Add new mono-compatible websocket provider.

Discord.Net.sln

@@ -1,4 +1,4 @@
-Microsoft Visual Studio Solution File, Format Version 12.00
+Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 15
 VisualStudioVersion = 15.0.26730.12
 MinimumVisualStudioVersion = 10.0.40219.1
@@ -24,6 +24,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Discord.Net.Tests", "test\D
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Discord.Net.Webhook", "src\Discord.Net.Webhook\Discord.Net.Webhook.csproj", "{9AFAB80E-D2D3-4EDB-B58C-BACA78D1EA30}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Discord.Net.Providers.WebSocketSharp", "src\Discord.Net.Providers.WebSocketSharp\Discord.Net.Providers.WebSocketSharp.csproj", "{0748E83F-87A1-4C07-B458-6E438841925B}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -130,6 +132,18 @@ Global
 		{9AFAB80E-D2D3-4EDB-B58C-BACA78D1EA30}.Release|x64.Build.0 = Release|Any CPU
 		{9AFAB80E-D2D3-4EDB-B58C-BACA78D1EA30}.Release|x86.ActiveCfg = Release|Any CPU
 		{9AFAB80E-D2D3-4EDB-B58C-BACA78D1EA30}.Release|x86.Build.0 = Release|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Debug|x64.Build.0 = Debug|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Debug|x86.Build.0 = Debug|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Release|x64.ActiveCfg = Release|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Release|x64.Build.0 = Release|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Release|x86.ActiveCfg = Release|Any CPU
+		{0748E83F-87A1-4C07-B458-6E438841925B}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -141,6 +155,7 @@ Global
 		{688FD1D8-7F01-4539-B2E9-F473C5D699C7} = {288C363D-A636-4EAE-9AC1-4698B641B26E}
 		{6BDEEC08-417B-459F-9CA3-FF8BAB18CAC7} = {B0657AAE-DCC5-4FBF-8E5D-1FB578CF3012}
 		{9AFAB80E-D2D3-4EDB-B58C-BACA78D1EA30} = {CC3D4B1C-9DE0-448B-8AE7-F3F1F3EC5C3A}
+		{0748E83F-87A1-4C07-B458-6E438841925B} = {B0657AAE-DCC5-4FBF-8E5D-1FB578CF3012}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {D2404771-EEC8-45F2-9D71-F3373F6C1495}

src/Discord.Net.Providers.WebSocketSharp/Discord.Net.Providers.WebSocketSharp.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <Import Project="../../Discord.Net.targets" />
+  <PropertyGroup>
+    <AssemblyName>Discord.Net.Providers.WebSocketSharp</AssemblyName>
+    <RootNamespace>Discord.Providers.WebSocketSharp</RootNamespace>
+    <Description>An optional WebSocket client provider for Discord.Net using websocket-sharp</Description>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Discord.Net.Core\Discord.Net.Core.csproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="websocket-sharp-customheaders" Version="1.0.2.31869" />
+  </ItemGroup>
+</Project>

