How to Query an NTP Server using C

Question

All I need is a way to query an NTP Server using C  to get the Date Time of the NTP Server returned as either a string or as a DateTime    How is this possible in its simplest form

User · Answer

This is a optimized version of the function which removes dependency on BitConverter function and makes it compatible with NETMF   NET Micro Framework    public static DateTime GetNetworkTime         const string ntpServer    pool ntp org       var ntpData   new byte 48       ntpData 0    0x1B    LeapIndicator   0  no warning   VersionNum   3  IPv4 only   Mode   3  Client Mode       var addresses   Dns GetHostEntry ntpServer  AddressList      var ipEndPoint   new IPEndPoint addresses 0   123       var socket   new Socket AddressFamily InterNetwork  SocketType Dgram  ProtocolType Udp        socket Connect ipEndPoint       socket Send ntpData       socket Receive ntpData       socket Close         ulong intPart    ulong ntpData 40   lt  lt  24    ulong ntpData 41   lt  lt  16    ulong ntpData 42   lt  lt  8    ulong ntpData 43       ulong fractPart    ulong ntpData 44   lt  lt  24    ulong ntpData 45   lt  lt  16    ulong ntpData 46   lt  lt  8    ulong ntpData 47        var milliseconds    intPart   1000      fractPart   1000    0x100000000L       var networkDateTime    new DateTime 1900  1  1   AddMilliseconds  long milliseconds        return networkDateTime

User · Answer

I know the topic is quite old  but such tools are always handy  I ve used the resources above and created a version of NtpClient which allows asynchronously to acquire accurate time  instead of event based         lt summary gt      Represents a client which can obtain accurate time via NTP protocol       lt  summary gt  public class NtpClient       private readonly TaskCompletionSource lt DateTime gt   resultCompletionSource            lt summary gt          Creates a new instance of  lt see cref  NtpClient   gt  class           lt  summary gt      public NtpClient                  resultCompletionSource   new TaskCompletionSource lt DateTime gt                     lt summary gt          Gets accurate time using the NTP protocol with default timeout of 45 seconds           lt  summary gt           lt returns gt Network accurate  lt see cref  DateTime   gt  value  lt  returns gt      public async Task lt DateTime gt  GetNetworkTimeAsync                 return await GetNetworkTimeAsync TimeSpan FromSeconds 45                    lt summary gt          Gets accurate time using the NTP protocol with default timeout of 45 seconds           lt  summary gt           lt param name  timeoutMs  gt Operation timeout in milliseconds  lt  param gt           lt returns gt Network accurate  lt see cref  DateTime   gt  value  lt  returns gt      public async Task lt DateTime gt  GetNetworkTimeAsync int timeoutMs                return await GetNetworkTimeAsync TimeSpan FromMilliseconds timeoutMs                    lt summary gt          Gets accurate time using the NTP protocol with default timeout of 45 seconds           lt  summary gt           lt param name  timeout  gt Operation timeout  lt  param gt           lt returns gt Network accurate  lt see cref  DateTime   gt  value  lt  returns gt      public async Task lt DateTime gt  GetNetworkTimeAsync TimeSpan timeout                using  var socket   new DatagramSocket            using  var ct   new CancellationTokenSource timeout                         ct Token Register      gt   resultCompletionSource TrySetCanceled                  socket MessageReceived    OnSocketMessageReceived                The UDP port number assigned to NTP is 123             await socket ConnectAsync new HostName  pool ntp org     123                using  var writer   new DataWriter socket OutputStream                                    NTP message size is 16 bytes of the digest  RFC 2030                  var ntpBuffer   new byte 48                       Setting the Leap Indicator                      Version Number and Mode values                    LI   0  no warning                     VN   3  IPv4 only                     Mode   3  Client Mode                  ntpBuffer 0    0x1B                   writer WriteBytes ntpBuffer                   await writer StoreAsync                    var result   await  resultCompletionSource Task                  return result                                     private void OnSocketMessageReceived DatagramSocket sender  DatagramSocketMessageReceivedEventArgs args                try                       using  var reader   args GetDataReader                                  byte   response   new byte 48                   reader ReadBytes response                    resultCompletionSource TrySetResult ParseNetworkTime response                                    catch  Exception ex                         resultCompletionSource TrySetException ex                        private static DateTime ParseNetworkTime byte   rawData                  Offset to get to the  Transmit Timestamp  field  time at which the reply            departed the server for the client  in 64-bit timestamp format           const byte serverReplyTime   40             Get the seconds part         ulong intPart   BitConverter ToUInt32 rawData  serverReplyTime              Get the seconds fraction         ulong fractPart   BitConverter ToUInt32 rawData  serverReplyTime   4              Convert From big-endian to little-endian         intPart   SwapEndianness intPart           fractPart   SwapEndianness fractPart            var milliseconds    intPart   1000      fractPart   1000    0x100000000L                UTC   time         DateTime networkDateTime    new DateTime 1900  1  1  0  0  0  0  DateTimeKind Utc   AddMilliseconds  long milliseconds           return networkDateTime                stackoverflow com a 3294698 162671     private static uint SwapEndianness ulong x                return  uint    x  amp  0x000000ff   lt  lt  24                             x  amp  0x0000ff00   lt  lt  8                             x  amp  0x00ff0000   gt  gt  8                             x  amp  0xff000000   gt  gt  24              Usage   var ntp   new NtpClient    var accurateTime   await ntp GetNetworkTimeAsync TimeSpan FromSeconds 10

