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Date:      Mon, 18 Feb 2002 09:31:13 -0800
From:      "Crist J. Clark" <crist.clark@attbi.com>
To:        "Michael R. Wayne" <wayne@staff.msen.com>
Cc:        freebsd-hackers@FreeBSD.ORG
Subject:   Re: Odd ipfw behaviour
Message-ID:  <20020218093113.H48401@blossom.cjclark.org>
In-Reply-To: <20020218120117.E96593@staff.msen.com>; from wayne@staff.msen.com on Mon, Feb 18, 2002 at 12:01:17PM -0500
References:  <200202152309.SAA00831@manor.msen.com> <20020216004721.B36782@blossom.cjclark.org> <20020218034112.D96593@staff.msen.com> <20020218054946.W48401@blossom.cjclark.org> <20020218120117.E96593@staff.msen.com>

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On Mon, Feb 18, 2002 at 12:01:17PM -0500, Michael R. Wayne wrote:
> On Mon, Feb 18, 2002 at 05:49:46AM -0800, Crist J. Clark wrote:
> > What precise version of FreeBSD are you running, BTW?
> 
> 4.5 RELEASE, as stated in original message.

Do these patches help?

Index: ip_input.c
===================================================================
RCS file: /export/ncvs/src/sys/netinet/ip_input.c,v
retrieving revision 1.130.2.33
diff -u -r1.130.2.33 ip_input.c
--- ip_input.c	14 Feb 2002 11:19:57 -0000	1.130.2.33
+++ ip_input.c	18 Feb 2002 17:19:24 -0000
@@ -1618,21 +1618,29 @@
 	int error, type = 0, code = 0;
 	struct mbuf *mcopy;
 	n_long dest;
+	struct in_addr pkt_dst;
 	struct ifnet *destifp;
 #ifdef IPSEC
 	struct ifnet dummyifp;
 #endif
 
 	dest = 0;
+	/*
+	 * Cache the destination address of the packet; this may be
+	 * changed by use of 'ipfw fwd'.
+	 */
+	pkt_dst = ip_fw_fwd_addr == NULL ?
+	    ip->ip_dst : ip_fw_fwd_addr->sin_addr;
+
 #ifdef DIAGNOSTIC
 	if (ipprintfs)
 		printf("forward: src %lx dst %lx ttl %x\n",
-		    (u_long)ip->ip_src.s_addr, (u_long)ip->ip_dst.s_addr,
+		    (u_long)ip->ip_src.s_addr, (u_long)pkt_dst.s_addr,
 		    ip->ip_ttl);
 #endif
 
 
-	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
+	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(pkt_dst) == 0) {
 		ipstat.ips_cantforward++;
 		m_freem(m);
 		return;
@@ -1651,14 +1659,14 @@
 
 	sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
 	if ((rt = ipforward_rt.ro_rt) == 0 ||
-	    ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
+	    pkt_dst.s_addr != sin->sin_addr.s_addr) {
 		if (ipforward_rt.ro_rt) {
 			RTFREE(ipforward_rt.ro_rt);
 			ipforward_rt.ro_rt = 0;
 		}
 		sin->sin_family = AF_INET;
 		sin->sin_len = sizeof(*sin);
-		sin->sin_addr = ip->ip_dst;
+		sin->sin_addr = pkt_dst;
 
 		rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
 		if (ipforward_rt.ro_rt == 0) {
@@ -1704,7 +1712,7 @@
 	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
 	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
 	    satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
-	    ipsendredirects && !srcrt) {
+	    ipsendredirects && !srcrt && !ip_fw_fwd_addr) {
 #define	RTA(rt)	((struct in_ifaddr *)(rt->rt_ifa))
 		u_long src = ntohl(ip->ip_src.s_addr);
 
@@ -1713,7 +1721,7 @@
 		    if (rt->rt_flags & RTF_GATEWAY)
 			dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
 		    else
-			dest = ip->ip_dst.s_addr;
+			dest = pkt_dst.s_addr;
 		    /* Router requirements says to only send host redirects */
 		    type = ICMP_REDIRECT;
 		    code = ICMP_REDIRECT_HOST;
Index: ip_output.c
===================================================================
RCS file: /export/ncvs/src/sys/netinet/ip_output.c,v
retrieving revision 1.99.2.25
diff -u -r1.99.2.25 ip_output.c
--- ip_output.c	1 Feb 2002 10:42:09 -0000	1.99.2.25
+++ ip_output.c	18 Feb 2002 17:12:33 -0000
@@ -128,6 +128,7 @@
 	struct sockaddr_in *dst;
 	struct in_ifaddr *ia = NULL;
 	int isbroadcast, sw_csum;
+	struct in_addr pkt_dst;
 #ifdef IPSEC
 	struct socket *so = NULL;
 	struct secpolicy *sp = NULL;
@@ -191,6 +192,9 @@
 		hlen = len;
 	}
 	ip = mtod(m, struct ip *);
+	pkt_dst = ip_fw_fwd_addr == NULL
+		? ip->ip_dst : ip_fw_fwd_addr->sin_addr;
+
 	/*
 	 * Fill in IP header.
 	 */
@@ -219,14 +223,14 @@
 	 * and is still up.  If not, free it and try again.
 	 */
 	if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
-	   dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
+	   dst->sin_addr.s_addr != pkt_dst.s_addr)) {
 		RTFREE(ro->ro_rt);
 		ro->ro_rt = (struct rtentry *)0;
 	}
 	if (ro->ro_rt == 0) {
 		dst->sin_family = AF_INET;
 		dst->sin_len = sizeof(*dst);
-		dst->sin_addr = ip->ip_dst;
+		dst->sin_addr = pkt_dst;
 	}
 	/*
 	 * If routing to interface only,
@@ -278,7 +282,7 @@
 		else
 			isbroadcast = in_broadcast(dst->sin_addr, ifp);
 	}
-	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
+	if (IN_MULTICAST(ntohl(pkt_dst.s_addr))) {
 		struct in_multi *inm;
 
 		m->m_flags |= M_MCAST;
@@ -318,7 +322,7 @@
 				ip->ip_src = IA_SIN(ia)->sin_addr;
 		}
 
-		IN_LOOKUP_MULTI(ip->ip_dst, ifp, inm);
+		IN_LOOKUP_MULTI(pkt_dst, ifp, inm);
 		if (inm != NULL &&
 		   (imo == NULL || imo->imo_multicast_loop)) {
 			/*
@@ -582,8 +586,9 @@
 
 	/*
 	 * Check with the firewall...
+	 * but not if we are already being fwd'd from a firewall.
 	 */
-	if (fw_enable && IPFW_LOADED) {
+	if (fw_enable && IPFW_LOADED && !ip_fw_fwd_addr) {
 		struct sockaddr_in *old = dst;
 
 		off = ip_fw_chk_ptr(&ip,
@@ -774,6 +779,7 @@
                 goto done;
 	}
 
+	ip_fw_fwd_addr = NULL;
 pass:
 	m->m_pkthdr.csum_flags |= CSUM_IP;
 	sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_hwassist;

-- 
Crist J. Clark                     |     cjclark@alum.mit.edu
                                   |     cjclark@jhu.edu
http://people.freebsd.org/~cjc/    |     cjc@freebsd.org

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