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

 /*
  * Copyright (C) 1997-2003 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/time.h>
 #include <sys/file.h>
 #include <sys/fcntl.h>
 #if !defined(_KERNEL) && !defined(__KERNEL__)
 # include <stdio.h>
 # include <string.h>
 # include <stdlib.h>
 # include <ctype.h>
 # define _KERNEL
 # ifdef __OpenBSD__
 struct file;
 # endif
 # include <sys/uio.h>
 # undef _KERNEL
 #endif
 #if !defined(linux)
 # include <sys/protosw.h>
 #endif
 #include <sys/socket.h>
 #if defined(_KERNEL)
 # if !defined(__NetBSD__) && !defined(sun) && !defined(__osf__) && \
      !defined(__OpenBSD__) && !defined(__hpux) && !defined(__sgi)
 #  include <sys/ctype.h>
 # endif
 # include <sys/systm.h>
 # if !defined(__SVR4) && !defined(__svr4__)
 #  include <sys/mbuf.h>
 # endif
 #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
 #if defined(__SVR4) || defined(__svr4__)
 # include <sys/byteorder.h>
 # ifdef _KERNEL
 #  include <sys/dditypes.h>
 # endif
 # include <sys/stream.h>
 # include <sys/kmem.h>
 #endif
 #if __FreeBSD__ > 2
 # include <sys/queue.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_nat.h"
 #include "netinet/ip_state.h"
 #include "netinet/ip_proxy.h"
 #if (__FreeBSD_version >= 300000)
 # include <sys/malloc.h>
 #endif

 #include "netinet/ip_ftp_pxy.c"
 #if defined(_KERNEL)
 # include "netinet/ip_irc_pxy.c"
 # include "netinet/ip_rcmd_pxy.c"
 # include "netinet/ip_raudio_pxy.c"
 # include "netinet/ip_h323_pxy.c"
 # ifdef	IPFILTER_PRO
 #  include "netinet/ip_msnrpc_pxy.c"
 # endif
 # include "netinet/ip_netbios_pxy.c"
 #endif
 #include "netinet/ip_ipsec_pxy.c"
 #include "netinet/ip_rpcb_pxy.c"

 /* END OF INCLUDES */

 #if !defined(lint)
 static const char rcsid[] = "@(#)$Id$";
 #endif

 static int appr_fixseqack __P((fr_info_t *, ip_t *, ap_session_t *, int ));

 #define	AP_SESS_SIZE	53

 ap_session_t	*ap_sess_tab[AP_SESS_SIZE];
 ap_session_t	*ap_sess_list = NULL;
 aproxy_t	*ap_proxylist = NULL;
 aproxy_t	ap_proxies[] = {
 #ifdef	IPF_FTP_PROXY
 	{ NULL, "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, ippr_ftp_fini,
 	  ippr_ftp_new, NULL, ippr_ftp_in, ippr_ftp_out, NULL },
 #endif
 #ifdef	IPF_IRC_PROXY
 	{ NULL, "irc", (char)IPPROTO_TCP, 0, 0, ippr_irc_init, ippr_irc_fini,
 	  ippr_irc_new, NULL, NULL, ippr_irc_out, NULL, NULL },
 #endif
 #ifdef	IPF_RCMD_PROXY
 	{ NULL, "rcmd", (char)IPPROTO_TCP, 0, 0, ippr_rcmd_init, ippr_rcmd_fini,
 	  ippr_rcmd_new, NULL, ippr_rcmd_in, ippr_rcmd_out, NULL, NULL },
 #endif
 #ifdef	IPF_RAUDIO_PROXY
 	{ NULL, "raudio", (char)IPPROTO_TCP, 0, 0, ippr_raudio_init, ippr_raudio_fini,
 	  ippr_raudio_new, NULL, ippr_raudio_in, ippr_raudio_out, NULL, NULL },
 #endif
 #ifdef	IPF_MSNRPC_PROXY
 	{ NULL, "msnrpc", (char)IPPROTO_TCP, 0, 0, ippr_msnrpc_init, ippr_msnrpc_fini,
 	  ippr_msnrpc_new, NULL, ippr_msnrpc_in, ippr_msnrpc_out, NULL, NULL },
 #endif
 #ifdef	IPF_NETBIOS_PROXY
 	{ NULL, "netbios", (char)IPPROTO_UDP, 0, 0, ippr_netbios_init, ippr_netbios_fini,
 	  NULL, NULL, NULL, ippr_netbios_out, NULL, NULL },
 #endif
 #ifdef	IPF_IPSEC_PROXY
 	{ NULL, "ipsec", (char)IPPROTO_UDP, 0, 0,
 	  ippr_ipsec_init, ippr_ipsec_fini, ippr_ipsec_new, ippr_ipsec_del,
 	  NULL, ippr_ipsec_out, NULL, NULL },
 #endif
 #ifdef  IPF_H323_PROXY
 	{ NULL, "h323", (char)IPPROTO_TCP, 0, 0, ippr_h323_init, ippr_h323_fini,
 	  ippr_h323_new, ippr_h323_del, ippr_h323_in, NULL, NULL },
 	{ NULL, "h245", (char)IPPROTO_TCP, 0, 0, NULL, NULL,
 	  ippr_h245_new, NULL, NULL, ippr_h245_out, NULL },
 #endif
 #ifdef	IPF_RPCB_PROXY
 # if 0
 	{ NULL, "rpcbt", (char)IPPROTO_TCP, 0, 0,
 	  ippr_rpcb_init, ippr_rpcb_fini, ippr_rpcb_new, ippr_rpcb_del,
 	  ippr_rpcb_in, ippr_rpcb_out, NULL, NULL },
 # endif
 	{ NULL, "rpcbu", (char)IPPROTO_UDP, 0, 0,
 	  ippr_rpcb_init, ippr_rpcb_fini, ippr_rpcb_new, ippr_rpcb_del,
 	  ippr_rpcb_in, ippr_rpcb_out, NULL, NULL },
 #endif
 	{ NULL, "", '\0', 0, 0, NULL, NULL, NULL, NULL }
 };

