/*
 * Copyright (C) 1995-2003 by Darren Reed.
 *
 * See the IPFILTER.LICENCE file for details on licencing.
 *
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 *
 * Copyright (c) 2014, Joyent, Inc.  All rights reserved.
 */

#if defined(KERNEL) || defined(_KERNEL)
# undef KERNEL
# undef _KERNEL
# define        KERNEL  1
# define        _KERNEL 1
#endif
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/file.h>
#if defined(__NetBSD__) && (NetBSD >= 199905) && !defined(IPFILTER_LKM) && \
    defined(_KERNEL)
# include "opt_ipfilter_log.h"
#endif
#if defined(_KERNEL) && defined(__FreeBSD_version) && \
    (__FreeBSD_version >= 400000) && !defined(KLD_MODULE)
#include "opt_inet6.h"
#endif
#if !defined(_KERNEL) && !defined(__KERNEL__)
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# define _KERNEL
# ifdef __OpenBSD__
struct file;
# endif
# include <sys/uio.h>
# undef _KERNEL
#endif
#if defined(_KERNEL) && (__FreeBSD_version >= 220000)
# include <sys/filio.h>
# include <sys/fcntl.h>
# if (__FreeBSD_version >= 300000) && !defined(IPFILTER_LKM)
#  include "opt_ipfilter.h"
# endif
#else
# include <sys/ioctl.h>
#endif
#include <sys/time.h>
#if !defined(linux)
# include <sys/protosw.h>
#endif
#include <sys/socket.h>
#if defined(_KERNEL)
# include <sys/systm.h>
# if !defined(__SVR4) && !defined(__svr4__)
#  include <sys/mbuf.h>
# endif
#endif
#if defined(__SVR4) || defined(__svr4__)
# include <sys/filio.h>
# include <sys/byteorder.h>
# ifdef _KERNEL
#  include <sys/dditypes.h>
# endif
# include <sys/stream.h>
# include <sys/kmem.h>
#endif

#include <net/if.h>
#ifdef sun
# include <net/af.h>
#endif
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#if !defined(linux)
# include <netinet/ip_var.h>
#endif
#if !defined(__hpux) && !defined(linux)
# include <netinet/tcp_fsm.h>
#endif
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include "netinet/ip_compat.h"
#include <netinet/tcpip.h>
#include "netinet/ip_fil.h"
#include "netinet/ip_nat.h"
#include "netinet/ip_frag.h"
#include "netinet/ip_state.h"
#include "netinet/ip_proxy.h"
#include "netinet/ipf_stack.h"
#ifdef  IPFILTER_SYNC
#include "netinet/ip_sync.h"
#endif
#ifdef  IPFILTER_SCAN
#include "netinet/ip_scan.h"
#endif
#ifdef  USE_INET6
#include <netinet/icmp6.h>
#endif
#if (__FreeBSD_version >= 300000)
# include <sys/malloc.h>
# if defined(_KERNEL) && !defined(IPFILTER_LKM)
#  include <sys/libkern.h>
#  include <sys/systm.h>
# endif
#endif
/* END OF INCLUDES */


#if !defined(lint)
static const char sccsid[] = "@(#)ip_state.c    1.8 6/5/96 (C) 1993-2000 Darren Reed";
static const char rcsid[] = "@(#)$Id: ip_state.c,v 2.186.2.36 2005/08/11 19:58:03 darrenr Exp $";
#endif

#ifdef  USE_INET6
static ipstate_t *fr_checkicmp6matchingstate __P((fr_info_t *));
#endif
static ipstate_t *fr_matchsrcdst __P((fr_info_t *, ipstate_t *, i6addr_t *,
                                      i6addr_t *, tcphdr_t *, u_32_t));
static ipstate_t *fr_checkicmpmatchingstate __P((fr_info_t *));
static int fr_state_flush __P((int, int, ipf_stack_t *));
static ips_stat_t *fr_statetstats __P((ipf_stack_t *));
static int fr_state_remove __P((caddr_t, ipf_stack_t *));
static void fr_ipsmove __P((ipstate_t *, u_int, ipf_stack_t *));
static int fr_tcpstate __P((fr_info_t *, tcphdr_t *, ipstate_t *));
static int fr_tcpoptions __P((fr_info_t *, tcphdr_t *, tcpdata_t *));
static ipstate_t *fr_stclone __P((fr_info_t *, tcphdr_t *, ipstate_t *));
static void fr_fixinisn __P((fr_info_t *, ipstate_t *));
static void fr_fixoutisn __P((fr_info_t *, ipstate_t *));
static void fr_checknewisn __P((fr_info_t *, ipstate_t *));
static int fr_stateiter __P((ipftoken_t *, ipfgeniter_t *, ipf_stack_t *));

int fr_stputent __P((caddr_t, ipf_stack_t *));
int fr_stgetent __P((caddr_t, ipf_stack_t *));

#define ONE_DAY         IPF_TTLVAL(1 * 86400)   /* 1 day */
#define FIVE_DAYS       (5 * ONE_DAY)
#define DOUBLE_HASH(x, ifs)     \
    (((x) + ifs->ifs_ips_seed[(x) % ifs->ifs_fr_statesize]) % ifs->ifs_fr_statesize)


/* ------------------------------------------------------------------------ */
/* Function:    fr_stateinit                                                */
/* Returns:     int - 0 == success, -1 == failure                           */
/* Parameters:  ifs - ipf stack instance                                    */
/*                                                                          */
/* Initialise all the global variables used within the state code.          */
/* This action also includes initiailising locks.                           */
/* ------------------------------------------------------------------------ */
int fr_stateinit(ifs)
ipf_stack_t *ifs;
{
#if defined(NEED_LOCAL_RAND) || !defined(_KERNEL)
        struct timeval tv;
#endif
        int i;

        KMALLOCS(ifs->ifs_ips_table, ipstate_t **,
                 ifs->ifs_fr_statesize * sizeof(ipstate_t *));
        if (ifs->ifs_ips_table == NULL)
                return -1;
        bzero((char *)ifs->ifs_ips_table,
              ifs->ifs_fr_statesize * sizeof(ipstate_t *));

        KMALLOCS(ifs->ifs_ips_seed, u_long *,
                 ifs->ifs_fr_statesize * sizeof(*ifs->ifs_ips_seed));
        if (ifs->ifs_ips_seed == NULL)
                return -2;
#if defined(NEED_LOCAL_RAND) || !defined(_KERNEL)
        tv.tv_sec = 0;
        GETKTIME(&tv);
#endif
        for (i = 0; i < ifs->ifs_fr_statesize; i++) {
                /*
                 * XXX - ips_seed[X] should be a random number of sorts.
                 */
#if !defined(NEED_LOCAL_RAND) && defined(_KERNEL)
                ifs->ifs_ips_seed[i] = ipf_random();
#else
                ifs->ifs_ips_seed[i] = ((u_long)ifs->ifs_ips_seed + i) *
                    ifs->ifs_fr_statesize;
                ifs->ifs_ips_seed[i] += tv.tv_sec;
                ifs->ifs_ips_seed[i] *= (u_long)ifs->ifs_ips_seed;
                ifs->ifs_ips_seed[i] ^= 0x5a5aa5a5;
                ifs->ifs_ips_seed[i] *= ifs->ifs_fr_statemax;
#endif
        }

        /* fill icmp reply type table */
        for (i = 0; i <= ICMP_MAXTYPE; i++)
                icmpreplytype4[i] = -1;
        icmpreplytype4[ICMP_ECHO] = ICMP_ECHOREPLY;
        icmpreplytype4[ICMP_TSTAMP] = ICMP_TSTAMPREPLY;
        icmpreplytype4[ICMP_IREQ] = ICMP_IREQREPLY;
        icmpreplytype4[ICMP_MASKREQ] = ICMP_MASKREPLY;
#ifdef  USE_INET6
        /* fill icmp reply type table */
        for (i = 0; i <= ICMP6_MAXTYPE; i++)
                icmpreplytype6[i] = -1;
        icmpreplytype6[ICMP6_ECHO_REQUEST] = ICMP6_ECHO_REPLY;
        icmpreplytype6[ICMP6_MEMBERSHIP_QUERY] = ICMP6_MEMBERSHIP_REPORT;
        icmpreplytype6[ICMP6_NI_QUERY] = ICMP6_NI_REPLY;
        icmpreplytype6[ND_ROUTER_SOLICIT] = ND_ROUTER_ADVERT;
        icmpreplytype6[ND_NEIGHBOR_SOLICIT] = ND_NEIGHBOR_ADVERT;
#endif

        KMALLOCS(ifs->ifs_ips_stats.iss_bucketlen, u_long *,
                 ifs->ifs_fr_statesize * sizeof(u_long));
        if (ifs->ifs_ips_stats.iss_bucketlen == NULL)
                return -1;
        bzero((char *)ifs->ifs_ips_stats.iss_bucketlen,
              ifs->ifs_fr_statesize * sizeof(u_long));

        if (ifs->ifs_fr_state_maxbucket == 0) {
                for (i = ifs->ifs_fr_statesize; i > 0; i >>= 1)
                        ifs->ifs_fr_state_maxbucket++;
                ifs->ifs_fr_state_maxbucket *= 2;
        }

        fr_sttab_init(ifs->ifs_ips_tqtqb, ifs);
        ifs->ifs_ips_tqtqb[IPF_TCP_NSTATES - 1].ifq_next = &ifs->ifs_ips_udptq;
        ifs->ifs_ips_udptq.ifq_ttl = (u_long)ifs->ifs_fr_udptimeout;
        ifs->ifs_ips_udptq.ifq_ref = 1;
        ifs->ifs_ips_udptq.ifq_head = NULL;
        ifs->ifs_ips_udptq.ifq_tail = &ifs->ifs_ips_udptq.ifq_head;
        MUTEX_INIT(&ifs->ifs_ips_udptq.ifq_lock, "ipftq udp tab");
        ifs->ifs_ips_udptq.ifq_next = &ifs->ifs_ips_udpacktq;
        ifs->ifs_ips_udpacktq.ifq_ttl = (u_long)ifs->ifs_fr_udpacktimeout;
        ifs->ifs_ips_udpacktq.ifq_ref = 1;
        ifs->ifs_ips_udpacktq.ifq_head = NULL;
        ifs->ifs_ips_udpacktq.ifq_tail = &ifs->ifs_ips_udpacktq.ifq_head;
        MUTEX_INIT(&ifs->ifs_ips_udpacktq.ifq_lock, "ipftq udpack tab");
        ifs->ifs_ips_udpacktq.ifq_next = &ifs->ifs_ips_icmptq;
        ifs->ifs_ips_icmptq.ifq_ttl = (u_long)ifs->ifs_fr_icmptimeout;
        ifs->ifs_ips_icmptq.ifq_ref = 1;
        ifs->ifs_ips_icmptq.ifq_head = NULL;
        ifs->ifs_ips_icmptq.ifq_tail = &ifs->ifs_ips_icmptq.ifq_head;
        MUTEX_INIT(&ifs->ifs_ips_icmptq.ifq_lock, "ipftq icmp tab");
        ifs->ifs_ips_icmptq.ifq_next = &ifs->ifs_ips_icmpacktq;
        ifs->ifs_ips_icmpacktq.ifq_ttl = (u_long)ifs->ifs_fr_icmpacktimeout;
        ifs->ifs_ips_icmpacktq.ifq_ref = 1;
        ifs->ifs_ips_icmpacktq.ifq_head = NULL;
        ifs->ifs_ips_icmpacktq.ifq_tail = &ifs->ifs_ips_icmpacktq.ifq_head;
        MUTEX_INIT(&ifs->ifs_ips_icmpacktq.ifq_lock, "ipftq icmpack tab");
        ifs->ifs_ips_icmpacktq.ifq_next = &ifs->ifs_ips_iptq;
        ifs->ifs_ips_iptq.ifq_ttl = (u_long)ifs->ifs_fr_iptimeout;
        ifs->ifs_ips_iptq.ifq_ref = 1;
        ifs->ifs_ips_iptq.ifq_head = NULL;
        ifs->ifs_ips_iptq.ifq_tail = &ifs->ifs_ips_iptq.ifq_head;
        MUTEX_INIT(&ifs->ifs_ips_iptq.ifq_lock, "ipftq ip tab");
        ifs->ifs_ips_iptq.ifq_next = &ifs->ifs_ips_deletetq;
        /* entry's ttl in deletetq is just 1 tick */
        ifs->ifs_ips_deletetq.ifq_ttl = (u_long) 1;
        ifs->ifs_ips_deletetq.ifq_ref = 1;
        ifs->ifs_ips_deletetq.ifq_head = NULL;
        ifs->ifs_ips_deletetq.ifq_tail = &ifs->ifs_ips_deletetq.ifq_head;
        MUTEX_INIT(&ifs->ifs_ips_deletetq.ifq_lock, "state delete queue");
        ifs->ifs_ips_deletetq.ifq_next = NULL;

        RWLOCK_INIT(&ifs->ifs_ipf_state, "ipf IP state rwlock");
        MUTEX_INIT(&ifs->ifs_ipf_stinsert, "ipf state insert mutex");
        ifs->ifs_fr_state_init = 1;

        ifs->ifs_ips_last_force_flush = ifs->ifs_fr_ticks;
        return 0;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stateunload                                              */
/* Returns:     Nil                                                         */
/* Parameters:  ifs - ipf stack instance                                    */
/*                                                                          */
/* Release and destroy any resources acquired or initialised so that        */
/* IPFilter can be unloaded or re-initialised.                              */
/* ------------------------------------------------------------------------ */
void fr_stateunload(ifs)
ipf_stack_t *ifs;
{
        ipftq_t *ifq, *ifqnext;
        ipstate_t *is;

        while ((is = ifs->ifs_ips_list) != NULL)
            (void) fr_delstate(is, 0, ifs);

        /*
         * Proxy timeout queues are not cleaned here because although they
         * exist on the state list, appr_unload is called after fr_stateunload
         * and the proxies actually are responsible for them being created.
         * Should the proxy timeouts have their own list?  There's no real
         * justification as this is the only complicationA
         */
        for (ifq = ifs->ifs_ips_utqe; ifq != NULL; ifq = ifqnext) {
                ifqnext = ifq->ifq_next;
                if (((ifq->ifq_flags & IFQF_PROXY) == 0) &&
                    (fr_deletetimeoutqueue(ifq) == 0))
                        fr_freetimeoutqueue(ifq, ifs);
        }

        ifs->ifs_ips_stats.iss_inuse = 0;
        ifs->ifs_ips_num = 0;

        if (ifs->ifs_fr_state_init == 1) {
                fr_sttab_destroy(ifs->ifs_ips_tqtqb);
                MUTEX_DESTROY(&ifs->ifs_ips_udptq.ifq_lock);
                MUTEX_DESTROY(&ifs->ifs_ips_icmptq.ifq_lock);
                MUTEX_DESTROY(&ifs->ifs_ips_udpacktq.ifq_lock);
                MUTEX_DESTROY(&ifs->ifs_ips_icmpacktq.ifq_lock);
                MUTEX_DESTROY(&ifs->ifs_ips_iptq.ifq_lock);
                MUTEX_DESTROY(&ifs->ifs_ips_deletetq.ifq_lock);
        }

        if (ifs->ifs_ips_table != NULL) {
                KFREES(ifs->ifs_ips_table,
                       ifs->ifs_fr_statesize * sizeof(*ifs->ifs_ips_table));
                ifs->ifs_ips_table = NULL;
        }

        if (ifs->ifs_ips_seed != NULL) {
                KFREES(ifs->ifs_ips_seed,
                       ifs->ifs_fr_statesize * sizeof(*ifs->ifs_ips_seed));
                ifs->ifs_ips_seed = NULL;
        }

        if (ifs->ifs_ips_stats.iss_bucketlen != NULL) {
                KFREES(ifs->ifs_ips_stats.iss_bucketlen,
                       ifs->ifs_fr_statesize * sizeof(u_long));
                ifs->ifs_ips_stats.iss_bucketlen = NULL;
        }

        if (ifs->ifs_fr_state_maxbucket_reset == 1)
                ifs->ifs_fr_state_maxbucket = 0;

        if (ifs->ifs_fr_state_init == 1) {
                ifs->ifs_fr_state_init = 0;
                RW_DESTROY(&ifs->ifs_ipf_state);
                MUTEX_DESTROY(&ifs->ifs_ipf_stinsert);
        }
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_statetstats                                              */
/* Returns:     ips_state_t* - pointer to state stats structure             */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Put all the current numbers and pointers into a single struct and return */
/* a pointer to it.                                                         */
/* ------------------------------------------------------------------------ */
static ips_stat_t *fr_statetstats(ifs)
ipf_stack_t *ifs;
{
        ifs->ifs_ips_stats.iss_active = ifs->ifs_ips_num;
        ifs->ifs_ips_stats.iss_statesize = ifs->ifs_fr_statesize;
        ifs->ifs_ips_stats.iss_statemax = ifs->ifs_fr_statemax;
        ifs->ifs_ips_stats.iss_table = ifs->ifs_ips_table;
        ifs->ifs_ips_stats.iss_list = ifs->ifs_ips_list;
        ifs->ifs_ips_stats.iss_ticks = ifs->ifs_fr_ticks;
        return &ifs->ifs_ips_stats;
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_state_remove                                             */
/* Returns:     int - 0 == success, != 0 == failure                         */
/* Parameters:  data(I) - pointer to state structure to delete from table   */
/*              ifs - ipf stack instance                                    */
/*                                                                          */
/* Search for a state structure that matches the one passed, according to   */
/* the IP addresses and other protocol specific information.                */
/* ------------------------------------------------------------------------ */
static int fr_state_remove(data, ifs)
caddr_t data;
ipf_stack_t *ifs;
{
        ipstate_t *sp, st;
        int error;

        sp = &st;
        error = fr_inobj(data, &st, IPFOBJ_IPSTATE);
        if (error)
                return EFAULT;

        WRITE_ENTER(&ifs->ifs_ipf_state);
        for (sp = ifs->ifs_ips_list; sp; sp = sp->is_next)
                if ((sp->is_p == st.is_p) && (sp->is_v == st.is_v) &&
                    !bcmp((caddr_t)&sp->is_src, (caddr_t)&st.is_src,
                          sizeof(st.is_src)) &&
                    !bcmp((caddr_t)&sp->is_dst, (caddr_t)&st.is_dst,
                          sizeof(st.is_dst)) &&
                    !bcmp((caddr_t)&sp->is_ps, (caddr_t)&st.is_ps,
                          sizeof(st.is_ps))) {
                        (void) fr_delstate(sp, ISL_REMOVE, ifs);
                        RWLOCK_EXIT(&ifs->ifs_ipf_state);
                        return 0;
                }
        RWLOCK_EXIT(&ifs->ifs_ipf_state);
        return ESRCH;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_state_ioctl                                              */
/* Returns:     int - 0 == success, != 0 == failure                         */
/* Parameters:  data(I) - pointer to ioctl data                             */
/*              cmd(I)  - ioctl command integer                             */
/*              mode(I) - file mode bits used with open                     */
/*              uid(I)  - uid of caller                                     */
/*              ctx(I)  - pointer to give the uid context                   */
/*              ifs     - ipf stack instance                                */
/*                                                                          */
/* Processes an ioctl call made to operate on the IP Filter state device.   */
/* ------------------------------------------------------------------------ */
int fr_state_ioctl(data, cmd, mode, uid, ctx, ifs)
caddr_t data;
ioctlcmd_t cmd;
int mode, uid;
void *ctx;
ipf_stack_t *ifs;
{
        int arg, ret, error = 0;

        switch (cmd)
        {
        /*
         * Delete an entry from the state table.
         */
        case SIOCDELST :
                error = fr_state_remove(data, ifs);
                break;
        /*
         * Flush the state table
         */
        case SIOCIPFFL :
                error = BCOPYIN(data, (char *)&arg, sizeof(arg));
                if (error != 0) {
                        error = EFAULT;
                } else {
                        if (VALID_TABLE_FLUSH_OPT(arg)) {
                                WRITE_ENTER(&ifs->ifs_ipf_state);
                                ret = fr_state_flush(arg, 4, ifs);
                                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                                error = BCOPYOUT((char *)&ret, data,
                                                sizeof(ret));
                                if (error != 0)
                                        return EFAULT;
                        } else {
                                error = EINVAL;
                        }
                }
                break;

