diff --git a/next/assets/assets.go b/next/assets/assets.go
index e0d0f8c..4f048d4 100644
--- a/next/assets/assets.go
+++ b/next/assets/assets.go
@@ -3,8 +3,35 @@ package assets
 import (
 	"XProxy/next/logger"
 	"os"
+	"time"
 )
 
+// saveAsset is used to write to a local file and specify its last modify
+// time. If the file exists, it will be replaced.
+func saveAsset(file string, content []byte, date *time.Time) error {
+	fp, err := os.OpenFile(file, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		logger.Errorf("Failed to open file `%s` -> %v", file, err)
+		return err
+	}
+	defer fp.Close()
+
+	_, err = fp.Write(content)
+	if err != nil {
+		logger.Errorf("Failed to save file `%s` -> %v", file, err)
+		return err
+	}
+
+	if date != nil { // change local file last modify time
+		if err := os.Chtimes(file, *date, *date); err != nil {
+			logger.Warnf("Failed to change asset modification time")
+		} else {
+			logger.Debugf("Change `%s` modification time to `%v`", file, date)
+		}
+	}
+	return nil
+}
+
 // updateRemoteAsset will download remote asset via the optional proxy and
 // save them locally. Local files will be overwritten if they exist.
 func updateRemoteAsset(file string, url string, proxy string) error {
@@ -14,38 +41,50 @@ func updateRemoteAsset(file string, url string, proxy string) error {
 		logger.Errorf("Failed to download remote asset `%s`", url)
 		return err
 	}
-	asset, err = tryExtract(asset)
+	if asset, err = tryExtract(asset); err != nil {
+		return err
+	}
+	if err := saveAsset(file, asset, date); err != nil {
+		return err
+	}
+	logger.Infof("Successfully obtained remote asset `%s`", file)
+	return nil
+}
 
-	fp, err := os.OpenFile(file, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+// updateLocalAsset will extract local asset and save them locally. If the
+// local file already exists, it will be skipped.
+func updateLocalAsset(file string, src string) error {
+	_, err := os.Stat(file)
+	if err == nil {
+		logger.Debugf("Local asset `%s` already exist", file)
+		return nil // skip local asset extract
+	}
+
+	var date = time.Now()
+	if stat, err := os.Stat(src); err == nil {
+		date = stat.ModTime() // using last modify time of src file
+	}
+
+	logger.Debugf("Start extracting local asset `%s`", file)
+	asset, err := os.ReadFile(src)
 	if err != nil {
-		logger.Errorf("Failed to open file `%s` -> %v", file, err)
+		logger.Errorf("Failed to read local asset -> %v", err)
 		return err
 	}
-	defer fp.Close()
-	_, err = fp.Write(asset)
-	if err != nil {
-		logger.Errorf("Failed to save file `%s` -> %v", file, err)
+	if asset, err = tryExtract(asset); err != nil {
 		return err
 	}
-
-	if err := os.Chtimes(file, *date, *date); err != nil {
-		logger.Warnf("Failed to change asset modification time")
-	} else {
-		logger.Debugf("Change `%s` modification time to `%v`", file, date)
+	if err := saveAsset(file, asset, &date); err != nil {
+		return err
 	}
-	logger.Infof("Successfully obtained remote asset `%s`", file)
+	logger.Infof("Successfully extracted local asset `%s`", file)
 	return nil
 }
 
 func Demo() {
-	//raw, t, _ := download("https://github.com/Loyalsoldier/v2ray-rules-dat/releases/download/202309082208/geosite.dat", "")
-	//raw, t, _ := download("https://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat", "")
-	//raw, t, _ := download("https://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat", "socks5://192.168.2.2:1084")
-	//raw, t, _ := download("https://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat.xz", "")
-	//logger.Infof("%v", t)
-	//ret, _ := tryExtract(raw)
-	//logger.Debugf("content size -> %d", len(ret))
-
-	updateRemoteAsset("geosite.dat", "http://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat.xz", "")
+
+	//updateRemoteAsset("geosite.dat", "http://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat.xz", "")
+	//updateRemoteAsset("geosite.dat", "http://cdn.dnomd343.top/v2ray-rules-dat/geosite.dat.xz", "socks5://192.168.2.2:1084")
+	updateLocalAsset("geosite.dat", "geosite.dat.xz")
 
 }
diff --git a/next/assets/remote.go b/next/assets/remote.go
index 4022c5e..855a021 100644
--- a/next/assets/remote.go
+++ b/next/assets/remote.go
@@ -90,6 +90,7 @@ func createClient(remoteUrl string, proxyUrl string) (http.Client, error) {
 	}, nil
 }
 
+// doRequest initiates http request and allows retries.
 func doRequest(client http.Client, req *http.Request) (*http.Response, error) {
 	maxRetry := retry.Attempts(DownloadRetry)
 	maxDelay := retry.MaxDelay(DownloadTimeout * time.Second)