Bum traffic handling in transparent service chain

When the BUM traffic is received on transparent service chain
interface, it has to be dropped to avoid the loops in that
service chain network.
Checking-in on behalf of  Anand

Change-Id: Ic1b1a2f2c5716e2852582012963e6ee9934e9a1a
closes-bug: #1449166

dp-core/vr_datapath.c

@@ -495,6 +495,18 @@ vr_virtual_input(unsigned short vrf, struct vr_interface *vif,
         return 0;
     }
 
+    /*
+     * we really do not allow any broadcast packets from interfaces
+     * that are part of transparent service chain, since transparent
+     * service chain bridges packets across vrf (and hence loops can
+     * happen)
+     */
+    if ((pkt->vp_flags & VP_FLAG_MULTICAST) &&
+            (vif_is_service(vif))) {
+        vif_drop_pkt(vif, pkt, 1);
+        return 0;
+    }
+
     if (!vr_flow_forward(pkt->vp_if->vif_router, pkt, &fmd))
         return 0;