Feature: add udp-rlybuf option

* Default UDP relay buffer size: 16KiB

engine/engine.go

@@ -129,6 +129,14 @@ func general(k *Key) error {
 		}
 		tunnel.SetUDPTimeout(k.UDPTimeout)
 	}
+
+	if k.UDPRelayBufferSize != "" {
+		size, err := units.RAMInBytes(k.UDPRelayBufferSize)
+		if err != nil {
+			return err
+		}
+		tunnel.SetUDPRelayBufferSize(int(size))
+	}
 	return nil
 }
 

engine/key.go

@@ -13,7 +13,8 @@ type Key struct {
 	TCPModerateReceiveBuffer bool          `yaml:"tcp-moderate-receive-buffer"`
 	TCPSendBufferSize        string        `yaml:"tcp-send-buffer-size"`
 	TCPReceiveBufferSize     string        `yaml:"tcp-receive-buffer-size"`
+	UDPRelayBufferSize       string        `yaml:"udp-relay-buffer-size"`
+	UDPTimeout               time.Duration `yaml:"udp-timeout"`
 	TUNPreUp                 string        `yaml:"tun-pre-up"`
 	TUNPostUp                string        `yaml:"tun-post-up"`
-	UDPTimeout               time.Duration `yaml:"udp-timeout"`
 }