BITKit/Src/Core/Net/LAN/UdpBasedLanBroadcaster.cs

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

namespace BITKit.Net.LAN
{
	/// <summary>
	/// 基于UDP的LAN广播
	/// </summary>
	public class UdpBasedLanBroadcaster : ILANBroadcaster
	{
		public int Port { get; set; }
		public byte[] Buffer { get; set; } = StringHelper.GetBytes("Hello World");
		private bool _isBroadcasting;
		private bool _isListening;
		private int head;
		private int revHead;

		private Thread _thread;

		public UdpBasedLanBroadcaster()
		{

		}

		public event Action<EndPoint, byte[]> OnReceive;

		public void StartBroadcast()
		{
			_isBroadcasting = true;
			_thread = new(Process)
			{
				IsBackground = true
			};
			_thread.Start();
			BIT4Log.Log<ILANBroadcaster>($"开始广播端口{Port}");
		}

		public void StopBroadcast()
		{
			_isBroadcasting = false;
			BIT4Log.Log<ILANBroadcaster>($"停止广播端口 {Port}");
		}

		public void StartListen()
		{
			if (_isListening) return;
			_isListening = true;
			_thread = new Thread(ReceiveThread)
			{
				IsBackground = true
			};
			_thread.Start();
			BIT4Log.Log<ILANBroadcaster>($"开始监听端口:{Port}");
		}
		public void StopListen()
		{
			if (_isListening is false) return;
			_isListening = false;
			_thread?.Abort();
			BIT4Log.Log<ILANBroadcaster>($"停止监听端口{Port}");
		}

		public void Process()
		{
			var udpClient = new UdpClient(new IPEndPoint(IPAddress.Any, 0));
			
			var endpoint = new IPEndPoint(IPAddress.Broadcast, Port);
			//其实 IPAddress.Broadcast 就是 255.255.255.255
			//下面代码与上面有相同的作用
			//IPEndPoint endpoint = new IPEndPoint(IPAddress.Parse("255.255.255.255"), 8080);
			try
			{
				var tempBuffer = new byte[Buffer.Length + 1];
				tempBuffer[0] = (byte)head++;
				Buffer.CopyTo(tempBuffer, 1);
					udpClient.Send(tempBuffer, tempBuffer.Length, endpoint);
					Thread.Sleep(1000);
				while (_isBroadcasting)
				{
					udpClient.Send(tempBuffer, tempBuffer.Length, endpoint);
					Thread.Sleep(1000);
				}
			}
			catch (Exception e)
			{
				BIT4Log.LogException(e);
			}
			udpClient.Dispose();
		}

		private void ReceiveThread()
		{
			try
			{
				var udpClient = new UdpClient(new IPEndPoint(IPAddress.Any, Port));
				var endpoint = new IPEndPoint(IPAddress.Any, 0);
				while (_isListening &&  BITApp.CancellationToken.IsCancellationRequested is false)
				{
					byte[] buf;
					try
					{
						buf = udpClient.Receive(ref endpoint);
					}
					catch (ThreadAbortException)
					{
						udpClient.Dispose();
						return;
					}
					var packageHead = buf[0];
					if(packageHead<revHead)
						continue;
					revHead = packageHead;
					buf = buf[1..];
					if (OnReceive is not null)
						OnReceive(endpoint, buf);
					else
						BIT4Log.Log<ILANBroadcaster>($"Receive From {endpoint}:\t{buf}");
					Thread.Sleep(500);
				}
				udpClient.Dispose();
			}
			catch(ThreadAbortException){}
			catch (Exception e)
			{
				BIT4Log.LogException(e);
			}
		
		}

		public void Dispose()
		{
			StopBroadcast();
			StopListen();
			OnReceive = null;
		}
	}
}