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

 /*
  * Copyright (C) 1995-2001 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/param.h>
 #if defined(__hpux) && (HPUXREV >= 1111) && !defined(_KERNEL)
 # include <sys/kern_svcs.h>
 #endif
 #include <sys/types.h>
 #include <sys/time.h>
 #include <sys/errno.h>
 #if !defined(_KERNEL)
 # include <stdlib.h>
 # include <string.h>
 # define _KERNEL
 # ifdef __OpenBSD__
 struct file;
 # endif
 # include <sys/uio.h>
 # undef _KERNEL
 #else
 # include <sys/systm.h>
 # if !defined(__svr4__) && !defined(__SVR4)
 #  include <sys/mbuf.h>
 # endif
 #endif
 #include <sys/socket.h>
 #if !defined(__hpux) && !defined(__osf__) && !defined(linux) && !defined(AIX)
 # include <sys/ioccom.h>
 #endif
 #ifdef __FreeBSD__
 # include <sys/filio.h>
 # include <sys/malloc.h>
 #else
 # include <sys/ioctl.h>
 #endif

 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
 #include <netinet/tcp.h>

 #include <net/if.h>


 #include "netinet/ip_compat.h"
 #include "netinet/ip_fil.h"
 #include "netinet/ip_state.h"
 #include "netinet/ip_scan.h"
 /* 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[] = "@(#)$Id$";
 #endif

 #ifdef	IPFILTER_SCAN	/* endif at bottom of file */


 ipscan_t	*ipsc_list = NULL,
 		*ipsc_tail = NULL;
 ipscanstat_t	ipsc_stat;
 # ifdef USE_MUTEXES
 ipfrwlock_t	ipsc_rwlock;
 # endif

 # ifndef isalpha
 #  define	isalpha(x)	(((x) >= 'A' && 'Z' >= (x)) || \
 				 ((x) >= 'a' && 'z' >= (x)))
 # endif


 int ipsc_add __P((caddr_t));
 int ipsc_delete __P((caddr_t));
 struct ipscan *ipsc_lookup __P((char *));
 int ipsc_matchstr __P((sinfo_t *, char *, int));
 int ipsc_matchisc __P((ipscan_t *, ipstate_t *, int, int, int *));
 int ipsc_match __P((ipstate_t *));

 static int	ipsc_inited = 0;


 int ipsc_init()
 {
 	RWLOCK_INIT(&ipsc_rwlock, "ip scan rwlock");
 	ipsc_inited = 1;
 	return 0;
 }


 void fr_scanunload()
 {
 	if (ipsc_inited == 1) {
 		RW_DESTROY(&ipsc_rwlock);
 		ipsc_inited = 0;
 	}
 }


 int ipsc_add(data)
 caddr_t data;
 {
 	ipscan_t *i, *isc;
 	int err;

 	KMALLOC(isc, ipscan_t *);
 	if (!isc)
 		return ENOMEM;

 	err = copyinptr(data, isc, sizeof(*isc));
 	if (err) {
 		KFREE(isc);
 		return err;
 	}

 	WRITE_ENTER(&ipsc_rwlock);

 	i = ipsc_lookup(isc->ipsc_tag);
 	if (i) {
 		RWLOCK_EXIT(&ipsc_rwlock);
 		KFREE(isc);
 		return EEXIST;
 	}

 	if (ipsc_tail) {
 		ipsc_tail->ipsc_next = isc;
 		isc->ipsc_pnext = &ipsc_tail->ipsc_next;
 		ipsc_tail = isc;
 	} else {
 		ipsc_list = isc;
 		ipsc_tail = isc;
 		isc->ipsc_pnext = &ipsc_list;
 	}
 	isc->ipsc_next = NULL;

 	isc->ipsc_hits = 0;
 	isc->ipsc_fref = 0;
 	isc->ipsc_sref = 0;
 	isc->ipsc_active = 0;

 	ipsc_stat.iscs_entries++;
 	RWLOCK_EXIT(&ipsc_rwlock);
 	return 0;
 }


 int ipsc_delete(data)
 caddr_t data;
 {
 	ipscan_t isc, *i;
 	int err;

 	err = copyinptr(data, &isc, sizeof(isc));
 	if (err)
 		return err;

