ip_fil_sunos4.c - net/ipfilter - Rivoreo Source Code Repositories

 /*
  * Copyright (C) 2012 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>
 #include <sys/errno.h>
 #include <sys/types.h>
 #include <sys/file.h>
 #include <sys/ioctl.h>
 #include <sys/time.h>
 #include <sys/systm.h>
 #include <sys/dir.h>
 #include <sys/mbuf.h>
 #include <sys/protosw.h>
 #include <sys/socket.h>

 #include <net/if.h>
 #include <net/af.h>
 #include <net/route.h>
 #include <netinet/in.h>
 #include <netinet/in_var.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
 #include <netinet/ip_var.h>
 #include <netinet/tcp.h>
 #include <netinet/tcp_timer.h>
 #include <netinet/udp.h>
 #include <netinet/tcpip.h>
 #include <netinet/ip_icmp.h>
 #include "netinet/ip_compat.h"
 #include "netinet/ip_fil.h"
 #include "netinet/ip_nat.h"
 #include "netinet/ip_frag.h"
 #include "netinet/ip_state.h"
 #include "netinet/ip_proxy.h"
 #include "netinet/ip_auth.h"
 #include "netinet/ip_sync.h"
 #ifdef	IPFILTER_SCAN
 #include "netinet/ip_scan.h"
 #endif
 #include "netinet/ip_pool.h"
 #include "md5.h"
 #include <sys/kernel.h>
 extern	int	ip_optcopy __P((struct ip *, struct ip *));

 #if !defined(lint)
 static const char sccsid[] = "@(#)ip_fil.c	2.41 6/5/96 (C) 1993-2000 Darren Reed";
 static const char rcsid[] = "@(#)$Id$";
 #endif

 extern	struct	protosw	inetsw[];
 extern	int	ip_forwarding;

 static	u_short	ipid = 0;
 static	int	(*ipf_savep) __P((ip_t *, int, void *, int, struct mbuf **));
 static	int	ipf_send_ip __P((fr_info_t *, mb_t *));


 #if defined(IPFILTER_LKM)
 int
 iplidentify(s)
 	char *s;
 {
 	if (strcmp(s, "ipl") == 0)
 		return 1;
 	return 0;
 }
 #endif /* IPFILTER_LKM */


 int
 ipfattach()
 {
 	int s;

 	SPL_NET(s);
 	if ((ipf_running > 0) || (ipf_checkp == ipf_check)) {
 		printf("IP Filter: already initialized\n");
 		SPL_X(s);
 		return EBUSY;
 	}

 	if (ipf_initialise() < 0) {
 		SPL_X(s);
 		return EIO;
 	}

 	bzero((char *)ipfcache, sizeof(ipfcache));
 	ipf_savep = ipf_checkp;
 	ipf_checkp = ipf_check;

 	if (ipf_control_forwarding & 1)
 		ip_forwarding = 1;

 	ipid = 0;

 	SPL_X(s);
 	timeout(ipf_slowtimer, &ipfmain, (hz / IPF_HZ_DIVIDE) * IPF_HZ_MULT);
 	return 0;
 }


 static void
 ipf_timer_func(ptr)
 	void *ptr;
 {
 	ipf_main_softc_t *softc = ptr;
 	int s;

 	SPL_NET(s);

 	if (softc->ipf_running > 0)
 		ipf_slowtimer(softc);

 	if (softc->ipf_running == -1 || softc->ipf_running == 1)
 		timeout(ipf_timer_func, &ipfmain,
 			(hz / IPF_HZ_DIVIDE) * IPF_HZ_MULT);

 	SPL_X(s);
 }


 /*
  * Disable the filter by removing the hooks from the IP input/output
  * stream.
  */
 int
 ipfdetach()
 {
 	int s;

 	SPL_NET(s);

 	untimeout(ipf_slowtimer, &ipfmain);

 	if (ipf_control_forwarding & 2)
 		ip_forwarding = 0;

 	ipf_deinitialise();

 	if (ipf_savep != NULL)
 		ipf_checkp = ipf_savep;
 	ipf_savep = NULL;

 	(void) ipf_flush(IPL_LOGIPF, FR_INQUE|FR_OUTQUE|FR_INACTIVE);
 	(void) ipf_flush(IPL_LOGIPF, FR_INQUE|FR_OUTQUE);

 	SPL_X(s);

 	return 0;
 }


 /*
  * Filter ioctl interface.
  */
 int
 ipfioctl(dev, cmd, data, mode)
 	dev_t dev;
 	int cmd;
 	caddr_t data;
 	int mode;
 {
 	int error = 0, unit = 0;
 	SPL_INT(s);

 	unit = GET_MINOR(dev);
 	if ((IPL_LOGMAX < unit) || (unit < 0)) {
 		ipfmain.ipf_interror = 130002;
 		return ENXIO;
 	}

 	if (ipf_running <= 0) {
 		if (unit != IPL_LOGIPF && cmd != SIOCIPFINTERROR) {
 			ipfmain.ipf_interror = 130003;
 			return EIO;
 		}
 		if (cmd != SIOCIPFGETNEXT && cmd != SIOCIPFGET &&
 		    cmd != SIOCIPFSET && cmd != SIOCFRENB &&
 		    cmd != SIOCGETFS && cmd != SIOCGETFF &&
 		    cmd != SIOCIPFINTERROR) {
 			ipfmain.ipf_interror = 130004;
 			return EIO;
 		}
 	}

 	SPL_NET(s);

 	error = ipf_ioctlswitch(unit, data, cmd, mode, curproc->p_uid, curproc);
 	if (error != -1) {
 		SPL_X(s);
 		return error;
 	}

 	SPL_X(s);
 	return error;
 }


 /*
  * ipf_send_reset - this could conceivably be a call to tcp_respond(), but that
  * requires a large amount of setting up and isn't any more efficient.
  */
 int
 ipf_send_reset(fin)
 	fr_info_t *fin;
 {
 	struct tcphdr *tcp, *tcp2;
 	int tlen = 0, hlen;
 	struct mbuf *m;
 	ip_t *ip;

 	tcp = fin->fin_dp;
 	if (tcp->th_flags & TH_RST)
 		return -1;		/* feedback loop */

 	if (ipf_checkl4sum(fin) == -1)
 		return -1;

 	tlen = fin->fin_dlen - (TCP_OFF(tcp) << 2) +
 		((tcp->th_flags & TH_SYN) ? 1 : 0) +
 		((tcp->th_flags & TH_FIN) ? 1 : 0);

