/*
 * Copyright (C) 1993-2003 by Darren Reed.
 *
 * See the IPFILTER.LICENCE file for details on licencing.
 *
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#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/time.h>
#include <sys/file.h>
#ifdef __hpux
# include <sys/timeout.h>
#endif
#if !defined(_KERNEL)
# include <stdio.h>
# include <string.h>
# include <stdlib.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>
#else
# include <sys/ioctl.h>
#endif
#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__)
# if defined(_KERNEL) && !defined(__sgi) && !defined(AIX)
#  include <sys/kernel.h>
# endif
#else
# 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>
#if !defined(linux)
# include <netinet/ip_var.h>
#endif
#include <netinet/tcp.h>
#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_auth.h"
#include "netinet/ipf_stack.h"
#if (__FreeBSD_version >= 300000)
# include <sys/malloc.h>
# if defined(_KERNEL)
#  ifndef IPFILTER_LKM
#   include <sys/libkern.h>
#   include <sys/systm.h>
#  endif
extern struct callout_handle fr_slowtimer_ch;
# endif
#endif
#if defined(__NetBSD__) && (__NetBSD_Version__ >= 104230000)
# include <sys/callout.h>
extern struct callout fr_slowtimer_ch;
#endif
#if defined(__OpenBSD__)
# include <sys/timeout.h>
extern struct timeout fr_slowtimer_ch;
#endif
/* END OF INCLUDES */

#if !defined(lint)
static const char sccsid[] = "@(#)ip_frag.c     1.11 3/24/96 (C) 1993-2000 Darren Reed";
static const char rcsid[] = "@(#)$Id: ip_frag.c,v 2.77.2.5 2005/08/11 14:33:10 darrenr Exp $";
#endif

static INLINE int ipfr_index __P((fr_info_t *, ipfr_t *));
static ipfr_t *ipfr_newfrag __P((fr_info_t *, u_32_t, ipfr_t **));
static ipfr_t *fr_fraglookup __P((fr_info_t *, ipfr_t **));
static void fr_fragdelete __P((ipfr_t *, ipfr_t ***, ipf_stack_t *));

/* ------------------------------------------------------------------------ */
/* Function:    fr_fraginit                                                 */
/* Returns:     int - 0 == success, -1 == error                             */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Initialise the hash tables for the fragment cache lookups.               */
/* ------------------------------------------------------------------------ */
int fr_fraginit(ifs)
ipf_stack_t *ifs;
{
        ifs->ifs_ipfr_tail = &ifs->ifs_ipfr_list;
        ifs->ifs_ipfr_nattail = &ifs->ifs_ipfr_natlist;
        ifs->ifs_ipfr_ipidtail = &ifs->ifs_ipfr_ipidlist;
        /* the IP frag related variables are set in ipftuneable_setdefs() to
         * their default values
         */

        KMALLOCS(ifs->ifs_ipfr_heads, ipfr_t **,
            ifs->ifs_ipfr_size * sizeof(ipfr_t *));
        if (ifs->ifs_ipfr_heads == NULL)
                return -1;
        bzero((char *)ifs->ifs_ipfr_heads,
            ifs->ifs_ipfr_size * sizeof(ipfr_t *));

        KMALLOCS(ifs->ifs_ipfr_nattab, ipfr_t **,
            ifs->ifs_ipfr_size * sizeof(ipfr_t *));
        if (ifs->ifs_ipfr_nattab == NULL)
                return -1;
        bzero((char *)ifs->ifs_ipfr_nattab,
            ifs->ifs_ipfr_size * sizeof(ipfr_t *));

        KMALLOCS(ifs->ifs_ipfr_ipidtab, ipfr_t **,
            ifs->ifs_ipfr_size * sizeof(ipfr_t *));
        if (ifs->ifs_ipfr_ipidtab == NULL)
                return -1;
        bzero((char *)ifs->ifs_ipfr_ipidtab,
            ifs->ifs_ipfr_size * sizeof(ipfr_t *));

        RWLOCK_INIT(&ifs->ifs_ipf_frag, "ipf fragment rwlock");