 	WRITE_ENTER(&ipsc_rwlock);

 	i = ipsc_lookup(isc.ipsc_tag);
 	if (i == NULL)
 		err = ENOENT;
 	else {
 		if (i->ipsc_fref) {
 			RWLOCK_EXIT(&ipsc_rwlock);
 			return EBUSY;
 		}

 		*i->ipsc_pnext = i->ipsc_next;
 		if (i->ipsc_next)
 			i->ipsc_next->ipsc_pnext = i->ipsc_pnext;
 		else {
 			if (i->ipsc_pnext == &ipsc_list)
 				ipsc_tail = NULL;
 			else
 				ipsc_tail = *(*i->ipsc_pnext)->ipsc_pnext;
 		}

 		ipsc_stat.iscs_entries--;
 		KFREE(i);
 	}
 	RWLOCK_EXIT(&ipsc_rwlock);
 	return err;
 }


 struct ipscan *ipsc_lookup(tag)
 char *tag;
 {
 	ipscan_t *i;

 	for (i = ipsc_list; i; i = i->ipsc_next)
 		if (!strcmp(i->ipsc_tag, tag))
 			return i;
 	return NULL;
 }


 int ipsc_attachfr(fr)
 struct frentry *fr;
 {
 	ipscan_t *i;

 	if (fr->fr_isctag[0]) {
 		READ_ENTER(&ipsc_rwlock);
 		i = ipsc_lookup(fr->fr_isctag);
 		if (i != NULL) {
 			ATOMIC_INC32(i->ipsc_fref);
 		}
 		RWLOCK_EXIT(&ipsc_rwlock);
 		if (i == NULL)
 			return ENOENT;
 		fr->fr_isc = i;
 	}
 	return 0;
 }


 int ipsc_attachis(is)
 struct ipstate *is;
 {
 	frentry_t *fr;
 	ipscan_t *i;

 	READ_ENTER(&ipsc_rwlock);
 	fr = is->is_rule;
 	if (fr) {
 		i = fr->fr_isc;
 		if ((i != NULL) && (i != (ipscan_t *)-1)) {
 			is->is_isc = i;
 			ATOMIC_INC32(i->ipsc_sref);
 			if (i->ipsc_clen)
 				is->is_flags |= IS_SC_CLIENT;
 			else
 				is->is_flags |= IS_SC_MATCHC;
 			if (i->ipsc_slen)
 				is->is_flags |= IS_SC_SERVER;
 			else
 				is->is_flags |= IS_SC_MATCHS;
 		}
 	}
 	RWLOCK_EXIT(&ipsc_rwlock);
 	return 0;
 }


 int ipsc_detachfr(fr)
 struct frentry *fr;
 {
 	ipscan_t *i;

 	i = fr->fr_isc;
 	if (i != NULL) {
 		ATOMIC_DEC32(i->ipsc_fref);
 	}
 	return 0;
 }


 int ipsc_detachis(is)
 struct ipstate *is;
 {
 	ipscan_t *i;

 	READ_ENTER(&ipsc_rwlock);
 	if ((i = is->is_isc) && (i != (ipscan_t *)-1)) {
 		ATOMIC_DEC32(i->ipsc_sref);
 		is->is_isc = NULL;
 		is->is_flags &= ~(IS_SC_CLIENT|IS_SC_SERVER);
 	}
 	RWLOCK_EXIT(&ipsc_rwlock);
 	return 0;
 }


 /*
  * 'string' compare for scanning
  */
 int ipsc_matchstr(sp, str, n)
 sinfo_t *sp;
 char *str;
 int n;
 {
 	char *s, *t, *up;
 	int i = n;

 	if (i > sp->s_len)
 		i = sp->s_len;
 	up = str;

 	for (s = sp->s_txt, t = sp->s_msk; i; i--, s++, t++, up++)
 		switch ((int)*t)
 		{
 		case '.' :
 			if (*s != *up)
 				return 1;
 			break;
 		case '?' :
 			if (!ISALPHA(*up) || ((*s & 0x5f) != (*up & 0x5f)))
 				return 1;
 			break;
 		case '*' :
 			break;
 		}
 	return 0;
 }


 /*
  * Returns 3 if both server and client match, 2 if just server,
  * 1 if just client
  */
 int ipsc_matchisc(isc, is, cl, sl, maxm)
 ipscan_t *isc;
 ipstate_t *is;
 int cl, sl, maxm[2];
 {
 	int i, j, k, n, ret = 0, flags;

 	flags = is->is_flags;