 	MGET(m, M_DONTWAIT, MT_HEADER);
 	if (m == NULL)
 		return -1;

 	hlen = sizeof(ip_t);
 	m->m_len = sizeof(*tcp2) + hlen;
 	ip = mtod(m, struct ip *);
 	bzero((char *)ip, hlen);

 	tcp2 = (struct tcphdr *)((char *)ip + hlen);
 	tcp2->th_sport = tcp->th_dport;
 	tcp2->th_dport = tcp->th_sport;

 	if (tcp->th_flags & TH_ACK) {
 		tcp2->th_seq = tcp->th_ack;
 		tcp2->th_flags = TH_RST;
 		tcp2->th_ack = 0;
 	} else {
 		tcp2->th_seq = 0;
 		tcp2->th_ack = ntohl(tcp->th_seq);
 		tcp2->th_ack += tlen;
 		tcp2->th_ack = htonl(tcp2->th_ack);
 		tcp2->th_flags = TH_RST|TH_ACK;
 	}
 	tcp2->th_off = sizeof(*tcp2) >> 2;;
 	tcp2->th_x2 = 0;
 	tcp2->th_win = tcp->th_win;
 	tcp2->th_sum = 0;
 	tcp2->th_urp = 0;

 	ip->ip_p = IPPROTO_TCP;
 	ip->ip_len = htons(sizeof(struct tcphdr));
 	ip->ip_src.s_addr = fin->fin_daddr;
 	ip->ip_dst.s_addr = fin->fin_saddr;
 	tcp2->th_sum = in_cksum(m, hlen + sizeof(*tcp2));
 	ip->ip_len = hlen + sizeof(*tcp2);
 	return ipf_send_ip(fin, m);
 }


 static int
 ipf_send_ip(fin, m)
 	fr_info_t *fin;
 	mb_t *m;
 {
 	fr_info_t fnew;
 	ip_t *ip, *oip;
 	int hlen;

 	ip = mtod(m, ip_t *);
 	bzero((char *)&fnew, sizeof(fnew));
 	fnew.fin_main_soft = fin->fin_main_soft;

 	IP_V_A(ip, fin->fin_v);
 	switch (fin->fin_v)
 	{
 	case 4 :
 		hlen = sizeof(*oip);
 		oip = fin->fin_ip;
 		fnew.fin_v = 4;
 		fnew.fin_p = ip->ip_p;
 		fnew.fin_plen = ntohs(ip->ip_len) + hlen;
 		IP_HL_A(ip, sizeof(*oip) >> 2);
 		ip->ip_tos = oip->ip_tos;
 		ip->ip_id = fin->fin_ip->ip_id;
 		ip->ip_off = 0;
 		ip->ip_ttl = tcp_ttl;
 		ip->ip_sum = 0;
 		break;
 	default :
 		return EINVAL;
 	}

 	fnew.fin_ifp = fin->fin_ifp;
 	fnew.fin_flx = FI_NOCKSUM;
 	fnew.fin_m = m;
 	fnew.fin_ip = ip;
 	fnew.fin_mp = &m;
 	fnew.fin_hlen = hlen;
 	fnew.fin_dp = (char *)ip + hlen;
 	(void) ipf_makefrip(hlen, ip, &fnew);

 	return ipf_fastroute(m, &m, &fnew, NULL);
 }


 int
 ipf_send_icmp_err(type, fin, dst)
 	int type;
 	fr_info_t *fin;
 	int dst;
 {
 	int err, hlen = 0, xtra = 0, iclen, ohlen = 0, avail, code;
 	struct in_addr dst4;
 	struct icmp *icmp;
 	struct mbuf *m;
 	i6addr_t dst6;
 	void *ifp;
 	ip_t *ip, *ip2;

 	if ((type < 0) || (type > ICMP_MAXTYPE))
 		return -1;

 	if (ipf_checkl4sum(fin) == -1)
 		return -1;
 	MGET(m, M_DONTWAIT, MT_HEADER);
 	if (m == NULL)
 		return -1;
 	avail = MLEN;

 	code = fin->fin_icode;

 	ifp = fin->fin_ifp;
 	if (fin->fin_v == 4) {
 		if ((fin->fin_p == IPPROTO_ICMP) && !(fin->fin_flx & FI_SHORT))
 			switch (ntohs(fin->fin_data[0]) >> 8)
 			{
 			case ICMP_ECHO :
 			case ICMP_TSTAMP :
 			case ICMP_IREQ :
 			case ICMP_MASKREQ :
 				break;
 			default :
 				FREE_MB_T(m);
 				return 0;
 			}

 		if (dst == 0) {
 			if (ipf_ifpaddr(&ipfmain, 4, FRI_NORMAL, ifp,
 					&dst6, NULL) == -1) {
 				FREE_MB_T(m);
 				return -1;
 			}
 			dst4 = dst6.in4;
 		} else
 			dst4.s_addr = fin->fin_daddr;

 		hlen = sizeof(ip_t);
 		ohlen = fin->fin_hlen;
 		if (fin->fin_hlen < fin->fin_plen)
 			xtra = MIN(fin->fin_dlen, 8);
 		else
 			xtra = 0;
 	} else {
 		FREE_MB_T(m);
 		return -1;
 	}

 	iclen = hlen + sizeof(*icmp) + xtra;
 	avail -= (m->m_off + iclen);
 	if (xtra > avail)
 		xtra = avail;
 	iclen += xtra;
 	if (avail < 0) {
 		FREE_MB_T(m);
 		return -1;
 	}
 	m->m_len = iclen;
 	ip = mtod(m, ip_t *);
 	icmp = (struct icmp *)((char *)ip + hlen);
 	ip2 = (ip_t *)&icmp->icmp_ip;
 	bzero((char *)ip, iclen);

 	icmp->icmp_type = type;
 	icmp->icmp_code = fin->fin_icode;
 	icmp->icmp_cksum = 0;
 #ifdef icmp_nextmtu
 	if (type == ICMP_UNREACH && fin->fin_icode == ICMP_UNREACH_NEEDFRAG) {
 		if (fin->fin_mtu != 0) {
 			icmp->icmp_nextmtu = htons(fin->fin_mtu);

 		} else if (ifp != NULL) {
 			icmp->icmp_nextmtu = htons(GETIFMTU_4(ifp));

 		} else {	/* make up a number... */
 			icmp->icmp_nextmtu = htons(fin->fin_plen - 20);
 		}
 	}
 #endif

 	bcopy((char *)fin->fin_ip, (char *)ip2, ohlen);

 	ip2->ip_len = htons(ip2->ip_len);
 	ip2->ip_off = htons(ip2->ip_off);

 	ip->ip_p = IPPROTO_ICMP;
 	ip->ip_src.s_addr = dst4.s_addr;
 	ip->ip_dst.s_addr = fin->fin_saddr;

 	if (xtra > 0)
 		bcopy((char *)fin->fin_ip + fin->fin_hlen,
 		      (char *)&icmp->icmp_ip + fin->fin_hlen, xtra);
 	icmp->icmp_cksum = ipf_cksum((u_short *)icmp, sizeof(*icmp) + 8);
 	ip->ip_len = iclen;
 	ip->ip_p = IPPROTO_ICMP;
 	err = ipf_send_ip(fin, m);
 	return err;
 }


 #if !defined(IPFILTER_LKM)
 int iplinit __P((void));

 int
 iplinit()
 {
 	if (ipfattach() != 0)
 		printf("IP Filter failed to attach\n");
 	ip_init();
 }
 #endif


 size_t
 mbufchainlen(m0)
 	register struct mbuf *m0;
 {
 	register size_t len = 0;

 	for (; m0; m0 = m0->m_next)
 		len += m0->m_len;
 	return len;
 }


 /*
  * m0 - pointer to mbuf where the IP packet starts
  * mpp - pointer to the mbuf pointer that is the start of the mbuf chain
  */
 int
 ipf_fastroute(m0, mpp, fin, fdp)
 	struct mbuf *m0, **mpp;
 	fr_info_t *fin;
 	frdest_t *fdp;
 {
 	register struct ip *ip, *mhip;
 	register struct mbuf *m = *mpp;
 	register struct route *ro;
 	int len, off, error = 0, hlen, code;
 	struct ifnet *ifp, *sifp;
 	struct sockaddr_in *dst;
 	struct route iproute;
 	u_short ip_off;
 	frdest_t node;
 	frentry_t *fr;

 	hlen = fin->fin_hlen;
 	ip = mtod(m0, struct ip *);

