fix(utils): use Go 1.20+ unsafe.String in UnsafeCastToString and add upfront overflow check in CalculateMaxSize

pkg/utils/bytes.go

@@ -15,5 +15,5 @@ func Uint64ToBytes(i uint64) []byte {
 // to byteSlice will also modify the contents of the string, so it is the caller's responsibility
 // to ensure that the byte slice will not modified after the string is created.
 func UnsafeCastToString(byteSlice []byte) string {
-	return *(*string)(unsafe.Pointer(&byteSlice)) // #nosec G103
+	return unsafe.String(unsafe.SliceData(byteSlice), len(byteSlice))
 }

pkg/utils/calc.go

@@ -7,14 +7,16 @@ import (
 
 // CalculateMaxSize calculates the maximum size of a message that can be sent over the network.
 // add some extra bytes for header and service info
-// check possible overflow also
+// check possible overflow also using integer arithmetic
 func CalculateMaxSize(src int64) (int, error) {
 	if src <= 0 {
 		return 0, fmt.Errorf("src must be positive: %d", src)
 	}
-	finalVal := src + int64(float64(src)*0.2)
-	if finalVal < 0 || finalVal > math.MaxInt {
+	maxAllowed := int64(math.MaxInt)
+	overhead := src / 5
+	if src > maxAllowed-overhead {
 		return 0, fmt.Errorf("src is too large, final value not fit: %d", src)
 	}
+	finalVal := src + overhead
 	return int(finalVal), nil
 }