 	/*
 	 * If we've already matched more than what is on offer, then
 	 * assume we have a better match already and forget this one.
 	 */
 	if (maxm != NULL) {
 		if (isc->ipsc_clen < maxm[0])
 			return 0;
 		if (isc->ipsc_slen < maxm[1])
 			return 0;
 		j = maxm[0];
 		k = maxm[1];
 	} else {
 		j = 0;
 		k = 0;
 	}

 	if (!isc->ipsc_clen)
 		ret = 1;
 	else if (((flags & (IS_SC_MATCHC|IS_SC_CLIENT)) == IS_SC_CLIENT) &&
 		 cl && isc->ipsc_clen) {
 		i = 0;
 		n = MIN(cl, isc->ipsc_clen);
 		if ((n > 0) && (!maxm || (n >= maxm[1]))) {
 			if (!ipsc_matchstr(&isc->ipsc_cl, is->is_sbuf[0], n)) {
 				i++;
 				ret |= 1;
 				if (n > j)
 					j = n;
 			}
 		}
 	}

 	if (!isc->ipsc_slen)
 		ret |= 2;
 	else if (((flags & (IS_SC_MATCHS|IS_SC_SERVER)) == IS_SC_SERVER) &&
 		 sl && isc->ipsc_slen) {
 		i = 0;
 		n = MIN(cl, isc->ipsc_slen);
 		if ((n > 0) && (!maxm || (n >= maxm[1]))) {
 			if (!ipsc_matchstr(&isc->ipsc_sl, is->is_sbuf[1], n)) {
 				i++;
 				ret |= 2;
 				if (n > k)
 					k = n;
 			}
 		}
 	}

 	if (maxm && (ret == 3)) {
 		maxm[0] = j;
 		maxm[1] = k;
 	}
 	return ret;
 }


 int ipsc_match(is)
 ipstate_t *is;
 {
 	int i, j, k, n, cl, sl, maxm[2];
 	ipscan_t *isc, *lm;
 	tcpdata_t *t;

 	for (cl = 0, n = is->is_smsk[0]; n & 1; n >>= 1)
 		cl++;
 	for (sl = 0, n = is->is_smsk[1]; n & 1; n >>= 1)
 		sl++;

 	j = 0;
 	isc = is->is_isc;
 	if (isc != NULL) {
 		/*
 		 * Known object to scan for.
 		 */
 		i = ipsc_matchisc(isc, is, cl, sl, NULL);
 		if (i & 1) {
 			is->is_flags |= IS_SC_MATCHC;
 			is->is_flags &= ~IS_SC_CLIENT;
 		} else if (cl >= isc->ipsc_clen)
 			is->is_flags &= ~IS_SC_CLIENT;
 		if (i & 2) {
 			is->is_flags |= IS_SC_MATCHS;
 			is->is_flags &= ~IS_SC_SERVER;
 		} else if (sl >= isc->ipsc_slen)
 			is->is_flags &= ~IS_SC_SERVER;
 	} else {
 		i = 0;
 		lm = NULL;
 		maxm[0] = 0;
 		maxm[1] = 0;
 		for (k = 0, isc = ipsc_list; isc; isc = isc->ipsc_next) {
 			i = ipsc_matchisc(isc, is, cl, sl, maxm);
 			if (i) {
 				/*
 				 * We only want to remember the best match
 				 * and the number of times we get a best
 				 * match.
 				 */
 				if ((j == 3) && (i < 3))
 					continue;
 				if ((i == 3) && (j != 3))
 					k = 1;
 				else
 					k++;
 				j = i;
 				lm = isc;
 			}
 		}
 		if (k == 1)
 			isc = lm;
 		if (isc == NULL)
 			return 0;

 		/*
 		 * No matches or partial matches, so reset the respective
 		 * search flag.
 		 */
 		if (!(j & 1))
 			is->is_flags &= ~IS_SC_CLIENT;

 		if (!(j & 2))
 			is->is_flags &= ~IS_SC_SERVER;