#ifdef  USE_INET6
        case SIOCIPFL6 :
                error = BCOPYIN(data, (char *)&arg, sizeof(arg));
                if (error != 0) {
                        error = EFAULT;
                } else {
                        if (VALID_TABLE_FLUSH_OPT(arg)) {
                                WRITE_ENTER(&ifs->ifs_ipf_state);
                                ret = fr_state_flush(arg, 6, ifs);
                                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                                error = BCOPYOUT((char *)&ret, data,
                                                sizeof(ret));
                                if (error != 0)
                                        return EFAULT;
                        } else {
                                error = EINVAL;
                        }
                }
                break;
#endif
#ifdef  IPFILTER_LOG
        /*
         * Flush the state log.
         */
        case SIOCIPFFB :
                if (!(mode & FWRITE))
                        error = EPERM;
                else {
                        int tmp;

                        tmp = ipflog_clear(IPL_LOGSTATE, ifs);
                        error = BCOPYOUT((char *)&tmp, data, sizeof(tmp));
                        if (error != 0)
                                error = EFAULT;
                }
                break;
        /*
         * Turn logging of state information on/off.
         */
        case SIOCSETLG :
                if (!(mode & FWRITE)) {
                        error = EPERM;
                } else {
                        error = BCOPYIN((char *)data,
                                        (char *)&ifs->ifs_ipstate_logging,
                                        sizeof(ifs->ifs_ipstate_logging));
                        if (error != 0)
                                error = EFAULT;
                }
                break;
        /*
         * Return the current state of logging.
         */
        case SIOCGETLG :
                error = BCOPYOUT((char *)&ifs->ifs_ipstate_logging,
                                (char *)data,
                                sizeof(ifs->ifs_ipstate_logging));
                if (error != 0)
                        error = EFAULT;
                break;
        /*
         * Return the number of bytes currently waiting to be read.
         */
        case FIONREAD :
                arg = ifs->ifs_iplused[IPL_LOGSTATE]; /* returned in an int */
                error = BCOPYOUT((char *)&arg, data, sizeof(arg));
                if (error != 0)
                        error = EFAULT;
                break;
#endif
        /*
         * Get the current state statistics.
         */
        case SIOCGETFS :
                error = fr_outobj(data, fr_statetstats(ifs), IPFOBJ_STATESTAT);
                break;
        /*
         * Lock/Unlock the state table.  (Locking prevents any changes, which
         * means no packets match).
         */
        case SIOCSTLCK :
                if (!(mode & FWRITE)) {
                        error = EPERM;
                } else {
                        error = fr_lock(data, &ifs->ifs_fr_state_lock);
                }
                break;
        /*
         * Add an entry to the current state table.
         */
        case SIOCSTPUT :
                if (!ifs->ifs_fr_state_lock || !(mode & FWRITE)) {
                        error = EACCES;
                        break;
                }
                error = fr_stputent(data, ifs);
                break;
        /*
         * Get a state table entry.
         */
        case SIOCSTGET :
                if (!ifs->ifs_fr_state_lock) {
                        error = EACCES;
                        break;
                }
                error = fr_stgetent(data, ifs);
                break;

        case SIOCGENITER :
            {
                ipftoken_t *token;
                ipfgeniter_t iter;

                error = fr_inobj(data, &iter, IPFOBJ_GENITER);
                if (error != 0)
                        break;

                token = ipf_findtoken(IPFGENITER_STATE, uid, ctx, ifs);
                if (token != NULL)
                        error = fr_stateiter(token, &iter, ifs);
                else
                        error = ESRCH;
                RWLOCK_EXIT(&ifs->ifs_ipf_tokens);
                break;
            }

        case SIOCIPFDELTOK :
                error = BCOPYIN(data, (char *)&arg, sizeof(arg));
                if (error != 0) {
                        error = EFAULT;
                } else {
                        error = ipf_deltoken(arg, uid, ctx, ifs);
                }
                break;

        default :
                error = EINVAL;
                break;
        }
        return error;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stgetent                                                 */
/* Returns:     int - 0 == success, != 0 == failure                         */
/* Parameters:  data(I) - pointer to state structure to retrieve from table */
/*                                                                          */
/* Copy out state information from the kernel to a user space process.  If  */
/* there is a filter rule associated with the state entry, copy that out    */
/* as well.  The entry to copy out is taken from the value of "ips_next" in */
/* the struct passed in and if not null and not found in the list of current*/
/* state entries, the retrieval fails.                                      */
/* ------------------------------------------------------------------------ */
int fr_stgetent(data, ifs)
caddr_t data;
ipf_stack_t *ifs;
{
        ipstate_t *is, *isn;
        ipstate_save_t ips;
        int error;

        error = fr_inobj(data, &ips, IPFOBJ_STATESAVE);
        if (error)
                return EFAULT;

        isn = ips.ips_next;
        if (isn == NULL) {
                isn = ifs->ifs_ips_list;
                if (isn == NULL) {
                        if (ips.ips_next == NULL)
                                return ENOENT;
                        return 0;
                }
        } else {
                /*
                 * Make sure the pointer we're copying from exists in the
                 * current list of entries.  Security precaution to prevent
                 * copying of random kernel data.
                 */
                for (is = ifs->ifs_ips_list; is; is = is->is_next)
                        if (is == isn)
                                break;
                if (!is)
                        return ESRCH;
        }
        ips.ips_next = isn->is_next;
        bcopy((char *)isn, (char *)&ips.ips_is, sizeof(ips.ips_is));
        ips.ips_rule = isn->is_rule;
        if (isn->is_rule != NULL)
                bcopy((char *)isn->is_rule, (char *)&ips.ips_fr,
                      sizeof(ips.ips_fr));
        error = fr_outobj(data, &ips, IPFOBJ_STATESAVE);
        if (error)
                return EFAULT;
        return 0;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stputent                                                 */
/* Returns:     int - 0 == success, != 0 == failure                         */
/* Parameters:  data(I) - pointer to state information struct               */
/*              ifs     - ipf stack instance                                */
/*                                                                          */
/* This function implements the SIOCSTPUT ioctl: insert a state entry into  */
/* the state table.  If the state info. includes a pointer to a filter rule */
/* then also add in an orphaned rule (will not show up in any "ipfstat -io" */
/* output.                                                                  */
/* ------------------------------------------------------------------------ */
int fr_stputent(data, ifs)
caddr_t data;
ipf_stack_t *ifs;
{
        ipstate_t *is, *isn;
        ipstate_save_t ips;
        int error, i;
        frentry_t *fr;
        char *name;

        error = fr_inobj(data, &ips, IPFOBJ_STATESAVE);
        if (error)
                return EFAULT;

        /*
         * Trigger automatic call to fr_state_flush() if the
         * table has reached capacity specified by hi watermark.
         */
        if (ST_TAB_WATER_LEVEL(ifs) > ifs->ifs_state_flush_level_hi)
                ifs->ifs_fr_state_doflush = 1;

        /*
         * If automatic flushing did not do its job, and the table
         * has filled up, don't try to create a new entry.
         */
        if (ifs->ifs_ips_num >= ifs->ifs_fr_statemax) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_max);
                return ENOMEM;
        }

        KMALLOC(isn, ipstate_t *);
        if (isn == NULL)
                return ENOMEM;

        bcopy((char *)&ips.ips_is, (char *)isn, sizeof(*isn));
        bzero((char *)isn, offsetof(struct ipstate, is_pkts));
        isn->is_sti.tqe_pnext = NULL;
        isn->is_sti.tqe_next = NULL;
        isn->is_sti.tqe_ifq = NULL;
        isn->is_sti.tqe_parent = isn;
        isn->is_ifp[0] = NULL;
        isn->is_ifp[1] = NULL;
        isn->is_ifp[2] = NULL;
        isn->is_ifp[3] = NULL;
        isn->is_sync = NULL;
        fr = ips.ips_rule;

        if (fr == NULL) {
                READ_ENTER(&ifs->ifs_ipf_state);
                fr_stinsert(isn, 0, ifs);
                MUTEX_EXIT(&isn->is_lock);
                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                return 0;
        }

        if (isn->is_flags & SI_NEWFR) {
                KMALLOC(fr, frentry_t *);
                if (fr == NULL) {
                        KFREE(isn);
                        return ENOMEM;
                }
                bcopy((char *)&ips.ips_fr, (char *)fr, sizeof(*fr));
                isn->is_rule = fr;
                ips.ips_is.is_rule = fr;
                MUTEX_NUKE(&fr->fr_lock);
                MUTEX_INIT(&fr->fr_lock, "state filter rule lock");

                /*
                 * Look up all the interface names in the rule.
                 */
                for (i = 0; i < 4; i++) {
                        name = fr->fr_ifnames[i];
                        fr->fr_ifas[i] = fr_resolvenic(name, fr->fr_v, ifs);
                        name = isn->is_ifname[i];
                        isn->is_ifp[i] = fr_resolvenic(name, isn->is_v, ifs);
                }

                fr->fr_ref = 0;
                fr->fr_dsize = 0;
                fr->fr_data = NULL;
                fr->fr_type = FR_T_NONE;

                fr_resolvedest(&fr->fr_tif, fr->fr_v, ifs);
                fr_resolvedest(&fr->fr_dif, fr->fr_v, ifs);
                fr_resolvedest(&fr->fr_rif, fr->fr_v, ifs);

                /*
                 * send a copy back to userland of what we ended up
                 * to allow for verification.
                 */
                error = fr_outobj(data, &ips, IPFOBJ_STATESAVE);
                if (error) {
                        KFREE(isn);
                        MUTEX_DESTROY(&fr->fr_lock);
                        KFREE(fr);
                        return EFAULT;
                }
                READ_ENTER(&ifs->ifs_ipf_state);
                fr_stinsert(isn, 0, ifs);
                MUTEX_EXIT(&isn->is_lock);
                RWLOCK_EXIT(&ifs->ifs_ipf_state);

        } else {
                READ_ENTER(&ifs->ifs_ipf_state);
                for (is = ifs->ifs_ips_list; is; is = is->is_next)
                        if (is->is_rule == fr) {
                                fr_stinsert(isn, 0, ifs);
                                MUTEX_EXIT(&isn->is_lock);
                                break;
                        }

                if (is == NULL) {
                        KFREE(isn);
                        isn = NULL;
                }
                RWLOCK_EXIT(&ifs->ifs_ipf_state);

                return (isn == NULL) ? ESRCH : 0;
        }

        return 0;
}


/* ------------------------------------------------------------------------ */
/* Function:   fr_stinsert                                                  */
/* Returns:    Nil                                                          */
/* Parameters: is(I)  - pointer to state structure                          */
/*             rev(I) - flag indicating forward/reverse direction of packet */
/*                                                                          */
/* Inserts a state structure into the hash table (for lookups) and the list */
/* of state entries (for enumeration).  Resolves all of the interface names */
/* to pointers and adjusts running stats for the hash table as appropriate. */
/*                                                                          */
/* Locking: it is assumed that some kind of lock on ipf_state is held.      */
/*          Exits with is_lock initialised and held.                        */
/* ------------------------------------------------------------------------ */
void fr_stinsert(is, rev, ifs)
ipstate_t *is;
int rev;
ipf_stack_t *ifs;
{
        frentry_t *fr;
        u_int hv;
        int i;

        MUTEX_INIT(&is->is_lock, "ipf state entry");

        fr = is->is_rule;
        if (fr != NULL) {
                MUTEX_ENTER(&fr->fr_lock);
                fr->fr_ref++;
                fr->fr_statecnt++;
                MUTEX_EXIT(&fr->fr_lock);
        }

        /*
         * Look up all the interface names in the state entry.
         */
        for (i = 0; i < 4; i++) {
                if (is->is_ifp[i] != NULL)
                        continue;
                is->is_ifp[i] = fr_resolvenic(is->is_ifname[i], is->is_v, ifs);
        }

        /*
         * If we could trust is_hv, then the modulous would not be needed, but
         * when running with IPFILTER_SYNC, this stops bad values.
         */
        hv = is->is_hv % ifs->ifs_fr_statesize;
        is->is_hv = hv;

        /*
         * We need to get both of these locks...the first because it is
         * possible that once the insert is complete another packet might
         * come along, match the entry and want to update it.
         */
        MUTEX_ENTER(&is->is_lock);
        MUTEX_ENTER(&ifs->ifs_ipf_stinsert);

        /*
         * add into list table.
         */
        if (ifs->ifs_ips_list != NULL)
                ifs->ifs_ips_list->is_pnext = &is->is_next;
        is->is_pnext = &ifs->ifs_ips_list;
        is->is_next = ifs->ifs_ips_list;
        ifs->ifs_ips_list = is;

        if (ifs->ifs_ips_table[hv] != NULL)
                ifs->ifs_ips_table[hv]->is_phnext = &is->is_hnext;
        else
                ifs->ifs_ips_stats.iss_inuse++;
        is->is_phnext = ifs->ifs_ips_table + hv;
        is->is_hnext = ifs->ifs_ips_table[hv];
        ifs->ifs_ips_table[hv] = is;
        ifs->ifs_ips_stats.iss_bucketlen[hv]++;
        ifs->ifs_ips_num++;
        MUTEX_EXIT(&ifs->ifs_ipf_stinsert);

        fr_setstatequeue(is, rev, ifs);
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_match_ipv4addrs                                          */
/* Returns:     int -   2 strong match (same addresses, same direction)     */
/*                      1 weak match (same address, opposite direction)     */
/*                      0 no match                                          */
/*                                                                          */
/* Function matches IPv4 addresses.                                         */
/* ------------------------------------------------------------------------ */
static int fr_match_ipv4addrs(is1, is2)
ipstate_t *is1;
ipstate_t *is2;
{
        int     rv;

        if (is1->is_saddr == is2->is_saddr && is1->is_daddr == is2->is_daddr)
                rv = 2;
        else if (is1->is_saddr == is2->is_daddr &&
            is1->is_daddr == is2->is_saddr)
                rv = 1;
        else
                rv = 0;

        return (rv);
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_match_ipv6addrs                                          */
/* Returns:     int -   2 strong match (same addresses, same direction)     */
/*                      1 weak match (same addresses, opposite direction)   */
/*                      0 no match                                          */
/*                                                                          */
/* Function matches IPv6 addresses.                                         */
/* ------------------------------------------------------------------------ */
static int fr_match_ipv6addrs(is1, is2)
ipstate_t *is1;
ipstate_t *is2;
{
        int     rv;

        if (IP6_EQ(&is1->is_src, &is2->is_src) &&
            IP6_EQ(&is1->is_dst, &is2->is_dst))
                rv = 2;
        else if (IP6_EQ(&is1->is_src, &is2->is_dst) &&
            IP6_EQ(&is1->is_dst, &is2->is_src)) {
                rv = 1;
        }
        else
                rv = 0;

        return (rv);
}
/* ------------------------------------------------------------------------ */
/* Function:    fr_match_addresses                                          */
/* Returns:     int -   2 strong match (same addresses, same direction)     */
/*                      1 weak match (same address, opposite directions)    */
/*                      0 no match                                          */
/* Parameters:  is1, is2 pointers to states we are checking                 */
/*                                                                          */
/* Matches addresses, function uses fr_match_ipvXaddrs() to deal with IPv4  */
/* and IPv6 address format.                                                 */
/* ------------------------------------------------------------------------ */
static int fr_match_addresses(is1, is2)
ipstate_t *is1;
ipstate_t *is2;
{
        int     rv;

        if (is1->is_v == 4) {
                rv = fr_match_ipv4addrs(is1, is2);
        } else {
                rv = fr_match_ipv6addrs(is1, is2);
        }

        return (rv);
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_match_ppairs                                             */
/* Returns:     int -   2 strong match (same ports, same direction)         */
/*                      1 weak match (same ports, different direction)      */
/*                      0 no match                                          */
/* Parameters   ppairs1, ppairs - src, dst ports we want to match.          */
/*                                                                          */
/* Matches two port_pair_t types (port pairs). Each port pair contains      */
/* src, dst port, which belong to session (state entry).                    */
/* ------------------------------------------------------------------------ */
static int fr_match_ppairs(ppairs1, ppairs2)
port_pair_t *ppairs1;
port_pair_t *ppairs2;
{
        int     rv;

        if (ppairs1->pp_sport == ppairs2->pp_sport &&
            ppairs1->pp_dport == ppairs2->pp_dport)
                rv = 2;
        else if (ppairs1->pp_sport == ppairs2->pp_dport &&
                    ppairs1->pp_dport == ppairs2->pp_sport)
                rv = 1;
        else
                rv = 0;

        return (rv);
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_match_l4_hdr                                             */
/* Returns:     int -   0 no match,                                         */
/*                      1 weak match (same ports, different directions)     */
/*                      2 strong match (same ports, same direction)         */
/* Parameters   is1, is2 - states we want to match                          */
/*                                                                          */
/* Function matches L4 header data (source ports for TCP, UDP, CallIds for  */
/* GRE protocol).                                                           */
/* ------------------------------------------------------------------------ */
static int fr_match_l4_hdr(is1, is2)
ipstate_t *is1;
ipstate_t *is2;
{
        int     rv = 0;
        port_pair_t     pp1;
        port_pair_t     pp2;

        if (is1->is_p != is2->is_p)
                return (0);

        switch (is1->is_p) {
                case    IPPROTO_TCP:
                        pp1.pp_sport = is1->is_ps.is_ts.ts_sport;
                        pp1.pp_dport = is1->is_ps.is_ts.ts_dport;
                        pp2.pp_sport = is2->is_ps.is_ts.ts_sport;
                        pp2.pp_dport = is2->is_ps.is_ts.ts_dport;
                        rv = fr_match_ppairs(&pp1, &pp2);
                        break;
                case    IPPROTO_UDP:
                        pp1.pp_sport = is1->is_ps.is_us.us_sport;
                        pp1.pp_dport = is1->is_ps.is_us.us_dport;
                        pp2.pp_sport = is2->is_ps.is_us.us_sport;
                        pp2.pp_dport = is2->is_ps.is_us.us_dport;
                        rv = fr_match_ppairs(&pp1, &pp2);
                        break;
                case    IPPROTO_GRE:
                        /* greinfo_t can be also interprted as port pair */
                        pp1.pp_sport = is1->is_ps.is_ug.gs_call[0];
                        pp1.pp_dport = is1->is_ps.is_ug.gs_call[1];
                        pp2.pp_sport = is2->is_ps.is_ug.gs_call[0];
                        pp2.pp_dport = is2->is_ps.is_ug.gs_call[1];
                        rv = fr_match_ppairs(&pp1, &pp2);
                        break;
                case    IPPROTO_ICMP:
                case    IPPROTO_ICMPV6:
                        if (bcmp(&is1->is_ps, &is2->is_ps, sizeof (icmpinfo_t)))
                                rv = 1;
                        else
                                rv = 0;
                        break;
                default:
                        rv = 0;
        }