        /* Initialise frblock with "block in all" */
        bzero((char *)&ifs->ifs_frblock, sizeof(ifs->ifs_frblock));
        ifs->ifs_frblock.fr_flags = FR_BLOCK|FR_INQUE;  /* block in */
        ifs->ifs_frblock.fr_ref = 1;

        ifs->ifs_fr_frag_init = 1;

        return 0;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fragunload                                               */
/* Returns:     Nil                                                         */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Free all memory allocated whilst running and from initialisation.        */
/* ------------------------------------------------------------------------ */
void fr_fragunload(ifs)
ipf_stack_t *ifs;
{
        if (ifs->ifs_fr_frag_init == 1) {
                fr_fragclear(ifs);

                RW_DESTROY(&ifs->ifs_ipf_frag);
                ifs->ifs_fr_frag_init = 0;
        }

        if (ifs->ifs_ipfr_heads != NULL) {
                KFREES(ifs->ifs_ipfr_heads,
                    ifs->ifs_ipfr_size * sizeof(ipfr_t *));
        }
        ifs->ifs_ipfr_heads = NULL;

        if (ifs->ifs_ipfr_nattab != NULL) {
                KFREES(ifs->ifs_ipfr_nattab,
                    ifs->ifs_ipfr_size * sizeof(ipfr_t *));
        }
        ifs->ifs_ipfr_nattab = NULL;

        if (ifs->ifs_ipfr_ipidtab != NULL) {
                KFREES(ifs->ifs_ipfr_ipidtab,
                    ifs->ifs_ipfr_size * sizeof(ipfr_t *));
        }
        ifs->ifs_ipfr_ipidtab = NULL;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fragstats                                                */
/* Returns:     ipfrstat_t* - pointer to struct with current frag stats     */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Updates ipfr_stats with current information and returns a pointer to it  */
/* ------------------------------------------------------------------------ */
ipfrstat_t *fr_fragstats(ifs)
ipf_stack_t *ifs;
{
        ifs->ifs_ipfr_stats.ifs_table = ifs->ifs_ipfr_heads;
        ifs->ifs_ipfr_stats.ifs_nattab = ifs->ifs_ipfr_nattab;
        ifs->ifs_ipfr_stats.ifs_inuse = ifs->ifs_ipfr_inuse;
        return &ifs->ifs_ipfr_stats;
}


/* ------------------------------------------------------------------------ */
/* Function:    ipfr_index                                                  */
/* Returns:     int     - index in fragment table for given packet          */
/* Parameters:  fin(I)  - pointer to packet information                     */
/*              frag(O) - pointer to ipfr_t structure to fill               */
/*                                                                          */
/* Compute the index in the fragment table while filling the per packet     */
/* part of the fragment state.                                              */
/* ------------------------------------------------------------------------ */
static INLINE int ipfr_index(fin, frag)
fr_info_t *fin;
ipfr_t *frag;
{
        u_int idx;

        /*
         * For fragments, we record protocol, packet id, TOS and both IP#'s
         * (these should all be the same for all fragments of a packet).
         *
         * build up a hash value to index the table with.
         */

#ifdef  USE_INET6
        if (fin->fin_v == 6) {
                ip6_t *ip6 = (ip6_t *)fin->fin_ip;

                frag->ipfr_p = fin->fin_fi.fi_p;
                frag->ipfr_id = fin->fin_id;
                frag->ipfr_tos = ip6->ip6_flow & IPV6_FLOWINFO_MASK;
                frag->ipfr_src.in6 = ip6->ip6_src;
                frag->ipfr_dst.in6 = ip6->ip6_dst;
        } else
#endif
        {
                ip_t *ip = fin->fin_ip;

                frag->ipfr_p = ip->ip_p;
                frag->ipfr_id = ip->ip_id;
                frag->ipfr_tos = ip->ip_tos;
                frag->ipfr_src.in4.s_addr = ip->ip_src.s_addr;
                frag->ipfr_src.i6[1] = 0;
                frag->ipfr_src.i6[2] = 0;
                frag->ipfr_src.i6[3] = 0;
                frag->ipfr_dst.in4.s_addr = ip->ip_dst.s_addr;
                frag->ipfr_dst.i6[1] = 0;
                frag->ipfr_dst.i6[2] = 0;
                frag->ipfr_dst.i6[3] = 0;
        }
        frag->ipfr_ifp = fin->fin_ifp;
        frag->ipfr_optmsk = fin->fin_fi.fi_optmsk & IPF_OPTCOPY;
        frag->ipfr_secmsk = fin->fin_fi.fi_secmsk;
        frag->ipfr_auth = fin->fin_fi.fi_auth;

