Fix segfault in issue #463 (#464)

src/sn_utils.c

@@ -1068,11 +1068,6 @@ static int process_udp(n2n_sn_t * sss,
       n2n_sock_t 		      *tmp_sock;
       n2n_mac_t 		      *tmp_mac;
 
-      if(from_supernode != comm->is_federation) {
-        traceEvent(TRACE_DEBUG, "process_udp dropped REGISTER_SUPER: from_supernode value doesn't correspond to the internal federation marking");
-	return -1;
-      }
-
       memset(&ack, 0, sizeof(n2n_REGISTER_SUPER_ACK_t));
 
       /* Edge/supernode requesting registration with us.  */
@@ -1154,6 +1149,11 @@ static int process_udp(n2n_sn_t * sss,
 	ack.sock.port = ntohs(sender_sock->sin_port);
 	memcpy(ack.sock.addr.v4, &(sender_sock->sin_addr.s_addr), IPV4_SIZE);
 	      
+        if(from_supernode != comm->is_federation) {
+          traceEvent(TRACE_DEBUG, "process_udp dropped REGISTER_SUPER: from_supernode value doesn't correspond to the internal federation marking");
+	  return -1;
+        }
+
 	/* Add sender's data to federation (or update it) */
 	if(comm->is_federation == IS_FEDERATION) {
 	  p = add_sn_to_federation_by_mac_or_sock(sss,&(ack.sock),&(reg.edgeMac));