 /*
  * Dynamically add a new kernel proxy.  Ensure that it is unique in the
  * collection compiled in and dynamically added.
  */
 int appr_add(ap)
 aproxy_t *ap;
 {
 	aproxy_t *a;

 	for (a = ap_proxies; a->apr_p; a++)
 		if ((a->apr_p == ap->apr_p) &&
 		    !strncmp(a->apr_label, ap->apr_label,
 			     sizeof(ap->apr_label)))
 			return -1;

 	for (a = ap_proxylist; a->apr_p; a = a->apr_next)
 		if ((a->apr_p == ap->apr_p) &&
 		    !strncmp(a->apr_label, ap->apr_label,
 			     sizeof(ap->apr_label)))
 			return -1;
 	ap->apr_next = ap_proxylist;
 	ap_proxylist = ap;
 	if (ap->apr_init != NULL)
 		return (*ap->apr_init)();
 	return 0;
 }


 /*
  * Check to see if the proxy this control request has come through for
  * exists, and if it does and it has a control function then invoke that
  * control function.
  */
 int appr_ctl(ctl)
 ap_ctl_t *ctl;
 {
 	aproxy_t *a;
 	int error;

 	a = appr_lookup(ctl->apc_p, ctl->apc_label);
 	if (a == NULL)
 		error = ESRCH;
 	else if (a->apr_ctl == NULL)
 		error = ENXIO;
 	else
 		error = (*a->apr_ctl)(a, ctl);
 	return error;
 }


 /*
  * Delete a proxy that has been added dynamically from those available.
  * If it is in use, return 1 (do not destroy NOW), not in use 0 or -1
  * if it cannot be matched.
  */
 int appr_del(ap)
 aproxy_t *ap;
 {
 	aproxy_t *a, **app;

 	for (app = &ap_proxylist; ((a = *app) != NULL); app = &a->apr_next)
 		if (a == ap) {
 			a->apr_flags |= APR_DELETE;
 			*app = a->apr_next;
 			if (ap->apr_ref != 0)
 				return 1;
 			return 0;
 		}
 	return -1;
 }


 /*
  * Return 1 if the packet is a good match against a proxy, else 0.
  */
 int appr_ok(fin, tcp, nat)
 fr_info_t *fin;
 tcphdr_t *tcp;
 ipnat_t *nat;
 {
 	aproxy_t *apr = nat->in_apr;
 	u_short dport = nat->in_dport;

 	if ((apr == NULL) || (apr->apr_flags & APR_DELETE) ||
 	    (fin->fin_p != apr->apr_p))
 		return 0;
 	if ((tcp == NULL) && dport)
 		return 0;
 	return 1;
 }


 int appr_ioctl(data, cmd, mode)
 caddr_t data;
 ioctlcmd_t cmd;
 int mode;
 {
 	ap_ctl_t ctl;
 	caddr_t ptr;
 	int error;

 	mode = mode;	/* LINT */

 	switch (cmd)
 	{
 	case SIOCPROXY :
 		BCOPYIN(data, &ctl, sizeof(ctl));
 		ptr = NULL;

 		if (ctl.apc_dsize > 0) {
 			KMALLOCS(ptr, caddr_t, ctl.apc_dsize);
 			if (ptr == NULL)
 				error = ENOMEM;
 			else {
 				error = copyinptr(ctl.apc_data, ptr,
 						  ctl.apc_dsize);
 				if (error == 0)
 					ctl.apc_data = ptr;
 			}
 		} else {
 			ctl.apc_data = NULL;
 			error = 0;
 		}

 		if (error == 0)
 			error = appr_ctl(&ctl);

 		if (ctl.apc_dsize > 0 && ptr != NULL && ctl.apc_data == ptr) {
 			KFREES(ptr, ctl.apc_dsize);
 		}
 		break;

 	default :
 		error = EINVAL;
 	}
 	return error;
 }


 /*
  * If a proxy has a match function, call that to do extended packet
  * matching.
  */
 int appr_match(fin, nat)
 fr_info_t *fin;
 nat_t *nat;
 {
 	aproxy_t *apr;
 	ipnat_t *ipn;

 	ipn = nat->nat_ptr;
 	if (ipn == NULL)
 		return -1;
 	apr = ipn->in_apr;
 	if ((apr == NULL) || (apr->apr_flags & APR_DELETE) ||
 	    (nat->nat_aps == NULL))
 		return -1;
 	if (apr->apr_match != NULL)
 		if ((*apr->apr_match)(fin, nat->nat_aps, nat) != 0)
 			return -1;
 	return 0;
 }


 /*
  * Allocate a new application proxy structure and fill it in with the
  * relevant details.  call the init function once complete, prior to
  * returning.
  */
 int appr_new(fin, nat)
 fr_info_t *fin;
 nat_t *nat;
 {
 	register ap_session_t *aps;
 	aproxy_t *apr;

 	if ((nat->nat_ptr == NULL) || (nat->nat_aps != NULL))
 		return -1;

 	apr = nat->nat_ptr->in_apr;

 	if (!apr || (apr->apr_flags & APR_DELETE) ||
 	    (fin->fin_p != apr->apr_p))
 		return -1;

 	KMALLOC(aps, ap_session_t *);
 	if (!aps)
 		return -1;
 	bzero((char *)aps, sizeof(*aps));
 	aps->aps_p = fin->fin_p;
 	aps->aps_data = NULL;
 	aps->aps_apr = apr;
 	aps->aps_psiz = 0;
 	if (apr->apr_new != NULL)
 		if ((*apr->apr_new)(fin, aps, nat) == -1) {
 			if ((aps->aps_data != NULL) && (aps->aps_psiz != 0)) {
 				KFREES(aps->aps_data, aps->aps_psiz);
 			}
 			KFREE(aps);
 			return -1;
 		}
 	aps->aps_nat = nat;
 	aps->aps_next = ap_sess_list;
 	ap_sess_list = aps;
 	nat->nat_aps = aps;

 	return 0;
 }


 /*
  * Check to see if a packet should be passed through an active proxy routine
  * if one has been setup for it.  We don't need to check the checksum here if
  * IPFILTER_CKSUM is defined because if it is, a failed check causes FI_BAD
  * to be set.
  */
 int appr_check(fin, nat)
 fr_info_t *fin;
 nat_t *nat;
 {
 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
 # if defined(ICK_VALID)
 	mb_t *m;
 # endif
 	int dosum = 1;
 #endif
 	tcphdr_t *tcp = NULL;
 	udphdr_t *udp = NULL;
 	ap_session_t *aps;
 	aproxy_t *apr;
 	ip_t *ip;
 	short rv;
 	int err;
 #if !defined(_KERNEL) || defined(MENTAT) || defined(__sgi)
 	u_32_t s1, s2, sd;
 #endif

 	if (fin->fin_flx & FI_BAD)
 		return -1;