        idx = frag->ipfr_p;
        idx += frag->ipfr_id;
        idx += frag->ipfr_src.i6[0];
        idx += frag->ipfr_src.i6[1];
        idx += frag->ipfr_src.i6[2];
        idx += frag->ipfr_src.i6[3];
        idx += frag->ipfr_dst.i6[0];
        idx += frag->ipfr_dst.i6[1];
        idx += frag->ipfr_dst.i6[2];
        idx += frag->ipfr_dst.i6[3];
        idx *= 127;
        idx %= IPFT_SIZE;

        return idx;
}


/* ------------------------------------------------------------------------ */
/* Function:    ipfr_newfrag                                                */
/* Returns:     ipfr_t * - pointer to fragment cache state info or NULL     */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              table(I) - pointer to frag table to add to                  */
/*                                                                          */
/* Add a new entry to the fragment cache, registering it as having come     */
/* through this box, with the result of the filter operation.               */
/* ------------------------------------------------------------------------ */
static ipfr_t *ipfr_newfrag(fin, pass, table)
fr_info_t *fin;
u_32_t pass;
ipfr_t *table[];
{
        ipfr_t *fra, frag;
        u_int idx, off;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_ipfr_inuse >= ifs->ifs_ipfr_size)
                return NULL;

        if ((fin->fin_flx & (FI_FRAG|FI_BAD)) != FI_FRAG)
                return NULL;

        if (pass & FR_FRSTRICT)
                if (fin->fin_off != 0)
                        return NULL;

        idx = ipfr_index(fin, &frag);

        /*
         * first, make sure it isn't already there...
         */
        for (fra = table[idx]; (fra != NULL); fra = fra->ipfr_hnext)
                if (!bcmp((char *)&frag.ipfr_ifp, (char *)&fra->ipfr_ifp,
                          IPFR_CMPSZ)) {
                        ifs->ifs_ipfr_stats.ifs_exists++;
                        return NULL;
                }

        /*
         * allocate some memory, if possible, if not, just record that we
         * failed to do so.
         */
        KMALLOC(fra, ipfr_t *);
        if (fra == NULL) {
                ifs->ifs_ipfr_stats.ifs_nomem++;
                return NULL;
        }

        fra->ipfr_rule = fin->fin_fr;
        if (fra->ipfr_rule != NULL) {

                frentry_t *fr;

                fr = fin->fin_fr;
                MUTEX_ENTER(&fr->fr_lock);
                fr->fr_ref++;
                MUTEX_EXIT(&fr->fr_lock);
        }

        /*
         * Insert the fragment into the fragment table, copy the struct used
         * in the search using bcopy rather than reassign each field.
         * Set the ttl to the default.
         */
        if ((fra->ipfr_hnext = table[idx]) != NULL)
                table[idx]->ipfr_hprev = &fra->ipfr_hnext;
        fra->ipfr_hprev = table + idx;
        fra->ipfr_data = NULL;
        table[idx] = fra;
        bcopy((char *)&frag.ipfr_ifp, (char *)&fra->ipfr_ifp, IPFR_CMPSZ);
        fra->ipfr_ttl = ifs->ifs_fr_ticks + ifs->ifs_fr_ipfrttl;

        /*
         * Compute the offset of the expected start of the next packet.
         */
        off = fin->fin_off >> 3;
        if (off == 0) {
                fra->ipfr_seen0 = 1;
        } else {
                fra->ipfr_seen0 = 0;
        }
        fra->ipfr_off = off + fin->fin_dlen;
        fra->ipfr_pass = pass;
        fra->ipfr_ref = 1;
        ifs->ifs_ipfr_stats.ifs_new++;
        ifs->ifs_ipfr_inuse++;
        return fra;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_newfrag                                                  */
/* Returns:     int - 0 == success, -1 == error                             */
/* Parameters:  fin(I)  - pointer to packet information                     */
/*                                                                          */
/* Add a new entry to the fragment cache table based on the current packet  */
/* ------------------------------------------------------------------------ */
int fr_newfrag(fin, pass)
u_32_t pass;
fr_info_t *fin;
{
        ipfr_t  *fra;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_frag_lock != 0)
                return -1;

