Logo Search packages:      
Sourcecode: kfreebsd-7 version File versions  Download package

ip_state.c

/*    $FreeBSD: src/sys/contrib/ipfilter/netinet/ip_state.c,v 1.39.2.1 2007/10/31 05:00:38 darrenr Exp $    */

/*
 * Copyright (C) 1995-2003 by Darren Reed.
 *
 * See the IPFILTER.LICENCE file for details on licencing.
 */
#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)
# if (__NetBSD_Version__ < 399001400)
#  include "opt_ipfilter_log.h"
# else
#  include "opt_ipfilter.h"
# endif
#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"
#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 2.186.2.80 2007/10/16 09:33:23 darrenr Exp $";
#endif

static      ipstate_t **ips_table = NULL;
static      u_long      *ips_seed = NULL;
static      int   ips_num = 0;
static      u_long ips_last_force_flush = 0;
ips_stat_t ips_stats;

#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));
static int fr_state_flush_entry __P((void *));
static ips_stat_t *fr_statetstats __P((void));
static int fr_delstate __P((ipstate_t *, int));
static int fr_state_remove __P((caddr_t));
static void fr_ipsmove __P((ipstate_t *, u_int));
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 *));
static int fr_stgettable __P((char *));

int fr_stputent __P((caddr_t));
int fr_stgetent __P((caddr_t));

#define     ONE_DAY           IPF_TTLVAL(1 * 86400)   /* 1 day */
#define     FIVE_DAYS   (5 * ONE_DAY)
#define     DOUBLE_HASH(x)    (((x) + ips_seed[(x) % fr_statesize]) % fr_statesize)

u_long      fr_tcpidletimeout = FIVE_DAYS,
      fr_tcpclosewait = IPF_TTLVAL(2 * TCP_MSL),
      fr_tcplastack = IPF_TTLVAL(30),
      fr_tcptimeout = IPF_TTLVAL(2 * TCP_MSL),
      fr_tcptimewait = IPF_TTLVAL(2 * TCP_MSL),
      fr_tcpclosed = IPF_TTLVAL(30),
      fr_tcphalfclosed = IPF_TTLVAL(2 * 3600),  /* 2 hours */
      fr_udptimeout = IPF_TTLVAL(120),
      fr_udpacktimeout = IPF_TTLVAL(12),
      fr_icmptimeout = IPF_TTLVAL(60),
      fr_icmpacktimeout = IPF_TTLVAL(6),
      fr_iptimeout = IPF_TTLVAL(60);
int   fr_statemax = IPSTATE_MAX,
      fr_statesize = IPSTATE_SIZE;
int   fr_state_doflush = 0,
      fr_state_lock = 0,
      fr_state_maxbucket = 0,
      fr_state_maxbucket_reset = 1,
      fr_state_init = 0;
ipftq_t     ips_tqtqb[IPF_TCP_NSTATES],
      ips_udptq,
      ips_udpacktq,
      ips_iptq,
      ips_icmptq,
      ips_icmpacktq,
      ips_deletetq,
      *ips_utqe = NULL;
#ifdef      IPFILTER_LOG
int   ipstate_logging = 1;
#else
int   ipstate_logging = 0;
#endif
ipstate_t *ips_list = NULL;


/* ------------------------------------------------------------------------ */
/* Function:    fr_stateinit                                                */
/* Returns:     int - 0 == success, -1 == failure                           */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Initialise all the global variables used within the state code.          */
/* This action also includes initiailising locks.                           */
/* ------------------------------------------------------------------------ */
int fr_stateinit()
{
      int i;

      KMALLOCS(ips_table, ipstate_t **, fr_statesize * sizeof(ipstate_t *));
      if (ips_table == NULL)
            return -1;
      bzero((char *)ips_table, fr_statesize * sizeof(ipstate_t *));

      KMALLOCS(ips_seed, u_long *, fr_statesize * sizeof(*ips_seed));
      if (ips_seed == NULL)
            return -2;
      for (i = 0; i < fr_statesize; i++) {
            /*
             * XXX - ips_seed[X] should be a random number of sorts.
             */
#if  (__FreeBSD_version >= 400000)
            ips_seed[i] = arc4random();
#else
            ips_seed[i] = ((u_long)ips_seed + i) * fr_statesize;
            ips_seed[i] ^= 0xa5a55a5a;
            ips_seed[i] *= (u_long)ips_seed;
            ips_seed[i] ^= 0x5a5aa5a5;
            ips_seed[i] *= 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(ips_stats.iss_bucketlen, u_long *,
             fr_statesize * sizeof(u_long));
      if (ips_stats.iss_bucketlen == NULL)
            return -1;
      bzero((char *)ips_stats.iss_bucketlen, fr_statesize * sizeof(u_long));

      if (fr_state_maxbucket == 0) {
            for (i = fr_statesize; i > 0; i >>= 1)
                  fr_state_maxbucket++;
            fr_state_maxbucket *= 2;
      }

