Add NTP stratum info

README.md

@@ -5,6 +5,8 @@ Pure Javascript implementation of the NTP Client Protocol
 ## Getting Started
 Install the module with: `npm install ntp-client`
 
+## Examples
+### Get just the time
 ```javascript
 var ntpClient = require('ntp-client');
 
@@ -19,9 +21,28 @@ ntpClient.getNetworkTime("pool.ntp.org", 123, function(err, date) {
 });
 ```
 
+### Get the time and the server's stratum
+Get the server's startum:
+```javascript
+var ntpClient = require('ntp-client');
+
+ntpClient.getNetworkTime("pool.ntp.org", 123, function(err, date, stratum) {
+    if(err) {
+        console.error(err);
+        return;
+    }
+
+    console.log("Current time : ");
+    console.log(date); // Mon Jul 08 2013 21:31:31 GMT+0200 (Paris, Madrid (heure d’été))
+    console.log("Current stratum : "); 
+    console.log(stratum); // 3
+});
+```
+
 ## Contributors
  * Clément Bourgeois (https://github.com/moonpyk)
  * Callan Bryant (https://github.com/naggie)
+ * SomKen (https://github.com/somken)
 
 ## License
 Copyright (c) 2014 Clément Bourgeois

lib/ntp-client.js

@@ -21,11 +21,10 @@
     exports.ntpReplyTimeout = 10000;
 
     /**
-     * Fetches the current NTP Time from the given server and port.
+     * Fetches the current NTP Time from the given server and port, including stratum.
      * @param {string} server IP/Hostname of the remote NTP Server
      * @param {number} port Remote NTP Server port number
-     * @param {function(Object, Date)} callback(err, date) Async callback for
-     * the result date or eventually error.
+     * @param {function(Object, Date, number)} callback(err, date, stratum) Async callback for the result date, stratum, or error.
      */
     exports.getNetworkTime = function (server, port, callback) {
         if (callback === null || typeof callback !== "function") {
@@ -36,7 +35,7 @@
         port = port || exports.defaultNtpPort;
 
         var client = dgram.createSocket("udp4"),
-            ntpData = new Buffer(48);
+            ntpData = Buffer.alloc(48);
 
         // RFC 2030 -> LI = 0 (no warning, 2 bits), VN = 3 (IPv4 only, 3 bits), Mode = 3 (Client Mode, 3 bits) -> 1 byte
         // -> rtol(LI, 6) ^ rotl(VN, 3) ^ rotl(Mode, 0)
@@ -49,7 +48,7 @@
 
         var timeout = setTimeout(function () {
             client.close();
-            callback("Timeout waiting for NTP response.", null);
+            callback("Timeout waiting for NTP response.", null, null);
         }, exports.ntpReplyTimeout);
 
         // Some errors can happen before/after send() or cause send() to was impossible.
@@ -63,7 +62,7 @@
                 return;
             }
 
-            callback(err, null);
+            callback(err, null, null);
             errorFired = true;
 
             clearTimeout(timeout);
@@ -75,7 +74,7 @@
                     return;
                 }
                 clearTimeout(timeout);
-                callback(err, null);
+                callback(err, null, null);
                 errorFired = true;
                 client.close();
                 return;
@@ -85,8 +84,11 @@
                 clearTimeout(timeout);
                 client.close();
 
+                // Extract Stratum (byte 1)
+                var stratum = msg[1];
+
                 // Offset to get to the "Transmit Timestamp" field (time at which the reply
-                // departed the server for the client, in 64-bit timestamp format."
+                // departed the server for the client, in 64-bit timestamp format)
                 var offsetTransmitTime = 40,
                     intpart = 0,
                     fractpart = 0;
@@ -107,7 +109,8 @@
                 var date = new Date("Jan 01 1900 GMT");
                 date.setUTCMilliseconds(date.getUTCMilliseconds() + milliseconds);
 
-                callback(null, date);
+                // Return date and stratum in callback
+                callback(null, date, stratum);
             });
         });
     };
@@ -116,13 +119,14 @@
         exports.getNetworkTime(
             exports.defaultNtpServer,
             exports.defaultNtpPort,
-            function (err, date) {
+            function (err, date, stratum) {
                 if (err) {
                     console.error(err);
                     return;
                 }
 
-                console.log(date);
+                console.log('NTP Date:', date);
+                console.log('Stratum:', stratum);
             });
     };
 }(exports));

package.json

@@ -1,7 +1,7 @@
 {
     "name": "ntp-client",
     "description": "Pure Javascript implementation of the NTP Client Protocol",
-    "version": "0.5.3",
+    "version": "0.5.4",
     "homepage": "https://github.com/moonpyk/node-ntp-client",
     "author": {
         "name": "Clément Bourgeois",

test/ntp-client_test.js

@@ -61,6 +61,26 @@
 
     };
 
+    exports.validNTPServerStratum = function (test) {
+        ntpClient.getNetworkTime(ntpClient.defaultNtpServer, ntpClient.defaultNtpPort, function (err, date, stratum) {
+            console.log();
+            console.log("System reported : %s", new Date());
+
+            test.ok(err === null);
+            test.ok(date !== null);
+            test.ok(stratum !== null);
+            test.ok(stratum >= 0);
+
+            console.log("NTP Reported : %s", date);
+            console.log("Stratum Reported : %s", stratum);
+
+            // I won't test returned datetime against the system datetime
+            // this is the whole purpose of NTP : putting clocks in sync.
+            test.done();
+        });
+
+    };    
+
     exports.invalidNTPServer = function (test) {
         // I'm pretty sure there is no NTP Server listening at google.com
         ntpClient.getNetworkTime("google.com", 123, function (err, date) {