Nas*_*ine 146
由于旧的已接受的答案被删除(这是一个不再存在的Google代码搜索结果的链接),我想我可以回答这个问题以供将来参考:
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 & 0x000000ff) << 24) +
((x & 0x0000ff00) << 8) +
((x & 0x00ff0000) >> 8) +
((x & 0xff000000) >> 24));
}
注意:您必须添加以下命名空间
using System.Net;
using System.Net.Sockets;
小智 33
这是该函数的优化版本,它消除了对BitConverter函数的依赖,并使其与NETMF(.NET Micro Framework)兼容
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] << 24 | (ulong)ntpData[41] << 16 | (ulong)ntpData[42] << 8 | (ulong)ntpData[43];
ulong fractPart = (ulong)ntpData[44] << 24 | (ulong)ntpData[45] << 16 | (ulong)ntpData[46] << 8 | (ulong)ntpData[47];
var milliseconds = (intPart * 1000) + ((fractPart * 1000) / 0x100000000L);
var networkDateTime = (new DateTime(1900, 1, 1)).AddMilliseconds((long)milliseconds);
return networkDateTime;
}
我知道这个主题很老了,但这些工具总是很方便.我已经使用了上面的资源并创建了一个NtpClient版本,它允许异步获取准确的时间,而不是基于事件.
/// <summary>
/// Represents a client which can obtain accurate time via NTP protocol.
/// </summary>
public class NtpClient
{
private readonly TaskCompletionSource<DateTime> _resultCompletionSource;
/// <summary>
/// Creates a new instance of <see cref="NtpClient"/> class.
/// </summary>
public NtpClient()
{
_resultCompletionSource = new TaskCompletionSource<DateTime>();
}
/// <summary>
/// Gets accurate time using the NTP protocol with default timeout of 45 seconds.
/// </summary>
/// <returns>Network accurate <see cref="DateTime"/> value.</returns>
public async Task<DateTime> GetNetworkTimeAsync()
{
return await GetNetworkTimeAsync(TimeSpan.FromSeconds(45));
}
/// <summary>
/// Gets accurate time using the NTP protocol with default timeout of 45 seconds.
/// </summary>
/// <param name="timeoutMs">Operation timeout in milliseconds.</param>
/// <returns>Network accurate <see cref="DateTime"/> value.</returns>
public async Task<DateTime> GetNetworkTimeAsync(int timeoutMs)
{
return await GetNetworkTimeAsync(TimeSpan.FromMilliseconds(timeoutMs));
}
/// <summary>
/// Gets accurate time using the NTP protocol with default timeout of 45 seconds.
/// </summary>
/// <param name="timeout">Operation timeout.</param>
/// <returns>Network accurate <see cref="DateTime"/> value.</returns>
public async Task<DateTime> GetNetworkTimeAsync(TimeSpan timeout)
{
using (var socket = new DatagramSocket())
using (var ct = new CancellationTokenSource(timeout))
{
ct.Token.Register(() => _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 & 0x000000ff) << 24) +
((x & 0x0000ff00) << 8) +
((x & 0x00ff0000) >> 8) +
((x & 0xff000000) >> 24));
}
}
用法:
var ntp = new NtpClient();
var accurateTime = await ntp.GetNetworkTimeAsync(TimeSpan.FromSeconds(10));
修改版本以补偿网络时间并使用DateTime-Ticks进行计算（比毫秒更精确）
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] << 24 | (long)ntpData[41] << 16 | (long)ntpData[42] << 8 | ntpData[43];
long fractPart = (long)ntpData[44] << 24 | (long)ntpData[45] << 16 | (long)ntpData[46] << 8 | ntpData[47];
long netTicks = intPart * TicksPerSecond + (fractPart * TicksPerSecond >> 32);
var networkDateTime = new DateTime(TicksTo1900 + netTicks + pingTicks / 2);
return networkDateTime.ToLocalTime(); // without ToLocalTime() = faster
}