Change protocol in case of icmp6->icmp

p4src/static-mapping.p4

@@ -71,11 +71,25 @@ control MyIngress(inout headers hdr,
         hdr.ipv4.src_addr       = src;
 
         hdr.ipv4.ttl            = hdr.ipv6.hop_limit;
+
         hdr.ipv4.protocol       = hdr.ipv6.next_header;
 
+        switch(hdr.ipv6.next_header) {
+            PROTO_ICMP6: {
+                nat64_icmp6;
+            }
+        }
+
         hdr.ipv6.setInvalid();
 	}
 
+    action nat64_icmp6()
+    {
+
+        hdr.ipv4.protocol = PROTO_ICMP; // overwrite generic same protocol assumption
+
+    }
+
     /* NAT46: protocol unspecific changes */
 	action nat46_generic(ipv6_addr_t src, ipv6_addr_t dst) {
 		hdr.ipv6.setValid();
@@ -383,7 +397,4 @@ MyIngress(),
 MyEgress(),
 MyComputeChecksum(),
 MyDeparser()
-) main;
-
-
-        //     truncate((bit<32>)22); //ether+cpu header
+) main;