MARKUS

using System;

using System.IO;

using System.Net;

using System.Net.NetworkInformation;

using System.Net.Sockets;

using System.Linq;

//using log4net;

namespace Rhino.Licensing.Discovery

{

	///<summary>

	/// Listen to precense notifications

	///</summary>

	public class DiscoveryHost : IDisposable

	{

		private Socket socket;

		private readonly byte[] buffer = new byte[1024*4];

		private const string AllHostsMulticastIP = "224.0.0.1";

		private const int DiscoveryPort = 12391;

        //private static readonly ILog Log = LogManager.GetLogger(typeof(DiscoveryHost));

		///<summary>

		/// Starts listening to network notifications

		///</summary>

		public void Start()

		{

			socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

			socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, 1);

			BindUpAdaptersToMulticast();

			socket.Bind(new IPEndPoint(IPAddress.Any, DiscoveryPort));

			StartListening();

		}

		private void BindUpAdaptersToMulticast()

		{

			NetworkInterface.GetAllNetworkInterfaces()

				.Where(card => card.OperationalStatus == OperationalStatus.Up)

				.ToList()

				.ForEach(SetSocketOptionsForNic);

		}

		private void SetSocketOptionsForNic(NetworkInterface nic)

		{

		    nic.GetIPProperties()

		        .UnicastAddresses

		        .Where(unicast => unicast.Address.AddressFamily == AddressFamily.InterNetwork)

		        .ToList()

		        .ForEach(SafelySetSocketOptionsForAddress);

		}

	    private void SafelySetSocketOptionsForAddress(UnicastIPAddressInformation address)

	    {

	        try

	        {

	            socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership,

	                new MulticastOption(IPAddress.Parse(AllHostsMulticastIP), address.Address));

	        }

	        catch (SocketException ex)

	        {

                throw new Exception($"Setting socket options failed for address: {address?.Address}", ex);

                //Log.Warn($"Setting socket options failed for address: {address?.Address}", ex);

	        }

	    }

		private void StartListening()

		{

			var socketAsyncEventArgs = new SocketAsyncEventArgs

			{

				RemoteEndPoint = new IPEndPoint(IPAddress.Any, 0),

			};

			socketAsyncEventArgs.Completed += Completed;

			socketAsyncEventArgs.SetBuffer(buffer, 0, buffer.Length);

			bool startedAsync;

			try

			{

				startedAsync = socket.ReceiveFromAsync(socketAsyncEventArgs);

			}

			catch (Exception)

			{

				return;

			}

			if (startedAsync == false)

				Completed(this, socketAsyncEventArgs);

		}

		private void Completed(object sender, SocketAsyncEventArgs socketAsyncEventArgs)

		{

			using (socketAsyncEventArgs)

			{

				try

				{

					using (var stream = new MemoryStream(socketAsyncEventArgs.Buffer, 0, socketAsyncEventArgs.BytesTransferred))

					using (var streamReader = new StreamReader(stream))

					{

						var senderId = streamReader.ReadLine();

						var userId = streamReader.ReadLine();

						var clientDiscovered = new ClientDiscoveredEventArgs

						{

							MachineName = streamReader.ReadLine(),

							UserName = streamReader.ReadLine()

						};

						Guid result;

						if (Guid.TryParse(userId, out result))

						{

							clientDiscovered.UserId = result;

						}

						if (Guid.TryParse(senderId, out result))

						{

							clientDiscovered.SenderId = result;

							InvokeClientDiscovered(clientDiscovered);

						}

					}

				}

				catch

				{

				}

				StartListening();

			}

		}

		///<summary>

		/// Notify when a client is discovered

		///</summary>

		public event EventHandler<ClientDiscoveredEventArgs> ClientDiscovered;

		private void InvokeClientDiscovered(ClientDiscoveredEventArgs e)

		{

			EventHandler<ClientDiscoveredEventArgs> handler = ClientDiscovered;

			if (handler != null) handler(this, e);

		}

		/// <summary>

		/// Notification raised when a client is discovered

		/// </summary>

		public class ClientDiscoveredEventArgs : EventArgs

		{

			/// <summary>

			/// The client's license id

			/// </summary>

			public Guid UserId { get; set; }

			/// <summary>

			/// The client machine name

			/// </summary>

			public string MachineName { get; set; }

			/// <summary>

			/// The client user name

			/// </summary>

			public string UserName { get; set; }

			/// <summary>

			/// The id of the sender

			/// </summary>

			public Guid SenderId { get; set; }

		}

        /// <summary>

        /// Disposes of the object

        /// </summary>

		public void Dispose()

		{

			if (socket != null)

				socket.Dispose();

		}

	}

}