ip_frag.c - net/ipfilter - Rivoreo Source Code Repositories

 /*
  * Copyright (C) 1993-2000 by Darren Reed.
  *
  * Redistribution and use in source and binary forms are permitted
  * provided that this notice is preserved and due credit is given
  * to the original author and the contributors.
  */
 #if !defined(lint)
 static const char sccsid[] = "@(#)ip_frag.c	1.11 3/24/96 (C) 1993-2000 Darren Reed";
 static const char rcsid[] = "@(#)$Id$";
 #endif

 #if defined(KERNEL) && !defined(_KERNEL)
 # define      _KERNEL
 #endif

 #include <sys/errno.h>
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/time.h>
 #include <sys/file.h>
 #if !defined(_KERNEL) && !defined(KERNEL)
 # include <stdio.h>
 # include <string.h>
 # include <stdlib.h>
 #endif
 #if defined(KERNEL) && (__FreeBSD_version >= 220000)
 # include <sys/filio.h>
 # include <sys/fcntl.h>
 #else
 # include <sys/ioctl.h>
 #endif
 #include <sys/uio.h>
 #ifndef linux
 # include <sys/protosw.h>
 #endif
 #include <sys/socket.h>
 #if defined(_KERNEL) && !defined(linux)
 # include <sys/systm.h>
 #endif
 #if !defined(__SVR4) && !defined(__svr4__)
 # if defined(_KERNEL) && !defined(__sgi)
 #  include <sys/kernel.h>
 # endif
 # ifndef linux
 #  include <sys/mbuf.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>
 #ifndef 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_proxy.h"
 #include "netinet/ip_nat.h"
 #include "netinet/ip_frag.h"
 #include "netinet/ip_state.h"
 #include "netinet/ip_auth.h"
 #if (__FreeBSD_version >= 300000)
 # include <sys/malloc.h>
 # if (defined(KERNEL) || defined(_KERNEL))
 #  ifndef IPFILTER_LKM
 #   include <sys/libkern.h>
 #   include <sys/systm.h>
 # endif
 extern struct callout_handle ipfr_slowtimer_ch;
 # endif
 #endif


 static ipfr_t	*ipfr_heads[IPFT_SIZE];
 static ipfr_t	*ipfr_nattab[IPFT_SIZE];
 static ipfrstat_t ipfr_stats;
 static int	ipfr_inuse = 0;

 int	fr_ipfrttl = 120;	/* 60 seconds */
 int	fr_frag_lock = 0;

 #ifdef _KERNEL
 # if SOLARIS2 >= 7
 extern	timeout_id_t	ipfr_timer_id;
 # else
 extern	int	ipfr_timer_id;
 # endif
 #endif
 #if	(SOLARIS || defined(__sgi)) && defined(_KERNEL)
 extern	KRWLOCK_T	ipf_frag, ipf_natfrag, ipf_nat, ipf_mutex;
 # if	SOLARIS
 extern	KRWLOCK_T	ipf_solaris;
 # else
 KRWLOCK_T	ipf_solaris;
 # endif
 extern	kmutex_t	ipf_rw;
 #endif


 static ipfr_t *ipfr_new __P((ip_t *, fr_info_t *, u_int, ipfr_t **));
 static ipfr_t *ipfr_lookup __P((ip_t *, fr_info_t *, ipfr_t **));
 static void ipfr_delete __P((ipfr_t *));


 ipfrstat_t *ipfr_fragstats()
 {
 	ipfr_stats.ifs_table = ipfr_heads;
 	ipfr_stats.ifs_nattab = ipfr_nattab;
 	ipfr_stats.ifs_inuse = ipfr_inuse;
 	return &ipfr_stats;
 }