User · Answer

A modified version to compensate network times and calculate with DateTime-Ticks  more precise than milliseconds   public static DateTime GetNetworkTime       const string NtpServer    pool ntp org      const int DaysTo1900   1900   365   95     95   offset for leap-years etc    const long TicksPerSecond   10000000L    const long TicksPerDay   24   60   60   TicksPerSecond    const long TicksTo1900   DaysTo1900   TicksPerDay     var ntpData   new byte 48     ntpData 0    0x1B     LeapIndicator   0  no warning   VersionNum   3  IPv4 only   Mode   3  Client Mode     var addresses   Dns GetHostEntry NtpServer  AddressList    var ipEndPoint   new IPEndPoint addresses 0   123     long pingDuration   Stopwatch GetTimestamp       temp access  JIT-Compiler need some time at first call    using  var socket   new Socket AddressFamily InterNetwork  SocketType Dgram  ProtocolType Udp           socket Connect ipEndPoint       socket ReceiveTimeout   5000      socket Send ntpData       pingDuration   Stopwatch GetTimestamp       after Send-Method to reduce WinSocket API-Call time      socket Receive ntpData       pingDuration   Stopwatch GetTimestamp   - pingDuration         long pingTicks   pingDuration   TicksPerSecond   Stopwatch Frequency        optional  display response-time      Console WriteLine   0 N2  ms   new TimeSpan pingTicks  TotalMilliseconds      long intPart    long ntpData 40   lt  lt  24    long ntpData 41   lt  lt  16    long ntpData 42   lt  lt  8   ntpData 43     long fractPart    long ntpData 44   lt  lt  24    long ntpData 45   lt  lt  16    long ntpData 46   lt  lt  8   ntpData 47     long netTicks   intPart   TicksPerSecond    fractPart   TicksPerSecond  gt  gt  32      var networkDateTime   new DateTime TicksTo1900   netTicks   pingTicks   2      return networkDateTime ToLocalTime       without ToLocalTime     faster

User · Answer

The  NET Micro Framework Toolkit found in the CodePlex has an NTPClient  I have never used it myself but it looks good   There is also another example located here