 #ifndef IPFILTER_CKSUM
 	if ((fin->fin_out == 0) && (fr_checkl4sum(fin) == -1)) {
 # if PROXY_DEBUG || !defined(_KERNEL)
 		printf("proxy l4 checksum failure\n");
 # endif
 		if (fin->fin_p == IPPROTO_TCP)
 			frstats[fin->fin_out].fr_tcpbad++;
 		return -1;
 	}
 #endif

 	aps = nat->nat_aps;
 	if ((aps != NULL) && (aps->aps_p == fin->fin_p)) {
 		/*
 		 * If there is data in this packet to be proxied then try and
 		 * get it all into the one buffer, else drop it.
 		 */
 		if ((fin->fin_dlen > 0) && !(fin->fin_flx & FI_COALESCE))
 			if (fr_coalesce(fin) == -1)
 				return -1;
 		ip = fin->fin_ip;

 		switch (fin->fin_p)
 		{
 		case IPPROTO_TCP :
 			tcp = (tcphdr_t *)fin->fin_dp;

 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) && defined(ICK_VALID)
 			m = fin->fin_qfm;
 			if (dohwcksum && (m->b_ick_flag == ICK_VALID))
 				dosum = 0;
 #endif
 			/*
 			 * Don't bother the proxy with these...or in fact,
 			 * should we free up proxy stuff when seen?
 			 */
 			if ((fin->fin_tcpf & TH_RST) != 0)
 				break;
 			/*FALLTHROUGH*/
 		case IPPROTO_UDP :
 			udp = (udphdr_t *)fin->fin_dp;
 			break;
 		default :
 			break;
 		}

 		apr = aps->aps_apr;
 		err = 0;
 		if (fin->fin_out != 0) {
 			if (apr->apr_outpkt != NULL)
 				err = (*apr->apr_outpkt)(fin, aps, nat);
 		} else {
 			if (apr->apr_inpkt != NULL)
 				err = (*apr->apr_inpkt)(fin, aps, nat);
 		}

 		rv = APR_EXIT(err);
 		if (rv == 1) {
 #if PROXY_DEBUG || !defined(_KERNEL)
 			printf("proxy says bad packet received\n");
 #endif
 			return -1;
 		}
 		if (rv == 2) {
 #if PROXY_DEBUG || !defined(_KERNEL)
 			printf("proxy says free app proxy data\n");
 #endif
 			appr_free(apr);
 			nat->nat_aps = NULL;
 			return -1;
 		}

 		/*
 		 * If err != 0 then the data size of the packet has changed
 		 * so we need to recalculate the header checksums for the
 		 * packet.
 		 */
 #if !defined(_KERNEL) || defined(MENTAT) || defined(__sgi)
 		if (err != 0) {
 			short adjlen = err & 0xffff;

 			s1 = LONG_SUM(ip->ip_len - adjlen);
 			s2 = LONG_SUM(ip->ip_len);
 			CALC_SUMD(s1, s2, sd);
 			fix_outcksum(fin, &ip->ip_sum, sd);
 		}
 #endif

 		/*
 		 * For TCP packets, we may need to adjust the sequence and
 		 * acknowledgement numbers to reflect changes in size of the
 		 * data stream.
 		 *
 		 * For both TCP and UDP, recalculate the layer 4 checksum,
 		 * regardless, as we can't tell (here) if data has been
 		 * changed or not.
 		 */
 		if (tcp != NULL) {
 			err = appr_fixseqack(fin, ip, aps, APR_INC(err));
 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
 			if (dosum)
 				tcp->th_sum = fr_cksum(fin->fin_qfm, ip,
 						       IPPROTO_TCP, tcp);
 #else
 			tcp->th_sum = fr_cksum(fin->fin_m, ip,
 					       IPPROTO_TCP, tcp);
 #endif
 		} else if ((udp != NULL) && (udp->uh_sum != 0)) {
 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
 			if (dosum)
 				udp->uh_sum = fr_cksum(fin->fin_qfm, ip,
 						       IPPROTO_UDP, udp);
 #else
 			udp->uh_sum = fr_cksum(fin->fin_m, ip,
 					       IPPROTO_UDP, udp);
 #endif
 		}
 		aps->aps_bytes += fin->fin_plen;
 		aps->aps_pkts++;
 		return 1;
 	}
 	return 0;
 }


 /*
  * Search for an proxy by the protocol it is being used with and its name.
  */
 aproxy_t *appr_lookup(pr, name)
 u_int pr;
 char *name;
 {
 	aproxy_t *ap;

 	for (ap = ap_proxies; ap->apr_p; ap++)
 		if ((ap->apr_p == pr) &&
 		    !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
 			ap->apr_ref++;
 			return ap;
 		}

 	for (ap = ap_proxylist; ap; ap = ap->apr_next)
 		if ((ap->apr_p == pr) &&
 		    !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
 			ap->apr_ref++;
 			return ap;
 		}
 	return NULL;
 }


 void appr_free(ap)
 aproxy_t *ap;
 {
 	ap->apr_ref--;
 }


 void aps_free(aps)
 ap_session_t *aps;
 {
 	ap_session_t *a, **ap;
 	aproxy_t *apr;

 	if (!aps)
 		return;

 	for (ap = &ap_sess_list; ((a = *ap) != NULL); ap = &a->aps_next)
 		if (a == aps) {
 			*ap = a->aps_next;
 			break;
 		}

 	apr = aps->aps_apr;
 	if ((apr != NULL) && (apr->apr_del != NULL))
 		(*apr->apr_del)(aps);

 	if ((aps->aps_data != NULL) && (aps->aps_psiz != 0))
 		KFREES(aps->aps_data, aps->aps_psiz);
 	KFREE(aps);
 }