      ips_stats.iss_tcptab = ips_tqtqb;
      fr_sttab_init(ips_tqtqb);
      ips_tqtqb[IPF_TCP_NSTATES - 1].ifq_next = &ips_udptq;
      ips_udptq.ifq_ttl = (u_long)fr_udptimeout;
      ips_udptq.ifq_ref = 1;
      ips_udptq.ifq_head = NULL;
      ips_udptq.ifq_tail = &ips_udptq.ifq_head;
      MUTEX_INIT(&ips_udptq.ifq_lock, "ipftq udp tab");
      ips_udptq.ifq_next = &ips_udpacktq;
      ips_udpacktq.ifq_ttl = (u_long)fr_udpacktimeout;
      ips_udpacktq.ifq_ref = 1;
      ips_udpacktq.ifq_head = NULL;
      ips_udpacktq.ifq_tail = &ips_udpacktq.ifq_head;
      MUTEX_INIT(&ips_udpacktq.ifq_lock, "ipftq udpack tab");
      ips_udpacktq.ifq_next = &ips_icmptq;
      ips_icmptq.ifq_ttl = (u_long)fr_icmptimeout;
      ips_icmptq.ifq_ref = 1;
      ips_icmptq.ifq_head = NULL;
      ips_icmptq.ifq_tail = &ips_icmptq.ifq_head;
      MUTEX_INIT(&ips_icmptq.ifq_lock, "ipftq icmp tab");
      ips_icmptq.ifq_next = &ips_icmpacktq;
      ips_icmpacktq.ifq_ttl = (u_long)fr_icmpacktimeout;
      ips_icmpacktq.ifq_ref = 1;
      ips_icmpacktq.ifq_head = NULL;
      ips_icmpacktq.ifq_tail = &ips_icmpacktq.ifq_head;
      MUTEX_INIT(&ips_icmpacktq.ifq_lock, "ipftq icmpack tab");
      ips_icmpacktq.ifq_next = &ips_iptq;
      ips_iptq.ifq_ttl = (u_long)fr_iptimeout;
      ips_iptq.ifq_ref = 1;
      ips_iptq.ifq_head = NULL;
      ips_iptq.ifq_tail = &ips_iptq.ifq_head;
      MUTEX_INIT(&ips_iptq.ifq_lock, "ipftq ip tab");
      ips_iptq.ifq_next = &ips_deletetq;
      ips_deletetq.ifq_ttl = (u_long)1;
      ips_deletetq.ifq_ref = 1;
      ips_deletetq.ifq_head = NULL;
      ips_deletetq.ifq_tail = &ips_deletetq.ifq_head;
      MUTEX_INIT(&ips_deletetq.ifq_lock, "state delete queue");
      ips_deletetq.ifq_next = NULL;

      RWLOCK_INIT(&ipf_state, "ipf IP state rwlock");
      MUTEX_INIT(&ipf_stinsert, "ipf state insert mutex");
      fr_state_init = 1;

      ips_last_force_flush = fr_ticks;
      return 0;
}


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

      while ((is = ips_list) != NULL)
            fr_delstate(is, ISL_UNLOAD);

      /*
       * 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 = ips_utqe; ifq != NULL; ifq = ifqnext) {
            ifqnext = ifq->ifq_next;
            if (((ifq->ifq_flags & IFQF_PROXY) == 0) &&
                (fr_deletetimeoutqueue(ifq) == 0))
                  fr_freetimeoutqueue(ifq);
      }

      ips_stats.iss_inuse = 0;
      ips_num = 0;

      if (fr_state_init == 1) {
            fr_sttab_destroy(ips_tqtqb);
            MUTEX_DESTROY(&ips_udptq.ifq_lock);
            MUTEX_DESTROY(&ips_icmptq.ifq_lock);
            MUTEX_DESTROY(&ips_udpacktq.ifq_lock);
            MUTEX_DESTROY(&ips_icmpacktq.ifq_lock);
            MUTEX_DESTROY(&ips_iptq.ifq_lock);
            MUTEX_DESTROY(&ips_deletetq.ifq_lock);
      }

      if (ips_table != NULL) {
            KFREES(ips_table, fr_statesize * sizeof(*ips_table));
            ips_table = NULL;
      }

      if (ips_seed != NULL) {
            KFREES(ips_seed, fr_statesize * sizeof(*ips_seed));
            ips_seed = NULL;
      }

      if (ips_stats.iss_bucketlen != NULL) {
            KFREES(ips_stats.iss_bucketlen, fr_statesize * sizeof(u_long));
            ips_stats.iss_bucketlen = NULL;
      }

      if (fr_state_maxbucket_reset == 1)
            fr_state_maxbucket = 0;

      if (fr_state_init == 1) {
            fr_state_init = 0;
            RW_DESTROY(&ipf_state);
            MUTEX_DESTROY(&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()
{
      ips_stats.iss_active = ips_num;
      ips_stats.iss_statesize = fr_statesize;
      ips_stats.iss_statemax = fr_statemax;
      ips_stats.iss_table = ips_table;
      ips_stats.iss_list = ips_list;
      ips_stats.iss_ticks = fr_ticks;
      return &ips_stats;
}

/* ------------------------------------------------------------------------ */
/* Function:    fr_state_remove                                             */
/* Returns:     int - 0 == success, != 0 == failure                         */
/* Parameters:  data(I) - pointer to state structure to delete from table   */
/*                                                                          */
/* 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)
caddr_t data;
{
      ipstate_t *sp, st;
      int error;

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

      WRITE_ENTER(&ipf_state);
      for (sp = 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_src,
                    sizeof(st.is_dst)) &&
                !bcmp((caddr_t)&sp->is_ps, (caddr_t)&st.is_ps,
                    sizeof(st.is_ps))) {
                  fr_delstate(sp, ISL_REMOVE);
                  RWLOCK_EXIT(&ipf_state);
                  return 0;
            }
      RWLOCK_EXIT(&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                     */
/*                                                                          */
/* Processes an ioctl call made to operate on the IP Filter state device.   */
/* ------------------------------------------------------------------------ */
int fr_state_ioctl(data, cmd, mode, uid, ctx)
caddr_t data;
ioctlcmd_t cmd;
int mode, uid;
void *ctx;
{
      int arg, ret, error = 0;
      SPL_INT(s);

      switch (cmd)
      {
      /*
       * Delete an entry from the state table.
       */
      case SIOCDELST :
            error = fr_state_remove(data);
            break;

      /*
       * Flush the state table
       */
      case SIOCIPFFL :
            error = BCOPYIN(data, (char *)&arg, sizeof(arg));
            if (error != 0) {
                  error = EFAULT;
            } else {
                  WRITE_ENTER(&ipf_state);
                  ret = fr_state_flush(arg, 4);
                  RWLOCK_EXIT(&ipf_state);
                  error = BCOPYOUT((char *)&ret, data, sizeof(ret));
                  if (error != 0)
                        error = EFAULT;
            }
            break;

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

                  tmp = ipflog_clear(IPL_LOGSTATE);
                  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 *)&ipstate_logging,
                              sizeof(ipstate_logging));
                  if (error != 0)
                        error = EFAULT;
            }
            break;

      /*
       * Return the current state of logging.
       */
      case SIOCGETLG :
            error = BCOPYOUT((char *)&ipstate_logging, (char *)data,
                         sizeof(ipstate_logging));
            if (error != 0)
                  error = EFAULT;
            break;

