Add packet padding container for packet length shaping

common/packetPaddingContainer/container.go

@@ -0,0 +1,47 @@
+package packetPaddingContainer
+
+import "encoding/binary"
+
+func New() PacketPaddingContainer {
+	return packetPaddingContainer{}
+}
+
+type packetPaddingContainer struct {
+}
+
+func (c packetPaddingContainer) Pack(data_OWNERSHIP_RELINQUISHED []byte, padding int) []byte {
+	data := append(data_OWNERSHIP_RELINQUISHED, make([]byte, padding)...)
+	data_length := len(data_OWNERSHIP_RELINQUISHED)
+	data = append(data, byte(data_length>>8), byte(data_length))
+	return data
+}
+
+func (c packetPaddingContainer) Pad(padding int) []byte {
+	if assertPaddingLengthIsNotNegative := padding < 0; assertPaddingLengthIsNotNegative {
+		return nil
+	}
+	switch padding {
+	case 0:
+		return []byte{}
+	case 1:
+		return []byte{0}
+	case 2:
+		return []byte{0, 0}
+	default:
+		return append(make([]byte, padding-2), byte(padding>>8), byte(padding))
+	}
+
+}
+
+func (c packetPaddingContainer) Unpack(wrappedData_OWNERSHIP_RELINQUISHED []byte) ([]byte, int) {
+	if len(wrappedData_OWNERSHIP_RELINQUISHED) < 2 {
+		return nil, len(wrappedData_OWNERSHIP_RELINQUISHED)
+	}
+	wrappedData_tail := wrappedData_OWNERSHIP_RELINQUISHED[len(wrappedData_OWNERSHIP_RELINQUISHED)-2:]
+	dataLength := int(binary.BigEndian.Uint16(wrappedData_tail))
+	paddingLength := len(wrappedData_OWNERSHIP_RELINQUISHED) - dataLength - 2
+	if paddingLength < 0 {
+		return nil, paddingLength
+	}
+	return wrappedData_OWNERSHIP_RELINQUISHED[:dataLength], paddingLength
+}