[#1301] Return zero for invalid identifiers

backend/util/util.go

@@ -111,8 +111,13 @@ func IsHexIdentifier(text string) bool {
 
 // Counts the number of bytes in the provided hex identifier.
 // It doesn't check if the input is a valid hex identifier. It may return
-// a value even for malformed input.
+// a value even for malformed input. Returns zero if the input is not a hex
+// identifier.
 func CountHexIdentifierBytes(text string) int {
+	if !IsHexIdentifier(text) {
+		return 0
+	}
+
 	// Remove any whitespace and colons.
 	replacer := strings.NewReplacer(" ", "", ":", "")
 	identifier := replacer.Replace(text)

backend/util/util_test.go

@@ -106,12 +106,12 @@ func TestCountHexIdentifierBytes(t *testing.T) {
 	// Invalid output for invalid input.
 	require.Zero(t, CountHexIdentifierBytes(" "))
 	require.Zero(t, CountHexIdentifierBytes(""))
-	require.Equal(t, 3, CountHexIdentifierBytes("1234gh"))
-	require.Equal(t, 2, CountHexIdentifierBytes("12:56:"))
-	require.Equal(t, 2, CountHexIdentifierBytes("12:56:9"))
-	require.Equal(t, 2, CountHexIdentifierBytes("ab,cd"))
-	require.Equal(t, 2, CountHexIdentifierBytes("ab: cd"))
-	require.Equal(t, 2, CountHexIdentifierBytes("abcde"))
+	require.Zero(t, CountHexIdentifierBytes("1234gh"))
+	require.Zero(t, CountHexIdentifierBytes("12:56:"))
+	require.Zero(t, CountHexIdentifierBytes("12:56:9"))
+	require.Zero(t, CountHexIdentifierBytes("ab,cd"))
+	require.Zero(t, CountHexIdentifierBytes("ab: cd"))
+	require.Zero(t, CountHexIdentifierBytes("abcde"))
 }
 
 // Check if BytesToHex works.