How to resolve ENS on-chain

ENSLookup.sol

interface DefaultReverseResolver{
  function name(bytes32 node) external view returns (string memory);
}

interface ENS{
  function resolver(bytes32 node) external view returns (address);
}

interface ReverseRegistrar{
  function node(address addr) external pure returns (bytes32);
}

contract ENSLookup{
  ENS public ens = ENS( 0x00000000000C2E074eC69A0dFb2997BA6C7d2e1e );
  ReverseRegistrar public reverseResolver = ReverseRegistrar( 0x084b1c3c81545d370f3634392de611caabff8148 );

  function lookup( address addr ) external view returns( string memory ){
    bytes32 node = reverseResolver.node( addr );
    address addr = ens.resolver( node );
    if( addr == address(0) ){
      return addr.toHexString();
    }
    else{
      return DefaultReverseResolver( addr ).name( node );
    }
  }
}