docs/how-to-build.md: use proper markup for directory names

[unleashed/tickless.git] / kernel / net / sctp / sctp.c

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

/*
 * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/strsubr.h>
#include <sys/stropts.h>
#include <sys/strsun.h>
#define _SUN_TPI_VERSION 2
#include <sys/tihdr.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/xti_inet.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/vtrace.h>
#include <sys/kmem.h>
#include <sys/cpuvar.h>
#include <sys/random.h>
#include <sys/priv.h>
#include <sys/sunldi.h>

#include <sys/errno.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <sys/isa_defs.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet/sctp.h>
#include <net/if.h>

#include <inet/common.h>
#include <inet/ip.h>
#include <inet/ip_if.h>
#include <inet/ip_ire.h>
#include <inet/ip6.h>
#include <inet/mi.h>
#include <inet/mib2.h>
#include <inet/kstatcom.h>
#include <inet/optcom.h>
#include <inet/ipclassifier.h>
#include <inet/ipsec_impl.h>
#include <inet/sctp_ip.h>
#include <inet/sctp_crc32.h>

#include <inet/sctp/sctp_impl.h>
#include <inet/sctp/sctp_addr.h>
#include <inet/sctp/sctp_asconf.h>

int sctpdebug;
sin6_t  sctp_sin6_null; /* Zero address for quick clears */

static void     sctp_closei_local(sctp_t *sctp);
static int      sctp_init_values(sctp_t *, sctp_t *, int);
static void     sctp_icmp_error_ipv6(sctp_t *sctp, mblk_t *mp);
static void     sctp_process_recvq(void *);
static void     sctp_rq_tq_init(sctp_stack_t *);
static void     sctp_rq_tq_fini(sctp_stack_t *);
static void     sctp_conn_cache_init();
static void     sctp_conn_cache_fini();
static int      sctp_conn_cache_constructor();
static void     sctp_conn_cache_destructor();
static void     sctp_conn_clear(conn_t *);
static void     sctp_notify(void *, ip_xmit_attr_t *, ixa_notify_type_t,
    ixa_notify_arg_t);

static void     *sctp_stack_init(netstackid_t stackid, netstack_t *ns);
static void     sctp_stack_fini(netstackid_t stackid, void *arg);

/*
 * SCTP receive queue taskq
 *
 * At SCTP initialization time, a default taskq is created for
 * servicing packets received when the interrupt thread cannot
 * get a hold on the sctp_t.  The number of taskq can be increased in
 * sctp_find_next_tq() when an existing taskq cannot be dispatched.
 * The taskqs are never removed.  But the max number of taskq which
 * can be created is controlled by sctp_recvq_tq_list_max_sz.  Note
 * that SCTP recvq taskq is not tied to any specific CPU or ill.
 *
 * Those taskqs are stored in an array recvq_tq_list.  And they are
 * used in a round robin fashion.  The current taskq being used is
 * determined by recvq_tq_list_cur.
 */

/* /etc/system variables */
/* The minimum number of threads for each taskq. */
int sctp_recvq_tq_thr_min = 4;
/* The maximum number of threads for each taskq. */
int sctp_recvq_tq_thr_max = 48;
/* The mnimum number of tasks for each taskq. */
int sctp_recvq_tq_task_min = 8;
/* Default value of sctp_recvq_tq_list_max_sz. */
int sctp_recvq_tq_list_max = 16;

/*
 * SCTP tunables related declarations. Definitions are in sctp_tunables.c
 */
extern mod_prop_info_t sctp_propinfo_tbl[];
extern int sctp_propinfo_count;

/*  sctp_t/conn_t kmem cache */
struct kmem_cache       *sctp_conn_cache;

#define SCTP_CONDEMNED(sctp)                            \
        mutex_enter(&(sctp)->sctp_reflock);             \
        ((sctp)->sctp_condemned = B_TRUE);              \
        mutex_exit(&(sctp)->sctp_reflock);

/* Link/unlink a sctp_t to/from the global list. */
#define SCTP_LINK(sctp, sctps)                          \
        mutex_enter(&(sctps)->sctps_g_lock);            \
        list_insert_tail(&sctps->sctps_g_list, (sctp)); \
        mutex_exit(&(sctps)->sctps_g_lock);

#define SCTP_UNLINK(sctp, sctps)                                \
        mutex_enter(&(sctps)->sctps_g_lock);            \
        ASSERT((sctp)->sctp_condemned);                 \
        list_remove(&(sctps)->sctps_g_list, (sctp));    \
        mutex_exit(&(sctps)->sctps_g_lock);

/*
 * Return the version number of the SCTP kernel interface.
 */
int
sctp_itf_ver(int cl_ver)
{
        if (cl_ver != SCTP_ITF_VER)
                return (-1);
        return (SCTP_ITF_VER);
}

/*
 * Called when we need a new sctp instantiation but don't really have a
 * new q to hang it off of. Copy the priv flag from the passed in structure.
 */
sctp_t *
sctp_create_eager(sctp_t *psctp)
{
        sctp_t  *sctp;
        mblk_t  *ack_mp, *hb_mp;
        conn_t  *connp;
        cred_t  *credp;
        sctp_stack_t    *sctps = psctp->sctp_sctps;

        if ((connp = ipcl_conn_create(IPCL_SCTPCONN, KM_NOSLEEP,
            sctps->sctps_netstack)) == NULL) {
                return (NULL);
        }

        sctp = CONN2SCTP(connp);
        sctp->sctp_sctps = sctps;

        if ((ack_mp = sctp_timer_alloc(sctp, sctp_ack_timer,
            KM_NOSLEEP)) == NULL ||
            (hb_mp = sctp_timer_alloc(sctp, sctp_heartbeat_timer,
            KM_NOSLEEP)) == NULL) {
                if (ack_mp != NULL)
                        freeb(ack_mp);
                sctp_conn_clear(connp);
                sctp->sctp_sctps = NULL;
                kmem_cache_free(sctp_conn_cache, connp);
                return (NULL);
        }

        sctp->sctp_ack_mp = ack_mp;
        sctp->sctp_heartbeat_mp = hb_mp;

        if (sctp_init_values(sctp, psctp, KM_NOSLEEP) != 0) {
                freeb(ack_mp);
                freeb(hb_mp);
                sctp_conn_clear(connp);
                sctp->sctp_sctps = NULL;
                kmem_cache_free(sctp_conn_cache, connp);
                return (NULL);
        }

        if ((credp = psctp->sctp_connp->conn_cred) != NULL) {
                connp->conn_cred = credp;
                crhold(credp);
        }

        sctp->sctp_mss = psctp->sctp_mss;
        sctp->sctp_detached = B_TRUE;
        /*
         * Link to the global as soon as possible so that this sctp_t
         * can be found.
         */
        SCTP_LINK(sctp, sctps);

        /* If the listener has a limit, inherit the counter info. */
        sctp->sctp_listen_cnt = psctp->sctp_listen_cnt;

        return (sctp);
}

/*
 * We are dying for some reason.  Try to do it gracefully.
 */
void
sctp_clean_death(sctp_t *sctp, int err)
{
        ASSERT(sctp != NULL);

        dprint(3, ("sctp_clean_death %p, state %d\n", (void *)sctp,
            sctp->sctp_state));

        sctp->sctp_client_errno = err;
        /*
         * Check to see if we need to notify upper layer.
         */
        if ((sctp->sctp_state >= SCTPS_COOKIE_WAIT) &&
            !SCTP_IS_DETACHED(sctp)) {
                if (sctp->sctp_xmit_head || sctp->sctp_xmit_unsent) {
                        sctp_regift_xmitlist(sctp);
                }
                if (sctp->sctp_ulp_disconnected(sctp->sctp_ulpd, 0, err)) {
                        /*
                         * Socket is gone, detach.
                         */
                        sctp->sctp_detached = B_TRUE;
                        sctp->sctp_ulpd = NULL;
                        sctp->sctp_upcalls = NULL;
                }
        }

        /* Remove this sctp from all hashes. */
        sctp_closei_local(sctp);

        /*
         * If the sctp_t is detached, we need to finish freeing up
         * the resources.  At this point, ip_fanout_sctp() should have
         * a hold on this sctp_t.  Some thread doing snmp stuff can
         * have a hold.  And a taskq can also have a hold waiting to
         * work.  sctp_unlink() the sctp_t from the global list so
         * that no new thread can find it.  Then do a SCTP_REFRELE().
         * The sctp_t will be freed after all those threads are done.
         */
        if (SCTP_IS_DETACHED(sctp)) {
                SCTP_CONDEMNED(sctp);
                SCTP_REFRELE(sctp);
        }
}

/*
 * Called by upper layer when it wants to close this association.
 * Depending on the state of this assoication, we need to do
 * different things.
 *
 * If the state is below COOKIE_ECHOED or it is COOKIE_ECHOED but with
 * no sent data, just remove this sctp from all the hashes.  This
 * makes sure that all packets from the other end will go to the default
 * sctp handling.  The upper layer will then do a sctp_close() to clean
 * up.
 *
 * Otherwise, check and see if SO_LINGER is set.  If it is set, check
 * the value.  If the value is 0, consider this an abortive close.  Send
 * an ABORT message and kill the associatiion.
 *
 */
int
sctp_disconnect(sctp_t *sctp)
{
        int             error = 0;
        conn_t          *connp = sctp->sctp_connp;

        dprint(3, ("sctp_disconnect %p, state %d\n", (void *)sctp,
            sctp->sctp_state));

        RUN_SCTP(sctp);

        switch (sctp->sctp_state) {
        case SCTPS_IDLE:
        case SCTPS_BOUND:
        case SCTPS_LISTEN:
                break;
        case SCTPS_COOKIE_WAIT:
        case SCTPS_COOKIE_ECHOED:
                /*
                 * Close during the connect 3-way handshake
                 * but here there may or may not be pending data
                 * already on queue. Process almost same as in
                 * the ESTABLISHED state.
                 */
                if (sctp->sctp_xmit_head == NULL &&
                    sctp->sctp_xmit_unsent == NULL) {
                        break;
                }
                /* FALLTHRU */
        default:
                /*
                 * If SO_LINGER has set a zero linger time, terminate the
                 * association and send an ABORT.
                 */
                if (connp->conn_linger && connp->conn_lingertime == 0) {
                        sctp_user_abort(sctp, NULL);
                        WAKE_SCTP(sctp);
                        return (error);
                }

