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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;
using System.Threading.Tasks;
using System.Timers;
using Tango.PMR.Discovery;
namespace Tango.Transport.Discovery
{
public class UdpDiscoveryClient<DiscoveryMessage> : IDiscoveryClient<DiscoveryMessage> where DiscoveryMessage : IMessage
{
private Thread _receiveThread;
/// <summary>
/// Occurs when a matching service has been discovered.
/// </summary>
public event EventHandler<DiscoveredService<DiscoveryMessage>> ServiceDiscovered;
/// <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="UdpDiscoveryClient"/> class from being created.
/// </summary>
private UdpDiscoveryClient()
{
Interval = TimeSpan.FromSeconds(5);
}
/// <summary>
/// Initializes a new instance of the <see cref="UdpDiscoveryClient"/> class.
/// </summary>
/// <param name="port">The UDP port number.</param>
public UdpDiscoveryClient(int port) : this()
{
Port = port;
}
/// <summary>
/// Starts the discovery client.
/// </summary>
public void Start()
{
if (!IsStarted)
{
IsStarted = true;
_receiveThread = new Thread(ReceiveThreadLoop);
_receiveThread.IsBackground = true;
_receiveThread.Start();
}
}
/// <summary>
/// Stops the discovery client.
/// </summary>
public void Stop()
{
if (IsStarted)
{
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 ReceiveThreadLoop()
{
UdpClient udpClient = new UdpClient(Port);
udpClient.Client.ReceiveTimeout = (int)Interval.TotalMilliseconds;
var endPoint = new IPEndPoint(IPAddress.Any, Port);
while (IsStarted)
{
try
{
byte[] data = null;
do
{
data = udpClient.Receive(ref endPoint);
if (IsStarted)
{
if (data != null && data.Length > 0)
{
DiscoveryMessage message = Activator.CreateInstance<DiscoveryMessage>();
var parser = message.GetParser();
message = (DiscoveryMessage)parser.ParseFrom(data);
var host = Dns.GetHostEntry(endPoint.Address);
string address = endPoint.Address.ToString();
ServiceDiscovered?.Invoke(this,
new DiscoveredService<DiscoveryMessage>(
address,
host != null ? host.HostName : "Unresolved",
message
, () =>
{
try
{
TcpClient client = new TcpClient();
client.Connect(address, Port);
client.Dispose();
return true;
}
catch
{
return false;
}
}));
}
}
} while (IsStarted && data != null && data.Length > 0);
}
catch { }
if (!IsStarted) break;
Thread.Sleep(Interval);
}
udpClient.Close();
}
/// <summary>
/// Asynchronous method for awaiting until the service will be discovered.
/// </summary>
/// <param name="timeout"></param>
/// <returns></returns>
public Task<DiscoveredService<DiscoveryMessage>> Discover(TimeSpan? timeout = null)
{
Start();
TaskCompletionSource<DiscoveredService<DiscoveryMessage>> source = new TaskCompletionSource<DiscoveredService<DiscoveryMessage>>();
EventHandler<DiscoveredService<DiscoveryMessage>> handler = null;
handler = (sender, e) =>
{
ServiceDiscovered -= handler;
source.SetResult(e);
};
ServiceDiscovered += handler;
Task.Delay(timeout != null ? timeout.Value : TimeSpan.FromSeconds(10)).ContinueWith((x) =>
{
if (!source.Task.IsCompleted)
{
source.SetException(new TimeoutException());
}
});
return source.Task;
}
}
}
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