        return (rv);
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_matchstates                                              */
/* Returns:     int - nonzero match, zero no match                          */
/* Parameters   is1, is2 - states we want to match                          */
/*                                                                          */
/* The state entries are equal (identical match) if they belong to the same */
/* session. Any time new state entry is being added the fr_addstate()       */
/* function creates temporal state entry from the data it gets from IP and  */
/* L4 header. The fr_matchstats() must be also aware of packet direction,   */
/* which is also stored within the state entry. We should keep in mind the  */
/* information about packet direction is spread accross L3 (addresses) and  */
/* L4 (ports). There are three possible relationships betwee is1, is2:      */
/*              - no match (match(is1, is2) == 0))                          */
/*              - weak match same addresses (ports), but different          */
/*                      directions (1)  (fr_match_xxxx(is1, is2) == 1)      */
/*              - strong match same addresses (ports) and same directions   */
/*                       (2) (fr_match_xxxx(is1, is2) == 2)                 */
/*                                                                          */
/* There are functions, which match match addresses (L3 header) in is1, is2 */
/* and functions, which are used to compare ports (L4 header) data. We say  */
/* the is1 and is2 are same (identical) if there is a match                 */
/* (fr_match_l4_hdr(is1, is2) != 0) and matchlevels are same for entries    */
/* (fr_match_l3_hdr(is1, is2) == fr_match_l4_hdr(is1, is2)) for is1, is2.   */
/* Such requirement deals with case as follows:                             */
/*      suppose there are two connections between hosts A, B. Connection 1: */
/*                      a.a.a.a:12345 <=> b.b.b.b:54321                     */
/*              Connection 2:                                               */
/*                      a.a.a.a:54321 <=> b.b.b.b:12345                     */
/* since we've introduced match levels into our fr_matchstates(), we are    */
/* able to identify, which packets belong to connection A and which belong  */
/* to connection B.     Assume there are two entries is1, is2. is1 has been */
/* from con. 1 packet, which travelled from A to B:                         */
/*                      a.a.a.a:12345 -> b.b.b.b:54321                      */
/* while s2, has been created from packet which belongs to con. 2 and is    */
/* also coming from A to B:                                                 */
/*                      a.a.a.a:54321 -> b.b.b.b:12345                      */
/* fr_match_l3_hdr(is1, is2) == 2 -> strong match, while                    */
/* fr_match_l4_hdr(is1, is2) == 1 -> weak match. Since match levels are     */
/* different the state entries are not identical -> no match as a final     */
/* result.                                                                  */
/* ------------------------------------------------------------------------ */
static int fr_matchstates(is1, is2)
ipstate_t *is1;
ipstate_t *is2;
{
        int     rv;
        int     amatch;
        int     pmatch;

        if (bcmp(&is1->is_pass, &is2->is_pass,
                offsetof(struct ipstate, is_ps) -
                offsetof(struct ipstate, is_pass)) == 0) {

                pmatch = fr_match_l4_hdr(is1, is2);
                amatch = fr_match_addresses(is1, is2);
                /*
                 * If addresses match (amatch != 0), then 'match levels'
                 * must be same for matching entries. If amatch and pmatch
                 * have different values (different match levels), then
                 * is1 and is2 belong to different sessions.
                 */
                rv = (amatch != 0) && (amatch == pmatch);
        }
        else
                rv = 0;

        return (rv);
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_addstate                                                 */
/* Returns:     ipstate_t* - NULL == failure, else pointer to new state     */
/* Parameters:  fin(I)    - pointer to packet information                   */
/*              stsave(O) - pointer to place to save pointer to created     */
/*                          state structure.                                */
/*              flags(I)  - flags to use when creating the structure        */
/*                                                                          */
/* Creates a new IP state structure from the packet information collected.  */
/* Inserts it into the state table and appends to the bottom of the active  */
/* list.  If the capacity of the table has reached the maximum allowed then */
/* the call will fail and a flush is scheduled for the next timeout call.   */
/* ------------------------------------------------------------------------ */
ipstate_t *fr_addstate(fin, stsave, flags)
fr_info_t *fin;
ipstate_t **stsave;
u_int flags;
{
        ipstate_t *is, ips;
        struct icmp *ic;
        u_int pass, hv;
        frentry_t *fr;
        tcphdr_t *tcp;
        grehdr_t *gre;
        void *ifp;
        int out;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_state_lock ||
            (fin->fin_flx & (FI_SHORT|FI_STATE|FI_FRAGBODY|FI_BAD)))
                return NULL;

        if ((fin->fin_flx & FI_OOW) && !(fin->fin_tcpf & TH_SYN))
                return NULL;

        /*
         * Trigger automatic call to fr_state_flush() if the
         * table has reached capacity specified by hi watermark.
         */
        if (ST_TAB_WATER_LEVEL(ifs) > ifs->ifs_state_flush_level_hi)
                ifs->ifs_fr_state_doflush = 1;

        /*
         * If the max number of state entries has been reached, and there is no
         * limit on the state count for the rule, then do not continue.  In the
         * case where a limit exists, it's ok allow the entries to be created as
         * long as specified limit itself has not been reached.
         *
         * Note that because the lock isn't held on fr, it is possible to exceed
         * the specified size of the table.  However, the cost of this is being
         * ignored here; as the number by which it can go over is a product of
         * the number of simultaneous threads that could be executing in here.
         * So, a limit of 100 won't result in 200, but could result in 101 or 102.
         *
         * Also note that, since the automatic flush should have been triggered
         * well before we reach the maximum number of state table entries, the
         * likelihood of reaching the max (and thus exceedng it) is minimal.
         */
        fr = fin->fin_fr;
        if (fr != NULL) {
                if ((ifs->ifs_ips_num >= ifs->ifs_fr_statemax) &&
                    (fr->fr_statemax == 0)) {
                        ATOMIC_INCL(ifs->ifs_ips_stats.iss_max);
                        return NULL;
                }
                if ((fr->fr_statemax != 0) &&
                    (fr->fr_statecnt >= fr->fr_statemax)) {
                        ATOMIC_INCL(ifs->ifs_ips_stats.iss_maxref);
                        ifs->ifs_fr_state_doflush = 1;
                        return NULL;
                }
        }

        ic = NULL;
        tcp = NULL;
        out = fin->fin_out;
        is = &ips;
        bzero((char *)is, sizeof(*is));

        if (fr == NULL) {
                pass = ifs->ifs_fr_flags;
                is->is_tag = FR_NOLOGTAG;
        } else {
                pass = fr->fr_flags;
        }

        is->is_die = 1 + ifs->ifs_fr_ticks;
        /*
         * We want to check everything that is a property of this packet,
         * but we don't (automatically) care about it's fragment status as
         * this may change.
         */
        is->is_pass = pass;
        is->is_v = fin->fin_v;
        is->is_opt[0] = fin->fin_optmsk;
        is->is_optmsk[0] = 0xffffffff;
        /*
         * The reverse direction option mask will be set in fr_matchsrcdst(),
         * when we will see the first packet from the peer. We will leave it
         * as zero for now.
         */
        is->is_optmsk[1] = 0x0;

        if (is->is_v == 6) {
                is->is_opt[0] &= ~0x8;
                is->is_optmsk[0] &= ~0x8;
        }
        is->is_sec = fin->fin_secmsk;
        is->is_secmsk = 0xffff;
        is->is_auth = fin->fin_auth;
        is->is_authmsk = 0xffff;

        /*
         * Copy and calculate...
         */
        hv = (is->is_p = fin->fin_fi.fi_p);
        is->is_src = fin->fin_fi.fi_src;
        hv += is->is_saddr;
        is->is_dst = fin->fin_fi.fi_dst;
        hv += is->is_daddr;
#ifdef  USE_INET6
        if (fin->fin_v == 6) {
                /*
                 * For ICMPv6, we check to see if the destination address is
                 * a multicast address.  If it is, do not include it in the
                 * calculation of the hash because the correct reply will come
                 * back from a real address, not a multicast address.
                 */
                if ((is->is_p == IPPROTO_ICMPV6) &&
                    IN6_IS_ADDR_MULTICAST(&is->is_dst.in6)) {
                        /*
                         * So you can do keep state with neighbour discovery.
                         *
                         * Here we could use the address from the neighbour
                         * solicit message to put in the state structure and
                         * we could use that without a wildcard flag too...
                         */
                        is->is_flags |= SI_W_DADDR;
                        hv -= is->is_daddr;
                } else {
                        hv += is->is_dst.i6[1];
                        hv += is->is_dst.i6[2];
                        hv += is->is_dst.i6[3];
                }
                hv += is->is_src.i6[1];
                hv += is->is_src.i6[2];
                hv += is->is_src.i6[3];
        }
#endif
        if ((fin->fin_v == 4) &&
            (fin->fin_flx & (FI_MULTICAST|FI_BROADCAST|FI_MBCAST))) {
                if (fin->fin_out == 0) {
                        flags |= SI_W_DADDR|SI_CLONE;
                        hv -= is->is_daddr;
                } else {
                        flags |= SI_W_SADDR|SI_CLONE;
                        hv -= is->is_saddr;
                }
        }

        switch (is->is_p)
        {
#ifdef  USE_INET6
        case IPPROTO_ICMPV6 :
                ic = fin->fin_dp;

                switch (ic->icmp_type)
                {
                case ICMP6_ECHO_REQUEST :
                        is->is_icmp.ici_type = ic->icmp_type;
                        hv += (is->is_icmp.ici_id = ic->icmp_id);
                        break;
                case ICMP6_MEMBERSHIP_QUERY :
                case ND_ROUTER_SOLICIT :
                case ND_NEIGHBOR_SOLICIT :
                case ICMP6_NI_QUERY :
                        is->is_icmp.ici_type = ic->icmp_type;
                        break;
                default :
                        return NULL;
                }
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_icmp);
                break;
#endif
        case IPPROTO_ICMP :
                ic = fin->fin_dp;

                switch (ic->icmp_type)
                {
                case ICMP_ECHO :
                case ICMP_ECHOREPLY :
                case ICMP_TSTAMP :
                case ICMP_IREQ :
                case ICMP_MASKREQ :
                        is->is_icmp.ici_type = ic->icmp_type;
                        hv += (is->is_icmp.ici_id = ic->icmp_id);
                        break;
                default :
                        return NULL;
                }
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_icmp);
                break;

        case IPPROTO_GRE :
                gre = fin->fin_dp;

                is->is_gre.gs_flags = gre->gr_flags;
                is->is_gre.gs_ptype = gre->gr_ptype;
                if (GRE_REV(is->is_gre.gs_flags) == 1) {
                        is->is_call[0] = fin->fin_data[0];
                        is->is_call[1] = fin->fin_data[1];
                }
                break;

        case IPPROTO_TCP :
                tcp = fin->fin_dp;

                if (tcp->th_flags & TH_RST)
                        return NULL;
                /*
                 * The endian of the ports doesn't matter, but the ack and
                 * sequence numbers do as we do mathematics on them later.
                 */
                is->is_sport = htons(fin->fin_data[0]);
                is->is_dport = htons(fin->fin_data[1]);
                if ((flags & (SI_W_DPORT|SI_W_SPORT)) == 0) {
                        hv += is->is_sport;
                        hv += is->is_dport;
                }

                /*
                 * If this is a real packet then initialise fields in the
                 * state information structure from the TCP header information.
                 */

                is->is_maxdwin = 1;
                is->is_maxswin = ntohs(tcp->th_win);
                if (is->is_maxswin == 0)
                        is->is_maxswin = 1;

                if ((fin->fin_flx & FI_IGNORE) == 0) {
                        is->is_send = ntohl(tcp->th_seq) + fin->fin_dlen -
                                      (TCP_OFF(tcp) << 2) +
                                      ((tcp->th_flags & TH_SYN) ? 1 : 0) +
                                      ((tcp->th_flags & TH_FIN) ? 1 : 0);
                        is->is_maxsend = is->is_send;

                        /*
                         * Window scale option is only present in
                         * SYN/SYN-ACK packet.
                         */
                        if ((tcp->th_flags & ~(TH_FIN|TH_ACK|TH_ECNALL)) ==
                            TH_SYN &&
                            (TCP_OFF(tcp) > (sizeof(tcphdr_t) >> 2))) {
                                if (fr_tcpoptions(fin, tcp,
                                        &is->is_tcp.ts_data[0]) == -1) {
                                        fin->fin_flx |= FI_BAD;
                                }
                        }

                        if ((fin->fin_out != 0) && (pass & FR_NEWISN) != 0) {
                                fr_checknewisn(fin, is);
                                fr_fixoutisn(fin, is);
                        }

                        if ((tcp->th_flags & TH_OPENING) == TH_SYN)
                                flags |= IS_TCPFSM;
                        else {
                                is->is_maxdwin = is->is_maxswin * 2;
                                is->is_dend = ntohl(tcp->th_ack);
                                is->is_maxdend = ntohl(tcp->th_ack);
                                is->is_maxdwin *= 2;
                        }
                }

                /*
                 * If we're creating state for a starting connection, start the
                 * timer on it as we'll never see an error if it fails to
                 * connect.
                 */
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_tcp);
                break;

        case IPPROTO_UDP :
                tcp = fin->fin_dp;

                is->is_sport = htons(fin->fin_data[0]);
                is->is_dport = htons(fin->fin_data[1]);
                if ((flags & (SI_W_DPORT|SI_W_SPORT)) == 0) {
                        hv += tcp->th_dport;
                        hv += tcp->th_sport;
                }
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_udp);
                break;

        default :
                break;
        }
        hv = DOUBLE_HASH(hv, ifs);
        is->is_hv = hv;
        is->is_rule = fr;
        is->is_flags = flags & IS_INHERITED;

        /*
         * Look for identical state.
         */
        for (is = ifs->ifs_ips_table[is->is_hv % ifs->ifs_fr_statesize];
             is != NULL;
             is = is->is_hnext) {
                if (fr_matchstates(&ips, is) == 1)
                        break;
        }

        /*
         * we've found a matching state -> state already exists,
         * we are not going to add a duplicate record.
         */
        if (is != NULL)
                return NULL;

        if (ifs->ifs_ips_stats.iss_bucketlen[hv] >= ifs->ifs_fr_state_maxbucket) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_bucketfull);
                return NULL;
        }
        KMALLOC(is, ipstate_t *);
        if (is == NULL) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_nomem);
                return NULL;
        }
        bcopy((char *)&ips, (char *)is, sizeof(*is));
        /*
         * Do not do the modulous here, it is done in fr_stinsert().
         */
        if (fr != NULL) {
                (void) strncpy(is->is_group, fr->fr_group, FR_GROUPLEN);
                if (fr->fr_age[0] != 0) {
                        is->is_tqehead[0] =
                            fr_addtimeoutqueue(&ifs->ifs_ips_utqe,
                                               fr->fr_age[0], ifs);
                        is->is_sti.tqe_flags |= TQE_RULEBASED;
                }
                if (fr->fr_age[1] != 0) {
                        is->is_tqehead[1] =
                            fr_addtimeoutqueue(&ifs->ifs_ips_utqe,
                                               fr->fr_age[1], ifs);
                        is->is_sti.tqe_flags |= TQE_RULEBASED;
                }
                is->is_tag = fr->fr_logtag;

                is->is_ifp[(out << 1) + 1] = fr->fr_ifas[1];
                is->is_ifp[(1 - out) << 1] = fr->fr_ifas[2];
                is->is_ifp[((1 - out) << 1) + 1] = fr->fr_ifas[3];

                if (((ifp = fr->fr_ifas[1]) != NULL) &&
                    (ifp != (void *)-1)) {
                        COPYIFNAME(ifp, is->is_ifname[(out << 1) + 1], fr->fr_v);
                }
                if (((ifp = fr->fr_ifas[2]) != NULL) &&
                    (ifp != (void *)-1)) {
                        COPYIFNAME(ifp, is->is_ifname[(1 - out) << 1], fr->fr_v);
                }
                if (((ifp = fr->fr_ifas[3]) != NULL) &&
                    (ifp != (void *)-1)) {
                        COPYIFNAME(ifp, is->is_ifname[((1 - out) << 1) + 1], fr->fr_v);
                }
        }

        is->is_ifp[out << 1] = fin->fin_ifp;
        if (fin->fin_ifp != NULL) {
                COPYIFNAME(fin->fin_ifp, is->is_ifname[out << 1], fin->fin_v);
        }

        is->is_ref = 1;
        is->is_pkts[0] = 0, is->is_bytes[0] = 0;
        is->is_pkts[1] = 0, is->is_bytes[1] = 0;
        is->is_pkts[2] = 0, is->is_bytes[2] = 0;
        is->is_pkts[3] = 0, is->is_bytes[3] = 0;
        if ((fin->fin_flx & FI_IGNORE) == 0) {
                is->is_pkts[out] = 1;
                is->is_bytes[out] = fin->fin_plen;
                is->is_flx[out][0] = fin->fin_flx & FI_CMP;
                is->is_flx[out][0] &= ~FI_OOW;
        }

        if (pass & FR_STSTRICT)
                is->is_flags |= IS_STRICT;

        if (pass & FR_STATESYNC)
                is->is_flags |= IS_STATESYNC;

        if (flags & (SI_WILDP|SI_WILDA)) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_wild);
        }
        is->is_rulen = fin->fin_rule;


        if (pass & FR_LOGFIRST)
                is->is_pass &= ~(FR_LOGFIRST|FR_LOG);

        READ_ENTER(&ifs->ifs_ipf_state);
        is->is_me = stsave;

        fr_stinsert(is, fin->fin_rev, ifs);

        if (fin->fin_p == IPPROTO_TCP) {
                /*
                * If we're creating state for a starting connection, start the
                * timer on it as we'll never see an error if it fails to
                * connect.
                */
                (void) fr_tcp_age(&is->is_sti, fin, ifs->ifs_ips_tqtqb,
                                  is->is_flags);
                MUTEX_EXIT(&is->is_lock);
#ifdef  IPFILTER_SCAN
                if ((is->is_flags & SI_CLONE) == 0)
                        (void) ipsc_attachis(is);
#endif
        } else {
                MUTEX_EXIT(&is->is_lock);
        }
#ifdef  IPFILTER_SYNC
        if ((is->is_flags & IS_STATESYNC) && ((is->is_flags & SI_CLONE) == 0))
                is->is_sync = ipfsync_new(SMC_STATE, fin, is);
#endif
        if (ifs->ifs_ipstate_logging)
                ipstate_log(is, ISL_NEW, ifs);

        RWLOCK_EXIT(&ifs->ifs_ipf_state);
        fin->fin_rev = IP6_NEQ(&is->is_dst, &fin->fin_daddr);
        fin->fin_flx |= FI_STATE;
        if (fin->fin_flx & FI_FRAG)
                (void) fr_newfrag(fin, pass ^ FR_KEEPSTATE);

        return is;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_tcpoptions                                               */
/* Returns:     int - 1 == packet matches state entry, 0 == it does not     */
/* Parameters:  fin(I) - pointer to packet information                      */
/*              tcp(I) - pointer to TCP packet header                       */
/*              td(I)  - pointer to TCP data held as part of the state      */
/*                                                                          */
/* Look after the TCP header for any options and deal with those that are   */
/* present.  Record details about those that we recogise.                   */
/* ------------------------------------------------------------------------ */
static int fr_tcpoptions(fin, tcp, td)
fr_info_t *fin;
tcphdr_t *tcp;
tcpdata_t *td;
{
        int off, mlen, ol, i, len, retval;
        char buf[64], *s, opt;
        mb_t *m = NULL;

        len = (TCP_OFF(tcp) << 2);
        if (fin->fin_dlen < len)
                return 0;
        len -= sizeof(*tcp);

        off = fin->fin_plen - fin->fin_dlen + sizeof(*tcp) + fin->fin_ipoff;

        m = fin->fin_m;
        mlen = MSGDSIZE(m) - off;
        if (len > mlen) {
                len = mlen;
                retval = 0;
        } else {
                retval = 1;
        }

        COPYDATA(m, off, len, buf);

        for (s = buf; len > 0; ) {
                opt = *s;
                if (opt == TCPOPT_EOL)
                        break;
                else if (opt == TCPOPT_NOP)
                        ol = 1;
                else {
                        if (len < 2)
                                break;
                        ol = (int)*(s + 1);
                        if (ol < 2 || ol > len)
                                break;