 /*
  * returns 2 if ack or seq number in TCP header is changed, returns 0 otherwise
  */
 static int appr_fixseqack(fin, ip, aps, inc)
 fr_info_t *fin;
 ip_t *ip;
 ap_session_t *aps;
 int inc;
 {
 	int sel, ch = 0, out, nlen;
 	u_32_t seq1, seq2;
 	tcphdr_t *tcp;
 	short inc2;

 	tcp = (tcphdr_t *)fin->fin_dp;
 	out = fin->fin_out;
 	/*
 	 * ip_len has already been adjusted by 'inc'.
 	 */
 	nlen = ip->ip_len;
 	nlen -= (IP_HL(ip) << 2) + (TCP_OFF(tcp) << 2);

 	inc2 = inc;
 	inc = (int)inc2;

 	if (out != 0) {
 		seq1 = (u_32_t)ntohl(tcp->th_seq);
 		sel = aps->aps_sel[out];

 		/* switch to other set ? */
 		if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
 		    (seq1 > aps->aps_seqmin[!sel])) {
 #if PROXY_DEBUG
 			printf("proxy out switch set seq %d -> %d %x > %x\n",
 				sel, !sel, seq1, aps->aps_seqmin[!sel]);
 #endif
 			sel = aps->aps_sel[out] = !sel;
 		}

 		if (aps->aps_seqoff[sel]) {
 			seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel];
 			if (seq1 > seq2) {
 				seq2 = aps->aps_seqoff[sel];
 				seq1 += seq2;
 				tcp->th_seq = htonl(seq1);
 				ch = 1;
 			}
 		}

 		if (inc && (seq1 > aps->aps_seqmin[!sel])) {
 			aps->aps_seqmin[sel] = seq1 + nlen - 1;
 			aps->aps_seqoff[sel] = aps->aps_seqoff[sel] + inc;
 #if PROXY_DEBUG
 			printf("proxy seq set %d at %x to %d + %d\n", sel,
 				aps->aps_seqmin[sel], aps->aps_seqoff[sel],
 				inc);
 #endif
 		}

 		/***/

 		seq1 = ntohl(tcp->th_ack);
 		sel = aps->aps_sel[1 - out];

 		/* switch to other set ? */
 		if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
 		    (seq1 > aps->aps_ackmin[!sel])) {
 #if PROXY_DEBUG
 			printf("proxy out switch set ack %d -> %d %x > %x\n",
 				sel, !sel, seq1, aps->aps_ackmin[!sel]);
 #endif
 			sel = aps->aps_sel[1 - out] = !sel;
 		}

 		if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) {
 			seq2 = aps->aps_ackoff[sel];
 			tcp->th_ack = htonl(seq1 - seq2);
 			ch = 1;
 		}
 	} else {
 		seq1 = ntohl(tcp->th_seq);
 		sel = aps->aps_sel[out];

 		/* switch to other set ? */
 		if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
 		    (seq1 > aps->aps_ackmin[!sel])) {
 #if PROXY_DEBUG
 			printf("proxy in switch set ack %d -> %d %x > %x\n",
 				sel, !sel, seq1, aps->aps_ackmin[!sel]);
 #endif
 			sel = aps->aps_sel[out] = !sel;
 		}

 		if (aps->aps_ackoff[sel]) {
 			seq2 = aps->aps_ackmin[sel] - aps->aps_ackoff[sel];
 			if (seq1 > seq2) {
 				seq2 = aps->aps_ackoff[sel];
 				seq1 += seq2;
 				tcp->th_seq = htonl(seq1);
 				ch = 1;
 			}
 		}

 		if (inc && (seq1 > aps->aps_ackmin[!sel])) {
 			aps->aps_ackmin[!sel] = seq1 + nlen - 1;
 			aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc;
 #if PROXY_DEBUG
 			printf("proxy ack set %d at %x to %d + %d\n", !sel,
 				aps->aps_seqmin[!sel], aps->aps_seqoff[sel],
 				inc);
 #endif
 		}

 		/***/

 		seq1 = ntohl(tcp->th_ack);
 		sel = aps->aps_sel[1 - out];

 		/* switch to other set ? */
 		if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
 		    (seq1 > aps->aps_seqmin[!sel])) {
 #if PROXY_DEBUG
 			printf("proxy in switch set seq %d -> %d %x > %x\n",
 				sel, !sel, seq1, aps->aps_seqmin[!sel]);
 #endif
 			sel = aps->aps_sel[1 - out] = !sel;
 		}

 		if (aps->aps_seqoff[sel] != 0) {
 #if PROXY_DEBUG
 			printf("sel %d seqoff %d seq1 %x seqmin %x\n", sel,
 				aps->aps_seqoff[sel], seq1,
 				aps->aps_seqmin[sel]);
 #endif
 			if (seq1 > aps->aps_seqmin[sel]) {
 				seq2 = aps->aps_seqoff[sel];
 				tcp->th_ack = htonl(seq1 - seq2);
 				ch = 1;
 			}
 		}
 	}
 #if PROXY_DEBUG
 	printf("appr_fixseqack: seq %lx ack %lx\n", ntohl(tcp->th_seq),
 		ntohl(tcp->th_ack));
 #endif
 	return ch ? 2 : 0;
 }


 /*
  * Initialise hook for kernel application proxies.
  * Call the initialise routine for all the compiled in kernel proxies.
  */
 int appr_init()
 {
 	aproxy_t *ap;
 	int err = 0;

 	for (ap = ap_proxies; ap->apr_p; ap++) {
 		if (ap->apr_init != NULL) {
 			err = (*ap->apr_init)();
 			if (err != 0)
 				break;
 		}
 	}
 	return err;
 }