        WRITE_ENTER(&ifs->ifs_ipf_frag);
        fra = ipfr_newfrag(fin, pass, ifs->ifs_ipfr_heads);
        if (fra != NULL) {
                *ifs->ifs_ipfr_tail = fra;
                fra->ipfr_prev = ifs->ifs_ipfr_tail;
                ifs->ifs_ipfr_tail = &fra->ipfr_next;
                if (ifs->ifs_ipfr_list == NULL)
                        ifs->ifs_ipfr_list = fra;
                fra->ipfr_next = NULL;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_frag);
        return fra ? 0 : -1;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_nat_newfrag                                              */
/* Returns:     int - 0 == success, -1 == error                             */
/* Parameters:  fin(I)  - pointer to packet information                     */
/*              nat(I)  - pointer to NAT structure                          */
/*                                                                          */
/* Create a new NAT fragment cache entry based on the current packet and    */
/* the NAT structure for this "session".                                    */
/* ------------------------------------------------------------------------ */
int fr_nat_newfrag(fin, pass, nat)
fr_info_t *fin;
u_32_t pass;
nat_t *nat;
{
        ipfr_t  *fra;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_frag_lock != 0)
                return 0;

        WRITE_ENTER(&ifs->ifs_ipf_natfrag);
        fra = ipfr_newfrag(fin, pass, ifs->ifs_ipfr_nattab);
        if (fra != NULL) {
                fra->ipfr_data = nat;
                nat->nat_data = fra;
                *ifs->ifs_ipfr_nattail = fra;
                fra->ipfr_prev = ifs->ifs_ipfr_nattail;
                ifs->ifs_ipfr_nattail = &fra->ipfr_next;
                fra->ipfr_next = NULL;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_natfrag);
        return fra ? 0 : -1;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_ipid_newfrag                                             */
/* Returns:     int - 0 == success, -1 == error                             */
/* Parameters:  fin(I)  - pointer to packet information                     */
/*              ipid(I) - new IP ID for this fragmented packet              */
/*                                                                          */
/* Create a new fragment cache entry for this packet and store, as a data   */
/* pointer, the new IP ID value.                                            */
/* ------------------------------------------------------------------------ */
int fr_ipid_newfrag(fin, ipid)
fr_info_t *fin;
u_32_t ipid;
{
        ipfr_t  *fra;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_frag_lock)
                return 0;

        WRITE_ENTER(&ifs->ifs_ipf_ipidfrag);
        fra = ipfr_newfrag(fin, 0, ifs->ifs_ipfr_ipidtab);
        if (fra != NULL) {
                fra->ipfr_data = (void *)(uintptr_t)ipid;
                *ifs->ifs_ipfr_ipidtail = fra;
                fra->ipfr_prev = ifs->ifs_ipfr_ipidtail;
                ifs->ifs_ipfr_ipidtail = &fra->ipfr_next;
                fra->ipfr_next = NULL;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_ipidfrag);
        return fra ? 0 : -1;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fraglookup                                               */
/* Returns:     ipfr_t * - pointer to ipfr_t structure if there's a         */
/*                         matching entry in the frag table, else NULL      */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              table(I) - pointer to fragment cache table to search        */
/*                                                                          */
/* Check the fragment cache to see if there is already a record of this     */
/* packet with its filter result known.                                     */
/* ------------------------------------------------------------------------ */
static ipfr_t *fr_fraglookup(fin, table)
fr_info_t *fin;
ipfr_t *table[];
{
        ipfr_t *f, frag;
        u_int idx;
        ipf_stack_t *ifs = fin->fin_ifs;

        if ((fin->fin_flx & (FI_FRAG|FI_BAD)) != FI_FRAG)
                return NULL;

        /*
         * For fragments, we record protocol, packet id, TOS and both IP#'s
         * (these should all be the same for all fragments of a packet).
         *
         * build up a hash value to index the table with.
         */
        idx = ipfr_index(fin, &frag);

        /*
         * check the table, careful to only compare the right amount of data
         */
        for (f = table[idx]; f; f = f->ipfr_hnext) {
                if (!bcmp((char *)&frag.ipfr_ifp, (char *)&f->ipfr_ifp,
                          IPFR_CMPSZ)) {
                        u_short off;

