Add client wrappers

wrappers/packetack/client_intermediate.go

@@ -0,0 +1,85 @@
+package packetack
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net"
+
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/conntypes"
+)
+
+const clientIntermediateQuickAckLength = 0x80000000
+
+type wrapperClientIntermediate struct {
+	parent conntypes.StreamReadWriteCloser
+}
+
+func (w *wrapperClientIntermediate) Read(acks *conntypes.ConnectionAcks) (conntypes.Packet, error) {
+	buf := bytes.Buffer{}
+
+	buf.Grow(4)
+	if _, err := io.CopyN(&buf, w.parent, 4); err != nil {
+		return nil, fmt.Errorf("cannot read message length: %w", err)
+	}
+	length := binary.LittleEndian.Uint32(buf.Bytes())
+
+	if length > clientIntermediateQuickAckLength {
+		acks.Quick = true
+		length -= clientIntermediateQuickAckLength
+	}
+
+	buf.Reset()
+	buf.Grow(int(length))
+	if _, err := io.CopyN(&buf, w.parent, int64(length)); err != nil {
+		return nil, fmt.Errorf("cannot read the message: %w", err)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (w *wrapperClientIntermediate) 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
+	}
+
+	length := [4]byte{}
+	binary.LittleEndian.PutUint32(length[:], uint32(len(packet)))
+
+	if _, err := w.parent.Write(append(length[:], packet...)); err != nil {
+		return fmt.Errorf("cannot send packet: %w", err)
+	}
+	return nil
+}
+
+func (w *wrapperClientIntermediate) Close() error {
+	return w.parent.Close()
+}
+
+func (w *wrapperClientIntermediate) Conn() net.Conn {
+	return w.parent.Conn()
+}
+
+func (w *wrapperClientIntermediate) LocalAddr() *net.TCPAddr {
+	return w.parent.LocalAddr()
+}
+
+func (w *wrapperClientIntermediate) RemoteAddr() *net.TCPAddr {
+	return w.parent.RemoteAddr()
+}
+
+func (w *wrapperClientIntermediate) Logger() *zap.SugaredLogger {
+	return w.parent.Logger().Named("client-intermediate")
+}
+
+func NewClientIntermediate(parent conntypes.StreamReadWriteCloser) conntypes.PacketAckFullReadWriteCloser {
+	return &wrapperClientIntermediate{
+		parent: parent,
+	}
+}