                        /*
                         * Extract the TCP options we are interested in out of
                         * the header and store them in the the tcpdata struct.
                         */
                        switch (opt)
                        {
                        case TCPOPT_WINDOW :
                                if (ol == TCPOLEN_WINDOW) {
                                        i = (int)*(s + 2);
                                        if (i > TCP_WSCALE_MAX)
                                                i = TCP_WSCALE_MAX;
                                        else if (i < 0)
                                                i = 0;
                                        td->td_winscale = i;
                                        td->td_winflags |= TCP_WSCALE_SEEN |
                                                            TCP_WSCALE_FIRST;
                                } else
                                        retval = -1;
                                break;
                        case TCPOPT_MAXSEG :
                                /*
                                 * So, if we wanted to set the TCP MAXSEG,
                                 * it should be done here...
                                 */
                                if (ol == TCPOLEN_MAXSEG) {
                                        i = (int)*(s + 2);
                                        i <<= 8;
                                        i += (int)*(s + 3);
                                        td->td_maxseg = i;
                                } else
                                        retval = -1;
                                break;
                        case TCPOPT_SACK_PERMITTED :
                                if (ol == TCPOLEN_SACK_PERMITTED)
                                        td->td_winflags |= TCP_SACK_PERMIT;
                                else
                                        retval = -1;
                                break;
                        }
                }
                len -= ol;
                s += ol;
        }
        return retval;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_tcpstate                                                 */
/* Returns:     int - 1 == packet matches state entry, 0 == it does not     */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              tcp(I)   - pointer to TCP packet header                     */
/*              is(I)  - pointer to master state structure                  */
/*                                                                          */
/* Check to see if a packet with TCP headers fits within the TCP window.    */
/* Change timeout depending on whether new packet is a SYN-ACK returning    */
/* for a SYN or a RST or FIN which indicate time to close up shop.          */
/* ------------------------------------------------------------------------ */
static int fr_tcpstate(fin, tcp, is)
fr_info_t *fin;
tcphdr_t *tcp;
ipstate_t *is;
{
        int source, ret = 0, flags;
        tcpdata_t  *fdata, *tdata;
        ipf_stack_t *ifs = fin->fin_ifs;

        source = !fin->fin_rev;
        if (((is->is_flags & IS_TCPFSM) != 0) && (source == 1) &&
            (ntohs(is->is_sport) != fin->fin_data[0]))
                source = 0;
        fdata = &is->is_tcp.ts_data[!source];
        tdata = &is->is_tcp.ts_data[source];

        MUTEX_ENTER(&is->is_lock);

        /*
         * If a SYN packet is received for a connection that is in a half
         * closed state, then move its state entry to deletetq. In such case
         * the SYN packet will be consequently dropped. This allows new state
         * entry to be created with a retransmited SYN packet.
         */
        if ((tcp->th_flags & TH_OPENING) == TH_SYN) {
                if ((is->is_state[source] > IPF_TCPS_ESTABLISHED) &&
                    (is->is_state[!source] > IPF_TCPS_ESTABLISHED)) {
                        is->is_state[source] = IPF_TCPS_CLOSED;
                        is->is_state[!source] = IPF_TCPS_CLOSED;
                        /*
                         * Do not update is->is_sti.tqe_die in case state entry
                         * is already present in deletetq. It prevents state
                         * entry ttl update by retransmitted SYN packets, which
                         * may arrive before timer tick kicks off. The SYN
                         * packet will be dropped again.
                         */
                        if (is->is_sti.tqe_ifq != &ifs->ifs_ips_deletetq)
                                fr_movequeue(&is->is_sti, is->is_sti.tqe_ifq,
                                        &fin->fin_ifs->ifs_ips_deletetq,
                                        fin->fin_ifs);

                        MUTEX_EXIT(&is->is_lock);
                        return 0;
                }
        }

        if (fr_tcpinwindow(fin, fdata, tdata, tcp, is->is_flags)) {
#ifdef  IPFILTER_SCAN
                if (is->is_flags & (IS_SC_CLIENT|IS_SC_SERVER)) {
                        ipsc_packet(fin, is);
                        if (FR_ISBLOCK(is->is_pass)) {
                                MUTEX_EXIT(&is->is_lock);
                                return 1;
                        }
                }
#endif

                /*
                 * Nearing end of connection, start timeout.
                 */
                ret = fr_tcp_age(&is->is_sti, fin, ifs->ifs_ips_tqtqb,
                                 is->is_flags);
                if (ret == 0) {
                        MUTEX_EXIT(&is->is_lock);
                        return 0;
                }

                /*
                 * set s0's as appropriate.  Use syn-ack packet as it
                 * contains both pieces of required information.
                 */
                /*
                 * Window scale option is only present in SYN/SYN-ACK packet.
                 * Compare with ~TH_FIN to mask out T/TCP setups.
                 */
                flags = tcp->th_flags & ~(TH_FIN|TH_ECNALL);
                if (flags == (TH_SYN|TH_ACK)) {
                        is->is_s0[source] = ntohl(tcp->th_ack);
                        is->is_s0[!source] = ntohl(tcp->th_seq) + 1;
                        if (TCP_OFF(tcp) > (sizeof (tcphdr_t) >> 2)) {
                                (void) fr_tcpoptions(fin, tcp, fdata);
                        }
                        if ((fin->fin_out != 0) && (is->is_pass & FR_NEWISN))
                                fr_checknewisn(fin, is);
                } else if (flags == TH_SYN) {
                        is->is_s0[source] = ntohl(tcp->th_seq) + 1;
                        if ((TCP_OFF(tcp) > (sizeof(tcphdr_t) >> 2)))
                                (void) fr_tcpoptions(fin, tcp, fdata);

                        if ((fin->fin_out != 0) && (is->is_pass & FR_NEWISN))
                                fr_checknewisn(fin, is);

                }
                ret = 1;
        } else
                fin->fin_flx |= FI_OOW;
        MUTEX_EXIT(&is->is_lock);
        return ret;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_checknewisn                                              */
/* Returns:     Nil                                                         */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              is(I)  - pointer to master state structure                  */
/*                                                                          */
/* Check to see if this TCP connection is expecting and needs a new         */
/* sequence number for a particular direction of the connection.            */
/*                                                                          */
/* NOTE: This does not actually change the sequence numbers, only gets new  */
/* one ready.                                                               */
/* ------------------------------------------------------------------------ */
static void fr_checknewisn(fin, is)
fr_info_t *fin;
ipstate_t *is;
{
        u_32_t sumd, old, new;
        tcphdr_t *tcp;
        int i;

        i = fin->fin_rev;
        tcp = fin->fin_dp;

        if (((i == 0) && !(is->is_flags & IS_ISNSYN)) ||
            ((i == 1) && !(is->is_flags & IS_ISNACK))) {
                old = ntohl(tcp->th_seq);
                new = fr_newisn(fin);
                is->is_isninc[i] = new - old;
                CALC_SUMD(old, new, sumd);
                is->is_sumd[i] = (sumd & 0xffff) + (sumd >> 16);

                is->is_flags |= ((i == 0) ? IS_ISNSYN : IS_ISNACK);
        }
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_tcpinwindow                                              */
/* Returns:     int - 1 == packet inside TCP "window", 0 == not inside.     */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              fdata(I) - pointer to tcp state informatio (forward)        */
/*              tdata(I) - pointer to tcp state informatio (reverse)        */
/*              tcp(I)   - pointer to TCP packet header                     */
/*                                                                          */
/* Given a packet has matched addresses and ports, check to see if it is    */
/* within the TCP data window.  In a show of generosity, allow packets that */
/* are within the window space behind the current sequence # as well.       */
/* ------------------------------------------------------------------------ */
int fr_tcpinwindow(fin, fdata, tdata, tcp, flags)
fr_info_t *fin;
tcpdata_t  *fdata, *tdata;
tcphdr_t *tcp;
int flags;
{
        tcp_seq seq, ack, end;
        int ackskew, tcpflags;
        u_32_t win, maxwin;
        int dsize, inseq;

        /*
         * Find difference between last checked packet and this packet.
         */
        tcpflags = tcp->th_flags;
        seq = ntohl(tcp->th_seq);
        ack = ntohl(tcp->th_ack);

        if (tcpflags & TH_SYN)
                win = ntohs(tcp->th_win);
        else
                win = ntohs(tcp->th_win) << fdata->td_winscale;

        /*
         * win 0 means the receiving endpoint has closed the window, because it
         * has not enough memory to receive data from sender. In such case we
         * are pretending window size to be 1 to let TCP probe data through.
         * TCP probe data can be either 0 or 1 octet of data, the RFC does not
         * state this accurately, so we have to allow 1 octet (win = 1) even if
         * the window is closed (win == 0).
         */
        if (win == 0)
                win = 1;

        dsize = fin->fin_dlen - (TCP_OFF(tcp) << 2) +
                ((tcpflags & TH_SYN) ? 1 : 0) + ((tcpflags & TH_FIN) ? 1 : 0);

        /*
         * if window scaling is present, the scaling is only allowed
         * for windows not in the first SYN packet. In that packet the
         * window is 65535 to specify the largest window possible
         * for receivers not implementing the window scale option.
         * Currently, we do not assume TTCP here. That means that
         * if we see a second packet from a host (after the initial
         * SYN), we can assume that the receiver of the SYN did
         * already send back the SYN/ACK (and thus that we know if
         * the receiver also does window scaling)
         */
        if (!(tcpflags & TH_SYN) && (fdata->td_winflags & TCP_WSCALE_FIRST)) {
                fdata->td_winflags &= ~TCP_WSCALE_FIRST;
                fdata->td_maxwin = win;
        }

        end = seq + dsize;

        if ((fdata->td_end == 0) &&
            (!(flags & IS_TCPFSM) ||
             ((tcpflags & TH_OPENING) == TH_OPENING))) {
                /*
                 * Must be a (outgoing) SYN-ACK in reply to a SYN.
                 */
                fdata->td_end = end - 1;
                fdata->td_maxwin = 1;
                fdata->td_maxend = end + win;
        }

        if (!(tcpflags & TH_ACK)) {  /* Pretend an ack was sent */
                ack = tdata->td_end;
        } else if (((tcpflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) &&
                   (ack == 0)) {
                /* gross hack to get around certain broken tcp stacks */
                ack = tdata->td_end;
        }

        maxwin = tdata->td_maxwin;
        ackskew = tdata->td_end - ack;

        /*
         * Strict sequencing only allows in-order delivery.
         */
        if ((flags & IS_STRICT) != 0) {
                if (seq != fdata->td_end) {
                        DTRACE_PROBE(strict_check);
                        return 0;
                }
        }

#define SEQ_GE(a,b)     ((int)((a) - (b)) >= 0)
#define SEQ_GT(a,b)     ((int)((a) - (b)) > 0)
        inseq = 0;
        DTRACE_PROBE4(
                dyn_params,
                int, dsize,
                int, ackskew,
                int, maxwin,
                int, win
        );
        if (
#if defined(_KERNEL)
                /*
                 * end <-> s + n
                 * maxend <-> ack + win
                 * this is upperbound check
                 */
            (SEQ_GE(fdata->td_maxend, end)) &&
                /*
                 * this is lowerbound check
                 */
            (SEQ_GE(seq, fdata->td_end - maxwin)) &&
#endif
/* XXX what about big packets */
#define MAXACKWINDOW 66000
            (-ackskew <= (MAXACKWINDOW)) &&
            ( ackskew <= (MAXACKWINDOW << fdata->td_winscale))) {
                inseq = 1;
        /*
         * Microsoft Windows will send the next packet to the right of the
         * window if SACK is in use.
         */
        } else if ((seq == fdata->td_maxend) && (ackskew == 0) &&
            (fdata->td_winflags & TCP_SACK_PERMIT) &&
            (tdata->td_winflags & TCP_SACK_PERMIT)) {
                inseq = 1;
        /*
         * RST ACK with SEQ equal to 0 is sent by some OSes (i.e. Solaris) as a
         * response to initial SYN packet, when  there is no application
         * listeing to on a port, where the SYN packet has came to.
         */
        } else if ((seq == 0) && (tcpflags == (TH_RST|TH_ACK)) &&
                        (ackskew >= -1) && (ackskew <= 1)) {
                inseq = 1;
        } else if (!(flags & IS_TCPFSM)) {

                if (!(fdata->td_winflags &
                            (TCP_WSCALE_SEEN|TCP_WSCALE_FIRST))) {
                        /*
                         * No TCPFSM and no window scaling, so make some
                         * extra guesses.
                         */
                        if ((seq == fdata->td_maxend) && (ackskew == 0))
                                inseq = 1;
                        else if (SEQ_GE(seq + maxwin, fdata->td_end - maxwin))
                                inseq = 1;
                }
        }

        if (inseq) {
                /* if ackskew < 0 then this should be due to fragmented
                 * packets. There is no way to know the length of the
                 * total packet in advance.
                 * We do know the total length from the fragment cache though.
                 * Note however that there might be more sessions with
                 * exactly the same source and destination parameters in the
                 * state cache (and source and destination is the only stuff
                 * that is saved in the fragment cache). Note further that
                 * some TCP connections in the state cache are hashed with
                 * sport and dport as well which makes it not worthwhile to
                 * look for them.
                 * Thus, when ackskew is negative but still seems to belong
                 * to this session, we bump up the destinations end value.
                 */
                if (ackskew < 0) {
                        DTRACE_PROBE2(end_update_td,
                                int, tdata->td_end,
                                int, ack
                        );
                        tdata->td_end = ack;
                }

                /* update max window seen */
                if (fdata->td_maxwin < win) {
                        DTRACE_PROBE2(win_update_fd,
                                int, fdata->td_maxwin,
                                int, win
                        );
                        fdata->td_maxwin = win;
                }

                if (SEQ_GT(end, fdata->td_end)) {
                        DTRACE_PROBE2(end_update_fd,
                                int, fdata->td_end,
                                int, end
                        );
                        fdata->td_end = end;
                }

                if (SEQ_GE(ack + win, tdata->td_maxend)) {
                        DTRACE_PROBE2(max_end_update_td,
                                int, tdata->td_maxend,
                                int, ack + win
                        );
                        tdata->td_maxend = ack + win;
                }

                return 1;
        }
        fin->fin_flx |= FI_OOW;

#if defined(_KERNEL)
        if (!(SEQ_GE(seq, fdata->td_end - maxwin)))
                fin->fin_flx |= FI_NEG_OOW;
#endif

        return 0;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stclone                                                  */
/* Returns:     ipstate_t* - NULL == cloning failed,                        */
/*                           else pointer to new state structure            */
/* Parameters:  fin(I) - pointer to packet information                      */
/*              tcp(I) - pointer to TCP/UDP header                          */
/*              is(I)  - pointer to master state structure                  */
/*                                                                          */
/* Create a "duplcate" state table entry from the master.                   */
/* ------------------------------------------------------------------------ */
static ipstate_t *fr_stclone(fin, tcp, is)
fr_info_t *fin;
tcphdr_t *tcp;
ipstate_t *is;
{
        ipstate_t *clone;
        u_32_t send;
        ipf_stack_t *ifs = fin->fin_ifs;

        /*
         * Trigger automatic call to fr_state_flush() if the
         * table has reached capacity specified by hi watermark.
         */
        if (ST_TAB_WATER_LEVEL(ifs) > ifs->ifs_state_flush_level_hi)
                ifs->ifs_fr_state_doflush = 1;

        /*
         * If automatic flushing did not do its job, and the table
         * has filled up, don't try to create a new entry.  A NULL
         * return will indicate that the cloning has failed.
         */
        if (ifs->ifs_ips_num >= ifs->ifs_fr_statemax) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_max);
                return NULL;
        }

        KMALLOC(clone, ipstate_t *);
        if (clone == NULL)
                return NULL;
        bcopy((char *)is, (char *)clone, sizeof(*clone));

        MUTEX_NUKE(&clone->is_lock);

        clone->is_die = ONE_DAY + ifs->ifs_fr_ticks;
        clone->is_state[0] = 0;
        clone->is_state[1] = 0;
        send = ntohl(tcp->th_seq) + fin->fin_dlen - (TCP_OFF(tcp) << 2) +
                ((tcp->th_flags & TH_SYN) ? 1 : 0) +
                ((tcp->th_flags & TH_FIN) ? 1 : 0);

        if (fin->fin_rev == 1) {
                clone->is_dend = send;
                clone->is_maxdend = send;
                clone->is_send = 0;
                clone->is_maxswin = 1;
                clone->is_maxdwin = ntohs(tcp->th_win);
                if (clone->is_maxdwin == 0)
                        clone->is_maxdwin = 1;
        } else {
                clone->is_send = send;
                clone->is_maxsend = send;
                clone->is_dend = 0;
                clone->is_maxdwin = 1;
                clone->is_maxswin = ntohs(tcp->th_win);
                if (clone->is_maxswin == 0)
                        clone->is_maxswin = 1;
        }

        clone->is_flags &= ~SI_CLONE;
        clone->is_flags |= SI_CLONED;
        fr_stinsert(clone, fin->fin_rev, ifs);
        clone->is_ref = 1;
        if (clone->is_p == IPPROTO_TCP) {
                (void) fr_tcp_age(&clone->is_sti, fin, ifs->ifs_ips_tqtqb,
                                  clone->is_flags);
        }
        MUTEX_EXIT(&clone->is_lock);
#ifdef  IPFILTER_SCAN
        (void) ipsc_attachis(is);
#endif
#ifdef  IPFILTER_SYNC
        if (is->is_flags & IS_STATESYNC)
                clone->is_sync = ipfsync_new(SMC_STATE, fin, clone);
#endif
        return clone;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_matchsrcdst                                              */
/* Returns:     Nil                                                         */
/* Parameters:  fin(I) - pointer to packet information                      */
/*              is(I)  - pointer to state structure                         */
/*              src(I) - pointer to source address                          */
/*              dst(I) - pointer to destination address                     */
/*              tcp(I) - pointer to TCP/UDP header                          */
/*                                                                          */
/* Match a state table entry against an IP packet.  The logic below is that */
/* ret gets set to one if the match succeeds, else remains 0.  If it is     */
/* still 0 after the test. no match.                                        */
/* ------------------------------------------------------------------------ */
static ipstate_t *fr_matchsrcdst(fin, is, src, dst, tcp, cmask)
fr_info_t *fin;
ipstate_t *is;
i6addr_t *src, *dst;
tcphdr_t *tcp;
u_32_t cmask;
{
        int ret = 0, rev, out, flags, flx = 0, idx;
        u_short sp, dp;
        u_32_t cflx;
        void *ifp;
        ipf_stack_t *ifs = fin->fin_ifs;

        rev = IP6_NEQ(&is->is_dst, dst);
        ifp = fin->fin_ifp;
        out = fin->fin_out;
        flags = is->is_flags;
        sp = 0;
        dp = 0;

        if (tcp != NULL) {
                sp = htons(fin->fin_sport);
                dp = ntohs(fin->fin_dport);
        }
        if (!rev) {
                if (tcp != NULL) {
                        if (!(flags & SI_W_SPORT) && (sp != is->is_sport))
                                rev = 1;
                        else if (!(flags & SI_W_DPORT) && (dp != is->is_dport))
                                rev = 1;
                }
        }

        idx = (out << 1) + rev;

        /*
         * If the interface for this 'direction' is set, make sure it matches.
         * An interface name that is not set matches any, as does a name of *.
         */
        if ((is->is_ifp[idx] == NULL &&
            (*is->is_ifname[idx] == '\0' || *is->is_ifname[idx] == '*')) ||
            is->is_ifp[idx] == ifp)
                ret = 1;

        if (ret == 0) {
                DTRACE_PROBE(no_match_on_iface);
                return NULL;
        }
        ret = 0;