                        /*
                         * We don't want to let short packets match because
                         * they could be compromising the security of other
                         * rules that want to match on layer 4 fields (and
                         * can't because they have been fragmented off.)
                         * Why do this check here?  The counter acts as an
                         * indicator of this kind of attack, whereas if it was
                         * elsewhere, it wouldn't know if other matching
                         * packets had been seen.
                         */
                        if (fin->fin_flx & FI_SHORT) {
                                ATOMIC_INCL(ifs->ifs_ipfr_stats.ifs_short);
                                continue;
                        }

                        /*
                         * XXX - We really need to be guarding against the
                         * retransmission of (src,dst,id,offset-range) here
                         * because a fragmented packet is never resent with
                         * the same IP ID# (or shouldn't).
                         */
                        off = fin->fin_off >> 3;
                        if (f->ipfr_seen0) {
                                if (off == 0) {
                                        ATOMIC_INCL(ifs->ifs_ipfr_stats.ifs_retrans0);
                                        continue;
                                }
                        } else if (off == 0) {
                                f->ipfr_seen0 = 1;
                        }

                        /*
                         * If we've follwed the fragments, and this is the
                         * last (in order), shrink expiration time.
                         */
                        if (off == f->ipfr_off) {
                                if (!(fin->fin_flx & FI_MOREFRAG))
                                        f->ipfr_ttl = ifs->ifs_fr_ticks + 1;
                                f->ipfr_off = fin->fin_dlen + off;
                        } else if (f->ipfr_pass & FR_FRSTRICT) {
                                continue;
                        }
                        ATOMIC_INCL(ifs->ifs_ipfr_stats.ifs_hits);
                        return f;
                }
        }

        return NULL;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_nat_knownfrag                                            */
/* Returns:     nat_t* - pointer to 'parent' NAT structure if frag table    */
/*                       match found, else NULL                             */
/* Parameters:  fin(I)  - pointer to packet information                     */
/*                                                                          */
/* Functional interface for NAT lookups of the NAT fragment cache           */
/* ------------------------------------------------------------------------ */
nat_t *fr_nat_knownfrag(fin)
fr_info_t *fin;
{
        nat_t   *nat;
        ipfr_t  *ipf;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_frag_lock || !ifs->ifs_ipfr_natlist)
                return NULL;
        READ_ENTER(&ifs->ifs_ipf_natfrag);
        ipf = fr_fraglookup(fin, ifs->ifs_ipfr_nattab);
        if (ipf != NULL) {
                nat = ipf->ipfr_data;
                /*
                 * This is the last fragment for this packet.
                 */
                if ((ipf->ipfr_ttl == ifs->ifs_fr_ticks + 1) && (nat != NULL)) {
                        nat->nat_data = NULL;
                        ipf->ipfr_data = NULL;
                }
        } else
                nat = NULL;
        RWLOCK_EXIT(&ifs->ifs_ipf_natfrag);
        return nat;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_ipid_knownfrag                                           */
/* Returns:     u_32_t - IPv4 ID for this packet if match found, else       */
/*                       return 0xfffffff to indicate no match.             */
/* Parameters:  fin(I) - pointer to packet information                      */
/*                                                                          */
/* Functional interface for IP ID lookups of the IP ID fragment cache       */
/* ------------------------------------------------------------------------ */
u_32_t fr_ipid_knownfrag(fin)
fr_info_t *fin;
{
        ipfr_t  *ipf;
        u_32_t  id;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_frag_lock || !ifs->ifs_ipfr_ipidlist)
                return 0xffffffff;

        READ_ENTER(&ifs->ifs_ipf_ipidfrag);
        ipf = fr_fraglookup(fin, ifs->ifs_ipfr_ipidtab);
        if (ipf != NULL)
                id = (u_32_t)(uintptr_t)ipf->ipfr_data;
        else
                id = 0xffffffff;
        RWLOCK_EXIT(&ifs->ifs_ipf_ipidfrag);
        return id;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_knownfrag                                                */
/* Returns:     frentry_t* - pointer to filter rule if a match is found in  */
/*                           the frag cache table, else NULL.               */
/* Parameters:  fin(I)   - pointer to packet information                    */
/*              passp(O) - pointer to where to store rule flags resturned   */
/*                                                                          */
/* Functional interface for normal lookups of the fragment cache.  If a     */
/* match is found, return the rule pointer and flags from the rule, except  */
/* that if FR_LOGFIRST is set, reset FR_LOG.                                */
/* ------------------------------------------------------------------------ */
frentry_t *fr_knownfrag(fin, passp)
fr_info_t *fin;
u_32_t *passp;
{
        frentry_t *fr = NULL;
        ipfr_t  *fra;
        u_32_t pass, oflx;
        ipf_stack_t *ifs = fin->fin_ifs;

        if (ifs->ifs_fr_frag_lock || (ifs->ifs_ipfr_list == NULL))
                return NULL;

