABELED))
                        ira_cleanup(&iras, B_FALSE);

                if (iras.ira_target_sqp_mp != NULL) {
                        /* Better be called from ip_accept_tcp */
                        ASSERT(target_sqp != NULL);

                        /* Found one packet to accept */
                        mp = iras.ira_target_sqp_mp;
                        iras.ira_target_sqp_mp = NULL;
                        ASSERT(ip_recv_attr_is_mblk(mp));

                        if (atail != NULL)
                                atail->b_next = mp;
                        else
                                ahead = mp;
                        atail = mp;
                        acnt++;
                        mp = NULL;
                }
                /* mhip might point into 1st packet in the chain. */
                iras.ira_mhip = NULL;
        }
        /* Any remaining references to the route cache? */
        if (rtc.rtc_ire != NULL) {
                ASSERT(rtc.rtc_ipaddr != INADDR_ANY);
                ire_refrele(rtc.rtc_ire);
        }

        if (ahead != NULL) {
                /* Better be called from ip_accept_tcp */
                ASSERT(target_sqp != NULL);
                *last = atail;
                *cnt = acnt;
                return (ahead);
        }

        return (NULL);
}

/*
 * This input function is used when
 *  - is_system_labeled()
 *  - CGTP filtering
 *  - DHCP unicast before we have an IP address configured
 *  - there is an listener for IPPROTO_RSVP
 */
void
ill_input_full_v4(mblk_t *mp, void *iph_arg, void *nexthop_arg,
    ip_recv_attr_t *ira, rtc_t *rtc)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ipaddr_t        nexthop = *(ipaddr_t *)nexthop_arg;
        ill_t           *ill = ira->ira_ill;
        ip_stack_t      *ipst = ill->ill_ipst;
        int             cgtp_flt_pkt;

        ASSERT(ira->ira_tsl == NULL);

        /*
         * Attach any necessary label information to
         * this packet
         */
        if (is_system_labeled()) {
                ira->ira_flags |= IRAF_SYSTEM_LABELED;

                /*
                 * This updates ira_cred, ira_tsl and ira_free_flags based
                 * on the label.
                 */
                if (!tsol_get_pkt_label(mp, IPV4_VERSION, ira)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        freemsg(mp);
                        return;
                }
                /* Note that ira_tsl can be NULL here. */

                /* tsol_get_pkt_label sometimes does pullupmsg */
                ipha = (ipha_t *)mp->b_rptr;
        }

        /*
         * Invoke the CGTP (multirouting) filtering module to process
         * the incoming packet. Packets identified as duplicates
         * must be discarded. Filtering is active only if the
         * the ip_cgtp_filter ndd variable is non-zero.
         */
        cgtp_flt_pkt = CGTP_IP_PKT_NOT_CGTP;
        if (ipst->ips_ip_cgtp_filter &&
            ipst->ips_ip_cgtp_filter_ops != NULL) {
                netstackid_t stackid;

                stackid = ipst->ips_netstack->netstack_stackid;
                /*
                 * CGTP and IPMP are mutually exclusive so
                 * phyint_ifindex is fine here.
                 */
                cgtp_flt_pkt =
                    ipst->ips_ip_cgtp_filter_ops->cfo_filter(stackid,
                    ill->ill_phyint->phyint_ifindex, mp);
                if (cgtp_flt_pkt == CGTP_IP_PKT_DUPLICATE) {
                        ip_drop_input("CGTP_IP_PKT_DUPLICATE", mp, ill);
                        freemsg(mp);
                        return;
                }
        }

        /*
         * Brutal hack for DHCPv4 unicast: RFC2131 allows a DHCP
         * server to unicast DHCP packets to a DHCP client using the
         * IP address it is offering to the client.  This can be
         * disabled through the "broadcast bit", but not all DHCP
         * servers honor that bit.  Therefore, to interoperate with as
         * many DHCP servers as possible, the DHCP client allows the
         * server to unicast, but we treat those packets as broadcast
         * here.  Note that we don't rewrite the packet itself since
         * (a) that would mess up the checksums and (b) the DHCP
         * client conn is bound to INADDR_ANY so ip_fanout_udp() will
         * hand it the packet regardless.
         */
        if (ill->ill_dhcpinit != 0 &&
            ipha->ipha_version_and_hdr_length == IP_SIMPLE_HDR_VERSION &&
            ipha->ipha_protocol == IPPROTO_UDP) {
                udpha_t *udpha;

                ipha = ip_pullup(mp, sizeof (ipha_t) + sizeof (udpha_t), ira);
                if (ipha == NULL) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards - dhcp", mp, ill);
                        freemsg(mp);
                        return;
                }
                /* Reload since pullupmsg() can change b_rptr. */
                udpha = (udpha_t *)&ipha[1];

                if (ntohs(udpha->uha_dst_port) == IPPORT_BOOTPC) {
                        DTRACE_PROBE2(ip4__dhcpinit__pkt, ill_t *, ill,
                            mblk_t *, mp);
                        /*
                         * This assumes that we deliver to all conns for
                         * multicast and broadcast packets.
                         */
                        nexthop = INADDR_BROADCAST;
                        ira->ira_flags |= IRAF_DHCP_UNICAST;
                }
        }

        /*
         * If rsvpd is running, let RSVP daemon handle its processing
         * and forwarding of RSVP multicast/unicast packets.
         * If rsvpd is not running but mrouted is running, RSVP
         * multicast packets are forwarded as multicast traffic
         * and RSVP unicast packets are forwarded by unicast router.
         * If neither rsvpd nor mrouted is running, RSVP multicast
         * packets are not forwarded, but the unicast packets are
         * forwarded like unicast traffic.
         */
        if (ipha->ipha_protocol == IPPROTO_RSVP &&
            ipst->ips_ipcl_proto_fanout_v4[IPPROTO_RSVP].connf_head != NULL) {
                /* RSVP packet and rsvpd running. Treat as ours */
                ip2dbg(("ip_input: RSVP for us: 0x%x\n", ntohl(nexthop)));
                /*
                 * We use a multicast address to get the packet to
                 * ire_recv_multicast_v4. There will not be a membership
                 * check since we set IRAF_RSVP
                 */
                nexthop = htonl(INADDR_UNSPEC_GROUP);
                ira->ira_flags |= IRAF_RSVP;
        }

        ill_input_short_v4(mp, ipha, &nexthop, ira, rtc);
}

/*
 * This is the tail-end of the full receive side packet handling.
 * It can be used directly when the configuration is simple.
 */
void
ill_input_short_v4(mblk_t *mp, void *iph_arg, void *nexthop_arg,
    ip_recv_attr_t *ira, rtc_t *rtc)
{
        ire_t           *ire;
        uint_t          opt_len;
        ill_t           *ill = ira->ira_ill;
        ip_stack_t      *ipst = ill->ill_ipst;
        uint_t          pkt_len;
        ssize_t         len;
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ipaddr_t        nexthop = *(ipaddr_t *)nexthop_arg;
        ilb_stack_t     *ilbs = ipst->ips_netstack->netstack_ilb;
        uint_t          irr_flags;
#define rptr    ((uchar_t *)ipha)

        ASSERT(DB_TYPE(mp) == M_DATA);

        /*
         * The following test for loopback is faster than
         * IP_LOOPBACK_ADDR(), because it avoids any bitwise
         * operations.
         * Note that these addresses are always in network byte order
         */
        if (((*(uchar_t *)&ipha->ipha_dst) == IN_LOOPBACKNET) ||
            ((*(uchar_t *)&ipha->ipha_src) == IN_LOOPBACKNET)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInAddrErrors);
                ip_drop_input("ipIfStatsInAddrErrors", mp, ill);
                freemsg(mp);
                return;
        }

        len = mp->b_wptr - rptr;
        pkt_len = ira->ira_pktlen;

        /* multiple mblk or too short */
        len -= pkt_len;
        if (len != 0) {
                mp = ip_check_length(mp, rptr, len, pkt_len,
                    IP_SIMPLE_HDR_LENGTH, ira);
                if (mp == NULL)
                        return;
                ipha = (ipha_t *)mp->b_rptr;
        }

        DTRACE_IP7(receive, mblk_t *, mp, conn_t *, NULL, void_ip_t *,
            ipha, __dtrace_ipsr_ill_t *, ill, ipha_t *, ipha, ip6_t *, NULL,
            int, 0);

        /*
         * The event for packets being received from a 'physical'
         * interface is placed after validation of the source and/or
         * destination address as being local so that packets can be
         * redirected to loopback addresses using ipnat.
         */
        DTRACE_PROBE4(ip4__physical__in__start,
            ill_t *, ill, ill_t *, NULL,
            ipha_t *, ipha, mblk_t *, mp);

        if (HOOKS4_INTERESTED_PHYSICAL_IN(ipst)) {
                int     ll_multicast = 0;
                int     error;
                ipaddr_t orig_dst = ipha->ipha_dst;

                if (ira->ira_flags & IRAF_L2DST_MULTICAST)
                        ll_multicast = HPE_MULTICAST;
                else if (ira->ira_flags & IRAF_L2DST_BROADCAST)
                        ll_multicast = HPE_BROADCAST;

                FW_HOOKS(ipst->ips_ip4_physical_in_event,
                    ipst->ips_ipv4firewall_physical_in,
                    ill, NULL, ipha, mp, mp, ll_multicast, ipst, error);

                DTRACE_PROBE1(ip4__physical__in__end, mblk_t *, mp);

                if (mp == NULL)
                        return;
                /* The length could have changed */
                ipha = (ipha_t *)mp->b_rptr;
                ira->ira_pktlen = ntohs(ipha->ipha_length);
                pkt_len = ira->ira_pktlen;

                /*
                 * In case the destination changed we override any previous
                 * change to nexthop.
                 */
                if (orig_dst != ipha->ipha_dst)
                        nexthop = ipha->ipha_dst;
                if (nexthop == INADDR_ANY) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInAddrErrors);
                        ip_drop_input("ipIfStatsInAddrErrors", mp, ill);
                        freemsg(mp);
                        return;
                }
        }

        if (ipst->ips_ip4_observe.he_interested) {
                zoneid_t dzone;

                /*
                 * On the inbound path the src zone will be unknown as
                 * this packet has come from the wire.
                 */
                dzone = ip_get_zoneid_v4(nexthop, mp, ira, ALL_ZONES);
                ipobs_hook(mp, IPOBS_HOOK_INBOUND, ALL_ZONES, dzone, ill, ipst);
        }

        /*
         * If the packet originated from a same-machine sender or
         * there is a good HW IP header checksum, we clear the need
         * look at the IP header checksum.
         */
        if (((DB_CKSUMFLAGS(mp) & HCK_IPV4_HDRCKSUM) &&
            ILL_HCKSUM_CAPABLE(ill) && dohwcksum)) {
                /* Header checksum was ok. Clear the flag */
                DB_CKSUMFLAGS(mp) &= ~HCK_IPV4_HDRCKSUM;
                ira->ira_flags &= ~IRAF_VERIFY_IP_CKSUM;
        }

        /*
         * Here we check to see if we machine is setup as
         * L3 loadbalancer and if the incoming packet is for a VIP
         *
         * Check the following:
         * - there is at least a rule
         * - protocol of the packet is supported
         */
        if (ilb_has_rules(ilbs) && ILB_SUPP_L4(ipha->ipha_protocol)) {
                ipaddr_t        lb_dst;
                int             lb_ret;

                /* For convenience, we pull up the mblk. */
                if (mp->b_cont != NULL) {
                        if (pullupmsg(mp, -1) == 0) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                ip_drop_input("ipIfStatsInDiscards - pullupmsg",
                                    mp, ill);
                                freemsg(mp);
                                return;
                        }
                        ipha = (ipha_t *)mp->b_rptr;
                }

                /*
                 * We just drop all fragments going to any VIP, at
                 * least for now....
                 */
                if (ntohs(ipha->ipha_fragment_offset_and_flags) &
                    (IPH_MF | IPH_OFFSET)) {
                        if (!ilb_rule_match_vip_v4(ilbs, nexthop, NULL)) {
                                goto after_ilb;
                        }