User · Answer

http   www codeproject com Articles 237501 Windows-Phone-NTP-Client is going to work well for Windows Phone    Adding the relevant code       lt summary gt      Class for acquiring time via Ntp  Useful for applications in which correct world time must be used and the      clock on the device isn t  trusted        lt  summary gt  public class NtpClient            lt summary gt          Contains the time returned from the Ntp request          lt  summary gt      public class TimeReceivedEventArgs   EventArgs               public DateTime CurrentTime   get  internal set                    lt summary gt          Subscribe to this event to receive the time acquired by the NTP requests          lt  summary gt      public event EventHandler lt TimeReceivedEventArgs gt  TimeReceived       protected void OnTimeReceived DateTime time                if  TimeReceived    null                        TimeReceived this  new TimeReceivedEventArgs     CurrentTime   time                                lt summary gt          Not reallu used  I put this here so that I had a list of other NTP servers that could be used  I ll integrate this         information later and will provide method to allow some one to choose an NTP server           lt  summary gt      public string   NtpServerList   new string                  pool ntp org             asia pool ntp org            europe pool ntp org            north-america pool ntp org            oceania pool ntp org            south-america pool ntp org            time-a nist gov              string  serverName      private Socket  socket            lt summary gt          Constructor allowing an NTP server to be specified          lt  summary gt           lt param name  serverName  gt the name of the NTP server to be used lt  param gt      public NtpClient string serverName                 serverName   serverName                   lt summary gt                    lt  summary gt      public NtpClient             this  time-a nist gov                     lt summary gt          Begins the network communication required to retrieve the time from the NTP server          lt  summary gt      public void RequestTime                 byte   buffer   new byte 48           buffer 0    0x1B          for  var i   1  i  lt  buffer Length    i              buffer i    0          DnsEndPoint  endPoint   new DnsEndPoint  serverName  123             socket   new Socket AddressFamily InterNetwork  SocketType Dgram  ProtocolType Udp           SocketAsyncEventArgs sArgsConnect   new SocketAsyncEventArgs     RemoteEndPoint    endPoint            sArgsConnect Completed     o  e    gt                        if  e SocketError    SocketError Success                                SocketAsyncEventArgs sArgs   new SocketAsyncEventArgs     RemoteEndPoint    endPoint                    sArgs Completed                        new EventHandler lt SocketAsyncEventArgs gt  sArgs Completed                   sArgs SetBuffer buffer  0  buffer Length                   sArgs UserToken   buffer                   socket SendAsync sArgs                                     socket ConnectAsync sArgsConnect               void sArgs Completed object sender  SocketAsyncEventArgs e                if  e SocketError    SocketError Success                        byte   buffer    byte   e Buffer              SocketAsyncEventArgs sArgs   new SocketAsyncEventArgs                sArgs RemoteEndPoint   e RemoteEndPoint               sArgs SetBuffer buffer  0  buffer Length               sArgs Completed     o  a    gt                                if  a SocketError    SocketError Success                                        byte   timeData   a Buffer                       ulong hTime   0                      ulong lTime   0                       for  var i   40  i  lt   43    i                          hTime   hTime  lt  lt  8   buffer i                       for  var i   44  i  lt   47    i                          lTime   lTime  lt  lt  8   buffer i                       ulong milliseconds    hTime   1000    lTime   1000    0x100000000L                        TimeSpan timeSpan                           TimeSpan FromTicks  long milliseconds   TimeSpan TicksPerMillisecond                       var currentTime   new DateTime 1900  1  1    timeSpan                      OnTimeReceived currentTime                                                  socket ReceiveAsync sArgs                       Usage    public partial class MainPage   PhoneApplicationPage       private NtpClient  ntpClient      public MainPage                 InitializeComponent             ntpClient   new NtpClient             ntpClient TimeReceived    new EventHandler lt NtpClient TimeReceivedEventArgs gt   ntpClient TimeReceived              void  ntpClient TimeReceived object sender  NtpClient TimeReceivedEventArgs e                this Dispatcher BeginInvoke      gt                                                                                        txtCurrentTime Text   e CurrentTime ToLongTimeString                                                txtSystemTime Text   DateTime Now ToUniversalTime   ToLongTimeString                                                           private void UpdateTimeButton Click object sender  RoutedEventArgs e                 ntpClient RequestTime

User · Answer

Since the old accepted answer got deleted  It was a link to a Google code search results that no longer exist   I figured I could answer this question for future reference    public static DateTime GetNetworkTime           default Windows time server     const string ntpServer    time windows com           NTP message size - 16 bytes of the digest  RFC 2030      var ntpData   new byte 48          Setting the Leap Indicator  Version Number and Mode values     ntpData 0    0x1B    LI   0  no warning   VN   3  IPv4 only   Mode   3  Client Mode       var addresses   Dns GetHostEntry ntpServer  AddressList         The UDP port number assigned to NTP is 123     var ipEndPoint   new IPEndPoint addresses 0   123         NTP uses UDP      using var socket   new Socket AddressFamily InterNetwork  SocketType Dgram  ProtocolType Udp                 socket Connect ipEndPoint              Stops code hang if NTP is blocked         socket ReceiveTimeout   3000                socket Send ntpData           socket Receive ntpData           socket Close                 Offset to get to the  Transmit Timestamp  field  time at which the reply        departed the server for the client  in 64-bit timestamp format       const byte serverReplyTime   40         Get the seconds part     ulong intPart   BitConverter ToUInt32 ntpData  serverReplyTime          Get the seconds fraction     ulong fractPart   BitConverter ToUInt32 ntpData  serverReplyTime   4          Convert From big-endian to little-endian     intPart   SwapEndianness intPart       fractPart   SwapEndianness fractPart        var milliseconds    intPart   1000      fractPart   1000    0x100000000L            UTC   time     var networkDateTime    new DateTime 1900  1  1  0  0  0  DateTimeKind Utc   AddMilliseconds  long milliseconds        return networkDateTime ToLocalTime          stackoverflow com a 3294698 162671 static uint SwapEndianness ulong x        return  uint     x  amp  0x000000ff   lt  lt  24                         x  amp  0x0000ff00   lt  lt  8                         x  amp  0x00ff0000   gt  gt  8                         x  amp  0xff000000   gt  gt  24        Note  You will have to add the following namespaces  using System Net  using System Net Sockets

[c#] How to Query an NTP Server using C#?

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