cr

Author: bbroder-uji

crypto/statetrie/nibbles/nibbles.go

@@ -25,29 +25,23 @@ import (
 type Nibbles []byte
 
 const (
-	// evenIndicator for serialization when the last nibble in a byte array
-	// is part of the nibble array.
-	evenIndicator = 0x01
-	// oddIndicator for when it is not.
-	oddIndicator = 0x03
+	// oddIndicator for serialization when the last nibble in a byte array
+	// is not part of the nibble array.
+	oddIndicator = 0x01
+	// evenIndicator for when it is.
+	evenIndicator = 0x03
 )
 
 // MakeNibbles returns a nibble array from the byte array.  If oddLength is true,
-// the last 4 bits of the last byte of the array are ignored.
-func MakeNibbles(data []byte, oddLength bool) Nibbles {
-	return Unpack(data, oddLength)
-}
-
-// Unpack the byte array into a nibble array.  If oddLength is true, the last 4
-// bits of the last byte of the array are ignored.  Allocates a new byte
-// slice.
+// the last 4 bits of the last byte of the array are ignored.  
 //
 // [0x12, 0x30], true -> [0x1, 0x2, 0x3]
 // [0x12, 0x34], false -> [0x1, 0x2, 0x3, 0x4]
 // [0x12, 0x34], true -> [0x1, 0x2, 0x3]  <-- last byte last 4 bits ignored
 // [], false -> []
 // never to be called with [], true
-func Unpack(data []byte, oddLength bool) Nibbles {
+// Allocates a new byte slice.
+func MakeNibbles(data []byte, oddLength bool) Nibbles {
 	length := len(data) * 2
 	if oddLength {
 		length = length - 1
@@ -142,11 +136,11 @@ func Serialize(nyb Nibbles) (data []byte) {
 	output := make([]byte, length+1)
 	copy(output, p)
 	if h {
-		// 0x1 is the arbitrary odd length indicator
-		output[length] = evenIndicator
-	} else {
-		// 0x3 is the arbitrary even length indicator
+		// 0x01 is the odd length indicator
 		output[length] = oddIndicator
+	} else {
+		// 0x03 is the even length indicator
+		output[length] = evenIndicator
 	}
 
 	return output
@@ -159,10 +153,13 @@ func Deserialize(encoding []byte) (Nibbles, error) {
 	if length == 0 {
 		return nil, errors.New("invalid encoding")
 	}
-	if encoding[length-1] == evenIndicator {
-		ns = Unpack(encoding[:length-1], true)
-	} else if encoding[length-1] == oddIndicator {
-		ns = Unpack(encoding[:length-1], false)
+	if encoding[length-1] == oddIndicator {
+        if length == 1 {
+    		return nil, errors.New("invalid encoding")
+        }
+		ns = MakeNibbles(encoding[:length-1], true)
+	} else if encoding[length-1] == evenIndicator {
+		ns = MakeNibbles(encoding[:length-1], false)
 	} else {
 		return nil, errors.New("invalid encoding")
 	}

crypto/statetrie/nibbles/nibbles_test.go

@@ -60,17 +60,25 @@ func TestNibblesRandom(t *testing.T) {
 		packed, odd := Pack(nibbles)
 		require.Equal(t, odd, half)
 		require.Equal(t, packed, data)
-		unpacked := Unpack(packed, odd)
+		unpacked := MakeNibbles(packed, odd)
 		require.Equal(t, nibbles, unpacked)
 
 		packed, odd = Pack(nibbles2)
 		require.Equal(t, odd, half)
 		require.Equal(t, packed, data)
-		unpacked = Unpack(packed, odd)
+		unpacked = MakeNibbles(packed, odd)
 		require.Equal(t, nibbles2, unpacked)
 	}
 }
 
+func TestNibblesDeserialize(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+    enc := []byte{0x01}
+    _, err := Deserialize(enc)
+    require.Error(t, err, "should return invalid encoding error")
+}
+
 func TestNibbles(t *testing.T) {
 	partitiontest.PartitionTest(t)
 	t.Parallel()
@@ -121,7 +129,7 @@ func TestNibbles(t *testing.T) {
 		require.Equal(t, oddLength == (len(n)%2 == 1), true)
 		require.Equal(t, bytes.Equal(b, sampleNibblesPacked[i]), true)
 
-		unp := Unpack(b, oddLength)
+		unp := MakeNibbles(b, oddLength)
 		require.Equal(t, bytes.Equal(unp, n), true)
 
 	}