 	/*
 	 * Route packet.
 	 */
 	ro = &iproute;
 	bzero((caddr_t)ro, sizeof (*ro));
 	dst = (struct sockaddr_in *)&ro->ro_dst;
 	dst->sin_family = AF_INET;
 	dst->sin_addr = ip->ip_dst;

 	fr = fin->fin_fr;
 	if ((fr != NULL) && !(fr->fr_flags & FR_KEEPSTATE) && (fdp != NULL) &&
 	    (fdp->fd_type == FRD_DSTLIST)) {
 		if (ipf_dstlist_select_node(fin, fdp->fd_ptr, NULL, &node) == 0)
 			fdp = &node;
 	}
 	if (fdp != NULL)
 		ifp = fdp->fd_ptr;
 	else
 		ifp = fin->fin_ifp;

 	if ((fdp != NULL) && (fdp->fd_ip.s_addr != 0))
 		dst->sin_addr = fdp->fd_ip;

 	rtalloc(ro);
 	if (ifp == NULL) {
 		if (!fr || !(fr->fr_flags & FR_FASTROUTE)) {
 			error = -2;
 			goto bad;
 		}
 		if (ro->ro_rt == 0 || (ifp = ro->ro_rt->rt_ifp) == 0) {
 			if (in_localaddr(ip->ip_dst))
 				error = EHOSTUNREACH;
 			else
 				error = ENETUNREACH;
 			goto bad;
 		}
 		if (ro->ro_rt->rt_flags & RTF_GATEWAY)
 			dst = (struct sockaddr_in *)&ro->ro_rt->rt_gateway;
 	}
 	if (ro->ro_rt != NULL)
 		ro->ro_rt->rt_use++;

 	/*
 	 * For input packets which are being "fastrouted", they won't
 	 * go back through output filtering and miss their chance to get
 	 * NAT'd and counted.  Duplicated packets aren't considered to be
 	 * part of the normal packet stream, so do not NAT them or pass
 	 * them through stateful checking, etc.
 	 */
 	if ((fdp != &fr->fr_dif) && (fin->fin_out == 0)) {
 		sifp = fin->fin_ifp;
 		fin->fin_ifp = ifp;
 		fin->fin_out = 1;
 		(void) ipf_acctpkt(fin, NULL);
 		fin->fin_fr = NULL;
 		if (!fr || !(fr->fr_flags & FR_RETMASK)) {
 			u_32_t pass;

 			(void) ipf_state_check(fin, &pass);
 		}

 		switch (ipf_nat_checkout(fin, NULL))
 		{
 		case 0 :
 			break;
 		case 1 :
 			break;
 		case -1 :
 			error = -1;
 			goto bad;
 			break;
 		}

 		fin->fin_ifp = sifp;
 		fin->fin_out = 0;
 	} else
 		ip->ip_sum = 0;
 	/*
 	 * If small enough for interface, can just send directly.
 	 */
 	if (ip->ip_len <= ifp->if_mtu) {
 		ip->ip_len = htons(ip->ip_len);
 		ip->ip_off = htons(ip->ip_off);
 		if (!ip->ip_sum)
 			ip->ip_sum = in_cksum(m, hlen);
 		error = (*ifp->if_output)(ifp, m, (struct sockaddr *)dst);
 		goto done;
 	}
 	/*
 	 * Too large for interface; fragment if possible.
 	 * Must be able to put at least 8 bytes per fragment.
 	 */
 	ip_off = ip->ip_off;
 	if (ip_off & IP_DF) {
 		error = EMSGSIZE;
 		goto bad;
 	}
 	len = (ifp->if_mtu - hlen) &~ 7;
 	if (len < 8) {
 		error = EMSGSIZE;
 		goto bad;
 	}

     {
 	int mhlen, firstlen = len;
 	struct mbuf **mnext = &m->m_act;

 	/*
 	 * Loop through length of segment after first fragment,
 	 * make new header and copy data of each part and link onto chain.
 	 */
 	m0 = m;
 	mhlen = sizeof (struct ip);
 	for (off = hlen + len; off < ip->ip_len; off += len) {
 		MGET(m, M_DONTWAIT, MT_HEADER);
 		if (m == 0) {
 			m = m0;
 			error = ENOBUFS;
 			goto bad;
 		}
 		m->m_off = MMAXOFF - hlen;
 		mhip = mtod(m, struct ip *);
 		bcopy((char *)ip, (char *)mhip, sizeof(*ip));
 		if (hlen > sizeof (struct ip)) {
 			mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
 			IP_HL_A(mhip, mhlen >> 2);
 		}
 		m->m_len = mhlen;
 		mhip->ip_off = ((off - hlen) >> 3) + ip_off;
 		if (off + len >= ip->ip_len)
 			len = ip->ip_len - off;
 		else
 			mhip->ip_off |= IP_MF;
 		mhip->ip_len = htons((u_short)(len + mhlen));
 		m->m_next = m_copy(m0, off, len);
 		if (m->m_next == 0) {
 			error = ENOBUFS;	/* ??? */
 			goto sendorfree;
 		}
 		mhip->ip_off = htons((u_short)mhip->ip_off);
 		mhip->ip_sum = 0;
 		mhip->ip_sum = in_cksum(m, mhlen);
 		*mnext = m;
 		mnext = &m->m_act;
 	}
 	/*
 	 * Update first fragment by trimming what's been copied out
 	 * and updating header, then send each fragment (in order).
 	 */
 	m_adj(m0, hlen + firstlen - ip->ip_len);
 	ip->ip_len = htons((u_short)(hlen + firstlen));
 	ip->ip_off = htons((u_short)IP_MF);
 	ip->ip_sum = 0;
 	ip->ip_sum = in_cksum(m0, hlen);
 sendorfree:
 	for (m = m0; m; m = m0) {
 		m0 = m->m_act;
 		m->m_act = 0;
 		if (error == 0)
 			error = (*ifp->if_output)(ifp, m,
 			    (struct sockaddr *)dst);
 		else
 			FREE_MB_T(m);
 	}
     }
 done:
 	if (!error)
 		ipf_frouteok[0]++;
 	else
 		ipf_frouteok[1]++;

 	if (ro->ro_rt != NULL) {
 		RTFREE(ro->ro_rt);
 	}
 	return 0;
 bad:
 	if (error == EMSGSIZE) {
 		sifp = fin->fin_ifp;
 		code = fin->fin_icode;
 		fin->fin_icode = ICMP_UNREACH_NEEDFRAG;
 		fin->fin_ifp = ifp;
 		(void) ipf_send_icmp_err(ICMP_UNREACH, fin, 1);
 		fin->fin_ifp = sifp;
 		fin->fin_icode = code;
 	}
 	FREE_MB_T(m);
 	goto done;
 }


 int
 ipf_verifysrc(fin)
 	fr_info_t *fin;
 {
 	struct sockaddr_in *dst;
 	struct route iproute;
 	void *rtifp;

 	bzero((char *)&iproute, sizeof(iproute));
 	dst = (struct sockaddr_in *)&iproute.ro_dst;
 	dst->sin_family = AF_INET;
 	dst->sin_addr.s_addr = fin->fin_saddr;
 	rtalloc(&iproute);
 	if (iproute.ro_rt == NULL)
 		return 0;
 	rtifp = iproute.ro_rt->rt_ifp;
 	RTFREE(iproute.ro_rt);
 	return (fin->fin_ifp == rtifp);
 }