        READ_ENTER(&ifs->ifs_ipf_frag);
        oflx = fin->fin_flx;
        fra = fr_fraglookup(fin, ifs->ifs_ipfr_heads);
        if (fra != NULL) {
                fr = fra->ipfr_rule;
                fin->fin_fr = fr;
                if (fr != NULL) {
                        pass = fr->fr_flags;
                        if ((pass & FR_LOGFIRST) != 0)
                                pass &= ~(FR_LOGFIRST|FR_LOG);
                        *passp = pass;
                }
        }
        if (!(oflx & FI_BAD) && (fin->fin_flx & FI_BAD)) {
                *passp &= ~FR_CMDMASK;
                *passp |= FR_BLOCK;
                fr = &ifs->ifs_frblock;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_frag);
        return fr;
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_forget                                                   */
/* Returns:     Nil                                                         */
/* Parameters:  ptr(I) - pointer to data structure                          */
/*                                                                          */
/* Search through all of the fragment cache entries and wherever a pointer  */
/* is found to match ptr, reset it to NULL.                                 */
/* ------------------------------------------------------------------------ */
void fr_forget(ptr, ifs)
void *ptr;
ipf_stack_t *ifs;
{
        ipfr_t  *fr;

        WRITE_ENTER(&ifs->ifs_ipf_frag);
        for (fr = ifs->ifs_ipfr_list; fr; fr = fr->ipfr_next)
                if (fr->ipfr_data == ptr)
                        fr->ipfr_data = NULL;
        RWLOCK_EXIT(&ifs->ifs_ipf_frag);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_forgetnat                                                */
/* Returns:     Nil                                                         */
/* Parameters:  ptr(I) - pointer to data structure                          */
/*                                                                          */
/* Search through all of the fragment cache entries for NAT and wherever a  */
/* pointer  is found to match ptr, reset it to NULL.                        */
/* ------------------------------------------------------------------------ */
void fr_forgetnat(ptr, ifs)
void *ptr;
ipf_stack_t *ifs;
{
        ipfr_t  *fr;

        WRITE_ENTER(&ifs->ifs_ipf_natfrag);
        for (fr = ifs->ifs_ipfr_natlist; fr; fr = fr->ipfr_next)
                if (fr->ipfr_data == ptr)
                        fr->ipfr_data = NULL;
        RWLOCK_EXIT(&ifs->ifs_ipf_natfrag);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fragdelete                                               */
/* Returns:     Nil                                                         */
/* Parameters:  fra(I)   - pointer to fragment structure to delete          */
/*              tail(IO) - pointer to the pointer to the tail of the frag   */
/*                         list                                             */
/*                                                                          */
/* Remove a fragment cache table entry from the table & list.  Also free    */
/* the filter rule it is associated with it if it is no longer used as a    */
/* result of decreasing the reference count.                                */
/* ------------------------------------------------------------------------ */
static void fr_fragdelete(fra, tail, ifs)
ipfr_t *fra, ***tail;
ipf_stack_t *ifs;
{
        frentry_t *fr;

        fr = fra->ipfr_rule;
        if (fr != NULL)
            (void)fr_derefrule(&fr, ifs);

        if (fra->ipfr_next)
                fra->ipfr_next->ipfr_prev = fra->ipfr_prev;
        *fra->ipfr_prev = fra->ipfr_next;
        if (*tail == &fra->ipfr_next)
                *tail = fra->ipfr_prev;

        if (fra->ipfr_hnext)
                fra->ipfr_hnext->ipfr_hprev = fra->ipfr_hprev;
        *fra->ipfr_hprev = fra->ipfr_hnext;

        if (fra->ipfr_ref <= 0)
                KFREE(fra);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fragclear                                                */
/* Returns:     Nil                                                         */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Free memory in use by fragment state information kept.  Do the normal    */
/* fragment state stuff first and then the NAT-fragment table.              */
/* ------------------------------------------------------------------------ */
void fr_fragclear(ifs)
ipf_stack_t *ifs;
{
        ipfr_t  *fra;
        nat_t   *nat;

