add proto reflection based configure file parsing rule

common/protoext/extensions.proto

@@ -25,4 +25,9 @@ message FieldOpt{
   repeated string any_wants = 1;
   repeated string allowed_values = 2;
   repeated string allowed_value_types = 3;
+
+  // convert_time_read_file_into read a file into another field, and clear this field during input parsing
+  string convert_time_read_file_into = 4;
+  // forbidden marks a boolean to be inaccessible to user
+  bool forbidden = 5;
 }

infra/conf/protofilter/filter.go

@@ -0,0 +1,90 @@
+package protofilter
+
+import (
+	"github.com/v2fly/v2ray-core/v4/common/platform/filesystem"
+	"github.com/v2fly/v2ray-core/v4/common/protoext"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+//go:generate go run github.com/v2fly/v2ray-core/v4/common/errors/errorgen
+
+func FilterProtoConfig(config proto.Message) error {
+	messageProtoReflect := config.ProtoReflect()
+	return filterMessage(messageProtoReflect)
+}
+
+func filterMessage(message protoreflect.Message) error {
+	var err error
+	type fileRead struct {
+		filename string
+		field    string
+	}
+	var fileReadingQueue []fileRead
+	message.Range(func(descriptor protoreflect.FieldDescriptor, value protoreflect.Value) bool {
+		v2extension, ferr := protoext.GetFieldOptions(descriptor)
+		if ferr != nil {
+			if v2extension.Forbidden {
+				if value.Bool() {
+					err = newError("a forbidden value is set ", descriptor.FullName())
+					return false
+				}
+			}
+
+			if v2extension.ConvertTimeReadFileInto != "" {
+				fileReadingQueue = append(fileReadingQueue, fileRead{
+					filename: value.String(),
+					field:    v2extension.ConvertTimeReadFileInto,
+				})
+			}
+		}
+
+		switch descriptor.Kind() {
+		case protoreflect.MessageKind:
+			if descriptor.IsMap() {
+				err = filterMap(value.Map())
+				break
+			}
+			if descriptor.IsList() {
+				err = filterList(value.List())
+				break
+			}
+			err = filterMessage(value.Message())
+		}
+		return true
+	})
+
+	for _, v := range fileReadingQueue {
+		file, err := filesystem.ReadFile(v.filename)
+		if err != nil {
+			return newError("unable to read file").Base(err)
+		}
+		field := message.Descriptor().Fields().ByTextName(v.field)
+		message.Set(field, protoreflect.ValueOf(file))
+	}
+	return nil
+}
+
+func filterMap(mapValue protoreflect.Map) error {
+	var err error
+	mapValue.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
+		err = filterMessage(value.Message())
+		if err != nil {
+			return false
+		}
+		return true
+	})
+	return err
+}
+
+func filterList(listValue protoreflect.List) error {
+	var err error
+	size := listValue.Len()
+	for i := 0; i < size; i++ {
+		err = filterMessage(listValue.Get(i).Message())
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}