 /*
  * return the first IP Address associated with an interface
  */
 int
 ipf_ifpaddr(softc, v, atype, ifptr, inp, inpmask)
 	ipf_main_softc_t *softc;
 	int v, atype;
 	void *ifptr;
 	i6addr_t *inp, *inpmask;
 {
 	struct sockaddr_in *sin, *mask;
 	struct in_ifaddr *ia;
 	struct ifnet *ifp;

 	if ((ifptr == NULL) || (ifptr == (void *)-1))
 		return -1;

 	ifp = ifptr;
 	if (ifp == NULL)
 		return -1;

 	for (ia = in_ifaddr; ia != NULL; ia = ia->ia_next)
 		if (ia->ia_ifp == ifp) {
 			sin = (struct sockaddr_in *)&ia->ia_addr;
 			break;
 		}

 	if (ia == NULL)
 		return -1;

 	if (atype == FRI_BROADCAST)
 		sin = (struct sockaddr_in *)&ia->ia_broadaddr;
 	else if (atype == FRI_PEERADDR)
 		sin = (struct sockaddr_in *)&ia->ia_dstaddr;
 	mask = (struct sockaddr_in *)&ia->ia_subnetmask;

 	return ipf_ifpfillv4addr(atype, sin, mask, &inp->in4, &inpmask->in4);
 }


 u_32_t
 ipf_newisn(fin)
 	fr_info_t *fin;
 {
 	static iss_seq_off = 0;
 	u_char hash[16];
 	u_32_t newiss;
 	MD5_CTX ctx;

 	/*
 	 * Compute the base value of the ISS.  It is a hash
 	 * of (saddr, sport, daddr, dport, secret).
 	 */
 	MD5Init(&ctx);

 	MD5Update(&ctx, (u_char *) &fin->fin_fi.fi_src,
 		  sizeof(fin->fin_fi.fi_src));
 	MD5Update(&ctx, (u_char *) &fin->fin_fi.fi_dst,
 		  sizeof(fin->fin_fi.fi_dst));
 	MD5Update(&ctx, (u_char *) &fin->fin_dat, sizeof(fin->fin_dat));

 	MD5Update(&ctx, ipf_iss_secret, sizeof(ipf_iss_secret));

 	MD5Final(hash, &ctx);

 	memcpy(&newiss, hash, sizeof(newiss));

 	/*
 	 * Now increment our "timer", and add it in to
 	 * the computed value.
 	 *
 	 * XXX Use `addin'?
 	 * XXX TCP_ISSINCR too large to use?
 	 */
 	iss_seq_off += 0x00010000;
 	newiss += iss_seq_off;
 	return newiss;
 }


 /* ------------------------------------------------------------------------ */
 /* Function:    ipf_nextipid                                                */
 /* Returns:     int - 0 == success, -1 == error (packet should be droppped) */
 /* Parameters:  fin(I) - pointer to packet information                      */
 /*                                                                          */
 /* Returns the next IPv4 ID to use for this packet.                         */
 /* ------------------------------------------------------------------------ */
 INLINE u_short
 ipf_nextipid(fin)
 	fr_info_t *fin;
 {
 	u_short id;

 	id = ipid++;

 	return id;
 }


 INLINE int
 ipf_checkv4sum(fin)
 	fr_info_t *fin;
 {
 	if ((fin->fin_flx & FI_NOCKSUM) != 0)
 		return 0;

 	if ((fin->fin_flx & FI_SHORT) != 0)
 		return 1;

 	if (fin->fin_cksum != FI_CK_NEEDED)
 		return (fin->fin_cksum > FI_CK_NEEDED) ? 0 : -1;

 	if (ipf_checkl4sum(fin) == -1) {
 		fin->fin_flx |= FI_BAD;
 		return -1;
 	}
 	return 0;
 }


 /* ------------------------------------------------------------------------ */
 /* Function:    ipf_pullup                                                  */
 /* Returns:     NULL == pullup failed, else pointer to protocol header      */
 /* Parameters:  xmin(I)- pointer to buffer where data packet starts         */
 /*              fin(I) - pointer to packet information                      */
 /*              len(I) - number of bytes to pullup                          */
 /*                                                                          */
 /* Attempt to move at least len bytes (from the start of the buffer) into a */
 /* single buffer for ease of access.  Operating system native functions are */
 /* used to manage buffers - if necessary.  If the entire packet ends up in  */
 /* a single buffer, set the FI_COALESCE flag even though ipf_coalesce() has */
 /* not been called.  Both fin_ip and fin_dp are updated before exiting _IF_ */
 /* and ONLY if the pullup succeeds.                                         */
 /*                                                                          */
 /* We assume that 'xmin' is a pointer to a buffer that is part of the chain */
 /* of buffers that starts at *fin->fin_mp.                                  */
 /* ------------------------------------------------------------------------ */
 void *
 ipf_pullup(xmin, fin, len)
 	mb_t *xmin;
 	fr_info_t *fin;
 	int len;
 {
 	int out = fin->fin_out, dpoff, ipoff;
 	mb_t *m = xmin;
 	char *ip;

 	if (m == NULL)
 		return NULL;

 	ip = (char *)fin->fin_ip;
 	if ((fin->fin_flx & FI_COALESCE) != 0)
 		return ip;

 	ipoff = fin->fin_ipoff;
 	if (fin->fin_dp != NULL)
 		dpoff = (char *)fin->fin_dp - (char *)ip;
 	else
 		dpoff = 0;

 	if (M_LEN(m) < len) {
 		mb_t *n = *fin->fin_mp;

 		if (m != n) {
 			for (; n->m_next != m; n = n->m_next)
 				;
 		} else {
 			n = NULL;
 		}

 		if (len > MLEN) {
 			FREE_MB_T(*fin->fin_mp);
 			m = NULL;
 			n = NULL;
 		} else {
 			m = m_pullup(m, len);
 		}

 		if (n != NULL)
 			n->m_next = m;

 		if (m == NULL) {
 			if (n != NULL) {
 				FREE_MB_T(*fin->fin_mp);
 			}
 			*fin->fin_mp = NULL;
 			fin->fin_m = NULL;
 			return NULL;
 		}

 		if (n == NULL)
 			*fin->fin_mp = m;

 		while (M_LEN(m) == 0) {
 			m = m->m_next;
 		}

 		fin->fin_m = m;
 		ip = MTOD(m, char *) + ipoff;

 		fin->fin_ip = (ip_t *)ip;
 		if (fin->fin_dp != NULL)
 			fin->fin_dp = (char *)fin->fin_ip + dpoff;
 	}

 	if (len == fin->fin_plen)
 		fin->fin_flx |= FI_COALESCE;
 	return ip;
 }


 int
 ipf_inject(fin, m)
 	fr_info_t *fin;
 	mb_t *m;
 {
 	int error;

 	if (fin->fin_out == 0) {
 		struct ifqueue *ifq;

 		ifq = &ipintrq;

 		if (IF_QFULL(ifq)) {
 			IF_DROP(ifq);
 			FREE_MB_T(m);
 			error = ENOBUFS;
 		} else {
 			IF_ENQUEUE(ifq, m);
 			error = 0;
 		}
 	} else {
 		error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL);
 	}

 	return error;
 }


 /*
  * In the face of no kernel random function, this is implemented...it is
  * not meant to be random, just a fill in.
  */
 int
 ipf_random()
 {
 	static int last = 0;
 	static int calls = 0;
 	struct timeval tv;
 	int number;

