实现节点下线功能，优化控制通道和数据通道的连接处理

client/report/report.go

@@ -69,5 +69,27 @@ func Online(prov, city, isp string) (id int32, host string, err error) {
 }
 
 func Offline() error {
+	var bytes, err = json.Marshal(map[string]any{
+		"name": env.Name,
+	})
+	if err != nil {
+		return err
+	}
+	var body = strings.NewReader(string(bytes))
+
+	req, err := http.NewRequest("POST", env.EndpointOffline, body)
+	if err != nil {
+		return fmt.Errorf("创建请求失败: %w", err)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("执行请求失败: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return errors.New("状态码: " + resp.Status)
+	}
+
 	return nil
 }