        WRITE_ENTER(&ifs->ifs_ipf_frag);
        while ((fra = ifs->ifs_ipfr_list) != NULL) {
                fra->ipfr_ref--;
                fr_fragdelete(fra, &ifs->ifs_ipfr_tail, ifs);
        }
        ifs->ifs_ipfr_tail = &ifs->ifs_ipfr_list;
        RWLOCK_EXIT(&ifs->ifs_ipf_frag);

        WRITE_ENTER(&ifs->ifs_ipf_nat);
        WRITE_ENTER(&ifs->ifs_ipf_natfrag);
        while ((fra = ifs->ifs_ipfr_natlist) != NULL) {
                nat = fra->ipfr_data;
                if (nat != NULL) {
                        if (nat->nat_data == fra)
                                nat->nat_data = NULL;
                }
                fra->ipfr_ref--;
                fr_fragdelete(fra, &ifs->ifs_ipfr_nattail, ifs);
        }
        ifs->ifs_ipfr_nattail = &ifs->ifs_ipfr_natlist;
        RWLOCK_EXIT(&ifs->ifs_ipf_natfrag);
        RWLOCK_EXIT(&ifs->ifs_ipf_nat);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_fragexpire                                               */
/* Returns:     Nil                                                         */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Expire entries in the fragment cache table that have been there too long */
/* ------------------------------------------------------------------------ */
void fr_fragexpire(ifs)
ipf_stack_t *ifs;
{
        ipfr_t  **fp, *fra;
        nat_t   *nat;
        SPL_INT(s);

        if (ifs->ifs_fr_frag_lock)
                return;

        SPL_NET(s);
        WRITE_ENTER(&ifs->ifs_ipf_frag);
        /*
         * Go through the entire table, looking for entries to expire,
         * which is indicated by the ttl being less than or equal to
         * ifs_fr_ticks.
         */
        for (fp = &ifs->ifs_ipfr_list; ((fra = *fp) != NULL); ) {
                if (fra->ipfr_ttl > ifs->ifs_fr_ticks)
                        break;
                fra->ipfr_ref--;
                fr_fragdelete(fra, &ifs->ifs_ipfr_tail, ifs);
                ifs->ifs_ipfr_stats.ifs_expire++;
                ifs->ifs_ipfr_inuse--;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_frag);

        WRITE_ENTER(&ifs->ifs_ipf_ipidfrag);
        for (fp = &ifs->ifs_ipfr_ipidlist; ((fra = *fp) != NULL); ) {
                if (fra->ipfr_ttl > ifs->ifs_fr_ticks)
                        break;
                fra->ipfr_ref--;
                fr_fragdelete(fra, &ifs->ifs_ipfr_ipidtail, ifs);
                ifs->ifs_ipfr_stats.ifs_expire++;
                ifs->ifs_ipfr_inuse--;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_ipidfrag);

        /*
         * Same again for the NAT table, except that if the structure also
         * still points to a NAT structure, and the NAT structure points back
         * at the one to be free'd, NULL the reference from the NAT struct.
         * NOTE: We need to grab both mutex's early, and in this order so as
         * to prevent a deadlock if both try to expire at the same time.
         */
        WRITE_ENTER(&ifs->ifs_ipf_nat);
        WRITE_ENTER(&ifs->ifs_ipf_natfrag);
        for (fp = &ifs->ifs_ipfr_natlist; ((fra = *fp) != NULL); ) {
                if (fra->ipfr_ttl > ifs->ifs_fr_ticks)
                        break;
                nat = fra->ipfr_data;
                if (nat != NULL) {
                        if (nat->nat_data == fra)
                                nat->nat_data = NULL;
                }
                fra->ipfr_ref--;
                fr_fragdelete(fra, &ifs->ifs_ipfr_nattail, ifs);
                ifs->ifs_ipfr_stats.ifs_expire++;
                ifs->ifs_ipfr_inuse--;
        }
        RWLOCK_EXIT(&ifs->ifs_ipf_natfrag);
        RWLOCK_EXIT(&ifs->ifs_ipf_nat);
        SPL_X(s);
}