 	GETKTIME(&tv);
 	last *= tv.tv_usec + calls++;
 	last += (int)&range * ipf_ticks;
 	number = last + tv.tv_sec;
 	return number;
 }


 u_short
 ipf_pcksum(fin, hlen, sum)
 {
 	u_short sum2;

 	slen = fin->fin_plen - hlen;
 	m->m_off += hlen;
 	m->m_len -= hlen;
 	sum2 = in_cksum(fin->fin_m, slen);
 	m->m_len += hlen;
 	m->m_off -= hlen;
 	/*
 	 * Both sum and sum2 are partial sums, so combine them together.
 	 */
 	sum += ~sum2 & 0xffff;
 	while (sum > 0xffff)
 		sum = (sum & 0xffff) + (sum >> 16);
 	sum2 = ~sum & 0xffff;
 	return sum2;
 }
	/*
	* Copyright (C) 2012 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>
	#include <sys/errno.h>
	#include <sys/types.h>
	#include <sys/file.h>
	#include <sys/ioctl.h>
	#include <sys/time.h>
	#include <sys/systm.h>
	#include <sys/dir.h>
	#include <sys/mbuf.h>
	#include <sys/protosw.h>
	#include <sys/socket.h>

	#include <net/if.h>
	#include <net/af.h>
	#include <net/route.h>
	#include <netinet/in.h>
	#include <netinet/in_var.h>
	#include <netinet/in_systm.h>
	#include <netinet/ip.h>
	#include <netinet/ip_var.h>
	#include <netinet/tcp.h>
	#include <netinet/tcp_timer.h>
	#include <netinet/udp.h>
	#include <netinet/tcpip.h>
	#include <netinet/ip_icmp.h>
	#include "netinet/ip_compat.h"
	#include "netinet/ip_fil.h"
	#include "netinet/ip_nat.h"
	#include "netinet/ip_frag.h"
	#include "netinet/ip_state.h"
	#include "netinet/ip_proxy.h"
	#include "netinet/ip_auth.h"
	#include "netinet/ip_sync.h"
	#ifdef IPFILTER_SCAN
	#include "netinet/ip_scan.h"
	#endif
	#include "netinet/ip_pool.h"
	#include "md5.h"
	#include <sys/kernel.h>
	extern int ip_optcopy __P((struct ip , struct ip ));

	#if !defined(lint)
	static const char sccsid[] = "@(#)ip_fil.c 2.41 6/5/96 (C) 1993-2000 Darren Reed";
	static const char rcsid[] = "@(#)$Id$";
	#endif

	extern struct protosw inetsw[];
	extern int ip_forwarding;

	static u_short ipid = 0;
	static int (ipf_savep) __P((ip_t , int, void , int, struct mbuf *));
	static int ipf_send_ip __P((fr_info_t , mb_t ));


	#if defined(IPFILTER_LKM)
	int
	iplidentify(s)
	char *s;
	{
	if (strcmp(s, "ipl") == 0)
	return 1;
	return 0;
	}
	#endif /* IPFILTER_LKM */


	int
	ipfattach()
	{
	int s;

	SPL_NET(s);
	if ((ipf_running > 0) \|\| (ipf_checkp == ipf_check)) {
	printf("IP Filter: already initialized\n");
	SPL_X(s);
	return EBUSY;
	}

	if (ipf_initialise() < 0) {
	SPL_X(s);
	return EIO;
	}

	bzero((char *)ipfcache, sizeof(ipfcache));
	ipf_savep = ipf_checkp;
	ipf_checkp = ipf_check;

	if (ipf_control_forwarding & 1)
	ip_forwarding = 1;

	ipid = 0;

	SPL_X(s);
	timeout(ipf_slowtimer, &ipfmain, (hz / IPF_HZ_DIVIDE) * IPF_HZ_MULT);
	return 0;
	}


	static void
	ipf_timer_func(ptr)
	void *ptr;
	{
	ipf_main_softc_t *softc = ptr;
	int s;

	SPL_NET(s);

	if (softc->ipf_running > 0)
	ipf_slowtimer(softc);

	if (softc->ipf_running == -1 \|\| softc->ipf_running == 1)
	timeout(ipf_timer_func, &ipfmain,
	(hz / IPF_HZ_DIVIDE) * IPF_HZ_MULT);

	SPL_X(s);
	}


	/*
	* Disable the filter by removing the hooks from the IP input/output
	* stream.
	*/
	int
	ipfdetach()
	{
	int s;

	SPL_NET(s);

	untimeout(ipf_slowtimer, &ipfmain);

	if (ipf_control_forwarding & 2)
	ip_forwarding = 0;

	ipf_deinitialise();

	if (ipf_savep != NULL)
	ipf_checkp = ipf_savep;
	ipf_savep = NULL;

	(void) ipf_flush(IPL_LOGIPF, FR_INQUE\|FR_OUTQUE\|FR_INACTIVE);
	(void) ipf_flush(IPL_LOGIPF, FR_INQUE\|FR_OUTQUE);

	SPL_X(s);

	return 0;
	}


	/*
	* Filter ioctl interface.
	*/
	int
	ipfioctl(dev, cmd, data, mode)
	dev_t dev;
	int cmd;
	caddr_t data;
	int mode;
	{
	int error = 0, unit = 0;
	SPL_INT(s);

	unit = GET_MINOR(dev);
	if ((IPL_LOGMAX < unit) \|\| (unit < 0)) {
	ipfmain.ipf_interror = 130002;
	return ENXIO;
	}

	if (ipf_running <= 0) {
	if (unit != IPL_LOGIPF && cmd != SIOCIPFINTERROR) {
	ipfmain.ipf_interror = 130003;
	return EIO;
	}
	if (cmd != SIOCIPFGETNEXT && cmd != SIOCIPFGET &&
	cmd != SIOCIPFSET && cmd != SIOCFRENB &&
	cmd != SIOCGETFS && cmd != SIOCGETFF &&
	cmd != SIOCIPFINTERROR) {
	ipfmain.ipf_interror = 130004;
	return EIO;
	}
	}

	SPL_NET(s);

	error = ipf_ioctlswitch(unit, data, cmd, mode, curproc->p_uid, curproc);
	if (error != -1) {
	SPL_X(s);
	return error;
	}

	SPL_X(s);
	return error;
	}


	/*
	* ipf_send_reset - this could conceivably be a call to tcp_respond(), but that
	* requires a large amount of setting up and isn't any more efficient.
	*/
	int
	ipf_send_reset(fin)
	fr_info_t *fin;
	{
	struct tcphdr tcp, tcp2;
	int tlen = 0, hlen;
	struct mbuf *m;
	ip_t *ip;

	tcp = fin->fin_dp;
	if (tcp->th_flags & TH_RST)
	return -1; /* feedback loop */

	if (ipf_checkl4sum(fin) == -1)
	return -1;

	tlen = fin->fin_dlen - (TCP_OFF(tcp) << 2) +
	((tcp->th_flags & TH_SYN) ? 1 : 0) +
	((tcp->th_flags & TH_FIN) ? 1 : 0);