                        ILB_KSTAT_UPDATE(ilbs, ip_frag_in, 1);
                        ILB_KSTAT_UPDATE(ilbs, ip_frag_dropped, 1);
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ILB fragment", mp, ill);
                        freemsg(mp);
                        return;
                }
                lb_ret = ilb_check_v4(ilbs, ill, mp, ipha, ipha->ipha_protocol,
                    (uint8_t *)ipha + IPH_HDR_LENGTH(ipha), &lb_dst);

                if (lb_ret == ILB_DROPPED) {
                        /* Is this the right counter to increase? */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ILB_DROPPED", mp, ill);
                        freemsg(mp);
                        return;
                }
                if (lb_ret == ILB_BALANCED) {
                        /* Set the dst to that of the chosen server */
                        nexthop = lb_dst;
                        DB_CKSUMFLAGS(mp) = 0;
                }
        }

after_ilb:
        opt_len = ipha->ipha_version_and_hdr_length - IP_SIMPLE_HDR_VERSION;
        ira->ira_ip_hdr_length = IP_SIMPLE_HDR_LENGTH;
        if (opt_len != 0) {
                int error = 0;

                ira->ira_ip_hdr_length += (opt_len << 2);
                ira->ira_flags |= IRAF_IPV4_OPTIONS;

                /* IP Options present!  Validate the length. */
                mp = ip_check_optlen(mp, ipha, opt_len, pkt_len, ira);
                if (mp == NULL)
                        return;

                /* Might have changed */
                ipha = (ipha_t *)mp->b_rptr;

                /* Verify IP header checksum before parsing the options */
                if ((ira->ira_flags & IRAF_VERIFY_IP_CKSUM) &&
                    ip_csum_hdr(ipha)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInCksumErrs);
                        ip_drop_input("ipIfStatsInCksumErrs", mp, ill);
                        freemsg(mp);
                        return;
                }
                ira->ira_flags &= ~IRAF_VERIFY_IP_CKSUM;

                /*
                 * Go off to ip_input_options which returns the next hop
                 * destination address, which may have been affected
                 * by source routing.
                 */
                IP_STAT(ipst, ip_opt);

                nexthop = ip_input_options(ipha, nexthop, mp, ira, &error);
                if (error != 0) {
                        /*
                         * An ICMP error has been sent and the packet has
                         * been dropped.
                         */
                        return;
                }
        }

        if (ill->ill_flags & ILLF_ROUTER)
                irr_flags = IRR_ALLOCATE;
        else
                irr_flags = IRR_NONE;

        /* Can not use route cache with TX since the labels can differ */
        if (ira->ira_flags & IRAF_SYSTEM_LABELED) {
                if (CLASSD(nexthop)) {
                        ire = ire_multicast(ill);
                } else {
                        /* Match destination and label */
                        ire = ire_route_recursive_v4(nexthop, 0, NULL,
                            ALL_ZONES, ira->ira_tsl, MATCH_IRE_SECATTR,
                            irr_flags, ira->ira_xmit_hint, ipst, NULL, NULL,
                            NULL);
                }
                /* Update the route cache so we do the ire_refrele */
                ASSERT(ire != NULL);
                if (rtc->rtc_ire != NULL)
                        ire_refrele(rtc->rtc_ire);
                rtc->rtc_ire = ire;
                rtc->rtc_ipaddr = nexthop;
        } else if (nexthop == rtc->rtc_ipaddr && rtc->rtc_ire != NULL) {
                /* Use the route cache */
                ire = rtc->rtc_ire;
        } else {
                /* Update the route cache */
                if (CLASSD(nexthop)) {
                        ire = ire_multicast(ill);
                } else {
                        /* Just match the destination */
                        ire = ire_route_recursive_dstonly_v4(nexthop, irr_flags,
                            ira->ira_xmit_hint, ipst);
                }
                ASSERT(ire != NULL);
                if (rtc->rtc_ire != NULL)
                        ire_refrele(rtc->rtc_ire);
                rtc->rtc_ire = ire;
                rtc->rtc_ipaddr = nexthop;
        }

        ire->ire_ib_pkt_count++;

        /*
         * Based on ire_type and ire_flags call one of:
         *      ire_recv_local_v4 - for IRE_LOCAL
         *      ire_recv_loopback_v4 - for IRE_LOOPBACK
         *      ire_recv_multirt_v4 - if RTF_MULTIRT
         *      ire_recv_noroute_v4 - if RTF_REJECT or RTF_BLACHOLE
         *      ire_recv_multicast_v4 - for IRE_MULTICAST
         *      ire_recv_broadcast_v4 - for IRE_BROADCAST
         *      ire_recv_noaccept_v4 - for ire_noaccept ones
         *      ire_recv_forward_v4 - for the rest.
         */
        (*ire->ire_recvfn)(ire, mp, ipha, ira);
}
#undef rptr

/*
 * ire_recvfn for IREs that need forwarding
 */
void
ire_recv_forward_v4(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ill_t           *ill = ira->ira_ill;
        ip_stack_t      *ipst = ill->ill_ipst;
        ill_t           *dst_ill;
        nce_t           *nce;
        ipaddr_t        src = ipha->ipha_src;
        uint32_t        added_tx_len;
        uint32_t        mtu, iremtu;

        if (ira->ira_flags & (IRAF_L2DST_MULTICAST|IRAF_L2DST_BROADCAST)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                ip_drop_input("l2 multicast not forwarded", mp, ill);
                freemsg(mp);
                return;
        }

        if (!(ill->ill_flags & ILLF_ROUTER) && !ip_source_routed(ipha, ipst)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                ip_drop_input("ipIfStatsForwProhibits", mp, ill);
                freemsg(mp);
                return;
        }

        /*
         * Either ire_nce_capable or ire_dep_parent would be set for the IRE
         * when it is found by ire_route_recursive, but that some other thread
         * could have changed the routes with the effect of clearing
         * ire_dep_parent. In that case we'd end up dropping the packet, or
         * finding a new nce below.
         * Get, allocate, or update the nce.
         * We get a refhold on ire_nce_cache as a result of this to avoid races
         * where ire_nce_cache is deleted.
         *
         * This ensures that we don't forward if the interface is down since
         * ipif_down removes all the nces.
         */
        mutex_enter(&ire->ire_lock);
        nce = ire->ire_nce_cache;
        if (nce == NULL) {
                /* Not yet set up - try to set one up */
                mutex_exit(&ire->ire_lock);
                (void) ire_revalidate_nce(ire);
                mutex_enter(&ire->ire_lock);
                nce = ire->ire_nce_cache;
                if (nce == NULL) {
                        mutex_exit(&ire->ire_lock);
                        /* The ire_dep_parent chain went bad, or no memory */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("No ire_dep_parent", mp, ill);
                        freemsg(mp);
                        return;
                }
        }
        nce_refhold(nce);
        mutex_exit(&ire->ire_lock);

        if (nce->nce_is_condemned) {
                nce_t *nce1;

                nce1 = ire_handle_condemned_nce(nce, ire, ipha, NULL, B_FALSE);
                nce_refrele(nce);
                if (nce1 == NULL) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("No nce", mp, ill);
                        freemsg(mp);
                        return;
                }
                nce = nce1;
        }
        dst_ill = nce->nce_ill;

        /*
         * Unless we are forwarding, drop the packet.
         * We have to let source routed packets through if they go out
         * the same interface i.e., they are 'ping -l' packets.
         */
        if (!(dst_ill->ill_flags & ILLF_ROUTER) &&
            !(ip_source_routed(ipha, ipst) && dst_ill == ill)) {
                if (ip_source_routed(ipha, ipst)) {
                        ip_drop_input("ICMP_SOURCE_ROUTE_FAILED", mp, ill);
                        icmp_unreachable(mp, ICMP_SOURCE_ROUTE_FAILED, ira);
                        nce_refrele(nce);
                        return;
                }
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                ip_drop_input("ipIfStatsForwProhibits", mp, ill);
                freemsg(mp);
                nce_refrele(nce);
                return;
        }

        if (ire->ire_zoneid != GLOBAL_ZONEID && ire->ire_zoneid != ALL_ZONES) {
                ipaddr_t        dst = ipha->ipha_dst;

                ire->ire_ib_pkt_count--;
                /*
                 * Should only use IREs that are visible from the
                 * global zone for forwarding.
                 * Take a source route into account the same way as ip_input
                 * did.
                 */
                if (ira->ira_flags & IRAF_IPV4_OPTIONS) {
                        int             error = 0;

                        dst = ip_input_options(ipha, dst, mp, ira, &error);
                        ASSERT(error == 0);     /* ip_input checked */
                }
                ire = ire_route_recursive_v4(dst, 0, NULL, GLOBAL_ZONEID,
                    ira->ira_tsl, MATCH_IRE_SECATTR,
                    (ill->ill_flags & ILLF_ROUTER) ? IRR_ALLOCATE : IRR_NONE,
                    ira->ira_xmit_hint, ipst, NULL, NULL, NULL);
                ire->ire_ib_pkt_count++;
                (*ire->ire_recvfn)(ire, mp, ipha, ira);
                ire_refrele(ire);
                nce_refrele(nce);
                return;
        }

        /*
         * ipIfStatsHCInForwDatagrams should only be increment if there
         * will be an attempt to forward the packet, which is why we
         * increment after the above condition has been checked.
         */
        BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInForwDatagrams);

        /* Initiate Read side IPPF processing */
        if (IPP_ENABLED(IPP_FWD_IN, ipst)) {
                /* ip_process translates an IS_UNDER_IPMP */
                mp = ip_process(IPP_FWD_IN, mp, ill, ill);
                if (mp == NULL) {
                        /* ip_drop_packet and MIB done */
                        ip2dbg(("ire_recv_forward_v4: pkt dropped/deferred "
                            "during IPPF processing\n"));
                        nce_refrele(nce);
                        return;
                }
        }

        DTRACE_PROBE4(ip4__forwarding__start,
            ill_t *, ill, ill_t *, dst_ill, ipha_t *, ipha, mblk_t *, mp);

        if (HOOKS4_INTERESTED_FORWARDING(ipst)) {
                int error;

                FW_HOOKS(ipst->ips_ip4_forwarding_event,
                    ipst->ips_ipv4firewall_forwarding,
                    ill, dst_ill, ipha, mp, mp, 0, ipst, error);

                DTRACE_PROBE1(ip4__forwarding__end, mblk_t *, mp);

                if (mp == NULL) {
                        nce_refrele(nce);
                        return;
                }
                /*
                 * Even if the destination was changed by the filter we use the
                 * forwarding decision that was made based on the address
                 * in ip_input.
                 */

                /* Might have changed */
                ipha = (ipha_t *)mp->b_rptr;
                ira->ira_pktlen = ntohs(ipha->ipha_length);
        }

        /* Packet is being forwarded. Turning off hwcksum flag. */
        DB_CKSUMFLAGS(mp) = 0;

        /*
         * Martian Address Filtering [RFC 1812, Section 5.3.7]
         * The loopback address check for both src and dst has already
         * been checked in ip_input
         * In the future one can envision adding RPF checks using number 3.
         * If we already checked the same source address we can skip this.
         */
        if (!(ira->ira_flags & IRAF_VERIFIED_SRC) ||
            src != ira->ira_verified_src) {
                switch (ipst->ips_src_check) {
                case 0:
                        break;
                case 2:
                        if (ip_type_v4(src, ipst) == IRE_BROADCAST) {
                                BUMP_MIB(ill->ill_ip_mib,
                                    ipIfStatsForwProhibits);
                                BUMP_MIB(ill->ill_ip_mib,
                                    ipIfStatsInAddrErrors);
                                ip_drop_input("ipIfStatsInAddrErrors", mp, ill);
                                freemsg(mp);
                                nce_refrele(nce);
                                return;
                        }
                        /* FALLTHRU */

                case 1:
                        if (CLASSD(src)) {
                                BUMP_MIB(ill->ill_ip_mib,
                                    ipIfStatsForwProhibits);
                                BUMP_MIB(ill->ill_ip_mib,
                                    ipIfStatsInAddrErrors);
                                ip_drop_input("ipIfStatsInAddrErrors", mp, ill);
                                freemsg(mp);
                                nce_refrele(nce);
                                return;
                        }
                        break;
                }
                /* Remember for next packet */
                ira->ira_flags |= IRAF_VERIFIED_SRC;
                ira->ira_verified_src = src;
        }

