Feature: add custom DNS support (#56)

tunnel/mode.go

@@ -10,9 +10,9 @@ type Mode int
 var (
 	// ModeMapping is a mapping for Mode enum
 	ModeMapping = map[string]Mode{
-		"Global": Global,
-		"Rule":   Rule,
-		"Direct": Direct,
+		Global.String(): Global,
+		Rule.String():   Rule,
+		Direct.String(): Direct,
 	}
 )
 
@@ -34,6 +34,18 @@ func (m *Mode) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// UnmarshalYAML unserialize Mode with yaml
+func (m *Mode) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var tp string
+	unmarshal(&tp)
+	mode, exist := ModeMapping[tp]
+	if !exist {
+		return errors.New("invalid mode")
+	}
+	*m = mode
+	return nil
+}
+
 // MarshalJSON serialize Mode
 func (m Mode) MarshalJSON() ([]byte, error) {
 	return json.Marshal(m.String())