Add libbox API to detect tun inbounds

experimental/libbox/config.go

@@ -6,6 +6,7 @@ import (
 	"net/netip"
 	"os"
 	"reflect"
+	"slices"
 
 	box "github.com/sagernet/sing-box"
 	"github.com/sagernet/sing-box/adapter"
@@ -269,3 +270,13 @@ func FormatConfig(configContent string) (*StringBox, error) {
 	}
 	return wrapString(buffer.String()), nil
 }
+
+func HasTunInbound(configContent string) (bool, error) {
+	options, err := parseConfig(baseContext(nil), configContent)
+	if err != nil {
+		return false, err
+	}
+	return slices.ContainsFunc(options.Inbounds, func(inbound option.Inbound) bool {
+		return inbound.Type == C.TypeTun
+	}), nil
+}