 /*
  * 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_new(ip, fin, pass, table)
 ip_t *ip;
 fr_info_t *fin;
 u_int pass;
 ipfr_t *table[];
 {
 	ipfr_t	**fp, *fra, frag;
 	u_int	idx;

 	frag.ipfr_p = ip->ip_p;
 	idx = ip->ip_p;
 	frag.ipfr_id = ip->ip_id;
 	idx += ip->ip_id;
 	frag.ipfr_tos = ip->ip_tos;
 	frag.ipfr_src.s_addr = ip->ip_src.s_addr;
 	idx += ip->ip_src.s_addr;
 	frag.ipfr_dst.s_addr = ip->ip_dst.s_addr;
 	idx += ip->ip_dst.s_addr;
 	idx *= 127;
 	idx %= IPFT_SIZE;

 	/*
 	 * first, make sure it isn't already there...
 	 */
 	for (fp = &table[idx]; (fra = *fp); fp = &fra->ipfr_next)
 		if (!bcmp((char *)&frag.ipfr_src, (char *)&fra->ipfr_src,
 			  IPFR_CMPSZ)) {
 			ATOMIC_INCL(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) {
 		ATOMIC_INCL(ipfr_stats.ifs_nomem);
 		return NULL;
 	}

 	if ((fra->ipfr_rule = fin->fin_fr) != NULL) {
 		ATOMIC_INC32(fin->fin_fr->fr_ref);
 	}


 	/*
 	 * Instert 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 and mask out logging from "pass"
 	 */
 	if ((fra->ipfr_next = table[idx]))
 		table[idx]->ipfr_prev = fra;
 	fra->ipfr_prev = NULL;
 	fra->ipfr_data = NULL;
 	table[idx] = fra;
 	bcopy((char *)&frag.ipfr_src, (char *)&fra->ipfr_src, IPFR_CMPSZ);
 	fra->ipfr_ttl = fr_ipfrttl;
 	/*
 	 * Compute the offset of the expected start of the next packet.
 	 */
 	fra->ipfr_off = (ip->ip_off & IP_OFFMASK) + (fin->fin_dlen >> 3);
 	ATOMIC_INCL(ipfr_stats.ifs_new);
 	ATOMIC_INC32(ipfr_inuse);
 	return fra;
 }


 int ipfr_newfrag(ip, fin, pass)
 ip_t *ip;
 fr_info_t *fin;
 u_int pass;
 {
 	ipfr_t	*ipf;

 	if ((ip->ip_v != 4) || (fr_frag_lock))
 		return NULL;
 	WRITE_ENTER(&ipf_frag);
 	ipf = ipfr_new(ip, fin, pass, ipfr_heads);
 	RWLOCK_EXIT(&ipf_frag);
 	return ipf ? 0 : -1;
 }


 int ipfr_nat_newfrag(ip, fin, pass, nat)
 ip_t *ip;
 fr_info_t *fin;
 u_int pass;
 nat_t *nat;
 {
 	ipfr_t	*ipf;

 	if ((ip->ip_v != 4) || (fr_frag_lock))
 		return NULL;
 	WRITE_ENTER(&ipf_natfrag);
 	ipf = ipfr_new(ip, fin, pass, ipfr_nattab);
 	if (ipf != NULL) {
 		ipf->ipfr_data = nat;
 		nat->nat_data = ipf;
 	}
 	RWLOCK_EXIT(&ipf_natfrag);
 	return ipf ? 0 : -1;
 }


 /*
  * check the fragment cache to see if there is already a record of this packet
  * with its filter result known.
  */
 static ipfr_t *ipfr_lookup(ip, fin, table)
 ip_t *ip;
 fr_info_t *fin;
 ipfr_t *table[];
 {
 	ipfr_t	*f, 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.
 	 */
 	frag.ipfr_p = ip->ip_p;
 	idx = ip->ip_p;
 	frag.ipfr_id = ip->ip_id;
 	idx += ip->ip_id;
 	frag.ipfr_tos = ip->ip_tos;
 	frag.ipfr_src.s_addr = ip->ip_src.s_addr;
 	idx += ip->ip_src.s_addr;
 	frag.ipfr_dst.s_addr = ip->ip_dst.s_addr;
 	idx += ip->ip_dst.s_addr;
 	idx *= 127;
 	idx %= IPFT_SIZE;