      /*
       * Return the number of bytes currently waiting to be read.
       */
      case FIONREAD :
            arg = 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(), 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, &fr_state_lock);
            }
            break;

      /*
       * Add an entry to the current state table.
       */
      case SIOCSTPUT :
            if (!fr_state_lock || !(mode &FWRITE)) {
                  error = EACCES;
                  break;
            }
            error = fr_stputent(data);
            break;

      /*
       * Get a state table entry.
       */
      case SIOCSTGET :
            if (!fr_state_lock) {
                  error = EACCES;
                  break;
            }
            error = fr_stgetent(data);
            break;

      /*
       * Return a copy of the hash table bucket lengths
       */
      case SIOCSTAT1 :
            error = BCOPYOUT(ips_stats.iss_bucketlen, data,
                         fr_statesize * sizeof(u_long));
            if (error != 0)
                  error = EFAULT;
            break;

      case SIOCGENITER :
          {
            ipftoken_t *token;
            ipfgeniter_t iter;

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

            SPL_SCHED(s);
            token = ipf_findtoken(IPFGENITER_STATE, uid, ctx);
            if (token != NULL)
                  error = fr_stateiter(token, &iter);
            else
                  error = ESRCH;
            RWLOCK_EXIT(&ipf_tokens);
            SPL_X(s);
            break;
          }

      case SIOCGTABL :
            error = fr_stgettable(data);
            break;

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

      case SIOCGTQTAB :
            error = fr_outobj(data, ips_tqtqb, IPFOBJ_STATETQTAB);
            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)
caddr_t data;
{
      ipstate_t *is, *isn;
      ipstate_save_t ips;
      int error;

      error = fr_inobj(data, &ips, IPFOBJ_STATESAVE);
      if (error != 0)
            return error;

      isn = ips.ips_next;
      if (isn == NULL) {
            isn = 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 = 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);
      return error;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stputent                                                 */
/* Returns:     int - 0 == success, != 0 == failure                         */
/* Parameters:  data(I) - pointer to state information struct               */
/*                                                                          */
/* 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)
caddr_t data;
{
      ipstate_t *is, *isn;
      ipstate_save_t ips;
      int error, out, i;
      frentry_t *fr;
      char *name;

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

      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(&ipf_state);
            fr_stinsert(isn, 0);
            MUTEX_EXIT(&isn->is_lock);
            RWLOCK_EXIT(&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));
            out = fr->fr_flags & FR_OUTQUE ? 1 : 0;
            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);
                  name = isn->is_ifname[i];
                  isn->is_ifp[i] = fr_resolvenic(name, isn->is_v);
            }

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

            fr_resolvedest(&fr->fr_tifs[0], fr->fr_v);
            fr_resolvedest(&fr->fr_tifs[1], fr->fr_v);
            fr_resolvedest(&fr->fr_dif, fr->fr_v);

            /*
             * 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(&ipf_state);
            fr_stinsert(isn, 0);
            MUTEX_EXIT(&isn->is_lock);
            RWLOCK_EXIT(&ipf_state);

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

            if (is == NULL) {
                  KFREE(isn);
                  isn = NULL;
            }
            RWLOCK_EXIT(&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)
ipstate_t *is;
int rev;
{
      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);
      }

      /*
       * 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 % 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(&ipf_stinsert);

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

      if (ips_table[hv] != NULL)
            ips_table[hv]->is_phnext = &is->is_hnext;
      else
            ips_stats.iss_inuse++;
      is->is_phnext = ips_table + hv;
      is->is_hnext = ips_table[hv];
      ips_table[hv] = is;
      ips_stats.iss_bucketlen[hv]++;
      ips_num++;
      MUTEX_EXIT(&ipf_stinsert);

      fr_setstatequeue(is, rev);
}


/* ------------------------------------------------------------------------ */
/* 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.   */
/*                                                                          */
/* NOTE: The use of stsave to point to nat_state will result in memory      */
/*       corruption.  It should only be used to point to objects that will  */
/*       either outlive this (not expired) or will deref the ip_state_t     */
/*       when they are deleted.                                             */
/* ------------------------------------------------------------------------ */
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;
      int out;

      if (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;

      /*
       * If a "keep state" rule has reached the maximum number of references
       * to it, then schedule an automatic flush in case we can clear out
       * some "dead old wood".  Note that because the lock isn't held on
       * fr it is possible that we could overflow.  The cost of overflowing
       * is being ignored here as the number by which it can overflow 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.
       */
      fr = fin->fin_fr;
      if (fr != NULL) {
            if ((ips_num >= fr_statemax) && (fr->fr_statemax == 0)) {
                  ATOMIC_INCL(ips_stats.iss_max);
                  fr_state_doflush = 1;
                  return NULL;
            }
            if ((fr->fr_statemax != 0) &&
                (fr->fr_statecnt >= fr->fr_statemax)) {
                  ATOMIC_INCL(ips_stats.iss_maxref);
                  return NULL;
            }
      }

      pass = (fr == NULL) ? 0 : fr->fr_flags;

      ic = NULL;
      tcp = NULL;
      out = fin->fin_out;
      is = &ips;
      bzero((char *)is, sizeof(*is));
      is->is_die = 1 + fr_ticks;

      /*
       * 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...
                   */
                  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(ips_stats.iss_icmp);
            break;
#endif
      case IPPROTO_ICMP :
            ic = fin->fin_dp;

            switch (ic->icmp_type)
            {
            case ICMP_ECHO :
            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(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(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(ips_stats.iss_udp);
            break;