 /*
  * Unload hook for kernel application proxies.
  * Call the finialise routine for all the compiled in kernel proxies.
  */
 void appr_unload()
 {
 	aproxy_t *ap;

 	for (ap = ap_proxies; ap->apr_p; ap++)
 		if (ap->apr_fini != NULL)
 			(*ap->apr_fini)();
 	for (ap = ap_proxylist; ap; ap = ap->apr_next)
 		if (ap->apr_fini != NULL)
 			(*ap->apr_fini)();
 }
	/*
	* Copyright (C) 1997-2003 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/time.h>
	#include <sys/file.h>
	#include <sys/fcntl.h>
	#if !defined(_KERNEL) && !defined(__KERNEL__)
	# include <stdio.h>
	# include <string.h>
	# include <stdlib.h>
	# include <ctype.h>
	# define _KERNEL
	# ifdef __OpenBSD__
	struct file;
	# endif
	# include <sys/uio.h>
	# undef _KERNEL
	#endif
	#if !defined(linux)
	# include <sys/protosw.h>
	#endif
	#include <sys/socket.h>
	#if defined(_KERNEL)
	# if !defined(__NetBSD__) && !defined(sun) && !defined(__osf__) && \
	!defined(__OpenBSD__) && !defined(__hpux) && !defined(__sgi)
	# include <sys/ctype.h>
	# endif
	# include <sys/systm.h>
	# if !defined(__SVR4) && !defined(__svr4__)
	# include <sys/mbuf.h>
	# endif
	#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
	#if defined(__SVR4) \|\| defined(__svr4__)
	# include <sys/byteorder.h>
	# ifdef _KERNEL
	# include <sys/dditypes.h>
	# endif
	# include <sys/stream.h>
	# include <sys/kmem.h>
	#endif
	#if __FreeBSD__ > 2
	# include <sys/queue.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_nat.h"
	#include "netinet/ip_state.h"
	#include "netinet/ip_proxy.h"
	#if (__FreeBSD_version >= 300000)
	# include <sys/malloc.h>
	#endif

	#include "netinet/ip_ftp_pxy.c"
	#if defined(_KERNEL)
	# include "netinet/ip_irc_pxy.c"
	# include "netinet/ip_rcmd_pxy.c"
	# include "netinet/ip_raudio_pxy.c"
	# include "netinet/ip_h323_pxy.c"
	# ifdef IPFILTER_PRO
	# include "netinet/ip_msnrpc_pxy.c"
	# endif
	# include "netinet/ip_netbios_pxy.c"
	#endif
	#include "netinet/ip_ipsec_pxy.c"
	#include "netinet/ip_rpcb_pxy.c"

	/* END OF INCLUDES */

	#if !defined(lint)
	static const char rcsid[] = "@(#)$Id$";
	#endif

	static int appr_fixseqack __P((fr_info_t , ip_t , ap_session_t *, int ));

	#define AP_SESS_SIZE 53

	ap_session_t *ap_sess_tab[AP_SESS_SIZE];
	ap_session_t *ap_sess_list = NULL;
	aproxy_t *ap_proxylist = NULL;
	aproxy_t ap_proxies[] = {
	#ifdef IPF_FTP_PROXY
	{ NULL, "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, ippr_ftp_fini,
	ippr_ftp_new, NULL, ippr_ftp_in, ippr_ftp_out, NULL },
	#endif
	#ifdef IPF_IRC_PROXY
	{ NULL, "irc", (char)IPPROTO_TCP, 0, 0, ippr_irc_init, ippr_irc_fini,
	ippr_irc_new, NULL, NULL, ippr_irc_out, NULL, NULL },
	#endif
	#ifdef IPF_RCMD_PROXY
	{ NULL, "rcmd", (char)IPPROTO_TCP, 0, 0, ippr_rcmd_init, ippr_rcmd_fini,
	ippr_rcmd_new, NULL, ippr_rcmd_in, ippr_rcmd_out, NULL, NULL },
	#endif
	#ifdef IPF_RAUDIO_PROXY
	{ NULL, "raudio", (char)IPPROTO_TCP, 0, 0, ippr_raudio_init, ippr_raudio_fini,
	ippr_raudio_new, NULL, ippr_raudio_in, ippr_raudio_out, NULL, NULL },
	#endif
	#ifdef IPF_MSNRPC_PROXY
	{ NULL, "msnrpc", (char)IPPROTO_TCP, 0, 0, ippr_msnrpc_init, ippr_msnrpc_fini,
	ippr_msnrpc_new, NULL, ippr_msnrpc_in, ippr_msnrpc_out, NULL, NULL },
	#endif
	#ifdef IPF_NETBIOS_PROXY
	{ NULL, "netbios", (char)IPPROTO_UDP, 0, 0, ippr_netbios_init, ippr_netbios_fini,
	NULL, NULL, NULL, ippr_netbios_out, NULL, NULL },
	#endif
	#ifdef IPF_IPSEC_PROXY
	{ NULL, "ipsec", (char)IPPROTO_UDP, 0, 0,
	ippr_ipsec_init, ippr_ipsec_fini, ippr_ipsec_new, ippr_ipsec_del,
	NULL, ippr_ipsec_out, NULL, NULL },
	#endif
	#ifdef IPF_H323_PROXY
	{ NULL, "h323", (char)IPPROTO_TCP, 0, 0, ippr_h323_init, ippr_h323_fini,
	ippr_h323_new, ippr_h323_del, ippr_h323_in, NULL, NULL },
	{ NULL, "h245", (char)IPPROTO_TCP, 0, 0, NULL, NULL,
	ippr_h245_new, NULL, NULL, ippr_h245_out, NULL },
	#endif
	#ifdef IPF_RPCB_PROXY
	# if 0
	{ NULL, "rpcbt", (char)IPPROTO_TCP, 0, 0,
	ippr_rpcb_init, ippr_rpcb_fini, ippr_rpcb_new, ippr_rpcb_del,
	ippr_rpcb_in, ippr_rpcb_out, NULL, NULL },
	# endif
	{ NULL, "rpcbu", (char)IPPROTO_UDP, 0, 0,
	ippr_rpcb_init, ippr_rpcb_fini, ippr_rpcb_new, ippr_rpcb_del,
	ippr_rpcb_in, ippr_rpcb_out, NULL, NULL },
	#endif
	{ NULL, "", '\0', 0, 0, NULL, NULL, NULL, NULL }
	};