        /*
         * Check if packet is going out the same link on which it arrived.
         * Means we might need to send a redirect.
         */
        if (IS_ON_SAME_LAN(dst_ill, ill) && ipst->ips_ip_g_send_redirects) {
                ip_send_potential_redirect_v4(mp, ipha, ire, ira);
        }

        added_tx_len = 0;
        if (ira->ira_flags & IRAF_SYSTEM_LABELED) {
                mblk_t          *mp1;
                uint32_t        old_pkt_len = ira->ira_pktlen;

                /* Verify IP header checksum before adding/removing options */
                if ((ira->ira_flags & IRAF_VERIFY_IP_CKSUM) &&
                    ip_csum_hdr(ipha)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInCksumErrs);
                        ip_drop_input("ipIfStatsInCksumErrs", mp, ill);
                        freemsg(mp);
                        nce_refrele(nce);
                        return;
                }
                ira->ira_flags &= ~IRAF_VERIFY_IP_CKSUM;

                /*
                 * Check if it can be forwarded and add/remove
                 * CIPSO options as needed.
                 */
                if ((mp1 = tsol_ip_forward(ire, mp, ira)) == NULL) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                        ip_drop_input("tsol_ip_forward", mp, ill);
                        freemsg(mp);
                        nce_refrele(nce);
                        return;
                }
                /*
                 * Size may have changed. Remember amount added in case
                 * IP needs to send an ICMP too big.
                 */
                mp = mp1;
                ipha = (ipha_t *)mp->b_rptr;
                ira->ira_pktlen = ntohs(ipha->ipha_length);
                ira->ira_ip_hdr_length = IPH_HDR_LENGTH(ipha);
                if (ira->ira_pktlen > old_pkt_len)
                        added_tx_len = ira->ira_pktlen - old_pkt_len;

                /* Options can have been added or removed */
                if (ira->ira_ip_hdr_length != IP_SIMPLE_HDR_LENGTH)
                        ira->ira_flags |= IRAF_IPV4_OPTIONS;
                else
                        ira->ira_flags &= ~IRAF_IPV4_OPTIONS;
        }

        mtu = dst_ill->ill_mtu;
        if ((iremtu = ire->ire_metrics.iulp_mtu) != 0 && iremtu < mtu)
                mtu = iremtu;
        ip_forward_xmit_v4(nce, ill, mp, ipha, ira, mtu, added_tx_len);
        nce_refrele(nce);
}

/*
 * Used for sending out unicast and multicast packets that are
 * forwarded.
 */
void
ip_forward_xmit_v4(nce_t *nce, ill_t *ill, mblk_t *mp, ipha_t *ipha,
    ip_recv_attr_t *ira, uint32_t mtu, uint32_t added_tx_len)
{
        ill_t           *dst_ill = nce->nce_ill;
        uint32_t        pkt_len;
        uint32_t        sum;
        iaflags_t       iraflags = ira->ira_flags;
        ip_stack_t      *ipst = ill->ill_ipst;
        iaflags_t       ixaflags;

        if (ipha->ipha_ttl <= 1) {
                /* Perhaps the checksum was bad */
                if ((iraflags & IRAF_VERIFY_IP_CKSUM) && ip_csum_hdr(ipha)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInCksumErrs);
                        ip_drop_input("ipIfStatsInCksumErrs", mp, ill);
                        freemsg(mp);
                        return;
                }
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                ip_drop_input("ICMP_TTL_EXCEEDED", mp, ill);
                icmp_time_exceeded(mp, ICMP_TTL_EXCEEDED, ira);
                return;
        }

        /*
         * Count the forward as a hop and update the checksum
         * accordingly.
         */
        ipha->ipha_ttl--;
        sum = (int)ipha->ipha_hdr_checksum + IP_HDR_CSUM_TTL_ADJUST;
        ipha->ipha_hdr_checksum = (uint16_t)(sum + (sum >> 16));

        /* Check if there are options to update */
        if (iraflags & IRAF_IPV4_OPTIONS) {
                ASSERT(ipha->ipha_version_and_hdr_length !=
                    IP_SIMPLE_HDR_VERSION);
                ASSERT(!(iraflags & IRAF_VERIFY_IP_CKSUM));

                if (!ip_forward_options(mp, ipha, dst_ill, ira)) {
                        /* ipIfStatsForwProhibits and ip_drop_input done */
                        return;
                }

                ipha->ipha_hdr_checksum = 0;
                ipha->ipha_hdr_checksum = ip_csum_hdr(ipha);
        }

        /* Initiate Write side IPPF processing before any fragmentation */
        if (IPP_ENABLED(IPP_FWD_OUT, ipst)) {
                /* ip_process translates an IS_UNDER_IPMP */
                mp = ip_process(IPP_FWD_OUT, mp, dst_ill, dst_ill);
                if (mp == NULL) {
                        /* ip_drop_packet and MIB done */
                        ip2dbg(("ire_recv_forward_v4: pkt dropped/deferred" \
                            " during IPPF processing\n"));
                        return;
                }
        }

        pkt_len = ira->ira_pktlen;

        BUMP_MIB(dst_ill->ill_ip_mib, ipIfStatsHCOutForwDatagrams);

        ixaflags = IXAF_IS_IPV4 | IXAF_NO_DEV_FLOW_CTL;

        if (pkt_len > mtu) {
                /*
                 * It needs fragging on its way out.  If we haven't
                 * verified the header checksum yet we do it now since
                 * are going to put a surely good checksum in the
                 * outgoing header, we have to make sure that it
                 * was good coming in.
                 */
                if ((iraflags & IRAF_VERIFY_IP_CKSUM) && ip_csum_hdr(ipha)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInCksumErrs);
                        ip_drop_input("ipIfStatsInCksumErrs", mp, ill);
                        freemsg(mp);
                        return;
                }
                if (ipha->ipha_fragment_offset_and_flags & IPH_DF_HTONS) {
                        BUMP_MIB(dst_ill->ill_ip_mib, ipIfStatsOutFragFails);
                        ip_drop_output("ipIfStatsOutFragFails", mp, dst_ill);
                        if (iraflags & IRAF_SYSTEM_LABELED) {
                                /*
                                 * Remove any CIPSO option added by
                                 * tsol_ip_forward, and make sure we report
                                 * a path MTU so that there
                                 * is room to add such a CIPSO option for future
                                 * packets.
                                 */
                                mtu = tsol_pmtu_adjust(mp, mtu, added_tx_len,
                                    AF_INET);
                        }

                        icmp_frag_needed(mp, mtu, ira);
                        return;
                }

                (void) ip_fragment_v4(mp, nce, ixaflags, pkt_len, mtu,
                    ira->ira_xmit_hint, GLOBAL_ZONEID, 0, ip_xmit, NULL);
                return;
        }

        ASSERT(pkt_len == ntohs(((ipha_t *)mp->b_rptr)->ipha_length));
        if (iraflags & IRAF_LOOPBACK_COPY) {
                /*
                 * IXAF_NO_LOOP_ZONEID is not set hence 7th arg
                 * is don't care
                 */
                (void) ip_postfrag_loopcheck(mp, nce,
                    ixaflags | IXAF_LOOPBACK_COPY,
                    pkt_len, ira->ira_xmit_hint, GLOBAL_ZONEID, 0, NULL);
        } else {
                (void) ip_xmit(mp, nce, ixaflags, pkt_len, ira->ira_xmit_hint,
                    GLOBAL_ZONEID, 0, NULL);
        }
}

/*
 * ire_recvfn for RTF_REJECT and RTF_BLACKHOLE routes, including IRE_NOROUTE,
 * which is what ire_route_recursive returns when there is no matching ire.
 * Send ICMP unreachable unless blackhole.
 */
void
ire_recv_noroute_v4(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ill_t           *ill = ira->ira_ill;
        ip_stack_t      *ipst = ill->ill_ipst;

        /* Would we have forwarded this packet if we had a route? */
        if (ira->ira_flags & (IRAF_L2DST_MULTICAST|IRAF_L2DST_BROADCAST)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                ip_drop_input("l2 multicast not forwarded", mp, ill);
                freemsg(mp);
                return;
        }

        if (!(ill->ill_flags & ILLF_ROUTER)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                ip_drop_input("ipIfStatsForwProhibits", mp, ill);
                freemsg(mp);
                return;
        }
        /*
         * If we had a route this could have been forwarded. Count as such.
         *
         * ipIfStatsHCInForwDatagrams should only be increment if there
         * will be an attempt to forward the packet, which is why we
         * increment after the above condition has been checked.
         */
        BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInForwDatagrams);

        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInNoRoutes);

        ip_rts_change(RTM_MISS, ipha->ipha_dst, 0, 0, 0, 0, 0, 0, RTA_DST,
            ipst);

        if (ire->ire_flags & RTF_BLACKHOLE) {
                ip_drop_input("ipIfStatsInNoRoutes RTF_BLACKHOLE", mp, ill);
                freemsg(mp);
        } else {
                ip_drop_input("ipIfStatsInNoRoutes RTF_REJECT", mp, ill);

                if (ip_source_routed(ipha, ipst)) {
                        icmp_unreachable(mp, ICMP_SOURCE_ROUTE_FAILED, ira);
                } else {
                        icmp_unreachable(mp, ICMP_HOST_UNREACHABLE, ira);
                }
        }
}

/*
 * ire_recvfn for IRE_LOCALs marked with ire_noaccept. Such IREs are used for
 * VRRP when in noaccept mode.
 * We silently drop the packet. ARP handles packets even if noaccept is set.
 */
/* ARGSUSED */
void
ire_recv_noaccept_v4(ire_t *ire, mblk_t *mp, void *iph_arg,
    ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_ill;

        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
        ip_drop_input("ipIfStatsInDiscards - noaccept", mp, ill);
        freemsg(mp);
}

/*
 * ire_recvfn for IRE_BROADCAST.
 */
void
ire_recv_broadcast_v4(ire_t *ire, mblk_t *mp, void *iph_arg,
    ip_recv_attr_t *ira)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ill_t           *ill = ira->ira_ill;
        ill_t           *dst_ill = ire->ire_ill;
        ip_stack_t      *ipst = ill->ill_ipst;
        ire_t           *alt_ire;
        nce_t           *nce;
        ipaddr_t        ipha_dst;

        BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInBcastPkts);

        /* Tag for higher-level protocols */
        ira->ira_flags |= IRAF_BROADCAST;

        /*
         * Whether local or directed broadcast forwarding: don't allow
         * for TCP.
         */
        if (ipha->ipha_protocol == IPPROTO_TCP) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                ip_drop_input("ipIfStatsInDiscards", mp, ill);
                freemsg(mp);
                return;
        }

        /*
         * So that we don't end up with dups, only one ill an IPMP group is
         * nominated to receive broadcast traffic.
         * If we have no cast_ill we are liberal and accept everything.
         */
        if (IS_UNDER_IPMP(ill)) {
                /* For an under ill_grp can change under lock */
                rw_enter(&ipst->ips_ill_g_lock, RW_READER);
                if (!ill->ill_nom_cast && ill->ill_grp != NULL &&
                    ill->ill_grp->ig_cast_ill != NULL) {
                        rw_exit(&ipst->ips_ill_g_lock);
                        /* No MIB since this is normal operation */
                        ip_drop_input("not nom_cast", mp, ill);
                        freemsg(mp);
                        return;
                }
                rw_exit(&ipst->ips_ill_g_lock);

                ira->ira_ruifindex = ill_get_upper_ifindex(ill);
        }

        /*
         * After reassembly and IPsec we will need to duplicate the
         * broadcast packet for all matching zones on the ill.
         */
        ira->ira_zoneid = ALL_ZONES;

        /*
         * Check for directed broadcast i.e. ire->ire_ill is different than
         * the incoming ill.
         * The same broadcast address can be assigned to multiple interfaces
         * so have to check explicitly for that case by looking up the alt_ire
         */
        if (dst_ill == ill && !(ire->ire_flags & RTF_MULTIRT)) {
                /* Reassemble on the ill on which the packet arrived */
                ip_input_local_v4(ire, mp, ipha, ira);
                /* Restore */
                ira->ira_ruifindex = ill->ill_phyint->phyint_ifindex;
                return;
        }