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

      /*
       * Look for identical state.
       */
      for (is = ips_table[is->is_hv % fr_statesize]; is != NULL;
           is = is->is_hnext) {
            if (bcmp(&ips.is_src, &is->is_src,
                   offsetof(struct ipstate, is_ps) -
                   offsetof(struct ipstate, is_src)) == 0)
                  break;
      }
      if (is != NULL)
            return NULL;

      if (ips_stats.iss_bucketlen[hv] >= fr_state_maxbucket) {
            ATOMIC_INCL(ips_stats.iss_bucketfull);
            return NULL;
      }
      KMALLOC(is, ipstate_t *);
      if (is == NULL) {
            ATOMIC_INCL(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(&ips_utqe,
                                                 fr->fr_age[0]);
                  is->is_sti.tqe_flags |= TQE_RULEBASED;
            }
            if (fr->fr_age[1] != 0) {
                  is->is_tqehead[1] = fr_addtimeoutqueue(&ips_utqe,
                                                 fr->fr_age[1]);
                  is->is_sti.tqe_flags |= TQE_RULEBASED;
            }

            is->is_tag = fr->fr_logtag;

            /*
             * The name '-' is special for network interfaces and causes
             * a NULL name to be present, always, allowing packets to
             * match it, regardless of their interface.
             */
            if ((fin->fin_ifp == NULL) ||
                (fr->fr_ifnames[out << 1][0] == '-' &&
                 fr->fr_ifnames[out << 1][1] == '\0')) {
                  is->is_ifp[out << 1] = fr->fr_ifas[0];
                  strncpy(is->is_ifname[out << 1], fr->fr_ifnames[0],
                        sizeof(fr->fr_ifnames[0]));
            } else {
                  is->is_ifp[out << 1] = fin->fin_ifp;
                  COPYIFNAME(is->is_v, fin->fin_ifp,
                           is->is_ifname[out << 1]);
            }

            is->is_ifp[(out << 1) + 1] = fr->fr_ifas[1];
            strncpy(is->is_ifname[(out << 1) + 1], fr->fr_ifnames[1],
                  sizeof(fr->fr_ifnames[1]));

            is->is_ifp[(1 - out) << 1] = fr->fr_ifas[2];
            strncpy(is->is_ifname[((1 - out) << 1)], fr->fr_ifnames[2],
                  sizeof(fr->fr_ifnames[2]));

            is->is_ifp[((1 - out) << 1) + 1] = fr->fr_ifas[3];
            strncpy(is->is_ifname[((1 - out) << 1) + 1], fr->fr_ifnames[3],
                  sizeof(fr->fr_ifnames[3]));
      } else {
            pass = fr_flags;
            is->is_tag = FR_NOLOGTAG;

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

      /*
       * It may seem strange to set is_ref to 2, but fr_check() will call
       * fr_statederef() after calling fr_addstate() and the idea is to
       * have it exist at the end of fr_check() with is_ref == 1.
       */
      is->is_ref = 2;
      is->is_pass = pass;
      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;

      /*
       * 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_v = fin->fin_v;
      is->is_opt[0] = fin->fin_optmsk;
      is->is_optmsk[0] = 0xffffffff;
      is->is_optmsk[1] = 0xffffffff;
      if (is->is_v == 6) {
            is->is_opt[0] &= ~0x8;
            is->is_optmsk[0] &= ~0x8;
            is->is_optmsk[1] &= ~0x8;
      }
      is->is_me = stsave;
      is->is_sec = fin->fin_secmsk;
      is->is_secmsk = 0xffff;
      is->is_auth = fin->fin_auth;
      is->is_authmsk = 0xffff;
      if (flags & (SI_WILDP|SI_WILDA)) {
            ATOMIC_INCL(ips_stats.iss_wild);
      }
      is->is_rulen = fin->fin_rule;


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

      READ_ENTER(&ipf_state);

      fr_stinsert(is, fin->fin_rev);

      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, 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 (ipstate_logging)
            ipstate_log(is, ISL_NEW);

      RWLOCK_EXIT(&ipf_state);
      fin->fin_state = is;
      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,    */
/*                   -1 == packet has bad TCP options data                  */
/* 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;

      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 on the way out
       * but hasn't yet departed then advance this session along the way.
       */
      if ((tcp->th_flags & TH_OPENING) == TH_SYN) {
            if ((is->is_state[0] > IPF_TCPS_ESTABLISHED) &&
                (is->is_state[1] > IPF_TCPS_ESTABLISHED)) {
                  is->is_state[!source] = IPF_TCPS_CLOSED;
                  fr_movequeue(&is->is_sti, is->is_sti.tqe_ifq,
                             &ips_deletetq);
                  MUTEX_EXIT(&is->is_lock);
                  return 0;
            }
      }

      ret = fr_tcpinwindow(fin, fdata, tdata, tcp, is->is_flags);
      if (ret > 0) {
#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, 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))) {
                        if (fr_tcpoptions(fin, tcp, fdata) == -1)
                              fin->fin_flx |= FI_BAD;
                  }
                  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))) {
                        if (fr_tcpoptions(fin, tcp, fdata) == -1)
                              fin->fin_flx |= FI_BAD;
                  }

                  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,     */
/*                    2 == packet seq number matches next expected          */
/* 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;

      /*
       * A window of 0 produces undesirable behaviour from this function.
       */
      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 (seq != fdata->td_end) {
            if ((flags & IS_STRICT) != 0) {
                  return 0;
            }
      }

      inseq = 0;
      if ((SEQ_GE(fdata->td_maxend, end)) &&
          (SEQ_GE(seq, fdata->td_end - maxwin)) &&
/* 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;
      /*
       * Sometimes a TCP RST will be generated with only the ACK field
       * set to non-zero.
       */
      } else if ((seq == 0) && (tcpflags == (TH_RST|TH_ACK)) &&
               (ackskew >= -1) && (ackskew <= 1)) {
            inseq = 1;
      } else if (!(flags & IS_TCPFSM)) {
            int i;

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

#if 0
            if (is_pkts[i]0 == 0) {
                  /*
                   * Picking up a connection in the middle, the "next"
                   * packet seen from a direction that is new should be
                   * accepted, even if it appears out of sequence.
                   */
                  inseq = 1;
            } else 
#endif
            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;
            }
      }

      /* TRACE(inseq, fdata, tdata, seq, end, ack, ackskew, win, maxwin) */

      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)
                  tdata->td_end = ack;