	/*
	* Dynamically add a new kernel proxy. Ensure that it is unique in the
	* collection compiled in and dynamically added.
	*/
	int appr_add(ap)
	aproxy_t *ap;
	{
	aproxy_t *a;

	for (a = ap_proxies; a->apr_p; a++)
	if ((a->apr_p == ap->apr_p) &&
	!strncmp(a->apr_label, ap->apr_label,
	sizeof(ap->apr_label)))
	return -1;

	for (a = ap_proxylist; a->apr_p; a = a->apr_next)
	if ((a->apr_p == ap->apr_p) &&
	!strncmp(a->apr_label, ap->apr_label,
	sizeof(ap->apr_label)))
	return -1;
	ap->apr_next = ap_proxylist;
	ap_proxylist = ap;
	if (ap->apr_init != NULL)
	return (*ap->apr_init)();
	return 0;
	}


	/*
	* Check to see if the proxy this control request has come through for
	* exists, and if it does and it has a control function then invoke that
	* control function.
	*/
	int appr_ctl(ctl)
	ap_ctl_t *ctl;
	{
	aproxy_t *a;
	int error;

	a = appr_lookup(ctl->apc_p, ctl->apc_label);
	if (a == NULL)
	error = ESRCH;
	else if (a->apr_ctl == NULL)
	error = ENXIO;
	else
	error = (*a->apr_ctl)(a, ctl);
	return error;
	}


	/*
	* Delete a proxy that has been added dynamically from those available.
	* If it is in use, return 1 (do not destroy NOW), not in use 0 or -1
	* if it cannot be matched.
	*/
	int appr_del(ap)
	aproxy_t *ap;
	{
	aproxy_t a, *app;

	for (app = &ap_proxylist; ((a = *app) != NULL); app = &a->apr_next)
	if (a == ap) {
	a->apr_flags \|= APR_DELETE;
	*app = a->apr_next;
	if (ap->apr_ref != 0)
	return 1;
	return 0;
	}
	return -1;
	}


	/*
	* Return 1 if the packet is a good match against a proxy, else 0.
	*/
	int appr_ok(fin, tcp, nat)
	fr_info_t *fin;
	tcphdr_t *tcp;
	ipnat_t *nat;
	{
	aproxy_t *apr = nat->in_apr;
	u_short dport = nat->in_dport;

	if ((apr == NULL) \|\| (apr->apr_flags & APR_DELETE) \|\|
	(fin->fin_p != apr->apr_p))
	return 0;
	if ((tcp == NULL) && dport)
	return 0;
	return 1;
	}


	int appr_ioctl(data, cmd, mode)
	caddr_t data;
	ioctlcmd_t cmd;
	int mode;
	{
	ap_ctl_t ctl;
	caddr_t ptr;
	int error;

	mode = mode; /* LINT */

	switch (cmd)
	{
	case SIOCPROXY :
	BCOPYIN(data, &ctl, sizeof(ctl));
	ptr = NULL;

	if (ctl.apc_dsize > 0) {
	KMALLOCS(ptr, caddr_t, ctl.apc_dsize);
	if (ptr == NULL)
	error = ENOMEM;
	else {
	error = copyinptr(ctl.apc_data, ptr,
	ctl.apc_dsize);
	if (error == 0)
	ctl.apc_data = ptr;
	}
	} else {
	ctl.apc_data = NULL;
	error = 0;
	}

	if (error == 0)
	error = appr_ctl(&ctl);

	if (ctl.apc_dsize > 0 && ptr != NULL && ctl.apc_data == ptr) {
	KFREES(ptr, ctl.apc_dsize);
	}
	break;

	default :
	error = EINVAL;
	}
	return error;
	}


	/*
	* If a proxy has a match function, call that to do extended packet
	* matching.
	*/
	int appr_match(fin, nat)
	fr_info_t *fin;
	nat_t *nat;
	{
	aproxy_t *apr;
	ipnat_t *ipn;

	ipn = nat->nat_ptr;
	if (ipn == NULL)
	return -1;
	apr = ipn->in_apr;
	if ((apr == NULL) \|\| (apr->apr_flags & APR_DELETE) \|\|
	(nat->nat_aps == NULL))
	return -1;
	if (apr->apr_match != NULL)
	if ((*apr->apr_match)(fin, nat->nat_aps, nat) != 0)
	return -1;
	return 0;
	}


	/*
	* Allocate a new application proxy structure and fill it in with the
	* relevant details. call the init function once complete, prior to
	* returning.
	*/
	int appr_new(fin, nat)
	fr_info_t *fin;
	nat_t *nat;
	{
	register ap_session_t *aps;
	aproxy_t *apr;

	if ((nat->nat_ptr == NULL) \|\| (nat->nat_aps != NULL))
	return -1;

	apr = nat->nat_ptr->in_apr;

	if (!apr \|\| (apr->apr_flags & APR_DELETE) \|\|
	(fin->fin_p != apr->apr_p))
	return -1;

