Add hash to ConsensusParams

types/params.go

@@ -2,6 +2,8 @@ package types
 
 import (
 	"github.com/pkg/errors"
+
+	"github.com/tendermint/tmlibs/merkle"
 )
 
 const (
@@ -85,3 +87,16 @@ func (params *ConsensusParams) Validate() error {
 	}
 	return nil
 }
+
+// Hash returns a merkle hash of the parameters to store
+// in the block header
+func (params *ConsensusParams) Hash() []byte {
+	return merkle.SimpleHashFromMap(map[string]interface{}{
+		"block_gossip_part_size_bytes": params.BlockGossipParams.BlockPartSizeBytes,
+		"block_size_max_bytes":         params.BlockSizeParams.MaxBytes,
+		"block_size_max_gas":           params.BlockSizeParams.MaxGas,
+		"block_size_max_txs":           params.BlockSizeParams.MaxTxs,
+		"tx_size_max_bytes":            params.TxSizeParams.MaxBytes,
+		"tx_size_max_gas":              params.TxSizeParams.MaxGas,
+	})
+}

types/params_test.go

@@ -1,6 +1,8 @@
 package types
 
 import (
+	"bytes"
+	"sort"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -38,3 +40,49 @@ func TestConsensusParamsValidation(t *testing.T) {
 		}
 	}
 }
+
+func makeParams(blockBytes, blockTx, blockGas, txBytes,
+	txGas, partSize int) ConsensusParams {
+
+	return ConsensusParams{
+		BlockSizeParams: BlockSizeParams{
+			MaxBytes: blockBytes,
+			MaxTxs:   blockTx,
+			MaxGas:   blockGas,
+		},
+		TxSizeParams: TxSizeParams{
+			MaxBytes: txBytes,
+			MaxGas:   txGas,
+		},
+		BlockGossipParams: BlockGossipParams{
+			BlockPartSizeBytes: partSize,
+		},
+	}
+}
+
+func TestConsensusParamsHash(t *testing.T) {
+	params := []ConsensusParams{
+		makeParams(1, 2, 3, 4, 5, 6),
+		makeParams(7, 2, 3, 4, 5, 6),
+		makeParams(1, 7, 3, 4, 5, 6),
+		makeParams(1, 2, 7, 4, 5, 6),
+		makeParams(1, 2, 3, 7, 5, 6),
+		makeParams(1, 2, 3, 4, 7, 6),
+		makeParams(1, 2, 3, 4, 5, 7),
+		makeParams(6, 5, 4, 3, 2, 1),
+	}
+
+	hashes := make([][]byte, len(params))
+	for i := range params {
+		hashes[i] = params[i].Hash()
+	}
+
+	// make sure there are no duplicates...
+	// sort, then check in order for matches
+	sort.Slice(hashes, func(i, j int) bool {
+		return bytes.Compare(hashes[i], hashes[j]) < 0
+	})
+	for i := 0; i < len(hashes)-1; i++ {
+		assert.NotEqual(t, hashes[i], hashes[i+1])
+	}
+}