 		/*
 		 * If we found the best match, then set flags appropriately.
 		 */
 		if ((j == 3) && (k == 1)) {
 			is->is_flags &= ~(IS_SC_SERVER|IS_SC_CLIENT);
 			is->is_flags |= (IS_SC_MATCHS|IS_SC_MATCHC);
 		}
 	}

 	/*
 	 * If the acknowledged side of a connection has moved past the data in
 	 * which we are interested, then reset respective flag.
 	 */
 	t = &is->is_tcp.ts_data[0];
 	if (t->td_end > is->is_s0[0] + 15)
 		is->is_flags &= ~IS_SC_CLIENT;

 	t = &is->is_tcp.ts_data[1];
 	if (t->td_end > is->is_s0[1] + 15)
 		is->is_flags &= ~IS_SC_SERVER;

 	/*
 	 * Matching complete ?
 	 */
 	j = ISC_A_NONE;
 	if ((is->is_flags & IS_SC_MATCHALL) == IS_SC_MATCHALL) {
 		j = isc->ipsc_action;
 		ipsc_stat.iscs_acted++;
 	} else if ((is->is_isc != NULL) &&
 		   ((is->is_flags & IS_SC_MATCHALL) != IS_SC_MATCHALL) &&
 		   !(is->is_flags & (IS_SC_CLIENT|IS_SC_SERVER))) {
 		/*
 		 * Matching failed...
 		 */
 		j = isc->ipsc_else;
 		ipsc_stat.iscs_else++;
 	}

 	switch (j)
 	{
 	case  ISC_A_CLOSE :
 		/*
 		 * If as a result of a successful match we are to
 		 * close a connection, change the "keep state" info.
 		 * to block packets and generate TCP RST's.
 		 */
 		is->is_pass &= ~FR_RETICMP;
 		is->is_pass |= FR_RETRST;
 		break;
 	default :
 		break;
 	}

 	return i;
 }


 /*
  * check if a packet matches what we're scanning for
  */
 int ipsc_packet(fin, is)
 fr_info_t *fin;
 ipstate_t *is;
 {
 	int i, j, rv, dlen, off, thoff;
 	u_32_t seq, s0;
 	tcphdr_t *tcp;

 	rv = !IP6_EQ(&fin->fin_fi.fi_src, &is->is_src);
 	tcp = fin->fin_dp;
 	seq = ntohl(tcp->th_seq);

 	if (!is->is_s0[rv])
 		return 1;

 	/*
 	 * check if this packet has more data that falls within the first
 	 * 16 bytes sent in either direction.
 	 */
 	s0 = is->is_s0[rv];
 	off = seq - s0;
 	if ((off > 15) || (off < 0))
 		return 1;
 	thoff = TCP_OFF(tcp) << 2;
 	dlen = fin->fin_dlen - thoff;
 	if (dlen <= 0)
 		return 1;
 	if (dlen > 16)
 		dlen = 16;
 	if (off + dlen > 16)
 		dlen = 16 - off;

 	j = 0xffff >> (16 - dlen);
 	i = (0xffff & j) << off;
 #ifdef _KERNEL
 	COPYDATA(*(mb_t **)fin->fin_mp, fin->fin_plen - fin->fin_dlen + thoff,
 		 dlen, (caddr_t)is->is_sbuf[rv] + off);
 #endif
 	is->is_smsk[rv] |= i;
 	for (j = 0, i = is->is_smsk[rv]; i & 1; i >>= 1)
 		j++;
 	if (j == 0)
 		return 1;

 	(void) ipsc_match(is);
 #if 0
 	/*
 	 * There is the potential here for plain text passwords to get
 	 * buffered and stored for some time...
 	 */
 	if (!(is->is_flags & IS_SC_CLIENT))
 		bzero(is->is_sbuf[0], sizeof(is->is_sbuf[0]));
 	if (!(is->is_flags & IS_SC_SERVER))
 		bzero(is->is_sbuf[1], sizeof(is->is_sbuf[1]));
 #endif
 	return 0;
 }


 int fr_scan_ioctl(data, cmd, mode, uid, ctx)
 caddr_t data;
 ioctlcmd_t cmd;
 int mode, uid;
 void *ctx;
 {
 	ipscanstat_t ipscs;
 	int err = 0;

