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
rcsdiff: /ftp/cvs/cvsroot/src/sys/netinet/ip_input.c,v: warning: Unknown phrases like `commitid ...;' are present.
retrieving revision 1.1
retrieving revision 1.4
diff -u -p -r1.1 -r1.4
--- src/sys/netinet/ip_input.c	1993/03/21 09:45:37	1.1
+++ src/sys/netinet/ip_input.c	1993/12/06 04:59:37	1.4
@@ -30,7 +30,8 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)ip_input.c	7.19 (Berkeley) 5/25/91
+ *	from: @(#)ip_input.c	7.19 (Berkeley) 5/25/91
+ *	$Id: ip_input.c,v 1.4 1993/12/06 04:59:37 hpeyerl Exp $
  */
 
 #include "param.h"
@@ -141,7 +142,13 @@ ipintr()
 	register struct ipq *fp;
 	register struct in_ifaddr *ia;
 	int hlen, s;
+#ifdef PARANOID
+	static int busy = 0;
 
+	if (busy)
+		panic("ipintr: called recursively\n");
+	++busy;
+#endif
 next:
 	/*
 	 * Get next datagram off input queue and get IP header
@@ -150,8 +157,12 @@ next:
 	s = splimp();
 	IF_DEQUEUE(&ipintrq, m);
 	splx(s);
-	if (m == 0)
+	if (m == 0) {
+#ifdef PARANOID
+		--busy;
+#endif
 		return;
+	}
 #ifdef	DIAGNOSTIC
 	if ((m->m_flags & M_PKTHDR) == 0)
 		panic("ipintr no HDR");
@@ -256,6 +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)