ipv4.up4

/*
 * Author: Hardik Soni
 * Email: hks57@cornell.edu
 */

#include"msa.up4"
#include"common.up4"

header ipv4_h {
  // bit<4> version;
  // bit<4> ihl;
  bit<8> ihl_version;
  bit<8> diffserv;
  bit<16> totalLen;
  bit<16> identification;
  bit<3> flags;
  bit<13> fragOffset;
  bit<8> ttl;
  bit<8> protocol;
  bit<16> hdrChecksum;
  bit<32> srcAddr;
  bit<32> dstAddr; 
}

struct ipv4_hdr_t {
  ipv4_h ipv4;
}

cpackage IPv4 : implements Unicast<ipv4_hdr_t, empty_t, empty_t, bit<16>, empty_t> {

  parser micro_parser(extractor ex, pkt p, im_t im, out ipv4_hdr_t hdr, 
                      inout empty_t meta, in empty_t ia, inout empty_t ioa) {
    state start {
      ex.extract(p, hdr.ipv4);
      transition accept;
    }
  }

  control micro_control(pkt p, im_t im, inout ipv4_hdr_t hdr, inout empty_t m,
                          in empty_t e, out bit<16> nexthop, 
                          inout empty_t ioa) { // nexthop out arg
    action process(bit<16> nh) {
      // disabling for pings
      // hdr.ipv4.ttl = hdr.ipv4.ttl - 1;

      nexthop = nh;  // setting out param
    }
    action default_act() {
      nexthop = 0; 
    }

    table ipv4_lpm_tbl {
      key = { 
        // Why not lpm? because can't specify prefix length in const entries
        hdr.ipv4.dstAddr : exact; 
        hdr.ipv4.diffserv : ternary;
      } 
      actions = { 
        process; 
        default_act;
      }
      const entries = {
        // v1model mininet suitable entries
        // 10.0.1.1, _
        (32w167772417, _) : process(16w1);
        // 10.0.2.1, _
        (32w167772673, _): process(16w2);

        // for tofino setup at cornell-netlab
        // 10.0.0.22
        (32w167772182, _) : process(16w22);
        // 10.0.0.23
        (32w167772183, _) : process(16w23);
      }
      default_action = default_act;

    }
    apply { 
      ipv4_lpm_tbl.apply(); 
    }
  }

  control micro_deparser(emitter em, pkt p, in ipv4_hdr_t h) {
    apply { 
      em.emit(p, h.ipv4); 
    }
  }
}