        /*
         * Match addresses and ports.
         */
        if (rev == 0) {
                if ((IP6_EQ(&is->is_dst, dst) || (flags & SI_W_DADDR)) &&
                    (IP6_EQ(&is->is_src, src) || (flags & SI_W_SADDR))) {
                        if (tcp) {
                                if ((sp == is->is_sport || flags & SI_W_SPORT)&&
                                    (dp == is->is_dport || flags & SI_W_DPORT))
                                        ret = 1;
                        } else {
                                ret = 1;
                        }
                }
        } else {
                if ((IP6_EQ(&is->is_dst, src) || (flags & SI_W_DADDR)) &&
                    (IP6_EQ(&is->is_src, dst) || (flags & SI_W_SADDR))) {
                        if (tcp) {
                                if ((dp == is->is_sport || flags & SI_W_SPORT)&&
                                    (sp == is->is_dport || flags & SI_W_DPORT))
                                        ret = 1;
                        } else {
                                ret = 1;
                        }
                }
        }

        if (ret == 0) {
                DTRACE_PROBE(no_match_on_addrs);
                return NULL;
        }
        /*
         * Whether or not this should be here, is questionable, but the aim
         * is to get this out of the main line.
         */
        if (tcp == NULL)
                flags = is->is_flags & ~(SI_WILDP|SI_NEWFR|SI_CLONE|SI_CLONED);

        /*
         * Only one of the source or destination address can be flaged as a
         * wildcard.  Fill in the missing address, if set.
         * For IPv6, if the address being copied in is multicast, then
         * don't reset the wild flag - multicast causes it to be set in the
         * first place!
         */
        if ((flags & (SI_W_SADDR|SI_W_DADDR))) {
                fr_ip_t *fi = &fin->fin_fi;

                if ((flags & SI_W_SADDR) != 0) {
                        if (rev == 0) {
#ifdef USE_INET6
                                if (is->is_v == 6 &&
                                    IN6_IS_ADDR_MULTICAST(&fi->fi_src.in6))
                                        /*EMPTY*/;
                                else
#endif
                                {
                                        is->is_src = fi->fi_src;
                                        is->is_flags &= ~SI_W_SADDR;
                                }
                        } else {
#ifdef USE_INET6
                                if (is->is_v == 6 &&
                                    IN6_IS_ADDR_MULTICAST(&fi->fi_dst.in6))
                                        /*EMPTY*/;
                                else
#endif
                                {
                                        is->is_src = fi->fi_dst;
                                        is->is_flags &= ~SI_W_SADDR;
                                }
                        }
                } else if ((flags & SI_W_DADDR) != 0) {
                        if (rev == 0) {
#ifdef USE_INET6
                                if (is->is_v == 6 &&
                                    IN6_IS_ADDR_MULTICAST(&fi->fi_dst.in6))
                                        /*EMPTY*/;
                                else
#endif
                                {
                                        is->is_dst = fi->fi_dst;
                                        is->is_flags &= ~SI_W_DADDR;
                                }
                        } else {
#ifdef USE_INET6
                                if (is->is_v == 6 &&
                                    IN6_IS_ADDR_MULTICAST(&fi->fi_src.in6))
                                        /*EMPTY*/;
                                else
#endif
                                {
                                        is->is_dst = fi->fi_src;
                                        is->is_flags &= ~SI_W_DADDR;
                                }
                        }
                }
                if ((is->is_flags & (SI_WILDA|SI_WILDP)) == 0) {
                        ATOMIC_DECL(ifs->ifs_ips_stats.iss_wild);
                }
        }

        flx = fin->fin_flx & cmask;
        cflx = is->is_flx[out][rev];

        /*
         * Match up any flags set from IP options.
         */
        if ((cflx && (flx != (cflx & cmask))) ||
            ((fin->fin_optmsk & is->is_optmsk[rev]) != is->is_opt[rev]) ||
            ((fin->fin_secmsk & is->is_secmsk) != is->is_sec) ||
            ((fin->fin_auth & is->is_authmsk) != is->is_auth)) {
                DTRACE_PROBE4(no_match_on_flags,
                    int, (cflx && (flx != (cflx & cmask))),
                    int,
                    ((fin->fin_optmsk & is->is_optmsk[rev]) != is->is_opt[rev]),
                    int, ((fin->fin_secmsk & is->is_secmsk) != is->is_sec),
                    int, ((fin->fin_auth & is->is_authmsk) != is->is_auth)
                );
                return NULL;
        }
        /*
         * Only one of the source or destination port can be flagged as a
         * wildcard.  When filling it in, fill in a copy of the matched entry
         * if it has the cloning flag set.
         */
        if ((fin->fin_flx & FI_IGNORE) != 0) {
                fin->fin_rev = rev;
                return is;
        }

        if ((flags & (SI_W_SPORT|SI_W_DPORT))) {
                if ((flags & SI_CLONE) != 0) {
                        ipstate_t *clone;

                        clone = fr_stclone(fin, tcp, is);
                        if (clone == NULL)
                                return NULL;
                        is = clone;
                } else {
                        ATOMIC_DECL(ifs->ifs_ips_stats.iss_wild);
                }

                if ((flags & SI_W_SPORT) != 0) {
                        if (rev == 0) {
                                is->is_sport = sp;
                                is->is_send = ntohl(tcp->th_seq);
                        } else {
                                is->is_sport = dp;
                                is->is_send = ntohl(tcp->th_ack);
                        }
                        is->is_maxsend = is->is_send + 1;
                } else if ((flags & SI_W_DPORT) != 0) {
                        if (rev == 0) {
                                is->is_dport = dp;
                                is->is_dend = ntohl(tcp->th_ack);
                        } else {
                                is->is_dport = sp;
                                is->is_dend = ntohl(tcp->th_seq);
                        }
                        is->is_maxdend = is->is_dend + 1;
                }
                is->is_flags &= ~(SI_W_SPORT|SI_W_DPORT);
                if ((flags & SI_CLONED) && ifs->ifs_ipstate_logging)
                        ipstate_log(is, ISL_CLONE, ifs);
        }

        ret = -1;

        if (is->is_flx[out][rev] == 0) {
                is->is_flx[out][rev] = flx;
                /*
                 * If we are dealing with the first packet coming in reverse
                 * direction (sent by peer), then we have to set options into
                 * state.
                 */
                if (rev == 1 && is->is_optmsk[1] == 0x0) {
                        is->is_optmsk[1] = 0xffffffff;
                        is->is_opt[1] = fin->fin_optmsk;
                        DTRACE_PROBE(set_rev_opts);
                }
                if (is->is_v == 6) {
                        is->is_opt[rev] &= ~0x8;
                        is->is_optmsk[rev] &= ~0x8;
                }
        }

        /*
         * Check if the interface name for this "direction" is set and if not,
         * fill it in.
         */
        if (is->is_ifp[idx] == NULL &&
            (*is->is_ifname[idx] == '\0' || *is->is_ifname[idx] == '*')) {
                is->is_ifp[idx] = ifp;
                COPYIFNAME(ifp, is->is_ifname[idx], fin->fin_v);
        }
        fin->fin_rev = rev;
        return is;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_checkicmpmatchingstate                                   */
/* Returns:     Nil                                                         */
/* Parameters:  fin(I) - pointer to packet information                      */
/*                                                                          */
/* If we've got an ICMP error message, using the information stored in the  */
/* ICMP packet, look for a matching state table entry.                      */
/*                                                                          */
/* If we return NULL then no lock on ipf_state is held.                     */
/* If we return non-null then a read-lock on ipf_state is held.             */
/* ------------------------------------------------------------------------ */
static ipstate_t *fr_checkicmpmatchingstate(fin)
fr_info_t *fin;
{
        ipstate_t *is, **isp;
        u_short sport, dport;
        u_char  pr;
        int backward, i, oi;
        i6addr_t dst, src;
        struct icmp *ic;
        u_short savelen;
        icmphdr_t *icmp;
        fr_info_t ofin;
        tcphdr_t *tcp;
        int len;
        ip_t *oip;
        u_int hv;
        ipf_stack_t *ifs = fin->fin_ifs;

        /*
         * Does it at least have the return (basic) IP header ?
         * Is it an actual recognised ICMP error type?
         * Only a basic IP header (no options) should be with
         * an ICMP error header.
         */
        if ((fin->fin_v != 4) || (fin->fin_hlen != sizeof(ip_t)) ||
            (fin->fin_plen < ICMPERR_MINPKTLEN) ||
            !(fin->fin_flx & FI_ICMPERR))
                return NULL;
        ic = fin->fin_dp;

        oip = (ip_t *)((char *)ic + ICMPERR_ICMPHLEN);
        /*
         * Check if the at least the old IP header (with options) and
         * 8 bytes of payload is present.
         */
        if (fin->fin_plen < ICMPERR_MAXPKTLEN + ((IP_HL(oip) - 5) << 2))
                return NULL;

        /*
         * Sanity Checks.
         */
        len = fin->fin_dlen - ICMPERR_ICMPHLEN;
        if ((len <= 0) || ((IP_HL(oip) << 2) > len))
                return NULL;

        /*
         * Is the buffer big enough for all of it ?  It's the size of the IP
         * header claimed in the encapsulated part which is of concern.  It
         * may be too big to be in this buffer but not so big that it's
         * outside the ICMP packet, leading to TCP deref's causing problems.
         * This is possible because we don't know how big oip_hl is when we
         * do the pullup early in fr_check() and thus can't guarantee it is
         * all here now.
         */
#ifdef  _KERNEL
        {
        mb_t *m;

        m = fin->fin_m;
# if defined(MENTAT)
        if ((char *)oip + len > (char *)m->b_wptr)
                return NULL;
# else
        if ((char *)oip + len > (char *)fin->fin_ip + m->m_len)
                return NULL;
# endif
        }
#endif
        bcopy((char *)fin, (char *)&ofin, sizeof(*fin));

        /*
         * in the IPv4 case we must zero the i6addr union otherwise
         * the IP6_EQ and IP6_NEQ macros produce the wrong results because
         * of the 'junk' in the unused part of the union
         */
        bzero((char *)&src, sizeof(src));
        bzero((char *)&dst, sizeof(dst));

        /*
         * we make an fin entry to be able to feed it to
         * matchsrcdst note that not all fields are encessary
         * but this is the cleanest way. Note further we fill
         * in fin_mp such that if someone uses it we'll get
         * a kernel panic. fr_matchsrcdst does not use this.
         *
         * watch out here, as ip is in host order and oip in network
         * order. Any change we make must be undone afterwards, like
         * oip->ip_off - it is still in network byte order so fix it.
         */
        savelen = oip->ip_len;
        oip->ip_len = len;
        oip->ip_off = ntohs(oip->ip_off);

        ofin.fin_flx = FI_NOCKSUM;
        ofin.fin_v = 4;
        ofin.fin_ip = oip;
        ofin.fin_m = NULL;      /* if dereferenced, panic XXX */
        ofin.fin_mp = NULL;     /* if dereferenced, panic XXX */
        ofin.fin_plen = fin->fin_dlen - ICMPERR_ICMPHLEN;
        (void) fr_makefrip(IP_HL(oip) << 2, oip, &ofin);
        ofin.fin_ifp = fin->fin_ifp;
        ofin.fin_out = !fin->fin_out;
        /*
         * Reset the short and bad flag here because in fr_matchsrcdst()
         * the flags for the current packet (fin_flx) are compared against
         * those for the existing session.
         */
        ofin.fin_flx &= ~(FI_BAD|FI_SHORT);

        /*
         * Put old values of ip_len and ip_off back as we don't know
         * if we have to forward the packet (or process it again.
         */
        oip->ip_len = savelen;
        oip->ip_off = htons(oip->ip_off);

        switch (oip->ip_p)
        {
        case IPPROTO_ICMP :
                /*
                 * an ICMP error can only be generated as a result of an
                 * ICMP query, not as the response on an ICMP error
                 *
                 * XXX theoretically ICMP_ECHOREP and the other reply's are
                 * ICMP query's as well, but adding them here seems strange XXX
                 */
                if ((ofin.fin_flx & FI_ICMPERR) != 0)
                        return NULL;

                /*
                 * perform a lookup of the ICMP packet in the state table
                 */
                icmp = (icmphdr_t *)((char *)oip + (IP_HL(oip) << 2));
                hv = (pr = oip->ip_p);
                src.in4 = oip->ip_src;
                hv += src.in4.s_addr;
                dst.in4 = oip->ip_dst;
                hv += dst.in4.s_addr;
                hv += icmp->icmp_id;
                hv = DOUBLE_HASH(hv, ifs);

                READ_ENTER(&ifs->ifs_ipf_state);
                for (isp = &ifs->ifs_ips_table[hv]; ((is = *isp) != NULL); ) {
                        isp = &is->is_hnext;
                        if ((is->is_p != pr) || (is->is_v != 4))
                                continue;
                        if (is->is_pass & FR_NOICMPERR)
                                continue;
                        is = fr_matchsrcdst(&ofin, is, &src, &dst,
                                            NULL, FI_ICMPCMP);
                        if (is != NULL) {
                                if ((is->is_pass & FR_NOICMPERR) != 0) {
                                        RWLOCK_EXIT(&ifs->ifs_ipf_state);
                                        return NULL;
                                }
                                /*
                                 * i  : the index of this packet (the icmp
                                 *      unreachable)
                                 * oi : the index of the original packet found
                                 *      in the icmp header (i.e. the packet
                                 *      causing this icmp)
                                 * backward : original packet was backward
                                 *      compared to the state
                                 */
                                backward = IP6_NEQ(&is->is_src, &src);
                                fin->fin_rev = !backward;
                                i = (!backward << 1) + fin->fin_out;
                                oi = (backward << 1) + ofin.fin_out;
                                if (is->is_icmppkts[i] > is->is_pkts[oi])
                                        continue;
                                ifs->ifs_ips_stats.iss_hits++;
                                is->is_icmppkts[i]++;
                                return is;
                        }
                }
                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                return NULL;
        case IPPROTO_TCP :
        case IPPROTO_UDP :
                break;
        default :
                return NULL;
        }

        tcp = (tcphdr_t *)((char *)oip + (IP_HL(oip) << 2));
        dport = tcp->th_dport;
        sport = tcp->th_sport;

        hv = (pr = oip->ip_p);
        src.in4 = oip->ip_src;
        hv += src.in4.s_addr;
        dst.in4 = oip->ip_dst;
        hv += dst.in4.s_addr;
        hv += dport;
        hv += sport;
        hv = DOUBLE_HASH(hv, ifs);

        READ_ENTER(&ifs->ifs_ipf_state);
        for (isp = &ifs->ifs_ips_table[hv]; ((is = *isp) != NULL); ) {
                isp = &is->is_hnext;
                /*
                 * Only allow this icmp though if the
                 * encapsulated packet was allowed through the
                 * other way around. Note that the minimal amount
                 * of info present does not allow for checking against
                 * tcp internals such as seq and ack numbers.   Only the
                 * ports are known to be present and can be even if the
                 * short flag is set.
                 */
                if ((is->is_p == pr) && (is->is_v == 4) &&
                    (is = fr_matchsrcdst(&ofin, is, &src, &dst,
                                         tcp, FI_ICMPCMP))) {
                        /*
                         * i  : the index of this packet (the icmp unreachable)
                         * oi : the index of the original packet found in the
                         *      icmp header (i.e. the packet causing this icmp)
                         * backward : original packet was backward compared to
                         *            the state
                         */
                        backward = IP6_NEQ(&is->is_src, &src);
                        fin->fin_rev = !backward;
                        i = (!backward << 1) + fin->fin_out;
                        oi = (backward << 1) + ofin.fin_out;

                        if (((is->is_pass & FR_NOICMPERR) != 0) ||
                            (is->is_icmppkts[i] > is->is_pkts[oi]))
                                break;
                        ifs->ifs_ips_stats.iss_hits++;
                        is->is_icmppkts[i]++;
                        /*
                         * we deliberately do not touch the timeouts
                         * for the accompanying state table entry.
                         * It remains to be seen if that is correct. XXX
                         */
                        return is;
                }
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_state);
        return NULL;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_ipsmove                                                  */
/* Returns:     Nil                                                         */
/* Parameters:  is(I) - pointer to state table entry                        */
/*              hv(I) - new hash value for state table entry                */
/* Write Locks: ipf_state                                                   */
/*                                                                          */
/* Move a state entry from one position in the hash table to another.       */
/* ------------------------------------------------------------------------ */
static void fr_ipsmove(is, hv, ifs)
ipstate_t *is;
u_int hv;
ipf_stack_t *ifs;
{
        ipstate_t **isp;
        u_int hvm;

        ASSERT(rw_read_locked(&ifs->ifs_ipf_state.ipf_lk) == 0);

        hvm = is->is_hv;
        /*
         * Remove the hash from the old location...
         */
        isp = is->is_phnext;
        if (is->is_hnext)
                is->is_hnext->is_phnext = isp;
        *isp = is->is_hnext;
        if (ifs->ifs_ips_table[hvm] == NULL)
                ifs->ifs_ips_stats.iss_inuse--;
        ifs->ifs_ips_stats.iss_bucketlen[hvm]--;

        /*
         * ...and put the hash in the new one.
         */
        hvm = DOUBLE_HASH(hv, ifs);
        is->is_hv = hvm;
        isp = &ifs->ifs_ips_table[hvm];
        if (*isp)
                (*isp)->is_phnext = &is->is_hnext;
        else
                ifs->ifs_ips_stats.iss_inuse++;
        ifs->ifs_ips_stats.iss_bucketlen[hvm]++;
        is->is_phnext = isp;
        is->is_hnext = *isp;
        *isp = is;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stlookup                                                 */
/* Returns:     ipstate_t* - NULL == no matching state found,               */
/*                           else pointer to state information is returned  */
/* Parameters:  fin(I) - pointer to packet information                      */
/*              tcp(I) - pointer to TCP/UDP header.                         */
/*                                                                          */
/* Search the state table for a matching entry to the packet described by   */
/* the contents of *fin.                                                    */
/*                                                                          */
/* If we return NULL then no lock on ipf_state is held.                     */
/* If we return non-null then a read-lock on ipf_state is held.             */
/* ------------------------------------------------------------------------ */
ipstate_t *fr_stlookup(fin, tcp, ifqp)
fr_info_t *fin;
tcphdr_t *tcp;
ipftq_t **ifqp;
{
        u_int hv, hvm, pr, v, tryagain;
        ipstate_t *is, **isp;
        u_short dport, sport;
        i6addr_t src, dst;
        struct icmp *ic;
        ipftq_t *ifq;
        int oow;
        ipf_stack_t *ifs = fin->fin_ifs;

        is = NULL;
        ifq = NULL;
        tcp = fin->fin_dp;
        ic = (struct icmp *)tcp;
        hv = (pr = fin->fin_fi.fi_p);
        src = fin->fin_fi.fi_src;
        dst = fin->fin_fi.fi_dst;
        hv += src.in4.s_addr;
        hv += dst.in4.s_addr;

        v = fin->fin_fi.fi_v;
#ifdef  USE_INET6
        if (v == 6) {
                hv  += fin->fin_fi.fi_src.i6[1];
                hv  += fin->fin_fi.fi_src.i6[2];
                hv  += fin->fin_fi.fi_src.i6[3];

                if ((fin->fin_p == IPPROTO_ICMPV6) &&
                    IN6_IS_ADDR_MULTICAST(&fin->fin_fi.fi_dst.in6)) {
                        hv -= dst.in4.s_addr;
                } else {
                        hv += fin->fin_fi.fi_dst.i6[1];
                        hv += fin->fin_fi.fi_dst.i6[2];
                        hv += fin->fin_fi.fi_dst.i6[3];
                }
        }
#endif
        if ((v == 4) &&
            (fin->fin_flx & (FI_MULTICAST|FI_BROADCAST|FI_MBCAST))) {
                if (fin->fin_out == 0) {
                        hv -= src.in4.s_addr;
                } else {
                        hv -= dst.in4.s_addr;
                }
        }