        /* Is there an IRE_BROADCAST on the incoming ill? */
        ipha_dst = ((ira->ira_flags & IRAF_DHCP_UNICAST) ? INADDR_BROADCAST :
            ipha->ipha_dst);
        alt_ire = ire_ftable_lookup_v4(ipha_dst, 0, 0, IRE_BROADCAST, ill,
            ALL_ZONES, ira->ira_tsl,
            MATCH_IRE_TYPE|MATCH_IRE_ILL|MATCH_IRE_SECATTR, 0, ipst, NULL);
        if (alt_ire != NULL) {
                /* Not a directed broadcast */
                /*
                 * In the special case of multirouted broadcast
                 * packets, we unconditionally need to "gateway"
                 * them to the appropriate interface here so that reassembly
                 * works. We know that the IRE_BROADCAST on cgtp0 doesn't
                 * have RTF_MULTIRT set so we look for such an IRE in the
                 * bucket.
                 */
                if (alt_ire->ire_flags & RTF_MULTIRT) {
                        irb_t           *irb;
                        ire_t           *ire1;

                        irb = ire->ire_bucket;
                        irb_refhold(irb);
                        for (ire1 = irb->irb_ire; ire1 != NULL;
                            ire1 = ire1->ire_next) {
                                if (IRE_IS_CONDEMNED(ire1))
                                        continue;
                                if (!(ire1->ire_type & IRE_BROADCAST) ||
                                    (ire1->ire_flags & RTF_MULTIRT))
                                        continue;
                                ill = ire1->ire_ill;
                                ill_refhold(ill);
                                break;
                        }
                        irb_refrele(irb);
                        if (ire1 != NULL) {
                                ill_t *orig_ill = ira->ira_ill;

                                ire_refrele(alt_ire);
                                /* Reassemble on the new ill */
                                ira->ira_ill = ill;
                                ip_input_local_v4(ire, mp, ipha, ira);
                                ill_refrele(ill);
                                /* Restore */
                                ira->ira_ill = orig_ill;
                                ira->ira_ruifindex =
                                    orig_ill->ill_phyint->phyint_ifindex;
                                return;
                        }
                }
                ire_refrele(alt_ire);
                /* Reassemble on the ill on which the packet arrived */
                ip_input_local_v4(ire, mp, ipha, ira);
                goto done;
        }

        /*
         * This is a directed broadcast
         *
         * If directed broadcast is allowed, then forward the packet out
         * the destination interface with IXAF_LOOPBACK_COPY set. That will
         * result in ip_input() receiving a copy of the packet on the
         * appropriate ill. (We could optimize this to avoid the extra trip
         * via ip_input(), but since directed broadcasts are normally disabled
         * it doesn't make sense to optimize it.)
         */
        if (!ipst->ips_ip_g_forward_directed_bcast ||
            (ira->ira_flags & (IRAF_L2DST_MULTICAST|IRAF_L2DST_BROADCAST))) {
                ip_drop_input("directed broadcast not allowed", mp, ill);
                freemsg(mp);
                goto done;
        }
        if ((ira->ira_flags & IRAF_VERIFY_IP_CKSUM) && ip_csum_hdr(ipha)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInCksumErrs);
                ip_drop_input("ipIfStatsInCksumErrs", mp, ill);
                freemsg(mp);
                goto done;
        }

        /*
         * Clear the indication that this may have hardware
         * checksum as we are not using it for forwarding.
         */
        DB_CKSUMFLAGS(mp) = 0;

        /*
         * Adjust ttl to 2 (1+1 - the forward engine will decrement it by one.
         */
        ipha->ipha_ttl = ipst->ips_ip_broadcast_ttl + 1;
        ipha->ipha_hdr_checksum = 0;
        ipha->ipha_hdr_checksum = ip_csum_hdr(ipha);

        /*
         * We use ip_forward_xmit to do any fragmentation.
         * and loopback copy on the outbound interface.
         *
         * Make it so that IXAF_LOOPBACK_COPY to be set on transmit side.
         */
        ira->ira_flags |= IRAF_LOOPBACK_COPY;

        nce = arp_nce_init(dst_ill, ipha->ipha_dst, IRE_BROADCAST);
        if (nce == NULL) {
                BUMP_MIB(dst_ill->ill_ip_mib, ipIfStatsOutDiscards);
                ip_drop_output("No nce", mp, dst_ill);
                freemsg(mp);
                goto done;
        }

        ip_forward_xmit_v4(nce, ill, mp, ipha, ira, dst_ill->ill_mc_mtu, 0);
        nce_refrele(nce);
done:
        /* Restore */
        ira->ira_ruifindex = ill->ill_phyint->phyint_ifindex;
}

/*
 * ire_recvfn for IRE_MULTICAST.
 */
void
ire_recv_multicast_v4(ire_t *ire, mblk_t *mp, void *iph_arg,
    ip_recv_attr_t *ira)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ill_t           *ill = ira->ira_ill;
        ip_stack_t      *ipst = ill->ill_ipst;

        ASSERT(ire->ire_ill == ira->ira_ill);

        BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInMcastPkts);
        UPDATE_MIB(ill->ill_ip_mib, ipIfStatsHCInMcastOctets, ira->ira_pktlen);

        /* RSVP hook */
        if (ira->ira_flags & IRAF_RSVP)
                goto forus;

        /* Tag for higher-level protocols */
        ira->ira_flags |= IRAF_MULTICAST;

        /*
         * So that we don't end up with dups, only one ill an IPMP group is
         * nominated to receive multicast traffic.
         * If we have no cast_ill we are liberal and accept everything.
         */
        if (IS_UNDER_IPMP(ill)) {
                ip_stack_t      *ipst = ill->ill_ipst;

                /* For an under ill_grp can change under lock */
                rw_enter(&ipst->ips_ill_g_lock, RW_READER);
                if (!ill->ill_nom_cast && ill->ill_grp != NULL &&
                    ill->ill_grp->ig_cast_ill != NULL) {
                        rw_exit(&ipst->ips_ill_g_lock);
                        ip_drop_input("not on cast ill", mp, ill);
                        freemsg(mp);
                        return;
                }
                rw_exit(&ipst->ips_ill_g_lock);
                /*
                 * We switch to the upper ill so that mrouter and hasmembers
                 * can operate on upper here and in ip_input_multicast.
                 */
                ill = ipmp_ill_hold_ipmp_ill(ill);
                if (ill != NULL) {
                        ASSERT(ill != ira->ira_ill);
                        ASSERT(ire->ire_ill == ira->ira_ill);
                        ira->ira_ill = ill;
                        ira->ira_ruifindex = ill->ill_phyint->phyint_ifindex;
                } else {
                        ill = ira->ira_ill;
                }
        }

        /*
         * Check if we are a multicast router - send ip_mforward a copy of
         * the packet.
         * Due to mroute_decap tunnels we consider forwarding packets even if
         * mrouted has not joined the allmulti group on this interface.
         */
        if (ipst->ips_ip_g_mrouter) {
                int retval;

                /*
                 * Clear the indication that this may have hardware
                 * checksum as we are not using it for forwarding.
                 */
                DB_CKSUMFLAGS(mp) = 0;

                /*
                 * ip_mforward helps us make these distinctions: If received
                 * on tunnel and not IGMP, then drop.
                 * If IGMP packet, then don't check membership
                 * If received on a phyint and IGMP or PIM, then
                 * don't check membership
                 */
                retval = ip_mforward(mp, ira);
                /* ip_mforward updates mib variables if needed */

                switch (retval) {
                case 0:
                        /*
                         * pkt is okay and arrived on phyint.
                         *
                         * If we are running as a multicast router
                         * we need to see all IGMP and/or PIM packets.
                         */
                        if ((ipha->ipha_protocol == IPPROTO_IGMP) ||
                            (ipha->ipha_protocol == IPPROTO_PIM)) {
                                goto forus;
                        }
                        break;
                case -1:
                        /* pkt is mal-formed, toss it */
                        freemsg(mp);
                        goto done;
                case 1:
                        /*
                         * pkt is okay and arrived on a tunnel
                         *
                         * If we are running a multicast router
                         * we need to see all igmp packets.
                         */
                        if (ipha->ipha_protocol == IPPROTO_IGMP) {
                                goto forus;
                        }
                        ip_drop_input("Multicast on tunnel ignored", mp, ill);
                        freemsg(mp);
                        goto done;
                }
        }

        /*
         * Check if we have members on this ill. This is not necessary for
         * correctness because even if the NIC/GLD had a leaky filter, we
         * filter before passing to each conn_t.
         */
        if (!ill_hasmembers_v4(ill, ipha->ipha_dst)) {
                /*
                 * Nobody interested
                 *
                 * This might just be caused by the fact that
                 * multiple IP Multicast addresses map to the same
                 * link layer multicast - no need to increment counter!
                 */
                ip_drop_input("Multicast with no members", mp, ill);
                freemsg(mp);
                goto done;
        }
forus:
        ip2dbg(("ire_recv_multicast_v4: multicast for us: 0x%x\n",
            ntohl(ipha->ipha_dst)));

        /*
         * After reassembly and IPsec we will need to duplicate the
         * multicast packet for all matching zones on the ill.
         */
        ira->ira_zoneid = ALL_ZONES;

        /* Reassemble on the ill on which the packet arrived */
        ip_input_local_v4(ire, mp, ipha, ira);
done:
        if (ill != ire->ire_ill) {
                ill_refrele(ill);
                ira->ira_ill = ire->ire_ill;
                ira->ira_ruifindex = ira->ira_ill->ill_phyint->phyint_ifindex;
        }
}

/*
 * ire_recvfn for IRE_OFFLINK with RTF_MULTIRT.
 * Drop packets since we don't forward out multirt routes.
 */
/* ARGSUSED */
void
ire_recv_multirt_v4(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_ill;

        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInNoRoutes);
        ip_drop_input("Not forwarding out MULTIRT", mp, ill);
        freemsg(mp);
}

/*
 * ire_recvfn for IRE_LOOPBACK. This is only used when a FW_HOOK
 * has rewritten the packet to have a loopback destination address (We
 * filter out packet with a loopback destination from arriving over the wire).
 * We don't know what zone to use, thus we always use the GLOBAL_ZONEID.
 */
void
ire_recv_loopback_v4(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ill_t           *ill = ira->ira_ill;
        ill_t           *ire_ill = ire->ire_ill;

        ira->ira_zoneid = GLOBAL_ZONEID;

        /* Switch to the lo0 ill for further processing  */
        if (ire_ill != ill) {
                /*
                 * Update ira_ill to be the ILL on which the IP address
                 * is hosted.
                 * No need to hold the ill since we have a hold on the ire
                 */
                ASSERT(ira->ira_ill == ira->ira_rill);
                ira->ira_ill = ire_ill;

                ip_input_local_v4(ire, mp, ipha, ira);

                /* Restore */
                ASSERT(ira->ira_ill == ire_ill);
                ira->ira_ill = ill;
                return;

        }
        ip_input_local_v4(ire, mp, ipha, ira);
}

/*
 * ire_recvfn for IRE_LOCAL.
 */
void
ire_recv_local_v4(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
{
        ipha_t          *ipha = (ipha_t *)iph_arg;
        ill_t           *ill = ira->ira_ill;
        ill_t           *ire_ill = ire->ire_ill;

        /* Make a note for DAD that this address is in use */
        ire->ire_last_used_time = LBOLT_FASTPATH;

        /* Only target the IRE_LOCAL with the right zoneid. */
        ira->ira_zoneid = ire->ire_zoneid;

        /*
         * If the packet arrived on the wrong ill, we check that
         * this is ok.
         * If it is, then we ensure that we do the reassembly on
         * the ill on which the address is hosted. We keep ira_rill as
         * the one on which the packet arrived, so that IP_PKTINFO and
         * friends can report this.
         */
        if (ire_ill != ill) {
                ire_t *new_ire;

                new_ire = ip_check_multihome(&ipha->ipha_dst, ire, ill);
                if (new_ire == NULL) {
                        /* Drop packet */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsForwProhibits);
                        ip_drop_input("ipIfStatsInForwProhibits", mp, ill);
                        freemsg(mp);
                        return;
                }
                /*
                 * Update ira_ill to be the ILL on which the IP address
                 * is hosted. No need to hold the ill since we have a
                 * hold on the ire. Note that we do the switch even if
                 * new_ire == ire (for IPMP, ire would be the one corresponding
                 * to the IPMP ill).
                 */
                ASSERT(ira->ira_ill == ira->ira_rill);
                ira->ira_ill = new_ire->ire_ill;

                /* ira_ruifindex tracks the upper for ira_rill */
                if (IS_UNDER_IPMP(ill))
                        ira->ira_ruifindex = ill_get_upper_ifindex(ill);

                ip_input_local_v4(new_ire, mp, ipha, ira);

