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using Google.Protobuf;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;
using System.Timers;
using Tango.Core;
using Tango.PMR.Discovery;
using Tango.Transport.Servers;
namespace Tango.Transport.Discovery
{
/// <summary>
/// Represents UDP discovery service broadcasting a discovery message of type <see cref="BasicDiscoveryMessage"/>.
/// </summary>
/// <seealso cref="Tango.Transport.Discovery.IDiscoveryService{Tango.PMR.Discovery.BasicDiscoveryMessage}" />
public class UdpDiscoveryService<DiscoveryMessage> : ExtendedObject, IDiscoveryService<DiscoveryMessage> where DiscoveryMessage : IMessage
{
private Timer _timer;
private TcpServer _tcpValidationServer;
/// <summary>
/// Occurs before broadcasting the discovery message and gives a chance to modify the packet message.
/// </summary>
public event EventHandler<DiscoveryMessage> BeforeBroadcasting;
/// <summary>
/// Gets or sets the current discovery message.
/// </summary>
public DiscoveryMessage CurrentDiscoveryMessage { get; set; }
/// <summary>
/// Gets or sets the interval in which the discovery message will be sent.
/// </summary>
public TimeSpan Interval { get; set; }
/// <summary>
/// Gets a value indicating whether this service has been started.
/// </summary>
public bool IsStarted { get; private set; }
/// <summary>
/// Gets the UDP port number.
/// </summary>
public int Port { get; private set; }
/// <summary>
/// Prevents a default instance of the <see cref="UdpDiscoveryService{DiscoveryMessage}"/> class from being created.
/// </summary>
private UdpDiscoveryService()
{
Interval = TimeSpan.FromSeconds(5);
CurrentDiscoveryMessage = Activator.CreateInstance<DiscoveryMessage>();
}
/// <summary>
/// Initializes a new instance of the <see cref="UdpDiscoveryService{DiscoveryMessage}"/> class.
/// </summary>
/// <param name="port">The port.</param>
public UdpDiscoveryService(int port) : this()
{
Port = port;
_tcpValidationServer = new TcpServer(Port);
_tcpValidationServer.ClientConnected += (x, e) =>
{
e.Socket.Dispose();
};
}
/// <summary>
/// Initializes a new instance of the <see cref="UdpDiscoveryService{DiscoveryMessage}"/> class.
/// </summary>
/// <param name="port">The port.</param>
/// <param name="discoveryMessage">The discovery message.</param>
public UdpDiscoveryService(int port, DiscoveryMessage discoveryMessage) : this(port)
{
CurrentDiscoveryMessage = discoveryMessage;
}
/// <summary>
/// Starts the discovery service.
/// </summary>
public void Start()
{
if (!IsStarted)
{
_tcpValidationServer.Start();
_timer = new Timer();
_timer.Interval = Interval.TotalMilliseconds;
_timer.Elapsed += _timer_Elapsed;
_timer.Enabled = true;
_timer.Start();
IsStarted = true;
}
}
/// <summary>
/// Stops the discovery service.
/// </summary>
public void Stop()
{
if (IsStarted)
{
_tcpValidationServer.Stop();
//Transmit the discovery packet one more time so clients can tell that we have disconnected.
BroadcastDiscoveryPacket();
_timer.Stop();
IsStarted = false;
}
}
/// <summary>
/// Handles the Elapsed event of the _timer control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="ElapsedEventArgs"/> instance containing the event data.</param>
private void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
BroadcastDiscoveryPacket();
}
private void BroadcastDiscoveryPacket()
{
try
{
UdpClient client = new UdpClient();
IPEndPoint endPoint = new IPEndPoint(IPAddress.Broadcast, Port);
BeforeBroadcasting?.Invoke(this, CurrentDiscoveryMessage);
byte[] bytes = CurrentDiscoveryMessage.ToByteArray();
client.EnableBroadcast = true;
client.Send(bytes, bytes.Length, endPoint);
client.Close();
}
catch (Exception ex)
{
LogManager.Log(ex, "Error broadcasting discovery packet.");
}
}
}
}
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