        /*
         * Search the hash table for matching packet header info.
         */
        switch (pr)
        {
#ifdef  USE_INET6
        case IPPROTO_ICMPV6 :
                tryagain = 0;
                if (v == 6) {
                        if ((ic->icmp_type == ICMP6_ECHO_REQUEST) ||
                            (ic->icmp_type == ICMP6_ECHO_REPLY)) {
                                hv += ic->icmp_id;
                        }
                }
                READ_ENTER(&ifs->ifs_ipf_state);
icmp6again:
                hvm = DOUBLE_HASH(hv, ifs);
                for (isp = &ifs->ifs_ips_table[hvm]; ((is = *isp) != NULL); ) {
                        isp = &is->is_hnext;
                        if ((is->is_p != pr) || (is->is_v != v))
                                continue;
                        is = fr_matchsrcdst(fin, is, &src, &dst, NULL, FI_CMP);
                        if (is != NULL &&
                            fr_matchicmpqueryreply(v, &is->is_icmp,
                                                   ic, fin->fin_rev)) {
                                if (fin->fin_rev)
                                        ifq = &ifs->ifs_ips_icmpacktq;
                                else
                                        ifq = &ifs->ifs_ips_icmptq;
                                break;
                        }
                }

                if (is != NULL) {
                        if ((tryagain != 0) && !(is->is_flags & SI_W_DADDR)) {
                                hv += fin->fin_fi.fi_src.i6[0];
                                hv += fin->fin_fi.fi_src.i6[1];
                                hv += fin->fin_fi.fi_src.i6[2];
                                hv += fin->fin_fi.fi_src.i6[3];
                                fr_ipsmove(is, hv, ifs);
                                MUTEX_DOWNGRADE(&ifs->ifs_ipf_state);
                        }
                        break;
                }
                RWLOCK_EXIT(&ifs->ifs_ipf_state);

                /*
                 * No matching icmp state entry. Perhaps this is a
                 * response to another state entry.
                 *
                 * XXX With some ICMP6 packets, the "other" address is already
                 * in the packet, after the ICMP6 header, and this could be
                 * used in place of the multicast address.  However, taking
                 * advantage of this requires some significant code changes
                 * to handle the specific types where that is the case.
                 */
                if ((ifs->ifs_ips_stats.iss_wild != 0) && (v == 6) && (tryagain == 0) &&
                    !IN6_IS_ADDR_MULTICAST(&fin->fin_fi.fi_src.in6)) {
                        hv -= fin->fin_fi.fi_src.i6[0];
                        hv -= fin->fin_fi.fi_src.i6[1];
                        hv -= fin->fin_fi.fi_src.i6[2];
                        hv -= fin->fin_fi.fi_src.i6[3];
                        tryagain = 1;
                        WRITE_ENTER(&ifs->ifs_ipf_state);
                        goto icmp6again;
                }

                is = fr_checkicmp6matchingstate(fin);
                if (is != NULL)
                        return is;
                break;
#endif

        case IPPROTO_ICMP :
                if (v == 4) {
                        hv += ic->icmp_id;
                }
                hv = DOUBLE_HASH(hv, ifs);
                READ_ENTER(&ifs->ifs_ipf_state);
                for (isp = &ifs->ifs_ips_table[hv]; ((is = *isp) != NULL); ) {
                        isp = &is->is_hnext;
                        if ((is->is_p != pr) || (is->is_v != v))
                                continue;
                        is = fr_matchsrcdst(fin, is, &src, &dst, NULL, FI_CMP);
                        if (is != NULL &&
                            fr_matchicmpqueryreply(v, &is->is_icmp,
                                                   ic, fin->fin_rev)) {
                                if (fin->fin_rev)
                                        ifq = &ifs->ifs_ips_icmpacktq;
                                else
                                        ifq = &ifs->ifs_ips_icmptq;
                                break;
                        }
                }
                if (is == NULL) {
                        RWLOCK_EXIT(&ifs->ifs_ipf_state);
                }
                break;

        case IPPROTO_TCP :
        case IPPROTO_UDP :
                ifqp = NULL;
                sport = htons(fin->fin_data[0]);
                hv += sport;
                dport = htons(fin->fin_data[1]);
                hv += dport;
                oow = 0;
                tryagain = 0;
                READ_ENTER(&ifs->ifs_ipf_state);
retry_tcpudp:
                hvm = DOUBLE_HASH(hv, ifs);
                for (isp = &ifs->ifs_ips_table[hvm]; ((is = *isp) != NULL); ) {
                        isp = &is->is_hnext;
                        if ((is->is_p != pr) || (is->is_v != v))
                                continue;
                        fin->fin_flx &= ~FI_OOW;
                        is = fr_matchsrcdst(fin, is, &src, &dst, tcp, FI_CMP);
                        if (is != NULL) {
                                if (pr == IPPROTO_TCP) {
                                        if (!fr_tcpstate(fin, tcp, is)) {
                                                oow |= fin->fin_flx & FI_OOW;
                                                continue;
                                        }
                                }
                                break;
                        }
                }
                if (is != NULL) {
                        if (tryagain &&
                            !(is->is_flags & (SI_CLONE|SI_WILDP|SI_WILDA))) {
                                hv += dport;
                                hv += sport;
                                fr_ipsmove(is, hv, ifs);
                                MUTEX_DOWNGRADE(&ifs->ifs_ipf_state);
                        }
                        break;
                }
                RWLOCK_EXIT(&ifs->ifs_ipf_state);

                if (ifs->ifs_ips_stats.iss_wild) {
                        if (tryagain == 0) {
                                hv -= dport;
                                hv -= sport;
                        } else if (tryagain == 1) {
                                hv = fin->fin_fi.fi_p;
                                /*
                                 * If we try to pretend this is a reply to a
                                 * multicast/broadcast packet then we need to
                                 * exclude part of the address from the hash
                                 * calculation.
                                 */
                                if (fin->fin_out == 0) {
                                        hv += src.in4.s_addr;
                                } else {
                                        hv += dst.in4.s_addr;
                                }
                                hv += dport;
                                hv += sport;
                        }
                        tryagain++;
                        if (tryagain <= 2) {
                                WRITE_ENTER(&ifs->ifs_ipf_state);
                                goto retry_tcpudp;
                        }
                }
                fin->fin_flx |= oow;
                break;

#if 0
        case IPPROTO_GRE :
                gre = fin->fin_dp;
                if (GRE_REV(gre->gr_flags) == 1) {
                        hv += gre->gr_call;
                }
                /* FALLTHROUGH */
#endif
        default :
                ifqp = NULL;
                hvm = DOUBLE_HASH(hv, ifs);
                READ_ENTER(&ifs->ifs_ipf_state);
                for (isp = &ifs->ifs_ips_table[hvm]; ((is = *isp) != NULL); ) {
                        isp = &is->is_hnext;
                        if ((is->is_p != pr) || (is->is_v != v))
                                continue;
                        is = fr_matchsrcdst(fin, is, &src, &dst, NULL, FI_CMP);
                        if (is != NULL) {
                                ifq = &ifs->ifs_ips_iptq;
                                break;
                        }
                }
                if (is == NULL) {
                        RWLOCK_EXIT(&ifs->ifs_ipf_state);
                }
                break;
        }

        if ((is != NULL) && ((is->is_sti.tqe_flags & TQE_RULEBASED) != 0) &&
            (is->is_tqehead[fin->fin_rev] != NULL))
                ifq = is->is_tqehead[fin->fin_rev];
        if (ifq != NULL && ifqp != NULL)
                *ifqp = ifq;
        return is;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_updatestate                                              */
/* Returns:     Nil                                                         */
/* Parameters:  fin(I) - pointer to packet information                      */
/*              is(I)  - pointer to state table entry                       */
/* Read Locks:  ipf_state                                                   */
/*                                                                          */
/* Updates packet and byte counters for a newly received packet.  Seeds the */
/* fragment cache with a new entry as required.                             */
/* ------------------------------------------------------------------------ */
void fr_updatestate(fin, is, ifq)
fr_info_t *fin;
ipstate_t *is;
ipftq_t *ifq;
{
        ipftqent_t *tqe;
        int i, pass;
        ipf_stack_t *ifs = fin->fin_ifs;

        i = (fin->fin_rev << 1) + fin->fin_out;

        /*
         * For TCP packets, ifq == NULL.  For all others, check if this new
         * queue is different to the last one it was on and move it if so.
         */
        tqe = &is->is_sti;
        MUTEX_ENTER(&is->is_lock);
        if ((tqe->tqe_flags & TQE_RULEBASED) != 0)
                ifq = is->is_tqehead[fin->fin_rev];

        if (ifq != NULL)
                fr_movequeue(tqe, tqe->tqe_ifq, ifq, ifs);

        is->is_pkts[i]++;
        fin->fin_pktnum = is->is_pkts[i] + is->is_icmppkts[i];
        is->is_bytes[i] += fin->fin_plen;
        MUTEX_EXIT(&is->is_lock);

#ifdef  IPFILTER_SYNC
        if (is->is_flags & IS_STATESYNC)
                ipfsync_update(SMC_STATE, fin, is->is_sync);
#endif

        ATOMIC_INCL(ifs->ifs_ips_stats.iss_hits);

        fin->fin_fr = is->is_rule;

        /*
         * If this packet is a fragment and the rule says to track fragments,
         * then create a new fragment cache entry.
         */
        pass = is->is_pass;
        if ((fin->fin_flx & FI_FRAG) && FR_ISPASS(pass))
                (void) fr_newfrag(fin, pass ^ FR_KEEPSTATE);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_checkstate                                               */
/* Returns:     frentry_t* - NULL == search failed,                         */
/*                           else pointer to rule for matching state        */
/* Parameters:  ifp(I)   - pointer to interface                             */
/*              passp(I) - pointer to filtering result flags                */
/*                                                                          */
/* Check if a packet is associated with an entry in the state table.        */
/* ------------------------------------------------------------------------ */
frentry_t *fr_checkstate(fin, passp)
fr_info_t *fin;
u_32_t *passp;
{
        ipstate_t *is;
        frentry_t *fr;
        tcphdr_t *tcp;
        ipftq_t *ifq;
        u_int pass;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_state_lock || (ifs->ifs_ips_list == NULL) ||
            (fin->fin_flx & (FI_SHORT|FI_STATE|FI_FRAGBODY|FI_BAD)))
                return NULL;

        is = NULL;
        if ((fin->fin_flx & FI_TCPUDP) ||
            (fin->fin_fi.fi_p == IPPROTO_ICMP)
#ifdef  USE_INET6
            || (fin->fin_fi.fi_p == IPPROTO_ICMPV6)
#endif
            )
                tcp = fin->fin_dp;
        else
                tcp = NULL;

        /*
         * Search the hash table for matching packet header info.
         */
        ifq = NULL;
        is = fr_stlookup(fin, tcp, &ifq);
        switch (fin->fin_p)
        {
#ifdef  USE_INET6
        case IPPROTO_ICMPV6 :
                if (is != NULL)
                        break;
                if (fin->fin_v == 6) {
                        is = fr_checkicmp6matchingstate(fin);
                        if (is != NULL)
                                goto matched;
                }
                break;
#endif
        case IPPROTO_ICMP :
                if (is != NULL)
                        break;
                /*
                 * No matching icmp state entry. Perhaps this is a
                 * response to another state entry.
                 */
                is = fr_checkicmpmatchingstate(fin);
                if (is != NULL)
                        goto matched;
                break;
        case IPPROTO_TCP :
                if (is == NULL)
                        break;

                if (is->is_pass & FR_NEWISN) {
                        if (fin->fin_out == 0)
                                fr_fixinisn(fin, is);
                        else if (fin->fin_out == 1)
                                fr_fixoutisn(fin, is);
                }
                break;
        default :
                if (fin->fin_rev)
                        ifq = &ifs->ifs_ips_udpacktq;
                else
                        ifq = &ifs->ifs_ips_udptq;
                break;
        }
        if (is == NULL) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_miss);
                return NULL;
        }

matched:
        fr = is->is_rule;
        if (fr != NULL) {
                if ((fin->fin_out == 0) && (fr->fr_nattag.ipt_num[0] != 0)) {
                        if (fin->fin_nattag == NULL) {
                                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                                return NULL;
                        }
                        if (fr_matchtag(&fr->fr_nattag, fin->fin_nattag) != 0) {
                                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                                return NULL;
                        }
                }
                (void) strncpy(fin->fin_group, fr->fr_group, FR_GROUPLEN);
                fin->fin_icode = fr->fr_icode;
        }

        fin->fin_rule = is->is_rulen;
        pass = is->is_pass;
        fr_updatestate(fin, is, ifq);

        RWLOCK_EXIT(&ifs->ifs_ipf_state);
        fin->fin_flx |= FI_STATE;
        if ((pass & FR_LOGFIRST) != 0)
                pass &= ~(FR_LOGFIRST|FR_LOG);
        *passp = pass;
        return fr;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fixoutisn                                                */
/* Returns:     Nil                                                         */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              is(I)  - pointer to master state structure                  */
/*                                                                          */
/* Called only for outbound packets, adjusts the sequence number and the    */
/* TCP checksum to match that change.                                       */
/* ------------------------------------------------------------------------ */
static void fr_fixoutisn(fin, is)
fr_info_t *fin;
ipstate_t *is;
{
        tcphdr_t *tcp;
        int rev;
        u_32_t seq;

        tcp = fin->fin_dp;
        rev = fin->fin_rev;
        if ((is->is_flags & IS_ISNSYN) != 0) {
                if (rev == 0) {
                        seq = ntohl(tcp->th_seq);
                        seq += is->is_isninc[0];
                        tcp->th_seq = htonl(seq);
                        fix_outcksum(&tcp->th_sum, is->is_sumd[0]);
                }
        }
        if ((is->is_flags & IS_ISNACK) != 0) {
                if (rev == 1) {
                        seq = ntohl(tcp->th_seq);
                        seq += is->is_isninc[1];
                        tcp->th_seq = htonl(seq);
                        fix_outcksum(&tcp->th_sum, is->is_sumd[1]);
                }
        }
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fixinisn                                                 */
/* Returns:     Nil                                                         */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              is(I)  - pointer to master state structure                  */
/*                                                                          */
/* Called only for inbound packets, adjusts the acknowledge number and the  */
/* TCP checksum to match that change.                                       */
/* ------------------------------------------------------------------------ */
static void fr_fixinisn(fin, is)
fr_info_t *fin;
ipstate_t *is;
{
        tcphdr_t *tcp;
        int rev;
        u_32_t ack;

        tcp = fin->fin_dp;
        rev = fin->fin_rev;
        if ((is->is_flags & IS_ISNSYN) != 0) {
                if (rev == 1) {
                        ack = ntohl(tcp->th_ack);
                        ack -= is->is_isninc[0];
                        tcp->th_ack = htonl(ack);
                        fix_incksum(&tcp->th_sum, is->is_sumd[0]);
                }
        }
        if ((is->is_flags & IS_ISNACK) != 0) {
                if (rev == 0) {
                        ack = ntohl(tcp->th_ack);
                        ack -= is->is_isninc[1];
                        tcp->th_ack = htonl(ack);
                        fix_incksum(&tcp->th_sum, is->is_sumd[1]);
                }
        }
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_statesync                                                */
/* Returns:     Nil                                                         */
/* Parameters:  action(I) - type of synchronisation to do                   */
/*              v(I)      - IP version being sync'd (v4 or v6)              */
/*              ifp(I)    - interface identifier associated with action     */
/*              name(I)   - name associated with ifp parameter              */
/*                                                                          */
/* Walk through all state entries and if an interface pointer match is      */
/* found then look it up again, based on its name in case the pointer has   */
/* changed since last time.                                                 */
/*                                                                          */
/* If ifp is passed in as being non-null then we are only doing updates for */
/* existing, matching, uses of it.                                          */
/* ------------------------------------------------------------------------ */
void fr_statesync(action, v, ifp, name, ifs)
int action, v;
void *ifp;
char *name;
ipf_stack_t *ifs;
{
        ipstate_t *is;
        int i;

        if (ifs->ifs_fr_running <= 0)
                return;

        WRITE_ENTER(&ifs->ifs_ipf_state);

        if (ifs->ifs_fr_running <= 0) {
                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                return;
        }

        switch (action)
        {
        case IPFSYNC_RESYNC :
                for (is = ifs->ifs_ips_list; is; is = is->is_next) {
                        if (v != 0 && is->is_v != v)
                                continue;
                        /*
                         * Look up all the interface names in the state entry.
                         */
                        for (i = 0; i < 4; i++) {
                                is->is_ifp[i] = fr_resolvenic(is->is_ifname[i],
                                                              is->is_v, ifs);
                        }
                }
                break;
        case IPFSYNC_NEWIFP :
                for (is = ifs->ifs_ips_list; is; is = is->is_next) {
                        if (v != 0 && is->is_v != v)
                                continue;
                        /*
                         * Look up all the interface names in the state entry.
                         */
                        for (i = 0; i < 4; i++) {
                                if (!strncmp(is->is_ifname[i], name,
                                             sizeof(is->is_ifname[i])))
                                        is->is_ifp[i] = ifp;
                        }
                }
                break;
        case IPFSYNC_OLDIFP :
                for (is = ifs->ifs_ips_list; is; is = is->is_next) {
                        if (v != 0 && is->is_v != v)
                                continue;
                        /*
                         * Look up all the interface names in the state entry.
                         */
                        for (i = 0; i < 4; i++) {
                                if (is->is_ifp[i] == ifp)
                                        is->is_ifp[i] = (void *)-1;
                        }
                }
                break;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_state);
}


#if SOLARIS2 >= 10
/* ------------------------------------------------------------------------ */
/* Function:    fr_stateifindexsync                                         */
/* Returns:     void                                                        */
/* Parameters:  ifp     - current network interface descriptor (ifindex)    */
/*              newifp  - new interface descriptor (new ifindex)            */
/*              ifs     - pointer to IPF stack                              */
/*                                                                          */
/* Write Locks: assumes ipf_mutex is locked                                 */
/*                                                                          */
/* Updates all interface indeces matching to ifp with new interface index   */
/* value.                                                                   */
/* ------------------------------------------------------------------------ */
void fr_stateifindexsync(ifp, newifp, ifs)
void *ifp;
void *newifp;
ipf_stack_t *ifs;
{
        ipstate_t *is;
        int i;

        WRITE_ENTER(&ifs->ifs_ipf_state);

        for (is = ifs->ifs_ips_list; is != NULL; is = is->is_next) {

                for (i = 0; i < 4; i++) {
                        if (is->is_ifp[i] == ifp)
                                is->is_ifp[i] = newifp;
                }
        }

        RWLOCK_EXIT(&ifs->ifs_ipf_state);
}
#endif

/* ------------------------------------------------------------------------ */
/* Function:    fr_delstate                                                 */
/* Returns:     int - 0 = entry deleted, else ref count on entry            */
/* Parameters:  is(I)  - pointer to state structure to delete               */
/*              why(I) - if not 0, log reason why it was deleted            */
/*              ifs    - ipf stack instance                                 */
/* Write Locks: ipf_state/ipf_global                                        */
/*                                                                          */
/* Deletes a state entry from the enumerated list as well as the hash table */
/* and timeout queue lists.  Make adjustments to hash table statistics and  */
/* global counters as required.                                             */
/* ------------------------------------------------------------------------ */
int fr_delstate(is, why, ifs)
ipstate_t *is;
int why;
ipf_stack_t *ifs;
{
        int removed = 0;

        ASSERT(rw_write_held(&ifs->ifs_ipf_global.ipf_lk) == 0 ||
                rw_write_held(&ifs->ifs_ipf_state.ipf_lk) == 0);

        /*
         * Start by removing the entry from the hash table of state entries
         * so it will not be "used" again.
         *
         * It will remain in the "list" of state entries until all references
         * have been accounted for.
         */
        if (is->is_phnext != NULL) {
                removed = 1;
                *is->is_phnext = is->is_hnext;
                if (is->is_hnext != NULL)
                        is->is_hnext->is_phnext = is->is_phnext;
                if (ifs->ifs_ips_table[is->is_hv] == NULL)
                        ifs->ifs_ips_stats.iss_inuse--;
                ifs->ifs_ips_stats.iss_bucketlen[is->is_hv]--;

                is->is_phnext = NULL;
                is->is_hnext = NULL;
        }

        /*
         * Because ifs->ifs_ips_stats.iss_wild is a count of entries in the state
         * table that have wildcard flags set, only decerement it once
         * and do it here.
         */
        if (is->is_flags & (SI_WILDP|SI_WILDA)) {
                if (!(is->is_flags & SI_CLONED)) {
                        ATOMIC_DECL(ifs->ifs_ips_stats.iss_wild);
                }
                is->is_flags &= ~(SI_WILDP|SI_WILDA);
        }

