implement tcping

server/util-server.js

@@ -0,0 +1,22 @@
+const tcpp = require('tcp-ping');
+
+exports.tcping = function (hostname, port) {
+    return new Promise((resolve, reject) => {
+        tcpp.ping({
+            address: hostname,
+            port: port,
+            attempts: 1,
+        }, function(err, data) {
+
+            if (err) {
+                reject(err);
+            }
+
+            if (data.results.length >= 1 && data.results[0].err) {
+                reject(data.results[0].err);
+            }
+
+            resolve(Math.round(data.max));
+        });
+    });
+}