 	switch (cmd)
 	{
 	case SIOCADSCA :
 		err = ipsc_add(data);
 		break;
 	case SIOCRMSCA :
 		err = ipsc_delete(data);
 		break;
 	case SIOCGSCST :
 		bcopy((char *)&ipsc_stat, (char *)&ipscs, sizeof(ipscs));
 		ipscs.iscs_list = ipsc_list;
 		BCOPYOUT(&ipscs, data, sizeof(ipscs));
 		break;
 	default :
 		err = EINVAL;
 		break;
 	}

 	return err;
 }
 #endif	/* IPFILTER_SCAN */
	/*
	* Copyright (C) 1995-2001 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/param.h>
	#if defined(__hpux) && (HPUXREV >= 1111) && !defined(_KERNEL)
	# include <sys/kern_svcs.h>
	#endif
	#include <sys/types.h>
	#include <sys/time.h>
	#include <sys/errno.h>
	#if !defined(_KERNEL)
	# include <stdlib.h>
	# include <string.h>
	# define _KERNEL
	# ifdef __OpenBSD__
	struct file;
	# endif
	# include <sys/uio.h>
	# undef _KERNEL
	#else
	# include <sys/systm.h>
	# if !defined(__svr4__) && !defined(__SVR4)
	# include <sys/mbuf.h>
	# endif
	#endif
	#include <sys/socket.h>
	#if !defined(__hpux) && !defined(__osf__) && !defined(linux) && !defined(AIX)
	# include <sys/ioccom.h>
	#endif
	#ifdef __FreeBSD__
	# include <sys/filio.h>
	# include <sys/malloc.h>
	#else
	# include <sys/ioctl.h>
	#endif

	#include <netinet/in.h>
	#include <netinet/in_systm.h>
	#include <netinet/ip.h>
	#include <netinet/tcp.h>

	#include <net/if.h>


	#include "netinet/ip_compat.h"
	#include "netinet/ip_fil.h"
	#include "netinet/ip_state.h"
	#include "netinet/ip_scan.h"
	/* 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[] = "@(#)$Id$";
	#endif

	#ifdef IPFILTER_SCAN /* endif at bottom of file */


	ipscan_t *ipsc_list = NULL,
	*ipsc_tail = NULL;
	ipscanstat_t ipsc_stat;
	# ifdef USE_MUTEXES
	ipfrwlock_t ipsc_rwlock;
	# endif

	# ifndef isalpha
	# define isalpha(x) (((x) >= 'A' && 'Z' >= (x)) \|\| \
	((x) >= 'a' && 'z' >= (x)))
	# endif


	int ipsc_add __P((caddr_t));
	int ipsc_delete __P((caddr_t));
	struct ipscan ipsc_lookup __P((char ));
	int ipsc_matchstr __P((sinfo_t , char , int));
	int ipsc_matchisc __P((ipscan_t , ipstate_t , int, int, int *));
	int ipsc_match __P((ipstate_t *));

	static int ipsc_inited = 0;


	int ipsc_init()
	{
	RWLOCK_INIT(&ipsc_rwlock, "ip scan rwlock");
	ipsc_inited = 1;
	return 0;
	}


	void fr_scanunload()
	{
	if (ipsc_inited == 1) {
	RW_DESTROY(&ipsc_rwlock);
	ipsc_inited = 0;
	}
	}


	int ipsc_add(data)
	caddr_t data;
	{
	ipscan_t i, isc;
	int err;

	KMALLOC(isc, ipscan_t *);
	if (!isc)
	return ENOMEM;

	err = copyinptr(data, isc, sizeof(*isc));
	if (err) {
	KFREE(isc);
	return err;
	}

	WRITE_ENTER(&ipsc_rwlock);

	i = ipsc_lookup(isc->ipsc_tag);
	if (i) {
	RWLOCK_EXIT(&ipsc_rwlock);
	KFREE(isc);
	return EEXIST;
	}

	if (ipsc_tail) {
	ipsc_tail->ipsc_next = isc;
	isc->ipsc_pnext = &ipsc_tail->ipsc_next;
	ipsc_tail = isc;
	} else {
	ipsc_list = isc;
	ipsc_tail = isc;
	isc->ipsc_pnext = &ipsc_list;
	}
	isc->ipsc_next = NULL;

	isc->ipsc_hits = 0;
	isc->ipsc_fref = 0;
	isc->ipsc_sref = 0;
	isc->ipsc_active = 0;

	ipsc_stat.iscs_entries++;
	RWLOCK_EXIT(&ipsc_rwlock);
	return 0;
	}


	int ipsc_delete(data)
	caddr_t data;
	{
	ipscan_t isc, *i;
	int err;

	err = copyinptr(data, &isc, sizeof(isc));
	if (err)
	return err;