	KMALLOC(aps, ap_session_t *);
	if (!aps)
	return -1;
	bzero((char )aps, sizeof(aps));
	aps->aps_p = fin->fin_p;
	aps->aps_data = NULL;
	aps->aps_apr = apr;
	aps->aps_psiz = 0;
	if (apr->apr_new != NULL)
	if ((*apr->apr_new)(fin, aps, nat) == -1) {
	if ((aps->aps_data != NULL) && (aps->aps_psiz != 0)) {
	KFREES(aps->aps_data, aps->aps_psiz);
	}
	KFREE(aps);
	return -1;
	}
	aps->aps_nat = nat;
	aps->aps_next = ap_sess_list;
	ap_sess_list = aps;
	nat->nat_aps = aps;

	return 0;
	}


	/*
	* Check to see if a packet should be passed through an active proxy routine
	* if one has been setup for it. We don't need to check the checksum here if
	* IPFILTER_CKSUM is defined because if it is, a failed check causes FI_BAD
	* to be set.
	*/
	int appr_check(fin, nat)
	fr_info_t *fin;
	nat_t *nat;
	{
	#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
	# if defined(ICK_VALID)
	mb_t *m;
	# endif
	int dosum = 1;
	#endif
	tcphdr_t *tcp = NULL;
	udphdr_t *udp = NULL;
	ap_session_t *aps;
	aproxy_t *apr;
	ip_t *ip;
	short rv;
	int err;
	#if !defined(_KERNEL) \|\| defined(MENTAT) \|\| defined(__sgi)
	u_32_t s1, s2, sd;
	#endif

	if (fin->fin_flx & FI_BAD)
	return -1;

	#ifndef IPFILTER_CKSUM
	if ((fin->fin_out == 0) && (fr_checkl4sum(fin) == -1)) {
	# if PROXY_DEBUG \|\| !defined(_KERNEL)
	printf("proxy l4 checksum failure\n");
	# endif
	if (fin->fin_p == IPPROTO_TCP)
	frstats[fin->fin_out].fr_tcpbad++;
	return -1;
	}
	#endif

	aps = nat->nat_aps;
	if ((aps != NULL) && (aps->aps_p == fin->fin_p)) {
	/*
	* If there is data in this packet to be proxied then try and
	* get it all into the one buffer, else drop it.
	*/
	if ((fin->fin_dlen > 0) && !(fin->fin_flx & FI_COALESCE))
	if (fr_coalesce(fin) == -1)
	return -1;
	ip = fin->fin_ip;

	switch (fin->fin_p)
	{
	case IPPROTO_TCP :
	tcp = (tcphdr_t *)fin->fin_dp;

	#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) && defined(ICK_VALID)
	m = fin->fin_qfm;
	if (dohwcksum && (m->b_ick_flag == ICK_VALID))
	dosum = 0;
	#endif
	/*
	* Don't bother the proxy with these...or in fact,
	* should we free up proxy stuff when seen?
	*/
	if ((fin->fin_tcpf & TH_RST) != 0)
	break;
	/FALLTHROUGH/
	case IPPROTO_UDP :
	udp = (udphdr_t *)fin->fin_dp;
	break;
	default :
	break;
	}

	apr = aps->aps_apr;
	err = 0;
	if (fin->fin_out != 0) {
	if (apr->apr_outpkt != NULL)
	err = (*apr->apr_outpkt)(fin, aps, nat);
	} else {
	if (apr->apr_inpkt != NULL)
	err = (*apr->apr_inpkt)(fin, aps, nat);
	}

	rv = APR_EXIT(err);
	if (rv == 1) {
	#if PROXY_DEBUG \|\| !defined(_KERNEL)
	printf("proxy says bad packet received\n");
	#endif
	return -1;
	}
	if (rv == 2) {
	#if PROXY_DEBUG \|\| !defined(_KERNEL)
	printf("proxy says free app proxy data\n");
	#endif
	appr_free(apr);
	nat->nat_aps = NULL;
	return -1;
	}

	/*
	* If err != 0 then the data size of the packet has changed
	* so we need to recalculate the header checksums for the
	* packet.
	*/
	#if !defined(_KERNEL) \|\| defined(MENTAT) \|\| defined(__sgi)
	if (err != 0) {
	short adjlen = err & 0xffff;

	s1 = LONG_SUM(ip->ip_len - adjlen);
	s2 = LONG_SUM(ip->ip_len);
	CALC_SUMD(s1, s2, sd);
	fix_outcksum(fin, &ip->ip_sum, sd);
	}
	#endif

	/*
	* For TCP packets, we may need to adjust the sequence and
	* acknowledgement numbers to reflect changes in size of the
	* data stream.
	*
	* For both TCP and UDP, recalculate the layer 4 checksum,
	* regardless, as we can't tell (here) if data has been
	* changed or not.
	*/
	if (tcp != NULL) {
	err = appr_fixseqack(fin, ip, aps, APR_INC(err));
	#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
	if (dosum)
	tcp->th_sum = fr_cksum(fin->fin_qfm, ip,
	IPPROTO_TCP, tcp);
	#else
	tcp->th_sum = fr_cksum(fin->fin_m, ip,
	IPPROTO_TCP, tcp);
	#endif
	} else if ((udp != NULL) && (udp->uh_sum != 0)) {
	#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
	if (dosum)
	udp->uh_sum = fr_cksum(fin->fin_qfm, ip,
	IPPROTO_UDP, udp);
	#else
	udp->uh_sum = fr_cksum(fin->fin_m, ip,
	IPPROTO_UDP, udp);
	#endif
	}
	aps->aps_bytes += fin->fin_plen;
	aps->aps_pkts++;
	return 1;
	}
	return 0;
	}


	/*
	* Search for an proxy by the protocol it is being used with and its name.
	*/
	aproxy_t *appr_lookup(pr, name)
	u_int pr;
	char *name;
	{
	aproxy_t *ap;

	for (ap = ap_proxies; ap->apr_p; ap++)
	if ((ap->apr_p == pr) &&
	!strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
	ap->apr_ref++;
	return ap;
	}

	for (ap = ap_proxylist; ap; ap = ap->apr_next)
	if ((ap->apr_p == pr) &&
	!strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
	ap->apr_ref++;
	return ap;
	}
	return NULL;
	}


	void appr_free(ap)
	aproxy_t *ap;
	{
	ap->apr_ref--;
	}


	void aps_free(aps)
	ap_session_t *aps;
	{
	ap_session_t a, *ap;
	aproxy_t *apr;

	if (!aps)
	return;

	for (ap = &ap_sess_list; ((a = *ap) != NULL); ap = &a->aps_next)
	if (a == aps) {
	*ap = a->aps_next;
	break;
	}

	apr = aps->aps_apr;
	if ((apr != NULL) && (apr->apr_del != NULL))
	(*apr->apr_del)(aps);

	if ((aps->aps_data != NULL) && (aps->aps_psiz != 0))
	KFREES(aps->aps_data, aps->aps_psiz);
	KFREE(aps);
	}


