Allow TUN inbound to omit port configuration

Co-authored-by: RPRX <[email protected]>

infra/conf/xray.go

@@ -130,7 +130,10 @@ type InboundDetourConfig struct {
 func (c *InboundDetourConfig) Build() (*core.InboundHandlerConfig, error) {
 	receiverSettings := &proxyman.ReceiverConfig{}
 
-	if c.ListenOn == nil {
+	// TUN inbound doesn't need port configuration as it uses network interface instead
+	if c.Protocol == "tun" {
+		// Skip port validation for TUN
+	} else if c.ListenOn == nil {
 		// Listen on anyip, must set PortList
 		if c.PortList == nil {
 			return nil, errors.New("Listen on AnyIP but no Port(s) set in InboundDetour.")