        /*
         * Next, remove it from the timeout queue it is in.
         */
        fr_deletequeueentry(&is->is_sti);

        is->is_me = NULL;

        /*
         * If it is still in use by something else, do not go any further,
         * but note that at this point it is now an orphan.
         */
        MUTEX_ENTER(&is->is_lock);
        if (is->is_ref > 1) {
                is->is_ref--;
                MUTEX_EXIT(&is->is_lock);
                if (removed)
                        ifs->ifs_ips_stats.iss_orphans++;
                return (is->is_ref);
        }
        MUTEX_EXIT(&is->is_lock);

        is->is_ref = 0;

        /*
         * If entry has already been removed from table,
         * it means we're simply cleaning up an orphan.
         */
        if (!removed)
                ifs->ifs_ips_stats.iss_orphans--;

        if (is->is_tqehead[0] != NULL)
                (void) fr_deletetimeoutqueue(is->is_tqehead[0]);

        if (is->is_tqehead[1] != NULL)
                (void) fr_deletetimeoutqueue(is->is_tqehead[1]);

#ifdef  IPFILTER_SYNC
        if (is->is_sync)
                ipfsync_del(is->is_sync);
#endif
#ifdef  IPFILTER_SCAN
        (void) ipsc_detachis(is);
#endif

        /*
         * Now remove it from master list of state table entries.
         */
        if (is->is_pnext != NULL) {
                *is->is_pnext = is->is_next;
                if (is->is_next != NULL) {
                        is->is_next->is_pnext = is->is_pnext;
                        is->is_next = NULL;
                }
                is->is_pnext = NULL;
        }

        if (ifs->ifs_ipstate_logging != 0 && why != 0)
                ipstate_log(is, why, ifs);

        if (is->is_rule != NULL) {
                is->is_rule->fr_statecnt--;
                (void)fr_derefrule(&is->is_rule, ifs);
        }

        MUTEX_DESTROY(&is->is_lock);
        KFREE(is);
        ifs->ifs_ips_num--;

        return (0);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_timeoutstate                                             */
/* Returns:     Nil                                                         */
/* Parameters:  ifs - ipf stack instance                                    */
/*                                                                          */
/* Slowly expire held state for thingslike UDP and ICMP.  The algorithm     */
/* used here is to keep the queue sorted with the oldest things at the top  */
/* and the youngest at the bottom.  So if the top one doesn't need to be    */
/* expired then neither will any under it.                                  */
/* ------------------------------------------------------------------------ */
void fr_timeoutstate(ifs)
ipf_stack_t *ifs;
{
        ipftq_t *ifq, *ifqnext;
        ipftqent_t *tqe, *tqn;
        ipstate_t *is;
        SPL_INT(s);

        SPL_NET(s);
        WRITE_ENTER(&ifs->ifs_ipf_state);
        for (ifq = ifs->ifs_ips_tqtqb; ifq != NULL; ifq = ifq->ifq_next)
                for (tqn = ifq->ifq_head; ((tqe = tqn) != NULL); ) {
                        if (tqe->tqe_die > ifs->ifs_fr_ticks)
                                break;
                        tqn = tqe->tqe_next;
                        is = tqe->tqe_parent;
                        (void) fr_delstate(is, ISL_EXPIRE, ifs);
                }

        for (ifq = ifs->ifs_ips_utqe; ifq != NULL; ifq = ifq->ifq_next) {
                for (tqn = ifq->ifq_head; ((tqe = tqn) != NULL); ) {
                        if (tqe->tqe_die > ifs->ifs_fr_ticks)
                                break;
                        tqn = tqe->tqe_next;
                        is = tqe->tqe_parent;
                        (void) fr_delstate(is, ISL_EXPIRE, ifs);
                }
        }

        for (ifq = ifs->ifs_ips_utqe; ifq != NULL; ifq = ifqnext) {
                ifqnext = ifq->ifq_next;

                if (((ifq->ifq_flags & IFQF_DELETE) != 0) &&
                    (ifq->ifq_ref == 0)) {
                        fr_freetimeoutqueue(ifq, ifs);
                }
        }

        if (ifs->ifs_fr_state_doflush) {
                (void) fr_state_flush(FLUSH_TABLE_EXTRA, 0, ifs);
                ifs->ifs_fr_state_doflush = 0;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_state);
        SPL_X(s);
}


/* ---------------------------------------------------------------------- */
/* Function:    fr_state_flush                                            */
/* Returns:     int - 0 == success, -1 == failure                         */
/* Parameters:  flush_option - how to flush the active State table        */
/*              proto    - IP version to flush (4, 6, or both)            */
/*              ifs      - ipf stack instance                             */
/* Write Locks: ipf_state                                                 */
/*                                                                        */
/* Flush state tables.  Three possible flush options currently defined:   */
/*                                                                        */
/* FLUSH_TABLE_ALL      : Flush all state table entries                   */
/*                                                                        */
/* FLUSH_TABLE_CLOSING  : Flush entries with TCP connections which        */
/*                        have started to close on both ends using        */
/*                        ipf_flushclosing().                             */
/*                                                                        */
/* FLUSH_TABLE_EXTRA    : First, flush entries which are "almost" closed. */
/*                        Then, if needed, flush entries with TCP         */
/*                        connections which have been idle for a long     */
/*                        time with ipf_extraflush().                     */
/* ---------------------------------------------------------------------- */
static int fr_state_flush(flush_option, proto, ifs)
int flush_option, proto;
ipf_stack_t *ifs;
{
        ipstate_t *is, *isn;
        int removed;
        SPL_INT(s);

        removed = 0;

        SPL_NET(s);
        switch (flush_option)
        {
        case FLUSH_TABLE_ALL:
                isn = ifs->ifs_ips_list;
                while ((is = isn) != NULL) {
                        isn = is->is_next;
                        if ((proto != 0) && (is->is_v != proto))
                                continue;
                        if (fr_delstate(is, ISL_FLUSH, ifs) == 0)
                                removed++;
                }
                break;

        case FLUSH_TABLE_CLOSING:
                removed = ipf_flushclosing(STATE_FLUSH,
                                           IPF_TCPS_CLOSE_WAIT,
                                           ifs->ifs_ips_tqtqb,
                                           ifs->ifs_ips_utqe,
                                           ifs);
                break;

        case FLUSH_TABLE_EXTRA:
                removed = ipf_flushclosing(STATE_FLUSH,
                                           IPF_TCPS_FIN_WAIT_2,
                                           ifs->ifs_ips_tqtqb,
                                           ifs->ifs_ips_utqe,
                                           ifs);

                /*
                 * Be sure we haven't done this in the last 10 seconds.
                 */
                if (ifs->ifs_fr_ticks - ifs->ifs_ips_last_force_flush <
                    IPF_TTLVAL(10))
                        break;
                ifs->ifs_ips_last_force_flush = ifs->ifs_fr_ticks;
                removed += ipf_extraflush(STATE_FLUSH,
                                          &ifs->ifs_ips_tqtqb[IPF_TCPS_ESTABLISHED],
                                          ifs->ifs_ips_utqe,
                                          ifs);
                break;

        default: /* Flush Nothing */
                break;
        }

        SPL_X(s);
        return (removed);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_tcp_age                                                  */
/* Returns:     int - 1 == state transition made, 0 == no change (rejected) */
/* Parameters:  tq(I)    - pointer to timeout queue information             */
/*              fin(I)   - pointer to packet information                    */
/*              tqtab(I) - TCP timeout queue table this is in               */
/*              flags(I) - flags from state/NAT entry                       */
/*                                                                          */
/* Rewritten by Arjan de Vet <Arjan.deVet@adv.iae.nl>, 2000-07-29:          */
/*                                                                          */
/* - (try to) base state transitions on real evidence only,                 */
/*   i.e. packets that are sent and have been received by ipfilter;         */
/*   diagram 18.12 of TCP/IP volume 1 by W. Richard Stevens was used.       */
/*                                                                          */
/* - deal with half-closed connections correctly;                           */
/*                                                                          */
/* - store the state of the source in state[0] such that ipfstat            */
/*   displays the state as source/dest instead of dest/source; the calls    */
/*   to fr_tcp_age have been changed accordingly.                           */
/*                                                                          */
/* Internal Parameters:                                                     */
/*                                                                          */
/*    state[0] = state of source (host that initiated connection)           */
/*    state[1] = state of dest   (host that accepted the connection)        */
/*                                                                          */
/*    dir == 0 : a packet from source to dest                               */
/*    dir == 1 : a packet from dest to source                               */
/*                                                                          */
/* Locking: it is assumed that the parent of the tqe structure is locked.   */
/* ------------------------------------------------------------------------ */
int fr_tcp_age(tqe, fin, tqtab, flags)
ipftqent_t *tqe;
fr_info_t *fin;
ipftq_t *tqtab;
int flags;
{
        int dlen, ostate, nstate, rval, dir;
        u_char tcpflags;
        tcphdr_t *tcp;
        ipf_stack_t *ifs = fin->fin_ifs;

        tcp = fin->fin_dp;

        rval = 0;
        dir = fin->fin_rev;
        tcpflags = tcp->th_flags;
        dlen = fin->fin_dlen - (TCP_OFF(tcp) << 2);

        ostate = tqe->tqe_state[1 - dir];
        nstate = tqe->tqe_state[dir];

        DTRACE_PROBE4(
                indata,
                fr_info_t *, fin,
                int, ostate,
                int, nstate,
                u_char, tcpflags
        );

        if (tcpflags & TH_RST) {
                if (!(tcpflags & TH_PUSH) && !dlen)
                        nstate = IPF_TCPS_CLOSED;
                else
                        nstate = IPF_TCPS_CLOSE_WAIT;

                /*
                 * Once RST is received, we must advance peer's state to
                 * CLOSE_WAIT.
                 */
                if (ostate <= IPF_TCPS_ESTABLISHED) {
                        tqe->tqe_state[1 - dir] = IPF_TCPS_CLOSE_WAIT;
                }
                rval = 1;
        } else {

                switch (nstate)
                {
                case IPF_TCPS_LISTEN: /* 0 */
                        if ((tcpflags & TH_OPENING) == TH_OPENING) {
                                /*
                                 * 'dir' received an S and sends SA in
                                 * response, CLOSED -> SYN_RECEIVED
                                 */
                                nstate = IPF_TCPS_SYN_RECEIVED;
                                rval = 1;
                        } else if ((tcpflags & TH_OPENING) == TH_SYN) {
                                /* 'dir' sent S, CLOSED -> SYN_SENT */
                                nstate = IPF_TCPS_SYN_SENT;
                                rval = 1;
                        }
                        /*
                         * the next piece of code makes it possible to get
                         * already established connections into the state table
                         * after a restart or reload of the filter rules; this
                         * does not work when a strict 'flags S keep state' is
                         * used for tcp connections of course
                         */
                        if (((flags & IS_TCPFSM) == 0) &&
                            ((tcpflags & TH_ACKMASK) == TH_ACK)) {
                                /*
                                 * we saw an A, guess 'dir' is in ESTABLISHED
                                 * mode
                                 */
                                switch (ostate)
                                {
                                case IPF_TCPS_LISTEN :
                                case IPF_TCPS_SYN_RECEIVED :
                                        nstate = IPF_TCPS_HALF_ESTAB;
                                        rval = 1;
                                        break;
                                case IPF_TCPS_HALF_ESTAB :
                                case IPF_TCPS_ESTABLISHED :
                                        nstate = IPF_TCPS_ESTABLISHED;
                                        rval = 1;
                                        break;
                                default :
                                        break;
                                }
                        }
                        /*
                         * TODO: besides regular ACK packets we can have other
                         * packets as well; it is yet to be determined how we
                         * should initialize the states in those cases
                         */
                        break;

                case IPF_TCPS_SYN_SENT: /* 1 */
                        if ((tcpflags & ~(TH_ECN|TH_CWR)) == TH_SYN) {
                                /*
                                 * A retransmitted SYN packet.  We do not reset
                                 * the timeout here to fr_tcptimeout because a
                                 * connection connect timeout does not renew
                                 * after every packet that is sent.  We need to
                                 * set rval so as to indicate the packet has
                                 * passed the check for its flags being valid
                                 * in the TCP FSM.  Setting rval to 2 has the
                                 * result of not resetting the timeout.
                                 */
                                rval = 2;
                        } else if ((tcpflags & (TH_SYN|TH_FIN|TH_ACK)) ==
                                   TH_ACK) {
                                /*
                                 * we see an A from 'dir' which is in SYN_SENT
                                 * state: 'dir' sent an A in response to an SA
                                 * which it received, SYN_SENT -> ESTABLISHED
                                 */
                                nstate = IPF_TCPS_ESTABLISHED;
                                rval = 1;
                        } else if (tcpflags & TH_FIN) {
                                /*
                                 * we see an F from 'dir' which is in SYN_SENT
                                 * state and wants to close its side of the
                                 * connection; SYN_SENT -> FIN_WAIT_1
                                 */
                                nstate = IPF_TCPS_FIN_WAIT_1;
                                rval = 1;
                        } else if ((tcpflags & TH_OPENING) == TH_OPENING) {
                                /*
                                 * we see an SA from 'dir' which is already in
                                 * SYN_SENT state, this means we have a
                                 * simultaneous open; SYN_SENT -> SYN_RECEIVED
                                 */
                                nstate = IPF_TCPS_SYN_RECEIVED;
                                rval = 1;
                        }
                        break;

                case IPF_TCPS_SYN_RECEIVED: /* 2 */
                        if ((tcpflags & (TH_SYN|TH_FIN|TH_ACK)) == TH_ACK) {
                                /*
                                 * we see an A from 'dir' which was in
                                 * SYN_RECEIVED state so it must now be in
                                 * established state, SYN_RECEIVED ->
                                 * ESTABLISHED
                                 */
                                nstate = IPF_TCPS_ESTABLISHED;
                                rval = 1;
                        } else if ((tcpflags & ~(TH_ECN|TH_CWR)) ==
                                   TH_OPENING) {
                                /*
                                 * We see an SA from 'dir' which is already in
                                 * SYN_RECEIVED state.
                                 */
                                rval = 2;
                        } else if (tcpflags & TH_FIN) {
                                /*
                                 * we see an F from 'dir' which is in
                                 * SYN_RECEIVED state and wants to close its
                                 * side of the connection; SYN_RECEIVED ->
                                 * FIN_WAIT_1
                                 */
                                nstate = IPF_TCPS_FIN_WAIT_1;
                                rval = 1;
                        }
                        break;

                case IPF_TCPS_HALF_ESTAB: /* 3 */
                        if (tcpflags & TH_FIN) {
                                nstate = IPF_TCPS_FIN_WAIT_1;
                                rval = 1;
                        } else if ((tcpflags & TH_ACKMASK) == TH_ACK) {
                                /*
                                 * If we've picked up a connection in mid
                                 * flight, we could be looking at a follow on
                                 * packet from the same direction as the one
                                 * that created this state.  Recognise it but
                                 * do not advance the entire connection's
                                 * state.
                                 */
                                switch (ostate)
                                {
                                case IPF_TCPS_LISTEN :
                                case IPF_TCPS_SYN_SENT :
                                case IPF_TCPS_SYN_RECEIVED :
                                        rval = 1;
                                        break;
                                case IPF_TCPS_HALF_ESTAB :
                                case IPF_TCPS_ESTABLISHED :
                                        nstate = IPF_TCPS_ESTABLISHED;
                                        rval = 1;
                                        break;
                                default :
                                        break;
                                }
                        }
                        break;

                case IPF_TCPS_ESTABLISHED: /* 4 */
                        rval = 1;
                        if (tcpflags & TH_FIN) {
                                /*
                                 * 'dir' closed its side of the connection;
                                 * this gives us a half-closed connection;
                                 * ESTABLISHED -> FIN_WAIT_1
                                 */
                                if (ostate == IPF_TCPS_FIN_WAIT_1) {
                                        nstate = IPF_TCPS_CLOSING;
                                } else {
                                        nstate = IPF_TCPS_FIN_WAIT_1;
                                }
                        } else if (tcpflags & TH_ACK) {
                                /*
                                 * an ACK, should we exclude other flags here?
                                 */
                                if (ostate == IPF_TCPS_FIN_WAIT_1) {
                                        /*
                                         * We know the other side did an active
                                         * close, so we are ACKing the recvd
                                         * FIN packet (does the window matching
                                         * code guarantee this?) and go into
                                         * CLOSE_WAIT state; this gives us a
                                         * half-closed connection
                                         */
                                        nstate = IPF_TCPS_CLOSE_WAIT;
                                } else if (ostate < IPF_TCPS_CLOSE_WAIT) {
                                        /*
                                         * still a fully established
                                         * connection reset timeout
                                         */
                                        nstate = IPF_TCPS_ESTABLISHED;
                                }
                        }
                        break;

                case IPF_TCPS_CLOSE_WAIT: /* 5 */
                        rval = 1;
                        if (tcpflags & TH_FIN) {
                                /*
                                 * application closed and 'dir' sent a FIN,
                                 * we're now going into LAST_ACK state
                                 */
                                nstate = IPF_TCPS_LAST_ACK;
                        } else {
                                /*
                                 * we remain in CLOSE_WAIT because the other
                                 * side has closed already and we did not
                                 * close our side yet; reset timeout
                                 */
                                nstate = IPF_TCPS_CLOSE_WAIT;
                        }
                        break;

                case IPF_TCPS_FIN_WAIT_1: /* 6 */
                        rval = 1;
                        if ((tcpflags & TH_ACK) &&
                            ostate > IPF_TCPS_CLOSE_WAIT) {
                                /*
                                 * if the other side is not active anymore
                                 * it has sent us a FIN packet that we are
                                 * ack'ing now with an ACK; this means both
                                 * sides have now closed the connection and
                                 * we go into LAST_ACK
                                 */
                                /*
                                 * XXX: how do we know we really are ACKing
                                 * the FIN packet here? does the window code
                                 * guarantee that?
                                 */
                                nstate = IPF_TCPS_LAST_ACK;
                        } else {
                                /*
                                 * we closed our side of the connection
                                 * already but the other side is still active
                                 * (ESTABLISHED/CLOSE_WAIT); continue with
                                 * this half-closed connection
                                 */
                                nstate = IPF_TCPS_FIN_WAIT_1;
                        }
                        break;

                case IPF_TCPS_CLOSING: /* 7 */
                        if ((tcpflags & (TH_FIN|TH_ACK)) == TH_ACK) {
                                nstate = IPF_TCPS_TIME_WAIT;
                        }
                        rval = 1;
                        break;

                case IPF_TCPS_LAST_ACK: /* 8 */
                        /*
                         * We want to reset timer here to keep state in table.
                         * If we would allow the state to time out here, while
                         * there would still be packets being retransmitted, we
                         * would cut off line between the two peers preventing
                         * them to close connection properly.
                         */
                        rval = 1;
                        break;

                case IPF_TCPS_FIN_WAIT_2: /* 9 */
                        /* NOT USED */
                        break;

                case IPF_TCPS_TIME_WAIT: /* 10 */
                        /* we're in 2MSL timeout now */
                        if (ostate == IPF_TCPS_LAST_ACK) {
                                nstate = IPF_TCPS_CLOSED;
                                rval = 1;
                        } else {
                                rval = 2;
                        }
                        break;

                case IPF_TCPS_CLOSED: /* 11 */
                        rval = 2;
                        break;

                default :
#if defined(_KERNEL)
                        ASSERT(nstate >= IPF_TCPS_LISTEN &&
                            nstate <= IPF_TCPS_CLOSED);
#else
                        abort();
#endif
                        break;
                }
        }

