code refactoring

upnp/utils_binary.go

@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"encoding/hex"
 	"fmt"
+	"strings"
 )
 
 // toBinary tries to convert v into a []byte.
@@ -31,3 +32,31 @@ func toBinary(v interface{}) ([]byte, error) {
 		return nil, fmt.Errorf("cannot convert type %T to binary", v)
 	}
 }
+
+// decodeBinary decodes Base64 or Hex-encoded binary strings to byte slices
+func decodeBinary(t StateVarType, val string) ([]byte, error) {
+	switch t {
+	case StateType_BinBase64:
+		data, err := base64.StdEncoding.DecodeString(val)
+		if err != nil {
+			return nil, fmt.Errorf("invalid base64: %v", err)
+		}
+		return data, nil
+
+	case StateType_BinHex:
+		// Accept even-length hex string
+		val = strings.TrimSpace(val)
+		if len(val)%2 != 0 {
+			return nil, fmt.Errorf("invalid hex: odd-length string")
+		}
+		data := make([]byte, len(val)/2)
+		_, err := hex.Decode(data, []byte(val))
+		if err != nil {
+			return nil, fmt.Errorf("invalid hex: %v", err)
+		}
+		return data, nil
+
+	default:
+		return nil, fmt.Errorf("decodeBinary: unsupported binary type %v", t)
+	}
+}