	WRITE_ENTER(&ipsc_rwlock);

	i = ipsc_lookup(isc.ipsc_tag);
	if (i == NULL)
	err = ENOENT;
	else {
	if (i->ipsc_fref) {
	RWLOCK_EXIT(&ipsc_rwlock);
	return EBUSY;
	}

	*i->ipsc_pnext = i->ipsc_next;
	if (i->ipsc_next)
	i->ipsc_next->ipsc_pnext = i->ipsc_pnext;
	else {
	if (i->ipsc_pnext == &ipsc_list)
	ipsc_tail = NULL;
	else
	ipsc_tail = (i->ipsc_pnext)->ipsc_pnext;
	}

	ipsc_stat.iscs_entries--;
	KFREE(i);
	}
	RWLOCK_EXIT(&ipsc_rwlock);
	return err;
	}


	struct ipscan *ipsc_lookup(tag)
	char *tag;
	{
	ipscan_t *i;

	for (i = ipsc_list; i; i = i->ipsc_next)
	if (!strcmp(i->ipsc_tag, tag))
	return i;
	return NULL;
	}


	int ipsc_attachfr(fr)
	struct frentry *fr;
	{
	ipscan_t *i;

	if (fr->fr_isctag[0]) {
	READ_ENTER(&ipsc_rwlock);
	i = ipsc_lookup(fr->fr_isctag);
	if (i != NULL) {
	ATOMIC_INC32(i->ipsc_fref);
	}
	RWLOCK_EXIT(&ipsc_rwlock);
	if (i == NULL)
	return ENOENT;
	fr->fr_isc = i;
	}
	return 0;
	}


	int ipsc_attachis(is)
	struct ipstate *is;
	{
	frentry_t *fr;
	ipscan_t *i;

	READ_ENTER(&ipsc_rwlock);
	fr = is->is_rule;
	if (fr) {
	i = fr->fr_isc;
	if ((i != NULL) && (i != (ipscan_t *)-1)) {
	is->is_isc = i;
	ATOMIC_INC32(i->ipsc_sref);
	if (i->ipsc_clen)
	is->is_flags \|= IS_SC_CLIENT;
	else
	is->is_flags \|= IS_SC_MATCHC;
	if (i->ipsc_slen)
	is->is_flags \|= IS_SC_SERVER;
	else
	is->is_flags \|= IS_SC_MATCHS;
	}
	}
	RWLOCK_EXIT(&ipsc_rwlock);
	return 0;
	}


	int ipsc_detachfr(fr)
	struct frentry *fr;
	{
	ipscan_t *i;

	i = fr->fr_isc;
	if (i != NULL) {
	ATOMIC_DEC32(i->ipsc_fref);
	}
	return 0;
	}


	int ipsc_detachis(is)
	struct ipstate *is;
	{
	ipscan_t *i;

	READ_ENTER(&ipsc_rwlock);
	if ((i = is->is_isc) && (i != (ipscan_t *)-1)) {
	ATOMIC_DEC32(i->ipsc_sref);
	is->is_isc = NULL;
	is->is_flags &= ~(IS_SC_CLIENT\|IS_SC_SERVER);
	}
	RWLOCK_EXIT(&ipsc_rwlock);
	return 0;
	}


	/*
	* 'string' compare for scanning
	*/
	int ipsc_matchstr(sp, str, n)
	sinfo_t *sp;
	char *str;
	int n;
	{
	char s, t, *up;
	int i = n;

	if (i > sp->s_len)
	i = sp->s_len;
	up = str;

	for (s = sp->s_txt, t = sp->s_msk; i; i--, s++, t++, up++)
	switch ((int)*t)
	{
	case '.' :
	if (s != up)
	return 1;
	break;
	case '?' :
	if (!ISALPHA(up) \|\| ((s & 0x5f) != (*up & 0x5f)))
	return 1;
	break;
	case '*' :
	break;
	}
	return 0;
	}