        /*
         * If rval == 2 then do not update the queue position, but treat the
         * packet as being ok.
         */
        if (rval == 2) {
                DTRACE_PROBE1(state_keeping_timer, int, nstate);
                rval = 1;
        }
        else if (rval == 1) {
                tqe->tqe_state[dir] = nstate;
                /*
                 * The nstate can either advance to a new state, or remain
                 * unchanged, resetting the timer by moving to the bottom of
                 * the queue.
                 */
                DTRACE_PROBE1(state_done, int, nstate);

                if ((tqe->tqe_flags & TQE_RULEBASED) == 0)
                        fr_movequeue(tqe, tqe->tqe_ifq, tqtab + nstate, ifs);
        }

        return rval;
}


/* ------------------------------------------------------------------------ */
/* Function:    ipstate_log                                                 */
/* Returns:     Nil                                                         */
/* Parameters:  is(I)   - pointer to state structure                        */
/*              type(I) - type of log entry to create                       */
/*                                                                          */
/* Creates a state table log entry using the state structure and type info. */
/* passed in.  Log packet/byte counts, source/destination address and other */
/* protocol specific information.                                           */
/* ------------------------------------------------------------------------ */
void ipstate_log(is, type, ifs)
struct ipstate *is;
u_int type;
ipf_stack_t *ifs;
{
#ifdef  IPFILTER_LOG
        struct  ipslog  ipsl;
        size_t sizes[1];
        void *items[1];
        int types[1];

        /*
         * Copy information out of the ipstate_t structure and into the
         * structure used for logging.
         */
        ipsl.isl_type = type;
        ipsl.isl_pkts[0] = is->is_pkts[0] + is->is_icmppkts[0];
        ipsl.isl_bytes[0] = is->is_bytes[0];
        ipsl.isl_pkts[1] = is->is_pkts[1] + is->is_icmppkts[1];
        ipsl.isl_bytes[1] = is->is_bytes[1];
        ipsl.isl_pkts[2] = is->is_pkts[2] + is->is_icmppkts[2];
        ipsl.isl_bytes[2] = is->is_bytes[2];
        ipsl.isl_pkts[3] = is->is_pkts[3] + is->is_icmppkts[3];
        ipsl.isl_bytes[3] = is->is_bytes[3];
        ipsl.isl_src = is->is_src;
        ipsl.isl_dst = is->is_dst;
        ipsl.isl_p = is->is_p;
        ipsl.isl_v = is->is_v;
        ipsl.isl_flags = is->is_flags;
        ipsl.isl_tag = is->is_tag;
        ipsl.isl_rulen = is->is_rulen;
        (void) strncpy(ipsl.isl_group, is->is_group, FR_GROUPLEN);

        if (ipsl.isl_p == IPPROTO_TCP || ipsl.isl_p == IPPROTO_UDP) {
                ipsl.isl_sport = is->is_sport;
                ipsl.isl_dport = is->is_dport;
                if (ipsl.isl_p == IPPROTO_TCP) {
                        ipsl.isl_state[0] = is->is_state[0];
                        ipsl.isl_state[1] = is->is_state[1];
                }
        } else if (ipsl.isl_p == IPPROTO_ICMP) {
                ipsl.isl_itype = is->is_icmp.ici_type;
        } else if (ipsl.isl_p == IPPROTO_ICMPV6) {
                ipsl.isl_itype = is->is_icmp.ici_type;
        } else {
                ipsl.isl_ps.isl_filler[0] = 0;
                ipsl.isl_ps.isl_filler[1] = 0;
        }

        items[0] = &ipsl;
        sizes[0] = sizeof(ipsl);
        types[0] = 0;

        if (ipllog(IPL_LOGSTATE, NULL, items, sizes, types, 1, ifs)) {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_logged);
        } else {
                ATOMIC_INCL(ifs->ifs_ips_stats.iss_logfail);
        }
#endif
}


#ifdef  USE_INET6
/* ------------------------------------------------------------------------ */
/* Function:    fr_checkicmp6matchingstate                                  */
/* Returns:     ipstate_t* - NULL == no match found,                        */
/*                           else  pointer to matching state entry          */
/* Parameters:  fin(I) - pointer to packet information                      */
/* Locks:       NULL == no locks, else Read Lock on ipf_state               */
/*                                                                          */
/* If we've got an ICMPv6 error message, using the information stored in    */
/* the ICMPv6 packet, look for a matching state table entry.                */
/* ------------------------------------------------------------------------ */
static ipstate_t *fr_checkicmp6matchingstate(fin)
fr_info_t *fin;
{
        struct icmp6_hdr *ic6, *oic;
        int backward, i;
        ipstate_t *is, **isp;
        u_short sport, dport;
        i6addr_t dst, src;
        u_short savelen;
        icmpinfo_t *ic;
        fr_info_t ofin;
        tcphdr_t *tcp;
        ip6_t *oip6;
        u_char  pr;
        u_int hv;
        ipf_stack_t *ifs = fin->fin_ifs;

        /*
         * Does it at least have the return (basic) IP header ?
         * Is it an actual recognised ICMP error type?
         * Only a basic IP header (no options) should be with
         * an ICMP error header.
         */
        if ((fin->fin_v != 6) || (fin->fin_plen < ICMP6ERR_MINPKTLEN) ||
            !(fin->fin_flx & FI_ICMPERR))
                return NULL;

        ic6 = fin->fin_dp;

        oip6 = (ip6_t *)((char *)ic6 + ICMPERR_ICMPHLEN);
        if (fin->fin_plen < sizeof(*oip6))
                return NULL;

        bcopy((char *)fin, (char *)&ofin, sizeof(*fin));
        ofin.fin_v = 6;
        ofin.fin_ifp = fin->fin_ifp;
        ofin.fin_out = !fin->fin_out;
        ofin.fin_m = NULL;      /* if dereferenced, panic XXX */
        ofin.fin_mp = NULL;     /* if dereferenced, panic XXX */

        /*
         * We make a fin entry to be able to feed it to
         * matchsrcdst. Note that not all fields are necessary
         * but this is the cleanest way. Note further we fill
         * in fin_mp such that if someone uses it we'll get
         * a kernel panic. fr_matchsrcdst does not use this.
         *
         * watch out here, as ip is in host order and oip6 in network
         * order. Any change we make must be undone afterwards.
         */
        savelen = oip6->ip6_plen;
        oip6->ip6_plen = fin->fin_dlen - ICMPERR_ICMPHLEN;
        ofin.fin_flx = FI_NOCKSUM;
        ofin.fin_ip = (ip_t *)oip6;
        ofin.fin_plen = oip6->ip6_plen;
        (void) fr_makefrip(sizeof(*oip6), (ip_t *)oip6, &ofin);
        ofin.fin_flx &= ~(FI_BAD|FI_SHORT);
        oip6->ip6_plen = savelen;

        if (oip6->ip6_nxt == IPPROTO_ICMPV6) {
                oic = (struct icmp6_hdr *)(oip6 + 1);
                /*
                 * an ICMP error can only be generated as a result of an
                 * ICMP query, not as the response on an ICMP error
                 *
                 * XXX theoretically ICMP_ECHOREP and the other reply's are
                 * ICMP query's as well, but adding them here seems strange XXX
                 */
                 if (!(oic->icmp6_type & ICMP6_INFOMSG_MASK))
                        return NULL;

                /*
                 * perform a lookup of the ICMP packet in the state table
                 */
                hv = (pr = oip6->ip6_nxt);
                src.in6 = oip6->ip6_src;
                hv += src.in4.s_addr;
                dst.in6 = oip6->ip6_dst;
                hv += dst.in4.s_addr;
                hv += oic->icmp6_id;
                hv += oic->icmp6_seq;
                hv = DOUBLE_HASH(hv, ifs);

                READ_ENTER(&ifs->ifs_ipf_state);
                for (isp = &ifs->ifs_ips_table[hv]; ((is = *isp) != NULL); ) {
                        ic = &is->is_icmp;
                        isp = &is->is_hnext;
                        if ((is->is_p == pr) &&
                            !(is->is_pass & FR_NOICMPERR) &&
                            (oic->icmp6_id == ic->ici_id) &&
                            (oic->icmp6_seq == ic->ici_seq) &&
                            (is = fr_matchsrcdst(&ofin, is, &src,
                                                 &dst, NULL, FI_ICMPCMP))) {
                                /*
                                 * in the state table ICMP query's are stored
                                 * with the type of the corresponding ICMP
                                 * response. Correct here
                                 */
                                if (((ic->ici_type == ICMP6_ECHO_REPLY) &&
                                     (oic->icmp6_type == ICMP6_ECHO_REQUEST)) ||
                                     (ic->ici_type - 1 == oic->icmp6_type )) {
                                        ifs->ifs_ips_stats.iss_hits++;
                                        backward = IP6_NEQ(&is->is_dst, &src);
                                        fin->fin_rev = !backward;
                                        i = (backward << 1) + fin->fin_out;
                                        is->is_icmppkts[i]++;
                                        return is;
                                }
                        }
                }
                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                return NULL;
        }

        hv = (pr = oip6->ip6_nxt);
        src.in6 = oip6->ip6_src;
        hv += src.i6[0];
        hv += src.i6[1];
        hv += src.i6[2];
        hv += src.i6[3];
        dst.in6 = oip6->ip6_dst;
        hv += dst.i6[0];
        hv += dst.i6[1];
        hv += dst.i6[2];
        hv += dst.i6[3];

        if ((oip6->ip6_nxt == IPPROTO_TCP) || (oip6->ip6_nxt == IPPROTO_UDP)) {
                tcp = (tcphdr_t *)(oip6 + 1);
                dport = tcp->th_dport;
                sport = tcp->th_sport;
                hv += dport;
                hv += sport;
        } else
                tcp = NULL;
        hv = DOUBLE_HASH(hv, ifs);

        READ_ENTER(&ifs->ifs_ipf_state);
        for (isp = &ifs->ifs_ips_table[hv]; ((is = *isp) != NULL); ) {
                isp = &is->is_hnext;
                /*
                 * Only allow this icmp though if the
                 * encapsulated packet was allowed through the
                 * other way around. Note that the minimal amount
                 * of info present does not allow for checking against
                 * tcp internals such as seq and ack numbers.
                 */
                if ((is->is_p != pr) || (is->is_v != 6) ||
                    (is->is_pass & FR_NOICMPERR))
                        continue;
                is = fr_matchsrcdst(&ofin, is, &src, &dst, tcp, FI_ICMPCMP);
                if (is != NULL) {
                        ifs->ifs_ips_stats.iss_hits++;
                        backward = IP6_NEQ(&is->is_dst, &src);
                        fin->fin_rev = !backward;
                        i = (backward << 1) + fin->fin_out;
                        is->is_icmppkts[i]++;
                        /*
                         * we deliberately do not touch the timeouts
                         * for the accompanying state table entry.
                         * It remains to be seen if that is correct. XXX
                         */
                        return is;
                }
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_state);
        return NULL;
}
#endif


/* ------------------------------------------------------------------------ */
/* Function:    fr_sttab_init                                               */
/* Returns:     Nil                                                         */
/* Parameters:  tqp(I) - pointer to an array of timeout queues for TCP      */
/*                                                                          */
/* Initialise the array of timeout queues for TCP.                          */
/* ------------------------------------------------------------------------ */
void fr_sttab_init(tqp, ifs)
ipftq_t *tqp;
ipf_stack_t *ifs;
{
        int i;

        for (i = IPF_TCP_NSTATES - 1; i >= 0; i--) {
                tqp[i].ifq_ttl = 0;
                tqp[i].ifq_ref = 1;
                tqp[i].ifq_head = NULL;
                tqp[i].ifq_tail = &tqp[i].ifq_head;
                tqp[i].ifq_next = tqp + i + 1;
                MUTEX_INIT(&tqp[i].ifq_lock, "ipftq tcp tab");
        }
        tqp[IPF_TCP_NSTATES - 1].ifq_next = NULL;
        tqp[IPF_TCPS_CLOSED].ifq_ttl = ifs->ifs_fr_tcpclosed;
        tqp[IPF_TCPS_LISTEN].ifq_ttl = ifs->ifs_fr_tcptimeout;
        tqp[IPF_TCPS_SYN_SENT].ifq_ttl = ifs->ifs_fr_tcptimeout;
        tqp[IPF_TCPS_SYN_RECEIVED].ifq_ttl = ifs->ifs_fr_tcptimeout;
        tqp[IPF_TCPS_ESTABLISHED].ifq_ttl = ifs->ifs_fr_tcpidletimeout;
        tqp[IPF_TCPS_CLOSE_WAIT].ifq_ttl = ifs->ifs_fr_tcphalfclosed;
        tqp[IPF_TCPS_FIN_WAIT_1].ifq_ttl = ifs->ifs_fr_tcphalfclosed;
        tqp[IPF_TCPS_CLOSING].ifq_ttl = ifs->ifs_fr_tcptimeout;
        tqp[IPF_TCPS_LAST_ACK].ifq_ttl = ifs->ifs_fr_tcplastack;
        tqp[IPF_TCPS_FIN_WAIT_2].ifq_ttl = ifs->ifs_fr_tcpclosewait;
        tqp[IPF_TCPS_TIME_WAIT].ifq_ttl = ifs->ifs_fr_tcptimeout;
        tqp[IPF_TCPS_HALF_ESTAB].ifq_ttl = ifs->ifs_fr_tcptimeout;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_sttab_destroy                                            */
/* Returns:     Nil                                                         */
/* Parameters:  tqp(I) - pointer to an array of timeout queues for TCP      */
/*                                                                          */
/* Do whatever is necessary to "destroy" each of the entries in the array   */
/* of timeout queues for TCP.                                               */
/* ------------------------------------------------------------------------ */
void fr_sttab_destroy(tqp)
ipftq_t *tqp;
{
        int i;

        for (i = IPF_TCP_NSTATES - 1; i >= 0; i--)
                MUTEX_DESTROY(&tqp[i].ifq_lock);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_statederef                                               */
/* Returns:     Nil                                                         */
/* Parameters:  isp(I) - pointer to pointer to state table entry            */
/*              ifs - ipf stack instance                                    */
/*                                                                          */
/* Decrement the reference counter for this state table entry and free it   */
/* if there are no more things using it.                                    */
/*                                                                          */
/* Internal parameters:                                                     */
/*    state[0] = state of source (host that initiated connection)           */
/*    state[1] = state of dest   (host that accepted the connection)        */
/* ------------------------------------------------------------------------ */
void fr_statederef(isp, ifs)
ipstate_t **isp;
ipf_stack_t *ifs;
{
        ipstate_t *is;

        is = *isp;
        *isp = NULL;

        MUTEX_ENTER(&is->is_lock);
        if (is->is_ref > 1) {
                is->is_ref--;
                MUTEX_EXIT(&is->is_lock);
#ifndef _KERNEL
                if ((is->is_sti.tqe_state[0] > IPF_TCPS_ESTABLISHED) ||
                   (is->is_sti.tqe_state[1] > IPF_TCPS_ESTABLISHED)) {
                        (void) fr_delstate(is, ISL_ORPHAN, ifs);
                }
#endif
                return;
        }
        MUTEX_EXIT(&is->is_lock);

        WRITE_ENTER(&ifs->ifs_ipf_state);
        (void) fr_delstate(is, ISL_EXPIRE, ifs);
        RWLOCK_EXIT(&ifs->ifs_ipf_state);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_setstatequeue                                            */
/* Returns:     Nil                                                         */
/* Parameters:  is(I) - pointer to state structure                          */
/*              rev(I) - forward(0) or reverse(1) direction                 */
/* Locks:       ipf_state (read or write)                                   */
/*                                                                          */
/* Put the state entry on its default queue entry, using rev as a helped in */
/* determining which queue it should be placed on.                          */
/* ------------------------------------------------------------------------ */
void fr_setstatequeue(is, rev, ifs)
ipstate_t *is;
int rev;
ipf_stack_t *ifs;
{
        ipftq_t *oifq, *nifq;


        if ((is->is_sti.tqe_flags & TQE_RULEBASED) != 0)
                nifq = is->is_tqehead[rev];
        else
                nifq = NULL;

        if (nifq == NULL) {
                switch (is->is_p)
                {
#ifdef USE_INET6
                case IPPROTO_ICMPV6 :
                        if (rev == 1)
                                nifq = &ifs->ifs_ips_icmpacktq;
                        else
                                nifq = &ifs->ifs_ips_icmptq;
                        break;
#endif
                case IPPROTO_ICMP :
                        if (rev == 1)
                                nifq = &ifs->ifs_ips_icmpacktq;
                        else
                                nifq = &ifs->ifs_ips_icmptq;
                        break;
                case IPPROTO_TCP :
                        nifq = ifs->ifs_ips_tqtqb + is->is_state[rev];
                        break;

                case IPPROTO_UDP :
                        if (rev == 1)
                                nifq = &ifs->ifs_ips_udpacktq;
                        else
                                nifq = &ifs->ifs_ips_udptq;
                        break;

                default :
                        nifq = &ifs->ifs_ips_iptq;
                        break;
                }
        }

        oifq = is->is_sti.tqe_ifq;
        /*
         * If it's currently on a timeout queue, move it from one queue to
         * another, else put it on the end of the newly determined queue.
         */
        if (oifq != NULL)
                fr_movequeue(&is->is_sti, oifq, nifq, ifs);
        else
                fr_queueappend(&is->is_sti, nifq, is, ifs);
        return;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stateiter                                                */
/* Returns:     int - 0 == success, else error                              */
/* Parameters:  token(I) - pointer to ipftoken structure                    */
/*              itp(I)   - pointer to ipfgeniter structure                  */
/*                                                                          */
/* This function handles the SIOCGENITER ioctl for the state tables and     */
/* walks through the list of entries in the state table list (ips_list.)    */
/* ------------------------------------------------------------------------ */
static int fr_stateiter(token, itp, ifs)
ipftoken_t *token;
ipfgeniter_t *itp;
ipf_stack_t *ifs;
{
        ipstate_t *is, *next, zero;
        int error, count;
        char *dst;

        if (itp->igi_data == NULL)
                return EFAULT;

        if (itp->igi_nitems == 0)
                return EINVAL;

        if (itp->igi_type != IPFGENITER_STATE)
                return EINVAL;

        error = 0;

        READ_ENTER(&ifs->ifs_ipf_state);

        /*
         * Get "previous" entry from the token and find the next entry.
         */
        is = token->ipt_data;
        if (is == NULL) {
                next = ifs->ifs_ips_list;
        } else {
                next = is->is_next;
        }

        dst = itp->igi_data;
        for (count = itp->igi_nitems; count > 0; count--) {
                /*
                 * If we found an entry, add a reference to it and update the token.
                 * Otherwise, zero out data to be returned and NULL out token.
                 */
                if (next != NULL) {
                        MUTEX_ENTER(&next->is_lock);
                        next->is_ref++;
                        MUTEX_EXIT(&next->is_lock);
                        token->ipt_data = next;
                } else {
                        bzero(&zero, sizeof(zero));
                        next = &zero;
                        token->ipt_data = NULL;
                }

                /*
                 * Safe to release lock now the we have a reference.
                 */
                RWLOCK_EXIT(&ifs->ifs_ipf_state);

                /*
                 * Copy out data and clean up references and tokens.
                 */
                error = COPYOUT(next, dst, sizeof(*next));
                if (error != 0)
                        error = EFAULT;
                if (token->ipt_data == NULL) {
                        ipf_freetoken(token, ifs);
                        break;
                } else {
                        if (is != NULL)
                                fr_statederef(&is, ifs);
                        if (next->is_next == NULL) {
                                ipf_freetoken(token, ifs);
                                break;
                        }
                }

                if ((count == 1) || (error != 0))
                        break;

                READ_ENTER(&ifs->ifs_ipf_state);
                dst += sizeof(*next);
                is = next;
                next = is->is_next;
        }

        return error;
}