src/Discord.Net.Providers.WebSocketSharp/WebSocketSharpClient.cs

@@ -0,0 +1,223 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Authentication;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Discord.Net;
+using Discord.Net.WebSockets;
+using WebSocketSharp;
+
+namespace Discord.Providers.WebSocketSharp
+{
+    /// <summary>
+	/// WebSocket provider using websocket-sharp.
+	/// </summary>
+	internal class WebSocketSharpClient : IWebSocketClient, IDisposable
+	{
+		/// <inheritdoc />
+		public event Func<byte[], int, int, Task> BinaryMessage;
+
+		/// <inheritdoc />
+		public event Func<string, Task> TextMessage;
+
+		/// <inheritdoc />
+		public event Func<Exception, Task> Closed;
+
+		private readonly SemaphoreSlim _lock;
+		private readonly Dictionary<string, string> _headers;
+		private readonly ManualResetEventSlim _waitUntilConnect;
+
+		private WebSocket _client;
+		private CancellationTokenSource _cancelTokenSource;
+		private CancellationToken _cancelToken;
+		private CancellationToken _parentToken;
+
+		private bool _isDisposed;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="WebSocketSharpProvider"/> class.
+		/// </summary>
+		public WebSocketSharpClient()
+		{
+			_headers = new Dictionary<string, string>();
+			_lock = new SemaphoreSlim(1, 1);
+			_cancelTokenSource = new CancellationTokenSource();
+			_cancelToken = CancellationToken.None;
+			_parentToken = CancellationToken.None;
+			_waitUntilConnect = new ManualResetEventSlim();
+		}
+
+		/// <inheritdoc />
+		public void SetHeader(string key, string value)
+		{
+			_headers[key] = value;
+		}
+
+		/// <inheritdoc />
+		public void SetCancelToken(CancellationToken cancelToken)
+		{
+			_parentToken = cancelToken;
+			_cancelToken = CancellationTokenSource.CreateLinkedTokenSource
+			(
+				_parentToken,
+				_cancelTokenSource.Token
+			)
+			.Token;
+		}
+
+		/// <inheritdoc />
+		public async Task ConnectAsync(string host)
+		{
+			await _lock.WaitAsync().ConfigureAwait(false);
+			try
+			{
+				await ConnectInternalAsync(host).ConfigureAwait(false);
+			}
+			finally
+			{
+				_lock.Release();
+			}
+		}
+
+		private async Task ConnectInternalAsync(string host)
+		{
+			await DisconnectInternalAsync().ConfigureAwait(false);
+
+			_cancelTokenSource = new CancellationTokenSource();
+			_cancelToken = CancellationTokenSource.CreateLinkedTokenSource
+				(
+					_parentToken,
+					_cancelTokenSource.Token
+				)
+				.Token;
+
+			_client = new WebSocket(host)
+			{
+				CustomHeaders = _headers.ToList()
+			};
+			_client.SslConfiguration.EnabledSslProtocols = SslProtocols.Tls12;
+
+			_client.OnMessage += OnMessage;
+			_client.OnOpen += OnConnected;
+			_client.OnClose += OnClosed;
+
+			_client.Connect();
+			_waitUntilConnect.Wait(_cancelToken);
+		}
+
+		/// <inheritdoc />
+		public async Task DisconnectAsync()
+		{
+			await _lock.WaitAsync().ConfigureAwait(false);
+			try
+			{
+				await DisconnectInternalAsync().ConfigureAwait(false);
+			}
+			finally
+			{
+				_lock.Release();
+			}
+		}
+
+		private Task DisconnectInternalAsync()
+		{
+			_cancelTokenSource.Cancel();
+			if (_client is null)
+			{
+				return Task.CompletedTask;
+			}
+
+			if (_client.ReadyState == WebSocketState.Open)
+			{
+				_client.Close();
+			}
+
+			_client.OnMessage -= OnMessage;
+			_client.OnOpen -= OnConnected;
+			_client.OnClose -= OnClosed;
+
+			_client = null;
+			_waitUntilConnect.Reset();
+
+			return Task.CompletedTask;
+		}
+
+		private void OnMessage(object sender, MessageEventArgs messageEventArgs)
+		{
+			if (messageEventArgs.IsBinary)
+			{
+				OnBinaryMessage(messageEventArgs);
+			}
+			else if (messageEventArgs.IsText)
+			{
+				OnTextMessage(messageEventArgs);
+			}
+		}
+
+		/// <inheritdoc />
+		public async Task SendAsync(byte[] data, int index, int count, bool isText)
+		{
+			await _lock.WaitAsync(_cancelToken).ConfigureAwait(false);
+			try
+			{
+				if (isText)
+				{
+					_client.Send(Encoding.UTF8.GetString(data, index, count));
+				}
+				else
+				{
+					_client.Send(data.Skip(index).Take(count).ToArray());
+				}
+			}
+			finally
+			{
+				_lock.Release();
+			}
+		}
+
+		private void OnTextMessage(MessageEventArgs e)
+		{
+			TextMessage?.Invoke(e.Data).GetAwaiter().GetResult();
+		}
+
+		private void OnBinaryMessage(MessageEventArgs e)
+		{
+			BinaryMessage?.Invoke(e.RawData, 0, e.RawData.Length).GetAwaiter().GetResult();
+		}
+
+		private void OnConnected(object sender, EventArgs e)
+		{
+			_waitUntilConnect.Set();
+		}
+
+		private void OnClosed(object sender, CloseEventArgs e)
+		{
+			if (e.WasClean)
+			{
+				Closed?.Invoke(null).GetAwaiter().GetResult();
+				return;
+			}
+
+			var ex = new WebSocketClosedException(e.Code, e.Reason);
+			Closed?.Invoke(ex).GetAwaiter().GetResult();
+		}
+
+		/// <inheritdoc />
+		public void Dispose()
+		{
+			if (_isDisposed)
+			{
+				return;
+			}
+
+			DisconnectInternalAsync().GetAwaiter().GetResult();
+
+			((IDisposable)_client)?.Dispose();
+			_client = null;
+
+			_isDisposed = true;
+		}
+	}
+}

src/Discord.Net.Providers.WebSocketSharp/WebSocketSharpProvider.cs

@@ -0,0 +1,9 @@
+using Discord.Net.WebSockets;
+
+namespace Discord.Providers.WebSocketSharp
+{
+    public static class WebSocketSharpProvider
+    {
+        public static readonly WebSocketProvider Instance = () => new WebSocketSharpClient();
+    }
+}