NtpTimer.cs

//This code is for ROS# message header timestamp
//You also need GuerrillaNtp.dll in plugin directory  (https://www.nuget.org/packages/GuerrillaNtp/ )
//
//Usage: just attach some gameobject.
//       and configure the NTP server host/port on unity editor. (!!NEVER!! Point out Public NTP server)
//       This will override timestamp header (in StandardHeaderExtensions.cs)
//
// Here is sample code of NTP server which run as ros node.
// https://gist.github.com/akirayou/6488e2834bc26226d511d4bee4fbcb61
//
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

using System;
using System.Net;
using System.Net.Sockets;
using GuerrillaNtp;

using System.Threading.Tasks;

namespace RosSharp.RosBridgeClient
{
    /// <summary>
    /// Use NTP for Message header
    /// To use this. Just attach to Any object object in Unity
    /// and configure host and port.
    /// </summary>
    public class NtpTimer : Timer
    {
        /// <summary>
        /// NTP server host name
        /// </summary>
        public string Host = "10.0.1.108";
        /// <summary>
        /// NTP port (default:123)
        /// </summary>
        public Int16 Port = 123;
        /// <summary>
        /// NTP request time span (sec)
        /// </summary>
        public float NtpSpan = 10;
        /// <summary>
        /// Just for Application (not for RosBridge) Check time sync was done 
        /// </summary>
        /// <returns></returns>
        public bool Synced() { return synced; } 
        public TimeSpan Offset() { return offset; }

        private TimeSpan offset;
        private bool synced = false;

        public static DateTime UNIX_EPOCH = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
        public override Messages.Standard.Time Now()
        {
            TimeSpan unixEpoch = DateTime.Now.ToUniversalTime() - UNIX_EPOCH + offset;
            double ds = unixEpoch.TotalMilliseconds;
            uint sec = (uint)(ds / 1000);
            RosSharp.RosBridgeClient.Messages.Standard.Time ret = new RosSharp.RosBridgeClient.Messages.Standard.Time
            {
                secs = sec,
                nsecs = (uint)((ds / 1000 - sec) * 1e+9)
            };
            return ret;
        }

        new void Awake()
        {
            //Override time stamp header
            HeaderExtensions.Timer = this; //If you want to override manually ,comment out this
            NtpClient ntp;
            ntp = new NtpClient(Dns.GetHostEntry(Host).AddressList[0], Port);
            Debug.Log("Use NTP time for Ros header timestamp");

        }

        // Update is called once per frame
        private float timeElapsed=1e+10f;
        async void Update()
        {
            timeElapsed += Time.deltaTime;
            if (timeElapsed < NtpSpan) return;
            timeElapsed = 0;
            TimeSpan tmp;
            bool isOk = false;
            await Task.Run(() =>
            {
                try
                {
                    NtpClient ntp;
                    ntp = new NtpClient(Dns.GetHostEntry(Host).AddressList[0], Port);
                    tmp = ntp.GetCorrectionOffset();
                    isOk = true;
                }
                catch (Exception e)
                {
                    Debug.LogError("Ntp error:" + e.ToString());
                    isOk = false;
                }
            });
            if (!isOk) return;
            if (!synced)
            {
                offset = tmp;
                synced = true;
                Debug.Log("NtpTime is started  offset is "+offset.ToString());
            }
            else
            {
                offset = TimeSpan.FromSeconds(0.9 * offset.TotalSeconds + 0.1 * tmp.TotalSeconds);
            }
        }
    }
}