                /* Restore */
                ASSERT(ira->ira_ill == new_ire->ire_ill);
                ira->ira_ill = ill;
                ira->ira_ruifindex = ill->ill_phyint->phyint_ifindex;

                if (new_ire != ire)
                        ire_refrele(new_ire);
                return;
        }

        ip_input_local_v4(ire, mp, ipha, ira);
}

/*
 * Common function for packets arriving for the host. Handles
 * checksum verification, reassembly checks, etc.
 */
static void
ip_input_local_v4(ire_t *ire, mblk_t *mp, ipha_t *ipha, ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_ill;
        iaflags_t       iraflags = ira->ira_flags;

        /*
         * Verify IP header checksum. If the packet was AH or ESP then
         * this flag has already been cleared. Likewise if the packet
         * had a hardware checksum.
         */
        if ((iraflags & IRAF_VERIFY_IP_CKSUM) && ip_csum_hdr(ipha)) {
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInCksumErrs);
                ip_drop_input("ipIfStatsInCksumErrs", mp, ill);
                freemsg(mp);
                return;
        }

        if (iraflags & IRAF_IPV4_OPTIONS) {
                if (!ip_input_local_options(mp, ipha, ira)) {
                        /* Error has been sent and mp consumed */
                        return;
                }
                /*
                 * Some old hardware does partial checksum by including the
                 * whole IP header, so the partial checksum value might have
                 * become invalid if any option in the packet have been
                 * updated. Always clear partial checksum flag here.
                 */
                DB_CKSUMFLAGS(mp) &= ~HCK_PARTIALCKSUM;
        }

        /*
         * Is packet part of fragmented IP packet?
         * We compare against defined values in network byte order
         */
        if (ipha->ipha_fragment_offset_and_flags &
            (IPH_MF_HTONS | IPH_OFFSET_HTONS)) {
                /*
                 * Make sure we have ira_l2src before we loose the original
                 * mblk
                 */
                if (!(ira->ira_flags & IRAF_L2SRC_SET))
                        ip_setl2src(mp, ira, ira->ira_rill);

                mp = ip_input_fragment(mp, ipha, ira);
                if (mp == NULL)
                        return;
                /* Completed reassembly */
                ipha = (ipha_t *)mp->b_rptr;
        }

        /*
         * For broadcast and multicast we need some extra work before
         * we call ip_fanout_v4(), since in the case of shared-IP zones
         * we need to pretend that a packet arrived for each zoneid.
         */
        if (iraflags & IRAF_MULTIBROADCAST) {
                if (iraflags & IRAF_BROADCAST)
                        ip_input_broadcast_v4(ire, mp, ipha, ira);
                else
                        ip_input_multicast_v4(ire, mp, ipha, ira);
                return;
        }
        ip_fanout_v4(mp, ipha, ira);
}


/*
 * Handle multiple zones which match the same broadcast address
 * and ill by delivering a packet to each of them.
 * Walk the bucket and look for different ire_zoneid but otherwise
 * the same IRE (same ill/addr/mask/type).
 * Note that ire_add() tracks IREs that are identical in all
 * fields (addr/mask/type/gw/ill/zoneid) within a single IRE by
 * increasing ire_identical_cnt. Thus we don't need to be concerned
 * about those.
 */
static void
ip_input_broadcast_v4(ire_t *ire, mblk_t *mp, ipha_t *ipha, ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_ill;
        ip_stack_t      *ipst = ill->ill_ipst;
        netstack_t      *ns = ipst->ips_netstack;
        irb_t           *irb;
        ire_t           *ire1;
        mblk_t          *mp1;
        ipha_t          *ipha1;
        uint_t          ira_pktlen = ira->ira_pktlen;
        uint16_t        ira_ip_hdr_length = ira->ira_ip_hdr_length;

        irb = ire->ire_bucket;

        /*
         * If we don't have more than one shared-IP zone, or if
         * there can't be more than one IRE_BROADCAST for this
         * IP address, then just set the zoneid and proceed.
         */
        if (ns->netstack_numzones == 1 || irb->irb_ire_cnt == 1) {
                ira->ira_zoneid = ire->ire_zoneid;

                ip_fanout_v4(mp, ipha, ira);
                return;
        }
        irb_refhold(irb);
        for (ire1 = irb->irb_ire; ire1 != NULL; ire1 = ire1->ire_next) {
                /* We do the main IRE after the end of the loop */
                if (ire1 == ire)
                        continue;

                /*
                 * Only IREs for the same IP address should be in the same
                 * bucket.
                 * But could have IRE_HOSTs in the case of CGTP.
                 */
                ASSERT(ire1->ire_addr == ire->ire_addr);
                if (!(ire1->ire_type & IRE_BROADCAST))
                        continue;

                if (IRE_IS_CONDEMNED(ire1))
                        continue;

                mp1 = copymsg(mp);
                if (mp1 == NULL) {
                        /* Failed to deliver to one zone */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        continue;
                }
                ira->ira_zoneid = ire1->ire_zoneid;
                ipha1 = (ipha_t *)mp1->b_rptr;
                ip_fanout_v4(mp1, ipha1, ira);
                /*
                 * IPsec might have modified ira_pktlen and ira_ip_hdr_length
                 * so we restore them for a potential next iteration
                 */
                ira->ira_pktlen = ira_pktlen;
                ira->ira_ip_hdr_length = ira_ip_hdr_length;
        }
        irb_refrele(irb);
        /* Do the main ire */
        ira->ira_zoneid = ire->ire_zoneid;
        ip_fanout_v4(mp, ipha, ira);
}

/*
 * Handle multiple zones which want to receive the same multicast packets
 * on this ill by delivering a packet to each of them.
 *
 * Note that for packets delivered to transports we could instead do this
 * as part of the fanout code, but since we need to handle icmp_inbound
 * it is simpler to have multicast work the same as broadcast.
 *
 * The ip_fanout matching for multicast matches based on ilm independent of
 * zoneid since the zoneid restriction is applied when joining a multicast
 * group.
 */
/* ARGSUSED */
static void
ip_input_multicast_v4(ire_t *ire, mblk_t *mp, ipha_t *ipha, ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_ill;
        iaflags_t       iraflags = ira->ira_flags;
        ip_stack_t      *ipst = ill->ill_ipst;
        netstack_t      *ns = ipst->ips_netstack;
        zoneid_t        zoneid;
        mblk_t          *mp1;
        ipha_t          *ipha1;
        uint_t          ira_pktlen = ira->ira_pktlen;
        uint16_t        ira_ip_hdr_length = ira->ira_ip_hdr_length;

        /* ire_recv_multicast has switched to the upper ill for IPMP */
        ASSERT(!IS_UNDER_IPMP(ill));

        /*
         * If we don't have more than one shared-IP zone, or if
         * there are no members in anything but the global zone,
         * then just set the zoneid and proceed.
         */
        if (ns->netstack_numzones == 1 ||
            !ill_hasmembers_otherzones_v4(ill, ipha->ipha_dst,
            GLOBAL_ZONEID)) {
                ira->ira_zoneid = GLOBAL_ZONEID;

                /* If sender didn't want this zone to receive it, drop */
                if ((iraflags & IRAF_NO_LOOP_ZONEID_SET) &&
                    ira->ira_no_loop_zoneid == ira->ira_zoneid) {
                        ip_drop_input("Multicast but wrong zoneid", mp, ill);
                        freemsg(mp);
                        return;
                }
                ip_fanout_v4(mp, ipha, ira);
                return;
        }

        /*
         * Here we loop over all zoneids that have members in the group
         * and deliver a packet to ip_fanout for each zoneid.
         *
         * First find any members in the lowest numeric zoneid by looking for
         * first zoneid larger than -1 (ALL_ZONES).
         * We terminate the loop when we receive -1 (ALL_ZONES).
         */
        zoneid = ill_hasmembers_nextzone_v4(ill, ipha->ipha_dst, ALL_ZONES);
        for (; zoneid != ALL_ZONES;
            zoneid = ill_hasmembers_nextzone_v4(ill, ipha->ipha_dst, zoneid)) {
                /*
                 * Avoid an extra copymsg/freemsg by skipping global zone here
                 * and doing that at the end.
                 */
                if (zoneid == GLOBAL_ZONEID)
                        continue;

                ira->ira_zoneid = zoneid;

                /* If sender didn't want this zone to receive it, skip */
                if ((iraflags & IRAF_NO_LOOP_ZONEID_SET) &&
                    ira->ira_no_loop_zoneid == ira->ira_zoneid)
                        continue;

                mp1 = copymsg(mp);
                if (mp1 == NULL) {
                        /* Failed to deliver to one zone */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        continue;
                }
                ipha1 = (ipha_t *)mp1->b_rptr;
                ip_fanout_v4(mp1, ipha1, ira);
                /*
                 * IPsec might have modified ira_pktlen and ira_ip_hdr_length
                 * so we restore them for a potential next iteration
                 */
                ira->ira_pktlen = ira_pktlen;
                ira->ira_ip_hdr_length = ira_ip_hdr_length;
        }

        /* Do the main ire */
        ira->ira_zoneid = GLOBAL_ZONEID;
        /* If sender didn't want this zone to receive it, drop */
        if ((iraflags & IRAF_NO_LOOP_ZONEID_SET) &&
            ira->ira_no_loop_zoneid == ira->ira_zoneid) {
                ip_drop_input("Multicast but wrong zoneid", mp, ill);
                freemsg(mp);
        } else {
                ip_fanout_v4(mp, ipha, ira);
        }
}


/*
 * Determine the zoneid and IRAF_TX_* flags if trusted extensions
 * is in use. Updates ira_zoneid and ira_flags as a result.
 */
static void
ip_fanout_tx_v4(mblk_t *mp, ipha_t *ipha, uint8_t protocol,
    uint_t ip_hdr_length, ip_recv_attr_t *ira)
{
        uint16_t        *up;
        uint16_t        lport;
        zoneid_t        zoneid;

        ASSERT(ira->ira_flags & IRAF_SYSTEM_LABELED);

        /*
         * If the packet is unlabeled we might allow read-down
         * for MAC_EXEMPT. Below we clear this if it is a multi-level
         * port (MLP).
         * Note that ira_tsl can be NULL here.
         */
        if (ira->ira_tsl != NULL && ira->ira_tsl->tsl_flags & TSLF_UNLABELED)
                ira->ira_flags |= IRAF_TX_MAC_EXEMPTABLE;

        if (ira->ira_zoneid != ALL_ZONES)
                return;

        ira->ira_flags |= IRAF_TX_SHARED_ADDR;

        up = (uint16_t *)((uchar_t *)ipha + ip_hdr_length);
        switch (protocol) {
        case IPPROTO_TCP:
        case IPPROTO_SCTP:
        case IPPROTO_UDP:
                /* Caller ensures this */
                ASSERT(((uchar_t *)ipha) + ip_hdr_length +4 <= mp->b_wptr);

                /*
                 * Only these transports support MLP.
                 * We know their destination port numbers is in
                 * the same place in the header.
                 */
                lport = up[1];

                /*
                 * No need to handle exclusive-stack zones
                 * since ALL_ZONES only applies to the shared IP instance.
                 */
                zoneid = tsol_mlp_findzone(protocol, lport);
                /*
                 * If no shared MLP is found, tsol_mlp_findzone returns
                 * ALL_ZONES.  In that case, we assume it's SLP, and
                 * search for the zone based on the packet label.
                 *
                 * If there is such a zone, we prefer to find a
                 * connection in it.  Otherwise, we look for a
                 * MAC-exempt connection in any zone whose label
                 * dominates the default label on the packet.
                 */
                if (zoneid == ALL_ZONES)
                        zoneid = tsol_attr_to_zoneid(ira);
                else
                        ira->ira_flags &= ~IRAF_TX_MAC_EXEMPTABLE;
                break;
        default:
                /* Handle shared address for other protocols */
                zoneid = tsol_attr_to_zoneid(ira);
                break;
        }
        ira->ira_zoneid = zoneid;
}

