Merge from develop.

Source/MQTTnet.AspnetCore/AspNetMqttServerOptionsBuilder.cs

@@ -0,0 +1,15 @@
+using MQTTnet.Server;
+using System;
+
+namespace MQTTnet.AspNetCore
+{
+    public class AspNetMqttServerOptionsBuilder : MqttServerOptionsBuilder
+    {
+        public AspNetMqttServerOptionsBuilder(IServiceProvider serviceProvider)
+        {
+            ServiceProvider = serviceProvider;
+        }
+
+        public IServiceProvider ServiceProvider { get; }
+    }
+}

Source/MQTTnet.AspnetCore/MQTTnet.AspNetCore.csproj

@@ -14,9 +14,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="2.1.0" />
-    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.0.1" />
-    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.0.1" />
+    <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="2.1.3" />
+    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.1.1" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.1.1" />
   </ItemGroup>
 
   <ItemGroup>

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Connections;
 using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
+using MQTTnet.Exceptions;
 using MQTTnet.Packets;
 using MQTTnet.Serializer;
 using System;
@@ -24,6 +25,8 @@ namespace MQTTnet.AspNetCore
         public event EventHandler ReadingPacketStarted;
         public event EventHandler ReadingPacketCompleted;
 
+        private readonly SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
+
         public Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             if (Connection is TcpConnection tcp && !tcp.IsConnected)
@@ -57,7 +60,7 @@ namespace MQTTnet.AspNetCore
                     }
                     else
                     {
-                        readResult = await readTask;
+                        readResult = await readTask.ConfigureAwait(false);
                     }
 
                     var buffer = readResult.Buffer;
@@ -81,7 +84,7 @@ namespace MQTTnet.AspNetCore
                         }
                         else if (readResult.IsCompleted)
                         {
-                            break;
+                            throw new MqttCommunicationException("Connection Aborted");
                         }
                     }
                     finally
@@ -102,10 +105,20 @@ namespace MQTTnet.AspNetCore
             return null;
         }
 
-        public Task SendPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
+        public async Task SendPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
         {
-            var buffer = PacketSerializerAdapter.Serialize(packet);
-            return Connection.Transport.Output.WriteAsync(buffer.AsMemory(), cancellationToken).AsTask();
+            var buffer = PacketSerializer.Serialize(packet).AsMemory();
+            var output = Connection.Transport.Output;
+
+            await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
+            try
+            {
+                await output.WriteAsync(buffer, cancellationToken).ConfigureAwait(false);
+            }
+            finally
+            {
+                _writerSemaphore.Release();
+            }
         }
 
         public void Dispose()

Source/MQTTnet.AspnetCore/ServiceCollectionExtensions.cs

@@ -20,14 +20,27 @@ namespace MQTTnet.AspNetCore
 
             return services;
         }
-        
+
         public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, Action<MqttServerOptionsBuilder> configure)
         {
-            var builder = new MqttServerOptionsBuilder();
+            services.AddSingleton<IMqttServerOptions>(s => {
+                var builder = new MqttServerOptionsBuilder();
+                configure(builder);
+                return builder.Build();
+            });
 
-            configure(builder);
-            
-            services.AddSingleton<IMqttServerOptions>(builder.Build());
+            services.AddHostedMqttServer();
+
+            return services;
+        }
+
+        public static IServiceCollection AddHostedMqttServerWithServices(this IServiceCollection services, Action<AspNetMqttServerOptionsBuilder> configure)
+        {
+            services.AddSingleton<IMqttServerOptions>(s => {
+                var builder = new AspNetMqttServerOptionsBuilder(s);
+                configure(builder);
+                return builder.Build();
+            });
 
             services.AddHostedMqttServer();