Add sub-command "-dump" to "run". (#2854)

* Add MarshalToJson().

* Add cmd arg -dump for printing out merged multiple json configs.

---------

Co-authored-by: nobody <nobody@nowhere.mars>

common/reflect/marshal.go

@@ -0,0 +1,173 @@
+package reflect
+
+import (
+	"encoding/json"
+	"reflect"
+	"slices"
+
+	cserial "github.com/xtls/xray-core/common/serial"
+)
+
+func MarshalToJson(v interface{}) (string, bool) {
+	if itf := marshalInterface(v, true); itf != nil {
+		if b, err := json.MarshalIndent(itf, "", "  "); err == nil {
+			return string(b[:]), true
+		}
+	}
+	return "", false
+}
+
+func marshalTypedMessage(v *cserial.TypedMessage, ignoreNullValue bool) interface{} {
+	tmsg, err := v.GetInstance()
+	if err != nil {
+		return nil
+	}
+	r := marshalInterface(tmsg, ignoreNullValue)
+	if msg, ok := r.(map[string]interface{}); ok {
+		msg["_TypedMessage_"] = v.Type
+	}
+	return r
+}
+
+func marshalSlice(v reflect.Value, ignoreNullValue bool) interface{} {
+	r := make([]interface{}, 0)
+	for i := 0; i < v.Len(); i++ {
+		rv := v.Index(i)
+		if rv.CanInterface() {
+			value := rv.Interface()
+			r = append(r, marshalInterface(value, ignoreNullValue))
+		}
+	}
+	return r
+}
+
+func marshalStruct(v reflect.Value, ignoreNullValue bool) interface{} {
+	r := make(map[string]interface{})
+	t := v.Type()
+	for i := 0; i < v.NumField(); i++ {
+		rv := v.Field(i)
+		if rv.CanInterface() {
+			ft := t.Field(i)
+			name := ft.Name
+			value := rv.Interface()
+			tv := marshalInterface(value, ignoreNullValue)
+			if tv != nil || !ignoreNullValue {
+				r[name] = tv
+			}
+		}
+	}
+	return r
+}
+
+func marshalMap(v reflect.Value, ignoreNullValue bool) interface{} {
+	// policy.level is map[uint32] *struct
+	kt := v.Type().Key()
+	vt := reflect.TypeOf((*interface{})(nil))
+	mt := reflect.MapOf(kt, vt)
+	r := reflect.MakeMap(mt)
+	for _, key := range v.MapKeys() {
+		rv := v.MapIndex(key)
+		if rv.CanInterface() {
+			iv := rv.Interface()
+			tv := marshalInterface(iv, ignoreNullValue)
+			if tv != nil || !ignoreNullValue {
+				r.SetMapIndex(key, reflect.ValueOf(&tv))
+			}
+		}
+	}
+	return r.Interface()
+}
+
+func marshalIString(v interface{}) (r string, ok bool) {
+	defer func() {
+		if err := recover(); err != nil {
+			r = ""
+			ok = false
+		}
+	}()
+
+	if iStringFn, ok := v.(interface{ String() string }); ok {
+		return iStringFn.String(), true
+	}
+	return "", false
+}
+
+func marshalKnownType(v interface{}, ignoreNullValue bool) (interface{}, bool) {
+	switch ty := v.(type) {
+	case cserial.TypedMessage:
+		return marshalTypedMessage(&ty, ignoreNullValue), true
+	case *cserial.TypedMessage:
+		return marshalTypedMessage(ty, ignoreNullValue), true
+	case map[string]json.RawMessage:
+		return ty, true
+	case []json.RawMessage:
+		return ty, true
+	case *json.RawMessage:
+		return ty, true
+	case json.RawMessage:
+		return ty, true
+	default:
+		return nil, false
+	}
+}
+
+var valueKinds = []reflect.Kind{
+	reflect.Bool,
+	reflect.Int,
+	reflect.Int8,
+	reflect.Int16,
+	reflect.Int32,
+	reflect.Int64,
+	reflect.Uint,
+	reflect.Uint8,
+	reflect.Uint16,
+	reflect.Uint32,
+	reflect.Uint64,
+	reflect.Uintptr,
+	reflect.Float32,
+	reflect.Float64,
+	reflect.Complex64,
+	reflect.Complex128,
+	reflect.String,
+}
+
+func isValueKind(kind reflect.Kind) bool {
+	return slices.Contains(valueKinds, kind)
+}
+
+func marshalInterface(v interface{}, ignoreNullValue bool) interface{} {
+
+	if r, ok := marshalKnownType(v, ignoreNullValue); ok {
+		return r
+	}
+
+	rv := reflect.ValueOf(v)
+	if rv.Kind() == reflect.Ptr {
+		rv = rv.Elem()
+	}
+	k := rv.Kind()
+	if k == reflect.Invalid {
+		return nil
+	}
+	if isValueKind(k) {
+		return v
+	}
+
+	switch k {
+	case reflect.Struct:
+		return marshalStruct(rv, ignoreNullValue)
+	case reflect.Slice:
+		return marshalSlice(rv, ignoreNullValue)
+	case reflect.Array:
+		return marshalSlice(rv, ignoreNullValue)
+	case reflect.Map:
+		return marshalMap(rv, ignoreNullValue)
+	default:
+		break
+	}
+
+	if str, ok := marshalIString(v); ok {
+		return str
+	}
+	return nil
+}