                /*
                 * If there is unread data, send an ABORT and terminate the
                 * association.
                 */
                if (sctp->sctp_rxqueued > 0 || sctp->sctp_ulp_rxqueued > 0) {
                        sctp_user_abort(sctp, NULL);
                        WAKE_SCTP(sctp);
                        return (error);
                }
                /*
                 * Transmit the shutdown before detaching the sctp_t.
                 * After sctp_detach returns this queue/perimeter
                 * no longer owns the sctp_t thus others can modify it.
                 */
                sctp_send_shutdown(sctp, 0);

                /* Pass gathered wisdom to IP for keeping */
                sctp_update_dce(sctp);

                /*
                 * If lingering on close then wait until the shutdown
                 * is complete, or the SO_LINGER time passes, or an
                 * ABORT is sent/received.  Note that sctp_disconnect()
                 * can be called more than once.  Make sure that only
                 * one thread waits.
                 */
                if (connp->conn_linger && connp->conn_lingertime > 0 &&
                    sctp->sctp_state >= SCTPS_ESTABLISHED &&
                    !sctp->sctp_lingering) {
                        clock_t stoptime;       /* in ticks */
                        clock_t ret;

                        sctp->sctp_lingering = 1;
                        sctp->sctp_client_errno = 0;
                        stoptime = ddi_get_lbolt() +
                            connp->conn_lingertime * hz;

                        mutex_enter(&sctp->sctp_lock);
                        sctp->sctp_running = B_FALSE;
                        while (sctp->sctp_state >= SCTPS_ESTABLISHED &&
                            sctp->sctp_client_errno == 0) {
                                cv_signal(&sctp->sctp_cv);
                                ret = cv_timedwait_sig(&sctp->sctp_cv,
                                    &sctp->sctp_lock, stoptime);
                                if (ret < 0) {
                                        /* Stoptime has reached. */
                                        sctp->sctp_client_errno = EWOULDBLOCK;
                                        break;
                                } else if (ret == 0) {
                                        /* Got a signal. */
                                        break;
                                }
                        }
                        error = sctp->sctp_client_errno;
                        sctp->sctp_client_errno = 0;
                        mutex_exit(&sctp->sctp_lock);
                }

                WAKE_SCTP(sctp);
                return (error);
        }


        /* Remove this sctp from all hashes so nobody can find it. */
        sctp_closei_local(sctp);
        WAKE_SCTP(sctp);
        return (error);
}

void
sctp_close(sctp_t *sctp)
{
        dprint(3, ("sctp_close %p, state %d\n", (void *)sctp,
            sctp->sctp_state));

        RUN_SCTP(sctp);
        sctp->sctp_detached = 1;
        sctp->sctp_ulpd = NULL;
        sctp->sctp_upcalls = NULL;
        bzero(&sctp->sctp_events, sizeof (sctp->sctp_events));

        /* If the graceful shutdown has not been completed, just return. */
        if (sctp->sctp_state != SCTPS_IDLE) {
                WAKE_SCTP(sctp);
                return;
        }

        /*
         * Since sctp_t is in SCTPS_IDLE state, so the only thread which
         * can have a hold on the sctp_t is doing snmp stuff.  Just do
         * a SCTP_REFRELE() here after the SCTP_UNLINK().  It will
         * be freed when the other thread is done.
         */
        SCTP_CONDEMNED(sctp);
        WAKE_SCTP(sctp);
        SCTP_REFRELE(sctp);
}

/*
 * Unlink from global list and do the eager close.
 * Remove the refhold implicit in being on the global list.
 */
void
sctp_close_eager(sctp_t *sctp)
{
        SCTP_CONDEMNED(sctp);
        sctp_closei_local(sctp);
        SCTP_REFRELE(sctp);
}

/*
 * The sctp_t is going away. Remove it from all lists and set it
 * to SCTPS_IDLE. The caller has to remove it from the
 * global list. The freeing up of memory is deferred until
 * sctp_free(). This is needed since a thread in sctp_input() might have
 * done a SCTP_REFHOLD on this structure before it was removed from the
 * hashes.
 */
static void
sctp_closei_local(sctp_t *sctp)
{
        mblk_t  *mp;
        conn_t  *connp = sctp->sctp_connp;

        /* The counter is incremented only for established associations. */
        if (sctp->sctp_state >= SCTPS_ESTABLISHED)
                SCTPS_ASSOC_DEC(sctp->sctp_sctps);

        if (sctp->sctp_listen_cnt != NULL)
                SCTP_DECR_LISTEN_CNT(sctp);

        /* Sanity check, don't do the same thing twice.  */
        if (connp->conn_state_flags & CONN_CLOSING) {
                ASSERT(sctp->sctp_state == SCTPS_IDLE);
                return;
        }

        /* Stop and free the timers */
        sctp_free_faddr_timers(sctp);
        if ((mp = sctp->sctp_heartbeat_mp) != NULL) {
                sctp_timer_free(mp);
                sctp->sctp_heartbeat_mp = NULL;
        }
        if ((mp = sctp->sctp_ack_mp) != NULL) {
                sctp_timer_free(mp);
                sctp->sctp_ack_mp = NULL;
        }

        /* Set the CONN_CLOSING flag so that IP will not cache IRE again. */
        mutex_enter(&connp->conn_lock);
        connp->conn_state_flags |= CONN_CLOSING;
        mutex_exit(&connp->conn_lock);

        /* Remove from all hashes. */
        sctp_bind_hash_remove(sctp);
        sctp_conn_hash_remove(sctp);
        sctp_listen_hash_remove(sctp);
        sctp->sctp_state = SCTPS_IDLE;

        /*
         * Clean up the recvq as much as possible.  All those packets
         * will be silently dropped as this sctp_t is now in idle state.
         */
        mutex_enter(&sctp->sctp_recvq_lock);
        while ((mp = sctp->sctp_recvq) != NULL) {
                sctp->sctp_recvq = mp->b_next;
                mp->b_next = NULL;

                if (ip_recv_attr_is_mblk(mp))
                        mp = ip_recv_attr_free_mblk(mp);

                freemsg(mp);
        }
        mutex_exit(&sctp->sctp_recvq_lock);
}

/*
 * Free memory associated with the sctp/ip header template.
 */
static void
sctp_headers_free(sctp_t *sctp)
{
        if (sctp->sctp_iphc != NULL) {
                kmem_free(sctp->sctp_iphc, sctp->sctp_iphc_len);
                sctp->sctp_iphc = NULL;
                sctp->sctp_ipha = NULL;
                sctp->sctp_hdr_len = 0;
                sctp->sctp_ip_hdr_len = 0;
                sctp->sctp_iphc_len = 0;
                sctp->sctp_sctph = NULL;
                sctp->sctp_hdr_len = 0;
        }
        if (sctp->sctp_iphc6 != NULL) {
                kmem_free(sctp->sctp_iphc6, sctp->sctp_iphc6_len);
                sctp->sctp_iphc6 = NULL;
                sctp->sctp_ip6h = NULL;
                sctp->sctp_hdr6_len = 0;
                sctp->sctp_ip_hdr6_len = 0;
                sctp->sctp_iphc6_len = 0;
                sctp->sctp_sctph6 = NULL;
                sctp->sctp_hdr6_len = 0;
        }
}

static void
sctp_free_xmit_data(sctp_t *sctp)
{
        mblk_t  *ump = NULL;
        mblk_t  *nump;
        mblk_t  *mp;
        mblk_t  *nmp;

        sctp->sctp_xmit_unacked = NULL;
        ump = sctp->sctp_xmit_head;
        sctp->sctp_xmit_tail = sctp->sctp_xmit_head = NULL;
free_unsent:
        for (; ump != NULL; ump = nump) {
                for (mp = ump->b_cont; mp != NULL; mp = nmp) {
                        nmp = mp->b_next;
                        mp->b_next = NULL;
                        mp->b_prev = NULL;
                        freemsg(mp);
                }
                ASSERT(DB_REF(ump) == 1);
                nump = ump->b_next;
                ump->b_next = NULL;
                ump->b_prev = NULL;
                ump->b_cont = NULL;
                freeb(ump);
        }
        if ((ump = sctp->sctp_xmit_unsent) == NULL) {
                ASSERT(sctp->sctp_xmit_unsent_tail == NULL);
                return;
        }
        sctp->sctp_xmit_unsent = sctp->sctp_xmit_unsent_tail = NULL;
        goto free_unsent;
}

/*
 * Cleanup all the messages in the stream queue and the reassembly lists.
 * If 'free' is true, then delete the streams as well.
 */
void
sctp_instream_cleanup(sctp_t *sctp, boolean_t free)
{
        int     i;
        mblk_t  *mp;
        mblk_t  *mp1;

        if (sctp->sctp_instr != NULL) {
                /* walk thru and flush out anything remaining in the Q */
                for (i = 0; i < sctp->sctp_num_istr; i++) {
                        mp = sctp->sctp_instr[i].istr_msgs;
                        while (mp != NULL) {
                                mp1 = mp->b_next;
                                mp->b_next = mp->b_prev = NULL;
                                freemsg(mp);
                                mp = mp1;
                        }
                        sctp->sctp_instr[i].istr_msgs = NULL;
                        sctp->sctp_instr[i].istr_nmsgs = 0;
                        sctp_free_reass((sctp->sctp_instr) + i);
                        sctp->sctp_instr[i].nextseq = 0;
                }
                if (free) {
                        kmem_free(sctp->sctp_instr,
                            sizeof (*sctp->sctp_instr) * sctp->sctp_num_istr);
                        sctp->sctp_instr = NULL;
                        sctp->sctp_num_istr = 0;
                }
        }
        /* un-ordered fragments */
        if (sctp->sctp_uo_frags != NULL) {
                for (mp = sctp->sctp_uo_frags; mp != NULL; mp = mp1) {
                        mp1 = mp->b_next;
                        mp->b_next = mp->b_prev = NULL;
                        freemsg(mp);
                }
                sctp->sctp_uo_frags = NULL;
        }
}

