header-custom finalmask: Add UDP standalone handshake mode (#5945)

175502d807

infra/conf/transport_internet.go

@@ -1657,11 +1657,18 @@ func buildCustomTransformArg(arg CustomTransformArg) (*custom.ExprArg, error) {
 }
 
 type HeaderCustomUDP struct {
+	Mode   string    `json:"mode"`
 	Client []UDPItem `json:"client"`
 	Server []UDPItem `json:"server"`
 }
 
 func (c *HeaderCustomUDP) Build() (proto.Message, error) {
+	switch c.Mode {
+	case "", "prefix", "standalone":
+	default:
+		return nil, errors.New("unknown udp mode")
+	}
+
 	for _, item := range c.Client {
 		if err := validateCustomItemSpec(item.Capture, item.Packet, item.Rand, item.Reuse, item.Transform); err != nil {
 			return nil, err
@@ -1730,6 +1737,7 @@ func (c *HeaderCustomUDP) Build() (proto.Message, error) {
 	return &custom.UDPConfig{
 		Client: client,
 		Server: server,
+		Mode:   c.Mode,
 	}, nil
 }
 

infra/conf/transport_test.go

@@ -191,10 +191,12 @@ func TestHeaderCustomUDPBuild(t *testing.T) {
 					{
 						"reuse": "txid"
 					}
-				]
+				],
+				"mode": "standalone"
 			}`,
 			Parser: parser,
 			Output: &finalmaskcustom.UDPConfig{
+				Mode: "standalone",
 				Client: []*finalmaskcustom.UDPItem{
 					{
 						RandMax: 255,