feat: add merkletreeparent util functions

transaction/merkletreeparent.go

@@ -0,0 +1,54 @@
+package transaction
+
+import (
+	"encoding/hex"
+
+	"github.com/bitcoin-sv/go-sdk/chainhash"
+	crypto "github.com/bitcoin-sv/go-sdk/primitives/hash"
+	"github.com/bitcoin-sv/go-sdk/util"
+)
+
+// MerkleTreeParentStr returns the Merkle Tree parent of two Merkle
+// Tree children using hex strings instead of just bytes.
+func MerkleTreeParentStr(leftNode, rightNode string) (string, error) {
+	l, err := hex.DecodeString(leftNode)
+	if err != nil {
+		return "", err
+	}
+	r, err := hex.DecodeString(rightNode)
+	if err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(MerkleTreeParent(l, r)), nil
+}
+
+// MerkleTreeParent returns the Merkle Tree parent of two Merkle
+// Tree children.
+func MerkleTreeParent(leftNode, rightNode []byte) []byte {
+	// swap endianness before concatenating
+	l := util.ReverseBytes(leftNode)
+	r := util.ReverseBytes(rightNode)
+
+	// concatenate leaves
+	concat := append(l, r...)
+
+	// hash the concatenation
+	hash := crypto.Sha256d(concat)
+
+	// swap endianness at the end and convert to hex string
+	return util.ReverseBytes(hash)
+}
+
+// MerkleTreeParentBytes returns the Merkle Tree parent of two Merkle Tree children.
+// The expectation is that the bytes are not reversed.
+func MerkleTreeParentBytes(l *chainhash.Hash, r *chainhash.Hash) *chainhash.Hash {
+	lb := l.CloneBytes()
+	rb := r.CloneBytes()
+	concat := append(lb, rb...)
+	hash, err := chainhash.NewHash(crypto.Sha256d(concat))
+	if err != nil {
+		return &chainhash.Hash{}
+	}
+	return hash
+}

transaction/merkletreeparent_test.go

@@ -0,0 +1,32 @@
+package transaction_test
+
+import (
+	"encoding/hex"
+	"testing"
+
+	"github.com/bitcoin-sv/go-sdk/transaction"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetMerkleTreeParentStr(t *testing.T) {
+	leftNode := "d6c79a6ef05572f0cb8e9a450c561fc40b0a8a7d48faad95e20d93ddeb08c231"
+	rightNode := "b1ed931b79056438b990d8981ba46fae97e5574b142445a74a44b978af284f98"
+
+	expected := "b0d537b3ee52e472507f453df3d69561720346118a5a8c4d85ca0de73bc792be"
+
+	parent, err := transaction.MerkleTreeParentStr(leftNode, rightNode)
+
+	require.NoError(t, err)
+	require.Equal(t, expected, parent)
+}
+
+func TestGetMerkleTreeParent(t *testing.T) {
+	leftNode, _ := hex.DecodeString("d6c79a6ef05572f0cb8e9a450c561fc40b0a8a7d48faad95e20d93ddeb08c231")
+	rightNode, _ := hex.DecodeString("b1ed931b79056438b990d8981ba46fae97e5574b142445a74a44b978af284f98")
+
+	expected, _ := hex.DecodeString("b0d537b3ee52e472507f453df3d69561720346118a5a8c4d85ca0de73bc792be")
+
+	parent := transaction.MerkleTreeParent(leftNode, rightNode)
+
+	require.Equal(t, expected, parent)
+}