/* ------------------------------------------------------------------------ */
/* Function:    fr_slowtimer                                                */
/* Returns:     Nil                                                         */
/* Parameters:  Nil                                                         */
/*                                                                          */
/* Slowly expire held state for fragments.  Timeouts are set * in           */
/* expectation of this being called twice per second.                       */
/* ------------------------------------------------------------------------ */
#if !defined(_KERNEL) || (!defined(SOLARIS) && !defined(__hpux) && \
        !defined(__sgi) && !defined(__osf__) && !defined(linux))
# if defined(_KERNEL) && ((BSD >= 199103) || defined(__sgi))
void fr_slowtimer __P((void *arg))
# else
int fr_slowtimer(void *arg)
# endif
{
        ipf_stack_t *ifs = arg;

        READ_ENTER(&ifs->ifs_ipf_global);

        fr_fragexpire(ifs);
        fr_timeoutstate(ifs);
        fr_natexpire(ifs);
        fr_authexpire(ifs);
        ifs->ifs_fr_ticks++;
        if (ifs->ifs_fr_running <= 0)
                goto done;
# ifdef _KERNEL
#  if defined(__NetBSD__) && (__NetBSD_Version__ >= 104240000)
        callout_reset(&fr_slowtimer_ch, hz / 2, fr_slowtimer, NULL);
#  else
#   if defined(__OpenBSD__)
        timeout_add(&fr_slowtimer_ch, hz/2);
#   else
#    if (__FreeBSD_version >= 300000)
        fr_slowtimer_ch = timeout(fr_slowtimer, NULL, hz/2);
#    else
#     ifdef linux
        ;
#     else
        timeout(fr_slowtimer, NULL, hz/2);
#     endif
#    endif /* FreeBSD */
#   endif /* OpenBSD */
#  endif /* NetBSD */
# endif
done:
        RWLOCK_EXIT(&ifs->ifs_ipf_global);
# if (BSD < 199103) || !defined(_KERNEL)
        return 0;
# endif
}
#endif /* !SOLARIS && !defined(__hpux) && !defined(__sgi) */

/*ARGSUSED*/
int fr_nextfrag(token, itp, top, tail, lock, ifs)
ipftoken_t *token;
ipfgeniter_t *itp;
ipfr_t **top, ***tail;
ipfrwlock_t *lock;
ipf_stack_t *ifs;
{
        ipfr_t *frag, *next, zero;
        int error = 0;

        READ_ENTER(lock);

        /*
         * Retrieve "previous" entry from token and find the next entry.
         */
        frag = token->ipt_data;
        if (frag == NULL)
                next = *top;
        else
                next = frag->ipfr_next;

        /*
         * If we found an entry, add reference to it and update token.
         * Otherwise, zero out data to be returned and NULL out token.
         */
        if (next != NULL) {
                ATOMIC_INC(next->ipfr_ref);
                token->ipt_data = next;
        } else {
                bzero(&zero, sizeof(zero));
                next = &zero;
                token->ipt_data = NULL;
        }

        /*
         * Now that we have ref, it's save to give up lock.
         */
        RWLOCK_EXIT(lock);

        /*
         * Copy out data and clean up references and token as needed.
         */
        error = COPYOUT(next, itp->igi_data, sizeof(*next));
        if (error != 0)
                error = EFAULT;
        if (token->ipt_data == NULL) {
                ipf_freetoken(token, ifs);
        } else {
                if (frag != NULL)
                        fr_fragderef(&frag, lock, ifs);
                if (next->ipfr_next == NULL)
                        ipf_freetoken(token, ifs);
        }
        return error;
}


void fr_fragderef(frp, lock, ifs)
ipfr_t **frp;
ipfrwlock_t *lock;
ipf_stack_t *ifs;
{
        ipfr_t *fra;

        fra = *frp;
        *frp = NULL;

        WRITE_ENTER(lock);
        fra->ipfr_ref--;
        if (fra->ipfr_ref <= 0) {
                KFREE(fra);
                ifs->ifs_ipfr_stats.ifs_expire++;
                ifs->ifs_ipfr_inuse--;
        }
        RWLOCK_EXIT(lock);
}