/*
 * Increment checksum failure statistics
 */
static void
ip_input_cksum_err_v4(uint8_t protocol, uint16_t hck_flags, ill_t *ill)
{
        ip_stack_t      *ipst = ill->ill_ipst;

        switch (protocol) {
        case IPPROTO_TCP:
                BUMP_MIB(ill->ill_ip_mib, tcpIfStatsInErrs);

                if (hck_flags & HCK_FULLCKSUM)
                        IP_STAT(ipst, ip_tcp_in_full_hw_cksum_err);
                else if (hck_flags & HCK_PARTIALCKSUM)
                        IP_STAT(ipst, ip_tcp_in_part_hw_cksum_err);
                else
                        IP_STAT(ipst, ip_tcp_in_sw_cksum_err);
                break;
        case IPPROTO_UDP:
                BUMP_MIB(ill->ill_ip_mib, udpIfStatsInCksumErrs);
                if (hck_flags & HCK_FULLCKSUM)
                        IP_STAT(ipst, ip_udp_in_full_hw_cksum_err);
                else if (hck_flags & HCK_PARTIALCKSUM)
                        IP_STAT(ipst, ip_udp_in_part_hw_cksum_err);
                else
                        IP_STAT(ipst, ip_udp_in_sw_cksum_err);
                break;
        case IPPROTO_ICMP:
                BUMP_MIB(&ipst->ips_icmp_mib, icmpInCksumErrs);
                break;
        default:
                ASSERT(0);
                break;
        }
}

/* Calculate the IPv4 pseudo-header checksum */
uint32_t
ip_input_cksum_pseudo_v4(ipha_t *ipha, ip_recv_attr_t *ira)
{
        uint_t          ulp_len;
        uint32_t        cksum;
        uint8_t         protocol = ira->ira_protocol;
        uint16_t        ip_hdr_length = ira->ira_ip_hdr_length;

#define iphs    ((uint16_t *)ipha)

        switch (protocol) {
        case IPPROTO_TCP:
                ulp_len = ira->ira_pktlen - ip_hdr_length;

                /* Protocol and length */
                cksum = htons(ulp_len) + IP_TCP_CSUM_COMP;
                /* IP addresses */
                cksum += iphs[6] + iphs[7] + iphs[8] + iphs[9];
                break;

        case IPPROTO_UDP: {
                udpha_t         *udpha;

                udpha = (udpha_t  *)((uchar_t *)ipha + ip_hdr_length);

                /* Protocol and length */
                cksum = udpha->uha_length + IP_UDP_CSUM_COMP;
                /* IP addresses */
                cksum += iphs[6] + iphs[7] + iphs[8] + iphs[9];
                break;
        }

        default:
                cksum = 0;
                break;
        }
#undef  iphs
        return (cksum);
}


/*
 * Software verification of the ULP checksums.
 * Returns B_TRUE if ok.
 * Increments statistics of failed.
 */
static boolean_t
ip_input_sw_cksum_v4(mblk_t *mp, ipha_t *ipha, ip_recv_attr_t *ira)
{
        ip_stack_t      *ipst = ira->ira_ill->ill_ipst;
        uint32_t        cksum;
        uint8_t         protocol = ira->ira_protocol;
        uint16_t        ip_hdr_length = ira->ira_ip_hdr_length;

        IP_STAT(ipst, ip_in_sw_cksum);

        ASSERT(protocol == IPPROTO_TCP || protocol == IPPROTO_UDP);

        cksum = ip_input_cksum_pseudo_v4(ipha, ira);
        cksum = IP_CSUM(mp, ip_hdr_length, cksum);
        if (cksum == 0)
                return (B_TRUE);

        ip_input_cksum_err_v4(protocol, 0, ira->ira_ill);
        return (B_FALSE);
}

/*
 * Verify the ULP checksums.
 * Returns B_TRUE if ok, or if the ULP doesn't have a well-defined checksum
 * algorithm.
 * Increments statistics if failed.
 */
static boolean_t
ip_input_cksum_v4(iaflags_t iraflags, mblk_t *mp, ipha_t *ipha,
    ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_rill;
        uint16_t        hck_flags;
        uint32_t        cksum;
        mblk_t          *mp1;
        int32_t         len;
        uint8_t         protocol = ira->ira_protocol;
        uint16_t        ip_hdr_length = ira->ira_ip_hdr_length;


        switch (protocol) {
        case IPPROTO_TCP:
                break;

        case IPPROTO_UDP: {
                udpha_t         *udpha;

                udpha = (udpha_t  *)((uchar_t *)ipha + ip_hdr_length);
                if (udpha->uha_checksum == 0) {
                        /* Packet doesn't have a UDP checksum */
                        return (B_TRUE);
                }
                break;
        }
        case IPPROTO_SCTP: {
                sctp_hdr_t      *sctph;
                uint32_t        pktsum;

                sctph = (sctp_hdr_t *)((uchar_t *)ipha + ip_hdr_length);
#ifdef  DEBUG
                if (skip_sctp_cksum)
                        return (B_TRUE);
#endif
                pktsum = sctph->sh_chksum;
                sctph->sh_chksum = 0;
                cksum = sctp_cksum(mp, ip_hdr_length);
                sctph->sh_chksum = pktsum;
                if (cksum == pktsum)
                        return (B_TRUE);

                /*
                 * Defer until later whether a bad checksum is ok
                 * in order to allow RAW sockets to use Adler checksum
                 * with SCTP.
                 */
                ira->ira_flags |= IRAF_SCTP_CSUM_ERR;
                return (B_TRUE);
        }

        default:
                /* No ULP checksum to verify. */
                return (B_TRUE);
        }

        /*
         * Revert to software checksum calculation if the interface
         * isn't capable of checksum offload.
         * We clear DB_CKSUMFLAGS when going through IPsec in ip_fanout.
         * Note: IRAF_NO_HW_CKSUM is not currently used.
         */
        ASSERT(!IS_IPMP(ill));
        if ((iraflags & IRAF_NO_HW_CKSUM) || !ILL_HCKSUM_CAPABLE(ill) ||
            !dohwcksum) {
                return (ip_input_sw_cksum_v4(mp, ipha, ira));
        }

        hck_flags = DB_CKSUMFLAGS(mp);

        /*
         * We apply this for all ULP protocols. Does the HW know to
         * not set the flags for SCTP and other protocols.
         */
        if (hck_flags & HCK_FULLCKSUM_OK) {
                /*
                 * Hardware has already verified the checksum.
                 */
                return (B_TRUE);
        }

        if (hck_flags & HCK_FULLCKSUM) {
                /*
                 * Full checksum has been computed by the hardware
                 * and has been attached.  If the driver wants us to
                 * verify the correctness of the attached value, in
                 * order to protect against faulty hardware, compare
                 * it against -0 (0xFFFF) to see if it's valid.
                 */
                cksum = DB_CKSUM16(mp);
                if (cksum == 0xFFFF)
                        return (B_TRUE);
                ip_input_cksum_err_v4(protocol, hck_flags, ira->ira_ill);
                return (B_FALSE);
        }

        mp1 = mp->b_cont;
        if ((hck_flags & HCK_PARTIALCKSUM) &&
            (mp1 == NULL || mp1->b_cont == NULL) &&
            ip_hdr_length >= DB_CKSUMSTART(mp) &&
            ((len = ip_hdr_length - DB_CKSUMSTART(mp)) & 1) == 0) {
                uint32_t        adj;
                uchar_t         *cksum_start;

                cksum = ip_input_cksum_pseudo_v4(ipha, ira);

                cksum_start = ((uchar_t *)ipha + DB_CKSUMSTART(mp));

                /*
                 * Partial checksum has been calculated by hardware
                 * and attached to the packet; in addition, any
                 * prepended extraneous data is even byte aligned,
                 * and there are at most two mblks associated with
                 * the packet.  If any such data exists, we adjust
                 * the checksum; also take care any postpended data.
                 */
                IP_ADJCKSUM_PARTIAL(cksum_start, mp, mp1, len, adj);
                /*
                 * One's complement subtract extraneous checksum
                 */
                cksum += DB_CKSUM16(mp);
                if (adj >= cksum)
                        cksum = ~(adj - cksum) & 0xFFFF;
                else
                        cksum -= adj;
                cksum = (cksum & 0xFFFF) + ((int)cksum >> 16);
                cksum = (cksum & 0xFFFF) + ((int)cksum >> 16);
                if (!(~cksum & 0xFFFF))
                        return (B_TRUE);

                ip_input_cksum_err_v4(protocol, hck_flags, ira->ira_ill);
                return (B_FALSE);
        }
        return (ip_input_sw_cksum_v4(mp, ipha, ira));
}


/*
 * Handle fanout of received packets.
 * Unicast packets that are looped back (from ire_send_local_v4) and packets
 * from the wire are differentiated by checking IRAF_VERIFY_ULP_CKSUM.
 *
 * IPQoS Notes
 * Before sending it to the client, invoke IPPF processing. Policy processing
 * takes place only if the callout_position, IPP_LOCAL_IN, is enabled.
 */
void
ip_fanout_v4(mblk_t *mp, ipha_t *ipha, ip_recv_attr_t *ira)
{
        ill_t           *ill = ira->ira_ill;
        iaflags_t       iraflags = ira->ira_flags;
        ip_stack_t      *ipst = ill->ill_ipst;
        uint8_t         protocol = ipha->ipha_protocol;
        conn_t          *connp;
#define rptr    ((uchar_t *)ipha)
        uint_t          ip_hdr_length;
        uint_t          min_ulp_header_length;
        int             offset;
        ssize_t         len;
        netstack_t      *ns = ipst->ips_netstack;
        ipsec_stack_t   *ipss = ns->netstack_ipsec;
        ill_t           *rill = ira->ira_rill;

        ASSERT(ira->ira_pktlen == ntohs(ipha->ipha_length));

        ip_hdr_length = ira->ira_ip_hdr_length;
        ira->ira_protocol = protocol;

        /*
         * Time for IPP once we've done reassembly and IPsec.
         * We skip this for loopback packets since we don't do IPQoS
         * on loopback.
         */
        if (IPP_ENABLED(IPP_LOCAL_IN, ipst) &&
            !(iraflags & IRAF_LOOPBACK) &&
            (protocol != IPPROTO_ESP && protocol != IPPROTO_AH)) {
                /*
                 * Use the interface on which the packet arrived - not where
                 * the IP address is hosted.
                 */
                /* ip_process translates an IS_UNDER_IPMP */
                mp = ip_process(IPP_LOCAL_IN, mp, rill, ill);
                if (mp == NULL) {
                        /* ip_drop_packet and MIB done */
                        return;
                }
        }

        /* Determine the minimum required size of the upper-layer header */
        /* Need to do this for at least the set of ULPs that TX handles. */
        switch (protocol) {
        case IPPROTO_TCP:
                min_ulp_header_length = TCP_MIN_HEADER_LENGTH;
                break;
        case IPPROTO_SCTP:
                min_ulp_header_length = SCTP_COMMON_HDR_LENGTH;
                break;
        case IPPROTO_UDP:
                min_ulp_header_length = UDPH_SIZE;
                break;
        case IPPROTO_ICMP:
                min_ulp_header_length = ICMPH_SIZE;
                break;
        default:
                min_ulp_header_length = 0;
                break;
        }
        /* Make sure we have the min ULP header length */
        len = mp->b_wptr - rptr;
        if (len < ip_hdr_length + min_ulp_header_length) {
                if (ira->ira_pktlen < ip_hdr_length + min_ulp_header_length) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInTruncatedPkts);
                        ip_drop_input("ipIfStatsInTruncatedPkts", mp, ill);
                        freemsg(mp);
                        return;
                }
                IP_STAT(ipst, ip_recv_pullup);
                ipha = ip_pullup(mp, ip_hdr_length + min_ulp_header_length,
                    ira);
                if (ipha == NULL)
                        goto discard;
                len = mp->b_wptr - rptr;
        }

        /*
         * If trusted extensions then determine the zoneid and TX specific
         * ira_flags.
         */
        if (iraflags & IRAF_SYSTEM_LABELED) {
                /* This can update ira->ira_flags and ira->ira_zoneid */
                ip_fanout_tx_v4(mp, ipha, protocol, ip_hdr_length, ira);
                iraflags = ira->ira_flags;
        }


        /* Verify ULP checksum. Handles TCP, UDP, and SCTP */
        if (iraflags & IRAF_VERIFY_ULP_CKSUM) {
                if (!ip_input_cksum_v4(iraflags, mp, ipha, ira)) {
                        /* Bad checksum. Stats are already incremented */
                        ip_drop_input("Bad ULP checksum", mp, ill);
                        freemsg(mp);
                        return;
                }
                /* IRAF_SCTP_CSUM_ERR could have been set */
                iraflags = ira->ira_flags;
        }
        switch (protocol) {
        case IPPROTO_TCP:
                /* For TCP, discard broadcast and multicast packets. */
                if (iraflags & IRAF_MULTIBROADCAST)
                        goto discard;

