#include<core.p4>
 #include<v1model.p4>
 
 const bit<16> TYPE_IPV6 = 0x08DD;//ipv6在以太网中的id
 
 /*HEADERS*/
 
 typedef bit<9> egressSpec_t;
 typedef bit<48> macAddr_t;
 
 header ethernet_t{
     macAddr_t dstAddr;
     macAddr_t srcAddr;
     bit<16> etherType;
 }
  
 header ipv6_t{
     bit<4> version;
     bit<8> trafficClass;
     bit<20> flowLabel;
     bit<16> payLoadLen;
     bit<8> nextHdr;
     bit<8> hopLimit;
     bit<128> srcAddr;
     bit<128> dstAddr;
 }
 
 struct metadata{
 }
 
 struct headers{
     ethernet_t ethernet;
     ipv6_t ipv6;
 }
 
 /*PARSER*/
 
 parser MyParser(packet_in packet,out headers hdr,inout metadata meta,inout standard_metadata_t standard_metadata){
     state start{
         transition parse_ethernet;//start开始先以底层eth解析
     }
     
     state parse_ethernet{
         packet.extract(hdr.ethernet);
         transition select(hdr.ethernet.etherType){
             TYPE_IPV6:parse_ipv6;//转至ipv6解析
             default:accept;
         }
     }
     
     state parse_ipv6{
         packet.extract(hdr.ipv6);
         transition accept;
     }
 }
 
 /*CHECKSUM VERIFICATION*/
 
control MyVerifyChecksum(inout headers hdr,inout metadata meta){
    apply{}
}
 
 /*INGRESS PROCESSING*/
 
 control MyIngress(inout headers hdr,inout metadata meta,inout standard_metadata_t standard_metadata){
     action drop(){
         mark_to_drop();//将要丢弃的包标记为丢弃
     }
     
     action ipv6_forward(macAddr_t dstAddr,egressSpec_t port){
         standard_metadata.egress_spec = port;
         hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
         hdr.ethernet.dstAddr = dstAddr;
         hdr.ipv6.hopLimit = hdr.ipv6.hopLimit - 1;//这个类似ipv4中ttl，为0时就超时
     }
     
     table ipv6_lpm{
         key = {
             hdr.ipv6.dstAddr: lpm;//lpm是最长前缀匹配，exact完全匹配，ternary三元匹配
         }
         
         actions = {
             ipv6_forward;//转发
             drop;//丢弃
             NoAction;//空动作
         }
         
         size = 1024;//流表项容量
         
         default_action = drop();//table miss则丢弃
     }
     
     apply{
         if(hdr.ipv6.isValid()){
             ipv6_lpm.apply();
         }
     }
 }
 
 /*EGRESS PROCESSING*/
 
 control MyEgress(inout headers hdr,inout metadata meta,inout standard_metadata_t standard_metadata){
     apply{}
 }
 
 /*CHECKSUM COMPUTATION*/
 
 control MyComputeChecksum(inout headers hdr,inout metadata meta){
     apply{}
 }
 
 /*DEPARSER*/
 
 control MyDeparser(packet_out packet,in headers hdr){
     apply{
         packet.emit(hdr.ethernet);
         packet.emit(hdr.ipv6);
     }
 }
 
 /*SWITCH*/
 
 V1Switch(
 MyParser(),
 MyVerifyChecksum(),
 MyIngress(),
 MyEgress(),
 MyComputeChecksum(),
 MyDeparser()
 )main;