iot-light.cs

using System;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace udptest
{
	class Program
	{
		static void Main(string[] args)
		{
			SendColorChangeBytes("535a3030000000000023000000000000000000000000000000001d000000000000000000041d0602ff01c10a00", 0);
			SendColorChangeBytes("535a3030000000000023000000000000000000000000000000001800000000000000000004180602ff04c40600", 0);
			SendColorChangeBytes("535a3030000000000023000000000000000000000000000000001200000000000000000004120602ff06bd0280", 0);
		}

		private static void SendColorChangeBytes(string requestDataString, int tries)
		{
			using (var client = new UdpClient { EnableBroadcast = true })
			{
				var requestData = ToByteArray(requestDataString);

				var broadcast = new IPEndPoint(IPAddress.Parse("192.168.10.255"), 8900);

				client.Send(requestData, requestData.Length, broadcast);

				var serverReceiveEndpoint = new IPEndPoint(IPAddress.Any, 0);

				var asyncResponse = client.BeginReceive(null, null);

				asyncResponse.AsyncWaitHandle.WaitOne(400);

				if (asyncResponse.IsCompleted)
				{
					var response = client.EndReceive(asyncResponse, ref serverReceiveEndpoint);
					if (response.Length == 0)
					{
						throw new InvalidOperationException("Device sent an empty response.");
					}

					return;
				}
				else
				{
					if (tries == 10)
					{
						throw new InvalidOperationException("Timed out.");
					}

					SendColorChangeBytes(requestDataString, tries + 1);
				}
			}
		}

		private static byte[] ToByteArray(string hex) => Enumerable.Range(0, hex.Length / 2).Select(x => Convert.ToByte(hex.Substring(x * 2, 2), 16)).ToArray();
	}
}