add bind for relay

pkg/handler/relay/metadata.go

@@ -12,13 +12,17 @@ type metadata struct {
 	authenticator auth.Authenticator
 	readTimeout   time.Duration
 	retryCount    int
+	enableBind    bool
+	udpBufferSize int
 }
 
 func (h *relayHandler) parseMetadata(md md.Metadata) (err error) {
 	const (
-		users       = "users"
-		readTimeout = "readTimeout"
-		retryCount  = "retry"
+		users         = "users"
+		readTimeout   = "readTimeout"
+		retryCount    = "retry"
+		enableBind    = "bind"
+		udpBufferSize = "udpBufferSize"
 	)
 
 	if v, _ := md.Get(users).([]interface{}); len(v) > 0 {
@@ -37,5 +41,17 @@ func (h *relayHandler) parseMetadata(md md.Metadata) (err error) {
 	}
 	h.md.readTimeout = md.GetDuration(readTimeout)
 	h.md.retryCount = md.GetInt(retryCount)
+	h.md.enableBind = md.GetBool(enableBind)
+	h.md.udpBufferSize = md.GetInt(udpBufferSize)
+	if h.md.udpBufferSize > 0 {
+		if h.md.udpBufferSize < 512 {
+			h.md.udpBufferSize = 512 // min buffer size
+		}
+		if h.md.udpBufferSize > 65*1024 {
+			h.md.udpBufferSize = 65 * 1024 // max buffer size
+		}
+	} else {
+		h.md.udpBufferSize = 1024 // default buffer size
+	}
 	return
 }