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

 			if (f != table[idx]) {
 				/*
 				 * move fragment info. to the top of the list
 				 * to speed up searches.
 				 */
 				if ((f->ipfr_prev->ipfr_next = f->ipfr_next))
 					f->ipfr_next->ipfr_prev = f->ipfr_prev;
 				f->ipfr_next = table[idx];
 				table[idx]->ipfr_prev = f;
 				f->ipfr_prev = NULL;
 				table[idx] = f;
 			}
 			off = ip->ip_off & IP_OFFMASK;
 			atoff = off + (fin->fin_dlen >> 3);
 			/*
 			 * If we've follwed the fragments, and this is the
 			 * last (in order), shrink expiration time.
 			 */
 			if (off == f->ipfr_off) {
 				if (!(ip->ip_off & IP_MF))
 					f->ipfr_ttl = 1;
 				else
 					f->ipfr_off = atoff;
 			}
 			ATOMIC_INCL(ipfr_stats.ifs_hits);
 			return f;
 		}
 	return NULL;
 }


 /*
  * functional interface for NAT lookups of the NAT fragment cache
  */
 nat_t *ipfr_nat_knownfrag(ip, fin)
 ip_t *ip;
 fr_info_t *fin;
 {
 	nat_t	*nat;
 	ipfr_t	*ipf;

 	if ((ip->ip_v != 4) || (fr_frag_lock))
 		return NULL;
 	READ_ENTER(&ipf_natfrag);
 	ipf = ipfr_lookup(ip, fin, ipfr_nattab);
 	if (ipf != NULL) {
 		nat = ipf->ipfr_data;
 		/*
 		 * This is the last fragment for this packet.
 		 */
 		if ((ipf->ipfr_ttl == 1) && (nat != NULL)) {
 			nat->nat_data = NULL;
 			ipf->ipfr_data = NULL;
 		}
 	} else
 		nat = NULL;
 	RWLOCK_EXIT(&ipf_natfrag);
 	return nat;
 }


 /*
  * functional interface for normal lookups of the fragment cache
  */
 frentry_t *ipfr_knownfrag(ip, fin)
 ip_t *ip;
 fr_info_t *fin;
 {
 	frentry_t *fr = NULL;
 	ipfr_t	*fra;

 	if ((ip->ip_v != 4) || (fr_frag_lock))
 		return NULL;
 	READ_ENTER(&ipf_frag);
 	fra = ipfr_lookup(ip, fin, ipfr_heads);
 	if (fra != NULL)
 		fr = fra->ipfr_rule;
 	RWLOCK_EXIT(&ipf_frag);
 	return fr;
 }


 /*
  * forget any references to this external object.
  */
 void ipfr_forget(nat)
 void *nat;
 {
 	ipfr_t	*fr;
 	int	idx;

 	WRITE_ENTER(&ipf_natfrag);
 	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
 		for (fr = ipfr_heads[idx]; fr; fr = fr->ipfr_next)
 			if (fr->ipfr_data == nat)
 				fr->ipfr_data = NULL;

 	RWLOCK_EXIT(&ipf_natfrag);
 }


 static void ipfr_delete(fra)
 ipfr_t *fra;
 {
 	frentry_t *fr;

 	fr = fra->ipfr_rule;
 	if (fr != NULL) {
 		ATOMIC_DEC32(fr->fr_ref);
 		if (fr->fr_ref == 0)
 			KFREE(fr);
 	}
 	if (fra->ipfr_prev)
 		fra->ipfr_prev->ipfr_next = fra->ipfr_next;
 	if (fra->ipfr_next)
 		fra->ipfr_next->ipfr_prev = fra->ipfr_prev;
 	KFREE(fra);
 }


 /*
  * Free memory in use by fragment state info. kept.
  */
 void ipfr_unload()
 {
 	ipfr_t	**fp, *fra;
 	nat_t	*nat;
 	int	idx;

