How to get DateTime from the internet? - c#-4.0

Question

How to get current date and time from internet or server using C#? I am trying to get time as follows:
public static DateTime GetNetworkTime (string ntpServer)
{
IPAddress[] address = Dns.GetHostEntry(ntpServer).AddressList;
if (address == null || address.Length == 0)
throw new ArgumentException("Could not resolve ip address from '" + ntpServer + "'.", "ntpServer");
IPEndPoint ep = new IPEndPoint(address[0], 123);
return GetNetworkTime(ep);
}
I am passing server IP address as netServer, but it does not work properly.

Answer 1

Here is code sample that you can use to retrieve time from NIST Internet Time Service
var client = new TcpClient("time.nist.gov", 13);
using (var streamReader = new StreamReader(client.GetStream()))
{
var response = streamReader.ReadToEnd();
var utcDateTimeString = response.Substring(7, 17);
var localDateTime = DateTime.ParseExact(utcDateTimeString, "yy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal);
}

Answer 2

Here is a quick code to get the time from the header, works without the need of port 13
public static DateTime GetNistTime()
{
var myHttpWebRequest = (HttpWebRequest)WebRequest.Create("http://www.microsoft.com");
var response = myHttpWebRequest.GetResponse();
string todaysDates = response.Headers["date"];
return DateTime.ParseExact(todaysDates,
"ddd, dd MMM yyyy HH:mm:ss 'GMT'",
CultureInfo.InvariantCulture.DateTimeFormat,
DateTimeStyles.AssumeUniversal);
}

Answer 3

Things could go wrong. All implements of the code founded above are prone to errors. Sometimes, it works and sometimes it trows a WebExpection error message.
A better implementation:
try{
using (var response =
WebRequest.Create("http://www.google.com").GetResponse())
//string todaysDates = response.Headers["date"];
return DateTime.ParseExact(response.Headers["date"],
"ddd, dd MMM yyyy HH:mm:ss 'GMT'",
CultureInfo.InvariantCulture.DateTimeFormat,
DateTimeStyles.AssumeUniversal);
}
catch (WebException)
{
return DateTime.Now; //In case something goes wrong.
}
Conclusion:
Having your web app depend on a service that provides accurate date information is critical. I have used one of the code founded here in my app and it really mess things up.

Answer 4

One more version of the same idea:
public static class InternetTime
{
public static DateTimeOffset? GetCurrentTime()
{
using (var client = new HttpClient())
{
try
{
var result = client.GetAsync("https://google.com",
HttpCompletionOption.ResponseHeadersRead).Result;
return result.Headers.Date;
}
catch
{
return null;
}
}
}
}
Here HttpCompletionOption.ResponseHeadersRead is used to prevent loading of the rest of the response, as we need only HTTP headers.
Use InternetTime.GetCurrentTime().Value.ToLocalTime() to get current local time.

Answer 5

Important: first check the avaible servers on
NIST Internet Time Servers.
public static DateTime GetServerTime()
{
var result = DateTime.Now;
// Initialize the list of NIST time servers
// http://tf.nist.gov/tf-cgi/servers.cgi
string[] servers = new string[] {
"time-c.nist.gov",
"time-d.nist.gov",
"nist1-macon.macon.ga.us",
"wolfnisttime.com",
"nist.netservicesgroup.com",
"nisttime.carsoncity.k12.mi.us",
"nist1-lnk.binary.net",
"wwv.nist.gov",
"time.nist.gov",
"utcnist.colorado.edu",
"utcnist2.colorado.edu",
"nist-time-server.eoni.com",
"nist-time-server.eoni.com"
};
Random rnd = new Random();
foreach (string server in servers.OrderBy(x => rnd.NextDouble()).Take(9))
{
try
{
// Connect to the server (at port 13) and get the response. Timeout max 1second
string serverResponse = string.Empty;
var tcpClient = new TcpClient();
if (tcpClient.ConnectAsync(server, 13).Wait(1000))
{
using (var reader = new StreamReader(tcpClient.GetStream()))
{
serverResponse = reader.ReadToEnd();
}
}
// If a response was received
if (!string.IsNullOrEmpty(serverResponse))
{
// Split the response string ("55596 11-02-14 13:54:11 00 0 0 478.1 UTC(NIST) *")
string[] tokens = serverResponse.Split(' ');
// Check the number of tokens
if (tokens.Length >= 6)
{
// Check the health status
string health = tokens[5];
if (health == "0")
{
// Get date and time parts from the server response
string[] dateParts = tokens[1].Split('-');
string[] timeParts = tokens[2].Split(':');
// Create a DateTime instance
DateTime utcDateTime = new DateTime(
Convert.ToInt32(dateParts[0]) + 2000,
Convert.ToInt32(dateParts[1]), Convert.ToInt32(dateParts[2]),
Convert.ToInt32(timeParts[0]), Convert.ToInt32(timeParts[1]),
Convert.ToInt32(timeParts[2]));
// Convert received (UTC) DateTime value to the local timezone
result = utcDateTime.ToLocalTime();
return result;
// Response successfully received; exit the loop
}
}
}
}
catch
{
// Ignore exception and try the next server
}
}
return result;
}

Answer 6

public static Nullable<DateTime> GetDateTime()
{
Nullable<DateTime> dateTime = null;
System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create("http://www.microsoft.com");
request.Method = "GET";
request.Accept = "text/html, application/xhtml+xml, */*";
request.UserAgent = "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; Trident/6.0)";
request.ContentType = "application/x-www-form-urlencoded";
request.CachePolicy = new System.Net.Cache.RequestCachePolicy(System.Net.Cache.RequestCacheLevel.NoCacheNoStore);
try
{
System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
if (response.StatusCode == System.Net.HttpStatusCode.OK)
{
string todaysDates = response.Headers["date"];
dateTime = DateTime.ParseExact(todaysDates, "ddd, dd MMM yyyy HH:mm:ss 'GMT'",
System.Globalization.CultureInfo.InvariantCulture.DateTimeFormat, System.Globalization.DateTimeStyles.AssumeUniversal);
}
}
catch
{
dateTime = null;
}
return dateTime;
}