	MGET(m, M_DONTWAIT, MT_HEADER);
	if (m == NULL)
	return -1;

	hlen = sizeof(ip_t);
	m->m_len = sizeof(*tcp2) + hlen;
	ip = mtod(m, struct ip *);
	bzero((char *)ip, hlen);

	tcp2 = (struct tcphdr )((char )ip + hlen);
	tcp2->th_sport = tcp->th_dport;
	tcp2->th_dport = tcp->th_sport;

	if (tcp->th_flags & TH_ACK) {
	tcp2->th_seq = tcp->th_ack;
	tcp2->th_flags = TH_RST;
	tcp2->th_ack = 0;
	} else {
	tcp2->th_seq = 0;
	tcp2->th_ack = ntohl(tcp->th_seq);
	tcp2->th_ack += tlen;
	tcp2->th_ack = htonl(tcp2->th_ack);
	tcp2->th_flags = TH_RST\|TH_ACK;
	}
	tcp2->th_off = sizeof(*tcp2) >> 2;;
	tcp2->th_x2 = 0;
	tcp2->th_win = tcp->th_win;
	tcp2->th_sum = 0;
	tcp2->th_urp = 0;

	ip->ip_p = IPPROTO_TCP;
	ip->ip_len = htons(sizeof(struct tcphdr));
	ip->ip_src.s_addr = fin->fin_daddr;
	ip->ip_dst.s_addr = fin->fin_saddr;
	tcp2->th_sum = in_cksum(m, hlen + sizeof(*tcp2));
	ip->ip_len = hlen + sizeof(*tcp2);
	return ipf_send_ip(fin, m);
	}


	static int
	ipf_send_ip(fin, m)
	fr_info_t *fin;
	mb_t *m;
	{
	fr_info_t fnew;
	ip_t ip, oip;
	int hlen;

	ip = mtod(m, ip_t *);
	bzero((char *)&fnew, sizeof(fnew));
	fnew.fin_main_soft = fin->fin_main_soft;

	IP_V_A(ip, fin->fin_v);
	switch (fin->fin_v)
	{
	case 4 :
	hlen = sizeof(*oip);
	oip = fin->fin_ip;
	fnew.fin_v = 4;
	fnew.fin_p = ip->ip_p;
	fnew.fin_plen = ntohs(ip->ip_len) + hlen;
	IP_HL_A(ip, sizeof(*oip) >> 2);
	ip->ip_tos = oip->ip_tos;
	ip->ip_id = fin->fin_ip->ip_id;
	ip->ip_off = 0;
	ip->ip_ttl = tcp_ttl;
	ip->ip_sum = 0;
	break;
	default :
	return EINVAL;
	}

	fnew.fin_ifp = fin->fin_ifp;
	fnew.fin_flx = FI_NOCKSUM;
	fnew.fin_m = m;
	fnew.fin_ip = ip;
	fnew.fin_mp = &m;
	fnew.fin_hlen = hlen;
	fnew.fin_dp = (char *)ip + hlen;
	(void) ipf_makefrip(hlen, ip, &fnew);

	return ipf_fastroute(m, &m, &fnew, NULL);
	}


	int
	ipf_send_icmp_err(type, fin, dst)
	int type;
	fr_info_t *fin;
	int dst;
	{
	int err, hlen = 0, xtra = 0, iclen, ohlen = 0, avail, code;
	struct in_addr dst4;
	struct icmp *icmp;
	struct mbuf *m;
	i6addr_t dst6;
	void *ifp;
	ip_t ip, ip2;

	if ((type < 0) \|\| (type > ICMP_MAXTYPE))
	return -1;

	if (ipf_checkl4sum(fin) == -1)
	return -1;
	MGET(m, M_DONTWAIT, MT_HEADER);
	if (m == NULL)
	return -1;
	avail = MLEN;

	code = fin->fin_icode;

	ifp = fin->fin_ifp;
	if (fin->fin_v == 4) {
	if ((fin->fin_p == IPPROTO_ICMP) && !(fin->fin_flx & FI_SHORT))
	switch (ntohs(fin->fin_data[0]) >> 8)
	{
	case ICMP_ECHO :
	case ICMP_TSTAMP :
	case ICMP_IREQ :
	case ICMP_MASKREQ :
	break;
	default :
	FREE_MB_T(m);
	return 0;
	}

	if (dst == 0) {
	if (ipf_ifpaddr(&ipfmain, 4, FRI_NORMAL, ifp,
	&dst6, NULL) == -1) {
	FREE_MB_T(m);
	return -1;
	}
	dst4 = dst6.in4;
	} else
	dst4.s_addr = fin->fin_daddr;

	hlen = sizeof(ip_t);
	ohlen = fin->fin_hlen;
	if (fin->fin_hlen < fin->fin_plen)
	xtra = MIN(fin->fin_dlen, 8);
	else
	xtra = 0;
	} else {
	FREE_MB_T(m);
	return -1;
	}

	iclen = hlen + sizeof(*icmp) + xtra;
	avail -= (m->m_off + iclen);
	if (xtra > avail)
	xtra = avail;
	iclen += xtra;
	if (avail < 0) {
	FREE_MB_T(m);
	return -1;
	}
	m->m_len = iclen;
	ip = mtod(m, ip_t *);
	icmp = (struct icmp )((char )ip + hlen);
	ip2 = (ip_t *)&icmp->icmp_ip;
	bzero((char *)ip, iclen);

	icmp->icmp_type = type;
	icmp->icmp_code = fin->fin_icode;
	icmp->icmp_cksum = 0;
	#ifdef icmp_nextmtu
	if (type == ICMP_UNREACH && fin->fin_icode == ICMP_UNREACH_NEEDFRAG) {
	if (fin->fin_mtu != 0) {
	icmp->icmp_nextmtu = htons(fin->fin_mtu);

	} else if (ifp != NULL) {
	icmp->icmp_nextmtu = htons(GETIFMTU_4(ifp));

	} else { /* make up a number... */
	icmp->icmp_nextmtu = htons(fin->fin_plen - 20);
	}
	}
	#endif

	bcopy((char )fin->fin_ip, (char )ip2, ohlen);

	ip2->ip_len = htons(ip2->ip_len);
	ip2->ip_off = htons(ip2->ip_off);

	ip->ip_p = IPPROTO_ICMP;
	ip->ip_src.s_addr = dst4.s_addr;
	ip->ip_dst.s_addr = fin->fin_saddr;

	if (xtra > 0)
	bcopy((char *)fin->fin_ip + fin->fin_hlen,
	(char *)&icmp->icmp_ip + fin->fin_hlen, xtra);
	icmp->icmp_cksum = ipf_cksum((u_short )icmp, sizeof(icmp) + 8);
	ip->ip_len = iclen;
	ip->ip_p = IPPROTO_ICMP;
	err = ipf_send_ip(fin, m);
	return err;
	}


	#if !defined(IPFILTER_LKM)
	int iplinit __P((void));

	int
	iplinit()
	{
	if (ipfattach() != 0)
	printf("IP Filter failed to attach\n");
	ip_init();
	}
	#endif


	size_t
	mbufchainlen(m0)
	register struct mbuf *m0;
	{
	register size_t len = 0;

	for (; m0; m0 = m0->m_next)
	len += m0->m_len;
	return len;
	}


	/*
	* m0 - pointer to mbuf where the IP packet starts
	* mpp - pointer to the mbuf pointer that is the start of the mbuf chain
	*/
	int
	ipf_fastroute(m0, mpp, fin, fdp)
	struct mbuf m0, *mpp;
	fr_info_t *fin;
	frdest_t *fdp;
	{
	register struct ip ip, mhip;
	register struct mbuf m = mpp;
	register struct route *ro;
	int len, off, error = 0, hlen, code;
	struct ifnet ifp, sifp;
	struct sockaddr_in *dst;
	struct route iproute;
	u_short ip_off;
	frdest_t node;
	frentry_t *fr;

	hlen = fin->fin_hlen;
	ip = mtod(m0, struct ip *);

