Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

===================================================================
RCS file: /ftp/cvs/cvsroot/src/sys/netinet/ip_input.c,v
retrieving revision 1.3.4.2
retrieving revision 1.4
diff -u -p -r1.3.4.2 -r1.4
--- src/sys/netinet/ip_input.c	1993/11/14 17:54:46	1.3.4.2
+++ src/sys/netinet/ip_input.c	1993/12/06 04:59:37	1.4
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)ip_input.c	7.19 (Berkeley) 5/25/91
- *	$Id: ip_input.c,v 1.3.4.2 1993/11/14 17:54:46 mycroft Exp $
+ *	$Id: ip_input.c,v 1.4 1993/12/06 04:59:37 hpeyerl Exp $
  */
 
 #include "param.h"
@@ -45,8 +45,6 @@
 #include "time.h"
 #include "kernel.h"
 
-#include "machine/cpu.h"
-
 #include "../net/if.h"
 #include "../net/route.h"
 
@@ -144,7 +142,7 @@ ipintr()
 	register struct ipq *fp;
 	register struct in_ifaddr *ia;
 	int hlen, s;
-#ifdef DIAGNOSTIC
+#ifdef PARANOID
 	static int busy = 0;
 
 	if (busy)
@@ -160,7 +158,7 @@ next:
 	IF_DEQUEUE(&ipintrq, m);
 	splx(s);
 	if (m == 0) {
-#ifdef DIAGNOSTIC
+#ifdef PARANOID
 		--busy;
 #endif
 		return;
@@ -269,6 +267,53 @@ next:
 				goto ours;
 		}
 	}
+#ifdef MULTICAST
+	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
+		struct in_multi *inm;
+#ifdef MROUTING
+		extern struct socket *ip_mrouter;
+
+		if (ip_mrouter) {
+			/*
+			 * If we are acting as a multicast router, all
+			 * incoming multicast packets are passed to the
+			 * kernel-level multicast forwarding function.
+			 * The packet is returned (relatively) intact; if
+			 * ip_mforward() returns a non-zero value, the packet
+			 * must be discarded, else it may be accepted below.
+			 *
+			 * (The IP ident field is put in the same byte order
+			 * as expected when ip_mforward() is called from
+			 * ip_output().)
+			 */
+			ip->ip_id = htons(ip->ip_id);
+			if (ip_mforward(ip, m->m_pkthdr.rcvif, m) != 0) {
+				m_freem(m);
+				goto next;
+			}
+			ip->ip_id = ntohs(ip->ip_id);
+
+			/*
+			 * The process-level routing demon needs to receive
+			 * all multicast IGMP packets, whether or not this
+			 * host belongs to their destination groups.
+			 */
+			if (ip->ip_p == IPPROTO_IGMP)
+				goto ours;
+		}
+#endif
+		/*
+		 * See if we belong to the destination multicast group on the
+		 * arrival interface.
+		 */
+		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
+		if (inm == NULL) {
+			m_freem(m);
+			goto next;
+		}
+		goto ours;
+	}
+#endif
 	if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
 		goto ours;
 	if (ip->ip_dst.s_addr == INADDR_ANY)