            /* update max window seen */
            if (fdata->td_maxwin < win)
                  fdata->td_maxwin = win;
            if (SEQ_GT(end, fdata->td_end))
                  fdata->td_end = end;
            if (SEQ_GE(ack + win, tdata->td_maxend))
                  tdata->td_maxend = ack + win;
            return 1;
      }
      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;

      if (ips_num == fr_statemax) {
            ATOMIC_INCL(ips_stats.iss_max);
            fr_state_doflush = 1;
            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 + 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);
      clone->is_ref = 2;
      if (clone->is_p == IPPROTO_TCP) {
            (void) fr_tcp_age(&clone->is_sti, fin, 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;

      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] == ifp) || (is->is_ifp[idx] == NULL &&
          (*is->is_ifname[idx] == '\0' || *is->is_ifname[idx] == '-' ||
           *is->is_ifname[idx] == '*')))
            ret = 1;

      if (ret == 0)
            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)
            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(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))
            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(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) && ipstate_logging)
                  ipstate_log(is, ISL_CLONE);
      }

      ret = -1;

      if (is->is_flx[out][rev] == 0) {
            is->is_flx[out][rev] = flx;
            is->is_opt[rev] = fin->fin_optmsk;
            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(is->is_v, ifp, is->is_ifname[idx]);
      }
      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 type, len;
      ip_t *oip;
      u_int hv;

      /*
       * 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;
      type = ic->icmp_type;

      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 */
      (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);

            READ_ENTER(&ipf_state);
            for (isp = &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) {
                        /*
                         * 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;
                        ips_stats.iss_hits++;
                        is->is_icmppkts[i]++;
                        return is;
                  }
            }
            RWLOCK_EXIT(&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);

      READ_ENTER(&ipf_state);
      for (isp = &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;
                  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(&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)
ipstate_t *is;
u_int hv;
{
      ipstate_t **isp;
      u_int hvm;

      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 (ips_table[hvm] == NULL)
            ips_stats.iss_inuse--;
      ips_stats.iss_bucketlen[hvm]--;

      /*
       * ...and put the hash in the new one.
       */
      hvm = DOUBLE_HASH(hv);
      is->is_hv = hvm;
      isp = &ips_table[hvm];
      if (*isp)
            (*isp)->is_phnext = &is->is_hnext;
      else
            ips_stats.iss_inuse++;
      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;

      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(&ipf_state);
icmp6again:
            hvm = DOUBLE_HASH(hv);
            for (isp = &ips_table[hvm]; ((is = *isp) != NULL); ) {
                  isp = &is->is_hnext;
                  /*
                   * If a connection is about to be deleted, no packets
                   * are allowed to match it.
                   */
                  if (is->is_sti.tqe_ifq == &ips_deletetq)
                        continue;

                  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 = &ips_icmpacktq;
                        else
                              ifq = &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);
                        MUTEX_DOWNGRADE(&ipf_state);
                  }
                  break;
            }
            RWLOCK_EXIT(&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 ((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(&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);
            READ_ENTER(&ipf_state);
            for (isp = &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) &&
                      (ic->icmp_id == is->is_icmp.ici_id) &&
                      fr_matchicmpqueryreply(v, &is->is_icmp,
                                       ic, fin->fin_rev)) {
                        if (fin->fin_rev)
                              ifq = &ips_icmpacktq;
                        else
                              ifq = &ips_icmptq;
                        break;
                  }
            }
            if (is == NULL) {
                  RWLOCK_EXIT(&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(&ipf_state);
retry_tcpudp:
            hvm = DOUBLE_HASH(hv);
            for (isp = &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);
                        MUTEX_DOWNGRADE(&ipf_state);
                  }
                  break;
            }
            RWLOCK_EXIT(&ipf_state);

            if (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(&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);
            READ_ENTER(&ipf_state);
            for (isp = &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 = &ips_iptq;
                        break;
                  }
            }
            if (is == NULL) {
                  RWLOCK_EXIT(&ipf_state);
            }
            break;
      }

      if (is != NULL) {
            if (((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;

      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);

      is->is_pkts[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(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;

      if (fr_state_lock || (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 = fin->fin_state;
      if (is == 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 = &ips_udpacktq;
            else
                  ifq = &ips_udptq;
            break;
      }
      if (is == NULL) {
            ATOMIC_INCL(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)
                        return NULL;
                  if (fr_matchtag(&fr->fr_nattag, fin->fin_nattag) != 0)
                        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);

      fin->fin_state = is;
      is->is_touched = fr_ticks;
      MUTEX_ENTER(&is->is_lock);
      is->is_ref++;
      MUTEX_EXIT(&is->is_lock);
      RWLOCK_EXIT(&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(fin, &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(fin, &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(fin, &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(fin, &tcp->th_sum, is->is_sumd[1]);
            }
      }
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_statesync                                                */
/* Returns:     Nil                                                         */
/* Parameters:  ifp(I) - pointer to interface                               */
/*                                                                          */
/* 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(ifp)
void *ifp;
{
      ipstate_t *is;
      int i;

      if (fr_running <= 0)
            return;

      WRITE_ENTER(&ipf_state);

      if (fr_running <= 0) {
            RWLOCK_EXIT(&ipf_state);
            return;
      }

      for (is = ips_list; is; is = is->is_next) {
            /*
             * Look up all the interface names in the state entry.
             */
            for (i = 0; i < 4; i++) {
                  if (ifp == NULL || ifp == is->is_ifp[i])
                        is->is_ifp[i] = fr_resolvenic(is->is_ifname[i],
                                                is->is_v);
            }
      }
      RWLOCK_EXIT(&ipf_state);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_delstate                                                 */
/* Returns:     int - 0 = entry deleted, else reference count on struct     */
/* Parameters:  is(I)  - pointer to state structure to delete               */
/*              why(I) - if not 0, log reason why it was deleted            */
/* Write Locks: ipf_state                                                   */
/*                                                                          */
/* 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.                                             */
/* ------------------------------------------------------------------------ */
static int fr_delstate(is, why)
ipstate_t *is;
int why;
{

      /*
       * Since we want to delete this, remove it from the state table,
       * where it can be found & used, first.
       */
      if (is->is_phnext != NULL) {
            *is->is_phnext = is->is_hnext;
            if (is->is_hnext != NULL)
                  is->is_hnext->is_phnext = is->is_phnext;
            if (ips_table[is->is_hv] == NULL)
                  ips_stats.iss_inuse--;
            ips_stats.iss_bucketlen[is->is_hv]--;