/*
 * Last reference to the sctp_t is gone. Free all memory associated with it.
 * Called from SCTP_REFRELE. Called inline in sctp_close()
 */
void
sctp_free(conn_t *connp)
{
        sctp_t *sctp = CONN2SCTP(connp);
        int             cnt;
        sctp_stack_t    *sctps = sctp->sctp_sctps;

        ASSERT(sctps != NULL);
        /* Unlink it from the global list */
        SCTP_UNLINK(sctp, sctps);

        ASSERT(connp->conn_ref == 0);
        ASSERT(connp->conn_proto == IPPROTO_SCTP);
        ASSERT(!MUTEX_HELD(&sctp->sctp_reflock));
        ASSERT(sctp->sctp_refcnt == 0);

        ASSERT(sctp->sctp_ptpbhn == NULL && sctp->sctp_bind_hash == NULL);
        ASSERT(sctp->sctp_conn_hash_next == NULL &&
            sctp->sctp_conn_hash_prev == NULL);


        /* Free up all the resources. */

        /* blow away sctp stream management */
        if (sctp->sctp_ostrcntrs != NULL) {
                kmem_free(sctp->sctp_ostrcntrs,
                    sizeof (uint16_t) * sctp->sctp_num_ostr);
                sctp->sctp_ostrcntrs = NULL;
        }
        sctp_instream_cleanup(sctp, B_TRUE);

        /* Remove all data transfer resources. */
        sctp->sctp_istr_nmsgs = 0;
        sctp->sctp_rxqueued = 0;
        sctp_free_xmit_data(sctp);
        sctp->sctp_unacked = 0;
        sctp->sctp_unsent = 0;
        if (sctp->sctp_cxmit_list != NULL)
                sctp_asconf_free_cxmit(sctp, NULL);

        sctp->sctp_lastdata = NULL;

        /* Clear out default xmit settings */
        sctp->sctp_def_stream = 0;
        sctp->sctp_def_flags = 0;
        sctp->sctp_def_ppid = 0;
        sctp->sctp_def_context = 0;
        sctp->sctp_def_timetolive = 0;

        if (sctp->sctp_sack_info != NULL) {
                sctp_free_set(sctp->sctp_sack_info);
                sctp->sctp_sack_info = NULL;
        }
        sctp->sctp_sack_gaps = 0;

        if (sctp->sctp_cookie_mp != NULL) {
                freemsg(sctp->sctp_cookie_mp);
                sctp->sctp_cookie_mp = NULL;
        }

        /* Remove all the address resources. */
        sctp_zap_addrs(sctp);
        for (cnt = 0; cnt < SCTP_IPIF_HASH; cnt++) {
                ASSERT(sctp->sctp_saddrs[cnt].ipif_count == 0);
                list_destroy(&sctp->sctp_saddrs[cnt].sctp_ipif_list);
        }

        if (sctp->sctp_hopopts != NULL) {
                mi_free(sctp->sctp_hopopts);
                sctp->sctp_hopopts = NULL;
                sctp->sctp_hopoptslen = 0;
        }
        ASSERT(sctp->sctp_hopoptslen == 0);
        if (sctp->sctp_dstopts != NULL) {
                mi_free(sctp->sctp_dstopts);
                sctp->sctp_dstopts = NULL;
                sctp->sctp_dstoptslen = 0;
        }
        ASSERT(sctp->sctp_dstoptslen == 0);
        if (sctp->sctp_rthdrdstopts != NULL) {
                mi_free(sctp->sctp_rthdrdstopts);
                sctp->sctp_rthdrdstopts = NULL;
                sctp->sctp_rthdrdstoptslen = 0;
        }
        ASSERT(sctp->sctp_rthdrdstoptslen == 0);
        if (sctp->sctp_rthdr != NULL) {
                mi_free(sctp->sctp_rthdr);
                sctp->sctp_rthdr = NULL;
                sctp->sctp_rthdrlen = 0;
        }
        ASSERT(sctp->sctp_rthdrlen == 0);
        sctp_headers_free(sctp);

        sctp->sctp_shutdown_faddr = NULL;

        if (sctp->sctp_err_chunks != NULL) {
                freemsg(sctp->sctp_err_chunks);
                sctp->sctp_err_chunks = NULL;
                sctp->sctp_err_len = 0;
        }

        /* Clear all the bitfields. */
        bzero(&sctp->sctp_bits, sizeof (sctp->sctp_bits));

        /* It is time to update the global statistics. */
        SCTPS_UPDATE_MIB(sctps, sctpOutSCTPPkts, sctp->sctp_opkts);
        SCTPS_UPDATE_MIB(sctps, sctpOutCtrlChunks, sctp->sctp_obchunks);
        SCTPS_UPDATE_MIB(sctps, sctpOutOrderChunks, sctp->sctp_odchunks);
        SCTPS_UPDATE_MIB(sctps, sctpOutUnorderChunks, sctp->sctp_oudchunks);
        SCTPS_UPDATE_MIB(sctps, sctpRetransChunks, sctp->sctp_rxtchunks);
        SCTPS_UPDATE_MIB(sctps, sctpInSCTPPkts, sctp->sctp_ipkts);
        SCTPS_UPDATE_MIB(sctps, sctpInCtrlChunks, sctp->sctp_ibchunks);
        SCTPS_UPDATE_MIB(sctps, sctpInOrderChunks, sctp->sctp_idchunks);
        SCTPS_UPDATE_MIB(sctps, sctpInUnorderChunks, sctp->sctp_iudchunks);
        SCTPS_UPDATE_MIB(sctps, sctpFragUsrMsgs, sctp->sctp_fragdmsgs);
        SCTPS_UPDATE_MIB(sctps, sctpReasmUsrMsgs, sctp->sctp_reassmsgs);
        sctp->sctp_opkts = 0;
        sctp->sctp_obchunks = 0;
        sctp->sctp_odchunks = 0;
        sctp->sctp_oudchunks = 0;
        sctp->sctp_rxtchunks = 0;
        sctp->sctp_ipkts = 0;
        sctp->sctp_ibchunks = 0;
        sctp->sctp_idchunks = 0;
        sctp->sctp_iudchunks = 0;
        sctp->sctp_fragdmsgs = 0;
        sctp->sctp_reassmsgs = 0;
        sctp->sctp_outseqtsns = 0;
        sctp->sctp_osacks = 0;
        sctp->sctp_isacks = 0;
        sctp->sctp_idupchunks = 0;
        sctp->sctp_gapcnt = 0;
        sctp->sctp_cum_obchunks = 0;
        sctp->sctp_cum_odchunks = 0;
        sctp->sctp_cum_oudchunks = 0;
        sctp->sctp_cum_rxtchunks = 0;
        sctp->sctp_cum_ibchunks = 0;
        sctp->sctp_cum_idchunks = 0;
        sctp->sctp_cum_iudchunks = 0;

        sctp->sctp_autoclose = 0;
        sctp->sctp_tx_adaptation_code = 0;

        sctp->sctp_sctps = NULL;

        sctp_conn_clear(connp);
        kmem_cache_free(sctp_conn_cache, connp);
}

/*
 * Initialize protocol control block. If a parent exists, inherit
 * all values set through setsockopt().
 */
static int
sctp_init_values(sctp_t *sctp, sctp_t *psctp, int sleep)
{
        int     err;
        int     cnt;
        sctp_stack_t    *sctps = sctp->sctp_sctps;
        conn_t  *connp;

        connp = sctp->sctp_connp;

        sctp->sctp_nsaddrs = 0;
        for (cnt = 0; cnt < SCTP_IPIF_HASH; cnt++) {
                sctp->sctp_saddrs[cnt].ipif_count = 0;
                list_create(&sctp->sctp_saddrs[cnt].sctp_ipif_list,
                    sizeof (sctp_saddr_ipif_t), offsetof(sctp_saddr_ipif_t,
                    saddr_ipif));
        }
        connp->conn_ports = 0;
        sctp->sctp_running = B_FALSE;
        sctp->sctp_state = SCTPS_IDLE;

        sctp->sctp_refcnt = 1;

        sctp->sctp_strikes = 0;

        sctp->sctp_last_mtu_probe = ddi_get_lbolt64();
        sctp->sctp_mtu_probe_intvl = sctps->sctps_mtu_probe_interval;

        sctp->sctp_sack_gaps = 0;
        /* So we will not delay sending the first SACK. */
        sctp->sctp_sack_toggle = sctps->sctps_deferred_acks_max;

        /* Only need to do the allocation if there is no "cached" one. */
        if (sctp->sctp_pad_mp == NULL) {
                if (sleep == KM_SLEEP) {
                        sctp->sctp_pad_mp = allocb_wait(SCTP_ALIGN, BPRI_MED,
                            STR_NOSIG, NULL);
                } else {
                        sctp->sctp_pad_mp = allocb(SCTP_ALIGN, BPRI_MED);
                        if (sctp->sctp_pad_mp == NULL)
                                return (ENOMEM);
                }
                bzero(sctp->sctp_pad_mp->b_rptr, SCTP_ALIGN);
        }

        if (psctp != NULL) {
                /*
                 * Inherit from parent
                 *
                 * Start by inheriting from the conn_t, including conn_ixa and
                 * conn_xmit_ipp.
                 */
                err = conn_inherit_parent(psctp->sctp_connp, connp);
                if (err != 0)
                        goto failure;

                sctp->sctp_upcalls = psctp->sctp_upcalls;

                sctp->sctp_cookie_lifetime = psctp->sctp_cookie_lifetime;

                sctp->sctp_cwnd_max = psctp->sctp_cwnd_max;
                sctp->sctp_rwnd = psctp->sctp_rwnd;
                sctp->sctp_arwnd = psctp->sctp_arwnd;
                sctp->sctp_pd_point = psctp->sctp_pd_point;
                sctp->sctp_rto_max = psctp->sctp_rto_max;
                sctp->sctp_rto_max_init = psctp->sctp_rto_max_init;
                sctp->sctp_rto_min = psctp->sctp_rto_min;
                sctp->sctp_rto_initial = psctp->sctp_rto_initial;
                sctp->sctp_pa_max_rxt = psctp->sctp_pa_max_rxt;
                sctp->sctp_pp_max_rxt = psctp->sctp_pp_max_rxt;
                sctp->sctp_max_init_rxt = psctp->sctp_max_init_rxt;

                sctp->sctp_def_stream = psctp->sctp_def_stream;
                sctp->sctp_def_flags = psctp->sctp_def_flags;
                sctp->sctp_def_ppid = psctp->sctp_def_ppid;
                sctp->sctp_def_context = psctp->sctp_def_context;
                sctp->sctp_def_timetolive = psctp->sctp_def_timetolive;

                sctp->sctp_num_istr = psctp->sctp_num_istr;
                sctp->sctp_num_ostr = psctp->sctp_num_ostr;

                sctp->sctp_hb_interval = psctp->sctp_hb_interval;
                sctp->sctp_autoclose = psctp->sctp_autoclose;
                sctp->sctp_tx_adaptation_code = psctp->sctp_tx_adaptation_code;