	/*
	* Route packet.
	*/
	ro = &iproute;
	bzero((caddr_t)ro, sizeof (*ro));
	dst = (struct sockaddr_in *)&ro->ro_dst;
	dst->sin_family = AF_INET;
	dst->sin_addr = ip->ip_dst;

	fr = fin->fin_fr;
	if ((fr != NULL) && !(fr->fr_flags & FR_KEEPSTATE) && (fdp != NULL) &&
	(fdp->fd_type == FRD_DSTLIST)) {
	if (ipf_dstlist_select_node(fin, fdp->fd_ptr, NULL, &node) == 0)
	fdp = &node;
	}
	if (fdp != NULL)
	ifp = fdp->fd_ptr;
	else
	ifp = fin->fin_ifp;

	if ((fdp != NULL) && (fdp->fd_ip.s_addr != 0))
	dst->sin_addr = fdp->fd_ip;

	rtalloc(ro);
	if (ifp == NULL) {
	if (!fr \|\| !(fr->fr_flags & FR_FASTROUTE)) {
	error = -2;
	goto bad;
	}
	if (ro->ro_rt == 0 \|\| (ifp = ro->ro_rt->rt_ifp) == 0) {
	if (in_localaddr(ip->ip_dst))
	error = EHOSTUNREACH;
	else
	error = ENETUNREACH;
	goto bad;
	}
	if (ro->ro_rt->rt_flags & RTF_GATEWAY)
	dst = (struct sockaddr_in *)&ro->ro_rt->rt_gateway;
	}
	if (ro->ro_rt != NULL)
	ro->ro_rt->rt_use++;

	/*
	* For input packets which are being "fastrouted", they won't
	* go back through output filtering and miss their chance to get
	* NAT'd and counted. Duplicated packets aren't considered to be
	* part of the normal packet stream, so do not NAT them or pass
	* them through stateful checking, etc.
	*/
	if ((fdp != &fr->fr_dif) && (fin->fin_out == 0)) {
	sifp = fin->fin_ifp;
	fin->fin_ifp = ifp;
	fin->fin_out = 1;
	(void) ipf_acctpkt(fin, NULL);
	fin->fin_fr = NULL;
	if (!fr \|\| !(fr->fr_flags & FR_RETMASK)) {
	u_32_t pass;

	(void) ipf_state_check(fin, &pass);
	}

	switch (ipf_nat_checkout(fin, NULL))
	{
	case 0 :
	break;
	case 1 :
	break;
	case -1 :
	error = -1;
	goto bad;
	break;
	}

	fin->fin_ifp = sifp;
	fin->fin_out = 0;
	} else
	ip->ip_sum = 0;
	/*
	* If small enough for interface, can just send directly.
	*/
	if (ip->ip_len <= ifp->if_mtu) {
	ip->ip_len = htons(ip->ip_len);
	ip->ip_off = htons(ip->ip_off);
	if (!ip->ip_sum)
	ip->ip_sum = in_cksum(m, hlen);
	error = (ifp->if_output)(ifp, m, (struct sockaddr )dst);
	goto done;
	}
	/*
	* Too large for interface; fragment if possible.
	* Must be able to put at least 8 bytes per fragment.
	*/
	ip_off = ip->ip_off;
	if (ip_off & IP_DF) {
	error = EMSGSIZE;
	goto bad;
	}
	len = (ifp->if_mtu - hlen) &~ 7;
	if (len < 8) {
	error = EMSGSIZE;
	goto bad;
	}

	{
	int mhlen, firstlen = len;
	struct mbuf **mnext = &m->m_act;

	/*
	* Loop through length of segment after first fragment,
	* make new header and copy data of each part and link onto chain.
	*/
	m0 = m;
	mhlen = sizeof (struct ip);
	for (off = hlen + len; off < ip->ip_len; off += len) {
	MGET(m, M_DONTWAIT, MT_HEADER);
	if (m == 0) {
	m = m0;
	error = ENOBUFS;
	goto bad;
	}
	m->m_off = MMAXOFF - hlen;
	mhip = mtod(m, struct ip *);
	bcopy((char )ip, (char )mhip, sizeof(*ip));
	if (hlen > sizeof (struct ip)) {
	mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
	IP_HL_A(mhip, mhlen >> 2);
	}
	m->m_len = mhlen;
	mhip->ip_off = ((off - hlen) >> 3) + ip_off;
	if (off + len >= ip->ip_len)
	len = ip->ip_len - off;
	else
	mhip->ip_off \|= IP_MF;
	mhip->ip_len = htons((u_short)(len + mhlen));
	m->m_next = m_copy(m0, off, len);
	if (m->m_next == 0) {
	error = ENOBUFS; /* ??? */
	goto sendorfree;
	}
	mhip->ip_off = htons((u_short)mhip->ip_off);
	mhip->ip_sum = 0;
	mhip->ip_sum = in_cksum(m, mhlen);
	*mnext = m;
	mnext = &m->m_act;
	}
	/*
	* Update first fragment by trimming what's been copied out
	* and updating header, then send each fragment (in order).
	*/
	m_adj(m0, hlen + firstlen - ip->ip_len);
	ip->ip_len = htons((u_short)(hlen + firstlen));
	ip->ip_off = htons((u_short)IP_MF);
	ip->ip_sum = 0;
	ip->ip_sum = in_cksum(m0, hlen);
	sendorfree:
	for (m = m0; m; m = m0) {
	m0 = m->m_act;
	m->m_act = 0;
	if (error == 0)
	error = (*ifp->if_output)(ifp, m,
	(struct sockaddr *)dst);
	else
	FREE_MB_T(m);
	}
	}
	done:
	if (!error)
	ipf_frouteok[0]++;
	else
	ipf_frouteok[1]++;

	if (ro->ro_rt != NULL) {
	RTFREE(ro->ro_rt);
	}
	return 0;
	bad:
	if (error == EMSGSIZE) {
	sifp = fin->fin_ifp;
	code = fin->fin_icode;
	fin->fin_icode = ICMP_UNREACH_NEEDFRAG;
	fin->fin_ifp = ifp;
	(void) ipf_send_icmp_err(ICMP_UNREACH, fin, 1);
	fin->fin_ifp = sifp;
	fin->fin_icode = code;
	}
	FREE_MB_T(m);
	goto done;
	}


	int
	ipf_verifysrc(fin)
	fr_info_t *fin;
	{
	struct sockaddr_in *dst;
	struct route iproute;
	void *rtifp;

	bzero((char *)&iproute, sizeof(iproute));
	dst = (struct sockaddr_in *)&iproute.ro_dst;
	dst->sin_family = AF_INET;
	dst->sin_addr.s_addr = fin->fin_saddr;
	rtalloc(&iproute);
	if (iproute.ro_rt == NULL)
	return 0;
	rtifp = iproute.ro_rt->rt_ifp;
	RTFREE(iproute.ro_rt);
	return (fin->fin_ifp == rtifp);
	}