 	WRITE_ENTER(&ipf_frag);
 	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
 		for (fp = &ipfr_heads[idx]; (fra = *fp); ) {
 			*fp = fra->ipfr_next;
 			ipfr_delete(fra);
 		}
 	RWLOCK_EXIT(&ipf_frag);

 	WRITE_ENTER(&ipf_nat);
 	WRITE_ENTER(&ipf_natfrag);
 	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
 		for (fp = &ipfr_nattab[idx]; (fra = *fp); ) {
 			*fp = fra->ipfr_next;
 			nat = fra->ipfr_data;
 			if (nat != NULL) {
 				if (nat->nat_data == fra)
 					nat->nat_data = NULL;
 			}
 			ipfr_delete(fra);
 		}
 	RWLOCK_EXIT(&ipf_natfrag);
 	RWLOCK_EXIT(&ipf_nat);
 }


 #ifdef	_KERNEL
 void ipfr_fragexpire()
 {
 	ipfr_t	**fp, *fra;
 	nat_t	*nat;
 	int	idx;
 #if defined(_KERNEL)
 # if !SOLARIS
 	int	s;
 # endif
 #endif

 	if (fr_frag_lock)
 		return;

 	SPL_NET(s);
 	WRITE_ENTER(&ipf_frag);

 	/*
 	 * Go through the entire table, looking for entries to expire,
 	 * decreasing the ttl by one for each entry.  If it reaches 0,
 	 * remove it from the chain and free it.
 	 */
 	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
 		for (fp = &ipfr_heads[idx]; (fra = *fp); ) {
 			--fra->ipfr_ttl;
 			if (fra->ipfr_ttl == 0) {
 				*fp = fra->ipfr_next;
 				ipfr_delete(fra);
 				ATOMIC_INCL(ipfr_stats.ifs_expire);
 				ATOMIC_DEC32(ipfr_inuse);
 			} else
 				fp = &fra->ipfr_next;
 		}
 	RWLOCK_EXIT(&ipf_frag);

 	/*
 	 * 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(&ipf_nat);
 	WRITE_ENTER(&ipf_natfrag);
 	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
 		for (fp = &ipfr_nattab[idx]; (fra = *fp); ) {
 			--fra->ipfr_ttl;
 			if (fra->ipfr_ttl == 0) {
 				ATOMIC_INCL(ipfr_stats.ifs_expire);
 				ATOMIC_DEC32(ipfr_inuse);
 				nat = fra->ipfr_data;
 				if (nat != NULL) {
 					if (nat->nat_data == fra)
 						nat->nat_data = NULL;
 				}
 				*fp = fra->ipfr_next;
 				ipfr_delete(fra);
 			} else
 				fp = &fra->ipfr_next;
 		}
 	RWLOCK_EXIT(&ipf_natfrag);
 	RWLOCK_EXIT(&ipf_nat);
 	SPL_X(s);
 }


 /*
  * Slowly expire held state for fragments.  Timeouts are set * in expectation
  * of this being called twice per second.
  */
 # if (BSD >= 199306) || SOLARIS || defined(__sgi)
 #  if defined(SOLARIS2) && (SOLARIS2 < 7)
 void ipfr_slowtimer()
 #  else
 void ipfr_slowtimer __P((void *ptr))
 #  endif
 # else
 int ipfr_slowtimer()
 # endif
 {
 #if defined(_KERNEL) && SOLARIS
 	extern	int	fr_running;

