feat(go): Port full Ananta private server to Go architecture

pkg/protocol/frame.go

@@ -0,0 +1,132 @@
+package protocol
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+
+	"ananta-ps/pkg/crypto/chacha8"
+)
+
+type Frame struct {
+	Mode    byte
+	Payload []byte
+}
+
+func ReadFrame(r io.Reader, cryptor *chacha8.UxChaCha8) (*Frame, error) {
+	head := make([]byte, 5)
+	if _, err := io.ReadFull(r, head); err != nil {
+		return nil, err
+	}
+
+	if cryptor != nil {
+		cryptor.XorInPlace(head)
+	}
+
+	payloadLength := int(binary.LittleEndian.Uint32(head[0:4]))
+	if payloadLength < 0 || payloadLength > 16*1024*1024 {
+		return nil, errors.New("invalid frame payload length after decrypt")
+	}
+
+	payload := make([]byte, payloadLength)
+	if payloadLength > 0 {
+		if _, err := io.ReadFull(r, payload); err != nil {
+			return nil, err
+		}
+		if cryptor != nil {
+			cryptor.XorInPlace(payload)
+		}
+	}
+
+	return &Frame{
+		Mode:    head[4],
+		Payload: payload,
+	}, nil
+}
+
+func WriteFrame(w io.Writer, mode byte, payload []byte, cryptor *chacha8.UxChaCha8) error {
+	buf := make([]byte, 5+len(payload))
+	binary.LittleEndian.PutUint32(buf[0:4], uint32(len(payload)))
+	buf[4] = mode
+	copy(buf[5:], payload)
+
+	if cryptor != nil {
+		cryptor.XorInPlace(buf)
+	}
+
+	_, err := w.Write(buf)
+	return err
+}
+
+func ParseRpcPacket(payload []byte) RpcPacket {
+	if len(payload) < 5 {
+		return RpcPacket{Kind: PacketKindUnknown, Body: payload}
+	}
+
+	tag := payload[0]
+	methodID := binary.LittleEndian.Uint32(payload[1:5])
+
+	switch tag {
+	case 0x03: // Notify
+		return RpcPacket{
+			Kind:     PacketKindNotify,
+			MethodID: methodID,
+			Body:     payload[5:],
+		}
+	case 0x01: // Invoke
+		if len(payload) >= 9 {
+			invokeID := int32(binary.LittleEndian.Uint32(payload[5:9]))
+			return RpcPacket{
+				Kind:     PacketKindInvoke,
+				MethodID: methodID,
+				InvokeID: invokeID,
+				Body:     payload[9:],
+			}
+		}
+	case 0x02: // Return
+		if len(payload) >= 13 {
+			invokeID := int32(binary.LittleEndian.Uint32(payload[5:9]))
+			errCode := int32(binary.LittleEndian.Uint32(payload[9:13]))
+			return RpcPacket{
+				Kind:     PacketKindReturn,
+				MethodID: methodID,
+				InvokeID: invokeID,
+				Error:    errCode,
+				Body:     payload[13:],
+			}
+		}
+	}
+
+	return RpcPacket{
+		Kind:     PacketKindUnknown,
+		MethodID: methodID,
+		Body:     payload,
+	}
+}
+
+func BuildNotify(methodID uint32, body []byte) []byte {
+	buf := make([]byte, 5+len(body))
+	buf[0] = 0x03
+	binary.LittleEndian.PutUint32(buf[1:5], methodID)
+	copy(buf[5:], body)
+	return buf
+}
+
+func BuildInvoke(methodID uint32, invokeID int32, body []byte) []byte {
+	buf := make([]byte, 9+len(body))
+	buf[0] = 0x01
+	binary.LittleEndian.PutUint32(buf[1:5], methodID)
+	binary.LittleEndian.PutUint32(buf[5:9], uint32(invokeID))
+	copy(buf[9:], body)
+	return buf
+}
+
+func BuildReturn(methodID uint32, invokeID int32, errCode int32, body []byte) []byte {
+	buf := make([]byte, 13+len(body))
+	buf[0] = 0x02
+	binary.LittleEndian.PutUint32(buf[1:5], methodID)
+	binary.LittleEndian.PutUint32(buf[5:9], uint32(invokeID))
+	binary.LittleEndian.PutUint32(buf[9:13], uint32(errCode))
+	copy(buf[13:], body)
+	return buf
+}