	/*
	* returns 2 if ack or seq number in TCP header is changed, returns 0 otherwise
	*/
	static int appr_fixseqack(fin, ip, aps, inc)
	fr_info_t *fin;
	ip_t *ip;
	ap_session_t *aps;
	int inc;
	{
	int sel, ch = 0, out, nlen;
	u_32_t seq1, seq2;
	tcphdr_t *tcp;
	short inc2;

	tcp = (tcphdr_t *)fin->fin_dp;
	out = fin->fin_out;
	/*
	* ip_len has already been adjusted by 'inc'.
	*/
	nlen = ip->ip_len;
	nlen -= (IP_HL(ip) << 2) + (TCP_OFF(tcp) << 2);

	inc2 = inc;
	inc = (int)inc2;

	if (out != 0) {
	seq1 = (u_32_t)ntohl(tcp->th_seq);
	sel = aps->aps_sel[out];

	/* switch to other set ? */
	if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
	(seq1 > aps->aps_seqmin[!sel])) {
	#if PROXY_DEBUG
	printf("proxy out switch set seq %d -> %d %x > %x\n",
	sel, !sel, seq1, aps->aps_seqmin[!sel]);
	#endif
	sel = aps->aps_sel[out] = !sel;
	}

	if (aps->aps_seqoff[sel]) {
	seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel];
	if (seq1 > seq2) {
	seq2 = aps->aps_seqoff[sel];
	seq1 += seq2;
	tcp->th_seq = htonl(seq1);
	ch = 1;
	}
	}

	if (inc && (seq1 > aps->aps_seqmin[!sel])) {
	aps->aps_seqmin[sel] = seq1 + nlen - 1;
	aps->aps_seqoff[sel] = aps->aps_seqoff[sel] + inc;
	#if PROXY_DEBUG
	printf("proxy seq set %d at %x to %d + %d\n", sel,
	aps->aps_seqmin[sel], aps->aps_seqoff[sel],
	inc);
	#endif
	}

	/***/

	seq1 = ntohl(tcp->th_ack);
	sel = aps->aps_sel[1 - out];

	/* switch to other set ? */
	if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
	(seq1 > aps->aps_ackmin[!sel])) {
	#if PROXY_DEBUG
	printf("proxy out switch set ack %d -> %d %x > %x\n",
	sel, !sel, seq1, aps->aps_ackmin[!sel]);
	#endif
	sel = aps->aps_sel[1 - out] = !sel;
	}

	if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) {
	seq2 = aps->aps_ackoff[sel];
	tcp->th_ack = htonl(seq1 - seq2);
	ch = 1;
	}
	} else {
	seq1 = ntohl(tcp->th_seq);
	sel = aps->aps_sel[out];

	/* switch to other set ? */
	if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
	(seq1 > aps->aps_ackmin[!sel])) {
	#if PROXY_DEBUG
	printf("proxy in switch set ack %d -> %d %x > %x\n",
	sel, !sel, seq1, aps->aps_ackmin[!sel]);
	#endif
	sel = aps->aps_sel[out] = !sel;
	}

	if (aps->aps_ackoff[sel]) {
	seq2 = aps->aps_ackmin[sel] - aps->aps_ackoff[sel];
	if (seq1 > seq2) {
	seq2 = aps->aps_ackoff[sel];
	seq1 += seq2;
	tcp->th_seq = htonl(seq1);
	ch = 1;
	}
	}

	if (inc && (seq1 > aps->aps_ackmin[!sel])) {
	aps->aps_ackmin[!sel] = seq1 + nlen - 1;
	aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc;
	#if PROXY_DEBUG
	printf("proxy ack set %d at %x to %d + %d\n", !sel,
	aps->aps_seqmin[!sel], aps->aps_seqoff[sel],
	inc);
	#endif
	}

	/***/

	seq1 = ntohl(tcp->th_ack);
	sel = aps->aps_sel[1 - out];

	/* switch to other set ? */
	if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
	(seq1 > aps->aps_seqmin[!sel])) {
	#if PROXY_DEBUG
	printf("proxy in switch set seq %d -> %d %x > %x\n",
	sel, !sel, seq1, aps->aps_seqmin[!sel]);
	#endif
	sel = aps->aps_sel[1 - out] = !sel;
	}

	if (aps->aps_seqoff[sel] != 0) {
	#if PROXY_DEBUG
	printf("sel %d seqoff %d seq1 %x seqmin %x\n", sel,
	aps->aps_seqoff[sel], seq1,
	aps->aps_seqmin[sel]);
	#endif
	if (seq1 > aps->aps_seqmin[sel]) {
	seq2 = aps->aps_seqoff[sel];
	tcp->th_ack = htonl(seq1 - seq2);
	ch = 1;
	}
	}
	}
	#if PROXY_DEBUG
	printf("appr_fixseqack: seq %lx ack %lx\n", ntohl(tcp->th_seq),
	ntohl(tcp->th_ack));
	#endif
	return ch ? 2 : 0;
	}


	/*
	* Initialise hook for kernel application proxies.
	* Call the initialise routine for all the compiled in kernel proxies.
	*/
	int appr_init()
	{
	aproxy_t *ap;
	int err = 0;

	for (ap = ap_proxies; ap->apr_p; ap++) {
	if (ap->apr_init != NULL) {
	err = (*ap->apr_init)();
	if (err != 0)
	break;
	}
	}
	return err;
	}


	/*
	* Unload hook for kernel application proxies.
	* Call the finialise routine for all the compiled in kernel proxies.
	*/
	void appr_unload()
	{
	aproxy_t *ap;

	for (ap = ap_proxies; ap->apr_p; ap++)
	if (ap->apr_fini != NULL)
	(*ap->apr_fini)();
	for (ap = ap_proxylist; ap; ap = ap->apr_next)
	if (ap->apr_fini != NULL)
	(*ap->apr_fini)();
	}