                /* xxx should be a better way to copy these flags xxx */
                sctp->sctp_bound_to_all = psctp->sctp_bound_to_all;
                sctp->sctp_cansleep = psctp->sctp_cansleep;
                sctp->sctp_send_adaptation = psctp->sctp_send_adaptation;
                sctp->sctp_ndelay = psctp->sctp_ndelay;
                sctp->sctp_events = psctp->sctp_events;
        } else {
                /*
                 * Set to system defaults
                 */
                sctp->sctp_cookie_lifetime =
                    MSEC_TO_TICK(sctps->sctps_cookie_life);
                connp->conn_sndlowat = sctps->sctps_xmit_lowat;
                connp->conn_sndbuf = sctps->sctps_xmit_hiwat;
                connp->conn_rcvbuf = sctps->sctps_recv_hiwat;

                sctp->sctp_cwnd_max = sctps->sctps_cwnd_max_;
                sctp->sctp_rwnd = connp->conn_rcvbuf;
                sctp->sctp_arwnd = connp->conn_rcvbuf;
                sctp->sctp_pd_point = sctp->sctp_rwnd;
                sctp->sctp_rto_max = MSEC_TO_TICK(sctps->sctps_rto_maxg);
                sctp->sctp_rto_max_init = sctp->sctp_rto_max;
                sctp->sctp_rto_min = MSEC_TO_TICK(sctps->sctps_rto_ming);
                sctp->sctp_rto_initial = MSEC_TO_TICK(
                    sctps->sctps_rto_initialg);
                sctp->sctp_pa_max_rxt = sctps->sctps_pa_max_retr;
                sctp->sctp_pp_max_rxt = sctps->sctps_pp_max_retr;
                sctp->sctp_max_init_rxt = sctps->sctps_max_init_retr;

                sctp->sctp_num_istr = sctps->sctps_max_in_streams;
                sctp->sctp_num_ostr = sctps->sctps_initial_out_streams;

                sctp->sctp_hb_interval =
                    MSEC_TO_TICK(sctps->sctps_heartbeat_interval);

                if (connp->conn_family == AF_INET)
                        connp->conn_default_ttl = sctps->sctps_ipv4_ttl;
                else
                        connp->conn_default_ttl = sctps->sctps_ipv6_hoplimit;

                connp->conn_xmit_ipp.ipp_unicast_hops =
                    connp->conn_default_ttl;

                /*
                 * Initialize the header template
                 */
                if ((err = sctp_build_hdrs(sctp, sleep)) != 0) {
                        goto failure;
                }
        }

        sctp->sctp_understands_asconf = B_TRUE;
        sctp->sctp_understands_addip = B_TRUE;
        sctp->sctp_prsctp_aware = B_FALSE;

        sctp->sctp_connp->conn_ref = 1;

        sctp->sctp_prsctpdrop = 0;
        sctp->sctp_msgcount = 0;

        return (0);

failure:
        sctp_headers_free(sctp);
        return (err);
}

/*
 * Extracts the init tag from an INIT chunk and checks if it matches
 * the sctp's verification tag. Returns 0 if it doesn't match, 1 if
 * it does.
 */
static boolean_t
sctp_icmp_verf(sctp_t *sctp, sctp_hdr_t *sh, mblk_t *mp)
{
        sctp_chunk_hdr_t *sch;
        uint32_t verf, *vp;

        sch = (sctp_chunk_hdr_t *)(sh + 1);
        vp = (uint32_t *)(sch + 1);

        /* Need at least the data chunk hdr and the first 4 bytes of INIT */
        if ((unsigned char *)(vp + 1) > mp->b_wptr) {
                return (B_FALSE);
        }

        bcopy(vp, &verf, sizeof (verf));

        if (verf == sctp->sctp_lvtag) {
                return (B_TRUE);
        }
        return (B_FALSE);
}

/*
 * Update the SCTP state according to change of PMTU.
 *
 * Path MTU might have changed by either increase or decrease, so need to
 * adjust the MSS based on the value of ixa_pmtu.
 */
static void
sctp_update_pmtu(sctp_t *sctp, sctp_faddr_t *fp, boolean_t decrease_only)
{
        uint32_t        pmtu;
        int32_t         mss;
        ip_xmit_attr_t  *ixa = fp->sf_ixa;

        if (sctp->sctp_state < SCTPS_ESTABLISHED)
                return;

        /*
         * Always call ip_get_pmtu() to make sure that IP has updated
         * ixa_flags properly.
         */
        pmtu = ip_get_pmtu(ixa);

        /*
         * Calculate the MSS by decreasing the PMTU by sctp_hdr_len and
         * IPsec overhead if applied. Make sure to use the most recent
         * IPsec information.
         */
        mss = pmtu - conn_ipsec_length(sctp->sctp_connp);
        if (ixa->ixa_flags & IXAF_IS_IPV4)
                mss -= sctp->sctp_hdr_len;
        else
                mss -= sctp->sctp_hdr6_len;

        /*
         * Nothing to change, so just return.
         */
        if (mss == fp->sf_pmss)
                return;

        /*
         * Currently, for ICMP errors, only PMTU decrease is handled.
         */
        if (mss > fp->sf_pmss && decrease_only)
                return;

#ifdef DEBUG
        (void) printf("sctp_update_pmtu mss from %d to %d\n",
            fp->sf_pmss, mss);
#endif
        DTRACE_PROBE2(sctp_update_pmtu, int32_t, fp->sf_pmss, uint32_t, mss);

        /*
         * Update ixa_fragsize and ixa_pmtu.
         */
        ixa->ixa_fragsize = ixa->ixa_pmtu = pmtu;

        /*
         * Make sure that sfa_pmss is a multiple of
         * SCTP_ALIGN.
         */
        fp->sf_pmss = mss & ~(SCTP_ALIGN - 1);
        fp->sf_pmtu_discovered = 1;

#ifdef notyet
        if (mss < sctp->sctp_sctps->sctps_mss_min)
                ixa->ixa_flags |= IXAF_PMTU_TOO_SMALL;
#endif
        if (ixa->ixa_flags & IXAF_PMTU_TOO_SMALL)
                ixa->ixa_flags &= ~(IXAF_DONTFRAG | IXAF_PMTU_IPV4_DF);

        /*
         * If below the min size then ip_get_pmtu cleared IXAF_PMTU_IPV4_DF.
         * Make sure to clear IXAF_DONTFRAG, which is used by IP to decide
         * whether to fragment the packet.
         */
        if (ixa->ixa_flags & IXAF_IS_IPV4) {
                if (!(ixa->ixa_flags & IXAF_PMTU_IPV4_DF)) {
                        fp->sf_df = B_FALSE;
                        if (fp == sctp->sctp_current) {
                                sctp->sctp_ipha->
                                    ipha_fragment_offset_and_flags = 0;
                        }
                }
        }
}

/*
 * Notify function registered with ip_xmit_attr_t. It's called in the context
 * of conn_ip_output so it's safe to update the SCTP state.
 * Currently only used for pmtu changes.
 */
/* ARGSUSED1 */
static void
sctp_notify(void *arg, ip_xmit_attr_t *ixa, ixa_notify_type_t ntype,
    ixa_notify_arg_t narg)
{
        sctp_t          *sctp = (sctp_t *)arg;
        sctp_faddr_t    *fp;

        switch (ntype) {
        case IXAN_PMTU:
                /* Find the faddr based on the ip_xmit_attr_t pointer */
                for (fp = sctp->sctp_faddrs; fp != NULL; fp = fp->sf_next) {
                        if (fp->sf_ixa == ixa)
                                break;
                }
                if (fp != NULL)
                        sctp_update_pmtu(sctp, fp, B_FALSE);
                break;
        default:
                break;
        }
}

/*
 * sctp_icmp_error is called by sctp_input() to process ICMP error messages
 * passed up by IP.  We need to find a sctp_t
 * that corresponds to the returned datagram.  Passes the message back in on
 * the correct queue once it has located the connection.
 * Assumes that IP has pulled up everything up to and including
 * the ICMP header.
 */
void
sctp_icmp_error(sctp_t *sctp, mblk_t *mp)
{
        icmph_t *icmph;
        ipha_t  *ipha;
        int     iph_hdr_length;
        sctp_hdr_t *sctph;
        in6_addr_t dst;
        sctp_faddr_t *fp;
        sctp_stack_t    *sctps = sctp->sctp_sctps;

        dprint(1, ("sctp_icmp_error: sctp=%p, mp=%p\n", (void *)sctp,
            (void *)mp));

        ipha = (ipha_t *)mp->b_rptr;
        if (IPH_HDR_VERSION(ipha) != IPV4_VERSION) {
                ASSERT(IPH_HDR_VERSION(ipha) == IPV6_VERSION);
                sctp_icmp_error_ipv6(sctp, mp);
                return;
        }