                /* First mblk contains IP+TCP headers per above check */
                ASSERT(len >= ip_hdr_length + TCP_MIN_HEADER_LENGTH);

                /* TCP options present? */
                offset = ((uchar_t *)ipha)[ip_hdr_length + 12] >> 4;
                if (offset != 5) {
                        if (offset < 5)
                                goto discard;

                        /*
                         * There must be TCP options.
                         * Make sure we can grab them.
                         */
                        offset <<= 2;
                        offset += ip_hdr_length;
                        if (len < offset) {
                                if (ira->ira_pktlen < offset) {
                                        BUMP_MIB(ill->ill_ip_mib,
                                            ipIfStatsInTruncatedPkts);
                                        ip_drop_input(
                                            "ipIfStatsInTruncatedPkts",
                                            mp, ill);
                                        freemsg(mp);
                                        return;
                                }
                                IP_STAT(ipst, ip_recv_pullup);
                                ipha = ip_pullup(mp, offset, ira);
                                if (ipha == NULL)
                                        goto discard;
                                len = mp->b_wptr - rptr;
                        }
                }

                /*
                 * Pass up a squeue hint to tcp.
                 * If ira_sqp is already set (this is loopback) we leave it
                 * alone.
                 */
                if (ira->ira_sqp == NULL) {
                        ira->ira_sqp = ip_squeue_get(ira->ira_ring);
                }

                /* Look for AF_INET or AF_INET6 that matches */
                connp = ipcl_classify_v4(mp, IPPROTO_TCP, ip_hdr_length,
                    ira, ipst);
                if (connp == NULL) {
                        /* Send the TH_RST */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                        tcp_xmit_listeners_reset(mp, ira, ipst, NULL);
                        return;
                }
                if (connp->conn_min_ttl != 0 &&
                    connp->conn_min_ttl > ira->ira_ttl) {
                        CONN_DEC_REF(connp);
                        goto discard;
                }
                if (CONN_INBOUND_POLICY_PRESENT(connp, ipss) ||
                    (iraflags & IRAF_IPSEC_SECURE)) {
                        mp = ipsec_check_inbound_policy(mp, connp,
                            ipha, NULL, ira);
                        if (mp == NULL) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                /* Note that mp is NULL */
                                ip_drop_input("ipIfStatsInDiscards", mp, ill);
                                CONN_DEC_REF(connp);
                                return;
                        }
                }
                /* Found a client; up it goes */
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                ira->ira_ill = ira->ira_rill = NULL;
                if (!IPCL_IS_TCP(connp)) {
                        /* Not TCP; must be SOCK_RAW, IPPROTO_TCP */
                        (connp->conn_recv)(connp, mp, NULL, ira);
                        CONN_DEC_REF(connp);
                        ira->ira_ill = ill;
                        ira->ira_rill = rill;
                        return;
                }

                /*
                 * We do different processing whether called from
                 * ip_accept_tcp and we match the target, don't match
                 * the target, and when we are called by ip_input.
                 */
                if (iraflags & IRAF_TARGET_SQP) {
                        if (ira->ira_target_sqp == connp->conn_sqp) {
                                mblk_t  *attrmp;

                                attrmp = ip_recv_attr_to_mblk(ira);
                                if (attrmp == NULL) {
                                        BUMP_MIB(ill->ill_ip_mib,
                                            ipIfStatsInDiscards);
                                        ip_drop_input("ipIfStatsInDiscards",
                                            mp, ill);
                                        freemsg(mp);
                                        CONN_DEC_REF(connp);
                                } else {
                                        SET_SQUEUE(attrmp, connp->conn_recv,
                                            connp);
                                        attrmp->b_cont = mp;
                                        ASSERT(ira->ira_target_sqp_mp == NULL);
                                        ira->ira_target_sqp_mp = attrmp;
                                        /*
                                         * Conn ref release when drained from
                                         * the squeue.
                                         */
                                }
                        } else {
                                SQUEUE_ENTER_ONE(connp->conn_sqp, mp,
                                    connp->conn_recv, connp, ira, SQ_FILL,
                                    SQTAG_IP_TCP_INPUT);
                        }
                } else {
                        SQUEUE_ENTER_ONE(connp->conn_sqp, mp, connp->conn_recv,
                            connp, ira, ip_squeue_flag, SQTAG_IP_TCP_INPUT);
                }
                ira->ira_ill = ill;
                ira->ira_rill = rill;
                return;

        case IPPROTO_SCTP: {
                sctp_hdr_t      *sctph;
                in6_addr_t      map_src, map_dst;
                uint32_t        ports;  /* Source and destination ports */
                sctp_stack_t    *sctps = ipst->ips_netstack->netstack_sctp;

                /* For SCTP, discard broadcast and multicast packets. */
                if (iraflags & IRAF_MULTIBROADCAST)
                        goto discard;

                /*
                 * Since there is no SCTP h/w cksum support yet, just
                 * clear the flag.
                 */
                DB_CKSUMFLAGS(mp) = 0;

                /* Length ensured above */
                ASSERT(MBLKL(mp) >= ip_hdr_length + SCTP_COMMON_HDR_LENGTH);
                sctph = (sctp_hdr_t *)(rptr + ip_hdr_length);

                /* get the ports */
                ports = *(uint32_t *)&sctph->sh_sport;

                IN6_IPADDR_TO_V4MAPPED(ipha->ipha_dst, &map_dst);
                IN6_IPADDR_TO_V4MAPPED(ipha->ipha_src, &map_src);
                if (iraflags & IRAF_SCTP_CSUM_ERR) {
                        /*
                         * No potential sctp checksum errors go to the Sun
                         * sctp stack however they might be Adler-32 summed
                         * packets a userland stack bound to a raw IP socket
                         * could reasonably use. Note though that Adler-32 is
                         * a long deprecated algorithm and customer sctp
                         * networks should eventually migrate to CRC-32 at
                         * which time this facility should be removed.
                         */
                        ip_fanout_sctp_raw(mp, ipha, NULL, ports, ira);
                        return;
                }
                connp = sctp_fanout(&map_src, &map_dst, ports, ira, mp,
                    sctps, sctph);
                if (connp == NULL) {
                        /* Check for raw socket or OOTB handling */
                        ip_fanout_sctp_raw(mp, ipha, NULL, ports, ira);
                        return;
                }
                if (connp->conn_incoming_ifindex != 0 &&
                    connp->conn_incoming_ifindex != ira->ira_ruifindex) {
                        CONN_DEC_REF(connp);
                        /* Check for raw socket or OOTB handling */
                        ip_fanout_sctp_raw(mp, ipha, NULL, ports, ira);
                        return;
                }

                /* Found a client; up it goes */
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                sctp_input(connp, ipha, NULL, mp, ira);
                /* sctp_input does a rele of the sctp_t */
                return;
        }

        case IPPROTO_UDP:
                /* First mblk contains IP+UDP headers as checked above */
                ASSERT(MBLKL(mp) >= ip_hdr_length + UDPH_SIZE);

                if (iraflags & IRAF_MULTIBROADCAST) {
                        uint16_t *up;   /* Pointer to ports in ULP header */

                        up = (uint16_t *)((uchar_t *)ipha + ip_hdr_length);
                        ip_fanout_udp_multi_v4(mp, ipha, up[1], up[0], ira);
                        return;
                }

                /* Look for AF_INET or AF_INET6 that matches */
                connp = ipcl_classify_v4(mp, IPPROTO_UDP, ip_hdr_length,
                    ira, ipst);
                if (connp == NULL) {
                        if (ipst->ips_ipcl_proto_fanout_v4[IPPROTO_UDP].
                            connf_head != NULL) {
                                ASSERT(ira->ira_protocol == IPPROTO_UDP);
                                ip_fanout_proto_v4(mp, ipha, ira);
                        } else {
                                ip_fanout_send_icmp_v4(mp,
                                    ICMP_DEST_UNREACHABLE,
                                    ICMP_PORT_UNREACHABLE, ira);
                        }
                        return;

                }
                if (connp->conn_min_ttl != 0 &&
                    connp->conn_min_ttl > ira->ira_ttl) {
                        CONN_DEC_REF(connp);
                        goto discard;
                }
                if (IPCL_IS_NONSTR(connp) ? connp->conn_flow_cntrld :
                    !canputnext(connp->conn_rq)) {
                        CONN_DEC_REF(connp);
                        BUMP_MIB(ill->ill_ip_mib, udpIfStatsInOverflows);
                        ip_drop_input("udpIfStatsInOverflows", mp, ill);
                        freemsg(mp);
                        return;
                }
                if (CONN_INBOUND_POLICY_PRESENT(connp, ipss) ||
                    (iraflags & IRAF_IPSEC_SECURE)) {
                        mp = ipsec_check_inbound_policy(mp, connp,
                            ipha, NULL, ira);
                        if (mp == NULL) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                /* Note that mp is NULL */
                                ip_drop_input("ipIfStatsInDiscards", mp, ill);
                                CONN_DEC_REF(connp);
                                return;
                        }
                }
                /*
                 * Remove 0-spi if it's 0, or move everything behind
                 * the UDP header over it and forward to ESP via
                 * ip_fanout_v4().
                 */
                if (connp->conn_udp->udp_nat_t_endpoint) {
                        if (iraflags & IRAF_IPSEC_SECURE) {
                                ip_drop_packet(mp, B_TRUE, ira->ira_ill,
                                    DROPPER(ipss, ipds_esp_nat_t_ipsec),
                                    &ipss->ipsec_dropper);
                                CONN_DEC_REF(connp);
                                return;
                        }

                        mp = zero_spi_check(mp, ira);
                        if (mp == NULL) {
                                /*
                                 * Packet was consumed - probably sent to
                                 * ip_fanout_v4.
                                 */
                                CONN_DEC_REF(connp);
                                return;
                        }
                        /* Else continue like a normal UDP packet. */
                        ipha = (ipha_t *)mp->b_rptr;
                        protocol = ipha->ipha_protocol;
                        ira->ira_protocol = protocol;
                }
                /* Found a client; up it goes */
                IP_STAT(ipst, ip_udp_fannorm);
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                ira->ira_ill = ira->ira_rill = NULL;
                (connp->conn_recv)(connp, mp, NULL, ira);
                CONN_DEC_REF(connp);
                ira->ira_ill = ill;
                ira->ira_rill = rill;
                return;
        default:
                break;
        }

        /*
         * Clear hardware checksumming flag as it is currently only
         * used by TCP and UDP.
         */
        DB_CKSUMFLAGS(mp) = 0;

        switch (protocol) {
        case IPPROTO_ICMP:
                /*
                 * We need to accomodate icmp messages coming in clear
                 * until we get everything secure from the wire. If
                 * icmp_accept_clear_messages is zero we check with
                 * the global policy and act accordingly. If it is
                 * non-zero, we accept the message without any checks.
                 * But *this does not mean* that this will be delivered
                 * to RAW socket clients. By accepting we might send
                 * replies back, change our MTU value etc.,
                 * but delivery to the ULP/clients depends on their
                 * policy dispositions.
                 */
                if (ipst->ips_icmp_accept_clear_messages == 0) {
                        mp = ipsec_check_global_policy(mp, NULL,
                            ipha, NULL, ira, ns);
                        if (mp == NULL)
                                return;
                }

                /*
                 * On a labeled system, we have to check whether the zone
                 * itself is permitted to receive raw traffic.
                 */
                if (ira->ira_flags & IRAF_SYSTEM_LABELED) {
                        if (!tsol_can_accept_raw(mp, ira, B_FALSE)) {
                                BUMP_MIB(&ipst->ips_icmp_mib, icmpInErrors);
                                ip_drop_input("tsol_can_accept_raw", mp, ill);
                                freemsg(mp);
                                return;
                        }
                }