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

      /*
       * Because 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(ips_stats.iss_wild);
            }
            is->is_flags &= ~(SI_WILDP|SI_WILDA);
      }

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

      if (is->is_me != NULL) {
            *is->is_me = NULL;
            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.  How can this
       * be?  fr_state_flush() calls fr_delete() directly because it wants
       * to empty the table out and if something has a hold on a state
       * entry (such as ipfstat), it'll do the deref path that'll bring
       * us back here to do the real delete & free.
       */
      MUTEX_ENTER(&is->is_lock);
      if (is->is_ref > 1) {
            is->is_ref--;
            MUTEX_EXIT(&is->is_lock);
            return is->is_ref;
      }
      MUTEX_EXIT(&is->is_lock);

      is->is_ref = 0;

      if (is->is_tqehead[0] != NULL) {
            if (fr_deletetimeoutqueue(is->is_tqehead[0]) == 0)
                  fr_freetimeoutqueue(is->is_tqehead[0]);
      }
      if (is->is_tqehead[1] != NULL) {
            if (fr_deletetimeoutqueue(is->is_tqehead[1]) == 0)
                  fr_freetimeoutqueue(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 the linked list of known states
       */
      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_pnext = NULL;
            is->is_next = NULL;
      }

      if (ipstate_logging != 0 && why != 0)
            ipstate_log(is, why);

      if (is->is_p == IPPROTO_TCP)
            ips_stats.iss_fin++;
      else
            ips_stats.iss_expire++;

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

      MUTEX_DESTROY(&is->is_lock);
      KFREE(is);
      ips_num--;

      return 0;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_timeoutstate                                             */
/* Returns:     Nil                                                         */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* 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()
{
      ipftq_t *ifq, *ifqnext;
      ipftqent_t *tqe, *tqn;
      ipstate_t *is;
      SPL_INT(s);

      SPL_NET(s);
      WRITE_ENTER(&ipf_state);
      for (ifq = ips_tqtqb; ifq != NULL; ifq = ifq->ifq_next)
            for (tqn = ifq->ifq_head; ((tqe = tqn) != NULL); ) {
                  if (tqe->tqe_die > fr_ticks)
                        break;
                  tqn = tqe->tqe_next;
                  is = tqe->tqe_parent;
                  fr_delstate(is, ISL_EXPIRE);
            }

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

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

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

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

      if (fr_state_doflush) {
            (void) fr_state_flush(2, 0);
            fr_state_doflush = 0;
      }

      RWLOCK_EXIT(&ipf_state);
      SPL_X(s);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_state_flush                                              */
/* Returns:     int - 0 == success, -1 == failure                           */
/* Parameters:  Nil                                                         */
/* Write Locks: ipf_state                                                   */
/*                                                                          */
/* Flush state tables.  Three actions currently defined:                    */
/* which == 0 : flush all state table entries                               */
/* which == 1 : flush TCP connections which have started to close but are   */
/*          stuck for some reason.                                        */
/* which == 2 : flush TCP connections which have been idle for a long time, */
/*          starting at > 4 days idle and working back in successive half-*/
/*          days to at most 12 hours old.  If this fails to free enough   */
/*            slots then work backwards in half hour slots to 30 minutes.   */
/*            If that too fails, then work backwards in 30 second intervals */
/*            for the last 30 minutes to at worst 30 seconds idle.          */
/* ------------------------------------------------------------------------ */
static int fr_state_flush(which, proto)
int which, proto;
{
      ipftq_t *ifq, *ifqnext;
      ipftqent_t *tqe, *tqn;
      ipstate_t *is, **isp;
      int removed;
      SPL_INT(s);

      removed = 0;

      SPL_NET(s);

      switch (which)
      {
      case 0 :
            /*
             * Style 0 flush removes everything...
             */
            for (isp = &ips_list; ((is = *isp) != NULL); ) {
                  if ((proto != 0) && (is->is_v != proto)) {
                        isp = &is->is_next;
                        continue;
                  }
                  if (fr_delstate(is, ISL_FLUSH) == 0)
                        removed++;
                  else
                        isp = &is->is_next;
            }
            break;

      case 1 :
            /*
             * Since we're only interested in things that are closing,
             * we can start with the appropriate timeout queue.
             */
            for (ifq = ips_tqtqb + IPF_TCPS_CLOSE_WAIT; ifq != NULL;
                 ifq = ifq->ifq_next) {

                  for (tqn = ifq->ifq_head; ((tqe = tqn) != NULL); ) {
                        tqn = tqe->tqe_next;
                        is = tqe->tqe_parent;
                        if (is->is_p != IPPROTO_TCP)
                              break;
                        if (fr_delstate(is, ISL_EXPIRE) == 0)
                              removed++;
                  }
            }

            /*
             * Also need to look through the user defined queues.
             */
            for (ifq = ips_utqe; ifq != NULL; ifq = ifqnext) {
                  ifqnext = ifq->ifq_next;
                  for (tqn = ifq->ifq_head; ((tqe = tqn) != NULL); ) {
                        tqn = tqe->tqe_next;
                        is = tqe->tqe_parent;
                        if (is->is_p != IPPROTO_TCP)
                              continue;

                        if ((is->is_state[0] > IPF_TCPS_ESTABLISHED) &&
                            (is->is_state[1] > IPF_TCPS_ESTABLISHED)) {
                              if (fr_delstate(is, ISL_EXPIRE) == 0)
                                    removed++;
                        }
                  }
            }
            break;

      case 2 :
            break;

            /*  
             * Args 5-11 correspond to flushing those particular states
             * for TCP connections.
             */
      case IPF_TCPS_CLOSE_WAIT :
      case IPF_TCPS_FIN_WAIT_1 :
      case IPF_TCPS_CLOSING :
      case IPF_TCPS_LAST_ACK :
      case IPF_TCPS_FIN_WAIT_2 :
      case IPF_TCPS_TIME_WAIT :
      case IPF_TCPS_CLOSED :
            tqn = ips_tqtqb[which].ifq_head;
            while (tqn != NULL) {
                  tqe = tqn;
                  tqn = tqe->tqe_next;
                  is = tqe->tqe_parent;
                  if (fr_delstate(is, ISL_FLUSH) == 0)
                        removed++;
            }
            break;

      default :
            if (which < 30)
                  break;