 	if (fr_running <= 0)
 		return;
 #endif

 	READ_ENTER(&ipf_solaris);
 #ifdef __sgi
 	ipfilter_sgi_intfsync();
 #endif

 	ipfr_fragexpire();
 	fr_timeoutstate();
 	ip_natexpire();
 	fr_authexpire();
 # if	SOLARIS
 	ipfr_timer_id = timeout(ipfr_slowtimer, NULL, drv_usectohz(500000));
 # else
 #  ifndef linux
 #   if (__FreeBSD_version >= 300000)
 	ipfr_slowtimer_ch = timeout(ipfr_slowtimer, NULL, hz/2);
 #   else
 	timeout(ipfr_slowtimer, NULL, hz/2);
 #   endif
 #  endif
 #  if (BSD < 199306) && !defined(__sgi)
 	return 0;
 #  endif
 # endif
 	RWLOCK_EXIT(&ipf_solaris);
 }
 #endif /* defined(_KERNEL) */
	/*
	* Copyright (C) 1993-2000 by Darren Reed.
	*
	* Redistribution and use in source and binary forms are permitted
	* provided that this notice is preserved and due credit is given
	* to the original author and the contributors.
	*/
	#if !defined(lint)
	static const char sccsid[] = "@(#)ip_frag.c 1.11 3/24/96 (C) 1993-2000 Darren Reed";
	static const char rcsid[] = "@(#)$Id$";
	#endif

	#if defined(KERNEL) && !defined(_KERNEL)
	# define _KERNEL
	#endif

	#include <sys/errno.h>
	#include <sys/types.h>
	#include <sys/param.h>
	#include <sys/time.h>
	#include <sys/file.h>
	#if !defined(_KERNEL) && !defined(KERNEL)
	# include <stdio.h>
	# include <string.h>
	# include <stdlib.h>
	#endif
	#if defined(KERNEL) && (__FreeBSD_version >= 220000)
	# include <sys/filio.h>
	# include <sys/fcntl.h>
	#else
	# include <sys/ioctl.h>
	#endif
	#include <sys/uio.h>
	#ifndef linux
	# include <sys/protosw.h>
	#endif
	#include <sys/socket.h>
	#if defined(_KERNEL) && !defined(linux)
	# include <sys/systm.h>
	#endif
	#if !defined(__SVR4) && !defined(__svr4__)
	# if defined(_KERNEL) && !defined(__sgi)
	# include <sys/kernel.h>
	# endif
	# ifndef linux
	# include <sys/mbuf.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>
	#ifndef 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_proxy.h"
	#include "netinet/ip_nat.h"
	#include "netinet/ip_frag.h"
	#include "netinet/ip_state.h"
	#include "netinet/ip_auth.h"
	#if (__FreeBSD_version >= 300000)
	# include <sys/malloc.h>
	# if (defined(KERNEL) \|\| defined(_KERNEL))
	# ifndef IPFILTER_LKM
	# include <sys/libkern.h>
	# include <sys/systm.h>
	# endif
	extern struct callout_handle ipfr_slowtimer_ch;
	# endif
	#endif


	static ipfr_t *ipfr_heads[IPFT_SIZE];
	static ipfr_t *ipfr_nattab[IPFT_SIZE];
	static ipfrstat_t ipfr_stats;
	static int ipfr_inuse = 0;

	int fr_ipfrttl = 120; /* 60 seconds */
	int fr_frag_lock = 0;

	#ifdef _KERNEL
	# if SOLARIS2 >= 7
	extern timeout_id_t ipfr_timer_id;
	# else
	extern int ipfr_timer_id;
	# endif
	#endif
	#if (SOLARIS \|\| defined(__sgi)) && defined(_KERNEL)
	extern KRWLOCK_T ipf_frag, ipf_natfrag, ipf_nat, ipf_mutex;
	# if SOLARIS
	extern KRWLOCK_T ipf_solaris;
	# else
	KRWLOCK_T ipf_solaris;
	# endif
	extern kmutex_t ipf_rw;
	#endif


	static ipfr_t ipfr_new __P((ip_t , fr_info_t , u_int, ipfr_t *));
	static ipfr_t ipfr_lookup __P((ip_t , fr_info_t , ipfr_t *));
	static void ipfr_delete __P((ipfr_t *));


	ipfrstat_t *ipfr_fragstats()
	{
	ipfr_stats.ifs_table = ipfr_heads;
	ipfr_stats.ifs_nattab = ipfr_nattab;
	ipfr_stats.ifs_inuse = ipfr_inuse;
	return &ipfr_stats;
	}