	/*
	* Returns 3 if both server and client match, 2 if just server,
	* 1 if just client
	*/
	int ipsc_matchisc(isc, is, cl, sl, maxm)
	ipscan_t *isc;
	ipstate_t *is;
	int cl, sl, maxm[2];
	{
	int i, j, k, n, ret = 0, flags;

	flags = is->is_flags;

	/*
	* If we've already matched more than what is on offer, then
	* assume we have a better match already and forget this one.
	*/
	if (maxm != NULL) {
	if (isc->ipsc_clen < maxm[0])
	return 0;
	if (isc->ipsc_slen < maxm[1])
	return 0;
	j = maxm[0];
	k = maxm[1];
	} else {
	j = 0;
	k = 0;
	}

	if (!isc->ipsc_clen)
	ret = 1;
	else if (((flags & (IS_SC_MATCHC\|IS_SC_CLIENT)) == IS_SC_CLIENT) &&
	cl && isc->ipsc_clen) {
	i = 0;
	n = MIN(cl, isc->ipsc_clen);
	if ((n > 0) && (!maxm \|\| (n >= maxm[1]))) {
	if (!ipsc_matchstr(&isc->ipsc_cl, is->is_sbuf[0], n)) {
	i++;
	ret \|= 1;
	if (n > j)
	j = n;
	}
	}
	}

	if (!isc->ipsc_slen)
	ret \|= 2;
	else if (((flags & (IS_SC_MATCHS\|IS_SC_SERVER)) == IS_SC_SERVER) &&
	sl && isc->ipsc_slen) {
	i = 0;
	n = MIN(cl, isc->ipsc_slen);
	if ((n > 0) && (!maxm \|\| (n >= maxm[1]))) {
	if (!ipsc_matchstr(&isc->ipsc_sl, is->is_sbuf[1], n)) {
	i++;
	ret \|= 2;
	if (n > k)
	k = n;
	}
	}
	}

	if (maxm && (ret == 3)) {
	maxm[0] = j;
	maxm[1] = k;
	}
	return ret;
	}


	int ipsc_match(is)
	ipstate_t *is;
	{
	int i, j, k, n, cl, sl, maxm[2];
	ipscan_t isc, lm;
	tcpdata_t *t;

	for (cl = 0, n = is->is_smsk[0]; n & 1; n >>= 1)
	cl++;
	for (sl = 0, n = is->is_smsk[1]; n & 1; n >>= 1)
	sl++;

	j = 0;
	isc = is->is_isc;
	if (isc != NULL) {
	/*
	* Known object to scan for.
	*/
	i = ipsc_matchisc(isc, is, cl, sl, NULL);
	if (i & 1) {
	is->is_flags \|= IS_SC_MATCHC;
	is->is_flags &= ~IS_SC_CLIENT;
	} else if (cl >= isc->ipsc_clen)
	is->is_flags &= ~IS_SC_CLIENT;
	if (i & 2) {
	is->is_flags \|= IS_SC_MATCHS;
	is->is_flags &= ~IS_SC_SERVER;
	} else if (sl >= isc->ipsc_slen)
	is->is_flags &= ~IS_SC_SERVER;
	} else {
	i = 0;
	lm = NULL;
	maxm[0] = 0;
	maxm[1] = 0;
	for (k = 0, isc = ipsc_list; isc; isc = isc->ipsc_next) {
	i = ipsc_matchisc(isc, is, cl, sl, maxm);
	if (i) {
	/*
	* We only want to remember the best match
	* and the number of times we get a best
	* match.
	*/
	if ((j == 3) && (i < 3))
	continue;
	if ((i == 3) && (j != 3))
	k = 1;
	else
	k++;
	j = i;
	lm = isc;
	}
	}
	if (k == 1)
	isc = lm;
	if (isc == NULL)
	return 0;

	/*
	* No matches or partial matches, so reset the respective
	* search flag.
	*/
	if (!(j & 1))
	is->is_flags &= ~IS_SC_CLIENT;

	if (!(j & 2))
	is->is_flags &= ~IS_SC_SERVER;

	/*
	* If we found the best match, then set flags appropriately.
	*/
	if ((j == 3) && (k == 1)) {
	is->is_flags &= ~(IS_SC_SERVER\|IS_SC_CLIENT);
	is->is_flags \|= (IS_SC_MATCHS\|IS_SC_MATCHC);
	}
	}