            /* 
             * Take a large arbitrary number to mean the number of seconds
             * for which which consider to be the maximum value we'll allow
             * the expiration to be.
             */
            which = IPF_TTLVAL(which);
            for (isp = &ips_list; ((is = *isp) != NULL); ) {
                  if ((proto == 0) || (is->is_v == proto)) {
                        if (fr_ticks - is->is_touched > which) {
                              if (fr_delstate(is, ISL_FLUSH) == 0) {
                                    removed++;
                                    continue;
                              }
                        }
                  }
                  isp = &is->is_next;
            }
            break;
      }

      if (which != 2) {
            SPL_X(s);
            return removed;
      }

      /*
       * Asked to remove inactive entries because the table is full.
       */
      if (fr_ticks - ips_last_force_flush > IPF_TTLVAL(5)) {
            ips_last_force_flush = fr_ticks;
                removed = ipf_queueflush(fr_state_flush_entry, ips_tqtqb,
                               ips_utqe);
      }

      SPL_X(s);
      return removed;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_state_flush_entry                                        */
/* Returns:     int - 0 = entry deleted, else not deleted                   */
/* Parameters:  entry(I)  - pointer to state structure to delete            */
/* Write Locks: ipf_state                                                   */
/*                                                                          */
/* This function is a stepping stone between ipf_queueflush() and           */
/* fr_delstate().  It is used so we can provide a uniform interface via the */
/* ipf_queueflush() function.                                               */
/* ------------------------------------------------------------------------ */
static int fr_state_flush_entry(entry)
void *entry;
{
      return fr_delstate(entry, ISL_FLUSH);
}     


/* ------------------------------------------------------------------------ */
/* 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                               */
/*                                                                          */
/* A typical procession for a connection is as follows:                     */
/*                                                                          */
/* +--------------+-------------------+                                     */
/* | Side '0'     | Side '1'          |                                     */
/* +--------------+-------------------+                                     */
/* | 0 -> 1 (SYN) |                   |                                     */
/* |              | 0 -> 2 (SYN-ACK)  |                                     */
/* | 1 -> 3 (ACK) |                   |                                     */
/* |              | 2 -> 4 (ACK-PUSH) |                                     */
/* | 3 -> 4 (ACK) |                   |                                     */
/* |   ...        |   ...             |                                     */
/* |              | 4 -> 6 (FIN-ACK)  |                                     */
/* | 4 -> 5 (ACK) |                   |                                     */
/* |              | 6 -> 6 (ACK-PUSH) |                                     */
/* | 5 -> 5 (ACK) |                   |                                     */
/* | 5 -> 8 (FIN) |                   |                                     */
/* |              | 6 -> 10 (ACK)     |                                     */
/* +--------------+-------------------+                                     */
/*                                                                          */
/* 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;

      tcp = fin->fin_dp;

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

      if (tcpflags & TH_RST) {
            if (!(tcpflags & TH_PUSH) && !dlen)
                  nstate = IPF_TCPS_CLOSED;
            else
                  nstate = IPF_TCPS_CLOSE_WAIT;
            rval = 1;
      } else {
            ostate = tqe->tqe_state[1 - dir];
            nstate = tqe->tqe_state[dir];

            switch (nstate)
            {
            case IPF_TCPS_LISTEN: /* 0 */
                  if ((tcpflags & TH_OPENING) == TH_OPENING) {
                        /*
                         * 'dir' received an S and sends SA in
                         * response, LISTEN -> SYN_RECEIVED
                         */
                        nstate = IPF_TCPS_SYN_RECEIVED;
                        rval = 1;
                  } else if ((tcpflags & TH_OPENING) == TH_SYN) {
                        /* 'dir' sent S, LISTEN -> 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 TIME_WAIT
                         */
                        /*
                         * XXX: how do we know we really are ACKing
                         * the FIN packet here? does the window code
                         * guarantee that?
                         */
                        nstate = IPF_TCPS_TIME_WAIT;
                  } 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 = 2;
                  break;

            case IPF_TCPS_LAST_ACK: /* 8 */
                  if (tcpflags & TH_ACK) {
                        if ((tcpflags & TH_PUSH) || dlen)
                              /*
                               * there is still data to be delivered,
                               * reset timeout
                               */
                              rval = 1;
                        else
                              rval = 2;
                  }
                  /*
                   * we cannot detect when we go out of LAST_ACK state to
                   * CLOSED because that is based on the reception of ACK
                   * packets; ipfilter can only detect that a packet
                   * has been sent by a host
                   */
                  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;
                  break;

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

            default :
#if defined(_KERNEL)
# if SOLARIS
                  cmn_err(CE_NOTE,
                        "tcp %lx flags %x si %lx nstate %d ostate %d\n",
                        (u_long)tcp, tcpflags, (u_long)tqe,
                        nstate, ostate);
# else
                  printf("tcp %lx flags %x si %lx nstate %d ostate %d\n",
                        (u_long)tcp, tcpflags, (u_long)tqe,
                        nstate, ostate);
# endif
#else
                  abort();
#endif
                  break;
            }
      }

      /*
       * If rval == 2 then do not update the queue position, but treat the
       * packet as being ok.
       */
      if (rval == 2)
            rval = 1;
      else if (rval == 1) {
            tqe->tqe_state[dir] = nstate;
            if ((tqe->tqe_flags & TQE_RULEBASED) == 0)
                  fr_movequeue(tqe, tqe->tqe_ifq, tqtab + nstate);
      }

      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)
struct ipstate *is;
u_int type;
{
#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)) {
            ATOMIC_INCL(ips_stats.iss_logged);
      } else {
            ATOMIC_INCL(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 type, 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;

      /*
       * 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;
      type = ic6->icmp6_type;

      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;
      (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);