	/*
	* 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_new(ip, fin, pass, table)
	ip_t *ip;
	fr_info_t *fin;
	u_int pass;
	ipfr_t *table[];
	{
	ipfr_t *fp, fra, frag;
	u_int idx;

	frag.ipfr_p = ip->ip_p;
	idx = ip->ip_p;
	frag.ipfr_id = ip->ip_id;
	idx += ip->ip_id;
	frag.ipfr_tos = ip->ip_tos;
	frag.ipfr_src.s_addr = ip->ip_src.s_addr;
	idx += ip->ip_src.s_addr;
	frag.ipfr_dst.s_addr = ip->ip_dst.s_addr;
	idx += ip->ip_dst.s_addr;
	idx *= 127;
	idx %= IPFT_SIZE;

	/*
	* first, make sure it isn't already there...
	*/
	for (fp = &table[idx]; (fra = *fp); fp = &fra->ipfr_next)
	if (!bcmp((char )&frag.ipfr_src, (char )&fra->ipfr_src,
	IPFR_CMPSZ)) {
	ATOMIC_INCL(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) {
	ATOMIC_INCL(ipfr_stats.ifs_nomem);
	return NULL;
	}

	if ((fra->ipfr_rule = fin->fin_fr) != NULL) {
	ATOMIC_INC32(fin->fin_fr->fr_ref);
	}


	/*
	* Instert 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 and mask out logging from "pass"
	*/
	if ((fra->ipfr_next = table[idx]))
	table[idx]->ipfr_prev = fra;
	fra->ipfr_prev = NULL;
	fra->ipfr_data = NULL;
	table[idx] = fra;
	bcopy((char )&frag.ipfr_src, (char )&fra->ipfr_src, IPFR_CMPSZ);
	fra->ipfr_ttl = fr_ipfrttl;
	/*
	* Compute the offset of the expected start of the next packet.
	*/
	fra->ipfr_off = (ip->ip_off & IP_OFFMASK) + (fin->fin_dlen >> 3);
	ATOMIC_INCL(ipfr_stats.ifs_new);
	ATOMIC_INC32(ipfr_inuse);
	return fra;
	}


	int ipfr_newfrag(ip, fin, pass)
	ip_t *ip;
	fr_info_t *fin;
	u_int pass;
	{
	ipfr_t *ipf;

	if ((ip->ip_v != 4) \|\| (fr_frag_lock))
	return NULL;
	WRITE_ENTER(&ipf_frag);
	ipf = ipfr_new(ip, fin, pass, ipfr_heads);
	RWLOCK_EXIT(&ipf_frag);
	return ipf ? 0 : -1;
	}


	int ipfr_nat_newfrag(ip, fin, pass, nat)
	ip_t *ip;
	fr_info_t *fin;
	u_int pass;
	nat_t *nat;
	{
	ipfr_t *ipf;

	if ((ip->ip_v != 4) \|\| (fr_frag_lock))
	return NULL;
	WRITE_ENTER(&ipf_natfrag);
	ipf = ipfr_new(ip, fin, pass, ipfr_nattab);
	if (ipf != NULL) {
	ipf->ipfr_data = nat;
	nat->nat_data = ipf;
	}
	RWLOCK_EXIT(&ipf_natfrag);
	return ipf ? 0 : -1;
	}


	/*
	* check the fragment cache to see if there is already a record of this packet
	* with its filter result known.
	*/
	static ipfr_t *ipfr_lookup(ip, fin, table)
	ip_t *ip;
	fr_info_t *fin;
	ipfr_t *table[];
	{
	ipfr_t *f, 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.
	*/
	frag.ipfr_p = ip->ip_p;
	idx = ip->ip_p;
	frag.ipfr_id = ip->ip_id;
	idx += ip->ip_id;
	frag.ipfr_tos = ip->ip_tos;
	frag.ipfr_src.s_addr = ip->ip_src.s_addr;
	idx += ip->ip_src.s_addr;
	frag.ipfr_dst.s_addr = ip->ip_dst.s_addr;
	idx += ip->ip_dst.s_addr;
	idx *= 127;
	idx %= IPFT_SIZE;