        /* account for the ip hdr from the icmp message */
        iph_hdr_length = IPH_HDR_LENGTH(ipha);
        icmph = (icmph_t *)&mp->b_rptr[iph_hdr_length];
        /* now the ip hdr of message resulting in this icmp */
        ipha = (ipha_t *)&icmph[1];
        iph_hdr_length = IPH_HDR_LENGTH(ipha);
        sctph = (sctp_hdr_t *)((char *)ipha + iph_hdr_length);
        /* first_mp must expose the full sctp header. */
        if ((uchar_t *)(sctph + 1) >= mp->b_wptr) {
                /* not enough data for SCTP header */
                freemsg(mp);
                return;
        }

        switch (icmph->icmph_type) {
        case ICMP_DEST_UNREACHABLE:
                switch (icmph->icmph_code) {
                case ICMP_FRAGMENTATION_NEEDED:
                        /*
                         * Reduce the MSS based on the new MTU.  This will
                         * eliminate any fragmentation locally.
                         * N.B.  There may well be some funny side-effects on
                         * the local send policy and the remote receive policy.
                         * Pending further research, we provide
                         * sctp_ignore_path_mtu just in case this proves
                         * disastrous somewhere.
                         *
                         * After updating the MSS, retransmit part of the
                         * dropped segment using the new mss by calling
                         * sctp_wput_slow().  Need to adjust all those
                         * params to make sure sctp_wput_slow() work properly.
                         */
                        if (sctps->sctps_ignore_path_mtu)
                                break;

                        /* find the offending faddr */
                        IN6_IPADDR_TO_V4MAPPED(ipha->ipha_dst, &dst);
                        fp = sctp_lookup_faddr(sctp, &dst);
                        if (fp == NULL) {
                                break;
                        }
                        sctp_update_pmtu(sctp, fp, B_TRUE);
                        /*
                         * It is possible, even likely that a fast retransmit
                         * attempt has been dropped by ip as a result of this
                         * error, retransmission bundles as much as possible.
                         * A retransmit here prevents significant delays waiting
                         * on the timer. Analogous to behaviour of TCP after
                         * ICMP too big.
                         */
                        sctp_rexmit(sctp, fp);
                        break;
                case ICMP_PORT_UNREACHABLE:
                case ICMP_PROTOCOL_UNREACHABLE:
                        switch (sctp->sctp_state) {
                        case SCTPS_COOKIE_WAIT:
                        case SCTPS_COOKIE_ECHOED:
                                /* make sure the verification tag matches */
                                if (!sctp_icmp_verf(sctp, sctph, mp)) {
                                        break;
                                }
                                SCTPS_BUMP_MIB(sctps, sctpAborted);
                                sctp_assoc_event(sctp, SCTP_CANT_STR_ASSOC, 0,
                                    NULL);
                                sctp_clean_death(sctp, ECONNREFUSED);
                                break;
                        }
                        break;
                case ICMP_HOST_UNREACHABLE:
                case ICMP_NET_UNREACHABLE:
                        /* Record the error in case we finally time out. */
                        sctp->sctp_client_errno = (icmph->icmph_code ==
                            ICMP_HOST_UNREACHABLE) ? EHOSTUNREACH : ENETUNREACH;
                        break;
                default:
                        break;
                }
                break;
        case ICMP_SOURCE_QUENCH: {
                /* Reduce the sending rate as if we got a retransmit timeout */
                break;
        }
        }
        freemsg(mp);
}

/*
 * sctp_icmp_error_ipv6() is called by sctp_icmp_error() to process ICMPv6
 * error messages passed up by IP.
 * Assumes that IP has pulled up all the extension headers as well
 * as the ICMPv6 header.
 */
static void
sctp_icmp_error_ipv6(sctp_t *sctp, mblk_t *mp)
{
        icmp6_t *icmp6;
        ip6_t   *ip6h;
        uint16_t        iph_hdr_length;
        sctp_hdr_t *sctpha;
        uint8_t *nexthdrp;
        sctp_faddr_t *fp;
        sctp_stack_t    *sctps = sctp->sctp_sctps;

        ip6h = (ip6_t *)mp->b_rptr;
        iph_hdr_length = (ip6h->ip6_nxt != IPPROTO_SCTP) ?
            ip_hdr_length_v6(mp, ip6h) : IPV6_HDR_LEN;

        icmp6 = (icmp6_t *)&mp->b_rptr[iph_hdr_length];
        ip6h = (ip6_t *)&icmp6[1];
        if (!ip_hdr_length_nexthdr_v6(mp, ip6h, &iph_hdr_length, &nexthdrp)) {
                freemsg(mp);
                return;
        }
        ASSERT(*nexthdrp == IPPROTO_SCTP);

        /* XXX need ifindex to find connection */
        sctpha = (sctp_hdr_t *)((char *)ip6h + iph_hdr_length);
        if ((uchar_t *)sctpha >= mp->b_wptr) {
                /* not enough data for SCTP header */
                freemsg(mp);
                return;
        }
        switch (icmp6->icmp6_type) {
        case ICMP6_PACKET_TOO_BIG:
                /*
                 * Reduce the MSS based on the new MTU.  This will
                 * eliminate any fragmentation locally.
                 * N.B.  There may well be some funny side-effects on
                 * the local send policy and the remote receive policy.
                 * Pending further research, we provide
                 * sctp_ignore_path_mtu just in case this proves
                 * disastrous somewhere.
                 *
                 * After updating the MSS, retransmit part of the
                 * dropped segment using the new mss by calling
                 * sctp_wput_slow().  Need to adjust all those
                 * params to make sure sctp_wput_slow() work properly.
                 */
                if (sctps->sctps_ignore_path_mtu)
                        break;

                /* find the offending faddr */
                fp = sctp_lookup_faddr(sctp, &ip6h->ip6_dst);
                if (fp == NULL) {
                        break;
                }

                sctp_update_pmtu(sctp, fp, B_TRUE);
                /*
                 * It is possible, even likely that a fast retransmit
                 * attempt has been dropped by ip as a result of this
                 * error, retransmission bundles as much as possible.
                 * A retransmit here prevents significant delays waiting
                 * on the timer. Analogous to behaviour of TCP after
                 * ICMP too big.
                 */
                sctp_rexmit(sctp, fp);
                break;

        case ICMP6_DST_UNREACH:
                switch (icmp6->icmp6_code) {
                case ICMP6_DST_UNREACH_NOPORT:
                        /* make sure the verification tag matches */
                        if (!sctp_icmp_verf(sctp, sctpha, mp)) {
                                break;
                        }
                        if (sctp->sctp_state == SCTPS_COOKIE_WAIT ||
                            sctp->sctp_state == SCTPS_COOKIE_ECHOED) {
                                SCTPS_BUMP_MIB(sctps, sctpAborted);
                                sctp_assoc_event(sctp, SCTP_CANT_STR_ASSOC, 0,
                                    NULL);
                                sctp_clean_death(sctp, ECONNREFUSED);
                        }
                        break;

                case ICMP6_DST_UNREACH_ADMIN:
                case ICMP6_DST_UNREACH_NOROUTE:
                case ICMP6_DST_UNREACH_NOTNEIGHBOR:
                case ICMP6_DST_UNREACH_ADDR:
                        /* Record the error in case we finally time out. */
                        sctp->sctp_client_errno = EHOSTUNREACH;
                        break;
                default:
                        break;
                }
                break;

        case ICMP6_PARAM_PROB:
                /* If this corresponds to an ICMP_PROTOCOL_UNREACHABLE */
                if (icmp6->icmp6_code == ICMP6_PARAMPROB_NEXTHEADER &&
                    (uchar_t *)ip6h + icmp6->icmp6_pptr ==
                    (uchar_t *)nexthdrp) {
                        /* make sure the verification tag matches */
                        if (!sctp_icmp_verf(sctp, sctpha, mp)) {
                                break;
                        }
                        if (sctp->sctp_state == SCTPS_COOKIE_WAIT) {
                                SCTPS_BUMP_MIB(sctps, sctpAborted);
                                sctp_assoc_event(sctp, SCTP_CANT_STR_ASSOC, 0,
                                    NULL);
                                sctp_clean_death(sctp, ECONNREFUSED);
                        }
                        break;
                }
                break;

        case ICMP6_TIME_EXCEEDED:
        default:
                break;
        }
        freemsg(mp);
}

/*
 * Called by sockfs to create a new sctp instance.
 *
 * If parent pointer is passed in, inherit settings from it.
 */
sctp_t *
sctp_create(void *ulpd, sctp_t *parent, int family, int type, int flags,
    sock_upcalls_t *upcalls, sctp_sockbuf_limits_t *sbl,
    cred_t *credp)
{
        sctp_t          *sctp, *psctp;
        conn_t          *connp;
        mblk_t          *ack_mp, *hb_mp;
        int             sleep = flags & SCTP_CAN_BLOCK ? KM_SLEEP : KM_NOSLEEP;
        zoneid_t        zoneid;
        sctp_stack_t    *sctps;

        /* User must supply a credential. */
        if (credp == NULL)
                return (NULL);

        psctp = (sctp_t *)parent;
        if (psctp != NULL) {
                sctps = psctp->sctp_sctps;
                /* Increase here to have common decrease at end */
                netstack_hold(sctps->sctps_netstack);
                ASSERT(sctps->sctps_recvq_tq_list_cur_sz > 0);
        } else {
                netstack_t *ns;

                ns = netstack_find_by_cred(credp);
                sctps = ns->netstack_sctp;
                /*
                 * Check if the receive queue taskq for this sctp_stack_t has
                 * been set up.
                 */
                if (sctps->sctps_recvq_tq_list_cur_sz == 0)
                        sctp_rq_tq_init(sctps);

                /*
                 * For exclusive stacks we set the zoneid to zero
                 * to make SCTP operate as if in the global zone.
                 */
                if (sctps->sctps_netstack->netstack_stackid !=
                    GLOBAL_NETSTACKID)
                        zoneid = GLOBAL_ZONEID;
                else
                        zoneid = crgetzoneid(credp);
        }
        if ((connp = ipcl_conn_create(IPCL_SCTPCONN, sleep,
            sctps->sctps_netstack)) == NULL) {
                netstack_rele(sctps->sctps_netstack);
                SCTP_KSTAT(sctps, sctp_conn_create);
                return (NULL);
        }
        /*
         * ipcl_conn_create did a netstack_hold. Undo the hold that was
         * done at top of sctp_create.
         */
        netstack_rele(sctps->sctps_netstack);
        sctp = CONN2SCTP(connp);
        sctp->sctp_sctps = sctps;

        if ((ack_mp = sctp_timer_alloc(sctp, sctp_ack_timer, sleep)) == NULL ||
            (hb_mp = sctp_timer_alloc(sctp, sctp_heartbeat_timer,
            sleep)) == NULL) {
                if (ack_mp != NULL)
                        freeb(ack_mp);
                sctp_conn_clear(connp);
                sctp->sctp_sctps = NULL;
                kmem_cache_free(sctp_conn_cache, connp);
                return (NULL);
        }

        sctp->sctp_ack_mp = ack_mp;
        sctp->sctp_heartbeat_mp = hb_mp;