            READ_ENTER(&ipf_state);
            for (isp = &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 )) {
                              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(&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);

      READ_ENTER(&ipf_state);
      for (isp = &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) {
                  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(&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)
ipftq_t *tqp;
{
      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 = fr_tcpclosed;
      tqp[IPF_TCPS_LISTEN].ifq_ttl = fr_tcptimeout;
      tqp[IPF_TCPS_SYN_SENT].ifq_ttl = fr_tcptimeout;
      tqp[IPF_TCPS_SYN_RECEIVED].ifq_ttl = fr_tcptimeout;
      tqp[IPF_TCPS_ESTABLISHED].ifq_ttl = fr_tcpidletimeout;
      tqp[IPF_TCPS_CLOSE_WAIT].ifq_ttl = fr_tcphalfclosed;
      tqp[IPF_TCPS_FIN_WAIT_1].ifq_ttl = fr_tcphalfclosed;
      tqp[IPF_TCPS_CLOSING].ifq_ttl = fr_tcptimeout;
      tqp[IPF_TCPS_LAST_ACK].ifq_ttl = fr_tcplastack;
      tqp[IPF_TCPS_FIN_WAIT_2].ifq_ttl = fr_tcpclosewait;
      tqp[IPF_TCPS_TIME_WAIT].ifq_ttl = fr_tcptimewait;
      tqp[IPF_TCPS_HALF_ESTAB].ifq_ttl = 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            */
/*                                                                          */
/* Decrement the reference counter for this state table entry and free it   */
/* if there are no more things using it.                                    */
/*                                                                          */
/* This function is only called when cleaning up after increasing is_ref by */
/* one earlier in the 'code path' so if is_ref is 1 when entering, we do    */
/* have an orphan, otherwise not.  However there is a possible race between */
/* the entry being deleted via flushing with an ioctl call (that calls the  */
/* delete function directly) and the tail end of packet processing so we    */
/* need to grab is_lock before doing the check to synchronise the two code  */
/* paths.                                                                   */
/*                                                                          */
/* When operating in userland (ipftest), we have no timers to clear a state */
/* entry.  Therefore, we make a few simple tests before deleting an entry   */
/* outright.  We compare states on each side looking for a combination of   */
/* TIME_WAIT (should really be FIN_WAIT_2?) and LAST_ACK.  Then we factor   */
/* in packet direction with the interface list to make sure we don't        */
/* prematurely delete an entry on a final inbound packet that's we're also  */
/* supposed to route elsewhere.                                             */
/*                                                                          */
/* 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                               */
/* ------------------------------------------------------------------------ */
void fr_statederef(isp)
ipstate_t **isp;
{
      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)) {
                  fr_delstate(is, ISL_ORPHAN);
            }
#endif
            return;
      }
      MUTEX_EXIT(&is->is_lock);

      WRITE_ENTER(&ipf_state);
      fr_delstate(is, ISL_EXPIRE);
      RWLOCK_EXIT(&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)
ipstate_t *is;
int rev;
{
      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 = &ips_icmpacktq;
                  else
                        nifq = &ips_icmptq;
                  break;
#endif
            case IPPROTO_ICMP :
                  if (rev == 1)
                        nifq = &ips_icmpacktq;
                  else
                        nifq = &ips_icmptq;
                  break;
            case IPPROTO_TCP :
                  nifq = ips_tqtqb + is->is_state[rev];
                  break;

            case IPPROTO_UDP :
                  if (rev == 1)
                        nifq = &ips_udpacktq;
                  else
                        nifq = &ips_udptq;
                  break;

            default :
                  nifq = &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);
      else
            fr_queueappend(&is->is_sti, nifq, is);
      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)
ipftoken_t *token;
ipfgeniter_t *itp;
{
      ipstate_t *is, *next, zero;
      int error, count;
      char *dst;

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

      if (itp->igi_nitems < 1)
            return ENOSPC;

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

      is = token->ipt_data;
      if (is == (void *)-1) {
            ipf_freetoken(token);
            return ESRCH;
      }

      error = 0;
      dst = itp->igi_data;

      READ_ENTER(&ipf_state);
      if (is == NULL) {
            next = ips_list;
      } else {
            next = is->is_next;
      }

      count = itp->igi_nitems;
      for (;;) {
            if (next != NULL) {
                  /*
                   * If we find a state entry to use, bump its
                   * reference count so that it can be used for
                   * is_next when we come back.
                   */
                  if (count == 1) {
                        MUTEX_ENTER(&next->is_lock);
                        next->is_ref++;
                        MUTEX_EXIT(&next->is_lock);
                        token->ipt_data = next;
                  }
            } else {
                  bzero(&zero, sizeof(zero));
                  next = &zero;
                  count = 1;
                  token->ipt_data = NULL;
            }
            RWLOCK_EXIT(&ipf_state);

            /*
             * This should arguably be via fr_outobj() so that the state
             * structure can (if required) be massaged going out.
             */
            error = COPYOUT(next, dst, sizeof(*next));
            if (error != 0)
                  error = EFAULT;
            if ((count == 1) || (error != 0))
                  break;

            dst += sizeof(*next);
            count--;

            READ_ENTER(&ipf_state);
            next = next->is_next;
      }

      if (is != NULL) {
            fr_statederef(&is);
      }

      return error;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_stgettable                                               */
/* Returns:     int     - 0 = success, else error                           */
/* Parameters:  data(I) - pointer to ioctl data                             */
/*                                                                          */
/* This function handles ioctl requests for tables of state information.    */
/* At present the only table it deals with is the hash bucket statistics.   */
/* ------------------------------------------------------------------------ */
static int fr_stgettable(data)
char *data;
{
      ipftable_t table;
      int error;

      error = fr_inobj(data, &table, IPFOBJ_GTABLE);
      if (error != 0)
            return error;

      if (table.ita_type != IPFTABLE_BUCKETS)
            return EINVAL;

      error = COPYOUT(ips_stats.iss_bucketlen, table.ita_table, 
                  fr_statesize * sizeof(u_long));
      if (error != 0)
            error = EFAULT;
      return error;
}

Generated by  Doxygen 1.6.0   Back to index