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

	if (f != table[idx]) {
	/*
	* move fragment info. to the top of the list
	* to speed up searches.
	*/
	if ((f->ipfr_prev->ipfr_next = f->ipfr_next))
	f->ipfr_next->ipfr_prev = f->ipfr_prev;
	f->ipfr_next = table[idx];
	table[idx]->ipfr_prev = f;
	f->ipfr_prev = NULL;
	table[idx] = f;
	}
	off = ip->ip_off & IP_OFFMASK;
	atoff = off + (fin->fin_dlen >> 3);
	/*
	* If we've follwed the fragments, and this is the
	* last (in order), shrink expiration time.
	*/
	if (off == f->ipfr_off) {
	if (!(ip->ip_off & IP_MF))
	f->ipfr_ttl = 1;
	else
	f->ipfr_off = atoff;
	}
	ATOMIC_INCL(ipfr_stats.ifs_hits);
	return f;
	}
	return NULL;
	}


	/*
	* functional interface for NAT lookups of the NAT fragment cache
	*/
	nat_t *ipfr_nat_knownfrag(ip, fin)
	ip_t *ip;
	fr_info_t *fin;
	{
	nat_t *nat;
	ipfr_t *ipf;

	if ((ip->ip_v != 4) \|\| (fr_frag_lock))
	return NULL;
	READ_ENTER(&ipf_natfrag);
	ipf = ipfr_lookup(ip, fin, ipfr_nattab);
	if (ipf != NULL) {
	nat = ipf->ipfr_data;
	/*
	* This is the last fragment for this packet.
	*/
	if ((ipf->ipfr_ttl == 1) && (nat != NULL)) {
	nat->nat_data = NULL;
	ipf->ipfr_data = NULL;
	}
	} else
	nat = NULL;
	RWLOCK_EXIT(&ipf_natfrag);
	return nat;
	}


	/*
	* functional interface for normal lookups of the fragment cache
	*/
	frentry_t *ipfr_knownfrag(ip, fin)
	ip_t *ip;
	fr_info_t *fin;
	{
	frentry_t *fr = NULL;
	ipfr_t *fra;

	if ((ip->ip_v != 4) \|\| (fr_frag_lock))
	return NULL;
	READ_ENTER(&ipf_frag);
	fra = ipfr_lookup(ip, fin, ipfr_heads);
	if (fra != NULL)
	fr = fra->ipfr_rule;
	RWLOCK_EXIT(&ipf_frag);
	return fr;
	}


	/*
	* forget any references to this external object.
	*/
	void ipfr_forget(nat)
	void *nat;
	{
	ipfr_t *fr;
	int idx;

	WRITE_ENTER(&ipf_natfrag);
	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
	for (fr = ipfr_heads[idx]; fr; fr = fr->ipfr_next)
	if (fr->ipfr_data == nat)
	fr->ipfr_data = NULL;

	RWLOCK_EXIT(&ipf_natfrag);
	}


	static void ipfr_delete(fra)
	ipfr_t *fra;
	{
	frentry_t *fr;

	fr = fra->ipfr_rule;
	if (fr != NULL) {
	ATOMIC_DEC32(fr->fr_ref);
	if (fr->fr_ref == 0)
	KFREE(fr);
	}
	if (fra->ipfr_prev)
	fra->ipfr_prev->ipfr_next = fra->ipfr_next;
	if (fra->ipfr_next)
	fra->ipfr_next->ipfr_prev = fra->ipfr_prev;
	KFREE(fra);
	}


	/*
	* Free memory in use by fragment state info. kept.
	*/
	void ipfr_unload()
	{
	ipfr_t *fp, fra;
	nat_t *nat;
	int idx;

	WRITE_ENTER(&ipf_frag);
	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
	for (fp = &ipfr_heads[idx]; (fra = *fp); ) {
	*fp = fra->ipfr_next;
	ipfr_delete(fra);
	}
	RWLOCK_EXIT(&ipf_frag);