        /*
         * Have conn_ip_output drop packets should our outer source
         * go invalid, and tell us about mtu changes.
         */
        connp->conn_ixa->ixa_flags |= IXAF_SET_ULP_CKSUM | IXAF_VERIFY_SOURCE |
            IXAF_VERIFY_PMTU;
        connp->conn_family = family;
        connp->conn_so_type = type;

        if (sctp_init_values(sctp, psctp, sleep) != 0) {
                freeb(ack_mp);
                freeb(hb_mp);
                sctp_conn_clear(connp);
                sctp->sctp_sctps = NULL;
                kmem_cache_free(sctp_conn_cache, connp);
                return (NULL);
        }
        sctp->sctp_cansleep = ((flags & SCTP_CAN_BLOCK) == SCTP_CAN_BLOCK);

        sctp->sctp_mss = sctps->sctps_initial_mtu - ((family == AF_INET6) ?
            sctp->sctp_hdr6_len : sctp->sctp_hdr_len);

        if (psctp != NULL) {
                conn_t  *pconnp = psctp->sctp_connp;

                RUN_SCTP(psctp);
                /*
                 * Inherit local address list, local port. Parent is either
                 * in SCTPS_BOUND, or SCTPS_LISTEN state.
                 */
                ASSERT((psctp->sctp_state == SCTPS_BOUND) ||
                    (psctp->sctp_state == SCTPS_LISTEN));
                if (sctp_dup_saddrs(psctp, sctp, sleep)) {
                        WAKE_SCTP(psctp);
                        freeb(ack_mp);
                        freeb(hb_mp);
                        sctp_headers_free(sctp);
                        sctp_conn_clear(connp);
                        sctp->sctp_sctps = NULL;
                        kmem_cache_free(sctp_conn_cache, connp);
                        return (NULL);
                }

                /*
                 * If the parent is specified, it'll be immediatelly
                 * followed by sctp_connect(). So don't add this guy to
                 * bind hash.
                 */
                connp->conn_lport = pconnp->conn_lport;
                sctp->sctp_state = SCTPS_BOUND;
                WAKE_SCTP(psctp);
        } else {
                ASSERT(connp->conn_cred == NULL);
                connp->conn_zoneid = zoneid;
                /*
                 * conn_allzones can not be set this early, hence
                 * no IPCL_ZONEID
                 */
                connp->conn_ixa->ixa_zoneid = zoneid;
                connp->conn_open_time = ddi_get_lbolt64();
                connp->conn_cred = credp;
                crhold(credp);
                connp->conn_cpid = curproc->p_pid;

                connp->conn_zone_is_global =
                    (crgetzoneid(credp) == GLOBAL_ZONEID);
        }

        /* Initialize SCTP instance values,  our verf tag must never be 0 */
        (void) random_get_pseudo_bytes((uint8_t *)&sctp->sctp_lvtag,
            sizeof (sctp->sctp_lvtag));
        if (sctp->sctp_lvtag == 0)
                sctp->sctp_lvtag = (uint32_t)gethrtime();
        ASSERT(sctp->sctp_lvtag != 0);

        sctp->sctp_ltsn = sctp->sctp_lvtag + 1;
        sctp->sctp_lcsn = sctp->sctp_ltsn;
        sctp->sctp_recovery_tsn = sctp->sctp_lastack_rxd = sctp->sctp_ltsn - 1;
        sctp->sctp_adv_pap = sctp->sctp_lastack_rxd;

        /* Information required by upper layer */
        ASSERT(ulpd != NULL);
        sctp->sctp_ulpd = ulpd;

        ASSERT(upcalls != NULL);
        sctp->sctp_upcalls = upcalls;
        ASSERT(sbl != NULL);
        /* Fill in the socket buffer limits for sctpsockfs */
        sbl->sbl_txlowat = connp->conn_sndlowat;
        sbl->sbl_txbuf = connp->conn_sndbuf;
        sbl->sbl_rxbuf = sctp->sctp_rwnd;
        sbl->sbl_rxlowat = SCTP_RECV_LOWATER;

        /* Insert this in the global list. */
        SCTP_LINK(sctp, sctps);

        return (sctp);
}

/* Run at module load time */
void
sctp_ddi_g_init(void)
{
        /* Create sctp_t/conn_t cache */
        sctp_conn_cache_init();

        /* Create the faddr cache */
        sctp_faddr_init();

        /* Create the sets cache */
        sctp_sets_init();

        /* Create the PR-SCTP sets cache */
        sctp_ftsn_sets_init();

        /* Initialize tables used for CRC calculation */
        sctp_crc32_init();

        /*
         * We want to be informed each time a stack is created or
         * destroyed in the kernel, so we can maintain the
         * set of sctp_stack_t's.
         */
        netstack_register(NS_SCTP, sctp_stack_init, NULL, sctp_stack_fini);
}

static void *
sctp_stack_init(netstackid_t stackid, netstack_t *ns)
{
        sctp_stack_t    *sctps;
        size_t          arrsz;
        int             i;

        sctps = kmem_zalloc(sizeof (*sctps), KM_SLEEP);
        sctps->sctps_netstack = ns;

        /* Initialize locks */
        mutex_init(&sctps->sctps_g_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&sctps->sctps_epriv_port_lock, NULL, MUTEX_DEFAULT, NULL);
        sctps->sctps_g_num_epriv_ports = SCTP_NUM_EPRIV_PORTS;
        sctps->sctps_g_epriv_ports[0] = ULP_DEF_EPRIV_PORT1;
        sctps->sctps_g_epriv_ports[1] = ULP_DEF_EPRIV_PORT2;

        /* Initialize SCTP hash arrays. */
        sctp_hash_init(sctps);

        arrsz = sctp_propinfo_count * sizeof (mod_prop_info_t);
        sctps->sctps_propinfo_tbl = (mod_prop_info_t *)kmem_alloc(arrsz,
            KM_SLEEP);
        bcopy(sctp_propinfo_tbl, sctps->sctps_propinfo_tbl, arrsz);

        /* saddr init */
        sctp_saddr_init(sctps);

        /* Global SCTP PCB list. */
        list_create(&sctps->sctps_g_list, sizeof (sctp_t),
            offsetof(sctp_t, sctp_list));

        /* Initialize SCTP kstats. */
        sctps->sctps_mibkp = sctp_kstat_init(stackid);
        sctps->sctps_kstat = sctp_kstat2_init(stackid);

        mutex_init(&sctps->sctps_reclaim_lock, NULL, MUTEX_DEFAULT, NULL);
        sctps->sctps_reclaim = B_FALSE;
        sctps->sctps_reclaim_tid = 0;
        sctps->sctps_reclaim_period = sctps->sctps_rto_maxg;

        /* Allocate the per netstack stats */
        mutex_enter(&cpu_lock);
        sctps->sctps_sc_cnt = MAX(ncpus, boot_ncpus);
        mutex_exit(&cpu_lock);
        sctps->sctps_sc = kmem_zalloc(max_ncpus  * sizeof (sctp_stats_cpu_t *),
            KM_SLEEP);
        for (i = 0; i < sctps->sctps_sc_cnt; i++) {
                sctps->sctps_sc[i] = kmem_zalloc(sizeof (sctp_stats_cpu_t),
                    KM_SLEEP);
        }

        mutex_init(&sctps->sctps_listener_conf_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&sctps->sctps_listener_conf, sizeof (sctp_listener_t),
            offsetof(sctp_listener_t, sl_link));

        return (sctps);
}

/*
 * Called when the module is about to be unloaded.
 */
void
sctp_ddi_g_destroy(void)
{
        /* Destroy sctp_t/conn_t caches */
        sctp_conn_cache_fini();

        /* Destroy the faddr cache */
        sctp_faddr_fini();

        /* Destroy the sets cache */
        sctp_sets_fini();

        /* Destroy the PR-SCTP sets cache */
        sctp_ftsn_sets_fini();

        netstack_unregister(NS_SCTP);
}

/*
 * Free the SCTP stack instance.
 */
static void
sctp_stack_fini(netstackid_t stackid, void *arg)
{
        sctp_stack_t *sctps = (sctp_stack_t *)arg;
        int i;

        /*
         * Set sctps_reclaim to false tells sctp_reclaim_timer() not to restart
         * the timer.
         */
        mutex_enter(&sctps->sctps_reclaim_lock);
        sctps->sctps_reclaim = B_FALSE;
        mutex_exit(&sctps->sctps_reclaim_lock);
        if (sctps->sctps_reclaim_tid != 0)
                (void) untimeout(sctps->sctps_reclaim_tid);
        mutex_destroy(&sctps->sctps_reclaim_lock);

        sctp_listener_conf_cleanup(sctps);

        kmem_free(sctps->sctps_propinfo_tbl,
            sctp_propinfo_count * sizeof (mod_prop_info_t));
        sctps->sctps_propinfo_tbl = NULL;

        /* Destroy the recvq taskqs. */
        sctp_rq_tq_fini(sctps);

        /* Destroy saddr  */
        sctp_saddr_fini(sctps);

        /* Global SCTP PCB list. */
        list_destroy(&sctps->sctps_g_list);

        /* Destroy SCTP hash arrays. */
        sctp_hash_destroy(sctps);

