Add client wrappers

wrappers/packetack/client_intermediate_secure.go

@@ -0,0 +1,54 @@
+package packetack
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"math/rand"
+
+	"github.com/9seconds/mtg/conntypes"
+)
+
+type wrapperClientIntermediateSecure struct {
+	wrapperClientIntermediate
+}
+
+func (w *wrapperClientIntermediateSecure) Read(acks *conntypes.ConnectionAcks) (conntypes.Packet, error) {
+	data, err := w.wrapperClientIntermediate.Read(acks)
+	if err != nil {
+		return nil, err
+	}
+	length := len(data) - (len(data) % 4)
+
+	return data[:length], nil
+}
+
+func (w *wrapperClientIntermediateSecure) Write(packet conntypes.Packet, acks *conntypes.ConnectionAcks) error {
+	if acks.Simple {
+		if _, err := w.parent.Write(packet); err != nil {
+			return fmt.Errorf("cannot send simpleacked packet: %w", err)
+		}
+		return nil
+	}
+
+	buf := bytes.Buffer{}
+	paddingLength := rand.Intn(4)
+	buf.Grow(4 + len(packet) + paddingLength)
+
+	binary.Write(&buf, binary.LittleEndian, uint32(len(packet)+paddingLength))
+	buf.Write(packet)
+	buf.Write(make([]byte, paddingLength))
+
+	if _, err := w.parent.Write(buf.Bytes()); err != nil {
+		return fmt.Errorf("cannot send packet: %w", err)
+	}
+	return nil
+}
+
+func NewClientIntermediateSecure(parent conntypes.StreamReadWriteCloser) conntypes.PacketAckFullReadWriteCloser {
+	return &wrapperClientIntermediateSecure{
+		wrapperClientIntermediate: wrapperClientIntermediate{
+			parent: parent,
+		},
+	}
+}