jellyfin/Emby.Server.Implementations/Udp/UdpServer.cs
2021-10-03 21:41:22 -04:00

146 lines
4.9 KiB
C#

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using MediaBrowser.Controller;
using MediaBrowser.Model.ApiClient;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
namespace Emby.Server.Implementations.Udp
{
/// <summary>
/// Provides a Udp Server.
/// </summary>
public sealed class UdpServer : IDisposable
{
/// <summary>
/// Address Override Configuration Key.
/// </summary>
public const string AddressOverrideConfigKey = "PublishedServerUrl";
/// <summary>
/// The _logger.
/// </summary>
private readonly ILogger _logger;
private readonly IServerApplicationHost _appHost;
private readonly IConfiguration _config;
private readonly byte[] _receiveBuffer = new byte[8192];
private Socket _udpSocket;
private IPEndPoint _endpoint;
private bool _disposed = false;
/// <summary>
/// Initializes a new instance of the <see cref="UdpServer" /> class.
/// </summary>
/// <param name="logger">The logger.</param>
/// <param name="appHost">The application host.</param>
/// <param name="configuration">The configuration manager.</param>
/// <param name="port">The port.</param>
public UdpServer(
ILogger logger,
IServerApplicationHost appHost,
IConfiguration configuration,
int port)
{
_logger = logger;
_appHost = appHost;
_config = configuration;
_endpoint = new IPEndPoint(IPAddress.Any, port);
_udpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
_udpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
}
private async Task RespondToV2Message(string messageText, EndPoint endpoint, CancellationToken cancellationToken)
{
string? localUrl = _config[AddressOverrideConfigKey];
if (string.IsNullOrEmpty(localUrl))
{
localUrl = _appHost.GetSmartApiUrl(((IPEndPoint)endpoint).Address);
}
if (string.IsNullOrEmpty(localUrl))
{
_logger.LogWarning("Unable to respond to udp request because the local ip address could not be determined.");
return;
}
var response = new ServerDiscoveryInfo(localUrl, _appHost.SystemId, _appHost.FriendlyName);
try
{
await _udpSocket.SendToAsync(JsonSerializer.SerializeToUtf8Bytes(response), SocketFlags.None, endpoint).ConfigureAwait(false);
}
catch (SocketException ex)
{
_logger.LogError(ex, "Error sending response message");
}
}
/// <summary>
/// Starts the specified port.
/// </summary>
/// <param name="cancellationToken">The cancellation token to cancel operation.</param>
public void Start(CancellationToken cancellationToken)
{
_udpSocket.Bind(_endpoint);
_ = Task.Run(async () => await BeginReceiveAsync(cancellationToken).ConfigureAwait(false), cancellationToken).ConfigureAwait(false);
}
private async Task BeginReceiveAsync(CancellationToken cancellationToken)
{
var infiniteTask = Task.Delay(-1, cancellationToken);
while (!cancellationToken.IsCancellationRequested)
{
try
{
var task = _udpSocket.ReceiveFromAsync(_receiveBuffer, SocketFlags.None, _endpoint);
await Task.WhenAny(task, infiniteTask).ConfigureAwait(false);
if (!task.IsCompleted)
{
return;
}
var result = task.Result;
var text = Encoding.UTF8.GetString(_receiveBuffer, 0, result.ReceivedBytes);
if (text.Contains("who is JellyfinServer?", StringComparison.OrdinalIgnoreCase))
{
await RespondToV2Message(text, result.RemoteEndPoint, cancellationToken).ConfigureAwait(false);
}
}
catch (SocketException ex)
{
_logger.LogError(ex, "Failed to receive data from socket");
}
catch (OperationCanceledException)
{
// Don't throw
}
}
}
/// <inheritdoc />
public void Dispose()
{
if (_disposed)
{
return;
}
_udpSocket?.Dispose();
GC.SuppressFinalize(this);
}
}
}