        /* Destroy SCTP kernel stats. */
        for (i = 0; i < sctps->sctps_sc_cnt; i++)
                kmem_free(sctps->sctps_sc[i], sizeof (sctp_stats_cpu_t));
        kmem_free(sctps->sctps_sc, max_ncpus * sizeof (sctp_stats_cpu_t *));

        sctp_kstat_fini(stackid, sctps->sctps_mibkp);
        sctps->sctps_mibkp = NULL;
        sctp_kstat2_fini(stackid, sctps->sctps_kstat);
        sctps->sctps_kstat = NULL;

        mutex_destroy(&sctps->sctps_g_lock);
        mutex_destroy(&sctps->sctps_epriv_port_lock);

        kmem_free(sctps, sizeof (*sctps));
}

static void
sctp_rq_tq_init(sctp_stack_t *sctps)
{
        char tq_name[TASKQ_NAMELEN];
        int thrs;
        int max_tasks;

        mutex_enter(&sctps->sctps_g_lock);
        /* Someone may have beaten us in creating the taskqs. */
        if (sctps->sctps_recvq_tq_list_cur_sz > 0) {
                mutex_exit(&sctps->sctps_g_lock);
                return;
        }

        thrs = MIN(sctp_recvq_tq_thr_max, MAX(sctp_recvq_tq_thr_min,
            MAX(ncpus, boot_ncpus)));
        /*
         * Make sure that the maximum number of tasks is at least thrice as
         * large as the number of threads.
         */
        max_tasks = MAX(sctp_recvq_tq_task_min, thrs) * 3;

        /*
         * This helps differentiate the default taskqs in different IP stacks.
         */
        (void) snprintf(tq_name, sizeof (tq_name), "sctp_def_rq_taskq_%d",
            sctps->sctps_netstack->netstack_stackid);

        sctps->sctps_recvq_tq_list_max_sz = sctp_recvq_tq_list_max;
        sctps->sctps_recvq_tq_list_cur_sz = 1;

        /*
         * Initialize the recvq_tq_list and create the first recvq taskq.
         * What to do if it fails?
         */
        sctps->sctps_recvq_tq_list =
            kmem_zalloc(sctps->sctps_recvq_tq_list_max_sz * sizeof (taskq_t *),
            KM_SLEEP);
        sctps->sctps_recvq_tq_list[0] = taskq_create(tq_name, thrs,
            minclsyspri, sctp_recvq_tq_task_min, max_tasks, TASKQ_PREPOPULATE);
        mutex_init(&sctps->sctps_rq_tq_lock, NULL, MUTEX_DEFAULT, NULL);

        mutex_exit(&sctps->sctps_g_lock);
}

static void
sctp_rq_tq_fini(sctp_stack_t *sctps)
{
        int i;

        if (sctps->sctps_recvq_tq_list_cur_sz == 0)
                return;

        for (i = 0; i < sctps->sctps_recvq_tq_list_cur_sz; i++) {
                ASSERT(sctps->sctps_recvq_tq_list[i] != NULL);
                taskq_destroy(sctps->sctps_recvq_tq_list[i]);
        }
        kmem_free(sctps->sctps_recvq_tq_list,
            sctps->sctps_recvq_tq_list_max_sz * sizeof (taskq_t *));
        sctps->sctps_recvq_tq_list = NULL;
}

/* Add another taskq for a new ill. */
void
sctp_inc_taskq(sctp_stack_t *sctps)
{
        taskq_t *tq;
        char tq_name[TASKQ_NAMELEN];
        int thrs;
        int max_tasks;

        thrs = MIN(sctp_recvq_tq_thr_max, MAX(sctp_recvq_tq_thr_min,
            MAX(ncpus, boot_ncpus)));
        /*
         * Make sure that the maximum number of tasks is at least thrice as
         * large as the number of threads.
         */
        max_tasks = MAX(sctp_recvq_tq_task_min, thrs) * 3;

        mutex_enter(&sctps->sctps_rq_tq_lock);
        if (sctps->sctps_recvq_tq_list_cur_sz + 1 >
            sctps->sctps_recvq_tq_list_max_sz) {
                mutex_exit(&sctps->sctps_rq_tq_lock);
                cmn_err(CE_NOTE, "Cannot create more SCTP recvq taskq");
                return;
        }

        (void) snprintf(tq_name, sizeof (tq_name), "sctp_rq_taskq_%d_%u",
            sctps->sctps_netstack->netstack_stackid,
            sctps->sctps_recvq_tq_list_cur_sz);
        tq = taskq_create(tq_name, thrs, minclsyspri, sctp_recvq_tq_task_min,
            max_tasks, TASKQ_PREPOPULATE);
        if (tq == NULL) {
                mutex_exit(&sctps->sctps_rq_tq_lock);
                cmn_err(CE_NOTE, "SCTP recvq taskq creation failed");
                return;
        }
        ASSERT(sctps->sctps_recvq_tq_list[
            sctps->sctps_recvq_tq_list_cur_sz] == NULL);
        sctps->sctps_recvq_tq_list[sctps->sctps_recvq_tq_list_cur_sz] = tq;
        atomic_inc_32(&sctps->sctps_recvq_tq_list_cur_sz);
        mutex_exit(&sctps->sctps_rq_tq_lock);
}

#ifdef DEBUG
uint32_t recvq_loop_cnt = 0;
uint32_t recvq_call = 0;
#endif

/*
 * Find the next recvq_tq to use.  This routine will go thru all the
 * taskqs until it can dispatch a job for the sctp.  If this fails,
 * it will create a new taskq and try it.
 */
static boolean_t
sctp_find_next_tq(sctp_t *sctp)
{
        int next_tq, try;
        taskq_t *tq;
        sctp_stack_t    *sctps = sctp->sctp_sctps;

        /*
         * Note that since we don't hold a lock on sctp_rq_tq_lock for
         * performance reason, recvq_ta_list_cur_sz can be changed during
         * this loop.  The problem this will create is that the loop may
         * not have tried all the recvq_tq.  This should be OK.
         */
        next_tq = atomic_inc_32_nv(&sctps->sctps_recvq_tq_list_cur) %
            sctps->sctps_recvq_tq_list_cur_sz;
        for (try = 0; try < sctps->sctps_recvq_tq_list_cur_sz; try++) {
                tq = sctps->sctps_recvq_tq_list[next_tq];
                if (taskq_dispatch(tq, sctp_process_recvq, sctp,
                    TQ_NOSLEEP) != (uintptr_t)NULL) {
                        sctp->sctp_recvq_tq = tq;
                        return (B_TRUE);
                }
                next_tq = (next_tq + 1) % sctps->sctps_recvq_tq_list_cur_sz;
        }

        /*
         * Create one more taskq and try it.  Note that sctp_inc_taskq()
         * may not have created another taskq if the number of recvq
         * taskqs is at the maximum.  We are probably in a pretty bad
         * shape if this actually happens...
         */
        sctp_inc_taskq(sctps);
        tq = sctps->sctps_recvq_tq_list[sctps->sctps_recvq_tq_list_cur_sz - 1];
        if (taskq_dispatch(tq, sctp_process_recvq, sctp, TQ_NOSLEEP)
            != (uintptr_t)NULL) {
                sctp->sctp_recvq_tq = tq;
                return (B_TRUE);
        }
        SCTP_KSTAT(sctps, sctp_find_next_tq);
        return (B_FALSE);
}

/*
 * To add a message to the recvq.  Note that the sctp_timer_fire()
 * routine also uses this function to add the timer message to the
 * receive queue for later processing.  And it should be the only
 * caller of sctp_add_recvq() which sets the try_harder argument
 * to B_TRUE.
 *
 * If the try_harder argument is B_TRUE, this routine sctp_find_next_tq()
 * will try very hard to dispatch the task.  Refer to the comment
 * for that routine on how it does that.
 *
 * On failure the message has been freed i.e., this routine always consumes the
 * message. It bumps ipIfStatsInDiscards and and uses ip_drop_input to drop.
 */
void
sctp_add_recvq(sctp_t *sctp, mblk_t *mp, boolean_t caller_hold_lock,
    ip_recv_attr_t *ira)
{
        mblk_t  *attrmp;
        ip_stack_t      *ipst = sctp->sctp_sctps->sctps_netstack->netstack_ip;

        ASSERT(ira->ira_ill == NULL);

        if (!caller_hold_lock)
                mutex_enter(&sctp->sctp_recvq_lock);

        /* If the taskq dispatch has not been scheduled, do it now. */
        if (sctp->sctp_recvq_tq == NULL) {
                ASSERT(sctp->sctp_recvq == NULL);
                if (!sctp_find_next_tq(sctp)) {
                        if (!caller_hold_lock)
                                mutex_exit(&sctp->sctp_recvq_lock);
                        BUMP_MIB(&ipst->ips_ip_mib, ipIfStatsInDiscards);
                        ip_drop_input("ipIfStatsInDiscards", mp, NULL);
                        freemsg(mp);
                        return;
                }
                /* Make sure the sctp_t will not go away. */
                SCTP_REFHOLD(sctp);
        }

        attrmp = ip_recv_attr_to_mblk(ira);
        if (attrmp == NULL) {
                if (!caller_hold_lock)
                        mutex_exit(&sctp->sctp_recvq_lock);
                BUMP_MIB(&ipst->ips_ip_mib, ipIfStatsInDiscards);
                ip_drop_input("ipIfStatsInDiscards", mp, NULL);
                freemsg(mp);
                return;
        }
        ASSERT(attrmp->b_cont == NULL);
        attrmp->b_cont = mp;
        mp = attrmp;

        if (sctp->sctp_recvq == NULL) {
                sctp->sctp_recvq = mp;
                sctp->sctp_recvq_tail = mp;
        } else {
                sctp->sctp_recvq_tail->b_next = mp;
                sctp->sctp_recvq_tail = mp;
        }

        if (!caller_hold_lock)
                mutex_exit(&sctp->sctp_recvq_lock);
}

static void
sctp_process_recvq(void *arg)
{
        sctp_t          *sctp = (sctp_t *)arg;
        mblk_t          *mp;
#ifdef DEBUG
        uint32_t        loop_cnt = 0;
#endif
        ip_recv_attr_t  iras;

#ifdef  _BIG_ENDIAN
#define IPVER(ip6h)     ((((uint32_t *)ip6h)[0] >> 28) & 0x7)
#else
#define IPVER(ip6h)     ((((uint32_t *)ip6h)[0] >> 4) & 0x7)
#endif

        RUN_SCTP(sctp);
        mutex_enter(&sctp->sctp_recvq_lock);