	WRITE_ENTER(&ipf_nat);
	WRITE_ENTER(&ipf_natfrag);
	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
	for (fp = &ipfr_nattab[idx]; (fra = *fp); ) {
	*fp = fra->ipfr_next;
	nat = fra->ipfr_data;
	if (nat != NULL) {
	if (nat->nat_data == fra)
	nat->nat_data = NULL;
	}
	ipfr_delete(fra);
	}
	RWLOCK_EXIT(&ipf_natfrag);
	RWLOCK_EXIT(&ipf_nat);
	}


	#ifdef _KERNEL
	void ipfr_fragexpire()
	{
	ipfr_t *fp, fra;
	nat_t *nat;
	int idx;
	#if defined(_KERNEL)
	# if !SOLARIS
	int s;
	# endif
	#endif

	if (fr_frag_lock)
	return;

	SPL_NET(s);
	WRITE_ENTER(&ipf_frag);

	/*
	* Go through the entire table, looking for entries to expire,
	* decreasing the ttl by one for each entry. If it reaches 0,
	* remove it from the chain and free it.
	*/
	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
	for (fp = &ipfr_heads[idx]; (fra = *fp); ) {
	--fra->ipfr_ttl;
	if (fra->ipfr_ttl == 0) {
	*fp = fra->ipfr_next;
	ipfr_delete(fra);
	ATOMIC_INCL(ipfr_stats.ifs_expire);
	ATOMIC_DEC32(ipfr_inuse);
	} else
	fp = &fra->ipfr_next;
	}
	RWLOCK_EXIT(&ipf_frag);

	/*
	* 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(&ipf_nat);
	WRITE_ENTER(&ipf_natfrag);
	for (idx = IPFT_SIZE - 1; idx >= 0; idx--)
	for (fp = &ipfr_nattab[idx]; (fra = *fp); ) {
	--fra->ipfr_ttl;
	if (fra->ipfr_ttl == 0) {
	ATOMIC_INCL(ipfr_stats.ifs_expire);
	ATOMIC_DEC32(ipfr_inuse);
	nat = fra->ipfr_data;
	if (nat != NULL) {
	if (nat->nat_data == fra)
	nat->nat_data = NULL;
	}
	*fp = fra->ipfr_next;
	ipfr_delete(fra);
	} else
	fp = &fra->ipfr_next;
	}
	RWLOCK_EXIT(&ipf_natfrag);
	RWLOCK_EXIT(&ipf_nat);
	SPL_X(s);
	}


	/*
	* Slowly expire held state for fragments. Timeouts are set * in expectation
	* of this being called twice per second.
	*/
	# if (BSD >= 199306) \|\| SOLARIS \|\| defined(__sgi)
	# if defined(SOLARIS2) && (SOLARIS2 < 7)
	void ipfr_slowtimer()
	# else
	void ipfr_slowtimer __P((void *ptr))
	# endif
	# else
	int ipfr_slowtimer()
	# endif
	{
	#if defined(_KERNEL) && SOLARIS
	extern int fr_running;

	if (fr_running <= 0)
	return;
	#endif

	READ_ENTER(&ipf_solaris);
	#ifdef __sgi
	ipfilter_sgi_intfsync();
	#endif

	ipfr_fragexpire();
	fr_timeoutstate();
	ip_natexpire();
	fr_authexpire();
	# if SOLARIS
	ipfr_timer_id = timeout(ipfr_slowtimer, NULL, drv_usectohz(500000));
	# else
	# ifndef linux
	# if (__FreeBSD_version >= 300000)
	ipfr_slowtimer_ch = timeout(ipfr_slowtimer, NULL, hz/2);
	# else
	timeout(ipfr_slowtimer, NULL, hz/2);
	# endif
	# endif
	# if (BSD < 199306) && !defined(__sgi)
	return 0;
	# endif
	# endif
	RWLOCK_EXIT(&ipf_solaris);
	}
	#endif /* defined(_KERNEL) */