C# Universal Windows 应用程序如何从互联网上获取时间

Question

我在使用 Raspberry Pi 3 运行 Windows 10 IoT 核心时遇到问题，因为系统时钟随着时间的推移往往会发生显着漂移。我决定编写一个程序，将系统时钟设置回正确的时间，设备将从互联网上获取该时间。我已经知道如何设置系统时钟，但问题是：当运行 C# Universal Windows Application on Windows 10 IoT core 时如何从互联网获取精确时间？

我之前已经完成以下操作以从 x86 和 x64 上的 windows 时间服务器获取时间：

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
    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();
}

// whosebug.com/a/3294698/162671
static uint SwapEndianness(ulong x)
{
    return (uint) (((x & 0x000000ff) << 24) +
               ((x & 0x0000ff00) << 8) +
               ((x & 0x00ff0000) >> 8) +
               ((x & 0xff000000) >> 24));
}

但它不适用于通用 windows 应用程序，因为 Dns 和其他相关类无法使用。

Answer 1

选项 1

回避问题，不使用上网时间。相反，使用像 DS1302.

这样的实时时钟集成电路

选项 2

使用 Windows 10 通用应用类通过 UDP 连接。他们使用 DatagramSocket。这是一些实现数据报套接字并从时间服务器取回响应的粗略代码。

private async void ConnectToTimeServer(object sender, RoutedEventArgs e)
{
    var socket = new DatagramSocket();
    socket.MessageReceived += SocketMessageReceived;
    await socket.ConnectAsync(new HostName("time.windows.com"), "123");

    using (var dataWriter = new DataWriter(socket.OutputStream))
    {
        var ntpData = new byte[48];
        ntpData[0] = 0x1B;
        dataWriter.WriteBytes(ntpData);
        await dataWriter.StoreAsync();
    }
}

则消息收到事件代码如下：

private void SocketMessageReceived(DatagramSocket sender, DatagramSocketMessageReceivedEventArgs args)
{
    try
    {
        using (var reader = args.GetDataReader())
        {
            byte[] response = new byte[48];
            reader.ReadBytes(response);

            YourMethodToParseNetworkTime(response);
        }
    }
    catch (Exception ex)
    {
        // Handle exceptions
    }
}

C# Universal Windows 应用程序如何从互联网上获取时间

C# Universal Windows Application How to get time from internet

c#

datetime

win-universal-app

windows-10-iot-core

windows-10-universal

选项 1

选项 2