                /*
                 * ICMP header checksum, including checksum field,
                 * should be zero.
                 */
                if (IP_CSUM(mp, ip_hdr_length, 0)) {
                        BUMP_MIB(&ipst->ips_icmp_mib, icmpInCksumErrs);
                        ip_drop_input("icmpInCksumErrs", mp, ill);
                        freemsg(mp);
                        return;
                }
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                mp = icmp_inbound_v4(mp, ira);
                if (mp == NULL) {
                        /* No need to pass to RAW sockets */
                        return;
                }
                break;

        case IPPROTO_IGMP:
                /*
                 * If we are not willing to accept IGMP packets in clear,
                 * then check with global policy.
                 */
                if (ipst->ips_igmp_accept_clear_messages == 0) {
                        mp = ipsec_check_global_policy(mp, NULL,
                            ipha, NULL, ira, ns);
                        if (mp == NULL)
                                return;
                }
                if ((ira->ira_flags & IRAF_SYSTEM_LABELED) &&
                    !tsol_can_accept_raw(mp, ira, B_TRUE)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        freemsg(mp);
                        return;
                }
                /*
                 * Validate checksum
                 */
                if (IP_CSUM(mp, ip_hdr_length, 0)) {
                        ++ipst->ips_igmpstat.igps_rcv_badsum;
                        ip_drop_input("igps_rcv_badsum", mp, ill);
                        freemsg(mp);
                        return;
                }

                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                mp = igmp_input(mp, ira);
                if (mp == NULL) {
                        /* Bad packet - discarded by igmp_input */
                        return;
                }
                break;
        case IPPROTO_PIM:
                /*
                 * If we are not willing to accept PIM packets in clear,
                 * then check with global policy.
                 */
                if (ipst->ips_pim_accept_clear_messages == 0) {
                        mp = ipsec_check_global_policy(mp, NULL,
                            ipha, NULL, ira, ns);
                        if (mp == NULL)
                                return;
                }
                if ((ira->ira_flags & IRAF_SYSTEM_LABELED) &&
                    !tsol_can_accept_raw(mp, ira, B_TRUE)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        freemsg(mp);
                        return;
                }
                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);

                /* Checksum is verified in pim_input */
                mp = pim_input(mp, ira);
                if (mp == NULL) {
                        /* Bad packet - discarded by pim_input */
                        return;
                }
                break;
        case IPPROTO_AH:
        case IPPROTO_ESP: {
                /*
                 * Fast path for AH/ESP.
                 */
                netstack_t *ns = ipst->ips_netstack;
                ipsec_stack_t *ipss = ns->netstack_ipsec;

                IP_STAT(ipst, ipsec_proto_ahesp);

                if (!ipsec_loaded(ipss)) {
                        ip_proto_not_sup(mp, ira);
                        return;
                }

                BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                /* select inbound SA and have IPsec process the pkt */
                if (protocol == IPPROTO_ESP) {
                        esph_t *esph;
                        boolean_t esp_in_udp_sa;
                        boolean_t esp_in_udp_packet;

                        mp = ipsec_inbound_esp_sa(mp, ira, &esph);
                        if (mp == NULL)
                                return;

                        ASSERT(esph != NULL);
                        ASSERT(ira->ira_flags & IRAF_IPSEC_SECURE);
                        ASSERT(ira->ira_ipsec_esp_sa != NULL);
                        ASSERT(ira->ira_ipsec_esp_sa->ipsa_input_func != NULL);

                        esp_in_udp_sa = ((ira->ira_ipsec_esp_sa->ipsa_flags &
                            IPSA_F_NATT) != 0);
                        esp_in_udp_packet =
                            (ira->ira_flags & IRAF_ESP_UDP_PORTS) != 0;

                        /*
                         * The following is a fancy, but quick, way of saying:
                         * ESP-in-UDP SA and Raw ESP packet --> drop
                         *    OR
                         * ESP SA and ESP-in-UDP packet --> drop
                         */
                        if (esp_in_udp_sa != esp_in_udp_packet) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                ip_drop_packet(mp, B_TRUE, ira->ira_ill,
                                    DROPPER(ipss, ipds_esp_no_sa),
                                    &ipss->ipsec_dropper);
                                return;
                        }
                        mp = ira->ira_ipsec_esp_sa->ipsa_input_func(mp, esph,
                            ira);
                } else {
                        ah_t *ah;

                        mp = ipsec_inbound_ah_sa(mp, ira, &ah);
                        if (mp == NULL)
                                return;

                        ASSERT(ah != NULL);
                        ASSERT(ira->ira_flags & IRAF_IPSEC_SECURE);
                        ASSERT(ira->ira_ipsec_ah_sa != NULL);
                        ASSERT(ira->ira_ipsec_ah_sa->ipsa_input_func != NULL);
                        mp = ira->ira_ipsec_ah_sa->ipsa_input_func(mp, ah,
                            ira);
                }

                if (mp == NULL) {
                        /*
                         * Either it failed or is pending. In the former case
                         * ipIfStatsInDiscards was increased.
                         */
                        return;
                }
                /* we're done with IPsec processing, send it up */
                ip_input_post_ipsec(mp, ira);
                return;
        }
        case IPPROTO_ENCAP: {
                ipha_t          *inner_ipha;

                /*
                 * Handle self-encapsulated packets (IP-in-IP where
                 * the inner addresses == the outer addresses).
                 */
                if ((uchar_t *)ipha + ip_hdr_length + sizeof (ipha_t) >
                    mp->b_wptr) {
                        if (ira->ira_pktlen <
                            ip_hdr_length + sizeof (ipha_t)) {
                                BUMP_MIB(ill->ill_ip_mib,
                                    ipIfStatsInTruncatedPkts);
                                ip_drop_input("ipIfStatsInTruncatedPkts",
                                    mp, ill);
                                freemsg(mp);
                                return;
                        }
                        ipha = ip_pullup(mp, (uchar_t *)ipha + ip_hdr_length +
                            sizeof (ipha_t) - mp->b_rptr, ira);
                        if (ipha == NULL) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                ip_drop_input("ipIfStatsInDiscards", mp, ill);
                                freemsg(mp);
                                return;
                        }
                }
                inner_ipha = (ipha_t *)((uchar_t *)ipha + ip_hdr_length);
                /*
                 * Check the sanity of the inner IP header.
                 */
                if ((IPH_HDR_VERSION(inner_ipha) != IPV4_VERSION)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        freemsg(mp);
                        return;
                }
                if (IPH_HDR_LENGTH(inner_ipha) < sizeof (ipha_t)) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        freemsg(mp);
                        return;
                }
                if (inner_ipha->ipha_src != ipha->ipha_src ||
                    inner_ipha->ipha_dst != ipha->ipha_dst) {
                        /* We fallthru to iptun fanout below */
                        goto iptun;
                }

                /*
                 * Self-encapsulated tunnel packet. Remove
                 * the outer IP header and fanout again.
                 * We also need to make sure that the inner
                 * header is pulled up until options.
                 */
                mp->b_rptr = (uchar_t *)inner_ipha;
                ipha = inner_ipha;
                ip_hdr_length = IPH_HDR_LENGTH(ipha);
                if ((uchar_t *)ipha + ip_hdr_length > mp->b_wptr) {
                        if (ira->ira_pktlen <
                            (uchar_t *)ipha + ip_hdr_length - mp->b_rptr) {
                                BUMP_MIB(ill->ill_ip_mib,
                                    ipIfStatsInTruncatedPkts);
                                ip_drop_input("ipIfStatsInTruncatedPkts",
                                    mp, ill);
                                freemsg(mp);
                                return;
                        }
                        ipha = ip_pullup(mp,
                            (uchar_t *)ipha + ip_hdr_length - mp->b_rptr, ira);
                        if (ipha == NULL) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                ip_drop_input("ipIfStatsInDiscards", mp, ill);
                                freemsg(mp);
                                return;
                        }
                }
                if (ip_hdr_length > sizeof (ipha_t)) {
                        /* We got options on the inner packet. */
                        ipaddr_t        dst = ipha->ipha_dst;
                        int             error = 0;

                        dst = ip_input_options(ipha, dst, mp, ira, &error);
                        if (error != 0) {
                                /*
                                 * An ICMP error has been sent and the packet
                                 * has been dropped.
                                 */
                                return;
                        }
                        if (dst != ipha->ipha_dst) {
                                /*
                                 * Someone put a source-route in
                                 * the inside header of a self-
                                 * encapsulated packet.  Drop it
                                 * with extreme prejudice and let
                                 * the sender know.
                                 */
                                ip_drop_input("ICMP_SOURCE_ROUTE_FAILED",
                                    mp, ill);
                                icmp_unreachable(mp, ICMP_SOURCE_ROUTE_FAILED,
                                    ira);
                                return;
                        }
                }
                if (!(ira->ira_flags & IRAF_IPSEC_SECURE)) {
                        /*
                         * This means that somebody is sending
                         * Self-encapsualted packets without AH/ESP.
                         *
                         * Send this packet to find a tunnel endpoint.
                         * if I can't find one, an ICMP
                         * PROTOCOL_UNREACHABLE will get sent.
                         */
                        protocol = ipha->ipha_protocol;
                        ira->ira_protocol = protocol;
                        goto iptun;
                }

                /* Update based on removed IP header */
                ira->ira_ip_hdr_length = ip_hdr_length;
                ira->ira_pktlen = ntohs(ipha->ipha_length);

                if (ira->ira_flags & IRAF_IPSEC_DECAPS) {
                        /*
                         * This packet is self-encapsulated multiple
                         * times. We don't want to recurse infinitely.
                         * To keep it simple, drop the packet.
                         */
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, ill);
                        freemsg(mp);
                        return;
                }
                ASSERT(ira->ira_flags & IRAF_IPSEC_SECURE);
                ira->ira_flags |= IRAF_IPSEC_DECAPS;

                ip_input_post_ipsec(mp, ira);
                return;
        }

        iptun:  /* IPPROTO_ENCAPS that is not self-encapsulated */
        case IPPROTO_IPV6:
                /* iptun will verify trusted label */
                connp = ipcl_classify_v4(mp, protocol, ip_hdr_length,
                    ira, ipst);
                if (connp != NULL) {
                        BUMP_MIB(ill->ill_ip_mib, ipIfStatsHCInDelivers);
                        ira->ira_ill = ira->ira_rill = NULL;
                        (connp->conn_recv)(connp, mp, NULL, ira);
                        CONN_DEC_REF(connp);
                        ira->ira_ill = ill;
                        ira->ira_rill = rill;
                        return;
                }
                /* FALLTHRU */
        default:
                /*
                 * On a labeled system, we have to check whether the zone
                 * itself is permitted to receive raw traffic.
                 */
                if (ira->ira_flags & IRAF_SYSTEM_LABELED) {
                        if (!tsol_can_accept_raw(mp, ira, B_FALSE)) {
                                BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
                                ip_drop_input("ipIfStatsInDiscards", mp, ill);
                                freemsg(mp);
                                return;
                        }
                }
                break;
        }

        /*
         * The above input functions may have returned the pulled up message.
         * So ipha need to be reinitialized.
         */
        ipha = (ipha_t *)mp->b_rptr;
        ira->ira_protocol = protocol = ipha->ipha_protocol;
        if (ipst->ips_ipcl_proto_fanout_v4[protocol].connf_head == NULL) {
                /*
                 * No user-level listener for these packets packets.
                 * Check for IPPROTO_ENCAP...
                 */
                if (protocol == IPPROTO_ENCAP && ipst->ips_ip_g_mrouter) {
                        /*
                         * Check policy here,
                         * THEN ship off to ip_mroute_decap().
                         *
                         * BTW,  If I match a configured IP-in-IP
                         * tunnel above, this path will not be reached, and
                         * ip_mroute_decap will never be called.
                         */
                        mp = ipsec_check_global_policy(mp, connp,
                            ipha, NULL, ira, ns);
                        if (mp != NULL) {
                                ip_mroute_decap(mp, ira);
                        } /* Else we already freed everything! */
                } else {
                        ip_proto_not_sup(mp, ira);
                }
                return;
        }

        /*
         * Handle fanout to raw sockets.  There
         * can be more than one stream bound to a particular
         * protocol.  When this is the case, each one gets a copy
         * of any incoming packets.
         */
        ASSERT(ira->ira_protocol == ipha->ipha_protocol);
        ip_fanout_proto_v4(mp, ipha, ira);
        return;

discard:
        BUMP_MIB(ill->ill_ip_mib, ipIfStatsInDiscards);
        ip_drop_input("ipIfStatsInDiscards", mp, ill);
        freemsg(mp);
#undef rptr
}