	/*
	* If the acknowledged side of a connection has moved past the data in
	* which we are interested, then reset respective flag.
	*/
	t = &is->is_tcp.ts_data[0];
	if (t->td_end > is->is_s0[0] + 15)
	is->is_flags &= ~IS_SC_CLIENT;

	t = &is->is_tcp.ts_data[1];
	if (t->td_end > is->is_s0[1] + 15)
	is->is_flags &= ~IS_SC_SERVER;

	/*
	* Matching complete ?
	*/
	j = ISC_A_NONE;
	if ((is->is_flags & IS_SC_MATCHALL) == IS_SC_MATCHALL) {
	j = isc->ipsc_action;
	ipsc_stat.iscs_acted++;
	} else if ((is->is_isc != NULL) &&
	((is->is_flags & IS_SC_MATCHALL) != IS_SC_MATCHALL) &&
	!(is->is_flags & (IS_SC_CLIENT\|IS_SC_SERVER))) {
	/*
	* Matching failed...
	*/
	j = isc->ipsc_else;
	ipsc_stat.iscs_else++;
	}

	switch (j)
	{
	case ISC_A_CLOSE :
	/*
	* If as a result of a successful match we are to
	* close a connection, change the "keep state" info.
	* to block packets and generate TCP RST's.
	*/
	is->is_pass &= ~FR_RETICMP;
	is->is_pass \|= FR_RETRST;
	break;
	default :
	break;
	}

	return i;
	}


	/*
	* check if a packet matches what we're scanning for
	*/
	int ipsc_packet(fin, is)
	fr_info_t *fin;
	ipstate_t *is;
	{
	int i, j, rv, dlen, off, thoff;
	u_32_t seq, s0;
	tcphdr_t *tcp;

	rv = !IP6_EQ(&fin->fin_fi.fi_src, &is->is_src);
	tcp = fin->fin_dp;
	seq = ntohl(tcp->th_seq);

	if (!is->is_s0[rv])
	return 1;

	/*
	* check if this packet has more data that falls within the first
	* 16 bytes sent in either direction.
	*/
	s0 = is->is_s0[rv];
	off = seq - s0;
	if ((off > 15) \|\| (off < 0))
	return 1;
	thoff = TCP_OFF(tcp) << 2;
	dlen = fin->fin_dlen - thoff;
	if (dlen <= 0)
	return 1;
	if (dlen > 16)
	dlen = 16;
	if (off + dlen > 16)
	dlen = 16 - off;

	j = 0xffff >> (16 - dlen);
	i = (0xffff & j) << off;
	#ifdef _KERNEL
	COPYDATA((mb_t *)fin->fin_mp, fin->fin_plen - fin->fin_dlen + thoff,
	dlen, (caddr_t)is->is_sbuf[rv] + off);
	#endif
	is->is_smsk[rv] \|= i;
	for (j = 0, i = is->is_smsk[rv]; i & 1; i >>= 1)
	j++;
	if (j == 0)
	return 1;

	(void) ipsc_match(is);
	#if 0
	/*
	* There is the potential here for plain text passwords to get
	* buffered and stored for some time...
	*/
	if (!(is->is_flags & IS_SC_CLIENT))
	bzero(is->is_sbuf[0], sizeof(is->is_sbuf[0]));
	if (!(is->is_flags & IS_SC_SERVER))
	bzero(is->is_sbuf[1], sizeof(is->is_sbuf[1]));
	#endif
	return 0;
	}


	int fr_scan_ioctl(data, cmd, mode, uid, ctx)
	caddr_t data;
	ioctlcmd_t cmd;
	int mode, uid;
	void *ctx;
	{
	ipscanstat_t ipscs;
	int err = 0;

	switch (cmd)
	{
	case SIOCADSCA :
	err = ipsc_add(data);
	break;
	case SIOCRMSCA :
	err = ipsc_delete(data);
	break;
	case SIOCGSCST :
	bcopy((char )&ipsc_stat, (char )&ipscs, sizeof(ipscs));
	ipscs.iscs_list = ipsc_list;
	BCOPYOUT(&ipscs, data, sizeof(ipscs));
	break;
	default :
	err = EINVAL;
	break;
	}

	return err;
	}
	#endif /* IPFILTER_SCAN */