	/*
	* return the first IP Address associated with an interface
	*/
	int
	ipf_ifpaddr(softc, v, atype, ifptr, inp, inpmask)
	ipf_main_softc_t *softc;
	int v, atype;
	void *ifptr;
	i6addr_t inp, inpmask;
	{
	struct sockaddr_in sin, mask;
	struct in_ifaddr *ia;
	struct ifnet *ifp;

	if ((ifptr == NULL) \|\| (ifptr == (void *)-1))
	return -1;

	ifp = ifptr;
	if (ifp == NULL)
	return -1;

	for (ia = in_ifaddr; ia != NULL; ia = ia->ia_next)
	if (ia->ia_ifp == ifp) {
	sin = (struct sockaddr_in *)&ia->ia_addr;
	break;
	}

	if (ia == NULL)
	return -1;

	if (atype == FRI_BROADCAST)
	sin = (struct sockaddr_in *)&ia->ia_broadaddr;
	else if (atype == FRI_PEERADDR)
	sin = (struct sockaddr_in *)&ia->ia_dstaddr;
	mask = (struct sockaddr_in *)&ia->ia_subnetmask;

	return ipf_ifpfillv4addr(atype, sin, mask, &inp->in4, &inpmask->in4);
	}


	u_32_t
	ipf_newisn(fin)
	fr_info_t *fin;
	{
	static iss_seq_off = 0;
	u_char hash[16];
	u_32_t newiss;
	MD5_CTX ctx;

	/*
	* Compute the base value of the ISS. It is a hash
	* of (saddr, sport, daddr, dport, secret).
	*/
	MD5Init(&ctx);

	MD5Update(&ctx, (u_char *) &fin->fin_fi.fi_src,
	sizeof(fin->fin_fi.fi_src));
	MD5Update(&ctx, (u_char *) &fin->fin_fi.fi_dst,
	sizeof(fin->fin_fi.fi_dst));
	MD5Update(&ctx, (u_char *) &fin->fin_dat, sizeof(fin->fin_dat));

	MD5Update(&ctx, ipf_iss_secret, sizeof(ipf_iss_secret));

	MD5Final(hash, &ctx);

	memcpy(&newiss, hash, sizeof(newiss));

	/*
	* Now increment our "timer", and add it in to
	* the computed value.
	*
	* XXX Use `addin'?
	* XXX TCP_ISSINCR too large to use?
	*/
	iss_seq_off += 0x00010000;
	newiss += iss_seq_off;
	return newiss;
	}


	/* ------------------------------------------------------------------------ */
	/* Function: ipf_nextipid */
	/* Returns: int - 0 == success, -1 == error (packet should be droppped) */
	/* Parameters: fin(I) - pointer to packet information */
	/* */
	/* Returns the next IPv4 ID to use for this packet. */
	/* ------------------------------------------------------------------------ */
	INLINE u_short
	ipf_nextipid(fin)
	fr_info_t *fin;
	{
	u_short id;

	id = ipid++;

	return id;
	}


	INLINE int
	ipf_checkv4sum(fin)
	fr_info_t *fin;
	{
	if ((fin->fin_flx & FI_NOCKSUM) != 0)
	return 0;

	if ((fin->fin_flx & FI_SHORT) != 0)
	return 1;

	if (fin->fin_cksum != FI_CK_NEEDED)
	return (fin->fin_cksum > FI_CK_NEEDED) ? 0 : -1;

	if (ipf_checkl4sum(fin) == -1) {
	fin->fin_flx \|= FI_BAD;
	return -1;
	}
	return 0;
	}


	/* ------------------------------------------------------------------------ */
	/* Function: ipf_pullup */
	/* Returns: NULL == pullup failed, else pointer to protocol header */
	/* Parameters: xmin(I)- pointer to buffer where data packet starts */
	/* fin(I) - pointer to packet information */
	/* len(I) - number of bytes to pullup */
	/* */
	/* Attempt to move at least len bytes (from the start of the buffer) into a */
	/* single buffer for ease of access. Operating system native functions are */
	/* used to manage buffers - if necessary. If the entire packet ends up in */
	/* a single buffer, set the FI_COALESCE flag even though ipf_coalesce() has */
	/* not been called. Both fin_ip and fin_dp are updated before exiting _IF_ */
	/* and ONLY if the pullup succeeds. */
	/* */
	/* We assume that 'xmin' is a pointer to a buffer that is part of the chain */
	/* of buffers that starts at fin->fin_mp. /
	/* ------------------------------------------------------------------------ */
	void *
	ipf_pullup(xmin, fin, len)
	mb_t *xmin;
	fr_info_t *fin;
	int len;
	{
	int out = fin->fin_out, dpoff, ipoff;
	mb_t *m = xmin;
	char *ip;

	if (m == NULL)
	return NULL;

	ip = (char *)fin->fin_ip;
	if ((fin->fin_flx & FI_COALESCE) != 0)
	return ip;

	ipoff = fin->fin_ipoff;
	if (fin->fin_dp != NULL)
	dpoff = (char )fin->fin_dp - (char )ip;
	else
	dpoff = 0;

	if (M_LEN(m) < len) {
	mb_t n = fin->fin_mp;

	if (m != n) {
	for (; n->m_next != m; n = n->m_next)
	;
	} else {
	n = NULL;
	}

	if (len > MLEN) {
	FREE_MB_T(*fin->fin_mp);
	m = NULL;
	n = NULL;
	} else {
	m = m_pullup(m, len);
	}

	if (n != NULL)
	n->m_next = m;

	if (m == NULL) {
	if (n != NULL) {
	FREE_MB_T(*fin->fin_mp);
	}
	*fin->fin_mp = NULL;
	fin->fin_m = NULL;
	return NULL;
	}

	if (n == NULL)
	*fin->fin_mp = m;

	while (M_LEN(m) == 0) {
	m = m->m_next;
	}

	fin->fin_m = m;
	ip = MTOD(m, char *) + ipoff;

	fin->fin_ip = (ip_t *)ip;
	if (fin->fin_dp != NULL)
	fin->fin_dp = (char *)fin->fin_ip + dpoff;
	}

	if (len == fin->fin_plen)
	fin->fin_flx \|= FI_COALESCE;
	return ip;
	}


	int
	ipf_inject(fin, m)
	fr_info_t *fin;
	mb_t *m;
	{
	int error;

	if (fin->fin_out == 0) {
	struct ifqueue *ifq;

	ifq = &ipintrq;

	if (IF_QFULL(ifq)) {
	IF_DROP(ifq);
	FREE_MB_T(m);
	error = ENOBUFS;
	} else {
	IF_ENQUEUE(ifq, m);
	error = 0;
	}
	} else {
	error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL);
	}

	return error;
	}


	/*
	* In the face of no kernel random function, this is implemented...it is
	* not meant to be random, just a fill in.
	*/
	int
	ipf_random()
	{
	static int last = 0;
	static int calls = 0;
	struct timeval tv;
	int number;

	GETKTIME(&tv);
	last *= tv.tv_usec + calls++;
	last += (int)&range * ipf_ticks;
	number = last + tv.tv_sec;
	return number;
	}


	u_short
	ipf_pcksum(fin, hlen, sum)
	{
	u_short sum2;

	slen = fin->fin_plen - hlen;
	m->m_off += hlen;
	m->m_len -= hlen;
	sum2 = in_cksum(fin->fin_m, slen);
	m->m_len += hlen;
	m->m_off -= hlen;
	/*
	* Both sum and sum2 are partial sums, so combine them together.
	*/
	sum += ~sum2 & 0xffff;
	while (sum > 0xffff)
	sum = (sum & 0xffff) + (sum >> 16);
	sum2 = ~sum & 0xffff;
	return sum2;
	}