#ifdef DEBUG
        recvq_call++;
#endif
        /*
         * Note that while we are in this loop, other thread can put
         * new packets in the receive queue.  We may be looping for
         * quite a while.
         */
        while ((mp = sctp->sctp_recvq) != NULL) {
                mblk_t *data_mp;

                sctp->sctp_recvq = mp->b_next;
                mutex_exit(&sctp->sctp_recvq_lock);
                mp->b_next = NULL;
#ifdef DEBUG
                loop_cnt++;
#endif
                mp->b_prev = NULL;

                data_mp = mp->b_cont;
                mp->b_cont = NULL;
                if (!ip_recv_attr_from_mblk(mp, &iras)) {
                        ip_drop_input("ip_recv_attr_from_mblk", mp, NULL);
                        freemsg(mp);
                        ira_cleanup(&iras, B_TRUE);
                        continue;
                }

                if (iras.ira_flags & IRAF_ICMP_ERROR)
                        sctp_icmp_error(sctp, data_mp);
                else
                        sctp_input_data(sctp, data_mp, &iras);

                ira_cleanup(&iras, B_TRUE);
                mutex_enter(&sctp->sctp_recvq_lock);
        }

        sctp->sctp_recvq_tail = NULL;
        sctp->sctp_recvq_tq = NULL;

        mutex_exit(&sctp->sctp_recvq_lock);

        WAKE_SCTP(sctp);

#ifdef DEBUG
        if (loop_cnt > recvq_loop_cnt)
                recvq_loop_cnt = loop_cnt;
#endif
        /* Now it can go away. */
        SCTP_REFRELE(sctp);
}

/* ARGSUSED */
static int
sctp_conn_cache_constructor(void *buf, void *cdrarg, int kmflags)
{
        conn_t  *connp = (conn_t *)buf;
        sctp_t  *sctp = (sctp_t *)&connp[1];
        int     cnt;

        bzero(connp, sizeof (conn_t));
        bzero(buf, (char *)&sctp[1] - (char *)buf);

        mutex_init(&sctp->sctp_reflock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&sctp->sctp_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&sctp->sctp_recvq_lock, NULL, MUTEX_DEFAULT, NULL);
        cv_init(&sctp->sctp_cv, NULL, CV_DEFAULT, NULL);
        for (cnt = 0; cnt < SCTP_IPIF_HASH; cnt++) {
                rw_init(&sctp->sctp_saddrs[cnt].ipif_hash_lock, NULL,
                    RW_DEFAULT, NULL);
        }

        mutex_init(&connp->conn_lock, NULL, MUTEX_DEFAULT, NULL);
        cv_init(&connp->conn_cv, NULL, CV_DEFAULT, NULL);
        connp->conn_flags = IPCL_SCTPCONN;
        connp->conn_proto = IPPROTO_SCTP;
        connp->conn_sctp = sctp;
        sctp->sctp_connp = connp;
        rw_init(&connp->conn_ilg_lock, NULL, RW_DEFAULT, NULL);

        connp->conn_ixa = kmem_zalloc(sizeof (ip_xmit_attr_t), kmflags);
        if (connp->conn_ixa == NULL) {
                return (ENOMEM);
        }
        connp->conn_ixa->ixa_refcnt = 1;
        connp->conn_ixa->ixa_protocol = connp->conn_proto;
        connp->conn_ixa->ixa_xmit_hint = CONN_TO_XMIT_HINT(connp);
        return (0);
}

/* ARGSUSED */
static void
sctp_conn_cache_destructor(void *buf, void *cdrarg)
{
        conn_t  *connp = (conn_t *)buf;
        sctp_t  *sctp = (sctp_t *)&connp[1];
        int     cnt;

        ASSERT(sctp->sctp_connp == connp);
        ASSERT(!MUTEX_HELD(&sctp->sctp_lock));
        ASSERT(!MUTEX_HELD(&sctp->sctp_reflock));
        ASSERT(!MUTEX_HELD(&sctp->sctp_recvq_lock));

        ASSERT(sctp->sctp_conn_hash_next == NULL);
        ASSERT(sctp->sctp_conn_hash_prev == NULL);
        ASSERT(sctp->sctp_listen_hash_next == NULL);
        ASSERT(sctp->sctp_listen_hash_prev == NULL);
        ASSERT(sctp->sctp_listen_tfp == NULL);
        ASSERT(sctp->sctp_conn_tfp == NULL);

        ASSERT(sctp->sctp_faddrs == NULL);
        ASSERT(sctp->sctp_nsaddrs == 0);

        ASSERT(sctp->sctp_ulpd == NULL);

        ASSERT(sctp->sctp_lastfaddr == NULL);
        ASSERT(sctp->sctp_primary == NULL);
        ASSERT(sctp->sctp_current == NULL);
        ASSERT(sctp->sctp_lastdata == NULL);

        ASSERT(sctp->sctp_xmit_head == NULL);
        ASSERT(sctp->sctp_xmit_tail == NULL);
        ASSERT(sctp->sctp_xmit_unsent == NULL);
        ASSERT(sctp->sctp_xmit_unsent_tail == NULL);

        ASSERT(sctp->sctp_ostrcntrs == NULL);

        ASSERT(sctp->sctp_sack_info == NULL);
        ASSERT(sctp->sctp_ack_mp == NULL);
        ASSERT(sctp->sctp_instr == NULL);

        ASSERT(sctp->sctp_iphc == NULL);
        ASSERT(sctp->sctp_iphc6 == NULL);
        ASSERT(sctp->sctp_ipha == NULL);
        ASSERT(sctp->sctp_ip6h == NULL);
        ASSERT(sctp->sctp_sctph == NULL);
        ASSERT(sctp->sctp_sctph6 == NULL);

        ASSERT(sctp->sctp_cookie_mp == NULL);

        ASSERT(sctp->sctp_refcnt == 0);
        ASSERT(sctp->sctp_timer_mp == NULL);
        ASSERT(sctp->sctp_connp->conn_ref == 0);
        ASSERT(sctp->sctp_heartbeat_mp == NULL);
        ASSERT(sctp->sctp_ptpbhn == NULL && sctp->sctp_bind_hash == NULL);

        ASSERT(sctp->sctp_shutdown_faddr == NULL);

        ASSERT(sctp->sctp_cxmit_list == NULL);

        ASSERT(sctp->sctp_recvq == NULL);
        ASSERT(sctp->sctp_recvq_tail == NULL);
        ASSERT(sctp->sctp_recvq_tq == NULL);

        /*
         * sctp_pad_mp can be NULL if the memory allocation fails
         * in sctp_init_values() and the conn_t is freed.
         */
        if (sctp->sctp_pad_mp != NULL) {
                freeb(sctp->sctp_pad_mp);
                sctp->sctp_pad_mp = NULL;
        }

        mutex_destroy(&sctp->sctp_reflock);
        mutex_destroy(&sctp->sctp_lock);
        mutex_destroy(&sctp->sctp_recvq_lock);
        cv_destroy(&sctp->sctp_cv);
        for (cnt = 0; cnt < SCTP_IPIF_HASH; cnt++) {
                rw_destroy(&sctp->sctp_saddrs[cnt].ipif_hash_lock);
        }

        mutex_destroy(&connp->conn_lock);
        cv_destroy(&connp->conn_cv);
        rw_destroy(&connp->conn_ilg_lock);

        /* Can be NULL if constructor failed */
        if (connp->conn_ixa != NULL) {
                ASSERT(connp->conn_ixa->ixa_refcnt == 1);
                ASSERT(connp->conn_ixa->ixa_ire == NULL);
                ASSERT(connp->conn_ixa->ixa_nce == NULL);
                ixa_refrele(connp->conn_ixa);
        }
}

static void
sctp_conn_cache_init()
{
        sctp_conn_cache = kmem_cache_create("sctp_conn_cache",
            sizeof (sctp_t) + sizeof (conn_t), 0, sctp_conn_cache_constructor,
            sctp_conn_cache_destructor, sctp_conn_reclaim, NULL, NULL, 0);
}

static void
sctp_conn_cache_fini()
{
        kmem_cache_destroy(sctp_conn_cache);
}

void
sctp_conn_init(conn_t *connp)
{
        ASSERT(connp->conn_flags == IPCL_SCTPCONN);
        connp->conn_rq = connp->conn_wq = NULL;
        connp->conn_ixa->ixa_flags |= IXAF_SET_ULP_CKSUM | IXAF_VERIFY_SOURCE |
            IXAF_VERIFY_PMTU;

        ASSERT(connp->conn_proto == IPPROTO_SCTP);
        ASSERT(connp->conn_ixa->ixa_protocol == connp->conn_proto);
        connp->conn_state_flags |= CONN_INCIPIENT;

        ASSERT(connp->conn_sctp != NULL);

        /*
         * Register sctp_notify to listen to capability changes detected by IP.
         * This upcall is made in the context of the call to conn_ip_output
         * thus it holds whatever locks sctp holds across conn_ip_output.
         */
        connp->conn_ixa->ixa_notify = sctp_notify;
        connp->conn_ixa->ixa_notify_cookie = connp->conn_sctp;
}

static void
sctp_conn_clear(conn_t *connp)
{
        /* Clean up conn_t stuff */
        if (connp->conn_latch != NULL) {
                IPLATCH_REFRELE(connp->conn_latch);
                connp->conn_latch = NULL;
        }
        if (connp->conn_latch_in_policy != NULL) {
                IPPOL_REFRELE(connp->conn_latch_in_policy);
                connp->conn_latch_in_policy = NULL;
        }
        if (connp->conn_latch_in_action != NULL) {
                IPACT_REFRELE(connp->conn_latch_in_action);
                connp->conn_latch_in_action = NULL;
        }
        if (connp->conn_policy != NULL) {
                IPPH_REFRELE(connp->conn_policy, connp->conn_netstack);
                connp->conn_policy = NULL;
        }
        if (connp->conn_ipsec_opt_mp != NULL) {
                freemsg(connp->conn_ipsec_opt_mp);
                connp->conn_ipsec_opt_mp = NULL;
        }
        netstack_rele(connp->conn_netstack);
        connp->conn_netstack = NULL;

        /* Leave conn_ixa and other constructed fields in place */
        ipcl_conn_cleanup(connp);
}